Master (nss version 3.54) is not affected by this issue. This is a backport from nss version 3.54.
NSS has shown timing differences when performing DSA signatures, which was exploitable and could eventually leak private keys. This vulnerability affects Thunderbird < 68.9.0, Firefox < 77, and Firefox ESR < 68.9. Upstream patch: https://hg.mozilla.org/projects/nss/rev/daa823a4a29bcef0fec33a379ec83857429aea2e Signed-off-by: Ovidiu Panait <ovidiu.pan...@windriver.com> --- ...e-a-fixed-length-for-DSA-exponentiat.patch | 110 ++++++++++++++++++ meta-oe/recipes-support/nss/nss_3.51.1.bb | 1 + 2 files changed, 111 insertions(+) create mode 100644 meta-oe/recipes-support/nss/nss/0001-Bug-1631576-Force-a-fixed-length-for-DSA-exponentiat.patch diff --git a/meta-oe/recipes-support/nss/nss/0001-Bug-1631576-Force-a-fixed-length-for-DSA-exponentiat.patch b/meta-oe/recipes-support/nss/nss/0001-Bug-1631576-Force-a-fixed-length-for-DSA-exponentiat.patch new file mode 100644 index 000000000..517c277ae --- /dev/null +++ b/meta-oe/recipes-support/nss/nss/0001-Bug-1631576-Force-a-fixed-length-for-DSA-exponentiat.patch @@ -0,0 +1,110 @@ +From 5942c26888ba12ad5e0d92fb62f23d7cde6dc159 Mon Sep 17 00:00:00 2001 +From: Ovidiu Panait <ovidiu.pan...@windriver.com> +Date: Mon, 13 Jul 2020 06:25:56 +0000 +Subject: [PATCH] Bug 1631576 - Force a fixed length for DSA exponentiation + r=pereida,bbrumley + +Differential Revision: https://phabricator.services.mozilla.com/D72011 + +Upstream-Status: Backport [https://hg.mozilla.org/projects/nss/rev/daa823a4a29bcef0fec33a379ec83857429aea2e] + +Authored-by: Robert Relyea <rrel...@redhat.com> +Signed-off-by: Ovidiu Panait <ovidiu.pan...@windriver.com> +--- + nss/lib/freebl/dsa.c | 45 ++++++++++++++++++++++++++++++++++---------- + 1 file changed, 35 insertions(+), 10 deletions(-) + +diff --git a/nss/lib/freebl/dsa.c b/nss/lib/freebl/dsa.c +index aef3539..389c9de 100644 +--- a/nss/lib/freebl/dsa.c ++++ b/nss/lib/freebl/dsa.c +@@ -313,13 +313,14 @@ DSA_NewKeyFromSeed(const PQGParams *params, + + static SECStatus + dsa_SignDigest(DSAPrivateKey *key, SECItem *signature, const SECItem *digest, +- const unsigned char *kb) ++ const unsigned char *kbytes) + { + mp_int p, q, g; /* PQG parameters */ + mp_int x, k; /* private key & pseudo-random integer */ + mp_int r, s; /* tuple (r, s) is signature) */ + mp_int t; /* holding tmp values */ + mp_int ar; /* holding blinding values */ ++ mp_digit fuzz; /* blinding multiplier for q */ + mp_err err = MP_OKAY; + SECStatus rv = SECSuccess; + unsigned int dsa_subprime_len, dsa_signature_len, offset; +@@ -373,6 +374,7 @@ dsa_SignDigest(DSAPrivateKey *key, SECItem *signature, const SECItem *digest, + CHECK_MPI_OK(mp_init(&s)); + CHECK_MPI_OK(mp_init(&t)); + CHECK_MPI_OK(mp_init(&ar)); ++ + /* + ** Convert stored PQG and private key into MPI integers. + */ +@@ -380,14 +382,28 @@ dsa_SignDigest(DSAPrivateKey *key, SECItem *signature, const SECItem *digest, + SECITEM_TO_MPINT(key->params.subPrime, &q); + SECITEM_TO_MPINT(key->params.base, &g); + SECITEM_TO_MPINT(key->privateValue, &x); +- OCTETS_TO_MPINT(kb, &k, dsa_subprime_len); ++ OCTETS_TO_MPINT(kbytes, &k, dsa_subprime_len); ++ ++ /* k blinding create a single value that has the high bit set in ++ * the mp_digit*/ ++ if (RNG_GenerateGlobalRandomBytes(&fuzz, sizeof(mp_digit)) != SECSuccess) { ++ PORT_SetError(SEC_ERROR_NEED_RANDOM); ++ rv = SECFailure; ++ goto cleanup; ++ } ++ fuzz |= 1ULL << ((sizeof(mp_digit) * PR_BITS_PER_BYTE - 1)); + /* + ** FIPS 186-1, Section 5, Step 1 + ** + ** r = (g**k mod p) mod q + */ +- CHECK_MPI_OK(mp_exptmod(&g, &k, &p, &r)); /* r = g**k mod p */ +- CHECK_MPI_OK(mp_mod(&r, &q, &r)); /* r = r mod q */ ++ CHECK_MPI_OK(mp_mul_d(&q, fuzz, &t)); /* t = q*fuzz */ ++ CHECK_MPI_OK(mp_add(&k, &t, &t)); /* t = k+q*fuzz */ ++ /* length of t is now fixed, bits in k have been blinded */ ++ CHECK_MPI_OK(mp_exptmod(&g, &t, &p, &r)); /* r = g**t mod p */ ++ /* r is now g**(k+q*fuzz) == g**k mod p */ ++ CHECK_MPI_OK(mp_mod(&r, &q, &r)); /* r = r mod q */ ++ + /* + ** FIPS 186-1, Section 5, Step 2 + ** +@@ -411,15 +427,24 @@ dsa_SignDigest(DSAPrivateKey *key, SECItem *signature, const SECItem *digest, + /* Using mp_invmod on k directly would leak bits from k. */ + CHECK_MPI_OK(mp_mul(&k, &ar, &k)); /* k = k * ar */ + CHECK_MPI_OK(mp_mulmod(&k, &t, &q, &k)); /* k = k * t mod q */ +- CHECK_MPI_OK(mp_invmod(&k, &q, &k)); /* k = k**-1 mod q */ ++ /* k is now k*t*ar */ ++ CHECK_MPI_OK(mp_invmod(&k, &q, &k)); /* k = k**-1 mod q */ ++ /* k is now (k*t*ar)**-1 */ + CHECK_MPI_OK(mp_mulmod(&k, &t, &q, &k)); /* k = k * t mod q */ +- SECITEM_TO_MPINT(localDigest, &s); /* s = HASH(M) */ ++ /* k is now (k*ar)**-1 */ ++ SECITEM_TO_MPINT(localDigest, &s); /* s = HASH(M) */ + /* To avoid leaking secret bits here the addition is blinded. */ +- CHECK_MPI_OK(mp_mul(&x, &ar, &x)); /* x = x * ar */ +- CHECK_MPI_OK(mp_mulmod(&x, &r, &q, &x)); /* x = x * r mod q */ ++ CHECK_MPI_OK(mp_mul(&x, &ar, &x)); /* x = x * ar */ ++ /* x is now x*ar */ ++ CHECK_MPI_OK(mp_mulmod(&x, &r, &q, &x)); /* x = x * r mod q */ ++ /* x is now x*r*ar */ + CHECK_MPI_OK(mp_mulmod(&s, &ar, &q, &t)); /* t = s * ar mod q */ +- CHECK_MPI_OK(mp_add(&t, &x, &s)); /* s = t + x */ +- CHECK_MPI_OK(mp_mulmod(&s, &k, &q, &s)); /* s = s * k mod q */ ++ /* t is now hash(M)*ar */ ++ CHECK_MPI_OK(mp_add(&t, &x, &s)); /* s = t + x */ ++ /* s is now (HASH(M)+x*r)*ar */ ++ CHECK_MPI_OK(mp_mulmod(&s, &k, &q, &s)); /* s = s * k mod q */ ++ /* s is now (HASH(M)+x*r)*ar*(k*ar)**-1 = (k**-1)*(HASH(M)+x*r) */ ++ + /* + ** verify r != 0 and s != 0 + ** mentioned as optional in FIPS 186-1. +-- +2.18.1 + diff --git a/meta-oe/recipes-support/nss/nss_3.51.1.bb b/meta-oe/recipes-support/nss/nss_3.51.1.bb index fba80ce2a..3d2c1340e 100644 --- a/meta-oe/recipes-support/nss/nss_3.51.1.bb +++ b/meta-oe/recipes-support/nss/nss_3.51.1.bb @@ -34,6 +34,7 @@ SRC_URI = "http://ftp.mozilla.org/pub/mozilla.org/security/nss/releases/${VERSIO file://0001-freebl-add-a-configure-option-to-disable-ARM-HW-cryp.patch \ file://riscv.patch \ file://0001-Enable-uint128-on-mips64.patch \ + file://0001-Bug-1631576-Force-a-fixed-length-for-DSA-exponentiat.patch \ " SRC_URI[md5sum] = "6acaf1ddff69306ae30a908881c6f233" -- 2.17.1
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