3840 lines
109 KiB
C
3840 lines
109 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/bpf.h>
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#include <linux/bpf_verifier.h>
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#include <linux/filter.h>
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#include <net/netlink.h>
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#include <linux/file.h>
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#include <linux/vmalloc.h>
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#include <linux/stringify.h>
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/* bpf_check() is a static code analyzer that walks eBPF program
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* instruction by instruction and updates register/stack state.
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* All paths of conditional branches are analyzed until 'bpf_exit' insn.
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*
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* The first pass is depth-first-search to check that the program is a DAG.
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* It rejects the following programs:
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* - larger than BPF_MAXINSNS insns
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* - if loop is present (detected via back-edge)
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* - unreachable insns exist (shouldn't be a forest. program = one function)
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* - out of bounds or malformed jumps
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* The second pass is all possible path descent from the 1st insn.
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* Since it's analyzing all pathes through the program, the length of the
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* analysis is limited to 64k insn, which may be hit even if total number of
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* insn is less then 4K, but there are too many branches that change stack/regs.
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* Number of 'branches to be analyzed' is limited to 1k
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*
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* On entry to each instruction, each register has a type, and the instruction
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* changes the types of the registers depending on instruction semantics.
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* If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
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* copied to R1.
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*
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* All registers are 64-bit.
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* R0 - return register
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* R1-R5 argument passing registers
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* R6-R9 callee saved registers
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* R10 - frame pointer read-only
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*
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* At the start of BPF program the register R1 contains a pointer to bpf_context
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* and has type PTR_TO_CTX.
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*
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* Verifier tracks arithmetic operations on pointers in case:
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* BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
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* BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
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* 1st insn copies R10 (which has FRAME_PTR) type into R1
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* and 2nd arithmetic instruction is pattern matched to recognize
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* that it wants to construct a pointer to some element within stack.
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* So after 2nd insn, the register R1 has type PTR_TO_STACK
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* (and -20 constant is saved for further stack bounds checking).
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* Meaning that this reg is a pointer to stack plus known immediate constant.
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*
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* Most of the time the registers have UNKNOWN_VALUE type, which
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* means the register has some value, but it's not a valid pointer.
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* (like pointer plus pointer becomes UNKNOWN_VALUE type)
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*
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* When verifier sees load or store instructions the type of base register
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* can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer
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* types recognized by check_mem_access() function.
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*
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* PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
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* and the range of [ptr, ptr + map's value_size) is accessible.
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*
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* registers used to pass values to function calls are checked against
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* function argument constraints.
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*
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* ARG_PTR_TO_MAP_KEY is one of such argument constraints.
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* It means that the register type passed to this function must be
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* PTR_TO_STACK and it will be used inside the function as
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* 'pointer to map element key'
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*
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* For example the argument constraints for bpf_map_lookup_elem():
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* .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
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* .arg1_type = ARG_CONST_MAP_PTR,
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* .arg2_type = ARG_PTR_TO_MAP_KEY,
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*
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* ret_type says that this function returns 'pointer to map elem value or null'
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* function expects 1st argument to be a const pointer to 'struct bpf_map' and
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* 2nd argument should be a pointer to stack, which will be used inside
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* the helper function as a pointer to map element key.
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*
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* On the kernel side the helper function looks like:
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* u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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* {
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* struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
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* void *key = (void *) (unsigned long) r2;
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* void *value;
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*
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* here kernel can access 'key' and 'map' pointers safely, knowing that
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* [key, key + map->key_size) bytes are valid and were initialized on
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* the stack of eBPF program.
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* }
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*
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* Corresponding eBPF program may look like:
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* BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
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* BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
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* BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
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* BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
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* here verifier looks at prototype of map_lookup_elem() and sees:
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* .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
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* Now verifier knows that this map has key of R1->map_ptr->key_size bytes
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*
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* Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
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* Now verifier checks that [R2, R2 + map's key_size) are within stack limits
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* and were initialized prior to this call.
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* If it's ok, then verifier allows this BPF_CALL insn and looks at
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* .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
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* R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
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* returns ether pointer to map value or NULL.
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*
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* When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
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* insn, the register holding that pointer in the true branch changes state to
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* PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
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* branch. See check_cond_jmp_op().
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*
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* After the call R0 is set to return type of the function and registers R1-R5
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* are set to NOT_INIT to indicate that they are no longer readable.
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*/
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/* verifier_state + insn_idx are pushed to stack when branch is encountered */
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struct bpf_verifier_stack_elem {
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/* verifer state is 'st'
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* before processing instruction 'insn_idx'
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* and after processing instruction 'prev_insn_idx'
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*/
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struct bpf_verifier_state st;
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int insn_idx;
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int prev_insn_idx;
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struct bpf_verifier_stack_elem *next;
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};
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#define BPF_COMPLEXITY_LIMIT_INSNS 98304
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#define BPF_COMPLEXITY_LIMIT_STACK 1024
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#define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA)
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struct bpf_call_arg_meta {
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struct bpf_map *map_ptr;
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bool raw_mode;
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bool pkt_access;
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int regno;
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int access_size;
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};
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/* verbose verifier prints what it's seeing
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* bpf_check() is called under lock, so no race to access these global vars
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*/
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static u32 log_level, log_size, log_len;
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static char *log_buf;
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static DEFINE_MUTEX(bpf_verifier_lock);
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/* log_level controls verbosity level of eBPF verifier.
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* verbose() is used to dump the verification trace to the log, so the user
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* can figure out what's wrong with the program
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*/
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static __printf(1, 2) void verbose(const char *fmt, ...)
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{
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va_list args;
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if (log_level == 0 || log_len >= log_size - 1)
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return;
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va_start(args, fmt);
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log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args);
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va_end(args);
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}
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/* string representation of 'enum bpf_reg_type' */
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static const char * const reg_type_str[] = {
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[NOT_INIT] = "?",
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[UNKNOWN_VALUE] = "inv",
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[PTR_TO_CTX] = "ctx",
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[CONST_PTR_TO_MAP] = "map_ptr",
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[PTR_TO_MAP_VALUE] = "map_value",
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[PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
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[PTR_TO_MAP_VALUE_ADJ] = "map_value_adj",
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[FRAME_PTR] = "fp",
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[PTR_TO_STACK] = "fp",
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[CONST_IMM] = "imm",
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[PTR_TO_PACKET] = "pkt",
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[PTR_TO_PACKET_END] = "pkt_end",
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};
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#define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
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static const char * const func_id_str[] = {
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__BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN)
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};
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#undef __BPF_FUNC_STR_FN
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static const char *func_id_name(int id)
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{
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BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID);
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if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id])
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return func_id_str[id];
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else
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return "unknown";
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}
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static void print_verifier_state(struct bpf_verifier_state *state)
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{
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struct bpf_reg_state *reg;
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enum bpf_reg_type t;
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int i;
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for (i = 0; i < MAX_BPF_REG; i++) {
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reg = &state->regs[i];
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t = reg->type;
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if (t == NOT_INIT)
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continue;
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verbose(" R%d=%s", i, reg_type_str[t]);
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if (t == CONST_IMM || t == PTR_TO_STACK)
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verbose("%lld", reg->imm);
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else if (t == PTR_TO_PACKET)
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verbose("(id=%d,off=%d,r=%d)",
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reg->id, reg->off, reg->range);
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else if (t == UNKNOWN_VALUE && reg->imm)
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verbose("%lld", reg->imm);
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else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE ||
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t == PTR_TO_MAP_VALUE_OR_NULL ||
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t == PTR_TO_MAP_VALUE_ADJ)
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verbose("(ks=%d,vs=%d,id=%u)",
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reg->map_ptr->key_size,
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reg->map_ptr->value_size,
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reg->id);
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if (reg->min_value != BPF_REGISTER_MIN_RANGE)
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verbose(",min_value=%lld",
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(long long)reg->min_value);
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if (reg->max_value != BPF_REGISTER_MAX_RANGE)
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verbose(",max_value=%llu",
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(unsigned long long)reg->max_value);
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if (reg->min_align)
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verbose(",min_align=%u", reg->min_align);
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if (reg->aux_off)
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verbose(",aux_off=%u", reg->aux_off);
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if (reg->aux_off_align)
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verbose(",aux_off_align=%u", reg->aux_off_align);
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}
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for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
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if (state->stack_slot_type[i] == STACK_SPILL)
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verbose(" fp%d=%s", -MAX_BPF_STACK + i,
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reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]);
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}
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verbose("\n");
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}
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static const char *const bpf_class_string[] = {
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[BPF_LD] = "ld",
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[BPF_LDX] = "ldx",
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[BPF_ST] = "st",
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[BPF_STX] = "stx",
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[BPF_ALU] = "alu",
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[BPF_JMP] = "jmp",
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[BPF_RET] = "BUG",
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[BPF_ALU64] = "alu64",
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};
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static const char *const bpf_alu_string[16] = {
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[BPF_ADD >> 4] = "+=",
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[BPF_SUB >> 4] = "-=",
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[BPF_MUL >> 4] = "*=",
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[BPF_DIV >> 4] = "/=",
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[BPF_OR >> 4] = "|=",
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[BPF_AND >> 4] = "&=",
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[BPF_LSH >> 4] = "<<=",
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[BPF_RSH >> 4] = ">>=",
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[BPF_NEG >> 4] = "neg",
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[BPF_MOD >> 4] = "%=",
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[BPF_XOR >> 4] = "^=",
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[BPF_MOV >> 4] = "=",
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[BPF_ARSH >> 4] = "s>>=",
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[BPF_END >> 4] = "endian",
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};
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static const char *const bpf_ldst_string[] = {
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[BPF_W >> 3] = "u32",
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[BPF_H >> 3] = "u16",
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[BPF_B >> 3] = "u8",
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[BPF_DW >> 3] = "u64",
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};
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static const char *const bpf_jmp_string[16] = {
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[BPF_JA >> 4] = "jmp",
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[BPF_JEQ >> 4] = "==",
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[BPF_JGT >> 4] = ">",
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[BPF_JGE >> 4] = ">=",
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[BPF_JSET >> 4] = "&",
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[BPF_JNE >> 4] = "!=",
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[BPF_JSGT >> 4] = "s>",
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[BPF_JSGE >> 4] = "s>=",
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[BPF_CALL >> 4] = "call",
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[BPF_EXIT >> 4] = "exit",
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};
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static void print_bpf_insn(const struct bpf_verifier_env *env,
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const struct bpf_insn *insn)
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{
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u8 class = BPF_CLASS(insn->code);
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if (class == BPF_ALU || class == BPF_ALU64) {
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if (BPF_SRC(insn->code) == BPF_X)
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verbose("(%02x) %sr%d %s %sr%d\n",
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insn->code, class == BPF_ALU ? "(u32) " : "",
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insn->dst_reg,
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bpf_alu_string[BPF_OP(insn->code) >> 4],
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class == BPF_ALU ? "(u32) " : "",
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insn->src_reg);
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else
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verbose("(%02x) %sr%d %s %s%d\n",
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insn->code, class == BPF_ALU ? "(u32) " : "",
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insn->dst_reg,
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bpf_alu_string[BPF_OP(insn->code) >> 4],
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class == BPF_ALU ? "(u32) " : "",
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insn->imm);
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} else if (class == BPF_STX) {
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if (BPF_MODE(insn->code) == BPF_MEM)
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verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->dst_reg,
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insn->off, insn->src_reg);
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else if (BPF_MODE(insn->code) == BPF_XADD)
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verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->dst_reg, insn->off,
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insn->src_reg);
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else
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verbose("BUG_%02x\n", insn->code);
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} else if (class == BPF_ST) {
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if (BPF_MODE(insn->code) != BPF_MEM) {
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verbose("BUG_st_%02x\n", insn->code);
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return;
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}
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verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->dst_reg,
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insn->off, insn->imm);
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} else if (class == BPF_LDX) {
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if (BPF_MODE(insn->code) != BPF_MEM) {
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verbose("BUG_ldx_%02x\n", insn->code);
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return;
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}
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verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
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insn->code, insn->dst_reg,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->src_reg, insn->off);
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} else if (class == BPF_LD) {
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if (BPF_MODE(insn->code) == BPF_ABS) {
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verbose("(%02x) r0 = *(%s *)skb[%d]\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->imm);
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} else if (BPF_MODE(insn->code) == BPF_IND) {
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verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->src_reg, insn->imm);
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} else if (BPF_MODE(insn->code) == BPF_IMM &&
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BPF_SIZE(insn->code) == BPF_DW) {
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/* At this point, we already made sure that the second
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* part of the ldimm64 insn is accessible.
