In do_chtls_setsockopt(), the tls crypto info is first copied from the
poiner 'optval' in userspace and saved to 'tmp_crypto_info'. Then the
'version' of the crypto info is checked. If the version is not as expected,
i.e., TLS_1_2_VERSION, error code -ENOTSUPP is returned to indicate that
the provided crypto info is not supported yet. Then, the 'cipher_type'
field of the 'tmp_crypto_info' is also checked to see if it is
TLS_CIPHER_AES_GCM_128. If it is, the whole struct of
tls12_crypto_info_aes_gcm_128 is copied from the pointer 'optval' and then
the function chtls_setkey() is invoked to set the key.
Given that the 'optval' pointer resides in userspace, a malicious userspace
process can race to change the data pointed by 'optval' between the two
copies. For example, a user can provide a crypto info with TLS_1_2_VERSION
and TLS_CIPHER_AES_GCM_128. After the first copy, the user can modify the
'version' and the 'cipher_type' fields to any versions and/or cipher types
that are not allowed. This way, the user can bypass the checks, inject
bad data to the kernel, cause chtls_setkey() to set a wrong key or other
issues.
This patch reuses the data copied in the first try so as to ensure these
checks will not be bypassed.
Signed-off-by: Wenwen Wang <[email protected]>
---
drivers/crypto/chelsio/chtls/chtls_main.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/crypto/chelsio/chtls/chtls_main.c b/drivers/crypto/chelsio/chtls/chtls_main.c
index 007c45c..859958a 100644
--- a/drivers/crypto/chelsio/chtls/chtls_main.c
+++ b/drivers/crypto/chelsio/chtls/chtls_main.c
@@ -491,9 +491,13 @@ static int do_chtls_setsockopt(struct sock *sk, int optname,
switch (tmp_crypto_info.cipher_type) {
case TLS_CIPHER_AES_GCM_128: {
- rc = copy_from_user(crypto_info, optval,
- sizeof(struct
- tls12_crypto_info_aes_gcm_128));
+ /* Obtain version and type from previous copy */
+ crypto_info[0] = tmp_crypto_info;
+ /* Now copy the following data */
+ rc = copy_from_user(crypto_info + sizeof(*crypto_info),
+ optval + sizeof(*crypto_info),
+ sizeof(struct tls12_crypto_info_aes_gcm_128)
+ - sizeof(*crypto_info));
if (rc) {
rc = -EFAULT;
--
2.7.4
Hi Wenwen,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on cryptodev/master]
[also build test WARNING on v4.17-rc3 next-20180504]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Wenwen-Wang/crypto-chtls-fix-a-missing-check-bug/20180506-091039
base: https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git master
:::::: branch date: 26 hours ago
:::::: commit date: 26 hours ago
New smatch warnings:
drivers/crypto/chelsio/chtls/chtls_main.c:496 do_chtls_setsockopt() warn: potential pointer math issue ('crypto_info' is a 32 bit pointer)
Old smatch warnings:
drivers/crypto/chelsio/chtls/chtls_main.c:253 chtls_uld_add() error: buffer overflow 'cdev->rspq_skb_cache' 32 <= 32
drivers/crypto/chelsio/chtls/chtls_main.c:350 chtls_recv_packet() error: double free of 'skb'
drivers/crypto/chelsio/chtls/chtls_main.c:390 chtls_recv_rsp() error: double free of 'skb'
drivers/crypto/chelsio/chtls/chtls_main.c:408 chtls_recv() error: double free of 'skb'
# https://github.com/0day-ci/linux/commit/183b5e3e71c75e3149dac2698883f0bd63a89c75
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 183b5e3e71c75e3149dac2698883f0bd63a89c75
