From 9b6c14d51bd2304b92f842e96172a9cc822fc77c Mon Sep 17 00:00:00 2001 From: David Ahern Date: Wed, 9 Nov 2016 09:07:26 -0800 Subject: net: tcp response should set oif only if it is L3 master Lorenzo noted an Android unit test failed due to e0d56fdd7342: "The expectation in the test was that the RST replying to a SYN sent to a closed port should be generated with oif=0. In other words it should not prefer the interface where the SYN came in on, but instead should follow whatever the routing table says it should do." Revert the change to ip_send_unicast_reply and tcp_v6_send_response such that the oif in the flow is set to the skb_iif only if skb_iif is an L3 master. Fixes: e0d56fdd7342 ("net: l3mdev: remove redundant calls") Reported-by: Lorenzo Colitti Signed-off-by: David Ahern Tested-by: Lorenzo Colitti Acked-by: Lorenzo Colitti Signed-off-by: David S. Miller --- net/ipv6/tcp_ipv6.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'net/ipv6/tcp_ipv6.c') diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 5a27ab4eab39..6ca23c2e76f7 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -818,8 +818,12 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32 fl6.flowi6_proto = IPPROTO_TCP; if (rt6_need_strict(&fl6.daddr) && !oif) fl6.flowi6_oif = tcp_v6_iif(skb); - else - fl6.flowi6_oif = oif ? : skb->skb_iif; + else { + if (!oif && netif_index_is_l3_master(net, skb->skb_iif)) + oif = skb->skb_iif; + + fl6.flowi6_oif = oif; + } fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark); fl6.fl6_dport = t1->dest; -- cgit v1.2.3 From ac6e780070e30e4c35bd395acfe9191e6268bdd3 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Nov 2016 13:12:35 -0800 Subject: tcp: take care of truncations done by sk_filter() With syzkaller help, Marco Grassi found a bug in TCP stack, crashing in tcp_collapse() Root cause is that sk_filter() can truncate the incoming skb, but TCP stack was not really expecting this to happen. It probably was expecting a simple DROP or ACCEPT behavior. We first need to make sure no part of TCP header could be removed. Then we need to adjust TCP_SKB_CB(skb)->end_seq Many thanks to syzkaller team and Marco for giving us a reproducer. Signed-off-by: Eric Dumazet Reported-by: Marco Grassi Reported-by: Vladis Dronov Signed-off-by: David S. Miller --- include/net/tcp.h | 1 + net/ipv4/tcp_ipv4.c | 19 ++++++++++++++++++- net/ipv6/tcp_ipv6.c | 6 ++++-- 3 files changed, 23 insertions(+), 3 deletions(-) (limited to 'net/ipv6/tcp_ipv6.c') diff --git a/include/net/tcp.h b/include/net/tcp.h index 304a8e17bc87..123979fe12bf 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1220,6 +1220,7 @@ static inline void tcp_prequeue_init(struct tcp_sock *tp) bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb); +int tcp_filter(struct sock *sk, struct sk_buff *skb); #undef STATE_TRACE diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 61b7be303eec..2259114c7242 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1564,6 +1564,21 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb) } EXPORT_SYMBOL(tcp_add_backlog); +int tcp_filter(struct sock *sk, struct sk_buff *skb) +{ + struct tcphdr *th = (struct tcphdr *)skb->data; + unsigned int eaten = skb->len; + int err; + + err = sk_filter_trim_cap(sk, skb, th->doff * 4); + if (!err) { + eaten -= skb->len; + TCP_SKB_CB(skb)->end_seq -= eaten; + } + return err; +} +EXPORT_SYMBOL(tcp_filter); + /* * From tcp_input.c */ @@ -1676,8 +1691,10 @@ process: nf_reset(skb); - if (sk_filter(sk, skb)) + if (tcp_filter(sk, skb)) goto discard_and_relse; + th = (const struct tcphdr *)skb->data; + iph = ip_hdr(skb); skb->dev = NULL; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 6ca23c2e76f7..b9f1fee9a886 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1229,7 +1229,7 @@ static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb) if (skb->protocol == htons(ETH_P_IP)) return tcp_v4_do_rcv(sk, skb); - if (sk_filter(sk, skb)) + if (tcp_filter(sk, skb)) goto discard; /* @@ -1457,8 +1457,10 @@ process: if (tcp_v6_inbound_md5_hash(sk, skb)) goto discard_and_relse; - if (sk_filter(sk, skb)) + if (tcp_filter(sk, skb)) goto discard_and_relse; + th = (const struct tcphdr *)skb->data; + hdr = ipv6_hdr(skb); skb->dev = NULL; -- cgit v1.2.3