The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 6807352353561187a718e87204458999dbcbba1b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024072916-pastrami-suction-5192@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

680735235356 ("ipv4: fix source address selection with route leak")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6807352353561187a718e87204458999dbcbba1b Mon Sep 17 00:00:00 2001 From: Nicolas Dichtel nicolas.dichtel@6wind.com Date: Wed, 10 Jul 2024 10:14:27 +0200 Subject: [PATCH] ipv4: fix source address selection with route leak

By default, an address assigned to the output interface is selected when the source address is not specified. This is problematic when a route, configured in a vrf, uses an interface from another vrf (aka route leak). The original vrf does not own the selected source address.

Let's add a check against the output interface and call the appropriate function to select the source address.

CC: stable@vger.kernel.org Fixes: 8cbb512c923d ("net: Add source address lookup op for VRF") Signed-off-by: Nicolas Dichtel nicolas.dichtel@6wind.com Reviewed-by: David Ahern dsahern@kernel.org Link: https://patch.msgid.link/20240710081521.3809742-2-nicolas.dichtel@6wind.com Signed-off-by: Jakub Kicinski kuba@kernel.org

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index f669da98d11d..8956026bc0a2 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -2270,6 +2270,15 @@ void fib_select_path(struct net *net, struct fib_result *res, fib_select_default(fl4, res);

check_saddr: - if (!fl4->saddr) - fl4->saddr = fib_result_prefsrc(net, res); + if (!fl4->saddr) { + struct net_device *l3mdev; + + l3mdev = dev_get_by_index_rcu(net, fl4->flowi4_l3mdev); + + if (!l3mdev || + l3mdev_master_dev_rcu(FIB_RES_DEV(*res)) == l3mdev) + fl4->saddr = fib_result_prefsrc(net, res); + else + fl4->saddr = inet_select_addr(l3mdev, 0, RT_SCOPE_LINK); + } }