commit 6807352353561187a718e87204458999dbcbba1b upstream.
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.
The flowi4_l3mdev field doesn't exist in the linux-5.15.y branch. The field flowi4_oif is used instead to get the l3 master device.
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 Signed-off-by: Nicolas Dichtel nicolas.dichtel@6wind.com --- net/ipv4/fib_semantics.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index 735901b8c9f6..188f87ffff69 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -2286,6 +2286,15 @@ 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 = l3mdev_master_dev_rcu(dev_get_by_index_rcu(net, fl4->flowi4_oif)); + + 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); + } }