[PATCH 7/7] libgcrypt: fix CVE-2019-13627

[Anuj Mittal <anuj.mittal@intel.com>]

From: Trevor Gamblin <trevor.gamblin@windriver.com>

Backport two fixes for CVE-2019-13627 from upstream
to zeus.

Signed-off-by: Trevor Gamblin <trevor.gamblin@windriver.com>
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
---
 ...cdsa-Fix-use-of-nonce-use-larger-one.patch | 128 ++++++++++++++++++
 ...Add-mitigation-against-timing-attack.patch |  70 ++++++++++
 .../libgcrypt/libgcrypt_1.8.4.bb              |   2 +
 3 files changed, 200 insertions(+)
 create mode 100644 meta/recipes-support/libgcrypt/files/0001-dsa-ecdsa-Fix-use-of-nonce-use-larger-one.patch
 create mode 100644 meta/recipes-support/libgcrypt/files/0001-ecc-Add-mitigation-against-timing-attack.patch

diff --git a/meta/recipes-support/libgcrypt/files/0001-dsa-ecdsa-Fix-use-of-nonce-use-larger-one.patch b/meta/recipes-support/libgcrypt/files/0001-dsa-ecdsa-Fix-use-of-nonce-use-larger-one.patch
new file mode 100644
index 0000000000..211e041303
--- /dev/null
+++ b/meta/recipes-support/libgcrypt/files/0001-dsa-ecdsa-Fix-use-of-nonce-use-larger-one.patch
@@ -0,0 +1,128 @@
+From db4e9976cc31b314aafad6626b2894e86ee44d60 Mon Sep 17 00:00:00 2001
+From: NIIBE Yutaka <gniibe@fsij.org>
+Date: Thu, 8 Aug 2019 17:42:02 +0900
+Subject: [PATCH] dsa,ecdsa: Fix use of nonce, use larger one.
+
+Upstream-Status: Backport [https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commit;h=db4e9976cc3]
+CVE: CVE-2019-13627
+Signed-off-by: Trevor Gamblin <trevor.gamblin@windriver.com>
+
+* cipher/dsa-common.c (_gcry_dsa_modify_k): New.
+* cipher/pubkey-internal.h (_gcry_dsa_modify_k): New.
+* cipher/dsa.c (sign): Use _gcry_dsa_modify_k.
+* cipher/ecc-ecdsa.c (_gcry_ecc_ecdsa_sign): Likewise.
+* cipher/ecc-gost.c (_gcry_ecc_gost_sign): Likewise.
+
+--
+
+Cherry-picked master commit of:
+	7c2943309d14407b51c8166c4dcecb56a3628567
+
+CVE-id: CVE-2019-13627
+GnuPG-bug-id: 4626
+Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
+---
+ cipher/dsa-common.c      | 24 ++++++++++++++++++++++++
+ cipher/dsa.c             |  2 ++
+ cipher/ecc-ecdsa.c       | 10 +---------
+ cipher/ecc-gost.c        |  2 ++
+ cipher/pubkey-internal.h |  1 +
+ 5 files changed, 30 insertions(+), 9 deletions(-)
+
+diff --git a/cipher/dsa-common.c b/cipher/dsa-common.c
+index 8c0a6843..fe49248d 100644
+--- a/cipher/dsa-common.c
++++ b/cipher/dsa-common.c
+@@ -29,6 +29,30 @@
+ #include "pubkey-internal.h"
+ 
+ 
++/*
++ * Modify K, so that computation time difference can be small,
++ * by making K large enough.
++ *
++ * Originally, (EC)DSA computation requires k where 0 < k < q.  Here,
++ * we add q (the order), to keep k in a range: q < k < 2*q (or,
++ * addming more q, to keep k in a range: 2*q < k < 3*q), so that
++ * timing difference of the EC multiply (or exponentiation) operation
++ * can be small.  The result of (EC)DSA computation is same.
++ */
++void
++_gcry_dsa_modify_k (gcry_mpi_t k, gcry_mpi_t q, int qbits)
++{
++  gcry_mpi_t k1 = mpi_new (qbits+2);
++
++  mpi_resize (k, (qbits+2+BITS_PER_MPI_LIMB-1) / BITS_PER_MPI_LIMB);
++  k->nlimbs = k->alloced;
++  mpi_add (k, k, q);
++  mpi_add (k1, k, q);
