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| author | Daniel Borkmann <daniel@iogearbox.net> | 2016-07-22 01:19:42 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-07-25 10:34:11 -0700 |
| commit | aa7145c16d6bf086538ad7eb20c807513bfa5efc (patch) | |
| tree | dbaccc895163a74c9b87c71eeff8c1f59d4f2a9e /kernel/events | |
| parent | a1b43eddaec5a3fea55e1581caf217abda2d3147 (diff) | |
| download | linux-aa7145c16d6bf086538ad7eb20c807513bfa5efc.tar.bz2 | |
bpf, events: fix offset in skb copy handler
This patch fixes the __output_custom() routine we currently use with
bpf_skb_copy(). I missed that when len is larger than the size of the
current handle, we can issue multiple invocations of copy_func, and
__output_custom() advances destination but also source buffer by the
written amount of bytes. When we have __output_custom(), this is actually
wrong since in that case the source buffer points to a non-linear object,
in our case an skb, which the copy_func helper is supposed to walk.
Therefore, since this is non-linear we thus need to pass the offset into
the helper, so that copy_func can use it for extracting the data from
the source object.
Therefore, adjust the callback signatures properly and pass offset
into the skb_header_pointer() invoked from bpf_skb_copy() callback. The
__DEFINE_OUTPUT_COPY_BODY() is adjusted to accommodate for two things:
i) to pass in whether we should advance source buffer or not; this is
a compile-time constant condition, ii) to pass in the offset for
__output_custom(), which we do with help of __VA_ARGS__, so everything
can stay inlined as is currently. Both changes allow for adapting the
__output_* fast-path helpers w/o extra overhead.
Fixes: 555c8a8623a3 ("bpf: avoid stack copy and use skb ctx for event output")
Fixes: 7e3f977edd0b ("perf, events: add non-linear data support for raw records")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/internal.h | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/kernel/events/internal.h b/kernel/events/internal.h index 2417eb5512cd..486fd78eb8d5 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -123,18 +123,19 @@ static inline unsigned long perf_aux_size(struct ring_buffer *rb) return rb->aux_nr_pages << PAGE_SHIFT; } -#define __DEFINE_OUTPUT_COPY_BODY(memcpy_func) \ +#define __DEFINE_OUTPUT_COPY_BODY(advance_buf, memcpy_func, ...) \ { \ unsigned long size, written; \ \ do { \ size = min(handle->size, len); \ - written = memcpy_func(handle->addr, buf, size); \ + written = memcpy_func(__VA_ARGS__); \ written = size - written; \ \ len -= written; \ handle->addr += written; \ - buf += written; \ + if (advance_buf) \ + buf += written; \ handle->size -= written; \ if (!handle->size) { \ struct ring_buffer *rb = handle->rb; \ @@ -153,12 +154,16 @@ static inline unsigned long perf_aux_size(struct ring_buffer *rb) static inline unsigned long \ func_name(struct perf_output_handle *handle, \ const void *buf, unsigned long len) \ -__DEFINE_OUTPUT_COPY_BODY(memcpy_func) +__DEFINE_OUTPUT_COPY_BODY(true, memcpy_func, handle->addr, buf, size) static inline unsigned long __output_custom(struct perf_output_handle *handle, perf_copy_f copy_func, const void *buf, unsigned long len) -__DEFINE_OUTPUT_COPY_BODY(copy_func) +{ + unsigned long orig_len = len; + __DEFINE_OUTPUT_COPY_BODY(false, copy_func, handle->addr, buf, + orig_len - len, size) +} static inline unsigned long memcpy_common(void *dst, const void *src, unsigned long n) |