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authorHerbert Xu <herbert@gondor.apana.org.au>2015-12-30 11:47:53 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-17 12:31:02 -0800
commit7509864bb2ec8a4dfbda52a9bda577ecdcb6b2c4 (patch)
tree613f23037413bd45d3741919a528c8eaadc06e8a
parentb238717c0bb4606e2e36fc0de745306b0c900d83 (diff)
downloadlwn-7509864bb2ec8a4dfbda52a9bda577ecdcb6b2c4.tar.gz
lwn-7509864bb2ec8a4dfbda52a9bda577ecdcb6b2c4.zip
crypto: af_alg - Disallow bind/setkey/... after accept(2)
commit c840ac6af3f8713a71b4d2363419145760bd6044 upstream. Each af_alg parent socket obtained by socket(2) corresponds to a tfm object once bind(2) has succeeded. An accept(2) call on that parent socket creates a context which then uses the tfm object. Therefore as long as any child sockets created by accept(2) exist the parent socket must not be modified or freed. This patch guarantees this by using locks and a reference count on the parent socket. Any attempt to modify the parent socket will fail with EBUSY. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--crypto/af_alg.c35
-rw-r--r--include/crypto/if_alg.h8
2 files changed, 35 insertions, 8 deletions
diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index a8e7aa3e257b..7b5b5926c767 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -125,6 +125,23 @@ int af_alg_release(struct socket *sock)
}
EXPORT_SYMBOL_GPL(af_alg_release);
+void af_alg_release_parent(struct sock *sk)
+{
+ struct alg_sock *ask = alg_sk(sk);
+ bool last;
+
+ sk = ask->parent;
+ ask = alg_sk(sk);
+
+ lock_sock(sk);
+ last = !--ask->refcnt;
+ release_sock(sk);
+
+ if (last)
+ sock_put(sk);
+}
+EXPORT_SYMBOL_GPL(af_alg_release_parent);
+
static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
const u32 forbidden = CRYPTO_ALG_INTERNAL;
@@ -133,6 +150,7 @@ static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
struct sockaddr_alg *sa = (void *)uaddr;
const struct af_alg_type *type;
void *private;
+ int err;
if (sock->state == SS_CONNECTED)
return -EINVAL;
@@ -160,16 +178,22 @@ static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
return PTR_ERR(private);
}
+ err = -EBUSY;
lock_sock(sk);
+ if (ask->refcnt)
+ goto unlock;
swap(ask->type, type);
swap(ask->private, private);
+ err = 0;
+
+unlock:
release_sock(sk);
alg_do_release(type, private);
- return 0;
+ return err;
}
static int alg_setkey(struct sock *sk, char __user *ukey,
@@ -202,11 +226,15 @@ static int alg_setsockopt(struct socket *sock, int level, int optname,
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
const struct af_alg_type *type;
- int err = -ENOPROTOOPT;
+ int err = -EBUSY;
lock_sock(sk);
+ if (ask->refcnt)
+ goto unlock;
+
type = ask->type;
+ err = -ENOPROTOOPT;
if (level != SOL_ALG || !type)
goto unlock;
@@ -264,7 +292,8 @@ int af_alg_accept(struct sock *sk, struct socket *newsock)
sk2->sk_family = PF_ALG;
- sock_hold(sk);
+ if (!ask->refcnt++)
+ sock_hold(sk);
alg_sk(sk2)->parent = sk;
alg_sk(sk2)->type = type;
diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index 018afb264ac2..589716f2ee8a 100644
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -30,6 +30,8 @@ struct alg_sock {
struct sock *parent;
+ unsigned int refcnt;
+
const struct af_alg_type *type;
void *private;
};
@@ -67,6 +69,7 @@ int af_alg_register_type(const struct af_alg_type *type);
int af_alg_unregister_type(const struct af_alg_type *type);
int af_alg_release(struct socket *sock);
+void af_alg_release_parent(struct sock *sk);
int af_alg_accept(struct sock *sk, struct socket *newsock);
int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len);
@@ -83,11 +86,6 @@ static inline struct alg_sock *alg_sk(struct sock *sk)
return (struct alg_sock *)sk;
}
-static inline void af_alg_release_parent(struct sock *sk)
-{
- sock_put(alg_sk(sk)->parent);
-}
-
static inline void af_alg_init_completion(struct af_alg_completion *completion)
{
init_completion(&completion->completion);