115 lines
3.8 KiB
Diff
115 lines
3.8 KiB
Diff
From c149dd0767f32789e391280cb1eb06b7eb7c6bce Mon Sep 17 00:00:00 2001
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From: Alexander Sosedkin <asosedkin@redhat.com>
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Date: Tue, 9 Aug 2022 16:05:53 +0200
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Subject: [PATCH 1/2] auth/rsa: side-step potential side-channel
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Remove branching that depends on secret data.
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Signed-off-by: Alexander Sosedkin <asosedkin@redhat.com>
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Signed-off-by: Hubert Kario <hkario@redhat.com>
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Tested-by: Hubert Kario <hkario@redhat.com>
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---
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lib/auth/rsa.c | 10 ----------
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1 file changed, 10 deletions(-)
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diff --git a/lib/auth/rsa.c b/lib/auth/rsa.c
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index 8108ee841d..6b158bacb2 100644
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--- a/lib/auth/rsa.c
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+++ b/lib/auth/rsa.c
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@@ -155,7 +155,6 @@ static int
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proc_rsa_client_kx(gnutls_session_t session, uint8_t * data,
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size_t _data_size)
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{
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- const char attack_error[] = "auth_rsa: Possible PKCS #1 attack\n";
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gnutls_datum_t ciphertext;
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int ret, dsize;
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ssize_t data_size = _data_size;
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@@ -235,15 +234,6 @@ proc_rsa_client_kx(gnutls_session_t session, uint8_t * data,
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ok &= CONSTCHECK_NOT_EQUAL(check_ver_min, 0) &
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CONSTCHECK_EQUAL(session->key.key.data[1], ver_min);
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- if (ok) {
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- /* call logging function unconditionally so all branches are
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- * indistinguishable for timing and cache access when debug
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- * logging is disabled */
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- _gnutls_no_log("%s", attack_error);
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- } else {
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- _gnutls_debug_log("%s", attack_error);
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- }
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-
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/* This is here to avoid the version check attack
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* discussed above.
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*/
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--
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2.39.1
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From 7c963102ec2119eecc1789b993aabe5edfd75f3b Mon Sep 17 00:00:00 2001
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From: Hubert Kario <hkario@redhat.com>
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Date: Wed, 8 Feb 2023 14:32:09 +0100
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Subject: [PATCH 2/2] rsa: remove dead code
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since the `ok` variable isn't used any more, we can remove all code
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used to calculate it
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Signed-off-by: Hubert Kario <hkario@redhat.com>
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---
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lib/auth/rsa.c | 20 +++-----------------
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1 file changed, 3 insertions(+), 17 deletions(-)
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diff --git a/lib/auth/rsa.c b/lib/auth/rsa.c
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index 6b158bacb2..858701fe6e 100644
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--- a/lib/auth/rsa.c
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+++ b/lib/auth/rsa.c
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@@ -159,8 +159,6 @@ proc_rsa_client_kx(gnutls_session_t session, uint8_t * data,
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int ret, dsize;
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ssize_t data_size = _data_size;
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volatile uint8_t ver_maj, ver_min;
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- volatile uint8_t check_ver_min;
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- volatile uint32_t ok;
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#ifdef ENABLE_SSL3
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if (get_num_version(session) == GNUTLS_SSL3) {
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@@ -186,7 +184,6 @@ proc_rsa_client_kx(gnutls_session_t session, uint8_t * data,
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ver_maj = _gnutls_get_adv_version_major(session);
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ver_min = _gnutls_get_adv_version_minor(session);
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- check_ver_min = (session->internals.allow_wrong_pms == 0);
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session->key.key.data = gnutls_malloc(GNUTLS_MASTER_SIZE);
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if (session->key.key.data == NULL) {
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@@ -205,10 +202,9 @@ proc_rsa_client_kx(gnutls_session_t session, uint8_t * data,
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return ret;
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}
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- ret =
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- gnutls_privkey_decrypt_data2(session->internals.selected_key,
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- 0, &ciphertext, session->key.key.data,
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- session->key.key.size);
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+ gnutls_privkey_decrypt_data2(session->internals.selected_key,
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+ 0, &ciphertext, session->key.key.data,
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+ session->key.key.size);
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/* After this point, any conditional on failure that cause differences
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* in execution may create a timing or cache access pattern side
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* channel that can be used as an oracle, so treat very carefully */
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@@ -224,16 +220,6 @@ proc_rsa_client_kx(gnutls_session_t session, uint8_t * data,
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* Vlastimil Klima, Ondej Pokorny and Tomas Rosa.
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*/
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- /* ok is 0 in case of error and 1 in case of success. */
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-
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- /* if ret < 0 */
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- ok = CONSTCHECK_EQUAL(ret, 0);
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- /* session->key.key.data[0] must equal ver_maj */
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- ok &= CONSTCHECK_EQUAL(session->key.key.data[0], ver_maj);
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- /* if check_ver_min then session->key.key.data[1] must equal ver_min */
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- ok &= CONSTCHECK_NOT_EQUAL(check_ver_min, 0) &
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- CONSTCHECK_EQUAL(session->key.key.data[1], ver_min);
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-
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/* This is here to avoid the version check attack
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* discussed above.
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*/
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--
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2.39.1
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