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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 /net
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 'net')
-rw-r--r--net/core/filter.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index 0b521353008d..5708999f8a79 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2026,9 +2026,9 @@ bool bpf_helper_changes_skb_data(void *func)
}
static unsigned long bpf_skb_copy(void *dst_buff, const void *skb,
- unsigned long len)
+ unsigned long off, unsigned long len)
{
- void *ptr = skb_header_pointer(skb, 0, len, dst_buff);
+ void *ptr = skb_header_pointer(skb, off, len, dst_buff);
if (unlikely(!ptr))
return len;