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tls: Avoid copying crypto_info again after cipher_type check. 

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>
This commit is contained in:
Ilya Lesokhin 2017-11-13 10:22:48 +02:00 committed by David S. Miller
parent 213ef6e7c9
commit 196c31b4b5
1 changed files with 12 additions and 17 deletions
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29
net/tls/tls_main.c
View File

@ -355,7 +355,7 @@ 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;
@ -365,36 +365,31 @@ 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));
crypto_info = &ctx->crypto_send;
/* Currently we don't support set crypto info more than one time */
if (TLS_CRYPTO_INFO_READY(crypto_info))
goto out;
rc = copy_from_user(crypto_info, optval, sizeof(*crypto_info));
if (rc) {
rc = -EFAULT;
goto out;
}
/* check version */
if (tmp_crypto_info.version != TLS_1_2_VERSION) {
if (crypto_info->version != TLS_1_2_VERSION) {
rc = -ENOTSUPP;
goto out;
goto err_crypto_info;
}
/* get user crypto info */
crypto_info = &ctx->crypto_send;
/* Currently we don't support set crypto info more than one time */
if (TLS_CRYPTO_INFO_READY(crypto_info))
goto out;
switch (tmp_crypto_info.cipher_type) {
switch (crypto_info->cipher_type) {
case TLS_CIPHER_AES_GCM_128: {
if (optlen != sizeof(struct tls12_crypto_info_aes_gcm_128)) {
rc = -EINVAL;
goto out;
}
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;