Drop __rcu annotations and rcu read sections from bpf_prog_array
helper functions. They are not needed since all existing callers
call those helpers from the rcu update side while holding a mutex.
This guarantees that use-after-free could not happen.
In the next patches I'll fix the callers with missing
rcu_dereference_protected to make sparse/lockdep happy, the proper
way to use these helpers is:
struct bpf_prog_array __rcu *progs = ...;
struct bpf_prog_array *p;
mutex_lock(&mtx);
p = rcu_dereference_protected(progs, lockdep_is_held(&mtx));
bpf_prog_array_length(p);
bpf_prog_array_copy_to_user(p, ...);
bpf_prog_array_delete_safe(p, ...);
bpf_prog_array_copy_info(p, ...);
bpf_prog_array_copy(p, ...);
bpf_prog_array_free(p);
mutex_unlock(&mtx);
No functional changes! rcu_dereference_protected with lockdep_is_held
should catch any cases where we update prog array without a mutex
(I've looked at existing call sites and I think we hold a mutex
everywhere).
Motivation is to fix sparse warnings:
kernel/bpf/core.c:1803:9: warning: incorrect type in argument 1 (different address spaces)
kernel/bpf/core.c:1803:9: expected struct callback_head *head
kernel/bpf/core.c:1803:9: got struct callback_head [noderef] <asn:4> *
kernel/bpf/core.c:1877:44: warning: incorrect type in initializer (different address spaces)
kernel/bpf/core.c:1877:44: expected struct bpf_prog_array_item *item
kernel/bpf/core.c:1877:44: got struct bpf_prog_array_item [noderef] <asn:4> *
kernel/bpf/core.c:1901:26: warning: incorrect type in assignment (different address spaces)
kernel/bpf/core.c:1901:26: expected struct bpf_prog_array_item *existing
kernel/bpf/core.c:1901:26: got struct bpf_prog_array_item [noderef] <asn:4> *
kernel/bpf/core.c:1935:26: warning: incorrect type in assignment (different address spaces)
kernel/bpf/core.c:1935:26: expected struct bpf_prog_array_item *[assigned] existing
kernel/bpf/core.c:1935:26: got struct bpf_prog_array_item [noderef] <asn:4> *
v2:
* remove comment about potential race; that can't happen
because all callers are in rcu-update section
Cc: Roman Gushchin <guro@fb.com>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
After previous patches, verifier will mark a insn if it really needs zero
extension on dst_reg.
It is then for back-ends to decide how to use such information to eliminate
unnecessary zero extension code-gen during JIT compilation.
One approach is verifier insert explicit zero extension for those insns
that need zero extension in a generic way, JIT back-ends then do not
generate zero extension for sub-register write at default.
However, only those back-ends which do not have hardware zero extension
want this optimization. Back-ends like x86_64 and AArch64 have hardware
zero extension support that the insertion should be disabled.
This patch introduces new target hook "bpf_jit_needs_zext" which returns
false at default, meaning verifier zero extension insertion is disabled at
default. A back-end could override this hook to return true if it doesn't
have hardware support and want verifier insert zero extension explicitly.
Offload targets do not use this native target hook, instead, they could
get the optimization results using bpf_prog_offload_ops.finalize.
NOTE: arches could have diversified features, it is possible for one arch
to have hardware zero extension support for some sub-register write insns
but not for all. For example, PowerPC, SPARC have zero extended loads, but
not for alu32. So when verifier zero extension insertion enabled, these JIT
back-ends need to peephole insns to remove those zero extension inserted
for insn that actually has hardware zero extension support. The peephole
could be as simple as looking the next insn, if it is a special zero
extension insn then it is safe to eliminate it if the current insn has
hardware zero extension support.
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Pull networking updates from David Miller:
"Highlights:
1) Support AES128-CCM ciphers in kTLS, from Vakul Garg.
2) Add fib_sync_mem to control the amount of dirty memory we allow to
queue up between synchronize RCU calls, from David Ahern.
3) Make flow classifier more lockless, from Vlad Buslov.
4) Add PHY downshift support to aquantia driver, from Heiner
Kallweit.
5) Add SKB cache for TCP rx and tx, from Eric Dumazet. This reduces
contention on SLAB spinlocks in heavy RPC workloads.
6) Partial GSO offload support in XFRM, from Boris Pismenny.
7) Add fast link down support to ethtool, from Heiner Kallweit.
8) Use siphash for IP ID generator, from Eric Dumazet.
9) Pull nexthops even further out from ipv4/ipv6 routes and FIB
entries, from David Ahern.
10) Move skb->xmit_more into a per-cpu variable, from Florian
Westphal.
11) Improve eBPF verifier speed and increase maximum program size,
from Alexei Starovoitov.
12) Eliminate per-bucket spinlocks in rhashtable, and instead use bit
spinlocks. From Neil Brown.
13) Allow tunneling with GUE encap in ipvs, from Jacky Hu.
14) Improve link partner cap detection in generic PHY code, from
Heiner Kallweit.
15) Add layer 2 encap support to bpf_skb_adjust_room(), from Alan
Maguire.
16) Remove SKB list implementation assumptions in SCTP, your's truly.
17) Various cleanups, optimizations, and simplifications in r8169
driver. From Heiner Kallweit.
18) Add memory accounting on TX and RX path of SCTP, from Xin Long.
19) Switch PHY drivers over to use dynamic featue detection, from
Heiner Kallweit.
20) Support flow steering without masking in dpaa2-eth, from Ioana
Ciocoi.
21) Implement ndo_get_devlink_port in netdevsim driver, from Jiri
Pirko.
22) Increase the strict parsing of current and future netlink
attributes, also export such policies to userspace. From Johannes
Berg.
23) Allow DSA tag drivers to be modular, from Andrew Lunn.
24) Remove legacy DSA probing support, also from Andrew Lunn.
25) Allow ll_temac driver to be used on non-x86 platforms, from Esben
Haabendal.
26) Add a generic tracepoint for TX queue timeouts to ease debugging,
from Cong Wang.
27) More indirect call optimizations, from Paolo Abeni"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1763 commits)
cxgb4: Fix error path in cxgb4_init_module
net: phy: improve pause mode reporting in phy_print_status
dt-bindings: net: Fix a typo in the phy-mode list for ethernet bindings
net: macb: Change interrupt and napi enable order in open
net: ll_temac: Improve error message on error IRQ
net/sched: remove block pointer from common offload structure
net: ethernet: support of_get_mac_address new ERR_PTR error
net: usb: smsc: fix warning reported by kbuild test robot
staging: octeon-ethernet: Fix of_get_mac_address ERR_PTR check
net: dsa: support of_get_mac_address new ERR_PTR error
net: dsa: sja1105: Fix status initialization in sja1105_get_ethtool_stats
vrf: sit mtu should not be updated when vrf netdev is the link
net: dsa: Fix error cleanup path in dsa_init_module
l2tp: Fix possible NULL pointer dereference
taprio: add null check on sched_nest to avoid potential null pointer dereference
net: mvpp2: cls: fix less than zero check on a u32 variable
net_sched: sch_fq: handle non connected flows
net_sched: sch_fq: do not assume EDT packets are ordered
net: hns3: use devm_kcalloc when allocating desc_cb
net: hns3: some cleanup for struct hns3_enet_ring
...
Use new flag VM_FLUSH_RESET_PERMS for handling freeing of special
permissioned memory in vmalloc and remove places where memory was set RW
before freeing which is no longer needed. Don't track if the memory is RO
anymore because it is now tracked in vmalloc.
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <akpm@linux-foundation.org>
Cc: <ard.biesheuvel@linaro.org>
Cc: <deneen.t.dock@intel.com>
Cc: <kernel-hardening@lists.openwall.com>
Cc: <kristen@linux.intel.com>
Cc: <linux_dti@icloud.com>
Cc: <will.deacon@arm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-19-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This generic extension to BPF maps allows for directly loading
an address residing inside a BPF map value as a single BPF
ldimm64 instruction!
The idea is similar to what BPF_PSEUDO_MAP_FD does today, which
is a special src_reg flag for ldimm64 instruction that indicates
that inside the first part of the double insns's imm field is a
file descriptor which the verifier then replaces as a full 64bit
address of the map into both imm parts. For the newly added
BPF_PSEUDO_MAP_VALUE src_reg flag, the idea is the following:
the first part of the double insns's imm field is again a file
descriptor corresponding to the map, and the second part of the
imm field is an offset into the value. The verifier will then
replace both imm parts with an address that points into the BPF
map value at the given value offset for maps that support this
operation. Currently supported is array map with single entry.
It is possible to support more than just single map element by
reusing both 16bit off fields of the insns as a map index, so
full array map lookup could be expressed that way. It hasn't
been implemented here due to lack of concrete use case, but
could easily be done so in future in a compatible way, since
both off fields right now have to be 0 and would correctly
denote a map index 0.
The BPF_PSEUDO_MAP_VALUE is a distinct flag as otherwise with
BPF_PSEUDO_MAP_FD we could not differ offset 0 between load of
map pointer versus load of map's value at offset 0, and changing
BPF_PSEUDO_MAP_FD's encoding into off by one to differ between
regular map pointer and map value pointer would add unnecessary
complexity and increases barrier for debugability thus less
suitable. Using the second part of the imm field as an offset
into the value does /not/ come with limitations since maximum
possible value size is in u32 universe anyway.
This optimization allows for efficiently retrieving an address
to a map value memory area without having to issue a helper call
which needs to prepare registers according to calling convention,
etc, without needing the extra NULL test, and without having to
add the offset in an additional instruction to the value base
pointer. The verifier then treats the destination register as
PTR_TO_MAP_VALUE with constant reg->off from the user passed
offset from the second imm field, and guarantees that this is
within bounds of the map value. Any subsequent operations are
normally treated as typical map value handling without anything
extra needed from verification side.
The two map operations for direct value access have been added to
array map for now. In future other types could be supported as
well depending on the use case. The main use case for this commit
is to allow for BPF loader support for global variables that
reside in .data/.rodata/.bss sections such that we can directly
load the address of them with minimal additional infrastructure
required. Loader support has been added in subsequent commits for
libbpf library.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Larger programs may trigger 16-bit jump offset overflow check
during instruction patching. Make this error verbose otherwise
users cannot decipher error code without printks in the verifier.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Pull perf updates from Ingo Molnar:
"Lots of tooling updates - too many to list, here's a few highlights:
- Various subcommand updates to 'perf trace', 'perf report', 'perf
record', 'perf annotate', 'perf script', 'perf test', etc.
- CPU and NUMA topology and affinity handling improvements,
- HW tracing and HW support updates:
- Intel PT updates
- ARM CoreSight updates
- vendor HW event updates
- BPF updates
- Tons of infrastructure updates, both on the build system and the
library support side
- Documentation updates.
- ... and lots of other changes, see the changelog for details.
Kernel side updates:
- Tighten up kprobes blacklist handling, reduce the number of places
where developers can install a kprobe and hang/crash the system.
- Fix/enhance vma address filter handling.
- Various PMU driver updates, small fixes and additions.
- refcount_t conversions
- BPF updates
- error code propagation enhancements
- misc other changes"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (238 commits)
perf script python: Add Python3 support to syscall-counts-by-pid.py
perf script python: Add Python3 support to syscall-counts.py
perf script python: Add Python3 support to stat-cpi.py
perf script python: Add Python3 support to stackcollapse.py
perf script python: Add Python3 support to sctop.py
perf script python: Add Python3 support to powerpc-hcalls.py
perf script python: Add Python3 support to net_dropmonitor.py
perf script python: Add Python3 support to mem-phys-addr.py
perf script python: Add Python3 support to failed-syscalls-by-pid.py
perf script python: Add Python3 support to netdev-times.py
perf tools: Add perf_exe() helper to find perf binary
perf script: Handle missing fields with -F +..
perf data: Add perf_data__open_dir_data function
perf data: Add perf_data__(create_dir|close_dir) functions
perf data: Fail check_backup in case of error
perf data: Make check_backup work over directories
perf tools: Add rm_rf_perf_data function
perf tools: Add pattern name checking to rm_rf
perf tools: Add depth checking to rm_rf
perf data: Add global path holder
...
We need to iterate through all possible cpus.
Fixes: 492ecee892 ("bpf: enable program stats")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
JITed BPF programs are indistinguishable from kernel functions, but unlike
kernel code BPF code can be changed often.
