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gnu: nettle-3.5: Add replacement to fix CVE-2021-3580 et al. 

* gnu/packages/patches/nettle-3.5-check-_pkcs1_sec_decrypt-msg-len.patch,
gnu/packages/patches/nettle-3.5-CVE-2021-3580-pt1.patch,
gnu/packages/patches/nettle-3.5-CVE-2021-3580-pt2.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/nettle.scm (nettle)[replacement]: New field.
(nettle-3.5/fixed): New variable.
master
Mark H Weaver 2021-06-13 20:03:29 -04:00
parent d3acad1626
commit 3abaca2aae
No known key found for this signature in database
GPG Key ID: 7CEF29847562C516
5 changed files with 530 additions and 1 deletions
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3
gnu/local.mk
View File

@ -1462,6 +1462,9 @@ dist_patch_DATA = \
%D%/packages/patches/netsurf-system-utf8proc.patch \ %D%/packages/patches/netsurf-system-utf8proc.patch \
%D%/packages/patches/netsurf-y2038-tests.patch \ %D%/packages/patches/netsurf-y2038-tests.patch \
%D%/packages/patches/netsurf-longer-test-timeout.patch \ %D%/packages/patches/netsurf-longer-test-timeout.patch \
%D%/packages/patches/nettle-3.5-check-_pkcs1_sec_decrypt-msg-len.patch \
%D%/packages/patches/nettle-3.5-CVE-2021-3580-pt1.patch \
%D%/packages/patches/nettle-3.5-CVE-2021-3580-pt2.patch \
%D%/packages/patches/nfs4-acl-tools-0.3.7-fixpaths.patch \ %D%/packages/patches/nfs4-acl-tools-0.3.7-fixpaths.patch \
%D%/packages/patches/ngircd-handle-zombies.patch \ %D%/packages/patches/ngircd-handle-zombies.patch \
%D%/packages/patches/network-manager-plugin-path.patch \ %D%/packages/patches/network-manager-plugin-path.patch \

11
gnu/packages/nettle.scm
View File

@ -1,6 +1,6 @@
;;; GNU Guix --- Functional package management for GNU ;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org> ;;; Copyright © 2012, 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 Mark H Weaver <mhw@netris.org> ;;; Copyright © 2016, 2021 Mark H Weaver <mhw@netris.org>
;;; Copyright © 2017 Efraim Flashner <efraim@flashner.co.il> ;;; Copyright © 2017 Efraim Flashner <efraim@flashner.co.il>
;;; Copyright © 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com> ;;; Copyright © 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; ;;;
@ -25,6 +25,7 @@
#:use-module (guix packages) #:use-module (guix packages)
#:use-module (guix download) #:use-module (guix download)
#:use-module (guix build-system gnu) #:use-module (guix build-system gnu)
#:use-module (gnu packages)
#:use-module (gnu packages multiprecision) #:use-module (gnu packages multiprecision)
#:use-module (gnu packages m4)) #:use-module (gnu packages m4))
@ -77,6 +78,7 @@ themselves.")
;; cannot use it yet. So keep it separate. ;; cannot use it yet. So keep it separate.
(package (inherit nettle-2) (package (inherit nettle-2)
(version "3.5.1") (version "3.5.1")
(replacement nettle-3.5/fixed)
(source (origin (source (origin
(method url-fetch) (method url-fetch)
(uri (string-append "mirror://gnu/nettle/nettle-" (uri (string-append "mirror://gnu/nettle/nettle-"
@ -91,6 +93,13 @@ themselves.")
;; at run time based on CPU features (starting from 3.1.) ;; at run time based on CPU features (starting from 3.1.)
