netdev - [net-next v1] net/ipv6: allow any source address for sendmsg pktinfo with ip_nonlocal

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Date:   Wed, 25 Jul 2018 13:19:13 +0200
From:   Vincent Bernat <vincent@...nat.im>
To:     "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netdev@...r.kernel.org, Tom Herbert <tom@...bertland.com>
Cc:     Vincent Bernat <vincent@...nat.im>
Subject: [net-next v1] net/ipv6: allow any source address for sendmsg pktinfo with ip_nonlocal_bind

When freebind feature is set of an IPv6 socket, any source address can
be used when sending UDP datagrams using IPv6 PKTINFO ancillary
message. Global non-local bind feature was added in commit
35a256fee52c ("ipv6: Nonlocal bind") for IPv6. This commit also allows
IPv6 source address spoofing when non-local bind feature is enabled.

Signed-off-by: Vincent Bernat <vincent@...nat.im>
---
 net/ipv6/datagram.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 201306b9b5ea..c46936563b15 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -800,7 +800,8 @@ int ip6_datagram_send_ctl(struct net *net, struct sock *sk,
 
 			if (addr_type != IPV6_ADDR_ANY) {
 				int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;
-				if (!(inet_sk(sk)->freebind || inet_sk(sk)->transparent) &&
+				if (!(net->ipv6.sysctl.ip_nonlocal_bind ||
+				      inet_sk(sk)->freebind || inet_sk(sk)->transparent) &&
 				    !ipv6_chk_addr_and_flags(net, &src_info->ipi6_addr,
 							     dev, !strict, 0,
 							     IFA_F_TENTATIVE) &&
-- 
2.18.0