Typical approach of "perf record" + "perf report" profiling and tuning of
kernel code works just as well for BPF programs, but kernel code doesn't
need to be monitored whereas BPF programs do.
Users load and run large amount of BPF programs.
These BPF stats allow tools monitor the usage of BPF on the server.
The monitoring tools will turn sysctl kernel.bpf_stats_enabled
on and off for few seconds to sample average cost of the programs.
Aggregated data over hours and days will provide an insight into cost of BPF
and alarms can trigger in case given program suddenly gets more expensive.
The cost of two sched_clock() per program invocation adds ~20 nsec.
Fast BPF progs (like selftests/bpf/progs/test_pkt_access.c) will slow down
from ~10 nsec to ~30 nsec.
static_key minimizes the cost of the stats collection.
There is no measurable difference before/after this patch
with kernel.bpf_stats_enabled=0
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Introduce 'struct bpf_spin_lock' and bpf_spin_lock/unlock() helpers to let
bpf program serialize access to other variables.
Example:
struct hash_elem {
int cnt;
struct bpf_spin_lock lock;
};
struct hash_elem * val = bpf_map_lookup_elem(&hash_map, &key);
if (val) {
bpf_spin_lock(&val->lock);
val->cnt++;
bpf_spin_unlock(&val->lock);
}
Restrictions and safety checks:
- bpf_spin_lock is only allowed inside HASH and ARRAY maps.
- BTF description of the map is mandatory for safety analysis.
- bpf program can take one bpf_spin_lock at a time, since two or more can
cause dead locks.
- only one 'struct bpf_spin_lock' is allowed per map element.
It drastically simplifies implementation yet allows bpf program to use
any number of bpf_spin_locks.
- when bpf_spin_lock is taken the calls (either bpf2bpf or helpers) are not allowed.
- bpf program must bpf_spin_unlock() before return.
- bpf program can access 'struct bpf_spin_lock' only via
bpf_spin_lock()/bpf_spin_unlock() helpers.
- load/store into 'struct bpf_spin_lock lock;' field is not allowed.
- to use bpf_spin_lock() helper the BTF description of map value must be
a struct and have 'struct bpf_spin_lock anyname;' field at the top level.
Nested lock inside another struct is not allowed.
- syscall map_lookup doesn't copy bpf_spin_lock field to user space.
- syscall map_update and program map_update do not update bpf_spin_lock field.
- bpf_spin_lock cannot be on the stack or inside networking packet.
bpf_spin_lock can only be inside HASH or ARRAY map value.
- bpf_spin_lock is available to root only and to all program types.
- bpf_spin_lock is not allowed in inner maps of map-in-map.
- ld_abs is not allowed inside spin_lock-ed region.
- tracing progs and socket filter progs cannot use bpf_spin_lock due to
insufficient preemption checks
Implementation details:
- cgroup-bpf class of programs can nest with xdp/tc programs.
Hence bpf_spin_lock is equivalent to spin_lock_irqsave.
Other solutions to avoid nested bpf_spin_lock are possible.
Like making sure that all networking progs run with softirq disabled.
spin_lock_irqsave is the simplest and doesn't add overhead to the
programs that don't use it.
- arch_spinlock_t is used when its implemented as queued_spin_lock
- archs can force their own arch_spinlock_t
- on architectures where queued_spin_lock is not available and
sizeof(arch_spinlock_t) != sizeof(__u32) trivial lock is used.
- presence of bpf_spin_lock inside map value could have been indicated via
extra flag during map_create, but specifying it via BTF is cleaner.
It provides introspection for map key/value and reduces user mistakes.
Next steps:
- allow bpf_spin_lock in other map types (like cgroup local storage)
- introduce BPF_F_LOCK flag for bpf_map_update() syscall and helper
to request kernel to grab bpf_spin_lock before rewriting the value.
That will serialize access to map elements.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Over the years, the function signature has changed, but the
kerneldoc block hasn't.
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch adds JIT blinds support for JMP32.
Like BPF_JMP_REG/IMM, JMP32 version are needed for building raw bpf insn.
They are added to both include/linux/filter.h and
tools/include/linux/filter.h.
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch implements interpreting new JMP32 instructions.
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch teach verifier about the new BPF_JMP32 instruction class.
Verifier need to treat it similar as the existing BPF_JMP class.
A BPF_JMP32 insn needs to go through all checks that have been done on
BPF_JMP.
Also, verifier is doing runtime optimizations based on the extra info
conditional jump instruction could offer, especially when the comparison is
between constant and register that the value range of the register could be
improved based on the comparison results. These code are updated
accordingly.
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Instead of overwriting dead code with jmp -1 instructions
remove it completely for root. Adjust verifier state and
line info appropriately.
v2:
- adjust func_info (Alexei);
- make sure first instruction retains line info (Alexei).
v4: (Yonghong)
- remove unnecessary if (!insn to remove) checks;
- always keep last line info if first live instruction lacks one.
v5: (Martin Lau)
- improve and clarify comments.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In preparation for code removal change parameters to branch
and call adjustment functions to be more universal. The
current parameters assume we are patching a single instruction
with a longer set.
A diagram may help reading the change, this is for the patch
single case, patching instruction 1 with a replacement of 4:
____
0 |____|
1 |____| <-- pos ^
2 | | <-- end old ^ |
3 | | | delta | len
4 |____| | | (patch region)
5 | | <-- end new v v
6 |____|
end_old = pos + 1
end_new = pos + delta + 1
If we are before the patch region - curr variable and the target
are fully in old coordinates (hence comparing against end_old).
If we are after the region curr is in new coordinates (hence
the comparison to end_new) but target is in mixed coordinates,
so we just check if it falls before end_new, and if so it needs
the adjustment.
Note that we will not fix up branches which land in removed region
in case of removal, which should be okay, as we are only going to
remove dead code.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
For better performance analysis of BPF programs, this patch introduces
PERF_RECORD_BPF_EVENT, a new perf_event_type that exposes BPF program
load/unload information to user space.
Each BPF program may contain up to BPF_MAX_SUBPROGS (256) sub programs.
The following example shows kernel symbols for a BPF program with 7 sub
programs:
ffffffffa0257cf9 t bpf_prog_b07ccb89267cf242_F
ffffffffa02592e1 t bpf_prog_2dcecc18072623fc_F
ffffffffa025b0e9 t bpf_prog_bb7a405ebaec5d5c_F
ffffffffa025dd2c t bpf_prog_a7540d4a39ec1fc7_F
ffffffffa025fcca t bpf_prog_05762d4ade0e3737_F
ffffffffa026108f t bpf_prog_db4bd11e35df90d4_F
ffffffffa0263f00 t bpf_prog_89d64e4abf0f0126_F
ffffffffa0257cf9 t bpf_prog_ae31629322c4b018__dummy_tracepoi
When a bpf program is loaded, PERF_RECORD_KSYMBOL is generated for each
of these sub programs. Therefore, PERF_RECORD_BPF_EVENT is not needed
for simple profiling.
For annotation, user space need to listen to PERF_RECORD_BPF_EVENT and
gather more information about these (sub) programs via sys_bpf.
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradeaed.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@fb.com
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20190117161521.1341602-4-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Right now we are using BPF ax register in JIT for constant blinding as
well as in interpreter as temporary variable. Verifier will not be able
to use it simply because its use will get overridden from the former in
bpf_jit_blind_insn(). However, it can be made to work in that blinding
will be skipped if there is prior use in either source or destination
register on the instruction. Taking constraints of ax into account, the
verifier is then open to use it in rewrites under some constraints. Note,
ax register already has mappings in every eBPF JIT.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This change moves the on-stack 64 bit tmp variable in ___bpf_prog_run()
into the hidden ax register. The latter is currently only used in JITs
for constant blinding as a temporary scratch register, meaning the BPF
interpreter will never see the use of ax. Therefore it is safe to use
it for the cases where tmp has been used earlier. This is needed to later
on allow restricted hidden use of ax in both interpreter and JITs.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Lots of conflicts, by happily all cases of overlapping
changes, parallel adds, things of that nature.
Thanks to Stephen Rothwell, Saeed Mahameed, and others
for their guidance in these resolutions.
Signed-off-by: David S. Miller <davem@davemloft.net>
Michael and Sandipan report:
Commit ede95a63b5 introduced a bpf_jit_limit tuneable to limit BPF
JIT allocations. At compile time it defaults to PAGE_SIZE * 40000,
and is adjusted again at init time if MODULES_VADDR is defined.
For ppc64 kernels, MODULES_VADDR isn't defined, so we're stuck with
the compile-time default at boot-time, which is 0x9c400000 when
using 64K page size. This overflows the signed 32-bit bpf_jit_limit
value:
root@ubuntu:/tmp# cat /proc/sys/net/core/bpf_jit_limit
-1673527296
and can cause various unexpected failures throughout the network
stack. In one case `strace dhclient eth0` reported:
setsockopt(5, SOL_SOCKET, SO_ATTACH_FILTER, {len=11, filter=0x105dd27f8},
16) = -1 ENOTSUPP (Unknown error 524)
and similar failures can be seen with tools like tcpdump. This doesn't
always reproduce however, and I'm not sure why. The more consistent
failure I've seen is an Ubuntu 18.04 KVM guest booted on a POWER9
host would time out on systemd/netplan configuring a virtio-net NIC
with no noticeable errors in the logs.
Given this and also given that in near future some architectures like
arm64 will have a custom area for BPF JIT image allocations we should
get rid of the BPF_JIT_LIMIT_DEFAULT fallback / default entirely. For
4.21, we have an overridable bpf_jit_alloc_exec(), bpf_jit_free_exec()
so therefore add another overridable bpf_jit_alloc_exec_limit() helper
function which returns the possible size of the memory area for deriving
the default heuristic in bpf_jit_charge_init().
Like bpf_jit_alloc_exec() and bpf_jit_free_exec(), the new
bpf_jit_alloc_exec_limit() assumes that module_alloc() is the default
JIT memory provider, and therefore in case archs implement their custom
module_alloc() we use MODULES_{END,_VADDR} for limits and otherwise for
vmalloc_exec() cases like on ppc64 we use VMALLOC_{END,_START}.
Additionally, for archs supporting large page sizes, we should change
the sysctl to be handled as long to not run into sysctl restrictions
in future.
Fixes: ede95a63b5 ("bpf: add bpf_jit_limit knob to restrict unpriv allocations")
Reported-by: Sandipan Das <sandipan@linux.ibm.com>
Reported-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch adds bpf_line_info support.
It accepts an array of bpf_line_info objects during BPF_PROG_LOAD.
The "line_info", "line_info_cnt" and "line_info_rec_size" are added
to the "union bpf_attr". The "line_info_rec_size" makes
bpf_line_info extensible in the future.
The new "check_btf_line()" ensures the userspace line_info is valid
for the kernel to use.
When the verifier is translating/patching the bpf_prog (through
"bpf_patch_insn_single()"), the line_infos' insn_off is also
adjusted by the newly added "bpf_adj_linfo()".
If the bpf_prog is jited, this patch also provides the jited addrs (in
aux->jited_linfo) for the corresponding line_info.insn_off.
"bpf_prog_fill_jited_linfo()" is added to fill the aux->jited_linfo.
It is currently called by the x86 jit. Other jits can also use
"bpf_prog_fill_jited_linfo()" and it will be done in the followup patches.
In the future, if it deemed necessary, a particular jit could also provide
its own "bpf_prog_fill_jited_linfo()" implementation.
A few "*line_info*" fields are added to the bpf_prog_info such
that the user can get the xlated line_info back (i.e. the line_info
with its insn_off reflecting the translated prog). The jited_line_info
is available if the prog is jited. It is an array of __u64.
If the prog is not jited, jited_line_info_cnt is 0.
The verifier's verbose log with line_info will be done in
a follow up patch.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch implements interpreting BPF_ALU | BPF_ARSH. Do arithmetic right
shift on low 32-bit sub-register, and zero the high 32 bits.
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
1) When bpf_dump_raw_ok() == false and the kernel can provide >=1
func_info to the userspace, the current behavior is setting
the info.func_info_cnt to 0 instead of setting info.func_info
to 0.
It is different from the behavior in jited_func_lens/nr_jited_func_lens,
jited_ksyms/nr_jited_ksyms...etc.
This patch fixes it. (i.e. set func_info to 0 instead of
func_info_cnt to 0 when bpf_dump_raw_ok() == false).
