From: Hauke Mehrtens Date: Sun, 8 Sep 2019 21:53:18 +0000 (+0200) Subject: hostapd: SAE/EAP-pwd side-channel attack update X-Git-Tag: v21.02.0-rc1~5068 X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=7bed9bf10fc8d05df34c7efc66e8b4ade37a1a0c;p=openwrt%2Fstaging%2Fhauke.git hostapd: SAE/EAP-pwd side-channel attack update Fixes this security problem: * SAE/EAP-pwd side-channel attack update https://w1.fi/security/2019-6/sae-eap-pwd-side-channel-attack-update.txt Signed-off-by: Hauke Mehrtens --- diff --git a/package/network/services/hostapd/Makefile b/package/network/services/hostapd/Makefile index 18e4ea4490..233ef389ae 100644 --- a/package/network/services/hostapd/Makefile +++ b/package/network/services/hostapd/Makefile @@ -7,7 +7,7 @@ include $(TOPDIR)/rules.mk PKG_NAME:=hostapd -PKG_RELEASE:=8 +PKG_RELEASE:=9 PKG_SOURCE_URL:=http://w1.fi/hostap.git PKG_SOURCE_PROTO:=git diff --git a/package/network/services/hostapd/patches/066-0000-EAP-pwd-Disallow-ECC-groups-with-a-prime-under-256-b.patch b/package/network/services/hostapd/patches/066-0000-EAP-pwd-Disallow-ECC-groups-with-a-prime-under-256-b.patch new file mode 100644 index 0000000000..2d40516c7c --- /dev/null +++ b/package/network/services/hostapd/patches/066-0000-EAP-pwd-Disallow-ECC-groups-with-a-prime-under-256-b.patch @@ -0,0 +1,40 @@ +From 92e1b96c26a84e503847bdd22ebadf697c4031ad Mon Sep 17 00:00:00 2001 +From: Jouni Malinen +Date: Sat, 13 Apr 2019 17:20:57 +0300 +Subject: EAP-pwd: Disallow ECC groups with a prime under 256 bits + +Based on the SAE implementation guidance update to not allow ECC groups +with a prime that is under 256 bits, reject groups 25, 26, and 27 in +EAP-pwd. + +Signed-off-by: Jouni Malinen +--- + src/eap_common/eap_pwd_common.c | 13 +++++++++++++ + 1 file changed, 13 insertions(+) + +--- a/src/eap_common/eap_pwd_common.c ++++ b/src/eap_common/eap_pwd_common.c +@@ -85,10 +85,23 @@ static int eap_pwd_kdf(const u8 *key, si + } + + ++static int eap_pwd_suitable_group(u16 num) ++{ ++ /* Do not allow ECC groups with prime under 256 bits based on guidance ++ * for the similar design in SAE. */ ++ return num == 19 || num == 20 || num == 21 || ++ num == 28 || num == 29 || num == 30; ++} ++ ++ + EAP_PWD_group * get_eap_pwd_group(u16 num) + { + EAP_PWD_group *grp; + ++ if (!eap_pwd_suitable_group(num)) { ++ wpa_printf(MSG_INFO, "EAP-pwd: unsuitable group %u", num); ++ return NULL; ++ } + grp = os_zalloc(sizeof(EAP_PWD_group)); + if (!grp) + return NULL; diff --git a/package/network/services/hostapd/patches/066-0000-SAE-Reject-unsuitable-groups-based-on-REVmd-changes.patch b/package/network/services/hostapd/patches/066-0000-SAE-Reject-unsuitable-groups-based-on-REVmd-changes.patch new file mode 100644 index 0000000000..e1e743f52d --- /dev/null +++ b/package/network/services/hostapd/patches/066-0000-SAE-Reject-unsuitable-groups-based-on-REVmd-changes.patch @@ -0,0 +1,54 @@ +From db54db11aec763b6fc74715c36e0f9de0d65e206 Mon Sep 17 00:00:00 2001 +From: Jouni Malinen +Date: Mon, 8 Apr 2019 18:01:07 +0300 +Subject: SAE: Reject unsuitable groups based on REVmd changes + +The rules defining which DH groups are suitable for SAE use were +accepted into IEEE 802.11 REVmd based on this document: +https://mentor.ieee.org/802.11/dcn/19/11-19-0387-02-000m-addressing-some-sae-comments.docx + +Enforce those rules in production builds of wpa_supplicant and hostapd. +CONFIG_TESTING_OPTIONS=y builds can still be used to select any o the +implemented groups to maintain testing coverage. + +Signed-off-by: Jouni Malinen +--- + src/common/sae.c | 23 +++++++++++++++++++++++ + 1 file changed, 23 insertions(+) + +--- a/src/common/sae.c ++++ b/src/common/sae.c +@@ -18,10 +18,33 @@ + #include "sae.h" + + ++static int sae_suitable_group(int group) ++{ ++#ifdef CONFIG_TESTING_OPTIONS ++ /* Allow all groups for testing purposes in non-production builds. */ ++ return 1; ++#else /* CONFIG_TESTING_OPTIONS */ ++ /* Enforce REVmd rules on which SAE groups are suitable for production ++ * purposes: FFC groups whose prime is >= 3072 bits and ECC groups ++ * defined over a prime field whose prime is >= 256 bits. Furthermore, ++ * ECC groups defined over a characteristic 2 finite field and ECC ++ * groups with a co-factor greater than 1 are not suitable. */ ++ return group == 19 || group == 20 || group == 21 || ++ group == 28 || group == 29 || group == 30 || ++ group == 15 || group == 16 || group == 17 || group == 18; ++#endif /* CONFIG_TESTING_OPTIONS */ ++} ++ ++ + int sae_set_group(struct sae_data *sae, int group) + { + struct sae_temporary_data *tmp; + ++ if (!sae_suitable_group(group)) { ++ wpa_printf(MSG_DEBUG, "SAE: Reject unsuitable group %d", group); ++ return -1; ++ } ++ + sae_clear_data(sae); + tmp = sae->tmp = os_zalloc(sizeof(*tmp)); + if (tmp == NULL) diff --git a/package/network/services/hostapd/patches/066-0001-SAE-Use-const_time_memcmp-for-pwd_value-prime-compar.patch b/package/network/services/hostapd/patches/066-0001-SAE-Use-const_time_memcmp-for-pwd_value-prime-compar.patch new file mode 100644 index 0000000000..d637a52826 --- /dev/null +++ b/package/network/services/hostapd/patches/066-0001-SAE-Use-const_time_memcmp-for-pwd_value-prime-compar.patch @@ -0,0 +1,26 @@ +From e43f08991f00820c1f711ca254021d5f83b5cd7d Mon Sep 17 00:00:00 2001 +From: Jouni Malinen +Date: Thu, 25 Apr 2019 18:52:34 +0300 +Subject: [PATCH 1/6] SAE: Use const_time_memcmp() for pwd_value >= prime + comparison + +This reduces timing and memory access pattern differences for an +operation that could depend on the used password. + +Signed-off-by: Jouni Malinen +(cherry picked from commit 8e14b030e558d23f65d761895c07089404e61cf1) +--- + src/common/sae.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +--- a/src/common/sae.c ++++ b/src/common/sae.c +@@ -317,7 +317,7 @@ static int sae_test_pwd_seed_ecc(struct + wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value", + pwd_value, sae->tmp->prime_len); + +- if (os_memcmp(pwd_value, prime, sae->tmp->prime_len) >= 0) ++ if (const_time_memcmp(pwd_value, prime, sae->tmp->prime_len) >= 0) + return 0; + + x_cand = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len); diff --git a/package/network/services/hostapd/patches/066-0002-EAP-pwd-Use-const_time_memcmp-for-pwd_value-prime-co.patch b/package/network/services/hostapd/patches/066-0002-EAP-pwd-Use-const_time_memcmp-for-pwd_value-prime-co.patch new file mode 100644 index 0000000000..6bbda2bdb6 --- /dev/null +++ b/package/network/services/hostapd/patches/066-0002-EAP-pwd-Use-const_time_memcmp-for-pwd_value-prime-co.patch @@ -0,0 +1,65 @@ +From 20d7bd83c43fb24c4cf84d3045254d3ee1957166 Mon Sep 17 00:00:00 2001 +From: Jouni Malinen +Date: Thu, 25 Apr 2019 19:07:05 +0300 +Subject: [PATCH 2/6] EAP-pwd: Use const_time_memcmp() for pwd_value >= prime + comparison + +This reduces timing and memory access pattern differences for an +operation that could depend on the used password. + +Signed-off-by: Jouni Malinen +(cherry picked from commit 7958223fdcfe82479e6ed71019a84f6d4cbf799c) +--- + src/eap_common/eap_pwd_common.c | 13 ++++++++----- + 1 file changed, 8 insertions(+), 5 deletions(-) + +--- a/src/eap_common/eap_pwd_common.c ++++ b/src/eap_common/eap_pwd_common.c +@@ -144,6 +144,7 @@ int compute_password_element(EAP_PWD_gro + u8 qnr_bin[MAX_ECC_PRIME_LEN]; + u8 qr_or_qnr_bin[MAX_ECC_PRIME_LEN]; + u8 x_bin[MAX_ECC_PRIME_LEN]; ++ u8 prime_bin[MAX_ECC_PRIME_LEN]; + struct