`(cons "--enable-fat" ,flags)))))) `(cons "--enable-fat" ,flags))))))
(define nettle-3.5/fixed
(package-with-extra-patches
nettle-3.5
(search-patches "nettle-3.5-check-_pkcs1_sec_decrypt-msg-len.patch"
"nettle-3.5-CVE-2021-3580-pt1.patch"
"nettle-3.5-CVE-2021-3580-pt2.patch")))
(define-public nettle-3.7 (define-public nettle-3.7
(package (inherit nettle-3.5) (package (inherit nettle-3.5)
(version "3.7.2") (version "3.7.2")

276
gnu/packages/patches/nettle-3.5-CVE-2021-3580-pt1.patch 100644
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@ -0,0 +1,276 @@
Copied from upstream nettle git repository.
Removed changes to ChangeLog, to allow this patch to apply to nettle-3.5.
From 485b5e2820a057e873b1ba812fdb39cae4adf98c Mon Sep 17 00:00:00 2001
From: Niels Möller <nisse@lysator.liu.se>
Date: Mon, 17 May 2021 20:55:26 +0200
Subject: [PATCH 1/2] Change _rsa_sec_compute_root_tr to take a fix input size.
Improves consistency with _rsa_sec_compute_root, and fixes zero-input bug.
---
ChangeLog | 15 +++++++++
rsa-decrypt-tr.c | 7 ++---
rsa-internal.h | 4 +--
rsa-sec-decrypt.c | 9 ++++--
rsa-sign-tr.c | 61 +++++++++++++++++-------------------
testsuite/rsa-encrypt-test.c | 14 ++++++++-
6 files changed, 68 insertions(+), 42 deletions(-)
diff --git a/rsa-decrypt-tr.c b/rsa-decrypt-tr.c
index 0224c0b7..927a8915 100644
--- a/rsa-decrypt-tr.c
+++ b/rsa-decrypt-tr.c
@@ -52,14 +52,13 @@ rsa_decrypt_tr(const struct rsa_public_key *pub,
mp_size_t key_limb_size;
int res;
- key_limb_size = NETTLE_OCTET_SIZE_TO_LIMB_SIZE(key->size);
+ key_limb_size = mpz_size(pub->n);
TMP_GMP_ALLOC (m, key_limb_size);
TMP_GMP_ALLOC (em, key->size);
+ mpz_limbs_copy(m, gibberish, key_limb_size);
- res = _rsa_sec_compute_root_tr (pub, key, random_ctx, random, m,
- mpz_limbs_read(gibberish),
- mpz_size(gibberish));
+ res = _rsa_sec_compute_root_tr (pub, key, random_ctx, random, m, m);
mpn_get_base256 (em, key->size, m, key_limb_size);
diff --git a/rsa-internal.h b/rsa-internal.h
index b828e451..f66a7df0 100644
--- a/rsa-internal.h
+++ b/rsa-internal.h
@@ -78,11 +78,11 @@ _rsa_sec_compute_root(const struct rsa_private_key *key,
mp_limb_t *scratch);
/* Safe side-channel silent variant, using RSA blinding, and checking the
- * result after CRT. */
+ * result after CRT. In-place calls, with x == m, is allowed. */
int
_rsa_sec_compute_root_tr(const struct rsa_public_key *pub,
const struct rsa_private_key *key,
void *random_ctx, nettle_random_func *random,
- mp_limb_t *x, const mp_limb_t *m, size_t mn);
+ mp_limb_t *x, const mp_limb_t *m);
#endif /* NETTLE_RSA_INTERNAL_H_INCLUDED */
diff --git a/rsa-sec-decrypt.c b/rsa-sec-decrypt.c
index 6866e7c8..fc4757a0 100644
--- a/rsa-sec-decrypt.c
+++ b/rsa-sec-decrypt.c
@@ -58,9 +58,12 @@ rsa_sec_decrypt(const struct rsa_public_key *pub,
TMP_GMP_ALLOC (m, mpz_size(pub->n));
TMP_GMP_ALLOC (em, key->size);
- res = _rsa_sec_compute_root_tr (pub, key, random_ctx, random, m,
