OpenSSL CVE-2016-2177, CVE-2016-2178

OpenSSL CVE-2016-2177, CVE-2016-2178

[Leo Famulari]

Some bugs in OpenSSL were recently disclosed.

CVE-2016-2177
http://seclists.org/oss-sec/2016/q2/500

CVE-2016-2178
http://seclists.org/oss-sec/2016/q2/493

The second bug can apparently be used by an attacker to recover DSA
keys. And remember that OpenSSH uses OpenSSL, so it is affected too.

Should we try cherry-picking the upstream commits from the OpenSSL
development repo?

Re: OpenSSL CVE-2016-2177, CVE-2016-2178

[Ludovic Courtès]

Leo Famulari <leo@famulari.name> skribis:

> Some bugs in OpenSSL were recently disclosed.
>
> CVE-2016-2177
> http://seclists.org/oss-sec/2016/q2/500
>
> CVE-2016-2178
> http://seclists.org/oss-sec/2016/q2/493
>
> The second bug can apparently be used by an attacker to recover DSA
> keys. And remember that OpenSSH uses OpenSSL, so it is affected too.
>
> Should we try cherry-picking the upstream commits from the OpenSSL
> development repo?

Sounds like it.  Could you look into it?

Thanks for the heads-up!

Ludo’.

Re: OpenSSL CVE-2016-2177, CVE-2016-2178

[Leo Famulari]

[-- Attachment #1.1: Type: text/plain, Size: 990 bytes --]

On Sun, Jun 12, 2016 at 10:49:23PM +0200, Ludovic Courtès wrote:
> Leo Famulari <leo@famulari.name> skribis:
> > CVE-2016-2177
> > http://seclists.org/oss-sec/2016/q2/500
> >
> > CVE-2016-2178
> > http://seclists.org/oss-sec/2016/q2/493
> >
> > Should we try cherry-picking the upstream commits from the OpenSSL
> > development repo?
> 
> Sounds like it.  Could you look into it?

I've attached my patch.

According to OpenSSL's security policy [0], they seem to consider these
bugs to be "LOW severity", since they did not keep them private or issue
a new release, or even an advisory [1].

There is also some discussion of the severity in this thread:
http://seclists.org/oss-sec/2016/q2/493

So, perhaps it's not worth the risk of cherry-picking these commits out
of context, at least not without asking the upstream maintainers.

Thoughts?

[0]
https://www.openssl.org/policies/secpolicy.html

[1]
https://www.openssl.org/news/vulnerabilities.html#y2016

[-- Attachment #1.2: 0001-gnu-openssl-Fix-CVE-2016-2177-and-CVE-2016-2178.patch --]
[-- Type: text/x-diff, Size: 15459 bytes --]

From 93e120f46b60bb3b87e33711ef4a9342b66bca21 Mon Sep 17 00:00:00 2001
From: Leo Famulari <leo@famulari.name>
Date: Mon, 13 Jun 2016 16:15:34 -0400
Subject: [PATCH] gnu: openssl: Fix CVE-2016-2177 and CVE-2016-2178.

