netdev - [PATCH v3 net-next] sock: Reset dst when changing sk

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Message-ID: <20181108141335.GA29455@konacove.com>
Date:   Thu, 8 Nov 2018 08:13:35 -0600
From:   David Barmann <david.barmann@...ckpath.com>
To:     netdev <netdev@...r.kernel.org>
Subject: [PATCH v3 net-next] sock: Reset dst when changing sk_mark via
 setsockopt

When setting the SO_MARK socket option, if the mark changes, the dst
needs to be reset so that a new route lookup is performed.

This fixes the case where an application wants to change routing by
setting a new sk_mark.  If this is done after some packets have already
been sent, the dst is cached and has no effect.

Signed-off-by: David Barmann <david.barmann@...ckpath.com>
---
 net/core/sock.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 7b304e454a38..6d7e189e3cd9 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -952,10 +952,12 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
 			clear_bit(SOCK_PASSSEC, &sock->flags);
 		break;
 	case SO_MARK:
-		if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
+		if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {
 			ret = -EPERM;
-		else
+		} else if (val != sk->sk_mark) {
 			sk->sk_mark = val;
+			sk_dst_reset(sk);
+		}
 		break;
 
 	case SO_RXQ_OVFL:
-- 
2.14.5