diff options
| author | Willem de Bruijn <willemb@google.com> | 2016-04-07 18:12:59 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-04-13 22:24:52 -0400 |
| commit | 31c2e4926fe912f88388bcaa8450fcaa8f2ece47 (patch) | |
| tree | 0c1883a4c4c478746162c66befa7d5d0f8e79dc8 | |
| parent | 9f9a45beaa96188085d52d273c2ecb052c7d8d27 (diff) | |
udp: do not expect udp headers in recv cmsg IP_CMSG_CHECKSUM
On udp sockets, recv cmsg IP_CMSG_CHECKSUM returns a checksum over
the packet payload. Since commit e6afc8ace6dd pulled the headers,
taking skb->data as the start of transport header is incorrect. Use
the transport header pointer.
Also, when peeking at an offset from the start of the packet, only
return a checksum from the start of the peeked data. Note that the
cmsg does not subtract a tail checkum when reading truncated data.
Fixes: e6afc8ace6dd ("udp: remove headers from UDP packets before queueing")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/ip_sockglue.c | 3 | ||||
| -rw-r--r-- | net/ipv4/udp.c | 2 |
2 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 89b5f3bd6694..279471c4e58f 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -106,7 +106,8 @@ static void ip_cmsg_recv_checksum(struct msghdr *msg, struct sk_buff *skb, return; if (offset != 0) - csum = csum_sub(csum, csum_partial(skb->data, offset, 0)); + csum = csum_sub(csum, csum_partial(skb_transport_header(skb), + offset, 0)); put_cmsg(msg, SOL_IP, IP_CHECKSUM, sizeof(__wsum), &csum); } diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index d2d294b0a1f1..f1863136d3e4 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1375,7 +1375,7 @@ try_again: *addr_len = sizeof(*sin); } if (inet->cmsg_flags) - ip_cmsg_recv_offset(msg, skb, sizeof(struct udphdr)); + ip_cmsg_recv_offset(msg, skb, sizeof(struct udphdr) + off); err = copied; if (flags & MSG_TRUNC) |