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*/
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u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
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bool map_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD;
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if (map_ptr && !env->allow_ptr_leaks)
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imm = 0;
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verbose("(%02x) r%d = 0x%llx\n", insn->code,
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insn->dst_reg, (unsigned long long)imm);
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} else {
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verbose("BUG_ld_%02x\n", insn->code);
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return;
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}
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} else if (class == BPF_JMP) {
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u8 opcode = BPF_OP(insn->code);
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if (opcode == BPF_CALL) {
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verbose("(%02x) call %s#%d\n", insn->code,
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func_id_name(insn->imm), insn->imm);
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} else if (insn->code == (BPF_JMP | BPF_JA)) {
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verbose("(%02x) goto pc%+d\n",
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insn->code, insn->off);
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} else if (insn->code == (BPF_JMP | BPF_EXIT)) {
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verbose("(%02x) exit\n", insn->code);
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} else if (BPF_SRC(insn->code) == BPF_X) {
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verbose("(%02x) if r%d %s r%d goto pc%+d\n",
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insn->code, insn->dst_reg,
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bpf_jmp_string[BPF_OP(insn->code) >> 4],
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insn->src_reg, insn->off);
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} else {
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verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
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insn->code, insn->dst_reg,
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bpf_jmp_string[BPF_OP(insn->code) >> 4],
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insn->imm, insn->off);
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}
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} else {
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verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
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}
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}
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|
|
static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx)
|
|
{
|
|
struct bpf_verifier_stack_elem *elem;
|
|
int insn_idx;
|
|
|
|
if (env->head == NULL)
|
|
return -1;
|
|
|
|
memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
|
|
insn_idx = env->head->insn_idx;
|
|
if (prev_insn_idx)
|
|
*prev_insn_idx = env->head->prev_insn_idx;
|
|
elem = env->head->next;
|
|
kfree(env->head);
|
|
env->head = elem;
|
|
env->stack_size--;
|
|
return insn_idx;
|
|
}
|
|
|
|
static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
|
|
int insn_idx, int prev_insn_idx)
|
|
{
|
|
struct bpf_verifier_stack_elem *elem;
|
|
|
|
elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
|
|
if (!elem)
|
|
goto err;
|
|
|
|
memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state));
|
|
elem->insn_idx = insn_idx;
|
|
elem->prev_insn_idx = prev_insn_idx;
|
|
elem->next = env->head;
|
|
env->head = elem;
|
|
env->stack_size++;
|
|
if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
|
|
verbose("BPF program is too complex\n");
|
|
goto err;
|
|
}
|
|
return &elem->st;
|
|
err:
|
|
/* pop all elements and return */
|
|
while (pop_stack(env, NULL) >= 0);
|
|
return NULL;
|
|
}
|
|
|
|
#define CALLER_SAVED_REGS 6
|
|
static const int caller_saved[CALLER_SAVED_REGS] = {
|
|
BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
|
|
};
|
|
|
|
static void mark_reg_not_init(struct bpf_reg_state *regs, u32 regno)
|
|
{
|
|
BUG_ON(regno >= MAX_BPF_REG);
|
|
|
|
memset(®s[regno], 0, sizeof(regs[regno]));
|
|
regs[regno].type = NOT_INIT;
|
|
regs[regno].min_value = BPF_REGISTER_MIN_RANGE;
|
|
regs[regno].max_value = BPF_REGISTER_MAX_RANGE;
|
|
}
|
|
|
|
static void init_reg_state(struct bpf_reg_state *regs)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++)
|
|
mark_reg_not_init(regs, i);
|
|
|
|
/* frame pointer */
|
|
regs[BPF_REG_FP].type = FRAME_PTR;
|
|
|
|
/* 1st arg to a function */
|
|
regs[BPF_REG_1].type = PTR_TO_CTX;
|
|
}
|
|
|
|
static void __mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
|
|
{
|
|
regs[regno].type = UNKNOWN_VALUE;
|
|
regs[regno].id = 0;
|
|
regs[regno].imm = 0;
|
|
}
|
|
|
|
static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
|
|
{
|
|
BUG_ON(regno >= MAX_BPF_REG);
|
|
__mark_reg_unknown_value(regs, regno);
|
|
}
|
|
|
|
static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno)
|
|
{
|
|
regs[regno].min_value = BPF_REGISTER_MIN_RANGE;
|
|
regs[regno].max_value = BPF_REGISTER_MAX_RANGE;
|
|
regs[regno].min_align = 0;
|
|
}
|
|
|
|
static void mark_reg_unknown_value_and_range(struct bpf_reg_state *regs,
|
|
u32 regno)
|
|
{
|
|
mark_reg_unknown_value(regs, regno);
|
|
reset_reg_range_values(regs, regno);
|
|
}
|
|
|
|
enum reg_arg_type {
|
|
SRC_OP, /* register is used as source operand */
|
|
DST_OP, /* register is used as destination operand */
|
|
DST_OP_NO_MARK /* same as above, check only, don't mark */
|
|
};
|
|
|
|
static int check_reg_arg(struct bpf_reg_state *regs, u32 regno,
|
|
enum reg_arg_type t)
|
|
{
|
|
if (regno >= MAX_BPF_REG) {
|
|
verbose("R%d is invalid\n", regno);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (t == SRC_OP) {
|
|
/* check whether register used as source operand can be read */
|
|
if (regs[regno].type == NOT_INIT) {
|
|
verbose("R%d !read_ok\n", regno);
|
|
return -EACCES;
|
|
}
|
|
} else {
|
|
/* check whether register used as dest operand can be written to */
|
|
if (regno == BPF_REG_FP) {
|
|
verbose("frame pointer is read only\n");
|
|
return -EACCES;
|
|
}
|
|
if (t == DST_OP)
|
|
mark_reg_unknown_value(regs, regno);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static bool is_spillable_regtype(enum bpf_reg_type type)
|
|
{
|
|
switch (type) {
|
|
case PTR_TO_MAP_VALUE:
|
|
case PTR_TO_MAP_VALUE_OR_NULL:
|
|
case PTR_TO_MAP_VALUE_ADJ:
|
|
case PTR_TO_STACK:
|
|
case PTR_TO_CTX:
|
|
case PTR_TO_PACKET:
|
|
case PTR_TO_PACKET_END:
|
|
case FRAME_PTR:
|
|
case CONST_PTR_TO_MAP:
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* check_stack_read/write functions track spill/fill of registers,
|
|
* stack boundary and alignment are checked in check_mem_access()
|
|
*/
|
|
static int check_stack_write(struct bpf_verifier_state *state, int off,
|
|
int size, int value_regno)
|
|
{
|
|
int i;
|
|
/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
|
|
* so it's aligned access and [off, off + size) are within stack limits
|
|
*/
|
|
|
|
if (value_regno >= 0 &&
|
|
is_spillable_regtype(state->regs[value_regno].type)) {
|
|
|
|
/* register containing pointer is being spilled into stack */
|
|
if (size != BPF_REG_SIZE) {
|
|
verbose("invalid size of register spill\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
/* save register state */
|
|
state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
|
|
state->regs[value_regno];
|
|
|
|
for (i = 0; i < BPF_REG_SIZE; i++)
|
|
state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
|
|
} else {
|
|
/* regular write of data into stack */
|
|
state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
|
|
(struct bpf_reg_state) {};
|
|
|
|
for (i = 0; i < size; i++)
|
|
state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int check_stack_read(struct bpf_verifier_state *state, int off, int size,
|
|
int value_regno)
|
|
{
|
|
u8 *slot_type;
|
|
int i;
|
|
|
|
slot_type = &state->stack_slot_type[MAX_BPF_STACK + off];
|
|
|
|
if (slot_type[0] == STACK_SPILL) {
|
|
if (size != BPF_REG_SIZE) {
|
|
verbose("invalid size of register spill\n");
|
|
return -EACCES;
|
|
}
|
|
for (i = 1; i < BPF_REG_SIZE; i++) {
|
|
if (slot_type[i] != STACK_SPILL) {
|
|
verbose("corrupted spill memory\n");
|
|
return -EACCES;
|
|
}
|
|
}
|
|
|
|
if (value_regno >= 0)
|
|
/* restore register state from stack */
|
|
state->regs[value_regno] =
|
|
state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE];
|
|
return 0;
|
|
} else {
|
|
for (i = 0; i < size; i++) {
|
|
if (slot_type[i] != STACK_MISC) {
|
|
verbose("invalid read from stack off %d+%d size %d\n",
|
|
off, i, size);
|
|
return -EACCES;
|
|
}
|
|
}
|
|
if (value_regno >= 0)
|
|
/* have read misc data from the stack */
|
|
mark_reg_unknown_value_and_range(state->regs,
|
|
value_regno);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* check read/write into map element returned by bpf_map_lookup_elem() */
|
|
static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
|
|
int size)
|
|
{
|
|
struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
|
|
|
|
if (off < 0 || size <= 0 || off + size > map->value_size) {
|
|
verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
|
|
map->value_size, off, size);
|
|
return -EACCES;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* check read/write into an adjusted map element */
|
|
static int check_map_access_adj(struct bpf_verifier_env *env, u32 regno,
|
|
int off, int size)
|
|
{
|
|
struct bpf_verifier_state *state = &env->cur_state;
|
|
struct bpf_reg_state *reg = &state->regs[regno];
|
|
int err;
|
|
|
|
/* We adjusted the register to this map value, so we
|
|
* need to change off and size to min_value and max_value
|
|
* respectively to make sure our theoretical access will be
|
|
* safe.
|
|
*/
|
|
if (log_level)
|
|
print_verifier_state(state);
|
|
env->varlen_map_value_access = true;
|
|
/* The minimum value is only important with signed
|
|
* comparisons where we can't assume the floor of a
|
|
* value is 0. If we are using signed variables for our
|
|
* index'es we need to make sure that whatever we use
|
|
* will have a set floor within our range.
|
|
*/
|
|
if (reg->min_value < 0) {
|
|
verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
err = check_map_access(env, regno, reg->min_value + off, size);
|
|
if (err) {
|
|
verbose("R%d min value is outside of the array range\n",
|
|
regno);
|
|
return err;
|
|
}
|
|
|
|
/* If we haven't set a max value then we need to bail
|
|
* since we can't be sure we won't do bad things.
|
|
*/
|
|
if (reg->max_value == BPF_REGISTER_MAX_RANGE) {
|
|
verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
return check_map_access(env, regno, reg->max_value + off, size);
|
|
}
|
|
|
|
#define MAX_PACKET_OFF 0xffff
|
|
|
|
static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
|
|
const struct bpf_call_arg_meta *meta,
|
|
enum bpf_access_type t)
|
|
{
|
|
switch (env->prog->type) {
|
|
case BPF_PROG_TYPE_LWT_IN:
|
|
case BPF_PROG_TYPE_LWT_OUT:
|
|
/* dst_input() and dst_output() can't write for now */
|
|
if (t == BPF_WRITE)
|
|
return false;
|
|
/* fallthrough */
|
|
case BPF_PROG_TYPE_SCHED_CLS:
|
|
case BPF_PROG_TYPE_SCHED_ACT:
|
|
case BPF_PROG_TYPE_XDP:
|
|
case BPF_PROG_TYPE_LWT_XMIT:
|
|
if (meta)
|
|
return meta->pkt_access;
|
|
|
|
env->seen_direct_write = true;
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
|
|
int size)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs;
|
|
struct bpf_reg_state *reg = ®s[regno];
|
|
|
|
off += reg->off;
|
|
if (off < 0 || size <= 0 || off + size > reg->range) {
|
|
verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
|
|
off, size, regno, reg->id, reg->off, reg->range);
|
|
return -EACCES;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* check access to 'struct bpf_context' fields */
|
|
static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
|
|
enum bpf_access_type t, enum bpf_reg_type *reg_type)
|
|
{
|
|
struct bpf_insn_access_aux info = {
|
|
.reg_type = *reg_type,
|
|
};
|
|
|
|
/* for analyzer ctx accesses are already validated and converted */
|
|
if (env->analyzer_ops)
|
|
return 0;
|
|
|
|
if (env->prog->aux->ops->is_valid_access &&
|
|
env->prog->aux->ops->is_valid_access(off, size, t, &info)) {
|
|
/* A non zero info.ctx_field_size indicates that this field is a
|
|
* candidate for later verifier transformation to load the whole
|
|
* field and then apply a mask when accessed with a narrower
|
|
* access than actual ctx access size. A zero info.ctx_field_size
|
|
* will only allow for whole field access and rejects any other
|
|
* type of narrower access.
|
|
*/
|
|
env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
|
|
*reg_type = info.reg_type;
|
|
|
|
/* remember the offset of last byte accessed in ctx */
|
|
if (env->prog->aux->max_ctx_offset < off + size)
|
|
env->prog->aux->max_ctx_offset = off + size;
|
|
return 0;
|
|
}
|
|
|
|
verbose("invalid bpf_context access off=%d size=%d\n", off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
|
|
{
|
|
if (env->allow_ptr_leaks)
|
|
return false;
|
|
|
|
switch (env->cur_state.regs[regno].type) {
|
|
case UNKNOWN_VALUE:
|
|
case CONST_IMM:
|
|
return false;
|
|
default:
|
|
return true;
|
|
}
|
|
}
|
|
|
|
static int check_pkt_ptr_alignment(const struct bpf_reg_state *reg,
|
|
int off, int size, bool strict)
|
|
{
|
|
int ip_align;
|
|
int reg_off;
|
|
|
|
/* Byte size accesses are always allowed. */
|
|
if (!strict || size == 1)
|
|
return 0;
|
|
|
|
reg_off = reg->off;
|
|
if (reg->id) {
|
|
if (reg->aux_off_align % size) {
|
|
verbose("Packet access is only %u byte aligned, %d byte access not allowed\n",
|
|
reg->aux_off_align, size);
|
|
return -EACCES;
|
|
}
|
|
reg_off += reg->aux_off;
|
|
}
|
|
|
|
/* For platforms that do not have a Kconfig enabling
|
|
* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
|
|
* NET_IP_ALIGN is universally set to '2'. And on platforms
|
|
* that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
|
|
* to this code only in strict mode where we want to emulate
|
|
* the NET_IP_ALIGN==2 checking. Therefore use an
|
|
* unconditional IP align value of '2'.
|
|
*/
|
|
ip_align = 2;
|
|
if ((ip_align + reg_off + off) % size != 0) {
|
|
verbose("misaligned packet access off %d+%d+%d size %d\n",
|
|
ip_align, reg_off, off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int check_val_ptr_alignment(const struct bpf_reg_state *reg,
|
|
int size, bool strict)
|
|
{
|
|
if (strict && size != 1) {
|
|
verbose("Unknown alignment. Only byte-sized access allowed in value access.\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int check_ptr_alignment(struct bpf_verifier_env *env,
|
|
const struct bpf_reg_state *reg,
|
|
int off, int size)
|
|
{
|
|
bool strict = env->strict_alignment;
|
|
|
|
switch (reg->type) {
|
|
case PTR_TO_PACKET:
|
|
return check_pkt_ptr_alignment(reg, off, size, strict);
|
|
case PTR_TO_MAP_VALUE_ADJ:
|
|
return check_val_ptr_alignment(reg, size, strict);
|
|
default:
|
|
if (off % size != 0) {
|
|
verbose("misaligned access off %d size %d\n",
|
|
off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* check whether memory at (regno + off) is accessible for t = (read | write)
|
|
* if t==write, value_regno is a register which value is stored into memory
|
|
* if t==read, value_regno is a register which will receive the value from memory
|
|
* if t==write && value_regno==-1, some unknown value is stored into memory
|
|
* if t==read && value_regno==-1, don't care what we read from memory
|
|
*/
|
|
static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off,
|
|
int bpf_size, enum bpf_access_type t,
|
|
int value_regno)
|
|
{
|
|
struct bpf_verifier_state *state = &env->cur_state;
|
|
struct bpf_reg_state *reg = &state->regs[regno];
|
|
int size, err = 0;
|
|
|
|
if (reg->type == PTR_TO_STACK)
|
|
off += reg->imm;
|
|
|
|
size = bpf_size_to_bytes(bpf_size);
|
|
if (size < 0)
|
|
return size;
|
|
|
|
err = check_ptr_alignment(env, reg, off, size);
|
|
if (err)
|
|
return err;
|
|
|
|
if (reg->type == PTR_TO_MAP_VALUE ||
|
|
reg->type == PTR_TO_MAP_VALUE_ADJ) {
|
|
if (t == BPF_WRITE && value_regno >= 0 &&
|
|
is_pointer_value(env, value_regno)) {
|
|
verbose("R%d leaks addr into map\n", value_regno);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (reg->type == PTR_TO_MAP_VALUE_ADJ)
|
|
err = check_map_access_adj(env, regno, off, size);
|
|
else
|
|
err = check_map_access(env, regno, off, size);
|
|
if (!err && t == BPF_READ && value_regno >= 0)
|
|
mark_reg_unknown_value_and_range(state->regs,
|
|
value_regno);
|
|
|
|
} else if (reg->type == PTR_TO_CTX) {
|
|
enum bpf_reg_type reg_type = UNKNOWN_VALUE;
|
|
|
|
if (t == BPF_WRITE && value_regno >= 0 &&
|
|
is_pointer_value(env, value_regno)) {
|
|
verbose("R%d leaks addr into ctx\n", value_regno);
|
|
return -EACCES;
|
|
}
|
|
err = check_ctx_access(env, insn_idx, off, size, t, ®_type);
|
|
if (!err && t == BPF_READ && value_regno >= 0) {
|
|
mark_reg_unknown_value_and_range(state->regs,
|
|
value_regno);
|
|
/* note that reg.[id|off|range] == 0 */
|
|
state->regs[value_regno].type = reg_type;
|
|
state->regs[value_regno].aux_off = 0;
|
|
state->regs[value_regno].aux_off_align = 0;
|
|
}
|
|
|
|
} else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) {
|
|
if (off >= 0 || off < -MAX_BPF_STACK) {
|
|
verbose("invalid stack off=%d size=%d\n", off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (env->prog->aux->stack_depth < -off)
|
|
env->prog->aux->stack_depth = -off;
|
|
|
|
if (t == BPF_WRITE) {
|
|
if (!env->allow_ptr_leaks &&
|
|
state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL &&
|
|
size != BPF_REG_SIZE) {
|
|
verbose("attempt to corrupt spilled pointer on stack\n");
|
|
return -EACCES;
|
|
}
|
|
err = check_stack_write(state, off, size, value_regno);
|
|
} else {
|
|
err = check_stack_read(state, off, size, value_regno);
|
|
}
|
|
} else if (state->regs[regno].type == PTR_TO_PACKET) {
|
|
if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
|
|
verbose("cannot write into packet\n");
|
|
return -EACCES;
|
|
}
|
|
if (t == BPF_WRITE && value_regno >= 0 &&
|
|
is_pointer_value(env, value_regno)) {
|
|
verbose("R%d leaks addr into packet\n", value_regno);
|
|
return -EACCES;
|
|
}
|
|
err = check_packet_access(env, regno, off, size);
|
|
if (!err && t == BPF_READ && value_regno >= 0)
|
|
mark_reg_unknown_value_and_range(state->regs,
|
|
value_regno);
|
|
} else {
|
|
verbose("R%d invalid mem access '%s'\n",
|
|
regno, reg_type_str[reg->type]);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks &&
|
|
state->regs[value_regno].type == UNKNOWN_VALUE) {
|
|
/* 1 or 2 byte load zero-extends, determine the number of
|
|
* zero upper bits. Not doing it fo 4 byte load, since
|
|
* such values cannot be added to ptr_to_packet anyway.
