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crypto: af_alg - whitelist mask and type

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The user space interface allows specifying the type and mask field used
to allocate the cipher. Only a subset of the possible flags are intended
for user space. Therefore, white-list the allowed flags.

In case the user space caller uses at least one non-allowed flag, EINVAL
is returned.

Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stephan Mueller 2018-01-02 08:55:25 +01:00 committed by Herbert Xu
parent da1729ce48
commit bb30b8848c
1 changed files with 6 additions and 4 deletions
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10
crypto/af_alg.c
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@ -150,7 +150,7 @@ EXPORT_SYMBOL_GPL(af_alg_release_parent);
static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{ {
const u32 forbidden = CRYPTO_ALG_INTERNAL; const u32 allowed = CRYPTO_ALG_KERN_DRIVER_ONLY;
struct sock *sk = sock->sk; struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk); struct alg_sock *ask = alg_sk(sk);
struct sockaddr_alg *sa = (void *)uaddr; struct sockaddr_alg *sa = (void *)uaddr;
@ -158,6 +158,10 @@ static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
void *private; void *private;
int err; int err;
/* If caller uses non-allowed flag, return error. */
if ((sa->salg_feat & ~allowed) || (sa->salg_mask & ~allowed))
return -EINVAL;
if (sock->state == SS_CONNECTED) if (sock->state == SS_CONNECTED)
return -EINVAL; return -EINVAL;
@ -176,9 +180,7 @@ static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
if (IS_ERR(type)) if (IS_ERR(type))
return PTR_ERR(type); return PTR_ERR(type);
private = type->bind(sa->salg_name, private = type->bind(sa->salg_name, sa->salg_feat, sa->salg_mask);
sa->salg_feat & ~forbidden,
sa->salg_mask & ~forbidden);
if (IS_ERR(private)) { if (IS_ERR(private)) {
module_put(type->owner); module_put(type->owner);
return PTR_ERR(private); return PTR_ERR(private);