From 4f858c56bdac801728b8983d7b542ae0e263e7e6 Mon Sep 17 00:00:00 2001 From: Alexey Kodanev Date: Tue, 3 Apr 2018 15:00:10 +0300 Subject: [PATCH] ipv6: udp: set dst cache for a connected sk if current not valid A new RTF_CACHE route can be created between ip6_sk_dst_lookup_flow() and ip6_dst_store() calls in udpv6_sendmsg(), when datagram sending results to ICMPV6_PKT_TOOBIG error: udp_v6_send_skb(), for example with vti6 tunnel: vti6_xmit(), get ICMPV6_PKT_TOOBIG error skb_dst_update_pmtu(), can create a RTF_CACHE clone icmpv6_send() ... udpv6_err() ip6_sk_update_pmtu() ip6_update_pmtu(), can create a RTF_CACHE clone ... ip6_datagram_dst_update() ip6_dst_store() And after commit 33c162a980fe ("ipv6: datagram: Update dst cache of a connected datagram sk during pmtu update"), the UDPv6 error handler can update socket's dst cache, but it can happen before the update in the end of udpv6_sendmsg(), preventing getting the new dst cache on the next udpv6_sendmsg() calls. In order to fix it, save dst in a connected socket only if the current socket's dst cache is invalid. The previous patch prepared ip6_sk_dst_lookup_flow() to do that with the new argument, and this patch enables it in udpv6_sendmsg(). Fixes: 33c162a980fe ("ipv6: datagram: Update dst cache of a connected datagram sk during pmtu update") Fixes: 45e4fd26683c ("ipv6: Only create RTF_CACHE routes after encountering pmtu exception") Signed-off-by: Alexey Kodanev Signed-off-by: David S. Miller --- net/ipv6/udp.c | 21 ++------------------- 1 file changed, 2 insertions(+), 19 deletions(-) diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 94861abbea60..4ec76a87aeb8 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1308,7 +1308,7 @@ do_udp_sendmsg: fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel); - dst = ip6_sk_dst_lookup_flow(sk, &fl6, final_p, false); + dst = ip6_sk_dst_lookup_flow(sk, &fl6, final_p, connected); if (IS_ERR(dst)) { err = PTR_ERR(dst); dst = NULL; @@ -1333,7 +1333,7 @@ back_from_confirm: err = PTR_ERR(skb); if (!IS_ERR_OR_NULL(skb)) err = udp_v6_send_skb(skb, &fl6); - goto release_dst; + goto out; } lock_sock(sk); @@ -1367,23 +1367,6 @@ do_append_data: err = np->recverr ? net_xmit_errno(err) : 0; release_sock(sk); -release_dst: - if (dst) { - if (connected) { - ip6_dst_store(sk, dst, - ipv6_addr_equal(&fl6.daddr, &sk->sk_v6_daddr) ? - &sk->sk_v6_daddr : NULL, -#ifdef CONFIG_IPV6_SUBTREES - ipv6_addr_equal(&fl6.saddr, &np->saddr) ? - &np->saddr : -#endif - NULL); - } else { - dst_release(dst); - } - dst = NULL; - } - out: dst_release(dst); fl6_sock_release(flowlabel); -- 2.30.2