|
|
*/
|
|
state->regs[value_regno].imm = 64 - size * 8;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs;
|
|
int err;
|
|
|
|
if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
|
|
insn->imm != 0) {
|
|
verbose("BPF_XADD uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check src1 operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check src2 operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (is_pointer_value(env, insn->src_reg)) {
|
|
verbose("R%d leaks addr into mem\n", insn->src_reg);
|
|
return -EACCES;
|
|
}
|
|
|
|
/* check whether atomic_add can read the memory */
|
|
err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_READ, -1);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check whether atomic_add can write into the same memory */
|
|
return check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_WRITE, -1);
|
|
}
|
|
|
|
/* when register 'regno' is passed into function that will read 'access_size'
|
|
* bytes from that pointer, make sure that it's within stack boundary
|
|
* and all elements of stack are initialized
|
|
*/
|
|
static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
|
|
int access_size, bool zero_size_allowed,
|
|
struct bpf_call_arg_meta *meta)
|
|
{
|
|
struct bpf_verifier_state *state = &env->cur_state;
|
|
struct bpf_reg_state *regs = state->regs;
|
|
int off, i;
|
|
|
|
if (regs[regno].type != PTR_TO_STACK) {
|
|
if (zero_size_allowed && access_size == 0 &&
|
|
regs[regno].type == CONST_IMM &&
|
|
regs[regno].imm == 0)
|
|
return 0;
|
|
|
|
verbose("R%d type=%s expected=%s\n", regno,
|
|
reg_type_str[regs[regno].type],
|
|
reg_type_str[PTR_TO_STACK]);
|
|
return -EACCES;
|
|
}
|
|
|
|
off = regs[regno].imm;
|
|
if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
|
|
access_size <= 0) {
|
|
verbose("invalid stack type R%d off=%d access_size=%d\n",
|
|
regno, off, access_size);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (env->prog->aux->stack_depth < -off)
|
|
env->prog->aux->stack_depth = -off;
|
|
|
|
if (meta && meta->raw_mode) {
|
|
meta->access_size = access_size;
|
|
meta->regno = regno;
|
|
return 0;
|
|
}
|
|
|
|
for (i = 0; i < access_size; i++) {
|
|
if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) {
|
|
verbose("invalid indirect read from stack off %d+%d size %d\n",
|
|
off, i, access_size);
|
|
return -EACCES;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
|
|
int access_size, bool zero_size_allowed,
|
|
struct bpf_call_arg_meta *meta)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs;
|
|
|
|
switch (regs[regno].type) {
|
|
case PTR_TO_PACKET:
|
|
return check_packet_access(env, regno, 0, access_size);
|
|
case PTR_TO_MAP_VALUE:
|
|
return check_map_access(env, regno, 0, access_size);
|
|
case PTR_TO_MAP_VALUE_ADJ:
|
|
return check_map_access_adj(env, regno, 0, access_size);
|
|
default: /* const_imm|ptr_to_stack or invalid ptr */
|
|
return check_stack_boundary(env, regno, access_size,
|
|
zero_size_allowed, meta);
|
|
}
|
|
}
|
|
|
|
static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
|
|
enum bpf_arg_type arg_type,
|
|
struct bpf_call_arg_meta *meta)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno];
|
|
enum bpf_reg_type expected_type, type = reg->type;
|
|
int err = 0;
|
|
|
|
if (arg_type == ARG_DONTCARE)
|
|
return 0;
|
|
|
|
if (type == NOT_INIT) {
|
|
verbose("R%d !read_ok\n", regno);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (arg_type == ARG_ANYTHING) {
|
|
if (is_pointer_value(env, regno)) {
|
|
verbose("R%d leaks addr into helper function\n", regno);
|
|
return -EACCES;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
if (type == PTR_TO_PACKET &&
|
|
!may_access_direct_pkt_data(env, meta, BPF_READ)) {
|
|
verbose("helper access to the packet is not allowed\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
if (arg_type == ARG_PTR_TO_MAP_KEY ||
|
|
arg_type == ARG_PTR_TO_MAP_VALUE) {
|
|
expected_type = PTR_TO_STACK;
|
|
if (type != PTR_TO_PACKET && type != expected_type)
|
|
goto err_type;
|
|
} else if (arg_type == ARG_CONST_SIZE ||
|
|
arg_type == ARG_CONST_SIZE_OR_ZERO) {
|
|
expected_type = CONST_IMM;
|
|
/* One exception. Allow UNKNOWN_VALUE registers when the
|
|
* boundaries are known and don't cause unsafe memory accesses
|
|
*/
|
|
if (type != UNKNOWN_VALUE && type != expected_type)
|
|
goto err_type;
|
|
} else if (arg_type == ARG_CONST_MAP_PTR) {
|
|
expected_type = CONST_PTR_TO_MAP;
|
|
if (type != expected_type)
|
|
goto err_type;
|
|
} else if (arg_type == ARG_PTR_TO_CTX) {
|
|
expected_type = PTR_TO_CTX;
|
|
if (type != expected_type)
|
|
goto err_type;
|
|
} else if (arg_type == ARG_PTR_TO_MEM ||
|
|
arg_type == ARG_PTR_TO_UNINIT_MEM) {
|
|
expected_type = PTR_TO_STACK;
|
|
/* One exception here. In case function allows for NULL to be
|
|
* passed in as argument, it's a CONST_IMM type. Final test
|
|
* happens during stack boundary checking.
|
|
*/
|
|
if (type == CONST_IMM && reg->imm == 0)
|
|
/* final test in check_stack_boundary() */;
|
|
else if (type != PTR_TO_PACKET && type != PTR_TO_MAP_VALUE &&
|
|
type != PTR_TO_MAP_VALUE_ADJ && type != expected_type)
|
|
goto err_type;
|
|
meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM;
|
|
} else {
|
|
verbose("unsupported arg_type %d\n", arg_type);
|
|
return -EFAULT;
|
|
}
|
|
|
|
if (arg_type == ARG_CONST_MAP_PTR) {
|
|
/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
|
|
meta->map_ptr = reg->map_ptr;
|
|
} else if (arg_type == ARG_PTR_TO_MAP_KEY) {
|
|
/* bpf_map_xxx(..., map_ptr, ..., key) call:
|
|
* check that [key, key + map->key_size) are within
|
|
* stack limits and initialized
|
|
*/
|
|
if (!meta->map_ptr) {
|
|
/* in function declaration map_ptr must come before
|
|
* map_key, so that it's verified and known before
|
|
* we have to check map_key here. Otherwise it means
|
|
* that kernel subsystem misconfigured verifier
|
|
*/
|
|
verbose("invalid map_ptr to access map->key\n");
|
|
return -EACCES;
|
|
}
|
|
if (type == PTR_TO_PACKET)
|
|
err = check_packet_access(env, regno, 0,
|
|
meta->map_ptr->key_size);
|
|
else
|
|
err = check_stack_boundary(env, regno,
|
|
meta->map_ptr->key_size,
|
|
false, NULL);
|
|
} else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
|
|
/* bpf_map_xxx(..., map_ptr, ..., value) call:
|
|
* check [value, value + map->value_size) validity
|
|
*/
|
|
if (!meta->map_ptr) {
|
|
/* kernel subsystem misconfigured verifier */
|
|
verbose("invalid map_ptr to access map->value\n");
|
|
return -EACCES;
|
|
}
|
|
if (type == PTR_TO_PACKET)
|
|
err = check_packet_access(env, regno, 0,
|
|
meta->map_ptr->value_size);
|
|
else
|
|
err = check_stack_boundary(env, regno,
|
|
meta->map_ptr->value_size,
|
|
false, NULL);
|
|
} else if (arg_type == ARG_CONST_SIZE ||
|
|
arg_type == ARG_CONST_SIZE_OR_ZERO) {
|
|
bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
|
|
|
|
/* bpf_xxx(..., buf, len) call will access 'len' bytes
|
|
* from stack pointer 'buf'. Check it
|
|
* note: regno == len, regno - 1 == buf
|
|
*/
|
|
if (regno == 0) {
|
|
/* kernel subsystem misconfigured verifier */
|
|
verbose("ARG_CONST_SIZE cannot be first argument\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
/* If the register is UNKNOWN_VALUE, the access check happens
|
|
* using its boundaries. Otherwise, just use its imm
|
|
*/
|
|
if (type == UNKNOWN_VALUE) {
|
|
/* For unprivileged variable accesses, disable raw
|
|
* mode so that the program is required to
|
|
* initialize all the memory that the helper could
|
|
* just partially fill up.
|
|
*/
|
|
meta = NULL;
|
|
|
|
if (reg->min_value < 0) {
|
|
verbose("R%d min value is negative, either use unsigned or 'var &= const'\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (reg->min_value == 0) {
|
|
err = check_helper_mem_access(env, regno - 1, 0,
|
|
zero_size_allowed,
|
|
meta);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
if (reg->max_value == BPF_REGISTER_MAX_RANGE) {
|
|
verbose("R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
err = check_helper_mem_access(env, regno - 1,
|
|
reg->max_value,
|
|
zero_size_allowed, meta);
|
|
if (err)
|
|
return err;
|
|
} else {
|
|
/* register is CONST_IMM */
|
|
err = check_helper_mem_access(env, regno - 1, reg->imm,
|
|
zero_size_allowed, meta);
|
|
}
|
|
}
|
|
|
|
return err;
|
|
err_type:
|
|
verbose("R%d type=%s expected=%s\n", regno,
|
|
reg_type_str[type], reg_type_str[expected_type]);
|
|
return -EACCES;
|
|
}
|
|
|
|
static int check_map_func_compatibility(struct bpf_map *map, int func_id)
|
|
{
|
|
if (!map)
|
|
return 0;
|
|
|
|
/* We need a two way check, first is from map perspective ... */
|
|
switch (map->map_type) {
|
|
case BPF_MAP_TYPE_PROG_ARRAY:
|
|
if (func_id != BPF_FUNC_tail_call)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
|
|
if (func_id != BPF_FUNC_perf_event_read &&
|
|
func_id != BPF_FUNC_perf_event_output)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_STACK_TRACE:
|
|
if (func_id != BPF_FUNC_get_stackid)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_CGROUP_ARRAY:
|
|
if (func_id != BPF_FUNC_skb_under_cgroup &&
|
|
func_id != BPF_FUNC_current_task_under_cgroup)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
|
|
case BPF_MAP_TYPE_HASH_OF_MAPS:
|
|
if (func_id != BPF_FUNC_map_lookup_elem)
|
|
goto error;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
/* ... and second from the function itself. */
|
|
switch (func_id) {
|
|
case BPF_FUNC_tail_call:
|
|
if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_perf_event_read:
|
|
case BPF_FUNC_perf_event_output:
|
|
if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_get_stackid:
|
|
if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_current_task_under_cgroup:
|
|
case BPF_FUNC_skb_under_cgroup:
|
|
if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
|
|
goto error;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
error:
|
|
verbose("cannot pass map_type %d into func %s#%d\n",
|
|
map->map_type, func_id_name(func_id), func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
static int check_raw_mode(const struct bpf_func_proto *fn)
|
|
{
|
|
int count = 0;
|
|
|
|
if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
|
|
return count > 1 ? -EINVAL : 0;
|
|
}
|
|
|
|
static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_verifier_state *state = &env->cur_state;
|
|
struct bpf_reg_state *regs = state->regs, *reg;
|
|
int i;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++)
|
|
if (regs[i].type == PTR_TO_PACKET ||
|
|
regs[i].type == PTR_TO_PACKET_END)
|
|
mark_reg_unknown_value(regs, i);
|
|
|
|
for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
|
|
if (state->stack_slot_type[i] != STACK_SPILL)
|
|
continue;
|
|
reg = &state->spilled_regs[i / BPF_REG_SIZE];
|
|
if (reg->type != PTR_TO_PACKET &&
|
|
reg->type != PTR_TO_PACKET_END)
|
|
continue;
|
|
__mark_reg_unknown_value(state->spilled_regs,
|
|
i / BPF_REG_SIZE);
|
|
}
|
|
}
|
|
|
|
static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
|
|
{
|
|
struct bpf_verifier_state *state = &env->cur_state;
|
|
const struct bpf_func_proto *fn = NULL;
|
|
struct bpf_reg_state *regs = state->regs;
|
|
struct bpf_call_arg_meta meta;
|
|
bool changes_data;
|
|
int i, err;
|
|
|
|
/* find function prototype */
|
|
if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
|
|
verbose("invalid func %s#%d\n", func_id_name(func_id), func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (env->prog->aux->ops->get_func_proto)
|
|
fn = env->prog->aux->ops->get_func_proto(func_id);
|
|
|
|
if (!fn) {
|
|
verbose("unknown func %s#%d\n", func_id_name(func_id), func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* eBPF programs must be GPL compatible to use GPL-ed functions */
|
|
if (!env->prog->gpl_compatible && fn->gpl_only) {
|
|
verbose("cannot call GPL only function from proprietary program\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
changes_data = bpf_helper_changes_pkt_data(fn->func);
|
|
|
|
memset(&meta, 0, sizeof(meta));
|
|
meta.pkt_access = fn->pkt_access;
|
|
|
|
/* We only support one arg being in raw mode at the moment, which
|
|
* is sufficient for the helper functions we have right now.
|
|
*/
|
|
err = check_raw_mode(fn);
|
|
if (err) {
|
|
verbose("kernel subsystem misconfigured func %s#%d\n",
|
|
func_id_name(func_id), func_id);
|
|
return err;
|
|
}
|
|
|
|
/* check args */
|
|
err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta);
|
|
if (err)
|
|
return err;
|
|
|
|
/* Mark slots with STACK_MISC in case of raw mode, stack offset
|
|
* is inferred from register state.