* gnu/packages/patches/openssl-CVE-2016-2177.patch,
gnu/packages/patches/openssl-CVE-2016-2178.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/tls.scm (openssl/fixed): Use them.
---
 gnu/local.mk                                     |   2 +
 gnu/packages/patches/openssl-CVE-2016-2177.patch | 286 +++++++++++++++++++++++
 gnu/packages/patches/openssl-CVE-2016-2178.patch | 112 +++++++++
 gnu/packages/tls.scm                             |   4 +-
 4 files changed, 403 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/openssl-CVE-2016-2177.patch
 create mode 100644 gnu/packages/patches/openssl-CVE-2016-2178.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index 73aef0a..9d642ba 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -686,6 +686,8 @@ dist_patch_DATA =						\
   %D%/packages/patches/openssh-CVE-2015-8325.patch		\
   %D%/packages/patches/openssl-runpath.patch			\
   %D%/packages/patches/openssl-c-rehash-in.patch		\
+  %D%/packages/patches/openssl-CVE-2016-2177.patch		\
+  %D%/packages/patches/openssl-CVE-2016-2178.patch		\
   %D%/packages/patches/orpheus-cast-errors-and-includes.patch	\
   %D%/packages/patches/ots-no-include-missing-file.patch	\
   %D%/packages/patches/patchelf-page-size.patch			\
diff --git a/gnu/packages/patches/openssl-CVE-2016-2177.patch b/gnu/packages/patches/openssl-CVE-2016-2177.patch
new file mode 100644
index 0000000..f6465ae
--- /dev/null
+++ b/gnu/packages/patches/openssl-CVE-2016-2177.patch
@@ -0,0 +1,286 @@
+Fix CVE-2016-2177.
+
+<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2177>
+
+Source:
+<https://git.openssl.org/?p=openssl.git;a=commit;h=a004e72b95835136d3f1ea90517f706c24c03da7>
+
+From a004e72b95835136d3f1ea90517f706c24c03da7 Mon Sep 17 00:00:00 2001
+From: Matt Caswell <matt@openssl.org>
+Date: Thu, 5 May 2016 11:10:26 +0100
+Subject: [PATCH] Avoid some undefined pointer arithmetic
+
+A common idiom in the codebase is:
+
+if (p + len > limit)
+{
+    return; /* Too long */
+}
+
+Where "p" points to some malloc'd data of SIZE bytes and
+limit == p + SIZE
+
+"len" here could be from some externally supplied data (e.g. from a TLS
+message).
+
+The rules of C pointer arithmetic are such that "p + len" is only well
+defined where len <= SIZE. Therefore the above idiom is actually
+undefined behaviour.
+
+For example this could cause problems if some malloc implementation
+provides an address for "p" such that "p + len" actually overflows for
+values of len that are too big and therefore p + len < limit!
+
+Issue reported by Guido Vranken.
+
+CVE-2016-2177
+
+Reviewed-by: Rich Salz <rsalz@openssl.org>
+---
+ ssl/s3_srvr.c  | 14 +++++++-------
+ ssl/ssl_sess.c |  2 +-
+ ssl/t1_lib.c   | 56 ++++++++++++++++++++++++++++++--------------------------
+ 3 files changed, 38 insertions(+), 34 deletions(-)
+
+diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
+index ab28702..ab7f690 100644
+--- a/ssl/s3_srvr.c
++++ b/ssl/s3_srvr.c
+@@ -980,7 +980,7 @@ int ssl3_get_client_hello(SSL *s)
+ 
+         session_length = *(p + SSL3_RANDOM_SIZE);
+ 
+-        if (p + SSL3_RANDOM_SIZE + session_length + 1 >= d + n) {
++        if (SSL3_RANDOM_SIZE + session_length + 1 >= (d + n) - p) {
+             al = SSL_AD_DECODE_ERROR;
+             SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+             goto f_err;
+@@ -998,7 +998,7 @@ int ssl3_get_client_hello(SSL *s)
+     /* get the session-id */
+     j = *(p++);
+ 
+-    if (p + j > d + n) {
++    if ((d + n) - p < j) {
+         al = SSL_AD_DECODE_ERROR;
+         SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+         goto f_err;
+@@ -1054,14 +1054,14 @@ int ssl3_get_client_hello(SSL *s)
+ 
+     if (SSL_IS_DTLS(s)) {
+         /* cookie stuff */
+-        if (p + 1 > d + n) {
++        if ((d + n) - p < 1) {
+             al = SSL_AD_DECODE_ERROR;
+             SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+             goto f_err;
+         }
+         cookie_len = *(p++);
+ 
+-        if (p + cookie_len > d + n) {
++        if ((d + n ) - p < cookie_len) {
+             al = SSL_AD_DECODE_ERROR;
+             SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+             goto f_err;
+@@ -1131,7 +1131,7 @@ int ssl3_get_client_hello(SSL *s)
+         }
+     }
+ 
+-    if (p + 2 > d + n) {
++    if ((d + n ) - p < 2) {
+         al = SSL_AD_DECODE_ERROR;
+         SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+         goto f_err;
+@@ -1145,7 +1145,7 @@ int ssl3_get_client_hello(SSL *s)
+     }
+ 
+     /* i bytes of cipher data + 1 byte for compression length later */
+-    if ((p + i + 1) > (d + n)) {
++    if ((d + n) - p < i + 1) {
+         /* not enough data */
+         al = SSL_AD_DECODE_ERROR;
+         SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_MISMATCH);
+@@ -1211,7 +1211,7 @@ int ssl3_get_client_hello(SSL *s)
+ 
