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authorLinus Lüssing <linus.luessing@c0d3.blue>2021-04-25 17:27:35 +0200
committerDavid S. Miller <davem@davemloft.net>2021-04-27 14:02:06 -0700
commit99014088156cd78867d19514a0bc771c4b86b93b (patch)
tree3e196ee651ebc5b4bc70b367c916152ab2c52547 /include/net
parent6d72e7c767acbbdd44ebc7d89c6690b405b32b57 (diff)
net: bridge: mcast: fix broken length + header check for MRDv6 Adv.
The IPv6 Multicast Router Advertisements parsing has the following two issues: For one thing, ICMPv6 MRD Advertisements are smaller than ICMPv6 MLD messages (ICMPv6 MRD Adv.: 8 bytes vs. ICMPv6 MLDv1/2: >= 24 bytes, assuming MLDv2 Reports with at least one multicast address entry). When ipv6_mc_check_mld_msg() tries to parse an Multicast Router Advertisement its MLD length check will fail - and it will wrongly return -EINVAL, even if we have a valid MRD Advertisement. With the returned -EINVAL the bridge code will assume a broken packet and will wrongly discard it, potentially leading to multicast packet loss towards multicast routers. The second issue is the MRD header parsing in br_ip6_multicast_mrd_rcv(): It wrongly checks for an ICMPv6 header immediately after the IPv6 header (IPv6 next header type). However according to RFC4286, section 2 all MRD messages contain a Router Alert option (just like MLD). So instead there is an IPv6 Hop-by-Hop option for the Router Alert between the IPv6 and ICMPv6 header, again leading to the bridge wrongly discarding Multicast Router Advertisements. To fix these two issues, introduce a new return value -ENODATA to ipv6_mc_check_mld() to indicate a valid ICMPv6 packet with a hop-by-hop option which is not an MLD but potentially an MRD packet. This also simplifies further parsing in the bridge code, as ipv6_mc_check_mld() already fully checks the ICMPv6 header and hop-by-hop option. These issues were found and fixed with the help of the mrdisc tool (https://github.com/troglobit/mrdisc). Fixes: 4b3087c7e37f ("bridge: Snoop Multicast Router Advertisements") Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/addrconf.h1
1 files changed, 0 insertions, 1 deletions
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 18f783dcd55f..78ea3e332688 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -233,7 +233,6 @@ void ipv6_mc_unmap(struct inet6_dev *idev);
void ipv6_mc_remap(struct inet6_dev *idev);
void ipv6_mc_init_dev(struct inet6_dev *idev);
void ipv6_mc_destroy_dev(struct inet6_dev *idev);
-int ipv6_mc_check_icmpv6(struct sk_buff *skb);
int ipv6_mc_check_mld(struct sk_buff *skb);
void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp);