From: Florian Westphal Date: Fri, 14 Apr 2017 18:22:43 +0000 (+0200) Subject: ipv6: drop non loopback packets claiming to originate from ::1 X-Git-Tag: Ubuntu-5.0.0-8.9~5109^2~1 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=0aa8c13eb512823bc4d60397d666a6b6260bb965;p=mirror_ubuntu-disco-kernel.git ipv6: drop non loopback packets claiming to originate from ::1 We lack a saddr check for ::1. This causes security issues e.g. with acls permitting connections from ::1 because of assumption that these originate from local machine. Assuming a source address of ::1 is local seems reasonable. RFC4291 doesn't allow such a source address either, so drop such packets. Reported-by: Eric Dumazet Signed-off-by: Florian Westphal Acked-by: Eric Dumazet Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c index aacfb4bce153..c45b12b4431c 100644 --- a/net/ipv6/ip6_input.c +++ b/net/ipv6/ip6_input.c @@ -122,11 +122,14 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); /* * RFC4291 2.5.3 + * The loopback address must not be used as the source address in IPv6 + * packets that are sent outside of a single node. [..] * A packet received on an interface with a destination address * of loopback must be dropped. */ - if (!(dev->flags & IFF_LOOPBACK) && - ipv6_addr_loopback(&hdr->daddr)) + if ((ipv6_addr_loopback(&hdr->saddr) || + ipv6_addr_loopback(&hdr->daddr)) && + !(dev->flags & IFF_LOOPBACK)) goto err; /* RFC4291 Errata ID: 3480