+     /* compression */
+     i = *(p++);
+-    if ((p + i) > (d + n)) {
++    if ((d + n) - p < i) {
+         /* not enough data */
+         al = SSL_AD_DECODE_ERROR;
+         SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_MISMATCH);
+diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c
+index b182998..54ee783 100644
+--- a/ssl/ssl_sess.c
++++ b/ssl/ssl_sess.c
+@@ -573,7 +573,7 @@ int ssl_get_prev_session(SSL *s, unsigned char *session_id, int len,
+     int r;
+ #endif
+ 
+-    if (session_id + len > limit) {
++    if (limit - session_id < len) {
+         fatal = 1;
+         goto err;
+     }
+diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
+index fb64607..cdac011 100644
+--- a/ssl/t1_lib.c
++++ b/ssl/t1_lib.c
+@@ -1867,11 +1867,11 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
+         0x02, 0x03,             /* SHA-1/ECDSA */
+     };
+ 
+-    if (data >= (limit - 2))
++    if (limit - data <= 2)
+         return;
+     data += 2;
+ 
+-    if (data > (limit - 4))
++    if (limit - data < 4)
+         return;
+     n2s(data, type);
+     n2s(data, size);
+@@ -1879,7 +1879,7 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
+     if (type != TLSEXT_TYPE_server_name)
+         return;
+ 
+-    if (data + size > limit)
++    if (limit - data < size)
+         return;
+     data += size;
+ 
+@@ -1887,7 +1887,7 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
+         const size_t len1 = sizeof(kSafariExtensionsBlock);
+         const size_t len2 = sizeof(kSafariTLS12ExtensionsBlock);
+ 
+-        if (data + len1 + len2 != limit)
++        if (limit - data != (int)(len1 + len2))
+             return;
+         if (memcmp(data, kSafariExtensionsBlock, len1) != 0)
+             return;
+@@ -1896,7 +1896,7 @@ static void ssl_check_for_safari(SSL *s, const unsigned char *data,
+     } else {
+         const size_t len = sizeof(kSafariExtensionsBlock);
+ 
+-        if (data + len != limit)
++        if (limit - data != (int)(len))
+             return;
+         if (memcmp(data, kSafariExtensionsBlock, len) != 0)
+             return;
+@@ -2053,19 +2053,19 @@ static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p,
+     if (data == limit)
+         goto ri_check;
+ 
+-    if (data > (limit - 2))
++    if (limit - data < 2)
+         goto err;
+ 
+     n2s(data, len);
+ 
+-    if (data + len != limit)
++    if (limit - data != len)
+         goto err;
+ 
+-    while (data <= (limit - 4)) {
++    while (limit - data >= 4) {
+         n2s(data, type);
+         n2s(data, size);
+ 
+-        if (data + size > (limit))
++        if (limit - data < size)
+             goto err;
+ # if 0
+         fprintf(stderr, "Received extension type %d size %d\n", type, size);
+@@ -2472,18 +2472,18 @@ static int ssl_scan_clienthello_custom_tlsext(SSL *s,
+     if (s->hit || s->cert->srv_ext.meths_count == 0)
+         return 1;
+ 
+-    if (data >= limit - 2)
++    if (limit - data <= 2)
+         return 1;
+     n2s(data, len);
+ 
+-    if (data > limit - len)
++    if (limit - data < len)
+         return 1;
+ 
+-    while (data <= limit - 4) {
++    while (limit - data >= 4) {
+         n2s(data, type);
+         n2s(data, size);
+ 
+-        if (data + size > limit)
++        if (limit - data < size)
+             return 1;
+         if (custom_ext_parse(s, 1 /* server */ , type, data, size, al) <= 0)
+             return 0;
+@@ -2569,20 +2569,20 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
+                              SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
+ # endif
+ 
+-    if (data >= (d + n - 2))
++    if ((d + n) - data <= 2)
+         goto ri_check;
+ 
+     n2s(data, length);
+-    if (data + length != d + n) {
++    if ((d + n) - data != length) {
+         *al = SSL_AD_DECODE_ERROR;
+         return 0;
+     }
+ 
+-    while (data <= (d + n - 4)) {
++    while ((d + n) - data >= 4) {
+         n2s(data, type);
+         n2s(data, size);
+ 
+-        if (data + size > (d + n))
++        if ((d + n) - data < size)
+             goto ri_check;
+ 
+         if (s->tlsext_debug_cb)
+@@ -3307,29 +3307,33 @@ int tls1_process_ticket(SSL *s, unsigned char *session_id, int len,
+     /* Skip past DTLS cookie */
+     if (SSL_IS_DTLS(s)) {
+         i = *(p++);
+-        p += i;
+-        if (p >= limit)
++
++        if (limit - p <= i)
+             return -1;
++
++        p += i;
+     }
+     /* Skip past cipher list */
+     n2s(p, i);
+-    p += i;
+-    if (p >= limit)
++    if (limit - p <= i)
+         return -1;
++    p += i;
++
+     /* Skip past compression algorithm list */
+     i = *(p++);
+-    p += i;
+-    if (p > limit)
++    if (limit - p < i)
+         return -1;
++    p += i;
++
+     /* Now at start of extensions */
+-    if ((p + 2) >= limit)
++    if (limit - p <= 2)
+         return 0;
+     n2s(p, i);