|
|
*/
|
|
for (i = 0; i < meta.access_size; i++) {
|
|
err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
/* reset caller saved regs */
|
|
for (i = 0; i < CALLER_SAVED_REGS; i++)
|
|
mark_reg_not_init(regs, caller_saved[i]);
|
|
|
|
/* update return register */
|
|
if (fn->ret_type == RET_INTEGER) {
|
|
regs[BPF_REG_0].type = UNKNOWN_VALUE;
|
|
} else if (fn->ret_type == RET_VOID) {
|
|
regs[BPF_REG_0].type = NOT_INIT;
|
|
} else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
|
|
struct bpf_insn_aux_data *insn_aux;
|
|
|
|
regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
|
|
regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0;
|
|
/* remember map_ptr, so that check_map_access()
|
|
* can check 'value_size' boundary of memory access
|
|
* to map element returned from bpf_map_lookup_elem()
|
|
*/
|
|
if (meta.map_ptr == NULL) {
|
|
verbose("kernel subsystem misconfigured verifier\n");
|
|
return -EINVAL;
|
|
}
|
|
regs[BPF_REG_0].map_ptr = meta.map_ptr;
|
|
regs[BPF_REG_0].id = ++env->id_gen;
|
|
insn_aux = &env->insn_aux_data[insn_idx];
|
|
if (!insn_aux->map_ptr)
|
|
insn_aux->map_ptr = meta.map_ptr;
|
|
else if (insn_aux->map_ptr != meta.map_ptr)
|
|
insn_aux->map_ptr = BPF_MAP_PTR_POISON;
|
|
} else {
|
|
verbose("unknown return type %d of func %s#%d\n",
|
|
fn->ret_type, func_id_name(func_id), func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
err = check_map_func_compatibility(meta.map_ptr, func_id);
|
|
if (err)
|
|
return err;
|
|
|
|
if (changes_data)
|
|
clear_all_pkt_pointers(env);
|
|
return 0;
|
|
}
|
|
|
|
static int check_packet_ptr_add(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs;
|
|
struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
|
|
struct bpf_reg_state *src_reg = ®s[insn->src_reg];
|
|
struct bpf_reg_state tmp_reg;
|
|
s32 imm;
|
|
|
|
if (BPF_SRC(insn->code) == BPF_K) {
|
|
/* pkt_ptr += imm */
|
|
imm = insn->imm;
|
|
|
|
add_imm:
|
|
if (imm < 0) {
|
|
verbose("addition of negative constant to packet pointer is not allowed\n");
|
|
return -EACCES;
|
|
}
|
|
if (imm >= MAX_PACKET_OFF ||
|
|
imm + dst_reg->off >= MAX_PACKET_OFF) {
|
|
verbose("constant %d is too large to add to packet pointer\n",
|
|
imm);
|
|
return -EACCES;
|
|
}
|
|
/* a constant was added to pkt_ptr.
|
|
* Remember it while keeping the same 'id'
|
|
*/
|
|
dst_reg->off += imm;
|
|
} else {
|
|
bool had_id;
|
|
|
|
if (src_reg->type == PTR_TO_PACKET) {
|
|
/* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */
|
|
tmp_reg = *dst_reg; /* save r7 state */
|
|
*dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */
|
|
src_reg = &tmp_reg; /* pretend it's src_reg state */
|
|
/* if the checks below reject it, the copy won't matter,
|
|
* since we're rejecting the whole program. If all ok,
|
|
* then imm22 state will be added to r7
|
|
* and r7 will be pkt(id=0,off=22,r=62) while
|
|
* r6 will stay as pkt(id=0,off=0,r=62)
|
|
*/
|
|
}
|
|
|
|
if (src_reg->type == CONST_IMM) {
|
|
/* pkt_ptr += reg where reg is known constant */
|
|
imm = src_reg->imm;
|
|
goto add_imm;
|
|
}
|
|
/* disallow pkt_ptr += reg
|
|
* if reg is not uknown_value with guaranteed zero upper bits
|
|
* otherwise pkt_ptr may overflow and addition will become
|
|
* subtraction which is not allowed
|
|
*/
|
|
if (src_reg->type != UNKNOWN_VALUE) {
|
|
verbose("cannot add '%s' to ptr_to_packet\n",
|
|
reg_type_str[src_reg->type]);
|
|
return -EACCES;
|
|
}
|
|
if (src_reg->imm < 48) {
|
|
verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n",
|
|
src_reg->imm);
|
|
return -EACCES;
|
|
}
|
|
|
|
had_id = (dst_reg->id != 0);
|
|
|
|
/* dst_reg stays as pkt_ptr type and since some positive
|
|
* integer value was added to the pointer, increment its 'id'
|
|
*/
|
|
dst_reg->id = ++env->id_gen;
|
|
|
|
/* something was added to pkt_ptr, set range to zero */
|
|
dst_reg->aux_off += dst_reg->off;
|
|
dst_reg->off = 0;
|
|
dst_reg->range = 0;
|
|
if (had_id)
|
|
dst_reg->aux_off_align = min(dst_reg->aux_off_align,
|
|
src_reg->min_align);
|
|
else
|
|
dst_reg->aux_off_align = src_reg->min_align;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs;
|
|
struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
|
|
u8 opcode = BPF_OP(insn->code);
|
|
s64 imm_log2;
|
|
|
|
/* for type == UNKNOWN_VALUE:
|
|
* imm > 0 -> number of zero upper bits
|
|
* imm == 0 -> don't track which is the same as all bits can be non-zero
|
|
*/
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
struct bpf_reg_state *src_reg = ®s[insn->src_reg];
|
|
|
|
if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 &&
|
|
dst_reg->imm && opcode == BPF_ADD) {
|
|
/* dreg += sreg
|
|
* where both have zero upper bits. Adding them
|
|
* can only result making one more bit non-zero
|
|
* in the larger value.
|
|
* Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
|
|
* 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
|
|
*/
|
|
dst_reg->imm = min(dst_reg->imm, src_reg->imm);
|
|
dst_reg->imm--;
|
|
return 0;
|
|
}
|
|
if (src_reg->type == CONST_IMM && src_reg->imm > 0 &&
|
|
dst_reg->imm && opcode == BPF_ADD) {
|
|
/* dreg += sreg
|
|
* where dreg has zero upper bits and sreg is const.
|
|
* Adding them can only result making one more bit
|
|
* non-zero in the larger value.
|
|
*/
|
|
imm_log2 = __ilog2_u64((long long)src_reg->imm);
|
|
dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
|
|
dst_reg->imm--;
|
|
return 0;
|
|
}
|
|
/* all other cases non supported yet, just mark dst_reg */
|
|
dst_reg->imm = 0;
|
|
return 0;
|
|
}
|
|
|
|
/* sign extend 32-bit imm into 64-bit to make sure that
|
|
* negative values occupy bit 63. Note ilog2() would have
|
|
* been incorrect, since sizeof(insn->imm) == 4
|
|
*/
|
|
imm_log2 = __ilog2_u64((long long)insn->imm);
|
|
|
|
if (dst_reg->imm && opcode == BPF_LSH) {
|
|
/* reg <<= imm
|
|
* if reg was a result of 2 byte load, then its imm == 48
|
|
* which means that upper 48 bits are zero and shifting this reg
|
|
* left by 4 would mean that upper 44 bits are still zero
|
|
*/
|
|
dst_reg->imm -= insn->imm;
|
|
} else if (dst_reg->imm && opcode == BPF_MUL) {
|
|
/* reg *= imm
|
|
* if multiplying by 14 subtract 4
|
|
* This is conservative calculation of upper zero bits.
|
|
* It's not trying to special case insn->imm == 1 or 0 cases
|
|
*/
|
|
dst_reg->imm -= imm_log2 + 1;
|
|
} else if (opcode == BPF_AND) {
|
|
/* reg &= imm */
|
|
dst_reg->imm = 63 - imm_log2;
|
|
} else if (dst_reg->imm && opcode == BPF_ADD) {
|
|
/* reg += imm */
|
|
dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
|
|
dst_reg->imm--;
|
|
} else if (opcode == BPF_RSH) {
|
|
/* reg >>= imm
|
|
* which means that after right shift, upper bits will be zero
|
|
* note that verifier already checked that
|
|
* 0 <= imm < 64 for shift insn
|
|
*/
|
|
dst_reg->imm += insn->imm;
|
|
if (unlikely(dst_reg->imm > 64))
|
|
/* some dumb code did:
|
|
* r2 = *(u32 *)mem;
|
|
* r2 >>= 32;
|
|
* and all bits are zero now */
|
|
dst_reg->imm = 64;
|
|
} else {
|
|
/* all other alu ops, means that we don't know what will
|
|
* happen to the value, mark it with unknown number of zero bits
|
|
*/
|
|
dst_reg->imm = 0;
|
|
}
|
|
|
|
if (dst_reg->imm < 0) {
|
|
/* all 64 bits of the register can contain non-zero bits
|
|
* and such value cannot be added to ptr_to_packet, since it
|
|
* may overflow, mark it as unknown to avoid further eval
|
|
*/
|
|
dst_reg->imm = 0;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int evaluate_reg_imm_alu_unknown(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs;
|
|
struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
|
|
struct bpf_reg_state *src_reg = ®s[insn->src_reg];
|
|
u8 opcode = BPF_OP(insn->code);
|
|
s64 imm_log2 = __ilog2_u64((long long)dst_reg->imm);
|
|
|
|
/* BPF_X code with src_reg->type UNKNOWN_VALUE here. */
|
|
if (src_reg->imm > 0 && dst_reg->imm) {
|
|
switch (opcode) {
|
|
case BPF_ADD:
|
|
/* dreg += sreg
|
|
* where both have zero upper bits. Adding them
|
|
* can only result making one more bit non-zero
|
|
* in the larger value.
|
|
* Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
|
|
* 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
|
|
*/
|
|
dst_reg->imm = min(src_reg->imm, 63 - imm_log2);
|
|
dst_reg->imm--;
|
|
break;
|
|
case BPF_AND:
|
|
/* dreg &= sreg
|
|
* AND can not extend zero bits only shrink
|
|
* Ex. 0x00..00ffffff
|
|
* & 0x0f..ffffffff
|
|
* ----------------
|
|
* 0x00..00ffffff
|
|
*/
|
|
dst_reg->imm = max(src_reg->imm, 63 - imm_log2);
|
|
break;
|
|
case BPF_OR:
|
|
/* dreg |= sreg
|
|
* OR can only extend zero bits
|
|
* Ex. 0x00..00ffffff
|
|
* | 0x0f..ffffffff
|
|
* ----------------
|
|
* 0x0f..00ffffff
|
|
*/
|
|
dst_reg->imm = min(src_reg->imm, 63 - imm_log2);
|
|
break;
|
|
case BPF_SUB:
|
|
case BPF_MUL:
|
|
case BPF_RSH:
|
|
case BPF_LSH:
|
|
/* These may be flushed out later */
|
|
default:
|
|
mark_reg_unknown_value(regs, insn->dst_reg);
|
|
}
|
|
} else {
|
|
mark_reg_unknown_value(regs, insn->dst_reg);
|
|
}
|
|
|
|
dst_reg->type = UNKNOWN_VALUE;
|
|
return 0;
|
|
}
|
|
|
|
static int evaluate_reg_imm_alu(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs;
|
|
struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
|
|
struct bpf_reg_state *src_reg = ®s[insn->src_reg];
|
|
u8 opcode = BPF_OP(insn->code);
|
|
u64 dst_imm = dst_reg->imm;
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X && src_reg->type == UNKNOWN_VALUE)
|
|
return evaluate_reg_imm_alu_unknown(env, insn);
|
|
|
|
/* dst_reg->type == CONST_IMM here. Simulate execution of insns
|
|
* containing ALU ops. Don't care about overflow or negative
|
|
* values, just add/sub/... them; registers are in u64.
|
|
*/
|
|
if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) {
|
|
dst_imm += insn->imm;
|
|
} else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X &&
|
|
src_reg->type == CONST_IMM) {
|
|
dst_imm += src_reg->imm;
|
|
} else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_K) {
|
|
dst_imm -= insn->imm;
|
|
} else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_X &&
|
|
src_reg->type == CONST_IMM) {
|
|
dst_imm -= src_reg->imm;
|
|
} else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_K) {
|
|
dst_imm *= insn->imm;
|
|
} else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_X &&
|
|
src_reg->type == CONST_IMM) {
|
|
dst_imm *= src_reg->imm;
|
|
} else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_K) {
|
|
dst_imm |= insn->imm;
|
|
} else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_X &&
|
|
src_reg->type == CONST_IMM) {
|
|
dst_imm |= src_reg->imm;
|
|
} else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_K) {
|
|
dst_imm &= insn->imm;
|
|
} else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_X &&
|
|
src_reg->type == CONST_IMM) {
|
|
dst_imm &= src_reg->imm;
|
|
} else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_K) {
|
|
dst_imm >>= insn->imm;
|
|
} else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_X &&
|
|
src_reg->type == CONST_IMM) {
|
|
dst_imm >>= src_reg->imm;
|
|
} else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_K) {
|
|
dst_imm <<= insn->imm;
|
|
} else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_X &&
|
|
src_reg->type == CONST_IMM) {
|
|
dst_imm <<= src_reg->imm;
|
|
} else {
|
|
mark_reg_unknown_value(regs, insn->dst_reg);
|
|
goto out;
|
|
}
|
|
|
|
dst_reg->imm = dst_imm;
|
|
out:
|
|
return 0;
|
|
}
|
|
|
|
static void check_reg_overflow(struct bpf_reg_state *reg)
|
|
{
|
|
if (reg->max_value > BPF_REGISTER_MAX_RANGE)
|
|
reg->max_value = BPF_REGISTER_MAX_RANGE;
|
|
if (reg->min_value < BPF_REGISTER_MIN_RANGE ||
|
|
reg->min_value > BPF_REGISTER_MAX_RANGE)
|
|
reg->min_value = BPF_REGISTER_MIN_RANGE;
|
|
}
|
|
|
|
static u32 calc_align(u32 imm)
|
|
{
|
|
if (!imm)
|
|
return 1U << 31;
|
|
return imm - ((imm - 1) & imm);
|
|
}
|
|
|
|
static void adjust_reg_min_max_vals(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
|
|
s64 min_val = BPF_REGISTER_MIN_RANGE;
|
|
u64 max_val = BPF_REGISTER_MAX_RANGE;
|
|
u8 opcode = BPF_OP(insn->code);
|
|
u32 dst_align, src_align;
|
|
|
|
dst_reg = ®s[insn->dst_reg];
|
|
src_align = 0;
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
check_reg_overflow(®s[insn->src_reg]);
|
|
min_val = regs[insn->src_reg].min_value;
|
|
max_val = regs[insn->src_reg].max_value;
|
|
|
|
/* If the source register is a random pointer then the
|
|
* min_value/max_value values represent the range of the known
|
|
* accesses into that value, not the actual min/max value of the
|
|
* register itself. In this case we have to reset the reg range
|
|
* values so we know it is not safe to look at.
|
|
*/
|
|
if (regs[insn->src_reg].type != CONST_IMM &&
|
|
regs[insn->src_reg].type != UNKNOWN_VALUE) {
|
|
min_val = BPF_REGISTER_MIN_RANGE;
|
|
max_val = BPF_REGISTER_MAX_RANGE;
|
|
src_align = 0;
|
|
} else {
|
|
src_align = regs[insn->src_reg].min_align;
|
|
}
|
|
} else if (insn->imm < BPF_REGISTER_MAX_RANGE &&
|
|
(s64)insn->imm > BPF_REGISTER_MIN_RANGE) {
|
|
min_val = max_val = insn->imm;
|
|
src_align = calc_align(insn->imm);
|
|
}
|
|
|
|
dst_align = dst_reg->min_align;
|
|
|
|
/* We don't know anything about what was done to this register, mark it
|
|
* as unknown.
|
|
*/
|
|
if (min_val == BPF_REGISTER_MIN_RANGE &&
|
|
max_val == BPF_REGISTER_MAX_RANGE) {
|
|
reset_reg_range_values(regs, insn->dst_reg);
|
|
return;
|
|
}
|
|
|
|
/* If one of our values was at the end of our ranges then we can't just
|
|
* do our normal operations to the register, we need to set the values
|
|
* to the min/max since they are undefined.