- mpz_limbs_read(gibberish),
- mpz_size(gibberish));
+ /* We need a copy because m can be shorter than key_size,
+ * but _rsa_sec_compute_root_tr expect all inputs to be
+ * normalized to a key_size long buffer length */
+ mpz_limbs_copy(m, gibberish, mpz_size(pub->n));
+
+ res = _rsa_sec_compute_root_tr (pub, key, random_ctx, random, m, m);
mpn_get_base256 (em, key->size, m, mpz_size(pub->n));
diff --git a/rsa-sign-tr.c b/rsa-sign-tr.c
index f824c4ca..9e137c7a 100644
--- a/rsa-sign-tr.c
+++ b/rsa-sign-tr.c
@@ -131,35 +131,34 @@ int
_rsa_sec_compute_root_tr(const struct rsa_public_key *pub,
const struct rsa_private_key *key,
void *random_ctx, nettle_random_func *random,
- mp_limb_t *x, const mp_limb_t *m, size_t mn)
+ mp_limb_t *x, const mp_limb_t *m)
{
+ mp_size_t nn;
mpz_t mz;
mpz_t xz;
int res;
- mpz_init(mz);
mpz_init(xz);
- mpn_copyi(mpz_limbs_write(mz, mn), m, mn);
- mpz_limbs_finish(mz, mn);
+ nn = mpz_size (pub->n);
- res = rsa_compute_root_tr(pub, key, random_ctx, random, xz, mz);
+ res = rsa_compute_root_tr(pub, key, random_ctx, random, xz,
+ mpz_roinit_n(mz, m, nn));
if (res)
- mpz_limbs_copy(x, xz, mpz_size(pub->n));
+ mpz_limbs_copy(x, xz, nn);
- mpz_clear(mz);
mpz_clear(xz);
return res;
}
#else
/* Blinds m, by computing c = m r^e (mod n), for a random r. Also
- returns the inverse (ri), for use by rsa_unblind. */
+ returns the inverse (ri), for use by rsa_unblind. Must have c != m,
+ no in-place operation.*/
static void
rsa_sec_blind (const struct rsa_public_key *pub,
void *random_ctx, nettle_random_func *random,
- mp_limb_t *c, mp_limb_t *ri, const mp_limb_t *m,
- mp_size_t mn)
+ mp_limb_t *c, mp_limb_t *ri, const mp_limb_t *m)
{
const mp_limb_t *ep = mpz_limbs_read (pub->e);
const mp_limb_t *np = mpz_limbs_read (pub->n);
@@ -177,15 +176,15 @@ rsa_sec_blind (const struct rsa_public_key *pub,
/* c = m*(r^e) mod n */
itch = mpn_sec_powm_itch(nn, ebn, nn);
- i2 = mpn_sec_mul_itch(nn, mn);
+ i2 = mpn_sec_mul_itch(nn, nn);
itch = MAX(itch, i2);
- i2 = mpn_sec_div_r_itch(nn + mn, nn);
+ i2 = mpn_sec_div_r_itch(2*nn, nn);
itch = MAX(itch, i2);
i2 = mpn_sec_invert_itch(nn);
itch = MAX(itch, i2);
- TMP_GMP_ALLOC (tp, nn + mn + itch);
- scratch = tp + nn + mn;
+ TMP_GMP_ALLOC (tp, 2*nn + itch);
+ scratch = tp + 2*nn;
/* ri = r^(-1) */
do
@@ -198,9 +197,8 @@ rsa_sec_blind (const struct rsa_public_key *pub,
while (!mpn_sec_invert (ri, tp, np, nn, 2 * nn * GMP_NUMB_BITS, scratch));
mpn_sec_powm (c, rp, nn, ep, ebn, np, nn, scratch);
- /* normally mn == nn, but m can be smaller in some cases */
- mpn_sec_mul (tp, c, nn, m, mn, scratch);
- mpn_sec_div_r (tp, nn + mn, np, nn, scratch);
+ mpn_sec_mul (tp, c, nn, m, nn, scratch);
+ mpn_sec_div_r (tp, 2*nn, np, nn, scratch);
mpn_copyi(c, tp, nn);
TMP_GMP_FREE (r);
@@ -208,7 +206,7 @@ rsa_sec_blind (const struct rsa_public_key *pub,
TMP_GMP_FREE (tp);
}
-/* m = c ri mod n */
