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43473 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Yonghong Song
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9beda16c25 |
bpf: Avoid unnecessary extra percpu memory allocation
Currently, for percpu memory allocation, say if the user requests allocation size to be 32 bytes, the actually calculated size will be 40 bytes and it further rounds to 64 bytes, and eventually 64 bytes are allocated, wasting 32-byte memory. Change bpf_mem_alloc() to calculate the cache index based on the user-provided allocation size so unnecessary extra memory can be avoided. Suggested-by: Hou Tao <houtao1@huawei.com> Acked-by: Hou Tao <houtao1@huawei.com> Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20231222031734.1288400-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Andrei Matei
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8a021e7fa1 |
bpf: Simplify checking size of helper accesses
This patch simplifies the verification of size arguments associated to pointer arguments to helpers and kfuncs. Many helpers take a pointer argument followed by the size of the memory access performed to be performed through that pointer. Before this patch, the handling of the size argument in check_mem_size_reg() was confusing and wasteful: if the size register's lower bound was 0, then the verification was done twice: once considering the size of the access to be the lower-bound of the respective argument, and once considering the upper bound (even if the two are the same). The upper bound checking is a super-set of the lower-bound checking(*), except: the only point of the lower-bound check is to handle the case where zero-sized-accesses are explicitly not allowed and the lower-bound is zero. This static condition is now checked explicitly, replacing a much more complex, expensive and confusing verification call to check_helper_mem_access(). Error messages change in this patch. Before, messages about illegal zero-size accesses depended on the type of the pointer and on other conditions, and sometimes the message was plain wrong: in some tests that changed you'll see that the old message was something like "R1 min value is outside of the allowed memory range", where R1 is the pointer register; the error was wrongly claiming that the pointer was bad instead of the size being bad. Other times the information that the size came for a register with a possible range of values was wrong, and the error presented the size as a fixed zero. Now the errors refer to the right register. However, the old error messages did contain useful information about the pointer register which is now lost; recovering this information was deemed not important enough. (*) Besides standing to reason that the checks for a bigger size access are a super-set of the checks for a smaller size access, I have also mechanically verified this by reading the code for all types of pointers. I could convince myself that it's true for all but PTR_TO_BTF_ID (check_ptr_to_btf_access). There, simply looking line-by-line does not immediately prove what we want. If anyone has any qualms, let me know. Signed-off-by: Andrei Matei <andreimatei1@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20231221232225.568730-2-andreimatei1@gmail.com |
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David S. Miller
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240436c06c |
bpf-next-for-netdev
-----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTFp0I1jqZrAX+hPRXbK58LschIgwUCZYVEqQAKCRDbK58LschI gzH6AP9hVXLpHFTWMT0+2GK2lx69VX8zW1C0SmN7WHaxUbPN9QEAwzGnELfKk00P 0IKRHSl5abhVMX7JOM3sSOhCILeKjQg= =wRLJ -----END PGP SIGNATURE----- Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next Daniel Borkmann says: ==================== bpf-next-for-netdev The following pull-request contains BPF updates for your *net-next* tree. We've added 22 non-merge commits during the last 3 day(s) which contain a total of 23 files changed, 652 insertions(+), 431 deletions(-). The main changes are: 1) Add verifier support for annotating user's global BPF subprogram arguments with few commonly requested annotations for a better developer experience, from Andrii Nakryiko. These tags are: - Ability to annotate a special PTR_TO_CTX argument - Ability to annotate a generic PTR_TO_MEM as non-NULL 2) Support BPF verifier tracking of BPF_JNE which helps cases when the compiler transforms (unsigned) "a > 0" into "if a == 0 goto xxx" and the like, from Menglong Dong. 3) Fix a warning in bpf_mem_cache's check_obj_size() as reported by LKP, from Hou Tao. 4) Re-support uid/gid options when mounting bpffs which had to be reverted with the prior token series revert to avoid conflicts, from Daniel Borkmann. 5) Fix a libbpf NULL pointer dereference in bpf_object__collect_prog_relos() found from fuzzing the library with malformed ELF files, from Mingyi Zhang. 6) Skip DWARF sections in libbpf's linker sanity check given compiler options to generate compressed debug sections can trigger a rejection due to misalignment, from Alyssa Ross. 7) Fix an unnecessary use of the comma operator in BPF verifier, from Simon Horman. 8) Fix format specifier for unsigned long values in cpustat sample, from Colin Ian King. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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Simon Horman
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5abde62465 |
bpf: Avoid unnecessary use of comma operator in verifier
Although it does not seem to have any untoward side-effects, the use of ';' to separate to assignments seems more appropriate than ','. Flagged by clang-17 -Wcomma No functional change intended. Compile tested only. Signed-off-by: Simon Horman <horms@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Dave Marchevsky <davemarchevsky@fb.com> Link: https://lore.kernel.org/bpf/20231221-bpf-verifier-comma-v1-1-cde2530912e9@kernel.org |
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Paolo Abeni
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56794e5358 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR.
Adjacent changes:
drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
23c93c3b6275 ("bnxt_en: do not map packet buffers twice")
6d1add95536b ("bnxt_en: Modify TX ring indexing logic.")
tools/testing/selftests/net/Makefile
2258b666482d ("selftests: add vlan hw filter tests")
a0bc96c0cd6e ("selftests: net: verify fq per-band packet limit")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Daniel Borkmann
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b08c8fc041 |
bpf: Re-support uid and gid when mounting bpffs
For a clean, conflict-free revert of the token-related patches in commit
d17aff807f84 ("Revert BPF token-related functionality"), the bpf fs commit
750e785796bb ("bpf: Support uid and gid when mounting bpffs") was undone
temporarily as well.
This patch manually re-adds the functionality from the original one back
in 750e785796bb, no other functional changes intended.
Testing:
# mount -t bpf -o uid=65534,gid=65534 bpffs ./foo
# ls -la . | grep foo
drwxrwxrwt 2 nobody nogroup 0 Dec 20 13:16 foo
# mount -t bpf
bpffs on /root/foo type bpf (rw,relatime,uid=65534,gid=65534)
Also, passing invalid arguments for uid/gid are properly rejected as expected.
Fixes: d17aff807f84 ("Revert BPF token-related functionality")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Cc: Jie Jiang <jiejiang@chromium.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/bpf/20231220133805.20953-1-daniel@iogearbox.net
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Linus Torvalds
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a4aebe9365 |
posix-timers: Get rid of [COMPAT_]SYS_NI() uses
Only the posix timer system calls use this (when the posix timer support is disabled, which does not actually happen in any normal case), because they had debug code to print out a warning about missing system calls. Get rid of that special case, and just use the standard COND_SYSCALL interface that creates weak system call stubs that return -ENOSYS for when the system call does not exist. This fixes a kCFI issue with the SYS_NI() hackery: CFI failure at int80_emulation+0x67/0xb0 (target: sys_ni_posix_timers+0x0/0x70; expected type: 0xb02b34d9) WARNING: CPU: 0 PID: 48 at int80_emulation+0x67/0xb0 Reported-by: kernel test robot <oliver.sang@intel.com> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Hou Tao
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7ac5c53e00 |
bpf: Use c->unit_size to select target cache during free
At present, bpf memory allocator uses check_obj_size() to ensure that
ksize() of allocated pointer is equal with the unit_size of used
bpf_mem_cache. Its purpose is to prevent bpf_mem_free() from selecting
a bpf_mem_cache which has different unit_size compared with the
bpf_mem_cache used for allocation. But as reported by lkp, the return
value of ksize() or kmalloc_size_roundup() may change due to slab merge
and it will lead to the warning report in check_obj_size().
The reported warning happened as follows:
(1) in bpf_mem_cache_adjust_size(), kmalloc_size_roundup(96) returns the
object_size of kmalloc-96 instead of kmalloc-cg-96. The object_size of
kmalloc-96 is 96, so size_index for 96 is not adjusted accordingly.
(2) the object_size of kmalloc-cg-96 is adjust from 96 to 128 due to
slab merge in __kmem_cache_alias(). For SLAB, SLAB_HWCACHE_ALIGN is
enabled by default for kmalloc slab, so align is 64 and size is 128 for
kmalloc-cg-96. SLUB has a similar merge logic, but its object_size will
not be changed, because its align is 8 under x86-64.
(3) when unit_alloc() does kmalloc_node(96, __GFP_ACCOUNT, node),
ksize() returns 128 instead of 96 for the returned pointer.
(4) the warning in check_obj_size() is triggered.
Considering the slab merge can happen in anytime (e.g, a slab created in
a new module), the following case is also possible: during the
initialization of bpf_global_ma, there is no slab merge and ksize() for
a 96-bytes object returns 96. But after that a new slab created by a
kernel module is merged to kmalloc-cg-96 and the object_size of
kmalloc-cg-96 is adjust from 96 to 128 (which is possible for x86-64 +
CONFIG_SLAB, because its alignment requirement is 64 for 96-bytes slab).
So soon or later, when bpf_global_ma frees a 96-byte-sized pointer
which is allocated from bpf_mem_cache with unit_size=96, bpf_mem_free()
will free the pointer through a bpf_mem_cache in which unit_size is 128,
because the return value of ksize() changes. The warning for the
mismatch will be triggered again.
A feasible fix is introducing similar APIs compared with ksize() and
kmalloc_size_roundup() to return the actually-allocated size instead of
size which may change due to slab merge, but it will introduce
unnecessary dependency on the implementation details of mm subsystem.