+-    while ((p + 4) <= limit) {
++    while (limit - p >= 4) {
+         unsigned short type, size;
+         n2s(p, type);
+         n2s(p, size);
+-        if (p + size > limit)
++        if (limit - p < size)
+             return 0;
+         if (type == TLSEXT_TYPE_session_ticket) {
+             int r;
+-- 
+2.8.4
+
diff --git a/gnu/packages/patches/openssl-CVE-2016-2178.patch b/gnu/packages/patches/openssl-CVE-2016-2178.patch
new file mode 100644
index 0000000..37cf276
--- /dev/null
+++ b/gnu/packages/patches/openssl-CVE-2016-2178.patch
@@ -0,0 +1,112 @@
+Fix CVE-2016-2178.
+
+<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2178>
+
+Source:
+<https://git.openssl.org/?p=openssl.git;a=commit;h=621eaf49a289bfac26d4cbcdb7396e796784c534>
+<https://git.openssl.org/?p=openssl.git;a=commit;h=b7d0f2834e139a20560d64c73e2565e93715ce2b>
+
+From 621eaf49a289bfac26d4cbcdb7396e796784c534 Mon Sep 17 00:00:00 2001
+From: Cesar Pereida <cesar.pereida@aalto.fi>
+Date: Mon, 23 May 2016 12:45:25 +0300
+Subject: [PATCH 1/2] Fix DSA, preserve BN_FLG_CONSTTIME
+
+Operations in the DSA signing algorithm should run in constant time in
+order to avoid side channel attacks. A flaw in the OpenSSL DSA
+implementation means that a non-constant time codepath is followed for
+certain operations. This has been demonstrated through a cache-timing
+attack to be sufficient for an attacker to recover the private DSA key.
+
+CVE-2016-2178
+
+Reviewed-by: Richard Levitte <levitte@openssl.org>
+Reviewed-by: Matt Caswell <matt@openssl.org>
+---
+ crypto/dsa/dsa_ossl.c | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/crypto/dsa/dsa_ossl.c b/crypto/dsa/dsa_ossl.c
+index efc4f1b..b29eb4b 100644
+--- a/crypto/dsa/dsa_ossl.c
++++ b/crypto/dsa/dsa_ossl.c
+@@ -248,9 +248,6 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
+         if (!BN_rand_range(&k, dsa->q))
+             goto err;
+     while (BN_is_zero(&k)) ;
+-    if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
+-        BN_set_flags(&k, BN_FLG_CONSTTIME);
+-    }
+ 
+     if (dsa->flags & DSA_FLAG_CACHE_MONT_P) {
+         if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p,
+@@ -279,9 +276,12 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
+         }
+ 
+         K = &kq;
++
++        BN_set_flags(K, BN_FLG_CONSTTIME);
+     } else {
+         K = &k;
+     }
++
+     DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx,
+                    dsa->method_mont_p);
+     if (!BN_mod(r, r, dsa->q, ctx))
+-- 
+2.8.4
+
+From b7d0f2834e139a20560d64c73e2565e93715ce2b Mon Sep 17 00:00:00 2001
+From: Matt Caswell <matt@openssl.org>
+Date: Tue, 7 Jun 2016 09:12:51 +0100
+Subject: [PATCH 2/2] More fix DSA, preserve BN_FLG_CONSTTIME
+
+The previous "fix" still left "k" exposed to constant time problems in
+the later BN_mod_inverse() call. Ensure both k and kq have the
+BN_FLG_CONSTTIME flag set at the earliest opportunity after creation.
+
+CVE-2016-2178
+
+Reviewed-by: Rich Salz <rsalz@openssl.org>
+---
+ crypto/dsa/dsa_ossl.c | 11 ++++++++---
+ 1 file changed, 8 insertions(+), 3 deletions(-)
+
+diff --git a/crypto/dsa/dsa_ossl.c b/crypto/dsa/dsa_ossl.c
+index b29eb4b..58013a4 100644
+--- a/crypto/dsa/dsa_ossl.c
++++ b/crypto/dsa/dsa_ossl.c
+@@ -247,7 +247,12 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
+     do
+         if (!BN_rand_range(&k, dsa->q))
+             goto err;
+-    while (BN_is_zero(&k)) ;
++    while (BN_is_zero(&k));
++
++    if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
++        BN_set_flags(&k, BN_FLG_CONSTTIME);
++    }
++
+ 
+     if (dsa->flags & DSA_FLAG_CACHE_MONT_P) {
+         if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p,
+@@ -261,6 +266,8 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
+         if (!BN_copy(&kq, &k))
+             goto err;
+ 
++        BN_set_flags(&kq, BN_FLG_CONSTTIME);
++
+         /*
+          * We do not want timing information to leak the length of k, so we
+          * compute g^k using an equivalent exponent of fixed length. (This
+@@ -276,8 +283,6 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
+         }
+ 
+         K = &kq;
+-
+-        BN_set_flags(K, BN_FLG_CONSTTIME);
+     } else {
+         K = &k;
+     }
+-- 
+2.8.4
+
diff --git a/gnu/packages/tls.scm b/gnu/packages/tls.scm
index e543a7e..513edcc 100644
--- a/gnu/packages/tls.scm
+++ b/gnu/packages/tls.scm
@@ -316,7 +316,9 @@ required structures.")
           (base32
            "06996ds1rk8xhnyb5y273a7xkcxhggp4bq1g02rab55d7bjhfh0x"))
          (patches (search-patches "openssl-runpath.patch"
-                                  "openssl-c-rehash-in.patch")))))))
+                                  "openssl-c-rehash-in.patch"
+                                  "openssl-CVE-2016-2177.patch"
+                                  "openssl-CVE-2016-2178.patch")))))))
 
