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CVE-2023-2283:pki_crypto: Fix possible authentication bypass

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The return value is changed by the call to pki_key_check_hash_compatible
causing the possibility of returning SSH_OK if memory allocation error
happens later in the function.

The assignment of SSH_ERROR if the verification fails is no longer needed,
because the value of the variable is already SSH_ERROR.

Signed-off-by: Norbert Pocs <npocs@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This commit is contained in:
Norbert Pocs
2023-04-24 11:51:36 +02:00
committed by Andreas Schneider
parent dc1254d53e
commit e8dfbb85a2
1 changed files with 18 additions and 14 deletions
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32
src/pki_crypto.c
View File

@@ -3175,8 +3175,12 @@ int pki_verify_data_signature(ssh_signature signature,
unsigned char *raw_sig_data = NULL;
unsigned int raw_sig_len;
/* Function return code
* Do not change this variable throughout the function until the signature
* is successfully verified!
*/
int rc = SSH_ERROR;
int evp_rc;
int ok;
if (pubkey == NULL || ssh_key_is_private(pubkey) || input == NULL ||
signature == NULL || (signature->raw_sig == NULL
@@ -3191,8 +3195,8 @@ int pki_verify_data_signature(ssh_signature signature,
}
/* Check if public key and hash type are compatible */
rc = pki_key_check_hash_compatible(pubkey, signature->hash_type);
if (rc != SSH_OK) {
ok = pki_key_check_hash_compatible(pubkey, signature->hash_type);
if (ok != SSH_OK) {
return SSH_ERROR;
}
@@ -3237,8 +3241,8 @@ int pki_verify_data_signature(ssh_signature signature,
}
/* Verify the signature */
evp_rc = EVP_DigestVerifyInit(ctx, NULL, md, NULL, pkey);
if (evp_rc != 1){
ok = EVP_DigestVerifyInit(ctx, NULL, md, NULL, pkey);
if (ok != 1){
SSH_LOG(SSH_LOG_TRACE,
"EVP_DigestVerifyInit() failed: %s",
ERR_error_string(ERR_get_error(), NULL));
@@ -3246,28 +3250,28 @@ int pki_verify_data_signature(ssh_signature signature,
}
#ifdef HAVE_OPENSSL_EVP_DIGESTVERIFY
evp_rc = EVP_DigestVerify(ctx, raw_sig_data, raw_sig_len, input, input_len);
ok = EVP_DigestVerify(ctx, raw_sig_data, raw_sig_len, input, input_len);
#else
evp_rc = EVP_DigestVerifyUpdate(ctx, input, input_len);
if (evp_rc != 1) {
ok = EVP_DigestVerifyUpdate(ctx, input, input_len);
if (ok != 1) {
SSH_LOG(SSH_LOG_TRACE,
"EVP_DigestVerifyUpdate() failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto out;
}
evp_rc = EVP_DigestVerifyFinal(ctx, raw_sig_data, raw_sig_len);
ok = EVP_DigestVerifyFinal(ctx, raw_sig_data, raw_sig_len);
#endif
if (evp_rc == 1) {
SSH_LOG(SSH_LOG_TRACE, "Signature valid");
rc = SSH_OK;
} else {
if (ok != 1) {
SSH_LOG(SSH_LOG_TRACE,
"Signature invalid: %s",
ERR_error_string(ERR_get_error(), NULL));
rc = SSH_ERROR;
goto out;
}
SSH_LOG(SSH_LOG_TRACE, "Signature valid");
rc = SSH_OK;
out:
if (ctx != NULL) {
EVP_MD_CTX_free(ctx);