From d40a4de0be08f005814a4fddac748fe5353208ec Mon Sep 17 00:00:00 2001 From: Brian Haley Date: Mon, 3 May 2010 15:44:27 +0000 Subject: [PATCH] IPv6: fix IPV6_RECVERR handling of locally-generated errors I noticed when I added support for IPV6_DONTFRAG that if you set IPV6_RECVERR and tried to send a UDP packet larger than 64K to an IPv6 destination, you'd correctly get an EMSGSIZE, but reading from MSG_ERRQUEUE returned the incorrect address in the cmsg: struct msghdr: msg_name 0x7fff8f3c96d0 msg_namelen 28 struct sockaddr_in6: sin6_family 10 sin6_port 7639 sin6_flowinfo 0 sin6_addr ::ffff:38.32.0.0 sin6_scope_id 0 ((null)) It should have returned this in my case: struct msghdr: msg_name 0x7fffd866b510 msg_namelen 28 struct sockaddr_in6: sin6_family 10 sin6_port 7639 sin6_flowinfo 0 sin6_addr 2620:0:a09:e000:21f:29ff:fe57:f88b sin6_scope_id 0 ((null)) The problem is that ipv6_recv_error() assumes that if the error wasn't generated by ICMPv6, it's an IPv4 address sitting there, and proceeds to create a v4-mapped address from it. Change ipv6_icmp_error() and ipv6_local_error() to set skb->protocol to htons(ETH_P_IPV6) so that ipv6_recv_error() knows the address sitting right after the extended error is IPv6, else it will incorrectly map the first octet into an IPv4-mapped IPv6 address in the cmsg structure returned in a recvmsg() call to obtain the error. Signed-off-by: Brian Haley -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Signed-off-by: David S. Miller --- net/ipv6/datagram.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c index 622dc7939a1b..61573885e451 100644 --- a/net/ipv6/datagram.c +++ b/net/ipv6/datagram.c @@ -222,6 +222,8 @@ void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err, if (!skb) return; + skb->protocol = htons(ETH_P_IPV6); + serr = SKB_EXT_ERR(skb); serr->ee.ee_errno = err; serr->ee.ee_origin = SO_EE_ORIGIN_ICMP6; @@ -255,6 +257,8 @@ void ipv6_local_error(struct sock *sk, int err, struct flowi *fl, u32 info) if (!skb) return; + skb->protocol = htons(ETH_P_IPV6); + skb_put(skb, sizeof(struct ipv6hdr)); skb_reset_network_header(skb); iph = ipv6_hdr(skb); @@ -319,7 +323,7 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len) sin->sin6_flowinfo = 0; sin->sin6_port = serr->port; sin->sin6_scope_id = 0; - if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6) { + if (skb->protocol == htons(ETH_P_IPV6)) { ipv6_addr_copy(&sin->sin6_addr, (struct in6_addr *)(nh + serr->addr_offset)); if (np->sndflow) @@ -341,7 +345,7 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len) sin->sin6_family = AF_INET6; sin->sin6_flowinfo = 0; sin->sin6_scope_id = 0; - if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6) { + if (skb->protocol == htons(ETH_P_IPV6)) { ipv6_addr_copy(&sin->sin6_addr, &ipv6_hdr(skb)->saddr); if (np->rxopt.all) datagram_recv_ctl(sk, msg, skb); -- 2.20.1