As for now the pointer of bpf_mem_cache is saved in the 8-bytes area
(or 4-bytes under 32-bit host) above the returned pointer, using
unit_size in the saved bpf_mem_cache to select the target cache instead
of inferring the size from the pointer itself. Beside no extra
dependency on mm subsystem, the performance for bpf_mem_free_rcu() is
also improved as shown below.
Before applying the patch, the performances of bpf_mem_alloc() and
bpf_mem_free_rcu() on 8-CPUs VM with one producer are as follows:
kmalloc : alloc 11.69 ± 0.28M/s free 29.58 ± 0.93M/s
percpu : alloc 14.11 ± 0.52M/s free 14.29 ± 0.99M/s
After apply the patch, the performance for bpf_mem_free_rcu() increases
9% and 146% for kmalloc memory and per-cpu memory respectively:
kmalloc: alloc 11.01 ± 0.03M/s free 32.42 ± 0.48M/s
percpu: alloc 12.84 ± 0.12M/s free 35.24 ± 0.23M/s
After the fixes, there is no need to adjust size_index to fix the
mismatch between allocation and free, so remove it as well. Also return
NULL instead of ZERO_SIZE_PTR for zero-sized alloc in bpf_mem_alloc(),
because there is no bpf_mem_cache pointer saved above ZERO_SIZE_PTR.
Fixes: 9077fc228f09 ("bpf: Use kmalloc_size_roundup() to adjust size_index")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/bpf/202310302113.9f8fe705-oliver.sang@intel.com
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231216131052.27621-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Andrii Nakryiko
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a64bfe6186 |
bpf: add support for passing dynptr pointer to global subprog
Add ability to pass a pointer to dynptr into global functions. This allows to have global subprogs that accept and work with generic dynptrs that are created by caller. Dynptr argument is detected based on the name of a struct type, if it's "bpf_dynptr", it's assumed to be a proper dynptr pointer. Both actual struct and forward struct declaration types are supported. This is conceptually exactly the same semantics as bpf_user_ringbuf_drain()'s use of dynptr to pass a variable-sized pointer to ringbuf record. So we heavily rely on CONST_PTR_TO_DYNPTR bits of already existing logic in the verifier. During global subprog validation, we mark such CONST_PTR_TO_DYNPTR as having LOCAL type, as that's the most unassuming type of dynptr and it doesn't have any special helpers that can try to free or acquire extra references (unlike skb, xdp, or ringbuf dynptr). So that seems like a safe "choice" to make from correctness standpoint. It's still possible to pass any type of dynptr to such subprog, though, because generic dynptr helpers, like getting data/slice pointers, read/write memory copying routines, dynptr adjustment and getter routines all work correctly with any type of dynptr. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-8-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Andrii Nakryiko
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94e1c70a34 |
bpf: support 'arg:xxx' btf_decl_tag-based hints for global subprog args
Add support for annotating global BPF subprog arguments to provide more
information about expected semantics of the argument. Currently,
verifier relies purely on argument's BTF type information, and supports
three general use cases: scalar, pointer-to-context, and
pointer-to-fixed-size-memory.
Scalar and pointer-to-fixed-mem work well in practice and are quite
natural to use. But pointer-to-context is a bit problematic, as typical
BPF users don't realize that they need to use a special type name to
signal to verifier that argument is not just some pointer, but actually
a PTR_TO_CTX. Further, even if users do know which type to use, it is
limiting in situations where the same BPF program logic is used across
few different program types. Common case is kprobes, tracepoints, and
perf_event programs having a helper to send some data over BPF perf
buffer. bpf_perf_event_output() requires `ctx` argument, and so it's
quite cumbersome to share such global subprog across few BPF programs of
different types, necessitating extra static subprog that is context
type-agnostic.
Long story short, there is a need to go beyond types and allow users to
add hints to global subprog arguments to define expectations.
This patch adds such support for two initial special tags:
- pointer to context;
- non-null qualifier for generic pointer arguments.
All of the above came up in practice already and seem generally useful
additions. Non-null qualifier is an often requested feature, which
currently has to be worked around by having unnecessary NULL checks
inside subprogs even if we know that arguments are never NULL. Pointer
to context was discussed earlier.
As for implementation, we utilize btf_decl_tag attribute and set up an
"arg:xxx" convention to specify argument hint. As such:
- btf_decl_tag("arg:ctx") is a PTR_TO_CTX hint;
- btf_decl_tag("arg:nonnull") marks pointer argument as not allowed to
be NULL, making NULL check inside global subprog unnecessary.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Andrii Nakryiko
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f18c3d88de |
bpf: reuse subprog argument parsing logic for subprog call checks
Remove duplicated BTF parsing logic when it comes to subprog call check. Instead, use (potentially cached) results of btf_prepare_func_args() to abstract away expectations of each subprog argument in generic terms (e.g., "this is pointer to context", or "this is a pointer to memory of size X"), and then use those simple high-level argument type expectations to validate actual register states to check if they match expectations. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Andrii Nakryiko
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c5a7244759 |
bpf: move subprog call logic back to verifier.c
Subprog call logic in btf_check_subprog_call() currently has both a lot of BTF parsing logic (which is, presumably, what justified putting it into btf.c), but also a bunch of register state checks, some of each utilize deep verifier logic helpers, necessarily exported from verifier.c: check_ptr_off_reg(), check_func_arg_reg_off(), and check_mem_reg(). Going forward, btf_check_subprog_call() will have a minimum of BTF-related logic, but will get more internal verifier logic related to register state manipulation. So move it into verifier.c to minimize amount of verifier-specific logic exposed to btf.c. We do this move before refactoring btf_check_func_arg_match() to preserve as much history post-refactoring as possible. No functional changes. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Andrii Nakryiko
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e26080d0da |
bpf: prepare btf_prepare_func_args() for handling static subprogs
Generalize btf_prepare_func_args() to support both global and static subprogs. We are going to utilize this property in the next patch, reusing btf_prepare_func_args() for subprog call logic instead of reparsing BTF information in a completely separate implementation. btf_prepare_func_args() now detects whether subprog is global or static makes slight logic adjustments for static func cases, like not failing fatally (-EFAULT) for conditions that are allowable for static subprogs. Somewhat subtle (but major!) difference is the handling of pointer arguments. Both global and static functions need to handle special context arguments (which are pointers to predefined type names), but static subprogs give up on any other pointers, falling back to marking subprog as "unreliable", disabling the use of BTF type information altogether. For global functions, though, we are assuming that such pointers to unrecognized types are just pointers to fixed-sized memory region (or error out if size cannot be established, like for `void *` pointers). This patch accommodates these small differences and sets up a stage for refactoring in the next patch, eliminating a separate BTF-based parsing logic in btf_check_func_arg_match(). Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Andrii Nakryiko
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5eccd2db42 |
bpf: reuse btf_prepare_func_args() check for main program BTF validation
Instead of btf_check_subprog_arg_match(), use btf_prepare_func_args() logic to validate "trustworthiness" of main BPF program's BTF information, if it is present. We ignored results of original BTF check anyway, often times producing confusing and ominously-sounding "reg type unsupported for arg#0 function" message, which has no apparent effect on program correctness and verification process. All the -EFAULT returning sanity checks are already performed in check_btf_info_early(), so there is zero reason to have this duplication of logic between btf_check_subprog_call() and btf_check_subprog_arg_match(). Dropping btf_check_subprog_arg_match() simplifies btf_check_func_arg_match() further removing `bool processing_call` flag. One subtle bit that was done by btf_check_subprog_arg_match() was potentially marking main program's BTF as unreliable. We do this explicitly now with a dedicated simple check, preserving the original behavior, but now based on well factored btf_prepare_func_args() logic. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Andrii Nakryiko
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4ba1d0f234 |
bpf: abstract away global subprog arg preparation logic from reg state setup
btf_prepare_func_args() is used to understand expectations and restrictions on global subprog arguments. But current implementation is hard to extend, as it intermixes BTF-based func prototype parsing and interpretation logic with setting up register state at subprog entry. Worse still, those registers are not completely set up inside btf_prepare_func_args(), requiring some more logic later in do_check_common(). Like calling mark_reg_unknown() and similar initialization operations. This intermixing of BTF interpretation and register state setup is problematic. First, it causes duplication of BTF parsing logic for global subprog verification (to set up initial state of global subprog) and global subprog call sites analysis (when we need to check that whatever is being passed into global subprog matches expectations), performed in btf_check_subprog_call(). Given we want to extend global func argument with tags later, this duplication is problematic. So refactor btf_prepare_func_args() to do only BTF-based func proto and args parsing, returning high-level argument "expectations" only, with no regard to specifics of register state. I.e., if it's a context argument, instead of setting register state to PTR_TO_CTX, we return ARG_PTR_TO_CTX enum for that argument as "an argument specification" for further processing inside do_check_common(). Similarly for SCALAR arguments, PTR_TO_MEM, etc. This allows to reuse btf_prepare_func_args() in following patches at global subprog call site analysis time. It also keeps register setup code consistently in one place, do_check_common(). Besides all this, we cache this argument specs information inside env->subprog_info, eliminating the need to redo these potentially expensive BTF traversals, especially if BPF program's BTF is big and/or there are lots of global subprog calls. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Menglong Dong
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d028f87517 |
bpf: make the verifier tracks the "not equal" for regs
We can derive some new information for BPF_JNE in regs_refine_cond_op().
Take following code for example:
/* The type of "a" is u32 */
if (a > 0 && a < 100) {
/* the range of the register for a is [0, 99], not [1, 99],
* and will cause the following error:
*
* invalid zero-sized read
*
* as a can be 0.
