4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Stefano Brivio sbrivio@redhat.com
[ Upstream commit a8c6db1dfd1b1d18359241372bb204054f2c3174 ]
In fib_nh_match(), if output interface or gateway are passed in the FIB configuration, we don't have to check next hops of multipath routes to conclude whether we have a match or not.
However, we might still have routes with different realms matching the same output interface and gateway configuration, and this needs to cause the match to fail. Otherwise the first route inserted in the FIB will match, regardless of the realms:
# ip route add 1.1.1.1 dev eth0 table 1234 realms 1/2 # ip route append 1.1.1.1 dev eth0 table 1234 realms 3/4 # ip route list table 1234 1.1.1.1 dev eth0 scope link realms 1/2 1.1.1.1 dev eth0 scope link realms 3/4 # ip route del 1.1.1.1 dev ens3 table 1234 realms 3/4 # ip route list table 1234 1.1.1.1 dev ens3 scope link realms 3/4
whereas route with realms 3/4 should have been deleted instead.
Explicitly check for fc_flow passed in the FIB configuration (this comes from RTA_FLOW extracted by rtm_to_fib_config()) and fail matching if it differs from nh_tclassid.
The handling of RTA_FLOW for multipath routes later in fib_nh_match() is still needed, as we can have multiple RTA_FLOW attributes that need to be matched against the tclassid of each next hop.
v2: Check that fc_flow is set before discarding the match, so that the user can still select the first matching rule by not specifying any realm, as suggested by David Ahern.
Reported-by: Jianlin Shi jishi@redhat.com Signed-off-by: Stefano Brivio sbrivio@redhat.com Acked-by: David Ahern dsahern@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/fib_semantics.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -654,6 +654,11 @@ int fib_nh_match(struct fib_config *cfg, fi->fib_nh, cfg, extack)) return 1; } +#ifdef CONFIG_IP_ROUTE_CLASSID + if (cfg->fc_flow && + cfg->fc_flow != fi->fib_nh->nh_tclassid) + return 1; +#endif if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) && (!cfg->fc_gw || cfg->fc_gw == fi->fib_nh->nh_gw)) return 0;