+/* m = c ri mod n. Allows x == c. */
static void
rsa_sec_unblind (const struct rsa_public_key *pub,
mp_limb_t *x, mp_limb_t *ri, const mp_limb_t *c)
@@ -299,7 +297,7 @@ int
_rsa_sec_compute_root_tr(const struct rsa_public_key *pub,
const struct rsa_private_key *key,
void *random_ctx, nettle_random_func *random,
- mp_limb_t *x, const mp_limb_t *m, size_t mn)
+ mp_limb_t *x, const mp_limb_t *m)
{
TMP_GMP_DECL (c, mp_limb_t);
TMP_GMP_DECL (ri, mp_limb_t);
@@ -307,7 +305,7 @@ _rsa_sec_compute_root_tr(const struct rsa_public_key *pub,
size_t key_limb_size;
int ret;
- key_limb_size = NETTLE_OCTET_SIZE_TO_LIMB_SIZE(key->size);
+ key_limb_size = mpz_size(pub->n);
/* mpz_powm_sec handles only odd moduli. If p, q or n is even, the
key is invalid and rejected by rsa_private_key_prepare. However,
@@ -321,19 +319,18 @@ _rsa_sec_compute_root_tr(const struct rsa_public_key *pub,
}
assert(mpz_size(pub->n) == key_limb_size);
- assert(mn <= key_limb_size);
TMP_GMP_ALLOC (c, key_limb_size);
TMP_GMP_ALLOC (ri, key_limb_size);
TMP_GMP_ALLOC (scratch, _rsa_sec_compute_root_itch(key));
- rsa_sec_blind (pub, random_ctx, random, x, ri, m, mn);
+ rsa_sec_blind (pub, random_ctx, random, c, ri, m);
- _rsa_sec_compute_root(key, c, x, scratch);
+ _rsa_sec_compute_root(key, x, c, scratch);
- ret = rsa_sec_check_root(pub, c, x);
+ ret = rsa_sec_check_root(pub, x, c);
- rsa_sec_unblind(pub, x, ri, c);
+ rsa_sec_unblind(pub, x, ri, x);
cnd_mpn_zero(1 - ret, x, key_limb_size);
@@ -357,17 +354,17 @@ rsa_compute_root_tr(const struct rsa_public_key *pub,
mpz_t x, const mpz_t m)
{
TMP_GMP_DECL (l, mp_limb_t);
+ mp_size_t nn = mpz_size(pub->n);
int res;
- mp_size_t l_size = NETTLE_OCTET_SIZE_TO_LIMB_SIZE(key->size);
- TMP_GMP_ALLOC (l, l_size);
+ TMP_GMP_ALLOC (l, nn);
+ mpz_limbs_copy(l, m, nn);
- res = _rsa_sec_compute_root_tr (pub, key, random_ctx, random, l,
- mpz_limbs_read(m), mpz_size(m));
+ res = _rsa_sec_compute_root_tr (pub, key, random_ctx, random, l, l);
if (res) {
- mp_limb_t *xp = mpz_limbs_write (x, l_size);
- mpn_copyi (xp, l, l_size);
- mpz_limbs_finish (x, l_size);
+ mp_limb_t *xp = mpz_limbs_write (x, nn);
+ mpn_copyi (xp, l, nn);
+ mpz_limbs_finish (x, nn);
}
TMP_GMP_FREE (l);
diff --git a/testsuite/rsa-encrypt-test.c b/testsuite/rsa-encrypt-test.c
index 87525f78..d3bc374b 100644
--- a/testsuite/rsa-encrypt-test.c
+++ b/testsuite/rsa-encrypt-test.c
@@ -19,6 +19,7 @@ test_main(void)
uint8_t after;
mpz_t gibberish;
+ mpz_t zero;
rsa_private_key_init(&key);
rsa_public_key_init(&pub);
@@ -101,6 +102,17 @@ test_main(void)
ASSERT(decrypted[decrypted_length] == after);
ASSERT(decrypted[0] == 'A');
+ /* Test zero input. */
+ mpz_init_set_ui (zero, 0);
+ decrypted_length = msg_length;
+ ASSERT(!rsa_decrypt(&key, &decrypted_length, decrypted, zero));
+ ASSERT(!rsa_decrypt_tr(&pub, &key,
+ &lfib, (nettle_random_func *) knuth_lfib_random,
+ &decrypted_length, decrypted, zero));