*/
bpf_skb_store_bytes(skb, xx, xx, a, 0);
}
In the code above, "a > 0" will be compiled to "jmp xxx if a == 0". In the
TRUE branch, the dst_reg will be marked as known to 0. However, in the
fallthrough(FALSE) branch, the dst_reg will not be handled, which makes
the [min, max] for a is [0, 99], not [1, 99].
For BPF_JNE, we can reduce the range of the dst reg if the src reg is a
const and is exactly the edge of the dst reg.
Signed-off-by: Menglong Dong <menglong8.dong@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231219134800.1550388-2-menglong8.dong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Linus Torvalds
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55cb5f4368 |
tracing fix for 6.7-rc6
While working on the ring buffer, I found one more bug with the timestamp
code, and the fix for this removed the need for the final 64-bit cmpxchg!
The ring buffer events hold a "delta" from the previous event. If it is
determined that the delta can not be calculated, it falls back to adding an
absolute timestamp value. The way to know if the delta can be used is via
two stored timestamps in the per-cpu buffer meta data:
before_stamp and write_stamp
The before_stamp is written by every event before it tries to allocate its
space on the ring buffer. The write_stamp is written after it allocates its
space and knows that nothing came in after it read the previous
before_stamp and write_stamp and the two matched.
A previous fix dd9394257078 ("ring-buffer: Do not try to put back
write_stamp") removed putting back the write_stamp to match the
before_stamp so that the next event could use the delta, but races were
found where the two would match, but not be for of the previous event.
It was determined to allow the event reservation to not have a valid
write_stamp when it is finished, and this fixed a lot of races.
The last use of the 64-bit timestamp cmpxchg depended on the write_stamp
being valid after an interruption. But this is no longer the case, as if an
event is interrupted by a softirq that writes an event, and that event gets
interrupted by a hardirq or NMI and that writes an event, then the softirq
could finish its reservation without a valid write_stamp.
In the slow path of the event reservation, a delta can still be used if the
write_stamp is valid. Instead of using a cmpxchg against the write stamp,
the before_stamp needs to be read again to validate the write_stamp. The
cmpxchg is not needed.
This updates the slowpath to validate the write_stamp by comparing it to
the before_stamp and removes all rb_time_cmpxchg() as there are no more
users of that function.
The removal of the 32-bit updates of rb_time_t will be done in the next
merge window.
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Merge tag 'trace-v6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fix from Steven Rostedt:
"While working on the ring buffer, I found one more bug with the
timestamp code, and the fix for this removed the need for the final
64-bit cmpxchg!
The ring buffer events hold a "delta" from the previous event. If it
is determined that the delta can not be calculated, it falls back to
adding an absolute timestamp value. The way to know if the delta can
be used is via two stored timestamps in the per-cpu buffer meta data:
before_stamp and write_stamp
The before_stamp is written by every event before it tries to allocate
its space on the ring buffer. The write_stamp is written after it
allocates its space and knows that nothing came in after it read the
previous before_stamp and write_stamp and the two matched.
A previous fix dd9394257078 ("ring-buffer: Do not try to put back
write_stamp") removed putting back the write_stamp to match the
before_stamp so that the next event could use the delta, but races
were found where the two would match, but not be for of the previous
event.
It was determined to allow the event reservation to not have a valid
write_stamp when it is finished, and this fixed a lot of races.
The last use of the 64-bit timestamp cmpxchg depended on the
write_stamp being valid after an interruption. But this is no longer
the case, as if an event is interrupted by a softirq that writes an
event, and that event gets interrupted by a hardirq or NMI and that
writes an event, then the softirq could finish its reservation without
a valid write_stamp.
In the slow path of the event reservation, a delta can still be used
if the write_stamp is valid. Instead of using a cmpxchg against the
write stamp, the before_stamp needs to be read again to validate the
write_stamp. The cmpxchg is not needed.
This updates the slowpath to validate the write_stamp by comparing it
to the before_stamp and removes all rb_time_cmpxchg() as there are no
more users of that function.
The removal of the 32-bit updates of rb_time_t will be done in the
next merge window"
* tag 'trace-v6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ring-buffer: Fix slowpath of interrupted event
|
||
|
Andrii Nakryiko
|
d17aff807f |
Revert BPF token-related functionality
This patch includes the following revert (one conflicting BPF FS patch and three token patch sets, represented by merge commits): - revert 0f5d5454c723 "Merge branch 'bpf-fs-mount-options-parsing-follow-ups'"; - revert 750e785796bb "bpf: Support uid and gid when mounting bpffs"; - revert 733763285acf "Merge branch 'bpf-token-support-in-libbpf-s-bpf-object'"; - revert c35919dcce28 "Merge branch 'bpf-token-and-bpf-fs-based-delegation'". Link: https://lore.kernel.org/bpf/CAHk-=wg7JuFYwGy=GOMbRCtOL+jwSQsdUaBsRWkDVYbxipbM5A@mail.gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org> |
||
|
Steven Rostedt (Google)
|
b803d7c664 |
ring-buffer: Fix slowpath of interrupted event
To synchronize the timestamps with the ring buffer reservation, there are
two timestamps that are saved in the buffer meta data.
1. before_stamp
2. write_stamp
When the two are equal, the write_stamp is considered valid, as in, it may
be used to calculate the delta of the next event as the write_stamp is the
timestamp of the previous reserved event on the buffer.
This is done by the following:
/*A*/ w = current position on the ring buffer
before = before_stamp
after = write_stamp
ts = read current timestamp
if (before != after) {
write_stamp is not valid, force adding an absolute
timestamp.
}
/*B*/ before_stamp = ts
/*C*/ write = local_add_return(event length, position on ring buffer)
if (w == write - event length) {
/* Nothing interrupted between A and C */
/*E*/ write_stamp = ts;
delta = ts - after
/*
* If nothing interrupted again,
* before_stamp == write_stamp and write_stamp
* can be used to calculate the delta for
* events that come in after this one.
*/
} else {
/*
* The slow path!
* Was interrupted between A and C.
*/
This is the place that there's a bug. We currently have:
after = write_stamp
ts = read current timestamp
/*F*/ if (write == current position on the ring buffer &&
after < ts && cmpxchg(write_stamp, after, ts)) {
delta = ts - after;
} else {
delta = 0;
}
The assumption is that if the current position on the ring buffer hasn't
moved between C and F, then it also was not interrupted, and that the last
event written has a timestamp that matches the write_stamp. That is the
write_stamp is valid.
But this may not be the case:
If a task context event was interrupted by softirq between B and C.
And the softirq wrote an event that got interrupted by a hard irq between
C and E.
and the hard irq wrote an event (does not need to be interrupted)
We have:
/*B*/ before_stamp = ts of normal context
---> interrupted by softirq
/*B*/ before_stamp = ts of softirq context
---> interrupted by hardirq
/*B*/ before_stamp = ts of hard irq context
/*E*/ write_stamp = ts of hard irq context
/* matches and write_stamp valid */
<----
/*E*/ write_stamp = ts of softirq context
/* No longer matches before_stamp, write_stamp is not valid! */
<---
w != write - length, go to slow path
// Right now the order of events in the ring buffer is:
//
// |-- softirq event --|-- hard irq event --|-- normal context event --|
//
after = write_stamp (this is the ts of softirq)
ts = read current timestamp
if (write == current position on the ring buffer [true] &&
after < ts [true] && cmpxchg(write_stamp, after, ts) [true]) {
delta = ts - after [Wrong!]
The delta is to be between the hard irq event and the normal context
event, but the above logic made the delta between the softirq event and
the normal context event, where the hard irq event is between the two. This
will shift all the remaining event timestamps on the sub-buffer
incorrectly.
The write_stamp is only valid if it matches the before_stamp. The cmpxchg
does nothing to help this.
Instead, the following logic can be done to fix this:
before = before_stamp
ts = read current timestamp
before_stamp = ts
after = write_stamp
if (write == current position on the ring buffer &&
after == before && after < ts) {
delta = ts - after
} else {
delta = 0;
}
The above will only use the write_stamp if it still matches before_stamp
and was tested to not have changed since C.
As a bonus, with this logic we do not need any 64-bit cmpxchg() at all!
This means the 32-bit rb_time_t workaround can finally be removed. But
that's for a later time.
