| Message ID | 1526673338-486-1-git-send-email-wang6495@umn.edu (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Herbert Xu |
| Headers | show |
On Fri, May 18, 2018 at 02:55:35PM -0500, Wenwen Wang wrote: > 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 <wang6495@umn.edu> Patch applied. Thanks.
diff --git a/drivers/crypto/chelsio/chtls/chtls_main.c b/drivers/crypto/chelsio/chtls/chtls_main.c index 007c45c..39aab05 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((char *)crypto_info + sizeof(*crypto_info), + optval + sizeof(*crypto_info), + sizeof(struct tls12_crypto_info_aes_gcm_128) + - sizeof(*crypto_info)); if (rc) { rc = -EFAULT;
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 <wang6495@umn.edu> --- drivers/crypto/chelsio/chtls/chtls_main.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)