2) When the userspace passed in info.func_info_cnt == 0, the kernel
will set the expected func_info size back to the
info.func_info_rec_size. It is a way for the userspace to learn
the kernel expected func_info_rec_size introduced in
commit 838e96904f ("bpf: Introduce bpf_func_info").
An exception is the kernel expected size is not set when
func_info is not available for a bpf_prog. This makes the
returned info.func_info_rec_size has different values
depending on the returned value of info.func_info_cnt.
This patch sets the kernel expected size to info.func_info_rec_size
independent of the info.func_info_cnt.
3) The current logic only rejects invalid func_info_rec_size if
func_info_cnt is non zero. This patch also rejects invalid
nonzero info.func_info_rec_size and not equal to the kernel
expected size.
4) Set info.btf_id as long as prog->aux->btf != NULL. That will
setup the later copy_to_user() codes look the same as others
which then easier to understand and maintain.
prog->aux->btf is not NULL only if prog->aux->func_info_cnt > 0.
Breaking up info.btf_id from prog->aux->func_info_cnt is needed
for the later line info patch anyway.
A similar change is made to bpf_get_prog_name().
Fixes: 838e96904f ("bpf: Introduce bpf_func_info")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
By default, BPF uses module_alloc() to allocate executable memory,
but this is not necessary on all arches and potentially undesirable
on some of them.
So break out the module_alloc() and module_memfree() calls into __weak
functions to allow them to be overridden in arch code.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Daniel Borkmann says:
====================
bpf-next 2018-11-30
The following pull-request contains BPF updates for your *net-next* tree.
(Getting out bit earlier this time to pull in a dependency from bpf.)
The main changes are:
1) Add libbpf ABI versioning and document API naming conventions
as well as ABI versioning process, from Andrey.
2) Add a new sk_msg_pop_data() helper for sk_msg based BPF
programs that is used in conjunction with sk_msg_push_data()
for adding / removing meta data to the msg data, from John.
3) Optimize convert_bpf_ld_abs() for 0 offset and fix various
lib and testsuite build failures on 32 bit, from David.
4) Make BPF prog dump for !JIT identical to how we dump subprogs
when JIT is in use, from Yonghong.
5) Rename btf_get_from_id() to make it more conform with libbpf
API naming conventions, from Martin.
6) Add a missing BPF kselftest config item, from Naresh.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Trivial conflict in net/core/filter.c, a locally computed
'sdif' is now an argument to the function.
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 838e96904f ("bpf: Introduce bpf_func_info")
added bpf func info support. The userspace is able
to get better ksym's for bpf programs with jit, and
is able to print out func prototypes.
For a program containing func-to-func calls, the existing
implementation returns user specified number of function
calls and BTF types if jit is enabled. If the jit is not
enabled, it only returns the type for the main function.
This is undesirable. Interpreter may still be used
and we should keep feature identical regardless of
whether jit is enabled or not.
This patch fixed this discrepancy.
Fixes: 838e96904f ("bpf: Introduce bpf_func_info")
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Make fetching of the BPF call address from ppc64 JIT generic. ppc64
was using a slightly different variant rather than through the insns'
imm field encoding as the target address would not fit into that space.
Therefore, the target subprog number was encoded into the insns' offset
and fetched through fp->aux->func[off]->bpf_func instead. Given there
are other JITs with this issue and the mechanism of fetching the address
is JIT-generic, move it into the core as a helper instead. On the JIT
side, we get information on whether the retrieved address is a fixed
one, that is, not changing through JIT passes, or a dynamic one. For
the former, JITs can optimize their imm emission because this doesn't
change jump offsets throughout JIT process.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Sandipan Das <sandipan@linux.ibm.com>
Tested-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch added interface to load a program with the following
additional information:
. prog_btf_fd
. func_info, func_info_rec_size and func_info_cnt
where func_info will provide function range and type_id
corresponding to each function.
The func_info_rec_size is introduced in the UAPI to specify
struct bpf_func_info size passed from user space. This
intends to make bpf_func_info structure growable in the future.
If the kernel gets a different bpf_func_info size from userspace,
it will try to handle user request with part of bpf_func_info
it can understand. In this patch, kernel can understand
struct bpf_func_info {
__u32 insn_offset;
__u32 type_id;
};
If user passed a bpf func_info record size of 16 bytes, the
kernel can still handle part of records with the above definition.
If verifier agrees with function range provided by the user,
the bpf_prog ksym for each function will use the func name
provided in the type_id, which is supposed to provide better
encoding as it is not limited by 16 bytes program name
limitation and this is better for bpf program which contains
multiple subprograms.
The bpf_prog_info interface is also extended to
return btf_id, func_info, func_info_rec_size and func_info_cnt
to userspace, so userspace can print out the function prototype
for each xlated function. The insn_offset in the returned
func_info corresponds to the insn offset for xlated functions.
With other jit related fields in bpf_prog_info, userspace can also
print out function prototypes for each jited function.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, /proc/kallsyms shows page address of jited bpf program. The
main reason here is to not expose randomized start address. However,
This is not ideal for detailed profiling (find hot instructions from
stack traces). This patch replaces the page address with real prog start
address.
This change is OK because these addresses are still protected by sysctl
kptr_restrict (see kallsyms_show_value()), and only programs loaded by
root are added to kallsyms (see bpf_prog_kallsyms_add()).
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Rick reported that the BPF JIT could potentially fill the entire module
space with BPF programs from unprivileged users which would prevent later
attempts to load normal kernel modules or privileged BPF programs, for
example. If JIT was enabled but unsuccessful to generate the image, then
before commit 290af86629 ("bpf: introduce BPF_JIT_ALWAYS_ON config")
we would always fall back to the BPF interpreter. Nowadays in the case
where the CONFIG_BPF_JIT_ALWAYS_ON could be set, then the load will abort
with a failure since the BPF interpreter was compiled out.
Add a global limit and enforce it for unprivileged users such that in case
of BPF interpreter compiled out we fail once the limit has been reached
or we fall back to BPF interpreter earlier w/o using module mem if latter
was compiled in. In a next step, fair share among unprivileged users can
be resolved in particular for the case where we would fail hard once limit
is reached.
Fixes: 290af86629 ("bpf: introduce BPF_JIT_ALWAYS_ON config")
Fixes: 0a14842f5a ("net: filter: Just In Time compiler for x86-64")
Co-Developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Queue/stack maps implement a FIFO/LIFO data storage for ebpf programs.
These maps support peek, pop and push operations that are exposed to eBPF
programs through the new bpf_map[peek/pop/push] helpers. Those operations
are exposed to userspace applications through the already existing
syscalls in the following way:
BPF_MAP_LOOKUP_ELEM -> peek
BPF_MAP_LOOKUP_AND_DELETE_ELEM -> pop
BPF_MAP_UPDATE_ELEM -> push
Queue/stack maps are implemented using a buffer, tail and head indexes,
hence BPF_F_NO_PREALLOC is not supported.
As opposite to other maps, queue and stack do not use RCU for protecting
maps values, the bpf_map[peek/pop] have a ARG_PTR_TO_UNINIT_MAP_VALUE
argument that is a pointer to a memory zone where to save the value of a
map. Basically the same as ARG_PTR_TO_UNINIT_MEM, but the size has not
be passed as an extra argument.
Our main motivation for implementing queue/stack maps was to keep track
of a pool of elements, like network ports in a SNAT, however we forsee
other use cases, like for exampling saving last N kernel events in a map
and then analysing from userspace.
Signed-off-by: Mauricio Vasquez B <mauricio.vasquez@polito.it>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a generic sk_msg layer, and convert current sockmap and later
kTLS over to make use of it. While sk_buff handles network packet
representation from netdevice up to socket, sk_msg handles data
representation from application to socket layer.
This means that sk_msg framework spans across ULP users in the
kernel, and enables features such as introspection or filtering
of data with the help of BPF programs that operate on this data
structure.
Latter becomes in particular useful for kTLS where data encryption
is deferred into the kernel, and as such enabling the kernel to
perform L7 introspection and policy based on BPF for TLS connections
where the record is being encrypted after BPF has run and came to
a verdict. In order to get there, first step is to transform open
coding of scatter-gather list handling into a common core framework
that subsystems can use.
The code itself has been split and refactored into three bigger
pieces: i) the generic sk_msg API which deals with managing the
scatter gather ring, providing helpers for walking and mangling,
transferring application data from user space into it, and preparing
it for BPF pre/post-processing, ii) the plain sock map itself
where sockets can be attached to or detached from; these bits
are independent of i) which can now be used also without sock
map, and iii) the integration with plain TCP as one protocol
to be used for processing L7 application data (later this could
e.g. also be extended to other protocols like UDP). The semantics
are the same with the old sock map code and therefore no change
of user facing behavior or APIs. While pursuing this work it
also helped finding a number of bugs in the old sockmap code
that we've fixed already in earlier commits. The test_sockmap
kselftest suite passes through fine as well.
Joint work with John.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit 394e40a297 ("bpf: extend bpf_prog_array to store pointers
to the cgroup storage") refactored the bpf_prog_array_copy_core()
to accommodate new structure bpf_prog_array_item which contains
bpf_prog array itself.
In the old code, we had
perf_event_query_prog_array():
mutex_lock(...)
bpf_prog_array_copy_call():
prog = rcu_dereference_check(array, 1)->progs
bpf_prog_array_copy_core(prog, ...)
mutex_unlock(...)
With the above commit, we had
perf_event_query_prog_array():
mutex_lock(...)
bpf_prog_array_copy_call():
bpf_prog_array_copy_core(array, ...):
item = rcu_dereference(array)->items;
...
mutex_unlock(...)
The new code will trigger a lockdep rcu checking warning.
The fix is to change rcu_dereference() to rcu_dereference_check()
to prevent such a warning.
Reported-by: syzbot+6e72317008eef84a216b@syzkaller.appspotmail.com
Fixes: 394e40a297 ("bpf: extend bpf_prog_array to store pointers to the cgroup storage")
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The bpf_get_local_storage() helper function is used
to get a pointer to the bpf local storage from a bpf program.
It takes a pointer to a storage map and flags as arguments.
Right now it accepts only cgroup storage maps, and flags
argument has to be 0. Further it can be extended to support
other types of local storage: e.g. thread local storage etc.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch converts bpf_prog_array from an array of prog pointers
to the array of struct bpf_prog_array_item elements.
This allows to save a cgroup storage pointer for each bpf program
efficiently attached to a cgroup.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Currently the return type of the bpf_prog_array_alloc() is
struct bpf_prog_array __rcu *, which is not quite correct.
Obviously, the returned pointer is a generic pointer, which
is valid for an indefinite amount of time and it's not shared
with anyone else, so there is no sense in marking it as __rcu.
This change eliminate the following sparse warnings:
kernel/bpf/core.c:1544:31: warning: incorrect type in return expression (different address spaces)
kernel/bpf/core.c:1544:31: expected struct bpf_prog_array [noderef] <asn:4>*
kernel/bpf/core.c:1544:31: got void *
kernel/bpf/core.c:1548:17: warning: incorrect type in return expression (different address spaces)
kernel/bpf/core.c:1548:17: expected struct bpf_prog_array [noderef] <asn:4>*
kernel/bpf/core.c:1548:17: got struct bpf_prog_array *<noident>
kernel/bpf/core.c:1681:15: warning: incorrect type in assignment (different address spaces)
kernel/bpf/core.c:1681:15: expected struct bpf_prog_array *array
kernel/bpf/core.c:1681:15: got struct bpf_prog_array [noderef] <asn:4>*
Fixes: 324bda9e6c ("bpf: multi program support for cgroup+bpf")
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Partially undo commit 9facc33687 ("bpf: reject any prog that failed
read-only lock") since it caused a regression, that is, syzkaller was
able to manage to cause a panic via fault injection deep in set_memory_ro()
path by letting an allocation fail: In x86's __change_page_attr_set_clr()
it was able to change the attributes of the primary mapping but not in
the alias mapping via cpa_process_alias(), so the second, inner call
to the __change_page_attr() via __change_page_attr_set_clr() had to split
a larger page and failed in the alloc_pages() with the artifically triggered
allocation error which is then propagated down to the call site.
