tls: Avoid copying crypto_info again after cipher_type check.

commit 196c31b4b5 upstream.

Avoid copying crypto_info again after cipher_type check
to avoid a TOCTOU exploits.
The temporary array on the stack is removed as we don't really need it

Fixes: 3c4d755915 ('tls: kernel TLS support')
Signed-off-by: Ilya Lesokhin <ilyal@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 4.14: Preserve changes made by earlier backports of
 "tls: return -EBUSY if crypto_info is already set" and "tls: zero the
 crypto information from tls_context before freeing"]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ilya Lesokhin 2017-11-13 10:22:48 +02:00 committed by Greg Kroah-Hartman
parent 797b8bb47f
commit 93f16446c8

View file

@ -381,7 +381,7 @@ static int tls_getsockopt(struct sock *sk, int level, int optname,
static int do_tls_setsockopt_tx(struct sock *sk, char __user *optval,
unsigned int optlen)
{
struct tls_crypto_info *crypto_info, tmp_crypto_info;
struct tls_crypto_info *crypto_info;
struct tls_context *ctx = tls_get_ctx(sk);
int rc = 0;
int tx_conf;
@ -391,38 +391,33 @@ static int do_tls_setsockopt_tx(struct sock *sk, char __user *optval,
goto out;
}
rc = copy_from_user(&tmp_crypto_info, optval, sizeof(*crypto_info));
if (rc) {
rc = -EFAULT;
goto out;
}
/* check version */
if (tmp_crypto_info.version != TLS_1_2_VERSION) {
rc = -ENOTSUPP;
goto out;
}
/* get user crypto info */
crypto_info = &ctx->crypto_send.info;
/* Currently we don't support set crypto info more than one time */
if (TLS_CRYPTO_INFO_READY(crypto_info)) {
rc = -EBUSY;
goto out;
}
switch (tmp_crypto_info.cipher_type) {
rc = copy_from_user(crypto_info, optval, sizeof(*crypto_info));
if (rc) {
rc = -EFAULT;
goto out;
}
/* check version */
if (crypto_info->version != TLS_1_2_VERSION) {
rc = -ENOTSUPP;
goto err_crypto_info;
}
switch (crypto_info->cipher_type) {
case TLS_CIPHER_AES_GCM_128: {
if (optlen != sizeof(struct tls12_crypto_info_aes_gcm_128)) {
rc = -EINVAL;
goto err_crypto_info;
}
rc = copy_from_user(
crypto_info,
optval,
sizeof(struct tls12_crypto_info_aes_gcm_128));
rc = copy_from_user(crypto_info + 1, optval + sizeof(*crypto_info),
optlen - sizeof(*crypto_info));
if (rc) {
rc = -EFAULT;
goto err_crypto_info;