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* [PATCH] net/xfrm: Fix lookups for states with spi == 0
@ 2018-05-02  2:02 Dmitry Safonov
  2018-05-02  9:11 ` Herbert Xu
  0 siblings, 1 reply; 4+ messages in thread
From: Dmitry Safonov @ 2018-05-02  2:02 UTC (permalink / raw)
  To: linux-kernel
  Cc: 0x7f454c46, Dmitry Safonov, Steffen Klassert, Herbert Xu,
	David S. Miller, netdev

It seems to be a valid use case to add xfrm state without
Security Parameter Indexes (SPI) value associated:
ip xfrm state add src $src dst $dst proto $proto mode $mode sel src $src dst $dst $algo

The bad thing is that it's currently impossible to get/delete the state
without SPI: __xfrm_state_insert() obviously doesn't add hash for zero
SPI in xfrm.state_byspi, and xfrm_user_state_lookup() will fail as
xfrm_state_lookup() does lookups by hash.

It also isn't possible to workaround from userspace as
xfrm_id_proto_match() will be always true for ah/esp/comp protos.

So, don't try looking up by hash if SPI == 0.

Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 net/xfrm/xfrm_user.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 080035f056d9..6b38503255c8 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -681,7 +681,7 @@ static struct xfrm_state *xfrm_user_state_lookup(struct net *net,
 	int err;
 	u32 mark = xfrm_mark_get(attrs, &m);
 
-	if (xfrm_id_proto_match(p->proto, IPSEC_PROTO_ANY)) {
+	if (xfrm_id_proto_match(p->proto, IPSEC_PROTO_ANY) && p->spi) {
 		err = -ESRCH;
 		x = xfrm_state_lookup(net, mark, &p->daddr, p->spi, p->proto, p->family);
 	} else {
-- 
2.13.6

^ permalink raw reply related	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2018-05-03  5:40 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-05-02  2:02 [PATCH] net/xfrm: Fix lookups for states with spi == 0 Dmitry Safonov
2018-05-02  9:11 ` Herbert Xu
2018-05-02 12:41   ` Dmitry Safonov
2018-05-03  5:40     ` Herbert Xu

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