Thus, for set_memory_ro() this means that it returned with an error, but
from debugging a probe_kernel_write() revealed EFAULT on that memory since
the primary mapping succeeded to get changed. Therefore the subsequent
hdr->locked = 0 reset triggered the panic as it was performed on read-only
memory, so call-site assumptions were infact wrong to assume that it would
either succeed /or/ not succeed at all since there's no such rollback in
set_memory_*() calls from partial change of mappings, in other words, we're
left in a state that is "half done". A later undo via set_memory_rw() is
succeeding though due to matching permissions on that part (aka due to the
try_preserve_large_page() succeeding). While reproducing locally with
explicitly triggering this error, the initial splitting only happens on
rare occasions and in real world it would additionally need oom conditions,
but that said, it could partially fail. Therefore, it is definitely wrong
to bail out on set_memory_ro() error and reject the program with the
set_memory_*() semantics we have today. Shouldn't have gone the extra mile
since no other user in tree today infact checks for any set_memory_*()
errors, e.g. neither module_enable_ro() / module_disable_ro() for module
RO/NX handling which is mostly default these days nor kprobes core with
alloc_insn_page() / free_insn_page() as examples that could be invoked long
after bootup and original 314beb9bca ("x86: bpf_jit_comp: secure bpf jit
against spraying attacks") did neither when it got first introduced to BPF
so "improving" with bailing out was clearly not right when set_memory_*()
cannot handle it today.
Kees suggested that if set_memory_*() can fail, we should annotate it with
__must_check, and all callers need to deal with it gracefully given those
set_memory_*() markings aren't "advisory", but they're expected to actually
do what they say. This might be an option worth to move forward in future
but would at the same time require that set_memory_*() calls from supporting
archs are guaranteed to be "atomic" in that they provide rollback if part
of the range fails, once that happened, the transition from RW -> RO could
be made more robust that way, while subsequent RO -> RW transition /must/
continue guaranteeing to always succeed the undo part.
Reported-by: syzbot+a4eb8c7766952a1ca872@syzkaller.appspotmail.com
Reported-by: syzbot+d866d1925855328eac3b@syzkaller.appspotmail.com
Fixes: 9facc33687 ("bpf: reject any prog that failed read-only lock")
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We currently lock any JITed image as read-only via bpf_jit_binary_lock_ro()
as well as the BPF image as read-only through bpf_prog_lock_ro(). In
the case any of these would fail we throw a WARN_ON_ONCE() in order to
yell loudly to the log. Perhaps, to some extend, this may be comparable
to an allocation where __GFP_NOWARN is explicitly not set.
Added via 65869a47f3 ("bpf: improve read-only handling"), this behavior
is slightly different compared to any of the other in-kernel set_memory_ro()
users who do not check the return code of set_memory_ro() and friends /at
all/ (e.g. in the case of module_enable_ro() / module_disable_ro()). Given
in BPF this is mandatory hardening step, we want to know whether there
are any issues that would leave both BPF data writable. So it happens
that syzkaller enabled fault injection and it triggered memory allocation
failure deep inside x86's change_page_attr_set_clr() which was triggered
from set_memory_ro().
Now, there are two options: i) leaving everything as is, and ii) reworking
the image locking code in order to have a final checkpoint out of the
central bpf_prog_select_runtime() which probes whether any of the calls
during prog setup weren't successful, and then bailing out with an error.
Option ii) is a better approach since this additional paranoia avoids
altogether leaving any potential W+X pages from BPF side in the system.
Therefore, lets be strict about it, and reject programs in such unlikely
occasion. While testing I noticed also that one bpf_prog_lock_ro()
call was missing on the outer dummy prog in case of calls, e.g. in the
destructor we call bpf_prog_free_deferred() on the main prog where we
try to bpf_prog_unlock_free() the program, and since we go via
bpf_prog_select_runtime() do that as well.
Reported-by: syzbot+3b889862e65a98317058@syzkaller.appspotmail.com
Reported-by: syzbot+9e762b52dd17e616a7a5@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
While testing I found that when hitting error path in bpf_prog_load()
where we jump to free_used_maps and prog contained BPF to BPF calls
that were JITed earlier, then we never clean up the bpf_prog_kallsyms_add()
done under jit_subprogs(). Add proper API to make BPF kallsyms deletion
more clear and fix that.
Fixes: 1c2a088a66 ("bpf: x64: add JIT support for multi-function programs")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf has been used extensively for tracing. For example, bcc
contains an almost full set of bpf-based tools to trace kernel
and user functions/events. Most tracing tools are currently
either filtered based on pid or system-wide.
Containers have been used quite extensively in industry and
cgroup is often used together to provide resource isolation
and protection. Several processes may run inside the same
container. It is often desirable to get container-level tracing
results as well, e.g. syscall count, function count, I/O
activity, etc.
This patch implements a new helper, bpf_get_current_cgroup_id(),
which will return cgroup id based on the cgroup within which
the current task is running.
The later patch will provide an example to show that
userspace can get the same cgroup id so it could
configure a filter or policy in the bpf program based on
task cgroup id.
The helper is currently implemented for tracing. It can
be added to other program types as well when needed.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This makes is it possible for bpf prog detach to return -ENOENT.
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
S390 bpf_jit.S is removed in net-next and had changes in 'net',
since that code isn't used any more take the removal.
TLS data structures split the TX and RX components in 'net-next',
put the new struct members from the bug fix in 'net' into the RX
part.
The 'net-next' tree had some reworking of how the ERSPAN code works in
the GRE tunneling code, overlapping with a one-line headroom
calculation fix in 'net'.
Overlapping changes in __sock_map_ctx_update_elem(), keep the bits
that read the prog members via READ_ONCE() into local variables
before using them.
Signed-off-by: David S. Miller <davem@davemloft.net>
Recently during testing, I ran into the following panic:
[ 207.892422] Internal error: Accessing user space memory outside uaccess.h routines: 96000004 [#1] SMP
[ 207.901637] Modules linked in: binfmt_misc [...]
[ 207.966530] CPU: 45 PID: 2256 Comm: test_verifier Tainted: G W 4.17.0-rc3+ #7
[ 207.974956] Hardware name: FOXCONN R2-1221R-A4/C2U4N_MB, BIOS G31FB18A 03/31/2017
[ 207.982428] pstate: 60400005 (nZCv daif +PAN -UAO)
[ 207.987214] pc : bpf_skb_load_helper_8_no_cache+0x34/0xc0
[ 207.992603] lr : 0xffff000000bdb754
[ 207.996080] sp : ffff000013703ca0
[ 207.999384] x29: ffff000013703ca0 x28: 0000000000000001
[ 208.004688] x27: 0000000000000001 x26: 0000000000000000
[ 208.009992] x25: ffff000013703ce0 x24: ffff800fb4afcb00
[ 208.015295] x23: ffff00007d2f5038 x22: ffff00007d2f5000
[ 208.020599] x21: fffffffffeff2a6f x20: 000000000000000a
[ 208.025903] x19: ffff000009578000 x18: 0000000000000a03
[ 208.031206] x17: 0000000000000000 x16: 0000000000000000
[ 208.036510] x15: 0000ffff9de83000 x14: 0000000000000000
[ 208.041813] x13: 0000000000000000 x12: 0000000000000000
[ 208.047116] x11: 0000000000000001 x10: ffff0000089e7f18
[ 208.052419] x9 : fffffffffeff2a6f x8 : 0000000000000000
[ 208.057723] x7 : 000000000000000a x6 : 00280c6160000000
[ 208.063026] x5 : 0000000000000018 x4 : 0000000000007db6
[ 208.068329] x3 : 000000000008647a x2 : 19868179b1484500
[ 208.073632] x1 : 0000000000000000 x0 : ffff000009578c08
[ 208.078938] Process test_verifier (pid: 2256, stack limit = 0x0000000049ca7974)
[ 208.086235] Call trace:
[ 208.088672] bpf_skb_load_helper_8_no_cache+0x34/0xc0
[ 208.093713] 0xffff000000bdb754
[ 208.096845] bpf_test_run+0x78/0xf8
[ 208.100324] bpf_prog_test_run_skb+0x148/0x230
[ 208.104758] sys_bpf+0x314/0x1198
[ 208.108064] el0_svc_naked+0x30/0x34
[ 208.111632] Code: 91302260 f9400001 f9001fa1 d2800001 (29500680)
[ 208.117717] ---[ end trace 263cb8a59b5bf29f ]---
The program itself which caused this had a long jump over the whole
instruction sequence where all of the inner instructions required
heavy expansions into multiple BPF instructions. Additionally, I also
had BPF hardening enabled which requires once more rewrites of all
constant values in order to blind them. Each time we rewrite insns,
bpf_adj_branches() would need to potentially adjust branch targets
which cross the patchlet boundary to accommodate for the additional
delta. Eventually that lead to the case where the target offset could
not fit into insn->off's upper 0x7fff limit anymore where then offset
wraps around becoming negative (in s16 universe), or vice versa
depending on the jump direction.
Therefore it becomes necessary to detect and reject any such occasions
in a generic way for native eBPF and cBPF to eBPF migrations. For
the latter we can simply check bounds in the bpf_convert_filter()'s
BPF_EMIT_JMP helper macro and bail out once we surpass limits. The
bpf_patch_insn_single() for native eBPF (and cBPF to eBPF in case
of subsequent hardening) is a bit more complex in that we need to
detect such truncations before hitting the bpf_prog_realloc(). Thus
the latter is split into an extra pass to probe problematic offsets
on the original program in order to fail early. With that in place
and carefully tested I no longer hit the panic and the rewrites are
rejected properly. The above example panic I've seen on bpf-next,
though the issue itself is generic in that a guard against this issue
in bpf seems more appropriate in this case.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Sockmap is currently backed by an array and enforces keys to be
four bytes. This works well for many use cases and was originally
modeled after devmap which also uses four bytes keys. However,
this has become limiting in larger use cases where a hash would
be more appropriate. For example users may want to use the 5-tuple
of the socket as the lookup key.
To support this add hash support.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
bpf_event_output() is useful for offloads to add events to BPF
event rings, export it. Note that export is placed near the stub
since tracing is optional and kernel/bpf/core.c is always going
to be built.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The main part of this work is to finally allow removal of LD_ABS
and LD_IND from the BPF core by reimplementing them through native
eBPF instead. Both LD_ABS/LD_IND were carried over from cBPF and
keeping them around in native eBPF caused way more trouble than
actually worth it. To just list some of the security issues in
the past:
* fdfaf64e75 ("x86: bpf_jit: support negative offsets")
* 35607b02db ("sparc: bpf_jit: fix loads from negative offsets")
* e0ee9c1215 ("x86: bpf_jit: fix two bugs in eBPF JIT compiler")
* 07aee94394 ("bpf, sparc: fix usage of wrong reg for load_skb_regs after call")
* 6d59b7dbf7 ("bpf, s390x: do not reload skb pointers in non-skb context")
* 87338c8e2c ("bpf, ppc64: do not reload skb pointers in non-skb context")
For programs in native eBPF, LD_ABS/LD_IND are pretty much legacy
these days due to their limitations and more efficient/flexible
alternatives that have been developed over time such as direct
packet access. LD_ABS/LD_IND only cover 1/2/4 byte loads into a
register, the load happens in host endianness and its exception
handling can yield unexpected behavior. The latter is explained
in depth in f6b1b3bf0d ("bpf: fix subprog verifier bypass by
div/mod by 0 exception") with similar cases of exceptions we had.
In native eBPF more recent program types will disable LD_ABS/LD_IND
altogether through may_access_skb() in verifier, and given the
limitations in terms of exception handling, it's also disabled
in programs that use BPF to BPF calls.
In terms of cBPF, the LD_ABS/LD_IND is used in networking programs
to access packet data. It is not used in seccomp-BPF but programs
that use it for socket filtering or reuseport for demuxing with
cBPF. This is mostly relevant for applications that have not yet
migrated to native eBPF.
