[PATCH 4.9 040/223] xfrm: fix sa selector validation

[Greg Kroah-Hartman]

[ Upstream commit b8d6d0079757cbd1b69724cfd1c08e2171c68cee ]

After commit b38ff4075a80, the following command does not work anymore:
$ ip xfrm state add src 10.125.0.2 dst 10.125.0.1 proto esp spi 34 reqid 1 \
  mode tunnel enc 'cbc(aes)' 0xb0abdba8b782ad9d364ec81e3a7d82a1 auth-trunc \
  'hmac(sha1)' 0xe26609ebd00acb6a4d51fca13e49ea78a72c73e6 96 flag align4

In fact, the selector is not mandatory, allow the user to provide an empty
selector.

Fixes: b38ff4075a80 ("xfrm: Fix xfrm sel prefix length validation")
CC: Anirudh Gupta <anirudh.gupta@xxxxxxxxxx>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
Acked-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/xfrm/xfrm_user.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index df4b7fc721f6..f3e9d500fa5a 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -166,6 +166,9 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
 	}
 
 	switch (p->sel.family) {
+	case AF_UNSPEC:
+		break;
+
 	case AF_INET:
 		if (p->sel.prefixlen_d > 32 || p->sel.prefixlen_s > 32)
 			goto out;
-- 
2.20.1