diff options
| 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 | |
| parent | bpf: try harder on clones when writing into skb (diff) | |
| download | linux-dev-2f72959a9c1260ade234f353ccca91118151af66.tar.xz linux-dev-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>
| -rw-r--r-- | include/uapi/linux/bpf.h | 1 | ||||
| -rw-r--r-- | net/core/filter.c | 8 |
2 files changed, 8 insertions, 1 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 48d0a6c54609..6496f98d3d68 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -313,6 +313,7 @@ enum bpf_func_id { /* BPF_FUNC_l4_csum_replace flags. */ #define BPF_F_PSEUDO_HDR (1ULL << 4) +#define BPF_F_MARK_MANGLED_0 (1ULL << 5) /* BPF_FUNC_clone_redirect and BPF_FUNC_redirect flags. */ #define BPF_F_INGRESS (1ULL << 0) 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)); |