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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 07:33:14 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 07:33:14 +0000 |
commit | 99db386956013535171c924df0cfc024f2197339 (patch) | |
tree | 002b011f06152f99888cabf1cc528c1d53da17a9 /debian/patches/60-auth-rsa_psk-side-step-potential-side-channel.patch | |
parent | Adding upstream version 3.7.9. (diff) | |
download | gnutls28-99db386956013535171c924df0cfc024f2197339.tar.xz gnutls28-99db386956013535171c924df0cfc024f2197339.zip |
Adding debian version 3.7.9-2+deb12u2.debian/3.7.9-2+deb12u2
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'debian/patches/60-auth-rsa_psk-side-step-potential-side-channel.patch')
-rw-r--r-- | debian/patches/60-auth-rsa_psk-side-step-potential-side-channel.patch | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/debian/patches/60-auth-rsa_psk-side-step-potential-side-channel.patch b/debian/patches/60-auth-rsa_psk-side-step-potential-side-channel.patch new file mode 100644 index 0000000..e85c16a --- /dev/null +++ b/debian/patches/60-auth-rsa_psk-side-step-potential-side-channel.patch @@ -0,0 +1,229 @@ +From 29d6298d0b04cfff970b993915db71ba3f580b6d Mon Sep 17 00:00:00 2001 +From: Daiki Ueno <ueno@gnu.org> +Date: Mon, 23 Oct 2023 09:26:57 +0900 +Subject: [PATCH] auth/rsa_psk: side-step potential side-channel + +This removes branching that depends on secret data, porting changes +for regular RSA key exchange from +4804febddc2ed958e5ae774de2a8f85edeeff538 and +80a6ce8ddb02477cd724cd5b2944791aaddb702a. This also removes the +allow_wrong_pms as it was used sorely to control debug output +depending on the branching. + +Signed-off-by: Daiki Ueno <ueno@gnu.org> +--- + lib/auth/rsa.c | 2 +- + lib/auth/rsa_psk.c | 90 ++++++++++++++++++---------------------------- + lib/gnutls_int.h | 4 --- + lib/priority.c | 1 - + 4 files changed, 35 insertions(+), 62 deletions(-) + +--- a/lib/auth/rsa.c ++++ b/lib/auth/rsa.c +@@ -205,11 +205,11 @@ proc_rsa_client_kx(gnutls_session_t sess + 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 */ ++ * channel that can be used as an oracle, so tread carefully */ + + /* Error handling logic: + * In case decryption fails then don't inform the peer. Just use the + * random key previously generated. (in order to avoid attack against + * pkcs-1 formatting). +--- a/lib/auth/rsa_psk.c ++++ b/lib/auth/rsa_psk.c +@@ -262,18 +262,17 @@ static int + _gnutls_proc_rsa_psk_client_kx(gnutls_session_t session, uint8_t * data, + size_t _data_size) + { + gnutls_datum_t username; + psk_auth_info_t info; +- gnutls_datum_t plaintext; + gnutls_datum_t ciphertext; + gnutls_datum_t pwd_psk = { NULL, 0 }; + int ret, dsize; +- int randomize_key = 0; + ssize_t data_size = _data_size; + gnutls_psk_server_credentials_t cred; + gnutls_datum_t premaster_secret = { NULL, 0 }; ++ volatile uint8_t ver_maj, ver_min; + + cred = (gnutls_psk_server_credentials_t) + _gnutls_get_cred(session, GNUTLS_CRD_PSK); + + if (cred == NULL) { +@@ -327,75 +326,53 @@ _gnutls_proc_rsa_psk_client_kx(gnutls_se + gnutls_assert(); + return GNUTLS_E_UNEXPECTED_PACKET_LENGTH; + } + ciphertext.size = dsize; + +- ret = +- gnutls_privkey_decrypt_data(session->internals.selected_key, 0, +- &ciphertext, &plaintext); +- if (ret < 0 || plaintext.size != GNUTLS_MASTER_SIZE) { +- /* In case decryption fails then don't inform +- * the peer. Just use a random key. (in order to avoid +- * attack against pkcs-1 formatting). +- */ +- gnutls_assert(); +- _gnutls_debug_log +- ("auth_rsa_psk: Possible PKCS #1 format attack\n"); +- if (ret >= 0) { +- gnutls_free(plaintext.data); +- } +- randomize_key = 1; +- } else { +- /* If the secret was properly formatted, then +- * check the version number. +- */ +- if (_gnutls_get_adv_version_major(session) != +- plaintext.data[0] +- || (session->internals.allow_wrong_pms == 0 +- && _gnutls_get_adv_version_minor(session) != +- plaintext.data[1])) { +- /* No error is returned here, if the version number check +- * fails. We proceed normally. +- * That is to defend against the attack described in the paper +- * "Attacking RSA-based sessions in SSL/TLS" by