From 4f0c40d94461cfd23893a17335b2ab78ecb333c8 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Tue, 12 Jul 2016 18:18:57 -0400 Subject: dccp: limit sk_filter trim to payload Dccp verifies packet integrity, including length, at initial rcv in dccp_invalid_packet, later pulls headers in dccp_enqueue_skb. A call to sk_filter in-between can cause __skb_pull to wrap skb->len. skb_copy_datagram_msg interprets this as a negative value, so (correctly) fails with EFAULT. The negative length is reported in ioctl SIOCINQ or possibly in a DCCP_WARN in dccp_close. Introduce an sk_receive_skb variant that caps how small a filter program can trim packets, and call this in dccp with the header length. Excessively trimmed packets are now processed normally and queued for reception as 0B payloads. Fixes: 7c657876b63c ("[DCCP]: Initial implementation") Signed-off-by: Willem de Bruijn Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- include/net/sock.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'include/net/sock.h') diff --git a/include/net/sock.h b/include/net/sock.h index 649d2a8c17fc..ff5be7e8ddea 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1576,7 +1576,13 @@ static inline void sock_put(struct sock *sk) */ void sock_gen_put(struct sock *sk); -int sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested); +int __sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested, + unsigned int trim_cap); +static inline int sk_receive_skb(struct sock *sk, struct sk_buff *skb, + const int nested) +{ + return __sk_receive_skb(sk, skb, nested, 1); +} static inline void sk_tx_queue_set(struct sock *sk, int tx_queue) { -- cgit v1.2.3-59-g8ed1b