The main complexity and source of bugs in LD_ABS/LD_IND is coming
from their implementation in the various JITs. Most of them keep
the model around from cBPF times by implementing a fastpath written
in asm. They use typically two from the BPF program hidden CPU
registers for caching the skb's headlen (skb->len - skb->data_len)
and skb->data. Throughout the JIT phase this requires to keep track
whether LD_ABS/LD_IND are used and if so, the two registers need
to be recached each time a BPF helper would change the underlying
packet data in native eBPF case. At least in eBPF case, available
CPU registers are rare and the additional exit path out of the
asm written JIT helper makes it also inflexible since not all
parts of the JITer are in control from plain C. A LD_ABS/LD_IND
implementation in eBPF therefore allows to significantly reduce
the complexity in JITs with comparable performance results for
them, e.g.:
test_bpf tcpdump port 22 tcpdump complex
x64 - before 15 21 10 14 19 18
- after 7 10 10 7 10 15
arm64 - before 40 91 92 40 91 151
- after 51 64 73 51 62 113
For cBPF we now track any usage of LD_ABS/LD_IND in bpf_convert_filter()
and cache the skb's headlen and data in the cBPF prologue. The
BPF_REG_TMP gets remapped from R8 to R2 since it's mainly just
used as a local temporary variable. This allows to shrink the
image on x86_64 also for seccomp programs slightly since mapping
to %rsi is not an ereg. In callee-saved R8 and R9 we now track
skb data and headlen, respectively. For normal prologue emission
in the JITs this does not add any extra instructions since R8, R9
are pushed to stack in any case from eBPF side. cBPF uses the
convert_bpf_ld_abs() emitter which probes the fast path inline
already and falls back to bpf_skb_load_helper_{8,16,32}() helper
relying on the cached skb data and headlen as well. R8 and R9
never need to be reloaded due to bpf_helper_changes_pkt_data()
since all skb access in cBPF is read-only. Then, for the case
of native eBPF, we use the bpf_gen_ld_abs() emitter, which calls
the bpf_skb_load_helper_{8,16,32}_no_cache() helper unconditionally,
does neither cache skb data and headlen nor has an inlined fast
path. The reason for the latter is that native eBPF does not have
any extra registers available anyway, but even if there were, it
avoids any reload of skb data and headlen in the first place.
Additionally, for the negative offsets, we provide an alternative
bpf_skb_load_bytes_relative() helper in eBPF which operates
similarly as bpf_skb_load_bytes() and allows for more flexibility.
Tested myself on x64, arm64, s390x, from Sandipan on ppc64.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
tracepoints to bpf core were added as a way to provide introspection
to bpf programs and maps, but after some time it became clear that
this approach is inadequate, so prog_id, map_id and corresponding
get_next_id, get_fd_by_id, get_info_by_fd, prog_query APIs were
introduced and fully adopted by bpftool and other applications.
The tracepoints in bpf core started to rot and causing syzbot warnings:
WARNING: CPU: 0 PID: 3008 at kernel/trace/trace_event_perf.c:274
Kernel panic - not syncing: panic_on_warn set ...
perf_trace_bpf_map_keyval+0x260/0xbd0 include/trace/events/bpf.h:228
trace_bpf_map_update_elem include/trace/events/bpf.h:274 [inline]
map_update_elem kernel/bpf/syscall.c:597 [inline]
SYSC_bpf kernel/bpf/syscall.c:1478 [inline]
Hence this patch deletes tracepoints in bpf core.
Reported-by: Eric Biggers <ebiggers3@gmail.com>
Reported-by: syzbot <bot+a9dbb3c3e64b62536a4bc5ee7bbd4ca627566188@syzkaller.appspotmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Currently, stackmap and bpf_get_stackid helper are provided
for bpf program to get the stack trace. This approach has
a limitation though. If two stack traces have the same hash,
only one will get stored in the stackmap table,
so some stack traces are missing from user perspective.
This patch implements a new helper, bpf_get_stack, will
send stack traces directly to bpf program. The bpf program
is able to see all stack traces, and then can do in-kernel
processing or send stack traces to user space through
shared map or bpf_perf_event_output.
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
syzbot reported a possible deadlock in perf_event_detach_bpf_prog.
The error details:
======================================================
WARNING: possible circular locking dependency detected
4.16.0-rc7+ #3 Not tainted
------------------------------------------------------
syz-executor7/24531 is trying to acquire lock:
(bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854
but task is already holding lock:
(&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&mm->mmap_sem){++++}:
__might_fault+0x13a/0x1d0 mm/memory.c:4571
_copy_to_user+0x2c/0xc0 lib/usercopy.c:25
copy_to_user include/linux/uaccess.h:155 [inline]
bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694
perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891
_perf_ioctl kernel/events/core.c:4750 [inline]
perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770
vfs_ioctl fs/ioctl.c:46 [inline]
do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7
-> #0 (bpf_event_mutex){+.+.}:
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854
perf_event_free_bpf_prog kernel/events/core.c:8147 [inline]
_free_event+0xbdb/0x10f0 kernel/events/core.c:4116
put_event+0x24/0x30 kernel/events/core.c:4204
perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172
remove_vma+0xb4/0x1b0 mm/mmap.c:172
remove_vma_list mm/mmap.c:2490 [inline]
do_munmap+0x82a/0xdf0 mm/mmap.c:2731
mmap_region+0x59e/0x15a0 mm/mmap.c:1646
do_mmap+0x6c0/0xe00 mm/mmap.c:1483
do_mmap_pgoff include/linux/mm.h:2223 [inline]
vm_mmap_pgoff+0x1de/0x280 mm/util.c:355
SYSC_mmap_pgoff mm/mmap.c:1533 [inline]
SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491
SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91
do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&mm->mmap_sem);
lock(bpf_event_mutex);
lock(&mm->mmap_sem);
lock(bpf_event_mutex);
*** DEADLOCK ***
======================================================
The bug is introduced by Commit f371b304f1 ("bpf/tracing: allow
user space to query prog array on the same tp") where copy_to_user,
which requires mm->mmap_sem, is called inside bpf_event_mutex lock.
At the same time, during perf_event file descriptor close,
mm->mmap_sem is held first and then subsequent
perf_event_detach_bpf_prog needs bpf_event_mutex lock.
Such a senario caused a deadlock.
As suggested by Daniel, moving copy_to_user out of the
bpf_event_mutex lock should fix the problem.
Fixes: f371b304f1 ("bpf/tracing: allow user space to query prog array on the same tp")
Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
syzkaller tried to perform a prog query in perf_event_query_prog_array()
where struct perf_event_query_bpf had an ids_len of 1,073,741,353 and
thus causing a warning due to failed kcalloc() allocation out of the
bpf_prog_array_copy_to_user() helper. Given we cannot attach more than
64 programs to a perf event, there's no point in allowing huge ids_len.
Therefore, allow a buffer that would fix the maximum number of ids and
also add a __GFP_NOWARN to the temporary ids buffer.
Fixes: f371b304f1 ("bpf/tracing: allow user space to query prog array on the same tp")
Fixes: 0911287ce3 ("bpf: fix bpf_prog_array_copy_to_user() issues")
Reported-by: syzbot+cab5816b0edbabf598b3@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
1. move copy_to_user out of rcu section to fix the following issue:
./include/linux/rcupdate.h:302 Illegal context switch in RCU read-side critical section!
stack backtrace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4592
rcu_preempt_sleep_check include/linux/rcupdate.h:301 [inline]
___might_sleep+0x385/0x470 kernel/sched/core.c:6079
__might_sleep+0x95/0x190 kernel/sched/core.c:6067
__might_fault+0xab/0x1d0 mm/memory.c:4532
_copy_to_user+0x2c/0xc0 lib/usercopy.c:25
copy_to_user include/linux/uaccess.h:155 [inline]
bpf_prog_array_copy_to_user+0x217/0x4d0 kernel/bpf/core.c:1587
bpf_prog_array_copy_info+0x17b/0x1c0 kernel/bpf/core.c:1685
perf_event_query_prog_array+0x196/0x280 kernel/trace/bpf_trace.c:877
_perf_ioctl kernel/events/core.c:4737 [inline]
perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4757
2. move *prog under rcu, since it's not ok to dereference it afterwards
3. in a rare case of prog array being swapped between bpf_prog_array_length()
and bpf_prog_array_copy_to_user() calls make sure to copy zeros to user space,
so the user doesn't walk over uninited prog_ids while kernel reported
uattr->query.prog_cnt > 0
Reported-by: syzbot+7dbcd2d3b85f9b608b23@syzkaller.appspotmail.com
Fixes: 468e2f64d2 ("bpf: introduce BPF_PROG_QUERY command")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
One of the ugly leftovers from the early eBPF days is that div/mod
operations based on registers have a hard-coded src_reg == 0 test
in the interpreter as well as in JIT code generators that would
return from the BPF program with exit code 0. This was basically
adopted from cBPF interpreter for historical reasons.
There are multiple reasons why this is very suboptimal and prone
to bugs. To name one: the return code mapping for such abnormal
program exit of 0 does not always match with a suitable program
type's exit code mapping. For example, '0' in tc means action 'ok'
where the packet gets passed further up the stack, which is just
undesirable for such cases (e.g. when implementing policy) and
also does not match with other program types.
While trying to work out an exception handling scheme, I also
noticed that programs crafted like the following will currently
pass the verifier:
0: (bf) r6 = r1
1: (85) call pc+8
caller:
R6=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
callee:
frame1: R1=ctx(id=0,off=0,imm=0) R10=fp0,call_1
10: (b4) (u32) r2 = (u32) 0
11: (b4) (u32) r3 = (u32) 1
12: (3c) (u32) r3 /= (u32) r2
13: (61) r0 = *(u32 *)(r1 +76)
14: (95) exit
returning from callee:
frame1: R0_w=pkt(id=0,off=0,r=0,imm=0)
R1=ctx(id=0,off=0,imm=0) R2_w=inv0
R3_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff))
R10=fp0,call_1
to caller at 2:
R0_w=pkt(id=0,off=0,r=0,imm=0) R6=ctx(id=0,off=0,imm=0)
R10=fp0,call_-1
from 14 to 2: R0=pkt(id=0,off=0,r=0,imm=0)
R6=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
2: (bf) r1 = r6
3: (61) r1 = *(u32 *)(r1 +80)
4: (bf) r2 = r0
5: (07) r2 += 8
6: (2d) if r2 > r1 goto pc+1
R0=pkt(id=0,off=0,r=8,imm=0) R1=pkt_end(id=0,off=0,imm=0)
R2=pkt(id=0,off=8,r=8,imm=0) R6=ctx(id=0,off=0,imm=0)
R10=fp0,call_-1
7: (71) r0 = *(u8 *)(r0 +0)
8: (b7) r0 = 1
9: (95) exit
from 6 to 8: safe
processed 16 insns (limit 131072), stack depth 0+0
Basically what happens is that in the subprog we make use of a
div/mod by 0 exception and in the 'normal' subprog's exit path
we just return skb->data back to the main prog. This has the
implication that the verifier thinks we always get a pkt pointer
in R0 while we still have the implicit 'return 0' from the div
as an alternative unconditional return path earlier. Thus, R0
then contains 0, meaning back in the parent prog we get the
address range of [0x0, skb->data_end] as read and writeable.
Similar can be crafted with other pointer register types.
Since i) BPF_ABS/IND is not allowed in programs that contain
BPF to BPF calls (and generally it's also disadvised to use in
native eBPF context), ii) unknown opcodes don't return zero
anymore, iii) we don't return an exception code in dead branches,
the only last missing case affected and to fix is the div/mod
handling.
What we would really need is some infrastructure to propagate
exceptions all the way to the original prog unwinding the
current stack and returning that code to the caller of the
BPF program. In user space such exception handling for similar
runtimes is typically implemented with setjmp(3) and longjmp(3)
as one possibility which is not available in the kernel,
though (kgdb used to implement it in kernel long time ago). I
implemented a PoC exception handling mechanism into the BPF
interpreter with porting setjmp()/longjmp() into x86_64 and
adding a new internal BPF_ABRT opcode that can use a program
specific exception code for all exception cases we have (e.g.
div/mod by 0, unknown opcodes, etc). While this seems to work
in the constrained BPF environment (meaning, here, we don't
need to deal with state e.g. from memory allocations that we
would need to undo before going into exception state), it still
has various drawbacks: i) we would need to implement the
setjmp()/longjmp() for every arch supported in the kernel and
for x86_64, arm64, sparc64 JITs currently supporting calls,
ii) it has unconditional additional cost on main program
entry to store CPU register state in initial setjmp() call,
and we would need some way to pass the jmp_buf down into
___bpf_prog_run() for main prog and all subprogs, but also
storing on stack is not really nice (other option would be
per-cpu storage for this, but it also has the drawback that
we need to disable preemption for every BPF program types).
All in all this approach would add a lot of complexity.
Another poor-man's solution would be to have some sort of
additional shared register or scratch buffer to hold state
for exceptions, and test that after every call return to
chain returns and pass R0 all the way down to BPF prog caller.