+ ASSERT(!rsa_sec_decrypt(&pub, &key,
+ &lfib, (nettle_random_func *) knuth_lfib_random,
+ decrypted_length, decrypted, zero));
+ ASSERT(decrypted_length == msg_length);
/* Test invalid key. */
mpz_add_ui (key.q, key.q, 2);
@@ -112,6 +124,6 @@ test_main(void)
rsa_private_key_clear(&key);
rsa_public_key_clear(&pub);
mpz_clear(gibberish);
+ mpz_clear(zero);
free(decrypted);
}
-
--
2.31.1

163
gnu/packages/patches/nettle-3.5-CVE-2021-3580-pt2.patch 100644
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@ -0,0 +1,163 @@
Copied from upstream nettle git repository.
Removed changes to ChangeLog, to allow this patch to apply to nettle-3.5.
From 0ad0b5df315665250dfdaa4a1e087f4799edaefe Mon Sep 17 00:00:00 2001
From: Niels Möller <nisse@lysator.liu.se>
Date: Mon, 17 May 2021 22:02:47 +0200
Subject: [PATCH 2/2] Add input check to rsa_decrypt family of functions.
---
ChangeLog | 8 ++++++++
rsa-decrypt-tr.c | 4 ++++
rsa-decrypt.c | 10 ++++++++++
rsa-sec-decrypt.c | 4 ++++
rsa.h | 5 +++--
testsuite/rsa-encrypt-test.c | 38 ++++++++++++++++++++++++++++++------
6 files changed, 61 insertions(+), 8 deletions(-)
diff --git a/rsa-decrypt-tr.c b/rsa-decrypt-tr.c
index 927a8915..4a9e9d74 100644
--- a/rsa-decrypt-tr.c
+++ b/rsa-decrypt-tr.c
@@ -52,6 +52,10 @@ rsa_decrypt_tr(const struct rsa_public_key *pub,
mp_size_t key_limb_size;
int res;
+ /* First check that input is in range. */
+ if (mpz_sgn (gibberish) < 0 || mpz_cmp (gibberish, pub->n) >= 0)
+ return 0;
+
key_limb_size = mpz_size(pub->n);
TMP_GMP_ALLOC (m, key_limb_size);
diff --git a/rsa-decrypt.c b/rsa-decrypt.c
index 7681439d..540d8baa 100644
--- a/rsa-decrypt.c
+++ b/rsa-decrypt.c
@@ -48,6 +48,16 @@ rsa_decrypt(const struct rsa_private_key *key,
int res;
mpz_init(m);
+
+ /* First check that input is in range. Since we don't have the
+ public key available here, we need to reconstruct n. */
+ mpz_mul (m, key->p, key->q);
+ if (mpz_sgn (gibberish) < 0 || mpz_cmp (gibberish, m) >= 0)
+ {
+ mpz_clear (m);
+ return 0;
+ }
+
rsa_compute_root(key, m, gibberish);
res = pkcs1_decrypt (key->size, m, length, message);
diff --git a/rsa-sec-decrypt.c b/rsa-sec-decrypt.c
index fc4757a0..4c98958d 100644
--- a/rsa-sec-decrypt.c
+++ b/rsa-sec-decrypt.c
@@ -55,6 +55,10 @@ rsa_sec_decrypt(const struct rsa_public_key *pub,
TMP_GMP_DECL (em, uint8_t);
int res;
+ /* First check that input is in range. */
+ if (mpz_sgn (gibberish) < 0 || mpz_cmp (gibberish, pub->n) >= 0)
+ return 0;
+
TMP_GMP_ALLOC (m, mpz_size(pub->n));
TMP_GMP_ALLOC (em, key->size);
diff --git a/rsa.h b/rsa.h
index 3b10155f..2dd35a2d 100644
--- a/rsa.h
+++ b/rsa.h
@@ -428,13 +428,14 @@ rsa_sec_decrypt(const struct rsa_public_key *pub,
size_t length, uint8_t *message,
const mpz_t gibberish);
-/* Compute x, the e:th root of m. Calling it with x == m is allowed. */
+/* Compute x, the e:th root of m. Calling it with x == m is allowed.