++  mpi_set_cond (k, k1, !mpi_test_bit (k, qbits));
++
++  mpi_free (k1);
++}
++
+ /*
+  * Generate a random secret exponent K less than Q.
+  * Note that ECDSA uses this code also to generate D.
+diff --git a/cipher/dsa.c b/cipher/dsa.c
+index 22d8d782..24a53528 100644
+--- a/cipher/dsa.c
++++ b/cipher/dsa.c
+@@ -635,6 +635,8 @@ sign (gcry_mpi_t r, gcry_mpi_t s, gcry_mpi_t input, DSA_secret_key *skey,
+       k = _gcry_dsa_gen_k (skey->q, GCRY_STRONG_RANDOM);
+     }
+ 
++  _gcry_dsa_modify_k (k, skey->q, qbits);
++
+   /* r = (a^k mod p) mod q */
+   mpi_powm( r, skey->g, k, skey->p );
+   mpi_fdiv_r( r, r, skey->q );
+diff --git a/cipher/ecc-ecdsa.c b/cipher/ecc-ecdsa.c
+index 84a1cf84..97966c3a 100644
+--- a/cipher/ecc-ecdsa.c
++++ b/cipher/ecc-ecdsa.c
+@@ -114,15 +114,7 @@ _gcry_ecc_ecdsa_sign (gcry_mpi_t input, ECC_secret_key *skey,
+           else
+             k = _gcry_dsa_gen_k (skey->E.n, GCRY_STRONG_RANDOM);
+ 
+-          /* Originally, ECDSA computation requires k where 0 < k < n.
+-           * Here, we add n (the order of curve), to keep k in a
+-           * range: n < k < 2*n, or, addming more n, keep k in a range:
+-           * 2*n < k < 3*n, so that timing difference of the EC
+-           * multiply operation can be small.  The result is same.
+-           */
+-          mpi_add (k, k, skey->E.n);
+-          if (!mpi_test_bit (k, qbits))
+-            mpi_add (k, k, skey->E.n);
++          _gcry_dsa_modify_k (k, skey->E.n, qbits);
+ 
+           _gcry_mpi_ec_mul_point (&I, k, &skey->E.G, ctx);
+           if (_gcry_mpi_ec_get_affine (x, NULL, &I, ctx))
+diff --git a/cipher/ecc-gost.c b/cipher/ecc-gost.c
+index a34fa084..0362a6c7 100644
+--- a/cipher/ecc-gost.c
++++ b/cipher/ecc-gost.c
+@@ -94,6 +94,8 @@ _gcry_ecc_gost_sign (gcry_mpi_t input, ECC_secret_key *skey,
+           mpi_free (k);
+           k = _gcry_dsa_gen_k (skey->E.n, GCRY_STRONG_RANDOM);
+ 
++          _gcry_dsa_modify_k (k, skey->E.n, qbits);
++
+           _gcry_mpi_ec_mul_point (&I, k, &skey->E.G, ctx);
+           if (_gcry_mpi_ec_get_affine (x, NULL, &I, ctx))
+             {
+diff --git a/cipher/pubkey-internal.h b/cipher/pubkey-internal.h
+index b8167c77..d31e26f3 100644
+--- a/cipher/pubkey-internal.h
++++ b/cipher/pubkey-internal.h
+@@ -84,6 +84,7 @@ _gcry_rsa_pss_verify (gcry_mpi_t value, gcry_mpi_t encoded,
+ 
+ 
+ /*-- dsa-common.c --*/
++void _gcry_dsa_modify_k (gcry_mpi_t k, gcry_mpi_t q, int qbits);
+ gcry_mpi_t _gcry_dsa_gen_k (gcry_mpi_t q, int security_level);
+ gpg_err_code_t _gcry_dsa_gen_rfc6979_k (gcry_mpi_t *r_k,
+                                         gcry_mpi_t dsa_q, gcry_mpi_t dsa_x,
+-- 
+2.23.0
+
diff --git a/meta/recipes-support/libgcrypt/files/0001-ecc-Add-mitigation-against-timing-attack.patch b/meta/recipes-support/libgcrypt/files/0001-ecc-Add-mitigation-against-timing-attack.patch
new file mode 100644
index 0000000000..db5a55ed26
--- /dev/null
+++ b/meta/recipes-support/libgcrypt/files/0001-ecc-Add-mitigation-against-timing-attack.patch
@@ -0,0 +1,70 @@
+From d5407b78cca9f9d318a4f4d2f6ba2b8388584cd9 Mon Sep 17 00:00:00 2001
+From: NIIBE Yutaka <gniibe@fsij.org>