This is also problematic in various ways: i) an additional
register doesn't map well into JITs, and some other scratch
space could only be on per-cpu storage, which, again has the
side-effect that this only works when we disable preemption,
or somewhere in the input context which is not available
everywhere either, and ii) this adds significant runtime
overhead by putting conditionals after each and every call,
as well as implementation complexity.
Yet another option is to teach verifier that div/mod can
return an integer, which however is also complex to implement
as verifier would need to walk such fake 'mov r0,<code>; exit;'
sequeuence and there would still be no guarantee for having
propagation of this further down to the BPF caller as proper
exception code. For parent prog, it is also is not distinguishable
from a normal return of a constant scalar value.
The approach taken here is a completely different one with
little complexity and no additional overhead involved in
that we make use of the fact that a div/mod by 0 is undefined
behavior. Instead of bailing out, we adapt the same behavior
as on some major archs like ARMv8 [0] into eBPF as well:
X div 0 results in 0, and X mod 0 results in X. aarch64 and
aarch32 ISA do not generate any traps or otherwise aborts
of program execution for unsigned divides. I verified this
also with a test program compiled by gcc and clang, and the
behavior matches with the spec. Going forward we adapt the
eBPF verifier to emit such rewrites once div/mod by register
was seen. cBPF is not touched and will keep existing 'return 0'
semantics. Given the options, it seems the most suitable from
all of them, also since major archs have similar schemes in
place. Given this is all in the realm of undefined behavior,
we still have the option to adapt if deemed necessary and
this way we would also have the option of more flexibility
from LLVM code generation side (which is then fully visible
to verifier). Thus, this patch i) fixes the panic seen in
above program and ii) doesn't bypass the verifier observations.
[0] ARM Architecture Reference Manual, ARMv8 [ARM DDI 0487B.b]
http://infocenter.arm.com/help/topic/com.arm.doc.ddi0487b.b/DDI0487B_b_armv8_arm.pdf
1) aarch64 instruction set: section C3.4.7 and C6.2.279 (UDIV)
"A division by zero results in a zero being written to
the destination register, without any indication that
the division by zero occurred."
2) aarch32 instruction set: section F1.4.8 and F5.1.263 (UDIV)
"For the SDIV and UDIV instructions, division by zero
always returns a zero result."
Fixes: f4d7e40a5b ("bpf: introduce function calls (verification)")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Recent findings by syzcaller fixed in 7891a87efc ("bpf: arsh is
not supported in 32 bit alu thus reject it") triggered a warning
in the interpreter due to unknown opcode not being rejected by
the verifier. The 'return 0' for an unknown opcode is really not
optimal, since with BPF to BPF calls, this would go untracked by
the verifier.
Do two things here to improve the situation: i) perform basic insn
sanity check early on in the verification phase and reject every
non-uapi insn right there. The bpf_opcode_in_insntable() table
reuses the same mapping as the jumptable in ___bpf_prog_run() sans
the non-public mappings. And ii) in ___bpf_prog_run() we do need
to BUG in the case where the verifier would ever create an unknown
opcode due to some rewrites.
Note that JITs do not have such issues since they would punt to
interpreter in these situations. Moreover, the BPF_JIT_ALWAYS_ON
would also help to avoid such unknown opcodes in the first place.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Alexei Starovoitov says:
====================
pull-request: bpf-next 2018-01-19
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) bpf array map HW offload, from Jakub.
2) support for bpf_get_next_key() for LPM map, from Yonghong.
3) test_verifier now runs loaded programs, from Alexei.
4) xdp cpumap monitoring, from Jesper.
5) variety of tests, cleanups and small x64 JIT optimization, from Daniel.
6) user space can now retrieve HW JITed program, from Jiong.
Note there is a minor conflict between Russell's arm32 JIT fixes
and removal of bpf_jit_enable variable by Daniel which should
be resolved by keeping Russell's comment and removing that variable.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
The BPF verifier conflict was some minor contextual issue.
The TUN conflict was less trivial. Cong Wang fixed a memory leak of
tfile->tx_array in 'net'. This is an skb_array. But meanwhile in
net-next tun changed tfile->tx_arry into tfile->tx_ring which is a
ptr_ring.
Signed-off-by: David S. Miller <davem@davemloft.net>
Having a pure_initcall() callback just to permanently enable BPF
JITs under CONFIG_BPF_JIT_ALWAYS_ON is unnecessary and could leave
a small race window in future where JIT is still disabled on boot.
Since we know about the setting at compilation time anyway, just
initialize it properly there. Also consolidate all the individual
bpf_jit_enable variables into a single one and move them under one
location. Moreover, don't allow for setting unspecified garbage
values on them.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Divides by zero are not nice, lets avoid them if possible.
Also do_div() seems not needed when dealing with 32bit operands,
but this seems a minor detail.
Fixes: bd4cf0ed33 ("net: filter: rework/optimize internal BPF interpreter's instruction set")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF alignment tests got a conflict because the registers
are output as Rn_w instead of just Rn in net-next, and
in net a fixup for a testcase prohibits logical operations
on pointers before using them.
Also, we should attempt to patch BPF call args if JIT always on is
enabled. Instead, if we fail to JIT the subprogs we should pass
an error back up and fail immediately.
Signed-off-by: David S. Miller <davem@davemloft.net>
The BPF interpreter has been used as part of the spectre 2 attack CVE-2017-5715.
A quote from goolge project zero blog:
"At this point, it would normally be necessary to locate gadgets in
the host kernel code that can be used to actually leak data by reading
from an attacker-controlled location, shifting and masking the result
appropriately and then using the result of that as offset to an
attacker-controlled address for a load. But piecing gadgets together
and figuring out which ones work in a speculation context seems annoying.
So instead, we decided to use the eBPF interpreter, which is built into
the host kernel - while there is no legitimate way to invoke it from inside
a VM, the presence of the code in the host kernel's text section is sufficient
to make it usable for the attack, just like with ordinary ROP gadgets."
To make attacker job harder introduce BPF_JIT_ALWAYS_ON config
option that removes interpreter from the kernel in favor of JIT-only mode.
So far eBPF JIT is supported by:
x64, arm64, arm32, sparc64, s390, powerpc64, mips64
The start of JITed program is randomized and code page is marked as read-only.
In addition "constant blinding" can be turned on with net.core.bpf_jit_harden
v2->v3:
- move __bpf_prog_ret0 under ifdef (Daniel)
v1->v2:
- fix init order, test_bpf and cBPF (Daniel's feedback)
- fix offloaded bpf (Jakub's feedback)
- add 'return 0' dummy in case something can invoke prog->bpf_func
- retarget bpf tree. For bpf-next the patch would need one extra hunk.
It will be sent when the trees are merged back to net-next
Considered doing:
int bpf_jit_enable __read_mostly = BPF_EBPF_JIT_DEFAULT;
but it seems better to land the patch as-is and in bpf-next remove
bpf_jit_enable global variable from all JITs, consolidate in one place
and remove this jit_init() function.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Typical JIT does several passes over bpf instructions to
compute total size and relative offsets of jumps and calls.
With multitple bpf functions calling each other all relative calls
will have invalid offsets intially therefore we need to additional
last pass over the program to emit calls with correct offsets.
For example in case of three bpf functions:
main:
call foo
call bpf_map_lookup
exit
foo:
call bar
exit
bar:
exit
We will call bpf_int_jit_compile() indepedently for main(), foo() and bar()
x64 JIT typically does 4-5 passes to converge.
After these initial passes the image for these 3 functions
will be good except call targets, since start addresses of
foo() and bar() are unknown when we were JITing main()
(note that call bpf_map_lookup will be resolved properly
during initial passes).
Once start addresses of 3 functions are known we patch
call_insn->imm to point to right functions and call
bpf_int_jit_compile() again which needs only one pass.
Additional safety checks are done to make sure this
last pass doesn't produce image that is larger or smaller
than previous pass.
When constant blinding is on it's applied to all functions
at the first pass, since doing it once again at the last
pass can change size of the JITed code.
Tested on x64 and arm64 hw with JIT on/off, blinding on/off.
x64 jits bpf-to-bpf calls correctly while arm64 falls back to interpreter.
All other JITs that support normal BPF_CALL will behave the same way
since bpf-to-bpf call is equivalent to bpf-to-kernel call from
JITs point of view.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
global bpf_jit_enable variable is tested multiple times in JITs,
blinding and verifier core. The malicious root can try to toggle
it while loading the programs. This race condition was accounted
for and there should be no issues, but it's safer to avoid
this race condition.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
though bpf_call is still the same call instruction and
calling convention 'bpf to bpf' and 'bpf to helper' is the same
the interpreter has to oparate on 'struct bpf_insn *'.
To distinguish these two cases add a kernel internal opcode and
mark call insns with it.
This opcode is seen by interpreter only. JITs will never see it.
Also add tiny bit of debug code to aid interpreter debugging.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Error injection is sloppy and very ad-hoc. BPF could fill this niche
perfectly with it's kprobe functionality. We could make sure errors are
only triggered in specific call chains that we care about with very
specific situations. Accomplish this with the bpf_override_funciton
helper. This will modify the probe'd callers return value to the
specified value and set the PC to an override function that simply
returns, bypassing the originally probed function. This gives us a nice
clean way to implement systematic error injection for all of our code
paths.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit e87c6bc385 ("bpf: permit multiple bpf attachments
for a single perf event") added support to attach multiple
bpf programs to a single perf event.
Although this provides flexibility, users may want to know
what other bpf programs attached to the same tp interface.
Besides getting visibility for the underlying bpf system,
such information may also help consolidate multiple bpf programs,
understand potential performance issues due to a large array,
and debug (e.g., one bpf program which overwrites return code
may impact subsequent program results).
Commit 2541517c32 ("tracing, perf: Implement BPF programs
attached to kprobes") utilized the existing perf ioctl
interface and added the command PERF_EVENT_IOC_SET_BPF
to attach a bpf program to a tracepoint. This patch adds a new
ioctl command, given a perf event fd, to query the bpf program
array attached to the same perf tracepoint event.
The new uapi ioctl command:
PERF_EVENT_IOC_QUERY_BPF
The new uapi/linux/perf_event.h structure:
struct perf_event_query_bpf {
__u32 ids_len;
__u32 prog_cnt;
__u32 ids[0];
};
User space provides buffer "ids" for kernel to copy to.
When returning from the kernel, the number of available
programs in the array is set in "prog_cnt".
The usage:
struct perf_event_query_bpf *query =
malloc(sizeof(*query) + sizeof(u32) * ids_len);
query.ids_len = ids_len;
err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query);
if (err == 0) {
/* query.prog_cnt is the number of available progs,
* number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt
*/
} else if (errno == ENOSPC) {
/* query.ids_len number of progs copied,
* query.prog_cnt is the number of available progs
*/
} else {
/* other errors */
}
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
cgropu+bpf prog array has a maximum number of 64 programs.
Let us apply the same limit here.
Fixes: e87c6bc385 ("bpf: permit multiple bpf attachments for a single perf event")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Merge updates from Andrew Morton:
- a few misc bits
- ocfs2 updates
- almost all of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (131 commits)
memory hotplug: fix comments when adding section
mm: make alloc_node_mem_map a void call if we don't have CONFIG_FLAT_NODE_MEM_MAP
mm: simplify nodemask printing
mm,oom_reaper: remove pointless kthread_run() error check
mm/page_ext.c: check if page_ext is not prepared
writeback: remove unused function parameter
mm: do not rely on preempt_count in print_vma_addr
mm, sparse: do not swamp log with huge vmemmap allocation failures
mm/hmm: remove redundant variable align_end
mm/list_lru.c: mark expected switch fall-through
mm/shmem.c: mark expected switch fall-through
mm/page_alloc.c: broken deferred calculation
mm: don't warn about allocations which stall for too long
fs: fuse: account fuse_inode slab memory as reclaimable
mm, page_alloc: fix potential false positive in __zone_watermark_ok
mm: mlock: remove lru_add_drain_all()
mm, sysctl: make NUMA stats configurable
shmem: convert shmem_init_inodecache() to void
Unify migrate_pages and move_pages access checks
mm, pagevec: rename pagevec drained field
...
Patch series "kmemcheck: kill kmemcheck", v2.
As discussed at LSF/MM, kill kmemcheck.
KASan is a replacement that is able to work without the limitation of
kmemcheck (single CPU, slow). KASan is already upstream.
