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| author | Daniel Borkmann <daniel@iogearbox.net> | 2016-02-19 23:05:26 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-02-21 22:07:10 -0500 |
| commit | 2f72959a9c1260ade234f353ccca91118151af66 (patch) | |
| tree | fdd08812be172d834752c55f580889256341e1a9 /net/core | |
| parent | 3697649ff29e0f647565eed04b27a7779c646a22 (diff) | |
| download | linux-2f72959a9c1260ade234f353ccca91118151af66.tar.gz linux-2f72959a9c1260ade234f353ccca91118151af66.tar.bz2 linux-2f72959a9c1260ade234f353ccca91118151af66.zip | |
bpf: fix csum update in bpf_l4_csum_replace helper for udp
When using this helper for updating UDP checksums, we need to extend
this in order to write CSUM_MANGLED_0 for csum computations that result
into 0 as sum. Reason we need this is because packets with a checksum
could otherwise become incorrectly marked as a packet without a checksum.
Likewise, if the user indicates BPF_F_MARK_MANGLED_0, then we should
not turn packets without a checksum into ones with a checksum.
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/core')
| -rw-r--r-- | net/core/filter.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index f031b82128f3..8a0b8c3eb189 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1477,10 +1477,12 @@ static u64 bpf_l4_csum_replace(u64 r1, u64 r2, u64 from, u64 to, u64 flags) { struct sk_buff *skb = (struct sk_buff *) (long) r1; bool is_pseudo = flags & BPF_F_PSEUDO_HDR; + bool is_mmzero = flags & BPF_F_MARK_MANGLED_0; int offset = (int) r2; __sum16 sum, *ptr; - if (unlikely(flags & ~(BPF_F_PSEUDO_HDR | BPF_F_HDR_FIELD_MASK))) + if (unlikely(flags & ~(BPF_F_MARK_MANGLED_0 | BPF_F_PSEUDO_HDR | + BPF_F_HDR_FIELD_MASK))) return -EINVAL; if (unlikely((u32) offset > 0xffff)) return -EFAULT; @@ -1490,6 +1492,8 @@ static u64 bpf_l4_csum_replace(u64 r1, u64 r2, u64 from, u64 to, u64 flags) ptr = skb_header_pointer(skb, offset, sizeof(sum), &sum); if (unlikely(!ptr)) return -EFAULT; + if (is_mmzero && !*ptr) + return 0; switch (flags & BPF_F_HDR_FIELD_MASK) { case 0: @@ -1508,6 +1512,8 @@ static u64 bpf_l4_csum_replace(u64 r1, u64 r2, u64 from, u64 to, u64 flags) return -EINVAL; } + if (is_mmzero && !*ptr) + *ptr = CSUM_MANGLED_0; if (ptr == &sum) /* skb_store_bits guaranteed to not return -EFAULT here */ skb_store_bits(skb, offset, ptr, sizeof(sum)); |