From 2dc49d1680b534877fd20cce52557ea542bb06b6 Mon Sep 17 00:00:00 2001 From: Nicolas Dichtel Date: Mon, 22 Dec 2014 18:22:48 +0100 Subject: [PATCH] tcp6: don't move IP6CB before xfrm6_policy_check() When xfrm6_policy_check() is used, _decode_session6() is called after some intermediate functions. This function uses IP6CB(), thus TCP_SKB_CB() must be prepared after the call of xfrm6_policy_check(). Before this patch, scenarii with IPv6 + TCP + IPsec Transport are broken. Fixes: 971f10eca186 ("tcp: better TCP_SKB_CB layout to reduce cache line misses") Reported-by: Huaibin Wang Suggested-by: Eric Dumazet Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller --- net/ipv6/tcp_ipv6.c | 45 +++++++++++++++++++++++++++++---------------- 1 file changed, 29 insertions(+), 16 deletions(-) diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 5ff87805258e..9c0b54e87b47 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1387,6 +1387,28 @@ ipv6_pktoptions: return 0; } +static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr, + const struct tcphdr *th) +{ + /* This is tricky: we move IP6CB at its correct location into + * TCP_SKB_CB(). It must be done after xfrm6_policy_check(), because + * _decode_session6() uses IP6CB(). + * barrier() makes sure compiler won't play aliasing games. + */ + memmove(&TCP_SKB_CB(skb)->header.h6, IP6CB(skb), + sizeof(struct inet6_skb_parm)); + barrier(); + + TCP_SKB_CB(skb)->seq = ntohl(th->seq); + TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + + skb->len - th->doff*4); + TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); + TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); + TCP_SKB_CB(skb)->tcp_tw_isn = 0; + TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr); + TCP_SKB_CB(skb)->sacked = 0; +} + static int tcp_v6_rcv(struct sk_buff *skb) { const struct tcphdr *th; @@ -1418,24 +1440,9 @@ static int tcp_v6_rcv(struct sk_buff *skb) th = tcp_hdr(skb); hdr = ipv6_hdr(skb); - /* This is tricky : We move IPCB at its correct location into TCP_SKB_CB() - * barrier() makes sure compiler wont play fool^Waliasing games. - */ - memmove(&TCP_SKB_CB(skb)->header.h6, IP6CB(skb), - sizeof(struct inet6_skb_parm)); - barrier(); - - TCP_SKB_CB(skb)->seq = ntohl(th->seq); - TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + - skb->len - th->doff*4); - TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); - TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); - TCP_SKB_CB(skb)->tcp_tw_isn = 0; - TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr); - TCP_SKB_CB(skb)->sacked = 0; sk = __inet6_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest, - tcp_v6_iif(skb)); + inet6_iif(skb)); if (!sk) goto no_tcp_socket; @@ -1451,6 +1458,8 @@ process: if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_and_relse; + tcp_v6_fill_cb(skb, hdr, th); + #ifdef CONFIG_TCP_MD5SIG if (tcp_v6_inbound_md5_hash(sk, skb)) goto discard_and_relse; @@ -1482,6 +1491,8 @@ no_tcp_socket: if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) goto discard_it; + tcp_v6_fill_cb(skb, hdr, th); + if (skb->len < (th->doff<<2) || tcp_checksum_complete(skb)) { csum_error: TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS); @@ -1505,6 +1516,8 @@ do_time_wait: goto discard_it; } + tcp_v6_fill_cb(skb, hdr, th); + if (skb->len < (th->doff<<2)) { inet_twsk_put(inet_twsk(sk)); goto bad_packet; -- 2.20.1