We are also not aware of any users of kmemcheck (or users who don't
consider KASan as a suitable replacement).
The only objection was that since KASAN wasn't supported by all GCC
versions provided by distros at that time we should hold off for 2
years, and try again.
Now that 2 years have passed, and all distros provide gcc that supports
KASAN, kill kmemcheck again for the very same reasons.
This patch (of 4):
Remove kmemcheck annotations, and calls to kmemcheck from the kernel.
[alexander.levin@verizon.com: correctly remove kmemcheck call from dma_map_sg_attrs]
Link: http://lkml.kernel.org/r/20171012192151.26531-1-alexander.levin@verizon.com
Link: http://lkml.kernel.org/r/20171007030159.22241-2-alexander.levin@verizon.com
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim Hansen <devtimhansen@gmail.com>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Error injection is sloppy and very ad-hoc. BPF could fill this niche
perfectly with it's kprobe functionality. We could make sure errors are
only triggered in specific call chains that we care about with very
specific situations. Accomplish this with the bpf_override_funciton
helper. This will modify the probe'd callers return value to the
specified value and set the PC to an override function that simply
returns, bypassing the originally probed function. This gives us a nice
clean way to implement systematic error injection for all of our code
paths.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The fact that we don't know which device the program is going
to be used on is quite limiting in current eBPF infrastructure.
We have to reverse or limit the changes which kernel makes to
the loaded bytecode if we want it to be offloaded to a networking
device. We also have to invent new APIs for debugging and
troubleshooting support.
Make it possible to load programs for a specific netdev. This
helps us to bring the debug information closer to the core
eBPF infrastructure (e.g. we will be able to reuse the verifer
log in device JIT). It allows device JITs to perform translation
on the original bytecode.
__bpf_prog_get() when called to get a reference for an attachment
point will now refuse to give it if program has a device assigned.
Following patches will add a version of that function which passes
the expected netdev in. @type argument in __bpf_prog_get() is
renamed to attach_type to make it clearer that it's only set on
attachment.
All calls to ndo_bpf are protected by rtnl, only verifier callbacks
are not. We need a wait queue to make sure netdev doesn't get
destroyed while verifier is still running and calling its driver.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch enables multiple bpf attachments for a
kprobe/uprobe/tracepoint single trace event.
Each trace_event keeps a list of attached perf events.
When an event happens, all attached bpf programs will
be executed based on the order of attachment.
A global bpf_event_mutex lock is introduced to protect
prog_array attaching and detaching. An alternative will
be introduce a mutex lock in every trace_event_call
structure, but it takes a lot of extra memory.
So a global bpf_event_mutex lock is a good compromise.
The bpf prog detachment involves allocation of memory.
If the allocation fails, a dummy do-nothing program
will replace to-be-detached program in-place.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All the trace events defined in include/trace/events/bpf.h are only
used when CONFIG_BPF_SYSCALL is defined. But this file gets included by
include/linux/bpf_trace.h which is included by the networking code with
CREATE_TRACE_POINTS defined.
If a trace event is created but not used it still has data structures
and functions created for its use, even though nothing is using them.
To not waste space, do not define the BPF trace events in bpf.h unless
CONFIG_BPF_SYSCALL is defined.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch makes the bpf_prog's name available
in kallsyms.
The new format is bpf_prog_tag[_name].
Sample kallsyms from running selftests/bpf/test_progs:
[root@arch-fb-vm1 ~]# egrep ' bpf_prog_[0-9a-fA-F]{16}' /proc/kallsyms
ffffffffa0048000 t bpf_prog_dabf0207d1992486_test_obj_id
ffffffffa0038000 t bpf_prog_a04f5eef06a7f555__123456789ABCDE
ffffffffa0050000 t bpf_prog_a04f5eef06a7f555
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
introduce BPF_PROG_QUERY command to retrieve a set of either
attached programs to given cgroup or a set of effective programs
that will execute for events within a cgroup
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
for cgroup bits
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
introduce BPF_F_ALLOW_MULTI flag that can be used to attach multiple
bpf programs to a cgroup.
The difference between three possible flags for BPF_PROG_ATTACH command:
- NONE(default): No further bpf programs allowed in the subtree.
- BPF_F_ALLOW_OVERRIDE: If a sub-cgroup installs some bpf program,
the program in this cgroup yields to sub-cgroup program.
- BPF_F_ALLOW_MULTI: If a sub-cgroup installs some bpf program,
that cgroup program gets run in addition to the program in this cgroup.
NONE and BPF_F_ALLOW_OVERRIDE existed before. This patch doesn't
change their behavior. It only clarifies the semantics in relation
to new flag.
Only one program is allowed to be attached to a cgroup with
NONE or BPF_F_ALLOW_OVERRIDE flag.
Multiple programs are allowed to be attached to a cgroup with
BPF_F_ALLOW_MULTI flag. They are executed in FIFO order
(those that were attached first, run first)
The programs of sub-cgroup are executed first, then programs of
this cgroup and then programs of parent cgroup.
All eligible programs are executed regardless of return code from
earlier programs.
To allow efficient execution of multiple programs attached to a cgroup
and to avoid penalizing cgroups without any programs attached
introduce 'struct bpf_prog_array' which is RCU protected array
of pointers to bpf programs.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
for cgroup bits
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
- bpf prog_array just like all other types of bpf array accepts 32-bit index.
Clarify that in the comment.
- fix x64 JIT of bpf_tail_call which was incorrectly loading 8 instead of 4 bytes
- tighten corresponding check in the interpreter to stay consistent
The JIT bug can be triggered after introduction of BPF_F_NUMA_NODE flag
in commit 96eabe7a40 in 4.14. Before that the map_flags would stay zero and
though JIT code is wrong it will check bounds correctly.
Hence two fixes tags. All other JITs don't have this problem.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Fixes: 96eabe7a40 ("bpf: Allow selecting numa node during map creation")
Fixes: b52f00e6a7 ("x86: bpf_jit: implement bpf_tail_call() helper")
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Resolve issues with !CONFIG_BPF_SYSCALL and !STREAM_PARSER
net/core/filter.c: In function ‘do_sk_redirect_map’:
net/core/filter.c:1881:3: error: implicit declaration of function ‘__sock_map_lookup_elem’ [-Werror=implicit-function-declaration]
sk = __sock_map_lookup_elem(ri->map, ri->ifindex);
^
net/core/filter.c:1881:6: warning: assignment makes pointer from integer without a cast [enabled by default]
sk = __sock_map_lookup_elem(ri->map, ri->ifindex);
Fixes: 174a79ff95 ("bpf: sockmap with sk redirect support")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, eBPF only understands BPF_JGT (>), BPF_JGE (>=),
BPF_JSGT (s>), BPF_JSGE (s>=) instructions, this means that
particularly *JLT/*JLE counterparts involving immediates need
to be rewritten from e.g. X < [IMM] by swapping arguments into
[IMM] > X, meaning the immediate first is required to be loaded
into a register Y := [IMM], such that then we can compare with
Y > X. Note that the destination operand is always required to
be a register.
This has the downside of having unnecessarily increased register
pressure, meaning complex program would need to spill other
registers temporarily to stack in order to obtain an unused
register for the [IMM]. Loading to registers will thus also
affect state pruning since we need to account for that register
use and potentially those registers that had to be spilled/filled
again. As a consequence slightly more stack space might have
been used due to spilling, and BPF programs are a bit longer
due to extra code involving the register load and potentially
required spill/fills.
Thus, add BPF_JLT (<), BPF_JLE (<=), BPF_JSLT (s<), BPF_JSLE (s<=)
counterparts to the eBPF instruction set. Modifying LLVM to
remove the NegateCC() workaround in a PoC patch at [1] and
allowing it to also emit the new instructions resulted in
cilium's BPF programs that are injected into the fast-path to
have a reduced program length in the range of 2-3% (e.g.
accumulated main and tail call sections from one of the object
file reduced from 4864 to 4729 insns), reduced complexity in
the range of 10-30% (e.g. accumulated sections reduced in one
of the cases from 116432 to 88428 insns), and reduced stack
usage in the range of 1-5% (e.g. accumulated sections from one
of the object files reduced from 824 to 784b).
The modification for LLVM will be incorporated in a backwards
compatible way. Plan is for LLVM to have i) a target specific
option to offer a possibility to explicitly enable the extension
by the user (as we have with -m target specific extensions today
for various CPU insns), and ii) have the kernel checked for
presence of the extensions and enable them transparently when
the user is selecting more aggressive options such as -march=native
in a bpf target context. (Other frontends generating BPF byte
code, e.g. ply can probe the kernel directly for its code
generation.)
[1] https://github.com/borkmann/llvm/tree/bpf-insns
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The index is off-by-one when fp->aux->stack_depth
has already been rounded up to 32. In particular,
if stack_depth is 512, the index will be 16.
The fix is to round_up and then takes -1 instead of round_down.
[ 22.318680] ==================================================================
[ 22.319745] BUG: KASAN: global-out-of-bounds in bpf_prog_select_runtime+0x48a/0x670
[ 22.320737] Read of size 8 at addr ffffffff82aadae0 by task sockex3/1946
[ 22.321646]
[ 22.321858] CPU: 1 PID: 1946 Comm: sockex3 Tainted: G W 4.12.0-rc6-01680-g2ee87db3a287 #22
[ 22.323061] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-1.el7.centos 04/01/2014
[ 22.324260] Call Trace:
[ 22.324612] dump_stack+0x67/0x99
[ 22.325081] print_address_description+0x1e8/0x290
[ 22.325734] ? bpf_prog_select_runtime+0x48a/0x670
[ 22.326360] kasan_report+0x265/0x350
[ 22.326860] __asan_report_load8_noabort+0x19/0x20
[ 22.327484] bpf_prog_select_runtime+0x48a/0x670
[ 22.328109] bpf_prog_load+0x626/0xd40
[ 22.328637] ? __bpf_prog_charge+0xc0/0xc0
[ 22.329222] ? check_nnp_nosuid.isra.61+0x100/0x100
[ 22.329890] ? __might_fault+0xf6/0x1b0
[ 22.330446] ? lock_acquire+0x360/0x360
[ 22.331013] SyS_bpf+0x67c/0x24d0
[ 22.331491] ? trace_hardirqs_on+0xd/0x10
[ 22.332049] ? __getnstimeofday64+0xaf/0x1c0
[ 22.332635] ? bpf_prog_get+0x20/0x20
[ 22.333135] ? __audit_syscall_entry+0x300/0x600
[ 22.333770] ? syscall_trace_enter+0x540/0xdd0
[ 22.334339] ? exit_to_usermode_loop+0xe0/0xe0
[ 22.334950] ? do_syscall_64+0x48/0x410
[ 22.335446] ? bpf_prog_get+0x20/0x20
[ 22.335954] do_syscall_64+0x181/0x410
[ 22.336454] entry_SYSCALL64_slow_path+0x25/0x25
[ 22.337121] RIP: 0033:0x7f263fe81f19
[ 22.337618] RSP: 002b:00007ffd9a3440c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000141
[ 22.338619] RAX: ffffffffffffffda RBX: 0000000000aac5fb RCX: 00007f263fe81f19
[ 22.339600] RDX: 0000000000000030 RSI: 00007ffd9a3440d0 RDI: 0000000000000005
[ 22.340470] RBP: 0000000000a9a1e0 R08: 0000000000a9a1e0 R09: 0000009d00000001
[ 22.341430] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000010000
[ 22.342411] R13: 0000000000a9a023 R14: 0000000000000001 R15: 0000000000000003
[ 22.343369]
[ 22.343593] The buggy address belongs to the variable:
[ 22.344241] interpreters+0x80/0x980
[ 22.344708]
[ 22.344908] Memory state around the buggy address:
[ 22.345556] ffffffff82aad980: 00 00 00 04 fa fa fa fa 04 fa fa fa fa fa fa fa
[ 22.346449] ffffffff82aada00: 00 00 00 00 00 fa fa fa fa fa fa fa 00 00 00 00
[ 22.347361] >ffffffff82aada80: 00 00 00 00 00 00 00 00 00 00 00 00 fa fa fa fa
[ 22.348301] ^
[ 22.349142] ffffffff82aadb00: 00 01 fa fa fa fa fa fa 00 00 00 00 00 00 00 00
[ 22.350058] ffffffff82aadb80: 00 00 07 fa fa fa fa fa 00 00 05 fa fa fa fa fa
[ 22.350984] ==================================================================
Fixes: b870aa901f ("bpf: use different interpreter depending on required stack size")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
16 __bpf_prog_run() interpreters for various stack sizes add .text
but not a lot comparing to run-time stack savings
text data bss dec hex filename
26350 10328 624 37302 91b6 kernel/bpf/core.o.before_split
25777 10328 624 36729 8f79 kernel/bpf/core.o.after_split
26970 10328 624 37922 9422 kernel/bpf/core.o.now
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
free up BPF_JMP | BPF_CALL | BPF_X opcode to be used by actual
indirect call by register and use kernel internal opcode to
mark call instruction into bpf_tail_call() helper.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
__vmalloc* allows users to provide gfp flags for the underlying
allocation. This API is quite popular
$ git grep "=[[:space:]]__vmalloc\|return[[:space:]]*__vmalloc" | wc -l
77
The only problem is that many people are not aware that they really want
to give __GFP_HIGHMEM along with other flags because there is really no
reason to consume precious lowmemory on CONFIG_HIGHMEM systems for pages
which are mapped to the kernel vmalloc space. About half of users don't
use this flag, though. This signals that we make the API unnecessarily
too complex.
