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authorDaniel Borkmann <daniel@iogearbox.net>2016-07-22 01:19:42 +0200
committerDavid S. Miller <davem@davemloft.net>2016-07-25 10:34:11 -0700
commitaa7145c16d6bf086538ad7eb20c807513bfa5efc (patch)
treedbaccc895163a74c9b87c71eeff8c1f59d4f2a9e /kernel/events
parenta1b43eddaec5a3fea55e1581caf217abda2d3147 (diff)
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.h15
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)