The CVE-2018-0737 fix consists of commits: 9db724cfede4ba7a3668bff533973ee70145ec07 011f82e66f4bf131c733fd41a8390039859aafb2 7150a4720af7913cae16f2e4eaf768b578c0b298 (the three above are included in 1.1.0h) 6939eab03a6e23d2bd2c3f5e34fe1d48e542e787 and additional changes to our fips_rsa_keygen() From 6939eab03a6e23d2bd2c3f5e34fe1d48e542e787 Mon Sep 17 00:00:00 2001 From: Billy Brumley Date: Wed, 11 Apr 2018 10:10:58 +0300 Subject: [PATCH] RSA key generation: ensure BN_mod_inverse and BN_mod_exp_mont both get called with BN_FLG_CONSTTIME flag set. CVE-2018-0737 Reviewed-by: Rich Salz Reviewed-by: Matt Caswell --- crypto/rsa/rsa_gen.c | 2 ++ 1 file changed, 2 insertions(+) Index: openssl-1.1.0h/crypto/rsa/rsa_gen.c =================================================================== --- openssl-1.1.0h.orig/crypto/rsa/rsa_gen.c 2018-05-10 11:50:53.298706226 +0200 +++ openssl-1.1.0h/crypto/rsa/rsa_gen.c 2018-05-10 12:55:39.394968170 +0200 @@ -123,6 +123,7 @@ static int fips_rsa_builtin_keygen(RSA * int n = 0; int test = 0; int pbits = bits / 2; + unsigned long error = 0; if (FIPS_selftest_failed()) { FIPSerr(FIPS_F_FIPS_RSA_BUILTIN_KEYGEN, FIPS_R_FIPS_SELFTEST_FAILED); @@ -191,6 +192,10 @@ retry: if (!BN_lshift(r3, r3, pbits - 100)) goto err; + BN_set_flags(rsa->p, BN_FLG_CONSTTIME); + BN_set_flags(rsa->q, BN_FLG_CONSTTIME); + BN_set_flags(r2, BN_FLG_CONSTTIME); + /* generate p and q */ for (i = 0; i < 5 * pbits; i++) { ploop: @@ -205,9 +210,9 @@ retry: if (!BN_sub(r2, rsa->p, BN_value_one())) goto err; - if (!BN_gcd(r1, r2, rsa->e, ctx)) - goto err; - if (BN_is_one(r1)) { + ERR_set_mark(); + if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) { + /* GCD == 1 since inverse exists */ int r; r = BN_is_prime_fasttest_ex(rsa->p, pbits > 1024 ? 4 : 5, ctx, 0, cb); @@ -217,6 +222,15 @@ retry: break; } + error = ERR_peek_last_error(); + if (ERR_GET_LIB(error) == ERR_LIB_BN + && ERR_GET_REASON(error) == BN_R_NO_INVERSE) { + /* GCD != 1 */ + ERR_pop_to_mark(); + } else { + goto err; + } + if (!BN_GENCB_call(cb, 2, n++)) goto err; } @@ -248,9 +262,9 @@ retry: if (!BN_sub(r2, rsa->q, BN_value_one())) goto err; - if (!BN_gcd(r1, r2, rsa->e, ctx)) - goto err; - if (BN_is_one(r1)) { + ERR_set_mark(); + if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) { + /* GCD == 1 since inverse exists */ int r; r = BN_is_prime_fasttest_ex(rsa->q, pbits > 1024 ? 4 : 5, ctx, 0, cb); @@ -260,6 +274,15 @@ retry: break; } + error = ERR_peek_last_error(); + if (ERR_GET_LIB(error) == ERR_LIB_BN + && ERR_GET_REASON(error) == BN_R_NO_INVERSE) { + /* GCD != 1 */ + ERR_pop_to_mark(); + } else { + goto err; + } + if (!BN_GENCB_call(cb, 2, n++)) goto err; } @@ -457,6 +480,8 @@ static int rsa_builtin_keygen(RSA *rsa, if (BN_copy(rsa->e, e_value) == NULL) goto err; + BN_set_flags(rsa->p, BN_FLG_CONSTTIME); + BN_set_flags(rsa->q, BN_FLG_CONSTTIME); BN_set_flags(r2, BN_FLG_CONSTTIME); /* generate p and q */ for (;;) {