Link: https://lore.kernel.org/linux-trace-kernel/20231218175229.58ec3daf@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20231218230712.3a76b081@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: dd93942570789 ("ring-buffer: Do not try to put back write_stamp")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
||
|
Jakub Kicinski
|
c49b292d03 |
netdev
-----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEE+soXsSLHKoYyzcli6rmadz2vbToFAmWAz2EACgkQ6rmadz2v bToqrw/9EwroZCc8GEHOKAlb/fzrMvn92rLo0ZW/cGN84QJPnx4zM6Zo0+fgLaaN oqqztwMUwdzGC3uX3FfVXaaLKbJ/MeHeL9BXFZNW8zkRHciw4R7kIBhOdPnHyET7 uT+rQ4xPe1Mt7e9PjepKlSL5mEsxWfBkdUgsdn19Z2Vjdfr9mZMhYWYMJGcfTCD1 TwxHKBPhq5fN3IsshmMBB8IrRp1HStUKb65MgZ4dI22LJXxTsFkx5XMFXcmuqvkH NhKj8jDcPEEh31bYcb6aG2Z4onw5F2lquygjk1Qyy5cyw45m/ipJKAXKdAyvJG+R VZCWOET/9wbRwFSK5wxwihCuKghFiofK52i2PcGtXZh0PCouyZZneSJOKM0yVWKO BvuJBxK4ETRnQyN6ZxhuJiEXG3/YMBBhyR2TX1LntVK9ct/k7qFVzATG49J39/sR SYMbptBRj4a5oMJ1qn0nFVEDFkg0jTnTDNnsEpcz60Ayt6EsJ1XosO5yz2huf861 xgRMTKMseyG1/uV45tQ8ZPzbSPpBxjUi9Dl3coYsIm1a+y6clWUXcarONY5KVrpS CR98DuFgl+E7dXuisd/Kz2p2KxxSPq8nytsmLlgOvrUqhwiXqB+TKN8EHgIapVOt l1A5LrzXFTcGlT9MlaWBqEIy83Bu1nqQqbxrAFOE0k8A5jomXaw= =stU2 -----END PGP SIGNATURE----- Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next Alexei Starovoitov says: ==================== pull-request: bpf-next 2023-12-18 This PR is larger than usual and contains changes in various parts of the kernel. The main changes are: 1) Fix kCFI bugs in BPF, from Peter Zijlstra. End result: all forms of indirect calls from BPF into kernel and from kernel into BPF work with CFI enabled. This allows BPF to work with CONFIG_FINEIBT=y. 2) Introduce BPF token object, from Andrii Nakryiko. It adds an ability to delegate a subset of BPF features from privileged daemon (e.g., systemd) through special mount options for userns-bound BPF FS to a trusted unprivileged application. The design accommodates suggestions from Christian Brauner and Paul Moore. Example: $ sudo mkdir -p /sys/fs/bpf/token $ sudo mount -t bpf bpffs /sys/fs/bpf/token \ -o delegate_cmds=prog_load:MAP_CREATE \ -o delegate_progs=kprobe \ -o delegate_attachs=xdp 3) Various verifier improvements and fixes, from Andrii Nakryiko, Andrei Matei. - Complete precision tracking support for register spills - Fix verification of possibly-zero-sized stack accesses - Fix access to uninit stack slots - Track aligned STACK_ZERO cases as imprecise spilled registers. It improves the verifier "instructions processed" metric from single digit to 50-60% for some programs. - Fix verifier retval logic 4) Support for VLAN tag in XDP hints, from Larysa Zaremba. 5) Allocate BPF trampoline via bpf_prog_pack mechanism, from Song Liu. End result: better memory utilization and lower I$ miss for calls to BPF via BPF trampoline. 6) Fix race between BPF prog accessing inner map and parallel delete, from Hou Tao. 7) Add bpf_xdp_get_xfrm_state() kfunc, from Daniel Xu. It allows BPF interact with IPSEC infra. The intent is to support software RSS (via XDP) for the upcoming ipsec pcpu work. Experiments on AWS demonstrate single tunnel pcpu ipsec reaching line rate on 100G ENA nics. 8) Expand bpf_cgrp_storage to support cgroup1 non-attach, from Yafang Shao. 9) BPF file verification via fsverity, from Song Liu. It allows BPF progs get fsverity digest. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (164 commits) bpf: Ensure precise is reset to false in __mark_reg_const_zero() selftests/bpf: Add more uprobe multi fail tests bpf: Fail uprobe multi link with negative offset selftests/bpf: Test the release of map btf s390/bpf: Fix indirect trampoline generation selftests/bpf: Temporarily disable dummy_struct_ops test on s390 x86/cfi,bpf: Fix bpf_exception_cb() signature bpf: Fix dtor CFI cfi: Add CFI_NOSEAL() x86/cfi,bpf: Fix bpf_struct_ops CFI x86/cfi,bpf: Fix bpf_callback_t CFI x86/cfi,bpf: Fix BPF JIT call cfi: Flip headers selftests/bpf: Add test for abnormal cnt during multi-kprobe attachment selftests/bpf: Don't use libbpf_get_error() in kprobe_multi_test selftests/bpf: Add test for abnormal cnt during multi-uprobe attachment bpf: Limit the number of kprobes when attaching program to multiple kprobes bpf: Limit the number of uprobes when attaching program to multiple uprobes bpf: xdp: Register generic_kfunc_set with XDP programs selftests/bpf: utilize string values for delegate_xxx mount options ... ==================== Link: https://lore.kernel.org/r/20231219000520.34178-1-alexei.starovoitov@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
||
|
Andrii Nakryiko
|
8e432e6197 |
bpf: Ensure precise is reset to false in __mark_reg_const_zero()
It is safe to always start with imprecise SCALAR_VALUE register. Previously __mark_reg_const_zero() relied on caller to reset precise mark, but it's very error prone and we already missed it in a few places. So instead make __mark_reg_const_zero() reset precision always, as it's a safe default for SCALAR_VALUE. Explanation is basically the same as for why we are resetting (or rather not setting) precision in current state. If necessary, precision propagation will set it to precise correctly. As such, also remove a big comment about forward precision propagation in mark_reg_stack_read() and avoid unnecessarily setting precision to true after reading from STACK_ZERO stack. Again, precision propagation will correctly handle this, if that SCALAR_VALUE register will ever be needed to be precise. Reported-by: Maxim Mikityanskiy <maxtram95@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Maxim Mikityanskiy <maxtram95@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20231218173601.53047-1-andrii@kernel.org |
||
|
Jiri Olsa
|
3983c00281 |
bpf: Fail uprobe multi link with negative offset
Currently the __uprobe_register will return 0 (success) when called with negative offset. The reason is that the call to register_for_each_vma and then build_map_info won't return error for negative offset. They just won't do anything - no matching vma is found so there's no registered breakpoint for the uprobe. I don't think we can change the behaviour of __uprobe_register and fail for negative uprobe offset, because apps might depend on that already. But I think we can still make the change and check for it on bpf multi link syscall level. Also moving the __get_user call and check for the offsets to the top of loop, to fail early without extra __get_user calls for ref_ctr_offset and cookie arrays. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/bpf/20231217215538.3361991-2-jolsa@kernel.org |
||
|
Linus Torvalds
|
177c2ffe69 |
- Avoid iterating over newly created group leader event's siblings
because there are none, and thus prevent a lockdep splat -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmV/WSEACgkQEsHwGGHe VUoQ7RAAoc9AdZJ8ZmTMLy/5/SS3542z3w3Ts5DxHziZrIzBclRx5RYBw3YgBA2q AgbPIgqr1Y4+45gChhwKIAp7G6g2K8lpqNSJbqP/nFpwkmx7v/m5T/9DH7id1UyQ uRKwxtEAwKz5XeR2czXI5Z+VvG9vIqkrdAR+dSRmcXgcfi8oJCKOywW+n7QFUarf sYWdMQwbMNenl0y/o8MQXmTraQWkRJCqI5JXc23GIkr03z6ZUOwt2qAx2YW4GQQo enXzdk9MokKU4IpRz/rU9j7qaOd9h/AZZXhACSMUVJqDQVDFJJO1rbktKcS17sNH EgRv57xSAYsPvARk2wvw3INEIPOvL4Jb1s86MLa0eN2mH4mVwkqlv/KkUl1/RuHY IuCgpNWliQ3nb6dQeEsp83EW6Ao8FTn3D8+66tbtCVXnMBFQEfUHWFnSfHqcUizb JsRnBA9ke2t3Wu0ph/nZBzck+9kxp0PeUvio//x2IznjfeZ31fQYdVDYU0o8QgOe Ns6MyCn1OcCulfZZTpUbMhy/5FjokKLf2Sfit1r8duDMXVu4cicSnuMUpVPvZd+A 8XcbH73kCO0DuUVtYMbYerFJLgZrcN1gzyPgAmegoaDXBVu4KkOIbXBGEJjv7pPs h5p84zKibyjKhwa+bqlIgy9R9EYb9sPwbNv5eWgQFXzrvQVm5FA= =s8Bq -----END PGP SIGNATURE----- Merge tag 'perf_urgent_for_v6.7_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fix from Borislav Petkov: - Avoid iterating over newly created group leader event's siblings because there are none, and thus prevent a lockdep splat * tag 'perf_urgent_for_v6.7_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf: Fix perf_event_validate_size() lockdep splat |
||
|
Linus Torvalds
|
134fdb80bc |
cxl fixes for 6.7-rc6
- Fix alloc_free_mem_region()'s scan for address space, prevent false
negative out-of-space events
- Fix sleeping lock acquisition from CXL trace event (atomic context)
- Fix put_device() like for the new CXL PMU driver
- Fix wrong pointer freed on error path
- Fixup several lockdep reports (missing lock hold) from new assertion
in cxl_num_decoders_committed() and new tests
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Merge tag 'cxl-fixes-6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl
Pull CXL (Compute Express Link) fixes from Dan Williams:
"A collection of CXL fixes.
The touch outside of drivers/cxl/ is for a helper that allocates
physical address space. Device hotplug tests showed that the driver
failed to utilize (skipped over) valid capacity when allocating a new
memory region. Outside of that, new tests uncovered a small crop of
lockdep reports.
There is also some miscellaneous error path and leak fixups that are
not urgent, but useful to cleanup now.
