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Date: Fri, 14 Apr 2017 20:22:43 +0200 From: Florian Westphal <fw@...len.de> To: <netdev@...r.kernel.org> Cc: Florian Westphal <fw@...len.de> Subject: [PATCH net] 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 <edumazet@...gle.com> Signed-off-by: Florian Westphal <fw@...len.de> --- net/ipv6/ip6_input.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) 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 -- 2.10.2
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