From: Xin Long lucien.xin@gmail.com
[ Upstream commit 0a90478b93a46bdcd56ba33c37566a993e455d54 ]
With the topo:
h1 ---| rp1 | | route rp3 |--- h3 (192.168.200.1) h2 ---| rp2 |
If rp1 bc_forwarding is set while rp2 bc_forwarding is not, after doing "ping 192.168.200.255" on h1, then ping 192.168.200.255 on h2, and the packets can still be forwared.
This issue was caused by the input route cache. It should only do the cache for either bc forwarding or local delivery. Otherwise, local delivery can use the route cache for bc forwarding of other interfaces.
This patch is to fix it by not doing cache for local delivery if all.bc_forwarding is enabled.
Note that we don't fix it by checking route cache local flag after rt_cache_valid() in "local_input:" and "ip_mkroute_input", as the common route code shouldn't be touched for bc_forwarding.
Fixes: 5cbf777cfdf6 ("route: add support for directed broadcast forwarding") Reported-by: Jianlin Shi jishi@redhat.com Signed-off-by: Xin Long lucien.xin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/route.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)
--- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1960,7 +1960,7 @@ static int ip_route_input_slow(struct sk u32 itag = 0; struct rtable *rth; struct flowi4 fl4; - bool do_cache; + bool do_cache = true;
/* IP on this device is disabled. */
@@ -2037,6 +2037,9 @@ static int ip_route_input_slow(struct sk if (res->type == RTN_BROADCAST) { if (IN_DEV_BFORWARD(in_dev)) goto make_route; + /* not do cache if bc_forwarding is enabled */ + if (IPV4_DEVCONF_ALL(net, BC_FORWARDING)) + do_cache = false; goto brd_input; }
@@ -2074,16 +2077,13 @@ brd_input: RT_CACHE_STAT_INC(in_brd);
local_input: - do_cache = false; - if (res->fi) { - if (!itag) { - rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input); - if (rt_cache_valid(rth)) { - skb_dst_set_noref(skb, &rth->dst); - err = 0; - goto out; - } - do_cache = true; + do_cache &= res->fi && !itag; + if (do_cache) { + rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input); + if (rt_cache_valid(rth)) { + skb_dst_set_noref(skb, &rth->dst); + err = 0; + goto out; } }