+Date: Wed, 17 Jul 2019 12:44:50 +0900
+Subject: [PATCH] ecc: Add mitigation against timing attack.
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Upstream-Status: Backport [https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commit;h=d5407b78c]
+CVE: CVE-2019-13627
+Signed-off-by: Trevor Gamblin <trevor.gamblin@windriver.com>
+
+* cipher/ecc-ecdsa.c (_gcry_ecc_ecdsa_sign): Add the order N to K.
+* mpi/ec.c (_gcry_mpi_ec_mul_point): Compute with NBITS of P or larger.
+
+--
+
+Cherry-picked master commit of:
+	 b9577f7c89b4327edc09f2231bc8b31521102c79
+
+CVE-id: CVE-2019-13627
+GnuPG-bug-id: 4626
+Co-authored-by: Ján Jančár <johny@neuromancer.sk>
+Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
+---
+ cipher/ecc-ecdsa.c | 10 ++++++++++
+ mpi/ec.c           |  6 +++++-
+ 2 files changed, 15 insertions(+), 1 deletion(-)
+
+diff --git a/cipher/ecc-ecdsa.c b/cipher/ecc-ecdsa.c
+index 140e8c09..84a1cf84 100644
+--- a/cipher/ecc-ecdsa.c
++++ b/cipher/ecc-ecdsa.c
+@@ -114,6 +114,16 @@ _gcry_ecc_ecdsa_sign (gcry_mpi_t input, ECC_secret_key *skey,
+           else
+             k = _gcry_dsa_gen_k (skey->E.n, GCRY_STRONG_RANDOM);
+ 
++          /* Originally, ECDSA computation requires k where 0 < k < n.
++           * Here, we add n (the order of curve), to keep k in a
++           * range: n < k < 2*n, or, addming more n, keep k in a range:
++           * 2*n < k < 3*n, so that timing difference of the EC
++           * multiply operation can be small.  The result is same.
++           */
++          mpi_add (k, k, skey->E.n);
++          if (!mpi_test_bit (k, qbits))
++            mpi_add (k, k, skey->E.n);
++
+           _gcry_mpi_ec_mul_point (&I, k, &skey->E.G, ctx);
+           if (_gcry_mpi_ec_get_affine (x, NULL, &I, ctx))
+             {
+diff --git a/mpi/ec.c b/mpi/ec.c
+index 89077cd9..adb02600 100644
+--- a/mpi/ec.c
++++ b/mpi/ec.c
+@@ -1309,7 +1309,11 @@ _gcry_mpi_ec_mul_point (mpi_point_t result,
+       unsigned int nbits;
+       int j;
+ 
+-      nbits = mpi_get_nbits (scalar);
++      if (mpi_cmp (scalar, ctx->p) >= 0)
++        nbits = mpi_get_nbits (scalar);
++      else
++        nbits = mpi_get_nbits (ctx->p);
++
+       if (ctx->model == MPI_EC_WEIERSTRASS)
+         {
+           mpi_set_ui (result->x, 1);
+-- 
+2.23.0
+
diff --git a/meta/recipes-support/libgcrypt/libgcrypt_1.8.4.bb b/meta/recipes-support/libgcrypt/libgcrypt_1.8.4.bb
index 11d078d44a..1bd355133e 100644
--- a/meta/recipes-support/libgcrypt/libgcrypt_1.8.4.bb
+++ b/meta/recipes-support/libgcrypt/libgcrypt_1.8.4.bb
@@ -24,6 +24,8 @@ SRC_URI = "${GNUPG_MIRROR}/libgcrypt/libgcrypt-${PV}.tar.bz2 \
            file://0001-Prefetch-GCM-look-up-tables.patch \
            file://0002-AES-move-look-up-tables-to-.data-section-and-unshare.patch \
            file://0003-GCM-move-look-up-table-to-.data-section-and-unshare-.patch \
+           file://0001-ecc-Add-mitigation-against-timing-attack.patch \
+           file://0001-dsa-ecdsa-Fix-use-of-nonce-use-larger-one.patch \
 "
 SRC_URI[md5sum] = "fbfdaebbbc6d7e5fbbf6ffdb3e139573"
 SRC_URI[sha256sum] = "f638143a0672628fde0cad745e9b14deb85dffb175709cacc1f4fe24b93f2227"
-- 
2.21.0