This patch simply uses __GFP_HIGHMEM implicitly when allocating pages to
be mapped to the vmalloc space. Current users which add __GFP_HIGHMEM
are simplified and drop the flag.
Link: http://lkml.kernel.org/r/20170307141020.29107-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Cristopher Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Hannes rightfully spotted that the bpf_lock doesn't need to be
irqsave variant. We never perform any such updates where this
would be necessary (neither right now nor in future), therefore
relax this further.
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
It took me quite some time to figure out how this was linked,
so in order to save the next person the effort of finding it
add a comment in __bpf_prog_run() that indicates what exactly
determines that a program can access the ctx == skb.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Long standing issue with JITed programs is that stack traces from
function tracing check whether a given address is kernel code
through {__,}kernel_text_address(), which checks for code in core
kernel, modules and dynamically allocated ftrace trampolines. But
what is still missing is BPF JITed programs (interpreted programs
are not an issue as __bpf_prog_run() will be attributed to them),
thus when a stack trace is triggered, the code walking the stack
won't see any of the JITed ones. The same for address correlation
done from user space via reading /proc/kallsyms. This is read by
tools like perf, but the latter is also useful for permanent live
tracing with eBPF itself in combination with stack maps when other
eBPF types are part of the callchain. See offwaketime example on
dumping stack from a map.
This work tries to tackle that issue by making the addresses and
symbols known to the kernel. The lookup from *kernel_text_address()
is implemented through a latched RB tree that can be read under
RCU in fast-path that is also shared for symbol/size/offset lookup
for a specific given address in kallsyms. The slow-path iteration
through all symbols in the seq file done via RCU list, which holds
a tiny fraction of all exported ksyms, usually below 0.1 percent.
Function symbols are exported as bpf_prog_<tag>, in order to aide
debugging and attribution. This facility is currently enabled for
root-only when bpf_jit_kallsyms is set to 1, and disabled if hardening
is active in any mode. The rationale behind this is that still a lot
of systems ship with world read permissions on kallsyms thus addresses
should not get suddenly exposed for them. If that situation gets
much better in future, we always have the option to change the
default on this. Likewise, unprivileged programs are not allowed
to add entries there either, but that is less of a concern as most
such programs types relevant in this context are for root-only anyway.
If enabled, call graphs and stack traces will then show a correct
attribution; one example is illustrated below, where the trace is
now visible in tooling such as perf script --kallsyms=/proc/kallsyms
and friends.
Before:
7fff8166889d bpf_clone_redirect+0x80007f0020ed (/lib/modules/4.9.0-rc8+/build/vmlinux)
f5d80 __sendmsg_nocancel+0xffff006451f1a007 (/usr/lib64/libc-2.18.so)
After:
7fff816688b7 bpf_clone_redirect+0x80007f002107 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fffa0575728 bpf_prog_33c45a467c9e061a+0x8000600020fb (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fffa07ef1fc cls_bpf_classify+0x8000600020dc (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff81678b68 tc_classify+0x80007f002078 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff8164d40b __netif_receive_skb_core+0x80007f0025fb (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff8164d718 __netif_receive_skb+0x80007f002018 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff8164e565 process_backlog+0x80007f002095 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff8164dc71 net_rx_action+0x80007f002231 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff81767461 __softirqentry_text_start+0x80007f0020d1 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff817658ac do_softirq_own_stack+0x80007f00201c (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff810a2c20 do_softirq+0x80007f002050 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff810a2cb5 __local_bh_enable_ip+0x80007f002085 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff8168d452 ip_finish_output2+0x80007f002152 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff8168ea3d ip_finish_output+0x80007f00217d (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff8168f2af ip_output+0x80007f00203f (/lib/modules/4.9.0-rc8+/build/vmlinux)
[...]
7fff81005854 do_syscall_64+0x80007f002054 (/lib/modules/4.9.0-rc8+/build/vmlinux)
7fff817649eb return_from_SYSCALL_64+0x80007f002000 (/lib/modules/4.9.0-rc8+/build/vmlinux)
f5d80 __sendmsg_nocancel+0xffff01c484812007 (/usr/lib64/libc-2.18.so)
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove the dummy bpf_jit_compile() stubs for eBPF JITs and make
that a single __weak function in the core that can be overridden
similarly to the eBPF one. Also remove stale pr_err() mentions
of bpf_jit_compile.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This work adds a number of tracepoints to paths that are either
considered slow-path or exception-like states, where monitoring or
inspecting them would be desirable.
For bpf(2) syscall, tracepoints have been placed for main commands
when they succeed. In XDP case, tracepoint is for exceptions, that
is, f.e. on abnormal BPF program exit such as unknown or XDP_ABORTED
return code, or when error occurs during XDP_TX action and the packet
could not be forwarded.
Both have been split into separate event headers, and can be further
extended. Worst case, if they unexpectedly should get into our way in
future, they can also removed [1]. Of course, these tracepoints (like
any other) can be analyzed by eBPF itself, etc. Example output:
# ./perf record -a -e bpf:* sleep 10
# ./perf script
sock_example 6197 [005] 283.980322: bpf:bpf_map_create: map type=ARRAY ufd=4 key=4 val=8 max=256 flags=0
sock_example 6197 [005] 283.980721: bpf:bpf_prog_load: prog=a5ea8fa30ea6849c type=SOCKET_FILTER ufd=5
sock_example 6197 [005] 283.988423: bpf:bpf_prog_get_type: prog=a5ea8fa30ea6849c type=SOCKET_FILTER
sock_example 6197 [005] 283.988443: bpf:bpf_map_lookup_elem: map type=ARRAY ufd=4 key=[06 00 00 00] val=[00 00 00 00 00 00 00 00]
[...]
sock_example 6197 [005] 288.990868: bpf:bpf_map_lookup_elem: map type=ARRAY ufd=4 key=[01 00 00 00] val=[14 00 00 00 00 00 00 00]
swapper 0 [005] 289.338243: bpf:bpf_prog_put_rcu: prog=a5ea8fa30ea6849c type=SOCKET_FILTER
[1] https://lwn.net/Articles/705270/
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 7bd509e311 ("bpf: add prog_digest and expose it via
fdinfo/netlink") was recently discussed, partially due to
admittedly suboptimal name of "prog_digest" in combination
with sha1 hash usage, thus inevitably and rightfully concerns
about its security in terms of collision resistance were
raised with regards to use-cases.
The intended use cases are for debugging resp. introspection
only for providing a stable "tag" over the instruction sequence
that both kernel and user space can calculate independently.
It's not usable at all for making a security relevant decision.
So collisions where two different instruction sequences generate
the same tag can happen, but ideally at a rather low rate. The
"tag" will be dumped in hex and is short enough to introspect
in tracepoints or kallsyms output along with other data such
as stack trace, etc. Thus, this patch performs a rename into
prog_tag and truncates the tag to a short output (64 bits) to
make it obvious it's not collision-free.
Should in future a hash or facility be needed with a security
relevant focus, then we can think about requirements, constraints,
etc that would fit to that situation. For now, rework the exposed
parts for the current use cases as long as nothing has been
released yet. Tested on x86_64 and s390x.
Fixes: 7bd509e311 ("bpf: add prog_digest and expose it via fdinfo/netlink")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit aaac3ba95e ("bpf: charge user for creation of BPF maps and
programs") made a wrong assumption of charging against prog->pages.
Unlike map->pages, prog->pages are still subject to change when we
need to expand the program through bpf_prog_realloc().
This can for example happen during verification stage when we need to
expand and rewrite parts of the program. Should the required space
cross a page boundary, then prog->pages is not the same anymore as
its original value that we used to bpf_prog_charge_memlock() on. Thus,
we'll hit a wrap-around during bpf_prog_uncharge_memlock() when prog
is freed eventually. I noticed this that despite having unlimited
memlock, programs suddenly refused to load with EPERM error due to
insufficient memlock.
There are two ways to fix this issue. One would be to add a cached
variable to struct bpf_prog that takes a snapshot of prog->pages at the
time of charging. The other approach is to also account for resizes. I
chose to go with the latter for a couple of reasons: i) We want accounting
rather to be more accurate instead of further fooling limits, ii) adding
yet another page counter on struct bpf_prog would also be a waste just
for this purpose. We also do want to charge as early as possible to
avoid going into the verifier just to find out later on that we crossed
limits. The only place that needs to be fixed is bpf_prog_realloc(),
since only here we expand the program, so we try to account for the
needed delta and should we fail, call-sites check for outcome anyway.
On cBPF to eBPF migrations, we don't grab a reference to the user as
they are charged differently. With that in place, my test case worked
fine.
Fixes: aaac3ba95e ("bpf: charge user for creation of BPF maps and programs")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Geert rightfully complained that 7bd509e311 ("bpf: add prog_digest
and expose it via fdinfo/netlink") added a too large allocation of
variable 'raw' from bss section, and should instead be done dynamically:
# ./scripts/bloat-o-meter kernel/bpf/core.o.1 kernel/bpf/core.o.2
add/remove: 3/0 grow/shrink: 0/0 up/down: 33291/0 (33291)
function old new delta
raw - 32832 +32832
[...]
Since this is only relevant during program creation path, which can be
considered slow-path anyway, lets allocate that dynamically and be not
implicitly dependent on verifier mutex. Move bpf_prog_calc_digest() at
the beginning of replace_map_fd_with_map_ptr() and also error handling
stays straight forward.
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch allows XDP prog to extend/remove the packet
data at the head (like adding or removing header). It is
done by adding a new XDP helper bpf_xdp_adjust_head().
It also renames bpf_helper_changes_skb_data() to
bpf_helper_changes_pkt_data() to better reflect
that XDP prog does not work on skb.
This patch adds one "xdp_adjust_head" bit to bpf_prog for the
XDP-capable driver to check if the XDP prog requires
bpf_xdp_adjust_head() support. The driver can then decide
to error out during XDP_SETUP_PROG.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When loading a BPF program via bpf(2), calculate the digest over
the program's instruction stream and store it in struct bpf_prog's
digest member. This is done at a point in time before any instructions
are rewritten by the verifier. Any unstable map file descriptor
number part of the imm field will be zeroed for the hash.
fdinfo example output for progs:
# cat /proc/1590/fdinfo/5
pos: 0
flags: 02000002
mnt_id: 11
prog_type: 1
prog_jited: 1
prog_digest: b27e8b06da22707513aa97363dfb11c7c3675d28
memlock: 4096
When programs are pinned and retrieved by an ELF loader, the loader
can check the program's digest through fdinfo and compare it against
one that was generated over the ELF file's program section to see
if the program needs to be reloaded. Furthermore, this can also be
exposed through other means such as netlink in case of a tc cls/act
dump (or xdp in future), but also through tracepoints or other
facilities to identify the program. Other than that, the digest can
also serve as a base name for the work in progress kallsyms support
of programs. The digest doesn't depend/select the crypto layer, since
we need to keep dependencies to a minimum. iproute2 will get support
for this facility.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use case is mainly for soreuseport to select sockets for the local
numa node, but since generic, lets also add this for other networking
and tracing program types.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
put_cpu_var takes the percpu data, not the data returned from
get_cpu_var.
This doesn't change the behavior.
Cc: Tejun Heo <tj@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stanislav Fomichev