netdev - [PATCH net-next 3/4] net/ipv6: use ipv6_fl_get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250724131828.32155-4-equinox@diac24.net>
Date: Thu, 24 Jul 2025 15:18:24 +0200
From: David Lamparter <equinox@...c24.net>
To: netdev@...r.kernel.org,
	David Ahern <dsahern@...nel.org>,
	"David S. Miller" <davem@...emloft.net>
Cc: David Lamparter <equinox@...c24.net>,
	Lorenzo Colitti <lorenzo@...gle.com>,
	Patrick Rohr <prohr@...gle.com>
Subject: [PATCH net-next 3/4] net/ipv6: use ipv6_fl_get_saddr in output

Flatten ip6_route_get_saddr() into ip6_dst_lookup_tail (which really
just means handling fib6_prefsrc), and then replace ipv6_dev_get_saddr
with ipv6_fl_get_saddr to pass down the flow information.

Signed-off-by: David Lamparter <equinox@...c24.net>
Cc: Lorenzo Colitti <lorenzo@...gle.com>
Cc: Patrick Rohr <prohr@...gle.com>
---
 net/ipv6/ip6_output.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 0412f8544695..eeda556f275f 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1111,31 +1111,44 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
 	struct neighbour *n;
 	struct rt6_info *rt;
 #endif
-	int err;
+	int err = 0;
 	int flags = 0;
 
 	/* The correct way to handle this would be to do
-	 * ip6_route_get_saddr, and then ip6_route_output; however,
+	 * ipv6_fl_get_saddr, and then ip6_route_output; however,
 	 * the route-specific preferred source forces the
-	 * ip6_route_output call _before_ ip6_route_get_saddr.
+	 * ip6_route_output call _before_ ipv6_fl_get_saddr.
 	 *
 	 * In source specific routing (no src=any default route),
 	 * ip6_route_output will fail given src=any saddr, though, so
 	 * that's why we try it again later.
 	 */
 	if (ipv6_addr_any(&fl6->saddr)) {
+		struct net_device *l3mdev;
+		struct net_device *dev;
 		struct fib6_info *from;
 		struct rt6_info *rt;
+		bool same_vrf;
+		int err = 0;
 
 		*dst = ip6_route_output(net, sk, fl6);
 		rt = (*dst)->error ? NULL : dst_rt6_info(*dst);
 
 		rcu_read_lock();
 		from = rt ? rcu_dereference(rt->from) : NULL;
-		err = ip6_route_get_saddr(net, from, &fl6->daddr,
-					  sk ? READ_ONCE(inet6_sk(sk)->srcprefs) : 0,
-					  fl6->flowi6_l3mdev,
-					  &fl6->saddr);
+
+		l3mdev = dev_get_by_index_rcu(net, fl6->flowi6_l3mdev);
+		if (!from || !from->fib6_prefsrc.plen || l3mdev)
+			dev = from ? fib6_info_nh_dev(from) : NULL;
+		same_vrf = !l3mdev || l3mdev_master_dev_rcu(dev) == l3mdev;
+		if (from && from->fib6_prefsrc.plen && same_vrf)
+			fl6->saddr = from->fib6_prefsrc.addr;
+		else
+			err = ipv6_fl_get_saddr(net, *dst,
+						same_vrf ? dev : l3mdev, sk,
+						sk ? READ_ONCE(inet6_sk(sk)->srcprefs) : 0,
+						fl6);
+
 		rcu_read_unlock();
 
 		if (err)
-- 
2.47.2