Vlastimil Klima, +- * Ondej Pokorny and Tomas Rosa. +- */ +- gnutls_assert(); +- _gnutls_debug_log +- ("auth_rsa: Possible PKCS #1 version check format attack\n"); +- } +- } ++ ver_maj = _gnutls_get_adv_version_major(session); ++ ver_min = _gnutls_get_adv_version_minor(session); + ++ premaster_secret.data = gnutls_malloc(GNUTLS_MASTER_SIZE); ++ if (premaster_secret.data == NULL) { + +- if (randomize_key != 0) { +- premaster_secret.size = GNUTLS_MASTER_SIZE; +- premaster_secret.data = +- gnutls_malloc(premaster_secret.size); +- if (premaster_secret.data == NULL) { +- gnutls_assert(); +- return GNUTLS_E_MEMORY_ERROR; +- } +- +- /* we do not need strong random numbers here. +- */ +- ret = gnutls_rnd(GNUTLS_RND_NONCE, premaster_secret.data, +- premaster_secret.size); +- if (ret < 0) { +- gnutls_assert(); +- goto cleanup; +- } +- } else { +- premaster_secret.data = plaintext.data; +- premaster_secret.size = plaintext.size; ++ gnutls_assert(); ++ return GNUTLS_E_MEMORY_ERROR; + } ++ premaster_secret.size = GNUTLS_MASTER_SIZE; ++ ++ /* Fallback value when decryption fails. Needs to be unpredictable. */ ++ ret = gnutls_rnd(GNUTLS_RND_NONCE, premaster_secret.data, ++ premaster_secret.size); ++ if (ret < 0) { ++ gnutls_assert(); ++ goto cleanup; ++ } ++ ++ gnutls_privkey_decrypt_data2(session->internals.selected_key, 0, ++ &ciphertext, premaster_secret.data, ++ premaster_secret.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 tread carefully */ ++ ++ /* Error handling logic: ++ * In case decryption fails then don't inform the peer. Just use the ++ * random key previously generated. (in order to avoid attack against ++ * pkcs-1 formatting). ++ * ++ * If we get version mismatches no error is returned either. We ++ * proceed normally. This is to defend against the attack described ++ * in the paper "Attacking RSA-based sessions in SSL/TLS" by ++ * Vlastimil Klima, Ondej Pokorny and Tomas Rosa. ++ */ + + /* This is here to avoid the version check attack + * discussed above. + */ + +- premaster_secret.data[0] = _gnutls_get_adv_version_major(session); +- premaster_secret.data[1] = _gnutls_get_adv_version_minor(session); ++ premaster_secret.data[0] = ver_maj; ++ premaster_secret.data[1] = ver_min; + + /* find the key of this username + */ + ret = + _gnutls_psk_pwd_find_entry(session, info->username, strlen(info->username), &pwd_psk); +--- a/lib/gnutls_int.h ++++ b/lib/gnutls_int.h +@@ -983,11 +983,10 @@ struct gnutls_priority_st { + bool _allow_large_records; + bool _allow_small_records; + bool _no_etm; + bool _no_ext_master_secret; + bool _allow_key_usage_violation; +- bool _allow_wrong_pms; + bool _dumbfw; + unsigned int _dh_prime_bits; /* old (deprecated) variable */ + + DEF_ATOMIC_INT(usage_cnt); + }; +@@ -1001,20 +1000,18 @@ struct gnutls_priority_st { + (x)->allow_large_records = 1; \ + (x)->allow_small_records = 1; \ + (x)->no_etm = 1; \ + (x)->no_ext_master_secret = 1; \ + (x)->allow_key_usage_violation = 1; \ +- (x)->allow_wrong_pms = 1; \ + (x)->dumbfw = 1 + + #define ENABLE_PRIO_COMPAT(x) \ + (x)->_allow_large_records = 1; \ + (x)->_allow_small_records = 1; \ + (x)->_no_etm = 1; \ + (x)->_no_ext_master_secret = 1; \ + (x)->_allow_key_usage_violation = 1; \ +- (x)->_allow_wrong_pms = 1; \ + (x)->_dumbfw = 1 + + /* DH and RSA parameters types. + */ + typedef struct gnutls_dh_params_int { +@@ -1135,11 +1132,10 @@ typedef struct { + bool allow_large_records; + bool allow_small_records; + bool no_etm; + bool no_ext_master_secret; + bool allow_key_usage_violation; +- bool allow_wrong_pms; + bool dumbfw; + + /* old (deprecated) variable. This is used for both srp_prime_bits + * and dh_prime_bits as they don't overlap */ + /* For SRP: minimum bits to allow for SRP +--- a/lib/priority.c ++++ b/lib/priority.c +@@ -699,11 +699,10 @@ gnutls_priority_set(gnutls_session_t ses + COPY_TO_INTERNALS(allow_large_records); + COPY_TO_INTERNALS(allow_small_records); + COPY_TO_INTERNALS(no_etm); + COPY_TO_INTERNALS(no_ext_master_secret); + COPY_TO_INTERNALS(allow_key_usage_violation); +- COPY_TO_INTERNALS(allow_wrong_pms); + COPY_TO_INTERNALS(dumbfw); + COPY_TO_INTERNALS(dh_prime_bits); + + return 0; + } |