 (define-public libressl
   (package
-- 
2.8.4


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Re: OpenSSL CVE-2016-2177, CVE-2016-2178

[Ludovic Courtès]

Leo Famulari <leo@famulari.name> skribis:

> On Sun, Jun 12, 2016 at 10:49:23PM +0200, Ludovic Courtès wrote:
>> Leo Famulari <leo@famulari.name> skribis:
>> > CVE-2016-2177
>> > http://seclists.org/oss-sec/2016/q2/500
>> >
>> > CVE-2016-2178
>> > http://seclists.org/oss-sec/2016/q2/493
>> >
>> > Should we try cherry-picking the upstream commits from the OpenSSL
>> > development repo?
>> 
>> Sounds like it.  Could you look into it?
>
> I've attached my patch.
>
> According to OpenSSL's security policy [0], they seem to consider these
> bugs to be "LOW severity", since they did not keep them private or issue
> a new release, or even an advisory [1].
>
> There is also some discussion of the severity in this thread:
> http://seclists.org/oss-sec/2016/q2/493
>
> So, perhaps it's not worth the risk of cherry-picking these commits out
> of context, at least not without asking the upstream maintainers.
>
> Thoughts?

I don’t feel qualified to judge the severity of the bug (they do seem
hard to exploit, but I’m no expert.)

Since you’ve already done the work, I think we should simply apply those
fixes.

Makes sense?

Thank you!

Ludo’.

Re: OpenSSL CVE-2016-2177, CVE-2016-2178

[Leo Famulari]

On Tue, Jun 14, 2016 at 02:13:25PM +0200, Ludovic Courtès wrote:
> Since you’ve already done the work, I think we should simply apply those
> fixes.

Applied as 9c4a8514d