vim +496 drivers/crypto/chelsio/chtls/chtls_main.c
a0894394 Atul Gupta 2018-03-31 461
a0894394 Atul Gupta 2018-03-31 462 static int do_chtls_setsockopt(struct sock *sk, int optname,
a0894394 Atul Gupta 2018-03-31 463 char __user *optval, unsigned int optlen)
a0894394 Atul Gupta 2018-03-31 464 {
a0894394 Atul Gupta 2018-03-31 465 struct tls_crypto_info *crypto_info, tmp_crypto_info;
a0894394 Atul Gupta 2018-03-31 466 struct chtls_sock *csk;
a0894394 Atul Gupta 2018-03-31 467 int keylen;
a0894394 Atul Gupta 2018-03-31 468 int rc = 0;
a0894394 Atul Gupta 2018-03-31 469
a0894394 Atul Gupta 2018-03-31 470 csk = rcu_dereference_sk_user_data(sk);
a0894394 Atul Gupta 2018-03-31 471
a0894394 Atul Gupta 2018-03-31 472 if (!optval || optlen < sizeof(*crypto_info)) {
a0894394 Atul Gupta 2018-03-31 473 rc = -EINVAL;
a0894394 Atul Gupta 2018-03-31 474 goto out;
a0894394 Atul Gupta 2018-03-31 475 }
a0894394 Atul Gupta 2018-03-31 476
a0894394 Atul Gupta 2018-03-31 477 rc = copy_from_user(&tmp_crypto_info, optval, sizeof(*crypto_info));
a0894394 Atul Gupta 2018-03-31 478 if (rc) {
a0894394 Atul Gupta 2018-03-31 479 rc = -EFAULT;
a0894394 Atul Gupta 2018-03-31 480 goto out;
a0894394 Atul Gupta 2018-03-31 481 }
a0894394 Atul Gupta 2018-03-31 482
a0894394 Atul Gupta 2018-03-31 483 /* check version */
a0894394 Atul Gupta 2018-03-31 484 if (tmp_crypto_info.version != TLS_1_2_VERSION) {
a0894394 Atul Gupta 2018-03-31 485 rc = -ENOTSUPP;
a0894394 Atul Gupta 2018-03-31 486 goto out;
a0894394 Atul Gupta 2018-03-31 487 }
a0894394 Atul Gupta 2018-03-31 488
a0894394 Atul Gupta 2018-03-31 489 crypto_info = (struct tls_crypto_info *)&csk->tlshws.crypto_info;
a0894394 Atul Gupta 2018-03-31 490
a0894394 Atul Gupta 2018-03-31 491 switch (tmp_crypto_info.cipher_type) {
a0894394 Atul Gupta 2018-03-31 492 case TLS_CIPHER_AES_GCM_128: {
183b5e3e Wenwen Wang 2018-05-05 493 /* Obtain version and type from previous copy */
183b5e3e Wenwen Wang 2018-05-05 494 crypto_info[0] = tmp_crypto_info;
183b5e3e Wenwen Wang 2018-05-05 495 /* Now copy the following data */
183b5e3e Wenwen Wang 2018-05-05 @496 rc = copy_from_user(crypto_info + sizeof(*crypto_info),
183b5e3e Wenwen Wang 2018-05-05 497 optval + sizeof(*crypto_info),
183b5e3e Wenwen Wang 2018-05-05 498 sizeof(struct tls12_crypto_info_aes_gcm_128)
183b5e3e Wenwen Wang 2018-05-05 499 - sizeof(*crypto_info));
a0894394 Atul Gupta 2018-03-31 500
a0894394 Atul Gupta 2018-03-31 501 if (rc) {
a0894394 Atul Gupta 2018-03-31 502 rc = -EFAULT;
a0894394 Atul Gupta 2018-03-31 503 goto out;
a0894394 Atul Gupta 2018-03-31 504 }
a0894394 Atul Gupta 2018-03-31 505
a0894394 Atul Gupta 2018-03-31 506 keylen = TLS_CIPHER_AES_GCM_128_KEY_SIZE;
a0894394 Atul Gupta 2018-03-31 507 rc = chtls_setkey(csk, keylen, optname);
a0894394 Atul Gupta 2018-03-31 508 break;
a0894394 Atul Gupta 2018-03-31 509 }
a0894394 Atul Gupta 2018-03-31 510 default:
a0894394 Atul Gupta 2018-03-31 511 rc = -EINVAL;
a0894394 Atul Gupta 2018-03-31 512 goto out;
a0894394 Atul Gupta 2018-03-31 513 }
a0894394 Atul Gupta 2018-03-31 514 out:
a0894394 Atul Gupta 2018-03-31 515 return rc;
a0894394 Atul Gupta 2018-03-31 516 }
a0894394 Atul Gupta 2018-03-31 517