- Fix alloc_free_mem_region()'s scan for address space, prevent false
negative out-of-space events
- Fix sleeping lock acquisition from CXL trace event (atomic context)
- Fix put_device() like for the new CXL PMU driver
- Fix wrong pointer freed on error path
- Fixup several lockdep reports (missing lock hold) from new
assertion in cxl_num_decoders_committed() and new tests"
* tag 'cxl-fixes-6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
cxl/pmu: Ensure put_device on pmu devices
cxl/cdat: Free correct buffer on checksum error
cxl/hdm: Fix dpa translation locking
kernel/resource: Increment by align value in get_free_mem_region()
cxl: Add cxl_num_decoders_committed() usage to cxl_test
cxl/memdev: Hold region_rwsem during inject and clear poison ops
cxl/core: Always hold region_rwsem while reading poison lists
cxl/hdm: Fix a benign lockdep splat
|
||
|
Linus Torvalds
|
3b8a9b2e68 |
Tracing fixes for v6.7-rc5:
- Fix eventfs to check creating new files for events with names greater than NAME_MAX. The eventfs lookup needs to check the return result of simple_lookup(). - Fix the ring buffer to check the proper max data size. Events must be able to fit on the ring buffer sub-buffer, if it cannot, then it fails to be written and the logic to add the event is avoided. The code to check if an event can fit failed to add the possible absolute timestamp which may make the event not be able to fit. This causes the ring buffer to go into an infinite loop trying to find a sub-buffer that would fit the event. Luckily, there's a check that will bail out if it looped over a 1000 times and it also warns. The real fix is not to add the absolute timestamp to an event that is starting at the beginning of a sub-buffer because it uses the sub-buffer timestamp. By avoiding the timestamp at the start of the sub-buffer allows events that pass the first check to always find a sub-buffer that it can fit on. - Have large events that do not fit on a trace_seq to print "LINE TOO BIG" like it does for the trace_pipe instead of what it does now which is to silently drop the output. - Fix a memory leak of forgetting to free the spare page that is saved by a trace instance. - Update the size of the snapshot buffer when the main buffer is updated if the snapshot buffer is allocated. - Fix ring buffer timestamp logic by removing all the places that tried to put the before_stamp back to the write stamp so that the next event doesn't add an absolute timestamp. But each of these updates added a race where by making the two timestamp equal, it was validating the write_stamp so that it can be incorrectly used for calculating the delta of an event. - There's a temp buffer used for printing the event that was using the event data size for allocation when it needed to use the size of the entire event (meta-data and payload data) - For hardening, use "%.*s" for printing the trace_marker output, to limit the amount that is printed by the size of the event. This was discovered by development that added a bug that truncated the '\0' and caused a crash. - Fix a use-after-free bug in the use of the histogram files when an instance is being removed. - Remove a useless update in the rb_try_to_discard of the write_stamp. The before_stamp was already changed to force the next event to add an absolute timestamp that the write_stamp is not used. But the write_stamp is modified again using an unneeded 64-bit cmpxchg. - Fix several races in the 32-bit implementation of the rb_time_cmpxchg() that does a 64-bit cmpxchg. - While looking at fixing the 64-bit cmpxchg, I noticed that because the ring buffer uses normal cmpxchg, and this can be done in NMI context, there's some architectures that do not have a working cmpxchg in NMI context. For these architectures, fail recording events that happen in NMI context. -----BEGIN PGP SIGNATURE----- iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCZX0nChQccm9zdGVkdEBn b29kbWlzLm9yZwAKCRAp5XQQmuv6qlOMAQD3iegTcceQl9lAsroa3tb3xdweC1GP 51MsX5athxSyoQEAutI/2pBCtLFXgTLMHAMd5F23EM1U9rha7W0myrnvKQY= =d3bS -----END PGP SIGNATURE----- Merge tag 'trace-v6.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix eventfs to check creating new files for events with names greater than NAME_MAX. The eventfs lookup needs to check the return result of simple_lookup(). - Fix the ring buffer to check the proper max data size. Events must be able to fit on the ring buffer sub-buffer, if it cannot, then it fails to be written and the logic to add the event is avoided. The code to check if an event can fit failed to add the possible absolute timestamp which may make the event not be able to fit. This causes the ring buffer to go into an infinite loop trying to find a sub-buffer that would fit the event. Luckily, there's a check that will bail out if it looped over a 1000 times and it also warns. The real fix is not to add the absolute timestamp to an event that is starting at the beginning of a sub-buffer because it uses the sub-buffer timestamp. By avoiding the timestamp at the start of the sub-buffer allows events that pass the first check to always find a sub-buffer that it can fit on. - Have large events that do not fit on a trace_seq to print "LINE TOO BIG" like it does for the trace_pipe instead of what it does now which is to silently drop the output. - Fix a memory leak of forgetting to free the spare page that is saved by a trace instance. - Update the size of the snapshot buffer when the main buffer is updated if the snapshot buffer is allocated. - Fix ring buffer timestamp logic by removing all the places that tried to put the before_stamp back to the write stamp so that the next event doesn't add an absolute timestamp. But each of these updates added a race where by making the two timestamp equal, it was validating the write_stamp so that it can be incorrectly used for calculating the delta of an event. - There's a temp buffer used for printing the event that was using the event data size for allocation when it needed to use the size of the entire event (meta-data and payload data) - For hardening, use "%.*s" for printing the trace_marker output, to limit the amount that is printed by the size of the event. This was discovered by development that added a bug that truncated the '\0' and caused a crash. - Fix a use-after-free bug in the use of the histogram files when an instance is being removed. - Remove a useless update in the rb_try_to_discard of the write_stamp. The before_stamp was already changed to force the next event to add an absolute timestamp that the write_stamp is not used. But the write_stamp is modified again using an unneeded 64-bit cmpxchg. - Fix several races in the 32-bit implementation of the rb_time_cmpxchg() that does a 64-bit cmpxchg. - While looking at fixing the 64-bit cmpxchg, I noticed that because the ring buffer uses normal cmpxchg, and this can be done in NMI context, there's some architectures that do not have a working cmpxchg in NMI context. For these architectures, fail recording events that happen in NMI context. * tag 'trace-v6.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Do not record in NMI if the arch does not support cmpxchg in NMI ring-buffer: Have rb_time_cmpxchg() set the msb counter too ring-buffer: Fix 32-bit rb_time_read() race with rb_time_cmpxchg() ring-buffer: Fix a race in rb_time_cmpxchg() for 32 bit archs ring-buffer: Remove useless update to write_stamp in rb_try_to_discard() ring-buffer: Do not try to put back write_stamp tracing: Fix uaf issue when open the hist or hist_debug file tracing: Add size check when printing trace_marker output ring-buffer: Have saved event hold the entire event ring-buffer: Do not update before stamp when switching sub-buffers tracing: Update snapshot buffer on resize if it is allocated ring-buffer: Fix memory leak of free page eventfs: Fix events beyond NAME_MAX blocking tasks tracing: Have large events show up as '[LINE TOO BIG]' instead of nothing ring-buffer: Fix writing to the buffer with max_data_size |
||
|
Alexei Starovoitov
|
852486b35f |
x86/cfi,bpf: Fix bpf_exception_cb() signature
As per the earlier patches, BPF sub-programs have bpf_callback_t signature and CFI expects callers to have matching signature. This is violated by bpf_prog_aux::bpf_exception_cb(). [peterz: Changelog] Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/CAADnVQ+Z7UcXXBBhMubhcMM=R-dExk-uHtfOLtoLxQ1XxEpqEA@mail.gmail.com Link: https://lore.kernel.org/r/20231215092707.910319166@infradead.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
||
|
Peter Zijlstra
|
e4c0033989 |
bpf: Fix dtor CFI
Ensure the various dtor functions match their prototype and retain their CFI signatures, since they don't have their address taken, they are prone to not getting CFI, making them impossible to call indirectly. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20231215092707.799451071@infradead.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
||
|
Peter Zijlstra
|
2cd3e3772e |
x86/cfi,bpf: Fix bpf_struct_ops CFI
BPF struct_ops uses __arch_prepare_bpf_trampoline() to write trampolines for indirect function calls. These tramplines much have matching CFI. In order to obtain the correct CFI hash for the various methods, add a matching structure that contains stub functions, the compiler will generate correct CFI which we can pilfer for the trampolines. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20231215092707.566977112@infradead.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
||
|
Peter Zijlstra
|
4f9087f166 |
x86/cfi,bpf: Fix BPF JIT call
The current BPF call convention is __nocfi, except when it calls !JIT things, then it calls regular C functions. It so happens that with FineIBT the __nocfi and C calling conventions are incompatible. Specifically __nocfi will call at func+0, while FineIBT will have endbr-poison there, which is not a valid indirect target. Causing #CP. Notably this only triggers on IBT enabled hardware, which is probably why this hasn't been reported (also, most people will have JIT on anyway). Implement proper CFI prologues for the BPF JIT codegen and drop __nocfi for x86. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20231215092707.345270396@infradead.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
||
|
Jens Axboe
|
ae1914174a |
cred: get rid of CONFIG_DEBUG_CREDENTIALS
This code is rarely (never?) enabled by distros, and it hasn't caught anything in decades. Let's kill off this legacy debug code. Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Jens Axboe
|
f8fa5d7692 |
cred: switch to using atomic_long_t
There are multiple ways to grab references to credentials, and the only protection we have against overflowing it is the memory required to do so. With memory sizes only moving in one direction, let's bump the reference count to 64-bit and move it outside the realm of feasibly overflowing. Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Hou Tao
|
d6d1e6c17c |
bpf: Limit the number of kprobes when attaching program to multiple kprobes
An abnormally big cnt may also be assigned to kprobe_multi.cnt when
attaching multiple kprobes. It will trigger the following warning in
kvmalloc_node():
if (unlikely(size > INT_MAX)) {
WARN_ON_ONCE(!(flags & __GFP_NOWARN));
return NULL;
}
Fix the warning by limiting the maximal number of kprobes in
bpf_kprobe_multi_link_attach(). If the number of kprobes is greater than
MAX_KPROBE_MULTI_CNT, the attachment will fail and return -E2BIG.
Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231215100708.2265609-3-houtao@huaweicloud.com
|
||
|
Hou Tao
|
8b2efe51ba |
bpf: Limit the number of uprobes when attaching program to multiple uprobes
An abnormally big cnt may be passed to link_create.uprobe_multi.cnt,
and it will trigger the following warning in kvmalloc_node():
if (unlikely(size > INT_MAX)) {
WARN_ON_ONCE(!(flags & __GFP_NOWARN));
return NULL;
}
Fix the warning by limiting the maximal number of uprobes in
bpf_uprobe_multi_link_attach(). If the number of uprobes is greater than
MAX_UPROBE_MULTI_CNT, the attachment will return -E2BIG.
Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link")
Reported-by: Xingwei Lee <xrivendell7@gmail.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Closes: https://lore.kernel.org/bpf/CABOYnLwwJY=yFAGie59LFsUsBAgHfroVqbzZ5edAXbFE3YiNVA@mail.gmail.com
Link: https://lore.kernel.org/bpf/20231215100708.2265609-2-houtao@huaweicloud.com
|
||
|
Linus Torvalds
|
a62aa88ba1 |
17 hotfixes. 8 are cc:stable and the other 9 pertain to post-6.6 issues.
-----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCZXxs8wAKCRDdBJ7gKXxA junbAQCdItfHHinkWziciOrb0387wW+5WZ1ohqRFW8pGYLuasQEArpKmw13bvX7z e+ec9K1Ek9MlIsO2RwORR4KHH4MAbwA= =YpZh -----END PGP SIGNATURE----- Merge tag 'mm-hotfixes-stable-2023-12-15-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull misc fixes from Andrew Morton: "17 hotfixes. 8 are cc:stable and the other 9 pertain to post-6.6 issues" * tag 'mm-hotfixes-stable-2023-12-15-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: mm/mglru: reclaim offlined memcgs harder mm/mglru: respect min_ttl_ms with memcgs mm/mglru: try to stop at high watermarks mm/mglru: fix underprotected page cache mm/shmem: fix race in shmem_undo_range w/THP Revert "selftests: error out if kernel header files are not yet built" crash_core: fix the check for whether crashkernel is from high memory x86, kexec: fix the wrong ifdeffery CONFIG_KEXEC sh, kexec: fix the incorrect ifdeffery and dependency of CONFIG_KEXEC mips, kexec: fix the incorrect ifdeffery and dependency of CONFIG_KEXEC m68k, kexec: fix the incorrect ifdeffery and build dependency of CONFIG_KEXEC loongarch, kexec: change dependency of object files mm/damon/core: make damon_start() waits until kdamond_fn() starts selftests/mm: cow: print ksft header before printing anything else mm: fix VMA heap bounds checking riscv: fix VMALLOC_START definition kexec: drop dependency on ARCH_SUPPORTS_KEXEC from CRASH_DUMP |
||
|
Steven Rostedt (Google)
|
712292308a |
ring-buffer: Do not record in NMI if the arch does not support cmpxchg in NMI
As the ring buffer recording requires cmpxchg() to work, if the architecture does not support cmpxchg in NMI, then do not do any recording within an NMI. Link: https://lore.kernel.org/linux-trace-kernel/20231213175403.6fc18540@gandalf.local.home Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Steven Rostedt (Google)
|
0aa0e5289c |
ring-buffer: Have rb_time_cmpxchg() set the msb counter too
The rb_time_cmpxchg() on 32-bit architectures requires setting three 32-bit words to represent the 64-bit timestamp, with some salt for synchronization. Those are: msb, top, and bottom The issue is, the rb_time_cmpxchg() did not properly salt the msb portion, and the msb that was written was stale. Link: https://lore.kernel.org/linux-trace-kernel/20231215084114.20899342@rorschach.local.home Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Fixes: f03f2abce4f39 ("ring-buffer: Have 32 bit time stamps use all 64 bits") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Mathieu Desnoyers
|
dec890089b |
ring-buffer: Fix 32-bit rb_time_read() race with rb_time_cmpxchg()
The following race can cause rb_time_read() to observe a corrupted time
stamp:
rb_time_cmpxchg()
[...]
if (!rb_time_read_cmpxchg(&t->msb, msb, msb2))
return false;
if (!rb_time_read_cmpxchg(&t->top, top, top2))
return false;
<interrupted before updating bottom>
__rb_time_read()
[...]
do {
c = local_read(&t->cnt);
top = local_read(&t->top);
bottom = local_read(&t->bottom);
msb = local_read(&t->msb);
} while (c != local_read(&t->cnt));
*cnt = rb_time_cnt(top);
/* If top and msb counts don't match, this interrupted a write */
if (*cnt != rb_time_cnt(msb))
return false;
^ this check fails to catch that "bottom" is still not updated.
So the old "bottom" value is returned, which is wrong.
Fix this by checking that all three of msb, top, and bottom 2-bit cnt
values match.
The reason to favor checking all three fields over requiring a specific
update order for both rb_time_set() and rb_time_cmpxchg() is because
checking all three fields is more robust to handle partial failures of
rb_time_cmpxchg() when interrupted by nested rb_time_set().
Link: https://lore.kernel.org/lkml/20231211201324.652870-1-mathieu.desnoyers@efficios.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231212193049.680122-1-mathieu.desnoyers@efficios.com
Fixes: f458a1453424e ("ring-buffer: Test last update in 32bit version of __rb_time_read()")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
||
|
Steven Rostedt (Google)
|
fff88fa0fb |
ring-buffer: Fix a race in rb_time_cmpxchg() for 32 bit archs
Mathieu Desnoyers pointed out an issue in the rb_time_cmpxchg() for 32 bit
architectures. That is:
static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set)
{
unsigned long cnt, top, bottom, msb;
unsigned long cnt2, top2, bottom2, msb2;
u64 val;
/* The cmpxchg always fails if it interrupted an update */
if (!__rb_time_read(t, &val, &cnt2))
return false;
if (val != expect)
return false;
<<<< interrupted here!
cnt = local_read(&t->cnt);
The problem is that the synchronization counter in the rb_time_t is read
*after* the value of the timestamp is read. That means if an interrupt
were to come in between the value being read and the counter being read,
it can change the value and the counter and the interrupted process would
be clueless about it!
The counter needs to be read first and then the value. That way it is easy
to tell if the value is stale or not. If the counter hasn't been updated,
then the value is still good.
Link: https://lore.kernel.org/linux-trace-kernel/20231211201324.652870-1-mathieu.desnoyers@efficios.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231212115301.7a9c9a64@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: 10464b4aa605e ("ring-buffer: Add rb_time_t 64 bit operations for speeding up 32 bit")
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
||
|
Steven Rostedt (Google)
|
083e9f65bd |
ring-buffer: Remove useless update to write_stamp in rb_try_to_discard()
When filtering is enabled, a temporary buffer is created to place the content of the trace event output so that the filter logic can decide from the trace event output if the trace event should be filtered out or not. If it is to be filtered out, the content in the temporary buffer is simply discarded, otherwise it is written into the trace buffer. But if an interrupt were to come in while a previous event was using that temporary buffer, the event written by the interrupt would actually go into the ring buffer itself to prevent corrupting the data on the temporary buffer. If the event is to be filtered out, the event in the ring buffer is discarded, or if it fails to discard because another event were to have already come in, it is turned into padding. The update to the write_stamp in the rb_try_to_discard() happens after a fix was made to force the next event after the discard to use an absolute timestamp by setting the before_stamp to zero so it does not match the write_stamp (which causes an event to use the absolute timestamp). But there's an effort in rb_try_to_discard() to put back the write_stamp to what it was before the event was added. But this is useless and wasteful because nothing is going to be using that write_stamp for calculations as it still will not match the before_stamp. Remove this useless update, and in doing so, we remove another cmpxchg64()! Also update the comments to reflect this change as well as remove some extra white space in another comment. Link: https://lore.kernel.org/linux-trace-kernel/20231215081810.1f4f38fe@rorschach.local.home Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Vincent Donnefort <vdonnefort@google.com> Fixes: b2dd797543cf ("ring-buffer: Force absolute timestamp on discard of event") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Steven Rostedt (Google)
|
dd93942570 |
ring-buffer: Do not try to put back write_stamp
If an update to an event is interrupted by another event between the time the initial event allocated its buffer and where it wrote to the write_stamp, the code try to reset the write stamp back to the what it had just overwritten. It knows that it was overwritten via checking the before_stamp, and if it didn't match what it wrote to the before_stamp before it allocated its space, it knows it was overwritten. To put back the write_stamp, it uses the before_stamp it read. The problem here is that by writing the before_stamp to the write_stamp it makes the two equal again, which means that the write_stamp can be considered valid as the last timestamp written to the ring buffer. But this is not necessarily true. The event that interrupted the event could have been interrupted in a way that it was interrupted as well, and can end up leaving with an invalid write_stamp. But if this happens and returns to this context that uses the before_stamp to update the write_stamp again, it can possibly incorrectly make it valid, causing later events to have in correct time stamps. As it is OK to leave this function with an invalid write_stamp (one that doesn't match the before_stamp), there's no reason to try to make it valid again in this case. If this race happens, then just leave with the invalid write_stamp and the next event to come along will just add a absolute timestamp and validate everything again. Bonus points: This gets rid of another cmpxchg64! Link: https://lore.kernel.org/linux-trace-kernel/20231214222921.193037a7@gandalf.local.home Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Vincent Donnefort <vdonnefort@google.com> Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Mark Rutland
|
7e2c1e4b34 |
perf: Fix perf_event_validate_size() lockdep splat
When lockdep is enabled, the for_each_sibling_event(sibling, event)
macro checks that event->ctx->mutex is held. When creating a new group
leader event, we call perf_event_validate_size() on a partially
initialized event where event->ctx is NULL, and so when
for_each_sibling_event() attempts to check event->ctx->mutex, we get a
splat, as reported by Lucas De Marchi:
WARNING: CPU: 8 PID: 1471 at kernel/events/core.c:1950 __do_sys_perf_event_open+0xf37/0x1080
This only happens for a new event which is its own group_leader, and in
this case there cannot be any sibling events. Thus it's safe to skip the
check for siblings, which avoids having to make invasive and ugly
changes to for_each_sibling_event().
Avoid the splat by bailing out early when the new event is its own
group_leader.
Fixes: 382c27f4ed28f803 ("perf: Fix perf_event_validate_size()")
Closes: https://lore.kernel.org/lkml/20231214000620.3081018-1-lucas.demarchi@intel.com/
Closes: https://lore.kernel.org/lkml/ZXpm6gQ%2Fd59jGsuW@xpf.sh.intel.com/
Reported-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reported-by: Pengfei Xu <pengfei.xu@intel.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231215112450.3972309-1-mark.rutland@arm.com
|
||
|
Daniel Xu
|
7489723c2e |
bpf: xdp: Register generic_kfunc_set with XDP programs
Registering generic_kfunc_set with XDP programs enables some of the newer BPF features inside XDP -- namely tree based data structures and BPF exceptions. The current motivation for this commit is to enable assertions inside XDP bpf progs. Assertions are a standard and useful tool to encode intent. Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Link: https://lore.kernel.org/r/d07d4614b81ca6aada44fcb89bb6b618fb66e4ca.1702594357.git.dxu@dxuuu.xyz Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
||
|
Andrii Nakryiko
|
c5707b2146 |
bpf: support symbolic BPF FS delegation mount options
Besides already supported special "any" value and hex bit mask, support
string-based parsing of delegation masks based on exact enumerator
names. Utilize BTF information of `enum bpf_cmd`, `enum bpf_map_type`,
`enum bpf_prog_type`, and `enum bpf_attach_type` types to find supported
symbolic names (ignoring __MAX_xxx guard values and stripping repetitive
prefixes like BPF_ for cmd and attach types, BPF_MAP_TYPE_ for maps, and
BPF_PROG_TYPE_ for prog types). The case doesn't matter, but it is
normalized to lower case in mount option output. So "PROG_LOAD",
"prog_load", and "MAP_create" are all valid values to specify for
delegate_cmds options, "array" is among supported for map types, etc.
Besides supporting string values, we also support multiple values
specified at the same time, using colon (':') separator.
There are corresponding changes on bpf_show_options side to use known
values to print them in human-readable format, falling back to hex mask
printing, if there are any unrecognized bits. This shouldn't be
necessary when enum BTF information is present, but in general we should
always be able to fall back to this even if kernel was built without BTF.
As mentioned, emitted symbolic names are normalized to be all lower case.
Example below shows various ways to specify delegate_cmds options
through mount command and how mount options are printed back:
12/14 14:39:07.604
vmuser@archvm:~/local/linux/tools/testing/selftests/bpf
$ mount | rg token
$ sudo mkdir -p /sys/fs/bpf/token
$ sudo mount -t bpf bpffs /sys/fs/bpf/token \
-o delegate_cmds=prog_load:MAP_CREATE \
-o delegate_progs=kprobe \
-o delegate_attachs=xdp
$ mount | grep token
bpffs on /sys/fs/bpf/token type bpf (rw,relatime,delegate_cmds=map_create:prog_load,delegate_progs=kprobe,delegate_attachs=xdp)
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231214225016.1209867-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
||
|
Jakub Kicinski
|
8f674972d6 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR.
Conflicts:
drivers/net/ethernet/intel/iavf/iavf_ethtool.c
3a0b5a2929fd ("iavf: Introduce new state machines for flow director")
95260816b489 ("iavf: use iavf_schedule_aq_request() helper")
https://lore.kernel.org/all/84e12519-04dc-bd80-bc34-8cf50d7898ce@intel.com/
drivers/net/ethernet/broadcom/bnxt/bnxt.c
c13e268c0768 ("bnxt_en: Fix HWTSTAMP_FILTER_ALL packet timestamp logic")
c2f8063309da ("bnxt_en: Refactor RX VLAN acceleration logic.")
a7445d69809f ("bnxt_en: Add support for new RX and TPA_START completion types for P7")
1c7fd6ee2fe4 ("bnxt_en: Rename some macros for the P5 chips")
https://lore.kernel.org/all/20231211110022.27926ad9@canb.auug.org.au/
drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c
bd6781c18cb5 ("bnxt_en: Fix wrong return value check in bnxt_close_nic()")
84793a499578 ("bnxt_en: Skip nic close/open when configuring tstamp filters")
https://lore.kernel.org/all/20231214113041.3a0c003c@canb.auug.org.au/
drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c
3d7a3f2612d7 ("net/mlx5: Nack sync reset request when HotPlug is enabled")
cecf44ea1a1f ("net/mlx5: Allow sync reset flow when BF MGT interface device is present")
https://lore.kernel.org/all/20231211110328.76c925af@canb.auug.org.au/
No adjacent changes.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
||
|
Yonghong Song
|
59e5791f59 |
bpf: Fix a race condition between btf_put() and map_free()
When running `./test_progs -j` in my local vm with latest kernel, I once hit a kasan error like below: [ 1887.184724] BUG: KASAN: slab-use-after-free in bpf_rb_root_free+0x1f8/0x2b0 [ 1887.185599] Read of size 4 at addr ffff888106806910 by task kworker/u12:2/2830 [ 1887.186498] [ 1887.186712] CPU: 3 PID: 2830 Comm: kworker/u12:2 Tainted: G OEL 6.7.0-rc3-00699-g90679706d486-dirty #494 [ 1887.188034] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 1887.189618] Workqueue: events_unbound bpf_map_free_deferred [ 1887.190341] Call Trace: [ 1887.190666] <TASK> [ 1887.190949] dump_stack_lvl+0xac/0xe0 [ 1887.191423] ? nf_tcp_handle_invalid+0x1b0/0x1b0 [ 1887.192019] ? panic+0x3c0/0x3c0 [ 1887.192449] print_report+0x14f/0x720 [ 1887.192930] ? preempt_count_sub+0x1c/0xd0 [ 1887.193459] ? __virt_addr_valid+0xac/0x120 [ 1887.194004] ? bpf_rb_root_free+0x1f8/0x2b0 [ 1887.194572] kasan_report+0xc3/0x100 [ 1887.195085] ? bpf_rb_root_free+0x1f8/0x2b0 [ 1887.195668] bpf_rb_root_free+0x1f8/0x2b0 [ 1887.196183] ? __bpf_obj_drop_impl+0xb0/0xb0 [ 1887.196736] ? preempt_count_sub+0x1c/0xd0 [ 1887.197270] ? preempt_count_sub+0x1c/0xd0 [ 1887.197802] ? _raw_spin_unlock+0x1f/0x40 [ 1887.198319] bpf_obj_free_fields+0x1d4/0x260 [ 1887.198883] array_map_free+0x1a3/0x260 [ 1887.199380] bpf_map_free_deferred+0x7b/0xe0 [ 1887.199943] process_scheduled_works+0x3a2/0x6c0 [ 1887.200549] worker_thread+0x633/0x890 [ 1887.201047] ? __kthread_parkme+0xd7/0xf0 [ 1887.201574] ? kthread+0x102/0x1d0 [ 1887.202020] kthread+0x1ab/0x1d0 [ 1887.202447] ? pr_cont_work+0x270/0x270 [ 1887.202954] ? kthread_blkcg+0x50/0x50 [ 1887.203444] ret_from_fork+0x34/0x50 [ 1887.203914] ? kthread_blkcg+0x50/0x50 [ 1887.204397] ret_from_fork_asm+0x11/0x20 [ 1887.204913] </TASK> [ 1887.204913] </TASK> [ 1887.205209] [ 1887.205416] Allocated by task 2197: [ 1887.205881] kasan_set_track+0x3f/0x60 [ 1887.206366] __kasan_kmalloc+0x6e/0x80 [ 1887.206856] __kmalloc+0xac/0x1a0 [ 1887.207293] btf_parse_fields+0xa15/0x1480 [ 1887.207836] btf_parse_struct_metas+0x566/0x670 [ 1887.208387] btf_new_fd+0x294/0x4d0 [ 1887.208851] __sys_bpf+0x4ba/0x600 [ 1887.209292] __x64_sys_bpf+0x41/0x50 [ 1887.209762] do_syscall_64+0x4c/0xf0 [ 1887.210222] entry_SYSCALL_64_after_hwframe+0x63/0x6b [ 1887.210868] [ 1887.211074] Freed by task 36: [ 1887.211460] kasan_set_track+0x3f/0x60 [ 1887.211951] kasan_save_free_info+0x28/0x40 [ 1887.212485] ____kasan_slab_free+0x101/0x180 [ 1887.213027] __kmem_cache_free+0xe4/0x210 [ 1887.213514] btf_free+0x5b/0x130 [ 1887.213918] rcu_core+0x638/0xcc0 [ 1887.214347] __do_softirq+0x114/0x37e The error happens at bpf_rb_root_free+0x1f8/0x2b0: 00000000000034c0 <bpf_rb_root_free>: ; { 34c0: f3 0f 1e fa endbr64 34c4: e8 00 00 00 00 callq 0x34c9 <bpf_rb_root_free+0x9> 34c9: 55 pushq %rbp 34ca: 48 89 e5 movq %rsp, %rbp ... ; if (rec && rec->refcount_off >= 0 && 36aa: 4d 85 ed testq %r13, %r13 36ad: 74 a9 je 0x3658 <bpf_rb_root_free+0x198> 36af: 49 8d 7d 10 leaq 0x10(%r13), %rdi 36b3: e8 00 00 00 00 callq 0x36b8 <bpf_rb_root_free+0x1f8> <==== kasan function 36b8: 45 8b 7d 10 movl 0x10(%r13), %r15d <==== use-after-free load 36bc: 45 85 ff testl %r15d, %r15d 36bf: 78 8c js 0x364d <bpf_rb_root_free+0x18d> So the problem is at rec->refcount_off in the above. I did some source code analysis and find the reason. CPU A CPU B bpf_map_put: ... btf_put with rcu callback ... bpf_map_free_deferred with system_unbound_wq ... ... ... ... btf_free_rcu: ... ... ... bpf_map_free_deferred: ... ... ... ---------> btf_struct_metas_free() ... | race condition ... ... ---------> map->ops->map_free() ... ... btf->struct_meta_tab = NULL In the above, map_free() corresponds to array_map_free() and eventually calling bpf_rb_root_free() which calls: ... __bpf_obj_drop_impl(obj, field->graph_root.value_rec, false); ... Here, 'value_rec' is assigned in btf_check_and_fixup_fields() with following code: meta = btf_find_struct_meta(btf, btf_id); if (!meta) return -EFAULT; rec->fields[i].graph_root.value_rec = meta->record; So basically, 'value_rec' is a pointer to the record in struct_metas_tab. And it is possible that that particular record has been freed by btf_struct_metas_free() and hence we have a kasan error here. Actually it is very hard to reproduce the failure with current bpf/bpf-next code, I only got the above error once. To increase reproducibility, I added a delay in bpf_map_free_deferred() to delay map->ops->map_free(), which significantly increased reproducibility. diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 5e43ddd1b83f..aae5b5213e93 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -695,6 +695,7 @@ static void bpf_map_free_deferred(struct work_struct *work) struct bpf_map *map = container_of(work, struct bpf_map, work); struct btf_record *rec = map->record; + mdelay(100); security_bpf_map_free(map); bpf_map_release_memcg(map); /* implementation dependent freeing */ Hao also provided test cases ([1]) for easily reproducing the above issue. There are two ways to fix the issue, the v1 of the patch ([2]) moving btf_put() after map_free callback, and the v5 of the patch ([3]) using a kptr style fix which tries to get a btf reference during map_check_btf(). Each approach has its pro and cons. The first approach delays freeing btf while the second approach needs to acquire reference depending on context which makes logic not very elegant and may complicate things with future new data structures. Alexei suggested in [4] going back to v1 which is what this patch tries to do. Rerun './test_progs -j' with the above mdelay() hack for a couple of times and didn't observe the error for the above rb_root test cases. Running Hou's test ([1]) is also successful. [1] https://lore.kernel.org/bpf/20231207141500.917136-1-houtao@huaweicloud.com/ [2] v1: https://lore.kernel.org/bpf/20231204173946.3066377-1-yonghong.song@linux.dev/ [3] v5: https://lore.kernel.org/bpf/20231208041621.2968241-1-yonghong.song@linux.dev/ [4] v4: https://lore.kernel.org/bpf/CAADnVQJ3FiXUhZJwX_81sjZvSYYKCFB3BT6P8D59RS2Gu+0Z7g@mail.gmail.com/ Cc: Hou Tao <houtao@huaweicloud.com> Fixes: 958cf2e273f0 ("bpf: Introduce bpf_obj_new") Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20231214203815.1469107-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Hou Tao
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dc68540913 |
bpf: Use GFP_KERNEL in bpf_event_entry_gen()
rcu_read_lock() is no longer held when invoking bpf_event_entry_gen() which is called by perf_event_fd_array_get_ptr(), so using GFP_KERNEL instead of GFP_ATOMIC to reduce the possibility of failures due to out-of-memory. Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20231214043010.3458072-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Hou Tao
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8f82583f95 |
bpf: Reduce the scope of rcu_read_lock when updating fd map
There is no rcu-read-lock requirement for ops->map_fd_get_ptr() or ops->map_fd_put_ptr(), so doesn't use rcu-read-lock for these two callbacks. For bpf_fd_array_map_update_elem(), accessing array->ptrs doesn't need rcu-read-lock because array->ptrs must still be allocated. For bpf_fd_htab_map_update_elem(), htab_map_update_elem() only requires rcu-read-lock to be held to avoid the WARN_ON_ONCE(), so only use rcu_read_lock() during the invocation of htab_map_update_elem(). Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20231214043010.3458072-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Zheng Yejian
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1cc111b9cd |
tracing: Fix uaf issue when open the hist or hist_debug file
KASAN report following issue. The root cause is when opening 'hist'
file of an instance and accessing 'trace_event_file' in hist_show(),
but 'trace_event_file' has been freed due to the instance being removed.
'hist_debug' file has the same problem. To fix it, call
tracing_{open,release}_file_tr() in file_operations callback to have
the ref count and avoid 'trace_event_file' being freed.
BUG: KASAN: slab-use-after-free in hist_show+0x11e0/0x1278
Read of size 8 at addr ffff242541e336b8 by task head/190
CPU: 4 PID: 190 Comm: head Not tainted 6.7.0-rc5-g26aff849438c #133
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x98/0xf8
show_stack+0x1c/0x30
dump_stack_lvl+0x44/0x58
print_report+0xf0/0x5a0
kasan_report+0x80/0xc0
__asan_report_load8_noabort+0x1c/0x28
hist_show+0x11e0/0x1278
seq_read_iter+0x344/0xd78
seq_read+0x128/0x1c0
vfs_read+0x198/0x6c8
ksys_read+0xf4/0x1e0
__arm64_sys_read+0x70/0xa8
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Allocated by task 188:
kasan_save_stack+0x28/0x50
kasan_set_track+0x28/0x38
kasan_save_alloc_info+0x20/0x30
__kasan_slab_alloc+0x6c/0x80
kmem_cache_alloc+0x15c/0x4a8
trace_create_new_event+0x84/0x348
__trace_add_new_event+0x18/0x88
event_trace_add_tracer+0xc4/0x1a0
trace_array_create_dir+0x6c/0x100
trace_array_create+0x2e8/0x568
instance_mkdir+0x48/0x80
tracefs_syscall_mkdir+0x90/0xe8
vfs_mkdir+0x3c4/0x610
do_mkdirat+0x144/0x200
__arm64_sys_mkdirat+0x8c/0xc0
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Freed by task 191:
kasan_save_stack+0x28/0x50
kasan_set_track+0x28/0x38
kasan_save_free_info+0x34/0x58
__kasan_slab_free+0xe4/0x158
kmem_cache_free+0x19c/0x508
event_file_put+0xa0/0x120
remove_event_file_dir+0x180/0x320
event_trace_del_tracer+0xb0/0x180
__remove_instance+0x224/0x508
instance_rmdir+0x44/0x78
tracefs_syscall_rmdir+0xbc/0x140
vfs_rmdir+0x1cc/0x4c8
do_rmdir+0x220/0x2b8
__arm64_sys_unlinkat+0xc0/0x100
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Link: https://lore.kernel.org/linux-trace-kernel/20231214012153.676155-1-zhengyejian1@huawei.com
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Hou Tao
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2a0c6b41ee |
bpf: Update the comments in maybe_wait_bpf_programs()
Since commit 638e4b825d52 ("bpf: Allows per-cpu maps and map-in-map in
sleepable programs"), sleepable BPF program can also use map-in-map, but
maybe_wait_bpf_programs() doesn't handle it accordingly. The main reason
is that using synchronize_rcu_tasks_trace() to wait for the completions
of these sleepable BPF programs may incur a very long delay and
userspace may think it is hung, so the wait for sleepable BPF programs
is skipped. Update the comments in maybe_wait_bpf_programs() to reflect
the reason.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20231211083447.1921178-1-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Matt Bobrowski
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b13cddf633 |
bpf: add small subset of SECURITY_PATH hooks to BPF sleepable_lsm_hooks list
security_path_* based LSM hooks appear to be generally missing from the sleepable_lsm_hooks list. Initially add a small subset of them to the preexisting sleepable_lsm_hooks list so that sleepable BPF helpers like bpf_d_path() can be used from sleepable BPF LSM based programs. The security_path_* hooks added in this patch are similar to the security_inode_* counterparts that already exist in the sleepable_lsm_hooks list, and are called in roughly similar points and contexts. Presumably, making them OK to be also annotated as sleepable. Building a kernel with DEBUG_ATOMIC_SLEEP options enabled and running reasonable workloads stimulating activity that would be intercepted by such security hooks didn't show any splats. Notably, I haven't added all the security_path_* LSM hooks that are available as I don't need them at this point in time. Signed-off-by: Matt Bobrowski <mattbobrowski@google.com> Acked-by: KP Singh <kpsingh@kernel.org> Link: https://lore.kernel.org/r/ZXM3IHHXpNY9y82a@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |