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bpf: refactor fixup_bpf_calls() 

reduce indent and make it iterate over instructions similar to
convert_ctx_accesses(). Also convert hard BUG_ON into soft verifier error.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2017-03-15 18:26:40 -07:00 committed by David S. Miller
parent e245c5c6a5
commit 79741b3bde
1 changed files with 37 additions and 43 deletions
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80
kernel/bpf/verifier.c
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@ -3233,59 +3233,53 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
return 0; return 0;
} }
/* fixup insn->imm field of bpf_call instructions: /* fixup insn->imm field of bpf_call instructions
* if (insn->imm == BPF_FUNC_map_lookup_elem)
* insn->imm = bpf_map_lookup_elem - __bpf_call_base;
* else if (insn->imm == BPF_FUNC_map_update_elem)
* insn->imm = bpf_map_update_elem - __bpf_call_base;
* else ...
* *
* this function is called after eBPF program passed verification * this function is called after eBPF program passed verification
*/ */
static void fixup_bpf_calls(struct bpf_prog *prog) 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 struct bpf_func_proto *fn;
const int insn_cnt = prog->len;
int i; int i;
for (i = 0; i < prog->len; i++) { for (i = 0; i < insn_cnt; i++, insn++) {
struct bpf_insn *insn = &prog->insnsi[i]; if (insn->code != (BPF_JMP | BPF_CALL))
continue;
if (insn->code == (BPF_JMP | BPF_CALL)) { if (insn->imm == BPF_FUNC_get_route_realm)
/* we reach here when program has bpf_call instructions prog->dst_needed = 1;
* and it passed bpf_check(), means that if (insn->imm == BPF_FUNC_get_prandom_u32)
* ops->get_func_proto must have been supplied, check it bpf_user_rnd_init_once();
if (insn->imm == BPF_FUNC_xdp_adjust_head)
prog->xdp_adjust_head = 1;
if (insn->imm == BPF_FUNC_tail_call) {
/* 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
*/ */
BUG_ON(!prog->aux->ops->get_func_proto); insn->imm = 0;
insn->code |= BPF_X;
if (insn->imm == BPF_FUNC_get_route_realm) continue;
prog->dst_needed = 1;
if (insn->imm == BPF_FUNC_get_prandom_u32)
bpf_user_rnd_init_once();
if (insn->imm == BPF_FUNC_xdp_adjust_head)
prog->xdp_adjust_head = 1;
if (insn->imm == BPF_FUNC_tail_call) {
/* mark bpf_tail_call as different opcode
* to avoid conditional branch in
* 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_X;
continue;
}
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
*/
BUG_ON(!fn->func);
insn->imm = fn->func - __bpf_call_base;
} }
}
}
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) static void free_states(struct bpf_verifier_env *env)
{ {
@ -3383,7 +3377,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
ret = convert_ctx_accesses(env); ret = convert_ctx_accesses(env);
if (ret == 0) if (ret == 0)
fixup_bpf_calls(env->prog); ret = fixup_bpf_calls(env);
if (log_level && log_len >= log_size - 1) { if (log_level && log_len >= log_size - 1) {
BUG_ON(log_len >= log_size); BUG_ON(log_len >= log_size);