|
|
*/
|
|
if (min_val == BPF_REGISTER_MIN_RANGE)
|
|
dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
|
|
if (max_val == BPF_REGISTER_MAX_RANGE)
|
|
dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
|
|
|
|
switch (opcode) {
|
|
case BPF_ADD:
|
|
if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
|
|
dst_reg->min_value += min_val;
|
|
if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
|
|
dst_reg->max_value += max_val;
|
|
dst_reg->min_align = min(src_align, dst_align);
|
|
break;
|
|
case BPF_SUB:
|
|
if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
|
|
dst_reg->min_value -= min_val;
|
|
if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
|
|
dst_reg->max_value -= max_val;
|
|
dst_reg->min_align = min(src_align, dst_align);
|
|
break;
|
|
case BPF_MUL:
|
|
if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
|
|
dst_reg->min_value *= min_val;
|
|
if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
|
|
dst_reg->max_value *= max_val;
|
|
dst_reg->min_align = max(src_align, dst_align);
|
|
break;
|
|
case BPF_AND:
|
|
/* Disallow AND'ing of negative numbers, ain't nobody got time
|
|
* for that. Otherwise the minimum is 0 and the max is the max
|
|
* value we could AND against.
|
|
*/
|
|
if (min_val < 0)
|
|
dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
|
|
else
|
|
dst_reg->min_value = 0;
|
|
dst_reg->max_value = max_val;
|
|
dst_reg->min_align = max(src_align, dst_align);
|
|
break;
|
|
case BPF_LSH:
|
|
/* Gotta have special overflow logic here, if we're shifting
|
|
* more than MAX_RANGE then just assume we have an invalid
|
|
* range.
|
|
*/
|
|
if (min_val > ilog2(BPF_REGISTER_MAX_RANGE)) {
|
|
dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
|
|
dst_reg->min_align = 1;
|
|
} else {
|
|
if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
|
|
dst_reg->min_value <<= min_val;
|
|
if (!dst_reg->min_align)
|
|
dst_reg->min_align = 1;
|
|
dst_reg->min_align <<= min_val;
|
|
}
|
|
if (max_val > ilog2(BPF_REGISTER_MAX_RANGE))
|
|
dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
|
|
else if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
|
|
dst_reg->max_value <<= max_val;
|
|
break;
|
|
case BPF_RSH:
|
|
/* RSH by a negative number is undefined, and the BPF_RSH is an
|
|
* unsigned shift, so make the appropriate casts.
|
|
*/
|
|
if (min_val < 0 || dst_reg->min_value < 0) {
|
|
dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
|
|
} else {
|
|
dst_reg->min_value =
|
|
(u64)(dst_reg->min_value) >> min_val;
|
|
}
|
|
if (min_val < 0) {
|
|
dst_reg->min_align = 1;
|
|
} else {
|
|
dst_reg->min_align >>= (u64) min_val;
|
|
if (!dst_reg->min_align)
|
|
dst_reg->min_align = 1;
|
|
}
|
|
if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
|
|
dst_reg->max_value >>= max_val;
|
|
break;
|
|
default:
|
|
reset_reg_range_values(regs, insn->dst_reg);
|
|
break;
|
|
}
|
|
|
|
check_reg_overflow(dst_reg);
|
|
}
|
|
|
|
/* check validity of 32-bit and 64-bit arithmetic operations */
|
|
static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
|
|
u8 opcode = BPF_OP(insn->code);
|
|
int err;
|
|
|
|
if (opcode == BPF_END || opcode == BPF_NEG) {
|
|
if (opcode == BPF_NEG) {
|
|
if (BPF_SRC(insn->code) != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->off != 0 || insn->imm != 0) {
|
|
verbose("BPF_NEG uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
|
|
(insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
|
|
verbose("BPF_END uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check src operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (is_pointer_value(env, insn->dst_reg)) {
|
|
verbose("R%d pointer arithmetic prohibited\n",
|
|
insn->dst_reg);
|
|
return -EACCES;
|
|
}
|
|
|
|
/* check dest operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (opcode == BPF_MOV) {
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (insn->imm != 0 || insn->off != 0) {
|
|
verbose("BPF_MOV uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check src operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
|
|
verbose("BPF_MOV uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check dest operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
/* we are setting our register to something new, we need to
|
|
* reset its range values.
|
|
*/
|
|
reset_reg_range_values(regs, insn->dst_reg);
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (BPF_CLASS(insn->code) == BPF_ALU64) {
|
|
/* case: R1 = R2
|
|
* copy register state to dest reg
|
|
*/
|
|
regs[insn->dst_reg] = regs[insn->src_reg];
|
|
} else {
|
|
if (is_pointer_value(env, insn->src_reg)) {
|
|
verbose("R%d partial copy of pointer\n",
|
|
insn->src_reg);
|
|
return -EACCES;
|
|
}
|
|
mark_reg_unknown_value(regs, insn->dst_reg);
|
|
}
|
|
} else {
|
|
/* case: R = imm
|
|
* remember the value we stored into this reg
|
|
*/
|
|
regs[insn->dst_reg].type = CONST_IMM;
|
|
regs[insn->dst_reg].imm = insn->imm;
|
|
regs[insn->dst_reg].id = 0;
|
|
regs[insn->dst_reg].max_value = insn->imm;
|
|
regs[insn->dst_reg].min_value = insn->imm;
|
|
regs[insn->dst_reg].min_align = calc_align(insn->imm);
|
|
}
|
|
|
|
} else if (opcode > BPF_END) {
|
|
verbose("invalid BPF_ALU opcode %x\n", opcode);
|
|
return -EINVAL;
|
|
|
|
} else { /* all other ALU ops: and, sub, xor, add, ... */
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (insn->imm != 0 || insn->off != 0) {
|
|
verbose("BPF_ALU uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
/* check src1 operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
|
|
verbose("BPF_ALU uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check src2 operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
|
|
BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
|
|
verbose("div by zero\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if ((opcode == BPF_LSH || opcode == BPF_RSH ||
|
|
opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
|
|
int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
|
|
|
|
if (insn->imm < 0 || insn->imm >= size) {
|
|
verbose("invalid shift %d\n", insn->imm);
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check dest operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
|
|
if (err)
|
|
return err;
|
|
|
|
dst_reg = ®s[insn->dst_reg];
|
|
|
|
/* first we want to adjust our ranges. */
|
|
adjust_reg_min_max_vals(env, insn);
|
|
|
|
/* pattern match 'bpf_add Rx, imm' instruction */
|
|
if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
|
|
dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) {
|
|
dst_reg->type = PTR_TO_STACK;
|
|
dst_reg->imm = insn->imm;
|
|
return 0;
|
|
} else if (opcode == BPF_ADD &&
|
|
BPF_CLASS(insn->code) == BPF_ALU64 &&
|
|
dst_reg->type == PTR_TO_STACK &&
|
|
((BPF_SRC(insn->code) == BPF_X &&
|
|
regs[insn->src_reg].type == CONST_IMM) ||
|
|
BPF_SRC(insn->code) == BPF_K)) {
|
|
if (BPF_SRC(insn->code) == BPF_X)
|
|
dst_reg->imm += regs[insn->src_reg].imm;
|
|
else
|
|
dst_reg->imm += insn->imm;
|
|
return 0;
|
|
} else if (opcode == BPF_ADD &&
|
|
BPF_CLASS(insn->code) == BPF_ALU64 &&
|
|
(dst_reg->type == PTR_TO_PACKET ||
|
|
(BPF_SRC(insn->code) == BPF_X &&
|
|
regs[insn->src_reg].type == PTR_TO_PACKET))) {
|
|
/* ptr_to_packet += K|X */
|
|
return check_packet_ptr_add(env, insn);
|
|
} else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
|
|
dst_reg->type == UNKNOWN_VALUE &&
|
|
env->allow_ptr_leaks) {
|
|
/* unknown += K|X */
|
|
return evaluate_reg_alu(env, insn);
|
|
} else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
|
|
dst_reg->type == CONST_IMM &&
|
|
env->allow_ptr_leaks) {
|
|
/* reg_imm += K|X */
|
|
return evaluate_reg_imm_alu(env, insn);
|
|
} else if (is_pointer_value(env, insn->dst_reg)) {
|
|
verbose("R%d pointer arithmetic prohibited\n",
|
|
insn->dst_reg);
|
|
return -EACCES;
|
|
} else if (BPF_SRC(insn->code) == BPF_X &&
|
|
is_pointer_value(env, insn->src_reg)) {
|
|
verbose("R%d pointer arithmetic prohibited\n",
|
|
insn->src_reg);
|
|
return -EACCES;
|
|
}
|
|
|
|
/* If we did pointer math on a map value then just set it to our
|
|
* PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or
|
|
* loads to this register appropriately, otherwise just mark the
|
|
* register as unknown.
|
|
*/
|
|
if (env->allow_ptr_leaks &&
|
|
BPF_CLASS(insn->code) == BPF_ALU64 && opcode == BPF_ADD &&
|
|
(dst_reg->type == PTR_TO_MAP_VALUE ||
|
|
dst_reg->type == PTR_TO_MAP_VALUE_ADJ))
|
|
dst_reg->type = PTR_TO_MAP_VALUE_ADJ;
|
|
else
|
|
mark_reg_unknown_value(regs, insn->dst_reg);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void find_good_pkt_pointers(struct bpf_verifier_state *state,
|
|
struct bpf_reg_state *dst_reg)
|
|
{
|
|
struct bpf_reg_state *regs = state->regs, *reg;
|
|
int i;
|
|
|
|
/* LLVM can generate two kind of checks:
|
|
*
|
|
* Type 1:
|
|
*
|
|
* r2 = r3;
|
|
* r2 += 8;
|
|
* if (r2 > pkt_end) goto <handle exception>
|
|
* <access okay>
|
|
*
|
|
* Where:
|
|
* r2 == dst_reg, pkt_end == src_reg
|
|
* r2=pkt(id=n,off=8,r=0)
|
|
* r3=pkt(id=n,off=0,r=0)
|
|
*
|
|
* Type 2:
|
|
*
|
|
* r2 = r3;
|
|
* r2 += 8;
|
|
* if (pkt_end >= r2) goto <access okay>
|
|
* <handle exception>
|
|
*
|
|
* Where:
|
|
* pkt_end == dst_reg, r2 == src_reg
|
|
* r2=pkt(id=n,off=8,r=0)
|
|
* r3=pkt(id=n,off=0,r=0)
|
|
*
|
|
* Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
|
|
* so that range of bytes [r3, r3 + 8) is safe to access.
|
|
*/
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++)
|
|
if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id)
|
|
/* keep the maximum range already checked */
|
|
regs[i].range = max(regs[i].range, dst_reg->off);
|
|
|
|
for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
|
|
if (state->stack_slot_type[i] != STACK_SPILL)
|
|
continue;
|
|
reg = &state->spilled_regs[i / BPF_REG_SIZE];
|
|
if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id)
|
|
reg->range = max(reg->range, dst_reg->off);
|
|
}
|
|
}
|
|
|
|
/* Adjusts the register min/max values in the case that the dst_reg is the
|
|
* variable register that we are working on, and src_reg is a constant or we're
|
|
* simply doing a BPF_K check.
|
|
*/
|
|
static void reg_set_min_max(struct bpf_reg_state *true_reg,
|
|
struct bpf_reg_state *false_reg, u64 val,
|
|
u8 opcode)
|
|
{
|
|
switch (opcode) {
|
|
case BPF_JEQ:
|
|
/* If this is false then we know nothing Jon Snow, but if it is
|
|
* true then we know for sure.
|
|
*/
|
|
true_reg->max_value = true_reg->min_value = val;
|
|
break;
|
|
case BPF_JNE:
|
|
/* If this is true we know nothing Jon Snow, but if it is false
|
|
* we know the value for sure;
|
|
*/
|
|
false_reg->max_value = false_reg->min_value = val;
|
|
break;
|
|
case BPF_JGT:
|
|
/* Unsigned comparison, the minimum value is 0. */
|
|
false_reg->min_value = 0;
|
|
/* fallthrough */
|
|
case BPF_JSGT:
|
|
/* If this is false then we know the maximum val is val,
|
|
* otherwise we know the min val is val+1.
|
|
*/
|
|
false_reg->max_value = val;
|
|
true_reg->min_value = val + 1;
|
|
break;
|
|
case BPF_JGE:
|
|
/* Unsigned comparison, the minimum value is 0. */
|
|
false_reg->min_value = 0;
|
|
/* fallthrough */
|
|
case BPF_JSGE:
|
|
/* If this is false then we know the maximum value is val - 1,
|
|
* otherwise we know the mimimum value is val.
|
|
*/
|
|
false_reg->max_value = val - 1;
|
|
true_reg->min_value = val;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
check_reg_overflow(false_reg);
|
|
check_reg_overflow(true_reg);
|
|
}
|
|
|
|
/* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg
|
|
* is the variable reg.
|
|
*/
|
|
static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
|
|
struct bpf_reg_state *false_reg, u64 val,
|
|
u8 opcode)
|
|
{
|
|
switch (opcode) {
|
|
case BPF_JEQ:
|
|
/* If this is false then we know nothing Jon Snow, but if it is
|
|
* true then we know for sure.
|
|
*/
|
|
true_reg->max_value = true_reg->min_value = val;
|
|
break;
|
|
case BPF_JNE:
|
|
/* If this is true we know nothing Jon Snow, but if it is false
|
|
* we know the value for sure;
|
|
*/
|
|
false_reg->max_value = false_reg->min_value = val;
|
|
break;
|
|
case BPF_JGT:
|
|
/* Unsigned comparison, the minimum value is 0. */
|
|
true_reg->min_value = 0;
|
|
/* fallthrough */
|
|
case BPF_JSGT:
|
|
/*
|
|
* If this is false, then the val is <= the register, if it is
|
|
* true the register <= to the val.
|
|
*/
|
|
false_reg->min_value = val;
|
|
true_reg->max_value = val - 1;
|
|
break;
|
|
case BPF_JGE:
|
|
/* Unsigned comparison, the minimum value is 0. */
|
|
true_reg->min_value = 0;
|
|
/* fallthrough */
|
|
case BPF_JSGE:
|
|
/* If this is false then constant < register, if it is true then
|
|
* the register < constant.
|
|
*/
|
|
false_reg->min_value = val + 1;
|
|
true_reg->max_value = val;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
check_reg_overflow(false_reg);
|
|
check_reg_overflow(true_reg);
|
|
}
|
|
|
|
static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id,
|
|
enum bpf_reg_type type)
|
|
{
|
|
struct bpf_reg_state *reg = ®s[regno];
|
|
|
|
if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) {
|
|
if (type == UNKNOWN_VALUE) {
|
|
__mark_reg_unknown_value(regs, regno);
|
|
} else if (reg->map_ptr->inner_map_meta) {
|
|
reg->type = CONST_PTR_TO_MAP;
|
|
reg->map_ptr = reg->map_ptr->inner_map_meta;
|
|
} else {
|
|
reg->type = type;
|
|
}
|
|
/* We don't need id from this point onwards anymore, thus we
|
|
* should better reset it, so that state pruning has chances
|
|
* to take effect.
|
|
*/
|
|
reg->id = 0;
|
|
}
|
|
}
|
|
|
|
/* The logic is similar to find_good_pkt_pointers(), both could eventually
|
|
* be folded together at some point.