+ It is required that 0 <= m < n. */
void
rsa_compute_root(const struct rsa_private_key *key,
mpz_t x, const mpz_t m);
/* Safer variant, using RSA blinding, and checking the result after
- CRT. */
+ CRT. It is required that 0 <= m < n. */
int
rsa_compute_root_tr(const struct rsa_public_key *pub,
const struct rsa_private_key *key,
diff --git a/testsuite/rsa-encrypt-test.c b/testsuite/rsa-encrypt-test.c
index d3bc374b..d1a440f6 100644
--- a/testsuite/rsa-encrypt-test.c
+++ b/testsuite/rsa-encrypt-test.c
@@ -19,11 +19,12 @@ test_main(void)
uint8_t after;
mpz_t gibberish;
- mpz_t zero;
+ mpz_t bad_input;
rsa_private_key_init(&key);
rsa_public_key_init(&pub);
mpz_init(gibberish);
+ mpz_init(bad_input);
knuth_lfib_init(&lfib, 17);
@@ -103,15 +104,40 @@ test_main(void)
ASSERT(decrypted[0] == 'A');
/* Test zero input. */
- mpz_init_set_ui (zero, 0);
+ mpz_set_ui (bad_input, 0);
decrypted_length = msg_length;
- ASSERT(!rsa_decrypt(&key, &decrypted_length, decrypted, zero));
+ ASSERT(!rsa_decrypt(&key, &decrypted_length, decrypted, bad_input));
ASSERT(!rsa_decrypt_tr(&pub, &key,
&lfib, (nettle_random_func *) knuth_lfib_random,
- &decrypted_length, decrypted, zero));
+ &decrypted_length, decrypted, bad_input));
ASSERT(!rsa_sec_decrypt(&pub, &key,
&lfib, (nettle_random_func *) knuth_lfib_random,
- decrypted_length, decrypted, zero));
+ decrypted_length, decrypted, bad_input));
+ ASSERT(decrypted_length == msg_length);
+
+ /* Test input that is slightly larger than n */
+ mpz_add(bad_input, gibberish, pub.n);
+ decrypted_length = msg_length;
+ ASSERT(!rsa_decrypt(&key, &decrypted_length, decrypted, bad_input));
+ ASSERT(!rsa_decrypt_tr(&pub, &key,
+ &lfib, (nettle_random_func *) knuth_lfib_random,
+ &decrypted_length, decrypted, bad_input));
+ ASSERT(!rsa_sec_decrypt(&pub, &key,
+ &lfib, (nettle_random_func *) knuth_lfib_random,
+ decrypted_length, decrypted, bad_input));
+ ASSERT(decrypted_length == msg_length);
+
+ /* Test input that is considerably larger than n */
+ mpz_mul_2exp (bad_input, pub.n, 100);
+ mpz_add (bad_input, bad_input, gibberish);
+ decrypted_length = msg_length;
+ ASSERT(!rsa_decrypt(&key, &decrypted_length, decrypted, bad_input));
+ ASSERT(!rsa_decrypt_tr(&pub, &key,
+ &lfib, (nettle_random_func *) knuth_lfib_random,
+ &decrypted_length, decrypted, bad_input));
+ ASSERT(!rsa_sec_decrypt(&pub, &key,
+ &lfib, (nettle_random_func *) knuth_lfib_random,
+ decrypted_length, decrypted, bad_input));
ASSERT(decrypted_length == msg_length);
/* Test invalid key. */
@@ -124,6 +150,6 @@ test_main(void)
rsa_private_key_clear(&key);
rsa_public_key_clear(&pub);
mpz_clear(gibberish);
- mpz_clear(zero);
+ mpz_clear(bad_input);
free(decrypted);
}
--
2.31.1

78
gnu/packages/patches/nettle-3.5-check-_pkcs1_sec_decrypt-msg-len.patch 100644
View File

@ -0,0 +1,78 @@
Copied from upstream nettle git repository.
