From 80a6ce8ddb02477cd724cd5b2944791aaddb702a Mon Sep 17 00:00:00 2001 From: Alexander Sosedkin Date: Tue, 9 Aug 2022 16:05:53 +0200 Subject: [PATCH] auth/rsa: side-step potential side-channel Signed-off-by: Alexander Sosedkin Signed-off-by: Hubert Kario Tested-by: Hubert Kario Upstream-Status: Backport [https://gitlab.com/gnutls/gnutls/-/commit/80a6ce8ddb02477cd724cd5b2944791aaddb702a https://gitlab.com/gnutls/gnutls/-/commit/4b7ff428291c7ed77c6d2635577c83a43bbae558] CVE: CVE-2023-0361 Signed-off-by: Vivek Kumbhar --- lib/auth/rsa.c | 30 +++--------------------------- 1 file changed, 3 insertions(+), 27 deletions(-) diff --git a/lib/auth/rsa.c b/lib/auth/rsa.c index 8108ee8..858701f 100644 --- a/lib/auth/rsa.c +++ b/lib/auth/rsa.c @@ -155,13 +155,10 @@ static int proc_rsa_client_kx(gnutls_session_t session, uint8_t * data, size_t _data_size) { - const char attack_error[] = "auth_rsa: Possible PKCS #1 attack\n"; gnutls_datum_t ciphertext; int ret, dsize; ssize_t data_size = _data_size; volatile uint8_t ver_maj, ver_min; - volatile uint8_t check_ver_min; - volatile uint32_t ok; #ifdef ENABLE_SSL3 if (get_num_version(session) == GNUTLS_SSL3) { @@ -187,7 +184,6 @@ proc_rsa_client_kx(gnutls_session_t session, uint8_t * data, ver_maj = _gnutls_get_adv_version_major(session); ver_min = _gnutls_get_adv_version_minor(session); - check_ver_min = (session->internals.allow_wrong_pms == 0); session->key.key.data = gnutls_malloc(GNUTLS_MASTER_SIZE); if (session->key.key.data == NULL) { @@ -206,10 +202,9 @@ proc_rsa_client_kx(gnutls_session_t session, uint8_t * data, return ret; } - ret = - gnutls_privkey_decrypt_data2(session->internals.selected_key, - 0, &ciphertext, session->key.key.data, - session->key.key.size); + gnutls_privkey_decrypt_data2(session->internals.selected_key, + 0, &ciphertext, session->key.key.data, + session->key.key.size); /* After this point, any conditional on failure that cause differences * in execution may create a timing or cache access pattern side * channel that can be used as an oracle, so treat very carefully */ @@ -225,25 +220,6 @@ proc_rsa_client_kx(gnutls_session_t session, uint8_t * data, * Vlastimil Klima, Ondej Pokorny and Tomas Rosa. */ - /* ok is 0 in case of error and 1 in case of success. */ - - /* if ret < 0 */ - ok = CONSTCHECK_EQUAL(ret, 0); - /* session->key.key.data[0] must equal ver_maj */ - ok &= CONSTCHECK_EQUAL(session->key.key.data[0], ver_maj); - /* if check_ver_min then session->key.key.data[1] must equal ver_min */ - ok &= CONSTCHECK_NOT_EQUAL(check_ver_min, 0) & - CONSTCHECK_EQUAL(session->key.key.data[1], ver_min); - - if (ok) { - /* call logging function unconditionally so all branches are - * indistinguishable for timing and cache access when debug - * logging is disabled */ - _gnutls_no_log("%s", attack_error); - } else { - _gnutls_debug_log("%s", attack_error); - } - /* This is here to avoid the version check attack * discussed above. */ -- 2.25.1