|
|
*/
|
|
static void mark_map_regs(struct bpf_verifier_state *state, u32 regno,
|
|
enum bpf_reg_type type)
|
|
{
|
|
struct bpf_reg_state *regs = state->regs;
|
|
u32 id = regs[regno].id;
|
|
int i;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++)
|
|
mark_map_reg(regs, i, id, type);
|
|
|
|
for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
|
|
if (state->stack_slot_type[i] != STACK_SPILL)
|
|
continue;
|
|
mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, type);
|
|
}
|
|
}
|
|
|
|
static int check_cond_jmp_op(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn, int *insn_idx)
|
|
{
|
|
struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state;
|
|
struct bpf_reg_state *regs = this_branch->regs, *dst_reg;
|
|
u8 opcode = BPF_OP(insn->code);
|
|
int err;
|
|
|
|
if (opcode > BPF_EXIT) {
|
|
verbose("invalid BPF_JMP opcode %x\n", opcode);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (insn->imm != 0) {
|
|
verbose("BPF_JMP uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check src1 operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (is_pointer_value(env, insn->src_reg)) {
|
|
verbose("R%d pointer comparison prohibited\n",
|
|
insn->src_reg);
|
|
return -EACCES;
|
|
}
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0) {
|
|
verbose("BPF_JMP uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check src2 operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
dst_reg = ®s[insn->dst_reg];
|
|
|
|
/* detect if R == 0 where R was initialized to zero earlier */
|
|
if (BPF_SRC(insn->code) == BPF_K &&
|
|
(opcode == BPF_JEQ || opcode == BPF_JNE) &&
|
|
dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) {
|
|
if (opcode == BPF_JEQ) {
|
|
/* if (imm == imm) goto pc+off;
|
|
* only follow the goto, ignore fall-through
|
|
*/
|
|
*insn_idx += insn->off;
|
|
return 0;
|
|
} else {
|
|
/* if (imm != imm) goto pc+off;
|
|
* only follow fall-through branch, since
|
|
* that's where the program will go
|
|
*/
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
|
|
if (!other_branch)
|
|
return -EFAULT;
|
|
|
|
/* detect if we are comparing against a constant value so we can adjust
|
|
* our min/max values for our dst register.
|
|
*/
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (regs[insn->src_reg].type == CONST_IMM)
|
|
reg_set_min_max(&other_branch->regs[insn->dst_reg],
|
|
dst_reg, regs[insn->src_reg].imm,
|
|
opcode);
|
|
else if (dst_reg->type == CONST_IMM)
|
|
reg_set_min_max_inv(&other_branch->regs[insn->src_reg],
|
|
®s[insn->src_reg], dst_reg->imm,
|
|
opcode);
|
|
} else {
|
|
reg_set_min_max(&other_branch->regs[insn->dst_reg],
|
|
dst_reg, insn->imm, opcode);
|
|
}
|
|
|
|
/* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
|
|
if (BPF_SRC(insn->code) == BPF_K &&
|
|
insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
|
|
dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
|
|
/* Mark all identical map registers in each branch as either
|
|
* safe or unknown depending R == 0 or R != 0 conditional.
|
|
*/
|
|
mark_map_regs(this_branch, insn->dst_reg,
|
|
opcode == BPF_JEQ ? PTR_TO_MAP_VALUE : UNKNOWN_VALUE);
|
|
mark_map_regs(other_branch, insn->dst_reg,
|
|
opcode == BPF_JEQ ? UNKNOWN_VALUE : PTR_TO_MAP_VALUE);
|
|
} else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT &&
|
|
dst_reg->type == PTR_TO_PACKET &&
|
|
regs[insn->src_reg].type == PTR_TO_PACKET_END) {
|
|
find_good_pkt_pointers(this_branch, dst_reg);
|
|
} else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE &&
|
|
dst_reg->type == PTR_TO_PACKET_END &&
|
|
regs[insn->src_reg].type == PTR_TO_PACKET) {
|
|
find_good_pkt_pointers(other_branch, ®s[insn->src_reg]);
|
|
} else if (is_pointer_value(env, insn->dst_reg)) {
|
|
verbose("R%d pointer comparison prohibited\n", insn->dst_reg);
|
|
return -EACCES;
|
|
}
|
|
if (log_level)
|
|
print_verifier_state(this_branch);
|
|
return 0;
|
|
}
|
|
|
|
/* return the map pointer stored inside BPF_LD_IMM64 instruction */
|
|
static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
|
|
{
|
|
u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
|
|
|
|
return (struct bpf_map *) (unsigned long) imm64;
|
|
}
|
|
|
|
/* verify BPF_LD_IMM64 instruction */
|
|
static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs;
|
|
int err;
|
|
|
|
if (BPF_SIZE(insn->code) != BPF_DW) {
|
|
verbose("invalid BPF_LD_IMM insn\n");
|
|
return -EINVAL;
|
|
}
|
|
if (insn->off != 0) {
|
|
verbose("BPF_LD_IMM64 uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (insn->src_reg == 0) {
|
|
u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
|
|
|
|
regs[insn->dst_reg].type = CONST_IMM;
|
|
regs[insn->dst_reg].imm = imm;
|
|
regs[insn->dst_reg].id = 0;
|
|
return 0;
|
|
}
|
|
|
|
/* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
|
|
BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
|
|
|
|
regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
|
|
regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
|
|
return 0;
|
|
}
|
|
|
|
static bool may_access_skb(enum bpf_prog_type type)
|
|
{
|
|
switch (type) {
|
|
case BPF_PROG_TYPE_SOCKET_FILTER:
|
|
case BPF_PROG_TYPE_SCHED_CLS:
|
|
case BPF_PROG_TYPE_SCHED_ACT:
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* verify safety of LD_ABS|LD_IND instructions:
|
|
* - they can only appear in the programs where ctx == skb
|
|
* - since they are wrappers of function calls, they scratch R1-R5 registers,
|
|
* preserve R6-R9, and store return value into R0
|
|
*
|
|
* Implicit input:
|
|
* ctx == skb == R6 == CTX
|
|
*
|
|
* Explicit input:
|
|
* SRC == any register
|
|
* IMM == 32-bit immediate
|
|
*
|
|
* Output:
|
|
* R0 - 8/16/32-bit skb data converted to cpu endianness
|
|
*/
|
|
static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = env->cur_state.regs;
|
|
u8 mode = BPF_MODE(insn->code);
|
|
int i, err;
|
|
|
|
if (!may_access_skb(env->prog->type)) {
|
|
verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
|
|
BPF_SIZE(insn->code) == BPF_DW ||
|
|
(mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
|
|
verbose("BPF_LD_[ABS|IND] uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check whether implicit source operand (register R6) is readable */
|
|
err = check_reg_arg(regs, BPF_REG_6, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (regs[BPF_REG_6].type != PTR_TO_CTX) {
|
|
verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (mode == BPF_IND) {
|
|
/* check explicit source operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
/* reset caller saved regs to unreadable */
|
|
for (i = 0; i < CALLER_SAVED_REGS; i++)
|
|
mark_reg_not_init(regs, caller_saved[i]);
|
|
|
|
/* mark destination R0 register as readable, since it contains
|
|
* the value fetched from the packet
|
|
*/
|
|
regs[BPF_REG_0].type = UNKNOWN_VALUE;
|
|
return 0;
|
|
}
|
|
|
|
/* non-recursive DFS pseudo code
|
|
* 1 procedure DFS-iterative(G,v):
|
|
* 2 label v as discovered
|
|
* 3 let S be a stack
|
|
* 4 S.push(v)
|
|
* 5 while S is not empty
|
|
* 6 t <- S.pop()
|
|
* 7 if t is what we're looking for:
|
|
* 8 return t
|
|
* 9 for all edges e in G.adjacentEdges(t) do
|
|
* 10 if edge e is already labelled
|
|
* 11 continue with the next edge
|
|
* 12 w <- G.adjacentVertex(t,e)
|
|
* 13 if vertex w is not discovered and not explored
|
|
* 14 label e as tree-edge
|
|
* 15 label w as discovered
|
|
* 16 S.push(w)
|
|
* 17 continue at 5
|
|
* 18 else if vertex w is discovered
|
|
* 19 label e as back-edge
|
|
* 20 else
|
|
* 21 // vertex w is explored
|
|
* 22 label e as forward- or cross-edge
|
|
* 23 label t as explored
|
|
* 24 S.pop()
|
|
*
|
|
* convention:
|
|
* 0x10 - discovered
|
|
* 0x11 - discovered and fall-through edge labelled
|
|
* 0x12 - discovered and fall-through and branch edges labelled
|
|
* 0x20 - explored
|
|
*/
|
|
|
|
enum {
|
|
DISCOVERED = 0x10,
|
|
EXPLORED = 0x20,
|
|
FALLTHROUGH = 1,
|
|
BRANCH = 2,
|
|
};
|
|
|
|
#define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
|
|
|
|
static int *insn_stack; /* stack of insns to process */
|
|
static int cur_stack; /* current stack index */
|
|
static int *insn_state;
|
|
|
|
/* t, w, e - match pseudo-code above:
|
|
* t - index of current instruction
|
|
* w - next instruction
|
|
* e - edge
|
|
*/
|
|
static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
|
|
{
|
|
if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
|
|
return 0;
|
|
|
|
if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
|
|
return 0;
|
|
|
|
if (w < 0 || w >= env->prog->len) {
|
|
verbose("jump out of range from insn %d to %d\n", t, w);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (e == BRANCH)
|
|
/* mark branch target for state pruning */
|
|
env->explored_states[w] = STATE_LIST_MARK;
|
|
|
|
if (insn_state[w] == 0) {
|
|
/* tree-edge */
|
|
insn_state[t] = DISCOVERED | e;
|
|
insn_state[w] = DISCOVERED;
|
|
if (cur_stack >= env->prog->len)
|
|
return -E2BIG;
|
|
insn_stack[cur_stack++] = w;
|
|
return 1;
|
|
} else if ((insn_state[w] & 0xF0) == DISCOVERED) {
|
|
verbose("back-edge from insn %d to %d\n", t, w);
|
|
return -EINVAL;
|
|
} else if (insn_state[w] == EXPLORED) {
|
|
/* forward- or cross-edge */
|
|
insn_state[t] = DISCOVERED | e;
|
|
} else {
|
|
verbose("insn state internal bug\n");
|
|
return -EFAULT;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* non-recursive depth-first-search to detect loops in BPF program
|
|
* loop == back-edge in directed graph
|
|
*/
|
|
static int check_cfg(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_insn *insns = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
int ret = 0;
|
|
int i, t;
|
|
|
|
insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
|
|
if (!insn_state)
|
|
return -ENOMEM;
|
|
|
|
insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
|
|
if (!insn_stack) {
|
|
kfree(insn_state);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
|
|
insn_stack[0] = 0; /* 0 is the first instruction */
|
|
cur_stack = 1;
|
|
|
|
peek_stack:
|
|
if (cur_stack == 0)
|
|
goto check_state;
|
|
t = insn_stack[cur_stack - 1];
|
|
|
|
if (BPF_CLASS(insns[t].code) == BPF_JMP) {
|
|
u8 opcode = BPF_OP(insns[t].code);
|
|
|
|
if (opcode == BPF_EXIT) {
|
|
goto mark_explored;
|
|
} else if (opcode == BPF_CALL) {
|
|
ret = push_insn(t, t + 1, FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
if (t + 1 < insn_cnt)
|
|
env->explored_states[t + 1] = STATE_LIST_MARK;
|
|
} else if (opcode == BPF_JA) {
|
|
if (BPF_SRC(insns[t].code) != BPF_K) {
|
|
ret = -EINVAL;
|
|
goto err_free;
|
|
}
|
|
/* unconditional jump with single edge */
|
|
ret = push_insn(t, t + insns[t].off + 1,
|
|
FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
/* tell verifier to check for equivalent states
|
|
* after every call and jump
|
|
*/
|
|
if (t + 1 < insn_cnt)
|
|
env->explored_states[t + 1] = STATE_LIST_MARK;
|
|
} else {
|
|
/* conditional jump with two edges */
|
|
env->explored_states[t] = STATE_LIST_MARK;
|
|
ret = push_insn(t, t + 1, FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
|
|
ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
}
|
|
} else {
|
|
/* all other non-branch instructions with single
|
|
* fall-through edge
|
|
*/
|
|
ret = push_insn(t, t + 1, FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
}
|
|
|
|
mark_explored:
|
|
insn_state[t] = EXPLORED;
|
|
if (cur_stack-- <= 0) {
|
|
verbose("pop stack internal bug\n");
|
|
ret = -EFAULT;
|
|
goto err_free;
|
|
}
|
|
goto peek_stack;
|
|
|
|
check_state:
|
|
for (i = 0; i < insn_cnt; i++) {
|
|
if (insn_state[i] != EXPLORED) {
|
|
verbose("unreachable insn %d\n", i);
|
|
ret = -EINVAL;
|
|
goto err_free;
|
|
}
|
|
}
|
|
ret = 0; /* cfg looks good */
|
|
|
|
err_free:
|
|
kfree(insn_state);
|
|
kfree(insn_stack);
|
|
return ret;
|
|
}
|
|
|
|
/* the following conditions reduce the number of explored insns
|
|
* from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet
|
|
*/
|
|
static bool compare_ptrs_to_packet(struct bpf_verifier_env *env,
|
|
struct bpf_reg_state *old,
|
|
struct bpf_reg_state *cur)
|
|
{
|
|
if (old->id != cur->id)
|
|
return false;
|
|
|
|
/* old ptr_to_packet is more conservative, since it allows smaller
|
|
* range. Ex:
|
|
* old(off=0,r=10) is equal to cur(off=0,r=20), because
|
|
* old(off=0,r=10) means that with range=10 the verifier proceeded
|
|
* further and found no issues with the program. Now we're in the same
|
|
* spot with cur(off=0,r=20), so we're safe too, since anything further
|
|
* will only be looking at most 10 bytes after this pointer.
|
|
*/
|
|
if (old->off == cur->off && old->range < cur->range)
|
|
return true;
|
|
|
|
/* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0)
|
|
* since both cannot be used for packet access and safe(old)
|
|
* pointer has smaller off that could be used for further
|
|
* 'if (ptr > data_end)' check
|
|
* Ex:
|
|
* old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean
|
|
* that we cannot access the packet.
|
|
* The safe range is:
|
|
* [ptr, ptr + range - off)
|
|
* so whenever off >=range, it means no safe bytes from this pointer.
|
|
* When comparing old->off <= cur->off, it means that older code
|
|
* went with smaller offset and that offset was later
|
|
* used to figure out the safe range after 'if (ptr > data_end)' check
|
|
* Say, 'old' state was explored like:
|
|
* ... R3(off=0, r=0)
|
|
* R4 = R3 + 20
|
|
* ... now R4(off=20,r=0) <-- here
|
|
* if (R4 > data_end)
|
|
* ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access.
|
|
* ... the code further went all the way to bpf_exit.
|
|
* Now the 'cur' state at the mark 'here' has R4(off=30,r=0).
|
|
* old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier
|
|
* goes further, such cur_R4 will give larger safe packet range after
|
|
* 'if (R4 > data_end)' and all further insn were already good with r=20,
|
|
* so they will be good with r=30 and we can prune the search.
|
|
*/
|
|
if (!env->strict_alignment && old->off <= cur->off &&
|
|
old->off >= old->range && cur->off >= cur->range)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/* compare two verifier states
|
|
*
|
|
* all states stored in state_list are known to be valid, since
|
|
* verifier reached 'bpf_exit' instruction through them
|
|
*
|
|
* this function is called when verifier exploring different branches of
|
|
* execution popped from the state stack. If it sees an old state that has
|
|
* more strict register state and more strict stack state then this execution
|
|
* branch doesn't need to be explored further, since verifier already
|
|
* concluded that more strict state leads to valid finish.
|
|
*
|
|
* Therefore two states are equivalent if register state is more conservative
|
|
* and explored stack state is more conservative than the current one.
