This is a note to let you know that I've just added the patch titled
net: Find dst with sk's xfrm policy not ctl_sk
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-find-dst-with-sk-s-xfrm-policy-not-ctl_sk.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e22aa14866684f77b4f6b6cae98539e520ddb731 Mon Sep 17 00:00:00 2001
From: sewookseo <sewookseo@xxxxxxxxxx>
Date: Thu, 7 Jul 2022 10:01:39 +0000
Subject: net: Find dst with sk's xfrm policy not ctl_sk
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From: sewookseo <sewookseo@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Cc: Sehee Lee <seheele@xxxxxxxxxx>
Signed-off-by: Sewook Seo <sewookseo@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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,
Patches currently in stable-queue which might be from sewookseo@xxxxxxxxxx are
queue-5.15/net-find-dst-with-sk-s-xfrm-policy-not-ctl_sk.patch
