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authorMark H Weaver <mhw@netris.org>2020-06-02 14:05:46 -0400
committerMark H Weaver <mhw@netris.org>2020-06-02 14:05:46 -0400
commit7bc396bf353c5550c49b3f8791b34072ba417d90 (patch)
treed205b805297d2346fff6a4aabbdf2d536a7b98b5 /gnu/packages/patches
parent8f7cf3b50cda98afab1bef89bef2d6c01aa2b626 (diff)
gnu: nss: Fix CVE-2020-12399 via graft.
* gnu/packages/patches/nss-CVE-2020-12399.patch: New file. * gnu/local.mk (dist_patch_DATA): Add it. * gnu/packages/nss.scm (nss/fixed): New variable. (nss)[replacement]: Add field.
Diffstat (limited to 'gnu/packages/patches')
-rw-r--r--gnu/packages/patches/nss-CVE-2020-12399.patch138
1 files changed, 138 insertions, 0 deletions
diff --git a/gnu/packages/patches/nss-CVE-2020-12399.patch b/gnu/packages/patches/nss-CVE-2020-12399.patch
new file mode 100644
index 0000000000..0d91b655e2
--- /dev/null
+++ b/gnu/packages/patches/nss-CVE-2020-12399.patch
@@ -0,0 +1,138 @@
+Fix CVE-2020-12399 (Timing attack on DSA signature generation: NSS has
+shown timing differences when performing DSA signatures, which was
+exploitable and could eventually leak private keys.)
+
+Copied from upstream:
+<https://hg.mozilla.org/projects/nss/rev/daa823a4a29bcef0fec33a379ec83857429aea2e>
+but with "nss/" inserted into the file name to patch.
+
+# HG changeset patch
+# User Robert Relyea <rrelyea@redhat.com>
+# Date 1589907685 0
+# Node ID daa823a4a29bcef0fec33a379ec83857429aea2e
+# Parent d2cfb4ccdf167e5ea06d2bb5bc39c50f789929c8
+Bug 1631576 - Force a fixed length for DSA exponentiation r=pereida,bbrumley
+
+Differential Revision: https://phabricator.services.mozilla.com/D72011
+
+diff --git a/nss/lib/freebl/dsa.c b/nss/lib/freebl/dsa.c
+--- a/nss/lib/freebl/dsa.c
++++ b/nss/lib/freebl/dsa.c
+@@ -308,23 +308,24 @@ DSA_NewKeyFromSeed(const PQGParams *para
+ SECItem seedItem;
+ seedItem.data = (unsigned char *)seed;
+ seedItem.len = PQG_GetLength(&params->subPrime);
+ return dsa_NewKeyExtended(params, &seedItem, privKey);
+ }
+
+ 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;
+ SECItem localDigest;
+ unsigned char localDigestData[DSA_MAX_SUBPRIME_LEN];
+ SECItem t2 = { siBuffer, NULL, 0 };
+
+ /* FIPS-compliance dictates that digest is a SHA hash. */
+@@ -368,31 +369,46 @@ dsa_SignDigest(DSAPrivateKey *key, SECIt
+ CHECK_MPI_OK(mp_init(&q));
+ CHECK_MPI_OK(mp_init(&g));
+ CHECK_MPI_OK(mp_init(&x));
+ CHECK_MPI_OK(mp_init(&k));
+ CHECK_MPI_OK(mp_init(&r));
+ 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.
+ */
+ SECITEM_TO_MPINT(key->params.prime, &p);
+ 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
+ **
+ ** s = (k**-1 * (HASH(M) + x*r)) mod q
+ */
+ if (DSA_NewRandom(NULL, &key->params.subPrime, &t2) != SECSuccess) {
+ PORT_SetError(SEC_ERROR_NEED_RANDOM);
+ rv = SECFailure;
+@@ -406,25 +422,34 @@ dsa_SignDigest(DSAPrivateKey *key, SECIt
+ goto cleanup;
+ }
+ SECITEM_TO_MPINT(t2, &ar); /* ar <-$ Zq */
+ SECITEM_FreeItem(&t2, PR_FALSE);
+
+ /* 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.
+ */
+ if (mp_cmp_z(&r) == 0 || mp_cmp_z(&s) == 0) {
+ PORT_SetError(SEC_ERROR_NEED_RANDOM);
+ rv = SECFailure;
+ goto cleanup;
+