|
|
* Example:
|
|
* explored current
|
|
* (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
|
|
* (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
|
|
*
|
|
* In other words if current stack state (one being explored) has more
|
|
* valid slots than old one that already passed validation, it means
|
|
* the verifier can stop exploring and conclude that current state is valid too
|
|
*
|
|
* Similarly with registers. If explored state has register type as invalid
|
|
* whereas register type in current state is meaningful, it means that
|
|
* the current state will reach 'bpf_exit' instruction safely
|
|
*/
|
|
static bool states_equal(struct bpf_verifier_env *env,
|
|
struct bpf_verifier_state *old,
|
|
struct bpf_verifier_state *cur)
|
|
{
|
|
bool varlen_map_access = env->varlen_map_value_access;
|
|
struct bpf_reg_state *rold, *rcur;
|
|
int i;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++) {
|
|
rold = &old->regs[i];
|
|
rcur = &cur->regs[i];
|
|
|
|
if (memcmp(rold, rcur, sizeof(*rold)) == 0)
|
|
continue;
|
|
|
|
/* If the ranges were not the same, but everything else was and
|
|
* we didn't do a variable access into a map then we are a-ok.
|
|
*/
|
|
if (!varlen_map_access &&
|
|
memcmp(rold, rcur, offsetofend(struct bpf_reg_state, id)) == 0)
|
|
continue;
|
|
|
|
/* If we didn't map access then again we don't care about the
|
|
* mismatched range values and it's ok if our old type was
|
|
* UNKNOWN and we didn't go to a NOT_INIT'ed reg.
|
|
*/
|
|
if (rold->type == NOT_INIT ||
|
|
(!varlen_map_access && rold->type == UNKNOWN_VALUE &&
|
|
rcur->type != NOT_INIT))
|
|
continue;
|
|
|
|
/* Don't care about the reg->id in this case. */
|
|
if (rold->type == PTR_TO_MAP_VALUE_OR_NULL &&
|
|
rcur->type == PTR_TO_MAP_VALUE_OR_NULL &&
|
|
rold->map_ptr == rcur->map_ptr)
|
|
continue;
|
|
|
|
if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET &&
|
|
compare_ptrs_to_packet(env, rold, rcur))
|
|
continue;
|
|
|
|
return false;
|
|
}
|
|
|
|
for (i = 0; i < MAX_BPF_STACK; i++) {
|
|
if (old->stack_slot_type[i] == STACK_INVALID)
|
|
continue;
|
|
if (old->stack_slot_type[i] != cur->stack_slot_type[i])
|
|
/* Ex: old explored (safe) state has STACK_SPILL in
|
|
* this stack slot, but current has has STACK_MISC ->
|
|
* this verifier states are not equivalent,
|
|
* return false to continue verification of this path
|
|
*/
|
|
return false;
|
|
if (i % BPF_REG_SIZE)
|
|
continue;
|
|
if (old->stack_slot_type[i] != STACK_SPILL)
|
|
continue;
|
|
if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE],
|
|
&cur->spilled_regs[i / BPF_REG_SIZE],
|
|
sizeof(old->spilled_regs[0])))
|
|
/* when explored and current stack slot types are
|
|
* the same, check that stored pointers types
|
|
* are the same as well.
|
|
* Ex: explored safe path could have stored
|
|
* (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8}
|
|
* but current path has stored:
|
|
* (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16}
|
|
* such verifier states are not equivalent.
|
|
* return false to continue verification of this path
|
|
*/
|
|
return false;
|
|
else
|
|
continue;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
|
|
{
|
|
struct bpf_verifier_state_list *new_sl;
|
|
struct bpf_verifier_state_list *sl;
|
|
|
|
sl = env->explored_states[insn_idx];
|
|
if (!sl)
|
|
/* this 'insn_idx' instruction wasn't marked, so we will not
|
|
* be doing state search here
|
|
*/
|
|
return 0;
|
|
|
|
while (sl != STATE_LIST_MARK) {
|
|
if (states_equal(env, &sl->state, &env->cur_state))
|
|
/* reached equivalent register/stack state,
|
|
* prune the search
|
|
*/
|
|
return 1;
|
|
sl = sl->next;
|
|
}
|
|
|
|
/* there were no equivalent states, remember current one.
|
|
* technically the current state is not proven to be safe yet,
|
|
* but it will either reach bpf_exit (which means it's safe) or
|
|
* it will be rejected. Since there are no loops, we won't be
|
|
* seeing this 'insn_idx' instruction again on the way to bpf_exit
|
|
*/
|
|
new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER);
|
|
if (!new_sl)
|
|
return -ENOMEM;
|
|
|
|
/* add new state to the head of linked list */
|
|
memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state));
|
|
new_sl->next = env->explored_states[insn_idx];
|
|
env->explored_states[insn_idx] = new_sl;
|
|
return 0;
|
|
}
|
|
|
|
static int ext_analyzer_insn_hook(struct bpf_verifier_env *env,
|
|
int insn_idx, int prev_insn_idx)
|
|
{
|
|
if (!env->analyzer_ops || !env->analyzer_ops->insn_hook)
|
|
return 0;
|
|
|
|
return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx);
|
|
}
|
|
|
|
static int do_check(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_verifier_state *state = &env->cur_state;
|
|
struct bpf_insn *insns = env->prog->insnsi;
|
|
struct bpf_reg_state *regs = state->regs;
|
|
int insn_cnt = env->prog->len;
|
|
int insn_idx, prev_insn_idx = 0;
|
|
int insn_processed = 0;
|
|
bool do_print_state = false;
|
|
|
|
init_reg_state(regs);
|
|
insn_idx = 0;
|
|
env->varlen_map_value_access = false;
|
|
for (;;) {
|
|
struct bpf_insn *insn;
|
|
u8 class;
|
|
int err;
|
|
|
|
if (insn_idx >= insn_cnt) {
|
|
verbose("invalid insn idx %d insn_cnt %d\n",
|
|
insn_idx, insn_cnt);
|
|
return -EFAULT;
|
|
}
|
|
|
|
insn = &insns[insn_idx];
|
|
class = BPF_CLASS(insn->code);
|
|
|
|
if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
|
|
verbose("BPF program is too large. Processed %d insn\n",
|
|
insn_processed);
|
|
return -E2BIG;
|
|
}
|
|
|
|
err = is_state_visited(env, insn_idx);
|
|
if (err < 0)
|
|
return err;
|
|
if (err == 1) {
|
|
/* found equivalent state, can prune the search */
|
|
if (log_level) {
|
|
if (do_print_state)
|
|
verbose("\nfrom %d to %d: safe\n",
|
|
prev_insn_idx, insn_idx);
|
|
else
|
|
verbose("%d: safe\n", insn_idx);
|
|
}
|
|
goto process_bpf_exit;
|
|
}
|
|
|
|
if (need_resched())
|
|
cond_resched();
|
|
|
|
if (log_level > 1 || (log_level && do_print_state)) {
|
|
if (log_level > 1)
|
|
verbose("%d:", insn_idx);
|
|
else
|
|
verbose("\nfrom %d to %d:",
|
|
prev_insn_idx, insn_idx);
|
|
print_verifier_state(&env->cur_state);
|
|
do_print_state = false;
|
|
}
|
|
|
|
if (log_level) {
|
|
verbose("%d: ", insn_idx);
|
|
print_bpf_insn(env, insn);
|
|
}
|
|
|
|
err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx);
|
|
if (err)
|
|
return err;
|
|
|
|
if (class == BPF_ALU || class == BPF_ALU64) {
|
|
err = check_alu_op(env, insn);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (class == BPF_LDX) {
|
|
enum bpf_reg_type *prev_src_type, src_reg_type;
|
|
|
|
/* check for reserved fields is already done */
|
|
|
|
/* check src operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
|
|
if (err)
|
|
return err;
|
|
|
|
src_reg_type = regs[insn->src_reg].type;
|
|
|
|
/* check that memory (src_reg + off) is readable,
|
|
* the state of dst_reg will be updated by this func
|
|
*/
|
|
err = check_mem_access(env, insn_idx, insn->src_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_READ,
|
|
insn->dst_reg);
|
|
if (err)
|
|
return err;
|
|
|
|
prev_src_type = &env->insn_aux_data[insn_idx].ptr_type;
|
|
|
|
if (*prev_src_type == NOT_INIT) {
|
|
/* saw a valid insn
|
|
* dst_reg = *(u32 *)(src_reg + off)
|
|
* save type to validate intersecting paths
|
|
*/
|
|
*prev_src_type = src_reg_type;
|
|
|
|
} else if (src_reg_type != *prev_src_type &&
|
|
(src_reg_type == PTR_TO_CTX ||
|
|
*prev_src_type == PTR_TO_CTX)) {
|
|
/* ABuser program is trying to use the same insn
|
|
* dst_reg = *(u32*) (src_reg + off)
|
|
* with different pointer types:
|
|
* src_reg == ctx in one branch and
|
|
* src_reg == stack|map in some other branch.
|
|
* Reject it.
|
|
*/
|
|
verbose("same insn cannot be used with different pointers\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
} else if (class == BPF_STX) {
|
|
enum bpf_reg_type *prev_dst_type, dst_reg_type;
|
|
|
|
if (BPF_MODE(insn->code) == BPF_XADD) {
|
|
err = check_xadd(env, insn_idx, insn);
|
|
if (err)
|
|
return err;
|
|
insn_idx++;
|
|
continue;
|
|
}
|
|
|
|
/* check src1 operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
/* check src2 operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
dst_reg_type = regs[insn->dst_reg].type;
|
|
|
|
/* check that memory (dst_reg + off) is writeable */
|
|
err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_WRITE,
|
|
insn->src_reg);
|
|
if (err)
|
|
return err;
|
|
|
|
prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type;
|
|
|
|
if (*prev_dst_type == NOT_INIT) {
|
|
*prev_dst_type = dst_reg_type;
|
|
} else if (dst_reg_type != *prev_dst_type &&
|
|
(dst_reg_type == PTR_TO_CTX ||
|
|
*prev_dst_type == PTR_TO_CTX)) {
|
|
verbose("same insn cannot be used with different pointers\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
} else if (class == BPF_ST) {
|
|
if (BPF_MODE(insn->code) != BPF_MEM ||
|
|
insn->src_reg != BPF_REG_0) {
|
|
verbose("BPF_ST uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
/* check src operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check that memory (dst_reg + off) is writeable */
|
|
err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_WRITE,
|
|
-1);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (class == BPF_JMP) {
|
|
u8 opcode = BPF_OP(insn->code);
|
|
|
|
if (opcode == BPF_CALL) {
|
|
if (BPF_SRC(insn->code) != BPF_K ||
|
|
insn->off != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->dst_reg != BPF_REG_0) {
|
|
verbose("BPF_CALL uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
err = check_call(env, insn->imm, insn_idx);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (opcode == BPF_JA) {
|
|
if (BPF_SRC(insn->code) != BPF_K ||
|
|
insn->imm != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->dst_reg != BPF_REG_0) {
|
|
verbose("BPF_JA uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
insn_idx += insn->off + 1;
|
|
continue;
|
|
|
|
} else if (opcode == BPF_EXIT) {
|
|
if (BPF_SRC(insn->code) != BPF_K ||
|
|
insn->imm != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->dst_reg != BPF_REG_0) {
|
|
verbose("BPF_EXIT uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* eBPF calling convetion is such that R0 is used
|
|
* to return the value from eBPF program.
|
|
* Make sure that it's readable at this time
|
|
* of bpf_exit, which means that program wrote
|
|
* something into it earlier
|
|
*/
|
|
err = check_reg_arg(regs, BPF_REG_0, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (is_pointer_value(env, BPF_REG_0)) {
|
|
verbose("R0 leaks addr as return value\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
process_bpf_exit:
|
|
insn_idx = pop_stack(env, &prev_insn_idx);
|
|
if (insn_idx < 0) {
|
|
break;
|
|
} else {
|
|
do_print_state = true;
|
|
continue;
|
|
}
|
|
} else {
|
|
err = check_cond_jmp_op(env, insn, &insn_idx);
|
|
if (err)
|
|
return err;
|
|
}
|
|
} else if (class == BPF_LD) {
|
|
u8 mode = BPF_MODE(insn->code);
|
|
|
|
if (mode == BPF_ABS || mode == BPF_IND) {
|
|
err = check_ld_abs(env, insn);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (mode == BPF_IMM) {
|
|
err = check_ld_imm(env, insn);
|
|
if (err)
|
|
return err;
|
|
|
|
insn_idx++;
|
|
} else {
|
|
verbose("invalid BPF_LD mode\n");
|
|
return -EINVAL;
|
|
}
|
|
reset_reg_range_values(regs, insn->dst_reg);
|
|
} else {
|
|
verbose("unknown insn class %d\n", class);
|
|
return -EINVAL;
|
|
}
|
|
|
|
insn_idx++;
|
|
}
|
|
|
|
verbose("processed %d insns, stack depth %d\n",
|
|
insn_processed, env->prog->aux->stack_depth);
|
|
return 0;
|
|
}
|
|
|
|
static int check_map_prealloc(struct bpf_map *map)
|
|
{
|
|
return (map->map_type != BPF_MAP_TYPE_HASH &&
|
|
map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
|
|
map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) ||
|
|
!(map->map_flags & BPF_F_NO_PREALLOC);
|
|
}
|
|
|
|
static int check_map_prog_compatibility(struct bpf_map *map,
|
|
struct bpf_prog *prog)
|
|
|
|
{
|
|
/* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use
|
|
* preallocated hash maps, since doing memory allocation
|
|
* in overflow_handler can crash depending on where nmi got
|
|
* triggered.
|
|
*/
|
|
if (prog->type == BPF_PROG_TYPE_PERF_EVENT) {
|
|
if (!check_map_prealloc(map)) {
|
|
verbose("perf_event programs can only use preallocated hash map\n");
|
|
return -EINVAL;
|
|
}
|
|
if (map->inner_map_meta &&
|
|
!check_map_prealloc(map->inner_map_meta)) {
|
|
verbose("perf_event programs can only use preallocated inner hash map\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* look for pseudo eBPF instructions that access map FDs and
|
|
* replace them with actual map pointers
|
|
*/
|
|
static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
int i, j, err;
|
|
|
|
err = bpf_prog_calc_tag(env->prog);
|
|
if (err)
|
|
return err;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++) {
|
|
if (BPF_CLASS(insn->code) == BPF_LDX &&
|
|
(BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
|
|
verbose("BPF_LDX uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (BPF_CLASS(insn->code) == BPF_STX &&
|
|
((BPF_MODE(insn->code) != BPF_MEM &&
|
|
BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
|
|
verbose("BPF_STX uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
|
|
struct bpf_map *map;
|
|
struct fd f;
|
|
|
|
if (i == insn_cnt - 1 || insn[1].code != 0 ||
|
|
insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
|
|
insn[1].off != 0) {
|
|
verbose("invalid bpf_ld_imm64 insn\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn->src_reg == 0)
|
|
/* valid generic load 64-bit imm */
|
|
goto next_insn;
|
|
|
|
if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
|
|
verbose("unrecognized bpf_ld_imm64 insn\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
f = fdget(insn->imm);
|
|
map = __bpf_map_get(f);
|
|
if (IS_ERR(map)) {
|
|
verbose("fd %d is not pointing to valid bpf_map\n",
|
|
insn->imm);
|
|
return PTR_ERR(map);
|
|
}
|
|
|
|
err = check_map_prog_compatibility(map, env->prog);
|
|
if (err) {
|
|
fdput(f);
|
|
return err;
|
|
}
|
|
|
|
/* store map pointer inside BPF_LD_IMM64 instruction */
|
|
insn[0].imm = (u32) (unsigned long) map;
|
|
insn[1].imm = ((u64) (unsigned long) map) >> 32;
|
|
|
|
/* check whether we recorded this map already */
|
|
for (j = 0; j < env->used_map_cnt; j++)
|
|
if (env->used_maps[j] == map) {
|
|
fdput(f);
|
|
goto next_insn;
|
|
}
|
|
|
|
if (env->used_map_cnt >= MAX_USED_MAPS) {
|
|
fdput(f);
|
|
return -E2BIG;
|
|
}
|
|
|
|
/* hold the map. If the program is rejected by verifier,
|
|
* the map will be released by release_maps() or it
|
|
* will be used by the valid program until it's unloaded
|
|
* and all maps are released in free_bpf_prog_info()
|
|
*/
|
|
map = bpf_map_inc(map, false);
|
|
if (IS_ERR(map)) {
|
|
fdput(f);
|
|
return PTR_ERR(map);
|
|
}
|
|
env->used_maps[env->used_map_cnt++] = map;
|
|
|
|
fdput(f);
|
|
next_insn:
|
|
insn++;
|
|
i++;
|
|
}
|
|
}
|
|
|
|
/* now all pseudo BPF_LD_IMM64 instructions load valid
|
|
* 'struct bpf_map *' into a register instead of user map_fd.
|
|
* These pointers will be used later by verifier to validate map access.
