From: sewookseo sewookseo@google.com
commit e22aa14866684f77b4f6b6cae98539e520ddb731 upstream.
If we set XFRM security policy by calling setsockopt with option IPV6_XFRM_POLICY, the policy will be stored in 'sock_policy' in 'sock' struct. However tcp_v6_send_response doesn't look up dst_entry with the actual socket but looks up with tcp control socket. This may cause a problem that a RST packet is sent without ESP encryption & peer's TCP socket can't receive it. This patch will make the function look up dest_entry with actual socket, if the socket has XFRM policy(sock_policy), so that the TCP response packet via this function can be encrypted, & aligned on the encrypted TCP socket.
Tested: We encountered this problem when a TCP socket which is encrypted in ESP transport mode encryption, receives challenge ACK at SYN_SENT state. After receiving challenge ACK, TCP needs to send RST to establish the socket at next SYN try. But the RST was not encrypted & peer TCP socket still remains on ESTABLISHED state. So we verified this with test step as below. [Test step] 1. Making a TCP state mismatch between client(IDLE) & server(ESTABLISHED). 2. Client tries a new connection on the same TCP ports(src & dst). 3. Server will return challenge ACK instead of SYN,ACK. 4. Client will send RST to server to clear the SOCKET. 5. Client will retransmit SYN to server on the same TCP ports. [Expected result] The TCP connection should be established.
Cc: Maciej Żenczykowski maze@google.com Cc: Eric Dumazet edumazet@google.com Cc: Steffen Klassert steffen.klassert@secunet.com Cc: Sehee Lee seheele@google.com Signed-off-by: Sewook Seo sewookseo@google.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/xfrm.h | 2 ++ net/ipv4/ip_output.c | 2 +- net/ipv4/tcp_ipv4.c | 2 ++ net/ipv6/tcp_ipv6.c | 5 ++++- 4 files changed, 9 insertions(+), 2 deletions(-)
--- a/include/net/xfrm.h +++ b/include/net/xfrm.h @@ -1190,6 +1190,8 @@ int __xfrm_sk_clone_policy(struct sock *
static inline int xfrm_sk_clone_policy(struct sock *sk, const struct sock *osk) { + if (!sk_fullsock(osk)) + return 0; sk->sk_policy[0] = NULL; sk->sk_policy[1] = NULL; if (unlikely(osk->sk_policy[0] || osk->sk_policy[1])) --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1704,7 +1704,7 @@ void ip_send_unicast_reply(struct sock * tcp_hdr(skb)->source, tcp_hdr(skb)->dest, arg->uid); security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); - rt = ip_route_output_key(net, &fl4); + rt = ip_route_output_flow(net, &fl4, sk); if (IS_ERR(rt)) return;
--- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -817,6 +817,7 @@ static void tcp_v4_send_reset(const stru ctl_sk->sk_priority = (sk->sk_state == TCP_TIME_WAIT) ? inet_twsk(sk)->tw_priority : sk->sk_priority; transmit_time = tcp_transmit_time(sk); + xfrm_sk_clone_policy(ctl_sk, sk); } ip_send_unicast_reply(ctl_sk, skb, &TCP_SKB_CB(skb)->header.h4.opt, @@ -825,6 +826,7 @@ static void tcp_v4_send_reset(const stru transmit_time);
ctl_sk->sk_mark = 0; + xfrm_sk_free_policy(ctl_sk); sock_net_set(ctl_sk, &init_net); __TCP_INC_STATS(net, TCP_MIB_OUTSEGS); __TCP_INC_STATS(net, TCP_MIB_OUTRSTS); --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1001,7 +1001,10 @@ static void tcp_v6_send_response(const s * Underlying function will use this to retrieve the network * namespace */ - dst = ip6_dst_lookup_flow(sock_net(ctl_sk), ctl_sk, &fl6, NULL); + if (sk && sk->sk_state != TCP_TIME_WAIT) + dst = ip6_dst_lookup_flow(net, sk, &fl6, NULL); /*sk's xfrm_policy can be referred*/ + else + dst = ip6_dst_lookup_flow(net, ctl_sk, &fl6, NULL); if (!IS_ERR(dst)) { skb_dst_set(buff, dst); ip6_xmit(ctl_sk, buff, &fl6, fl6.flowi6_mark, NULL,