Subject: [PATCH 28/29] ip: Fix SO_MARK in RST, ACK and ICMP packets

From: Willem de Bruijn <[email-masked]>
Date: Wed, 1 Jul 2020 16:00:06 -0400

[ Upstream commit 0da7536fb47f51df89ccfcb1fa09f249d9accec5 ]

When no full socket is available, skbs are sent over a per-netns
control socket. Its sk_mark is temporarily adjusted to match that
of the real (request or timewait) socket or to reflect an incoming
skb, so that the outgoing skb inherits this in __ip_make_skb.

Introduction of the socket cookie mark field broke this. Now the
skb is set through the cookie and cork:

<caller>		# init sockc.mark from sk_mark or cmsg
ip_append_data
  ip_setup_cork		# convert sockc.mark to cork mark
ip_push_pending_frames
  ip_finish_skb
    __ip_make_skb	# set skb->mark to cork mark

But I missed these special control sockets. Update all callers of
__ip(6)_make_skb that were originally missed.

For IPv6, the same two icmp(v6) paths are affected. The third
case is not, as commit 92e55f412cff ("tcp: don't annotate
mark on control socket from tcp_v6_send_response()") replaced
the ctl_sk->sk_mark with passing the mark field directly as a
function argument. That commit predates the commit that
introduced the bug.

Fixes: c6af0c227a22 ("ip: support SO_MARK cmsg")
Signed-off-by: Willem de Bruijn <[email-masked]>
Reported-by: Martin KaFai Lau <[email-masked]>
Reviewed-by: Martin KaFai Lau <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/ipv4/icmp.c      | 4 ++--
 net/ipv4/ip_output.c | 2 +-
 net/ipv6/icmp.c      | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index ac95ba78b903..73f46cb5e51d 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -427,7 +427,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 
 	ipcm_init(&ipc);
 	inet->tos = ip_hdr(skb)->tos;
-	sk->sk_mark = mark;
+	ipc.sockc.mark = mark;
 	daddr = ipc.addr = ip_hdr(skb)->saddr;
 	saddr = fib_compute_spec_dst(skb);
 
@@ -709,10 +709,10 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
 	icmp_param.skb	  = skb_in;
 	icmp_param.offset = skb_network_offset(skb_in);
 	inet_sk(sk)->tos = tos;
-	sk->sk_mark = mark;
 	ipcm_init(&ipc);
 	ipc.addr = iph->saddr;
 	ipc.opt = &icmp_param.replyopts.opt;
+	ipc.sockc.mark = mark;
 
 	rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
 			       type, code, &icmp_param);
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index b268ee1c1b44..b36c4a3159e5 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1704,7 +1704,7 @@ void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
 	sk->sk_protocol = ip_hdr(skb)->protocol;
 	sk->sk_bound_dev_if = arg->bound_dev_if;
 	sk->sk_sndbuf = sysctl_wmem_default;
-	sk->sk_mark = fl4.flowi4_mark;
+	ipc.sockc.mark = fl4.flowi4_mark;
 	err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
 			     len, 0, &ipc, &rt, MSG_DONTWAIT);
 	if (unlikely(err)) {
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 62c997201970..7d3a3894f785 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -535,7 +535,6 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
 	if (!sk)
 		goto out_bh_enable;
 
-	sk->sk_mark = mark;
 	np = inet6_sk(sk);
 
 	if (!icmpv6_xrlim_allow(sk, type, &fl6))
@@ -552,6 +551,7 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
 		fl6.flowi6_oif = np->ucast_oif;
 
 	ipcm6_init_sk(&ipc6, np);
+	ipc6.sockc.mark = mark;
 	fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
 
 	dst = icmpv6_route_lookup(net, skb, sk, &fl6);
@@ -720,7 +720,6 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
 	sk = icmpv6_xmit_lock(net);
 	if (!sk)
 		goto out_bh_enable;
-	sk->sk_mark = mark;
 	np = inet6_sk(sk);
 
 	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
@@ -748,6 +747,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
 	ipcm6_init_sk(&ipc6, np);
 	ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 	ipc6.tclass = ipv6_get_dsfield(ipv6_hdr(skb));
+	ipc6.sockc.mark = mark;
 
 	if (ip6_append_data(sk, icmpv6_getfrag, &msg,
 			    skb->len + sizeof(struct icmp6hdr),
-- 
2.26.2