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
/* drop refcnt of maps used by the rejected program */
|
|
static void release_maps(struct bpf_verifier_env *env)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < env->used_map_cnt; i++)
|
|
bpf_map_put(env->used_maps[i]);
|
|
}
|
|
|
|
/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
|
|
static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
int i;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++)
|
|
if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
|
|
insn->src_reg = 0;
|
|
}
|
|
|
|
/* single env->prog->insni[off] instruction was replaced with the range
|
|
* insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
|
|
* [0, off) and [off, end) to new locations, so the patched range stays zero
|
|
*/
|
|
static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
|
|
u32 off, u32 cnt)
|
|
{
|
|
struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
|
|
|
|
if (cnt == 1)
|
|
return 0;
|
|
new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len);
|
|
if (!new_data)
|
|
return -ENOMEM;
|
|
memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
|
|
memcpy(new_data + off + cnt - 1, old_data + off,
|
|
sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
|
|
env->insn_aux_data = new_data;
|
|
vfree(old_data);
|
|
return 0;
|
|
}
|
|
|
|
static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
|
|
const struct bpf_insn *patch, u32 len)
|
|
{
|
|
struct bpf_prog *new_prog;
|
|
|
|
new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
|
|
if (!new_prog)
|
|
return NULL;
|
|
if (adjust_insn_aux_data(env, new_prog->len, off, len))
|
|
return NULL;
|
|
return new_prog;
|
|
}
|
|
|
|
/* convert load instructions that access fields of 'struct __sk_buff'
|
|
* into sequence of instructions that access fields of 'struct sk_buff'
|
|
*/
|
|
static int convert_ctx_accesses(struct bpf_verifier_env *env)
|
|
{
|
|
const struct bpf_verifier_ops *ops = env->prog->aux->ops;
|
|
int i, cnt, size, ctx_field_size, delta = 0;
|
|
const int insn_cnt = env->prog->len;
|
|
struct bpf_insn insn_buf[16], *insn;
|
|
struct bpf_prog *new_prog;
|
|
enum bpf_access_type type;
|
|
bool is_narrower_load;
|
|
u32 target_size;
|
|
|
|
if (ops->gen_prologue) {
|
|
cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
|
|
env->prog);
|
|
if (cnt >= ARRAY_SIZE(insn_buf)) {
|
|
verbose("bpf verifier is misconfigured\n");
|
|
return -EINVAL;
|
|
} else if (cnt) {
|
|
new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
env->prog = new_prog;
|
|
delta += cnt - 1;
|
|
}
|
|
}
|
|
|
|
if (!ops->convert_ctx_access)
|
|
return 0;
|
|
|
|
insn = env->prog->insnsi + delta;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++) {
|
|
if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
|
|
insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
|
|
insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
|
|
insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
|
|
type = BPF_READ;
|
|
else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
|
|
insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
|
|
insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
|
|
insn->code == (BPF_STX | BPF_MEM | BPF_DW))
|
|
type = BPF_WRITE;
|
|
else
|
|
continue;
|
|
|
|
if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX)
|
|
continue;
|
|
|
|
ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
|
|
size = BPF_LDST_BYTES(insn);
|
|
|
|
/* If the read access is a narrower load of the field,
|
|
* convert to a 4/8-byte load, to minimum program type specific
|
|
* convert_ctx_access changes. If conversion is successful,
|
|
* we will apply proper mask to the result.
|
|
*/
|
|
is_narrower_load = size < ctx_field_size;
|
|
if (is_narrower_load) {
|
|
u32 off = insn->off;
|
|
u8 size_code;
|
|
|
|
if (type == BPF_WRITE) {
|
|
verbose("bpf verifier narrow ctx access misconfigured\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
size_code = BPF_H;
|
|
if (ctx_field_size == 4)
|
|
size_code = BPF_W;
|
|
else if (ctx_field_size == 8)
|
|
size_code = BPF_DW;
|
|
|
|
insn->off = off & ~(ctx_field_size - 1);
|
|
insn->code = BPF_LDX | BPF_MEM | size_code;
|
|
}
|
|
|
|
target_size = 0;
|
|
cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog,
|
|
&target_size);
|
|
if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
|
|
(ctx_field_size && !target_size)) {
|
|
verbose("bpf verifier is misconfigured\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (is_narrower_load && size < target_size) {
|
|
if (ctx_field_size <= 4)
|
|
insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
|
|
(1 << size * 8) - 1);
|
|
else
|
|
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg,
|
|
(1 << size * 8) - 1);
|
|
}
|
|
|
|
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
delta += cnt - 1;
|
|
|
|
/* keep walking new program and skip insns we just inserted */
|
|
env->prog = new_prog;
|
|
insn = new_prog->insnsi + i + delta;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* fixup insn->imm field of bpf_call instructions
|
|
* and inline eligible helpers as explicit sequence of BPF instructions
|
|
*
|
|
* this function is called after eBPF program passed verification
|
|
*/
|
|
static int fixup_bpf_calls(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_prog *prog = env->prog;
|
|
struct bpf_insn *insn = prog->insnsi;
|
|
const struct bpf_func_proto *fn;
|
|
const int insn_cnt = prog->len;
|
|
struct bpf_insn insn_buf[16];
|
|
struct bpf_prog *new_prog;
|
|
struct bpf_map *map_ptr;
|
|
int i, cnt, delta = 0;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++) {
|
|
if (insn->code != (BPF_JMP | BPF_CALL))
|
|
continue;
|
|
|
|
if (insn->imm == BPF_FUNC_get_route_realm)
|
|
prog->dst_needed = 1;
|
|
if (insn->imm == BPF_FUNC_get_prandom_u32)
|
|
bpf_user_rnd_init_once();
|
|
if (insn->imm == BPF_FUNC_tail_call) {
|
|
/* If we tail call into other programs, we
|
|
* cannot make any assumptions since they can
|
|
* be replaced dynamically during runtime in
|
|
* the program array.
|
|
*/
|
|
prog->cb_access = 1;
|
|
env->prog->aux->stack_depth = MAX_BPF_STACK;
|
|
|
|
/* mark bpf_tail_call as different opcode to avoid
|
|
* conditional branch in the interpeter for every normal
|
|
* call and to prevent accidental JITing by JIT compiler
|
|
* that doesn't support bpf_tail_call yet
|
|
*/
|
|
insn->imm = 0;
|
|
insn->code = BPF_JMP | BPF_TAIL_CALL;
|
|
continue;
|
|
}
|
|
|
|
if (ebpf_jit_enabled() && insn->imm == BPF_FUNC_map_lookup_elem) {
|
|
map_ptr = env->insn_aux_data[i + delta].map_ptr;
|
|
if (map_ptr == BPF_MAP_PTR_POISON ||
|
|
!map_ptr->ops->map_gen_lookup)
|
|
goto patch_call_imm;
|
|
|
|
cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf);
|
|
if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
|
|
verbose("bpf verifier is misconfigured\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf,
|
|
cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
delta += cnt - 1;
|
|
|
|
/* keep walking new program and skip insns we just inserted */
|
|
env->prog = prog = new_prog;
|
|
insn = new_prog->insnsi + i + delta;
|
|
continue;
|
|
}
|
|
|
|
patch_call_imm:
|
|
fn = prog->aux->ops->get_func_proto(insn->imm);
|
|
/* all functions that have prototype and verifier allowed
|
|
* programs to call them, must be real in-kernel functions
|
|
*/
|
|
if (!fn->func) {
|
|
verbose("kernel subsystem misconfigured func %s#%d\n",
|
|
func_id_name(insn->imm), insn->imm);
|
|
return -EFAULT;
|
|
}
|
|
insn->imm = fn->func - __bpf_call_base;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void free_states(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_verifier_state_list *sl, *sln;
|
|
int i;
|
|
|
|
if (!env->explored_states)
|
|
return;
|
|
|
|
for (i = 0; i < env->prog->len; i++) {
|
|
sl = env->explored_states[i];
|
|
|
|
if (sl)
|
|
while (sl != STATE_LIST_MARK) {
|
|
sln = sl->next;
|
|
kfree(sl);
|
|
sl = sln;
|
|
}
|
|
}
|
|
|
|
kfree(env->explored_states);
|
|
}
|
|
|
|
int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
|
|
{
|
|
char __user *log_ubuf = NULL;
|
|
struct bpf_verifier_env *env;
|
|
int ret = -EINVAL;
|
|
|
|
/* 'struct bpf_verifier_env' can be global, but since it's not small,
|
|
* allocate/free it every time bpf_check() is called
|
|
*/
|
|
env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
|
|
if (!env)
|
|
return -ENOMEM;
|
|
|
|
env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
|
|
(*prog)->len);
|
|
ret = -ENOMEM;
|
|
if (!env->insn_aux_data)
|
|
goto err_free_env;
|
|
env->prog = *prog;
|
|
|
|
/* grab the mutex to protect few globals used by verifier */
|
|
mutex_lock(&bpf_verifier_lock);
|
|
|
|
if (attr->log_level || attr->log_buf || attr->log_size) {
|
|
/* user requested verbose verifier output
|
|
* and supplied buffer to store the verification trace
|
|
*/
|
|
log_level = attr->log_level;
|
|
log_ubuf = (char __user *) (unsigned long) attr->log_buf;
|
|
log_size = attr->log_size;
|
|
log_len = 0;
|
|
|
|
ret = -EINVAL;
|
|
/* log_* values have to be sane */
|
|
if (log_size < 128 || log_size > UINT_MAX >> 8 ||
|
|
log_level == 0 || log_ubuf == NULL)
|
|
goto err_unlock;
|
|
|
|
ret = -ENOMEM;
|
|
log_buf = vmalloc(log_size);
|
|
if (!log_buf)
|
|
goto err_unlock;
|
|
} else {
|
|
log_level = 0;
|
|
}
|
|
|
|
env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
|
|
if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
|
|
env->strict_alignment = true;
|
|
|
|
ret = replace_map_fd_with_map_ptr(env);
|
|
if (ret < 0)
|
|
goto skip_full_check;
|
|
|
|
env->explored_states = kcalloc(env->prog->len,
|
|
sizeof(struct bpf_verifier_state_list *),
|
|
GFP_USER);
|
|
ret = -ENOMEM;
|
|
if (!env->explored_states)
|
|
goto skip_full_check;
|
|
|
|
ret = check_cfg(env);
|
|
if (ret < 0)
|
|
goto skip_full_check;
|
|
|
|
env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
|
|
|
|
ret = do_check(env);
|
|
|
|
skip_full_check:
|
|
while (pop_stack(env, NULL) >= 0);
|
|
free_states(env);
|
|
|
|
if (ret == 0)
|
|
/* program is valid, convert *(u32*)(ctx + off) accesses */
|
|
ret = convert_ctx_accesses(env);
|
|
|
|
if (ret == 0)
|
|
ret = fixup_bpf_calls(env);
|
|
|
|
if (log_level && log_len >= log_size - 1) {
|
|
BUG_ON(log_len >= log_size);
|
|
/* verifier log exceeded user supplied buffer */
|
|
ret = -ENOSPC;
|
|
/* fall through to return what was recorded */
|
|
}
|
|
|
|
/* copy verifier log back to user space including trailing zero */
|
|
if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) {
|
|
ret = -EFAULT;
|
|
goto free_log_buf;
|
|
}
|
|
|
|
if (ret == 0 && env->used_map_cnt) {
|
|
/* if program passed verifier, update used_maps in bpf_prog_info */
|
|
env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
|
|
sizeof(env->used_maps[0]),
|
|
GFP_KERNEL);
|
|
|
|
if (!env->prog->aux->used_maps) {
|
|
ret = -ENOMEM;
|
|
goto free_log_buf;
|
|
}
|
|
|
|
memcpy(env->prog->aux->used_maps, env->used_maps,
|
|
sizeof(env->used_maps[0]) * env->used_map_cnt);
|
|
env->prog->aux->used_map_cnt = env->used_map_cnt;
|
|
|
|
/* program is valid. Convert pseudo bpf_ld_imm64 into generic
|
|
* bpf_ld_imm64 instructions
|
|
*/
|
|
convert_pseudo_ld_imm64(env);
|
|
}
|
|
|
|
free_log_buf:
|
|
if (log_level)
|
|
vfree(log_buf);
|
|
if (!env->prog->aux->used_maps)
|
|
/* if we didn't copy map pointers into bpf_prog_info, release
|
|
* them now. Otherwise free_bpf_prog_info() will release them.
|
|
*/
|
|
release_maps(env);
|
|
*prog = env->prog;
|
|
err_unlock:
|
|
mutex_unlock(&bpf_verifier_lock);
|
|
vfree(env->insn_aux_data);
|
|
err_free_env:
|
|
kfree(env);
|
|
return ret;
|
|
}
|
|
|
|
int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
|
|
void *priv)
|
|
{
|
|
struct bpf_verifier_env *env;
|
|
int ret;
|
|
|
|
env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
|
|
if (!env)
|
|
return -ENOMEM;
|
|
|
|
env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
|
|
prog->len);
|
|
ret = -ENOMEM;
|
|
if (!env->insn_aux_data)
|
|
goto err_free_env;
|
|
env->prog = prog;
|
|
env->analyzer_ops = ops;
|
|
env->analyzer_priv = priv;
|
|
|
|
/* grab the mutex to protect few globals used by verifier */
|
|
mutex_lock(&bpf_verifier_lock);
|
|
|
|
log_level = 0;
|
|
|
|
env->strict_alignment = false;
|
|
if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
|
|
env->strict_alignment = true;
|
|
|
|
env->explored_states = kcalloc(env->prog->len,
|
|
sizeof(struct bpf_verifier_state_list *),
|
|
GFP_KERNEL);
|
|
ret = -ENOMEM;
|
|
if (!env->explored_states)
|
|
goto skip_full_check;
|
|
|
|
ret = check_cfg(env);
|
|
if (ret < 0)
|
|
goto skip_full_check;
|
|
|
|
env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
|
|
|
|
ret = do_check(env);
|
|
|
|
skip_full_check:
|
|
while (pop_stack(env, NULL) >= 0);
|
|
free_states(env);
|
|
|
|
mutex_unlock(&bpf_verifier_lock);
|
|
vfree(env->insn_aux_data);
|
|
err_free_env:
|
|
kfree(env);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(bpf_analyzer);
|