crypto_bignum *tmp1 = NULL, *tmp2 = NULL, *pm1 = NULL; + struct crypto_hash *hash; + unsigned char pwe_digest[SHA256_MAC_LEN], *prfbuf = NULL, ctr; +@@ -161,6 +162,11 @@ int compute_password_element(EAP_PWD_gro + os_memset(x_bin, 0, sizeof(x_bin)); + + prime = crypto_ec_get_prime(grp->group); ++ primebitlen = crypto_ec_prime_len_bits(grp->group); ++ primebytelen = crypto_ec_prime_len(grp->group); ++ if (crypto_bignum_to_bin(prime, prime_bin, sizeof(prime_bin), ++ primebytelen) < 0) ++ return -1; + cofactor = crypto_bignum_init(); + grp->pwe = crypto_ec_point_init(grp->group); + tmp1 = crypto_bignum_init(); +@@ -176,8 +182,6 @@ int compute_password_element(EAP_PWD_gro + "curve"); + goto fail; + } +- primebitlen = crypto_ec_prime_len_bits(grp->group); +- primebytelen = crypto_ec_prime_len(grp->group); + if ((prfbuf = os_malloc(primebytelen)) == NULL) { + wpa_printf(MSG_INFO, "EAP-pwd: unable to malloc space for prf " + "buffer"); +@@ -243,6 +247,8 @@ int compute_password_element(EAP_PWD_gro + if (primebitlen % 8) + buf_shift_right(prfbuf, primebytelen, + 8 - primebitlen % 8); ++ if (const_time_memcmp(prfbuf, prime_bin, primebytelen) >= 0) ++ continue; + + crypto_bignum_deinit(x_candidate, 1); + x_candidate = crypto_bignum_init_set(prfbuf, primebytelen); +@@ -252,9 +258,6 @@ int compute_password_element(EAP_PWD_gro + goto fail; + } + +- if (crypto_bignum_cmp(x_candidate, prime) >= 0) +- continue; +- + wpa_hexdump_key(MSG_DEBUG, "EAP-pwd: x_candidate", + prfbuf, primebytelen); + const_time_select_bin(found, x_bin, prfbuf, primebytelen, diff --git a/package/network/services/hostapd/patches/066-0003-OpenSSL-Use-BN_bn2binpad-or-BN_bn2bin_padded-if-avai.patch b/package/network/services/hostapd/patches/066-0003-OpenSSL-Use-BN_bn2binpad-or-BN_bn2bin_padded-if-avai.patch new file mode 100644 index 0000000000..67684cb140 --- /dev/null +++ b/package/network/services/hostapd/patches/066-0003-OpenSSL-Use-BN_bn2binpad-or-BN_bn2bin_padded-if-avai.patch @@ -0,0 +1,61 @@ +From ee34d8cfbd0fbf7ba7429531d4bee1c43b074d8b Mon Sep 17 00:00:00 2001 +From: Jouni Malinen +Date: Thu, 25 Apr 2019 19:23:05 +0300 +Subject: [PATCH 3/6] OpenSSL: Use BN_bn2binpad() or BN_bn2bin_padded() if + available + +This converts crypto_bignum_to_bin() to use the OpenSSL/BoringSSL +functions BN_bn2binpad()/BN_bn2bin_padded(), when available, to avoid +differences in runtime and memory access patterns depending on the +leading bytes of the BIGNUM value. + +OpenSSL 1.0.2 and LibreSSL do not include such functions, so those cases +are still using the previous implementation where the BN_num_bytes() +call may result in different memory access pattern. + +Signed-off-by: Jouni Malinen +(cherry picked from commit 1e237903f5b5d3117342daf006c5878cdb45e3d3) +--- + src/crypto/crypto_openssl.c | 16 ++++++++++++++++ + 1 file changed, 16 insertions(+) + +--- a/src/crypto/crypto_openssl.c ++++ b/src/crypto/crypto_openssl.c +@@ -1227,7 +1227,13 @@ void crypto_bignum_deinit(struct crypto_ + int crypto_bignum_to_bin(const struct crypto_bignum *a, + u8 *buf, size_t buflen, size_t padlen) + { ++#ifdef OPENSSL_IS_BORINGSSL ++#else /* OPENSSL_IS_BORINGSSL */ ++#if OPENSSL_VERSION_NUMBER >= 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER) ++#else + int num_bytes, offset; ++#endif ++#endif /* OPENSSL_IS_BORINGSSL */ + + if (TEST_FAIL()) + return -1; +@@ -1235,6 +1241,14 @@ int crypto_bignum_to_bin(const struct cr + if (padlen > buflen) + return -1; + ++#ifdef OPENSSL_IS_BORINGSSL ++ if (BN_bn2bin_padded(buf, padlen, (const BIGNUM *) a) == 0) ++ return -1; ++ return padlen; ++#else /* OPENSSL_IS_BORINGSSL */ ++#if OPENSSL_VERSION_NUMBER >= 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER) ++ return BN_bn2binpad((const BIGNUM *) a, buf, padlen); ++#else + num_bytes = BN_num_bytes((const BIGNUM *) a); + if ((size_t) num_bytes > buflen) + return -1; +@@ -1247,6 +1261,8 @@ int crypto_bignum_to_bin(const struct cr + BN_bn2bin((const BIGNUM *) a, buf + offset); + + return num_bytes + offset; ++#endif ++#endif /* OPENSSL_IS_BORINGSSL */ + } + + diff --git a/package/network/services/hostapd/patches/066-0004-SAE-Run-through-prf-result-processing-even-if-it-pri.patch b/package/network/services/hostapd/patches/066-0004-SAE-Run-through-prf-result-processing-even-if-it-pri.patch new file mode 100644 index 0000000000..7337cb35bd --- /dev/null +++ b/package/network/services/hostapd/patches/066-0004-SAE-Run-through-prf-result-processing-even-if-it-pri.patch @@ -0,0 +1,54 @@ +From a25b48118d75f3c2d7cb1b2c3b4cffb13091a34c Mon Sep 17 00:00:00 2001 +From: Jouni Malinen +Date: Mon, 24 Jun 2019 23:01:06 +0300 +Subject: [PATCH 4/6] SAE: Run through prf result processing even if it >= + prime + +This reduces differences in timing and memory access within the +hunting-and-pecking loop for ECC groups that have a prime that is not +close to a power of two (e.g., Brainpool curves). + +Signed-off-by: Jouni Malinen +(cherry picked from commit 147bf7b88a9c231322b5b574263071ca6dbb0503) +--- + src/common/sae.c | 15 ++++++++++++--- + 1 file changed, 12 insertions(+), 3 deletions(-) + +--- a/src/common/sae.c ++++ b/src/common/sae.c +@@ -304,6 +304,8 @@ static int sae_test_pwd_seed_ecc(struct + struct crypto_bignum *y_sqr, *x_cand; + int res; + size_t bits; ++ int cmp_prime; ++ unsigned int in_range; + + wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN); + +@@ -317,8 +319,13 @@ static int sae_test_pwd_seed_ecc(struct + wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value", + pwd_value, sae->tmp->prime_len); + +- if (const_time_memcmp(pwd_value, prime, sae->tmp->prime_len) >= 0) +- return 0; ++ cmp_prime = const_time_memcmp(pwd_value, prime, sae->tmp->prime_len); ++ /* Create a const_time mask for selection based on prf result ++ * being smaller than prime. */ ++ in_range = const_time_fill_msb((unsigned int) cmp_prime); ++ /* The algorithm description would skip the next steps if ++ * cmp_prime >= 0 (reutnr 0 here), but go through them regardless to ++ * minimize externally observable differences in behavior. */ + + x_cand = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len); + if (!x_cand) +@@ -330,7 +337,9 @@ static int sae_test_pwd_seed_ecc(struct + + res = is_quadratic_residue_blind(sae, prime, bits, qr, qnr, y_sqr); + crypto_bignum_deinit(y_sqr, 1); +- return res; ++ if (res < 0) ++ return res; ++ return const_time_select_int(in_range, res, 0); + } + + diff --git a/package/network/services/hostapd/patches/066-0005-EAP-pwd-Run-through-prf-result-processing-even-if-it.patch b/package/network/services/hostapd/patches/066-0005-EAP-pwd-Run-through-prf-result-processing-even-if-it.patch new file mode 100644 index 0000000000..9ad474757d --- /dev/null +++ b/package/network/services/hostapd/patches/066-0005-EAP-pwd-Run-through-prf-result-processing-even-if-it.patch @@ -0,0 +1,52 @@ +From 00a6cc73da61b03c146b6c341d0d1e572bcef432 Mon Sep 17 00:00:00 2001 +From: Jouni Malinen +Date: Mon, 24 Jun 2019 23:02:51 +0300 +Subject: [PATCH 5/6] EAP-pwd: Run through prf result processing even if it >= + prime + +This reduces differences in timing and memory access within the +hunting-and-pecking loop for ECC groups that have a prime that is not +close to a power of two (e.g., Brainpool curves). + +Signed-off-by: Jouni Malinen +(cherry picked from commit cd803299ca485eb857e37c88f973fccfbb8600e5) +--- + src/eap_common/eap_pwd_common.c | 13 ++++++++++--- + 1 file changed, 10 insertions(+), 3 deletions(-) + +--- a/src/eap_common/eap_pwd_common.c ++++ b/src/eap_common/eap_pwd_common.c +@@ -155,6 +155,8 @@ int compute_password_element(EAP_PWD_gro + struct crypto_bignum *x_candidate = NULL, *cofactor = NULL; + const struct crypto_bignum *prime; + u8 mask, found_ctr = 0, is_odd = 0; ++ int cmp_prime; ++ unsigned int in_range; + + if (grp->pwe) + return -1; +@@ -247,8 +249,13 @@ int compute_password_element(EAP_PWD_gro + if (primebitlen % 8) + buf_shift_right(prfbuf, primebytelen, + 8 - primebitlen % 8); +- if (const_time_memcmp(prfbuf, prime_bin, primebytelen) >= 0) +- continue; ++ cmp_prime = const_time_memcmp(prfbuf, prime_bin, primebytelen); ++ /* Create a const_time mask for selection based on prf result ++ * being smaller than prime. */ ++ in_range = const_time_fill_msb((unsigned int) cmp_prime); ++ /* The algorithm description would skip the next steps if ++ * cmp_prime >= 0, but go through them regardless to minimize ++ * externally observable differences in behavior. */ + + crypto_bignum_deinit(x_candidate, 1); + x_candidate = crypto_bignum_init_set(prfbuf, primebytelen); +@@ -311,7 +318,7 @@ int compute_password_element(EAP_PWD_gro + goto fail; + mask = const_time_eq(res, check); + found_ctr = const_time_select_u8(found, found_ctr, ctr); +- found |= mask; ++ found |= mask & in_range; + } + if (found == 0) { + wpa_printf(MSG_INFO, diff --git a/package/network/services/hostapd/patches/066-0006-dragonfly-Disable-use-of-groups-using-Brainpool-curv.patch b/package/network/services/hostapd/patches/066-0006-dragonfly-Disable-use-of-groups-using-Brainpool-curv.patch new file mode 100644 index 0000000000..28555bb715 --- /dev/null +++ b/package/network/services/hostapd/patches/066-0006-dragonfly-Disable-use-of-groups-using-Brainpool-curv.patch @@ -0,0 +1,44 @@ +From 558518ed63202e5358116ab7e0afd5e85490f2ef Mon Sep 17 00:00:00 2001 +From: Jouni Malinen +Date: Sat, 27 Jul 2019 23:19:17 +0300 +Subject: [PATCH 6/6] dragonfly: Disable use of groups using Brainpool curves + +Disable groups that use Brainpool curves for now since they leak more +timing information due to the prime not being close to a power of two. +This removes use of groups 28, 29, and 30 from SAE and EAP-pwd. + +Signed-off-by: Jouni Malinen +(cherry picked from commit 876c5eaa6dae1a87a17603fc489a44c29eedc2e3) +--- + src/common/sae.c | 6 ++++-- + src/eap_common/eap_pwd_common.c | 3 +-- + 2 files changed, 5 insertions(+), 4 deletions(-) + +--- a/src/common/sae.c ++++ b/src/common/sae.c +@@ -28,9 +28,11 @@ static int sae_suitable_group(int group) + * purposes: FFC groups whose prime is >= 3072 bits and ECC groups + * defined over a prime field whose prime is >= 256 bits. Furthermore, + * ECC groups defined over a characteristic 2 finite field and ECC +- * groups with a co-factor greater than 1 are not suitable. */ ++ * groups with a co-factor greater than 1 are not suitable. Disable ++ * groups that use Brainpool curves as well for now since they leak more ++ * timing information due to the prime not being close to a power of ++ * two. */ + return group == 19 || group == 20 || group == 21 || +- group == 28 || group == 29 || group == 30 || + group == 15 || group == 16 || group == 17 || group == 18; + #endif /* CONFIG_TESTING_OPTIONS */ + } +--- a/src/eap_common/eap_pwd_common.c ++++ b/src/eap_common/eap_pwd_common.c +@@ -89,8 +89,7 @@ static int eap_pwd_suitable_group(u16 nu + { + /* Do not allow ECC groups with prime under 256 bits based on guidance + * for the similar design in SAE. */ +- return num == 19 || num == 20 || num == 21 || +- num == 28 || num == 29 || num == 30; ++ return num == 19 || num == 20 || num == 21; + } + +