Commit 2beb6d29 authored Dec 11, 2019 by Hangbin Liu Committed by Jakub Kicinski Dec 13, 2019

ipv6/addrconf: only check invalid header values when NETLINK_F_STRICT_CHK is set

In commit 4b1373de ("net: ipv6: addr: perform strict checks also for
doit handlers") we add strict check for inet6_rtm_getaddr(). But we did
the invalid header values check before checking if NETLINK_F_STRICT_CHK
is set. This may break backwards compatibility if user already set the
ifm->ifa_prefixlen, ifm->ifa_flags, ifm->ifa_scope in their netlink code.

I didn't move the nlmsg_len check because I thought it's a valid check.

Reported-by: Jianlin Shi <jishi@redhat.com>
Fixes: 4b1373de ("net: ipv6: addr: perform strict checks also for doit handlers")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

parent 03b06e3f

net/ipv6/addrconf.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -5231,16 +5231,16 @@ static int inet6_rtm_valid_getaddr_req(struct sk_buff *skb,
		return -EINVAL;
		}

		if (!netlink_strict_get_check(skb))
		return nlmsg_parse_deprecated(nlh, sizeof(*ifm), tb, IFA_MAX,
		ifa_ipv6_policy, extack);

		ifm = nlmsg_data(nlh);
		if (ifm->ifa_prefixlen \|\| ifm->ifa_flags \|\| ifm->ifa_scope) {
		NL_SET_ERR_MSG_MOD(extack, "Invalid values in header for get address request");
		return -EINVAL;
		}

		if (!netlink_strict_get_check(skb))
		return nlmsg_parse_deprecated(nlh, sizeof(*ifm), tb, IFA_MAX,
		ifa_ipv6_policy, extack);

		err = nlmsg_parse_deprecated_strict(nlh, sizeof(*ifm), tb, IFA_MAX,
		ifa_ipv6_policy, extack);
		if (err)

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