linux-kernel - [PATCH 3.16.y-ckt 125/180] crypto: af_alg - Forbid bind(2) when nokey child sockets are present

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Message-Id: <1454538786-12215-126-git-send-email-luis.henriques@canonical.com>
Date:	Wed,  3 Feb 2016 22:32:11 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 125/180] crypto: af_alg - Forbid bind(2) when nokey child sockets are present

3.16.7-ckt24 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Herbert Xu <herbert@...dor.apana.org.au>

commit a6a48c565f6f112c6983e2a02b1602189ed6e26e upstream.

This patch forbids the calling of bind(2) when there are child
sockets created by accept(2) in existence, even if they are created
on the nokey path.

This is needed as those child sockets have references to the tfm
object which bind(2) will destroy.

Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 crypto/af_alg.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index d86ef339d8cb..30c1ae491fd4 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -130,19 +130,16 @@ EXPORT_SYMBOL_GPL(af_alg_release);
 void af_alg_release_parent(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
-	bool last;
+	unsigned int nokey = ask->nokey_refcnt;
+	bool last = nokey && !ask->refcnt;
 
 	sk = ask->parent;
-
-	if (ask->nokey_refcnt && !ask->refcnt) {
-		sock_put(sk);
-		return;
-	}
-
 	ask = alg_sk(sk);
 
 	lock_sock(sk);
-	last = !--ask->refcnt;
+	ask->nokey_refcnt -= nokey;
+	if (!last)
+		last = !--ask->refcnt;
 	release_sock(sk);
 
 	if (last)
@@ -185,7 +182,7 @@ static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 
 	err = -EBUSY;
 	lock_sock(sk);
-	if (ask->refcnt)
+	if (ask->refcnt | ask->nokey_refcnt)
 		goto unlock;
 
 	swap(ask->type, type);
@@ -296,6 +293,7 @@ int af_alg_accept(struct sock *sk, struct socket *newsock)
 
 	if (nokey || !ask->refcnt++)
 		sock_hold(sk);
+	ask->nokey_refcnt += nokey;
 	alg_sk(sk2)->parent = sk;
 	alg_sk(sk2)->type = type;
 	alg_sk(sk2)->nokey_refcnt = nokey;