Removed changes to ChangeLog, to allow this patch to apply to nettle-3.5.
From 7616541e6eff73353bf682c62e3a68e4fe696707 Mon Sep 17 00:00:00 2001
From: Niels Möller <nisse@lysator.liu.se>
Date: Thu, 6 May 2021 21:29:56 +0200
Subject: [PATCH] Add check that message length to _pkcs1_sec_decrypt is valid.
* pkcs1-sec-decrypt.c (_pkcs1_sec_decrypt): Check that message
length is valid, for given key size.
* testsuite/rsa-sec-decrypt-test.c (test_main): Add test cases for
calls to rsa_sec_decrypt specifying a too large message length.
---
ChangeLog | 7 +++++++
pkcs1-sec-decrypt.c | 4 +++-
testsuite/rsa-sec-decrypt-test.c | 17 ++++++++++++++++-
3 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/pkcs1-sec-decrypt.c b/pkcs1-sec-decrypt.c
index 4f13080e..16833691 100644
--- a/pkcs1-sec-decrypt.c
+++ b/pkcs1-sec-decrypt.c
@@ -63,7 +63,9 @@ _pkcs1_sec_decrypt (size_t length, uint8_t *message,
volatile int ok;
size_t i, t;
- assert (padded_message_length >= length);
+ /* Message independent branch */
+ if (length + 11 > padded_message_length)
+ return 0;
t = padded_message_length - length - 1;
diff --git a/testsuite/rsa-sec-decrypt-test.c b/testsuite/rsa-sec-decrypt-test.c
index fb0ed3a1..3419322e 100644
--- a/testsuite/rsa-sec-decrypt-test.c
+++ b/testsuite/rsa-sec-decrypt-test.c
@@ -55,6 +55,7 @@ rsa_decrypt_for_test(const struct rsa_public_key *pub,
#endif
#define PAYLOAD_SIZE 50
+#define DECRYPTED_SIZE 256
void
test_main(void)
{
@@ -63,7 +64,7 @@ test_main(void)
struct knuth_lfib_ctx random_ctx;
uint8_t plaintext[PAYLOAD_SIZE];
- uint8_t decrypted[PAYLOAD_SIZE];
+ uint8_t decrypted[DECRYPTED_SIZE];
uint8_t verifybad[PAYLOAD_SIZE];
unsigned n_size = 1024;
mpz_t gibberish;
@@ -99,6 +100,20 @@ test_main(void)
PAYLOAD_SIZE, decrypted, gibberish) == 1);
ASSERT (MEMEQ (PAYLOAD_SIZE, plaintext, decrypted));
+ ASSERT (pub.size > 10);
+ ASSERT (pub.size <= DECRYPTED_SIZE);
+
+ /* Check that too large message length is rejected, largest
+ valid size is pub.size - 11. */
+ ASSERT (!rsa_decrypt_for_test (&pub, &key, &random_ctx,
+ (nettle_random_func *) knuth_lfib_random,
+ pub.size - 10, decrypted, gibberish));
+
+ /* This case used to result in arithmetic underflow and a crash. */
+ ASSERT (!rsa_decrypt_for_test (&pub, &key, &random_ctx,
+ (nettle_random_func *) knuth_lfib_random,
+ pub.size, decrypted, gibberish));
+
/* bad one */
memcpy(decrypted, verifybad, PAYLOAD_SIZE);
nettle_mpz_random_size(garbage, &random_ctx,
--
2.31.1