From bbadb9a222b4f0c3fec01483b57cbb403df0076a Mon Sep 17 00:00:00 2001 From: Florian Larysch Date: Fri, 7 Apr 2017 14:42:20 +0200 Subject: [PATCH] net: ipv4: fix multipath RTM_GETROUTE behavior when iif is given inet_rtm_getroute synthesizes a skeletal ICMP skb, which is passed to ip_route_input when iif is given. If a multipath route is present for the designated destination, fib_multipath_hash ends up being called with that skb. However, as that skb contains no information beyond the protocol type, the calculated hash does not match the one we would see for a real packet. There is currently no way to fix this for layer 4 hashing, as RTM_GETROUTE doesn't have the necessary information to create layer 4 headers. To fix this for layer 3 hashing, set appropriate saddr/daddrs in the skb and also change the protocol to UDP to avoid special treatment for ICMP. Signed-off-by: Florian Larysch Signed-off-by: David S. Miller --- net/ipv4/route.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 5dda1ef81c7e..5e1e60546fce 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2667,10 +2667,6 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh) skb_reset_mac_header(skb); skb_reset_network_header(skb); - /* Bugfix: need to give ip_route_input enough of an IP header to not gag. */ - ip_hdr(skb)->protocol = IPPROTO_ICMP; - skb_reserve(skb, MAX_HEADER + sizeof(struct iphdr)); - src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0; dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0; iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0; @@ -2680,6 +2676,15 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh) else uid = (iif ? INVALID_UID : current_uid()); + /* Bugfix: need to give ip_route_input enough of an IP header to + * not gag. + */ + ip_hdr(skb)->protocol = IPPROTO_UDP; + ip_hdr(skb)->saddr = src; + ip_hdr(skb)->daddr = dst; + + skb_reserve(skb, MAX_HEADER + sizeof(struct iphdr)); + memset(&fl4, 0, sizeof(fl4)); fl4.daddr = dst; fl4.saddr = src; -- 2.20.1