Fix --tls-version-min and --tls-version-max for OpenSSL 1.1+

As described in <[email protected]...> on the openvpn-devel mailing list, --tls-version-min no longer works with OpenSSL 1.1. Kurt Roeckx posted in a debian bug report:

"This is marked as important because if you switch to openssl 1.1.0 the defaults minimum version in Debian is currently TLS 1.2 and you can't override it with the options that you're currently using (and are deprecated)."

This patch is loosely based on the original patch by Kurt, but solves the issue by adding functions to openssl-compat.h, like we also did for all other openssl 1.1. breakage. This results in not having to add more ifdefs in ssl_openssl.c and thus cleaner code.

Hi Kurt,

Steffan has posted a patch for this that is losely based on yours. It is not merged yet, comments welcome.

https://sourceforge.net/p/openvpn/mailman/openvpn-devel/thread/20171126141555.25930-1-steffan%40karger.me/#msg36136873

Quoted 9 lines

As described in <[email protected]...> on the openvpn-devel mailing list, --tls-version-min no longer works with OpenSSL 1.1. Kurt Roeckx posted in a debian bug report:

"This is marked as important because if you switch to openssl 1.1.0 the defaults minimum version in Debian is currently TLS 1.2 and you can't override it with the options that you're currently using (and are deprecated)."

Quoted 4 lines

This patch is loosely based on the original patch by Kurt, but solves the issue by adding functions to openssl-compat.h, like we also did for all other openssl 1.1. breakage. This results in not having to add more ifdefs in ssl_openssl.c and thus cleaner code.

I have forwarded your patch to Kurt and asked for feedback. See attached mail.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=873302#32

I have some comments:

- It has:

src/openvpn/openssl_compat.h +10 -0

+/* TLS Version defines are new in OpenSSL 1.1 */
+#ifndef TLS1_0_VERSION
+#define TLS1_0_VERSION 0x0301
+#endif
+#ifndef TLS1_1_VERSION
+#define TLS1_1_VERSION 0x0302
+#endif
+#ifndef TLS1_2_VERSION
+#define TLS1_2_VERSION 0x0303
+#endif

It's TLS1_VERSION (not TLS1_0_VERSION)

The defines all exist in at least 1.0.1, the version that added support for TLS 1.1 and 1.2

- It calls SSL_CTX_set_min_proto_version() unconditionally, overriding the library default. In the 1.0.2 case SSLv2 and SSLv3 are then disabled, in the 1.1 case it could enable SSLv3.

- openssl_tls_version() should probably add SSL3_VERSION support.

As described in <[email protected]...> on the openvpn-devel mailing list, --tls-version-min no longer works with OpenSSL 1.1. Kurt Roeckx posted in a debian bug report:

"This is marked as important because if you switch to openssl 1.1.0 the defaults minimum version in Debian is currently TLS 1.2 and you can't override it with the options that you're currently using (and are deprecated)."

This patch is loosely based on the original patch by Kurt, but solves the issue by adding functions to openssl-compat.h, like we also did for all other openssl 1.1. breakage. This results in not having to add more ifdefs in ssl_openssl.c and thus cleaner code.

Signed-off-by Steffan Karger <[email protected]...>

---
v2: fix define name, obey system lib default minimum version

Note: this patch does not cherry-pick to release/2.4 nicely. Once the one for master has been accepted, I'll send a backport for release/2.4.

 src/openvpn/openssl_compat.h | 63 ++++++++++++++++++++++++++++++++
 src/openvpn/ssl_openssl.c    | 86 +++++++++++++++++++++++++-------------------
 2 files changed, 113 insertions(+), 36 deletions(-)

src/openvpn/openssl_compat.h +63 -0

index 70b19aea..2a6c98d9 100644
@@ -647,4 +647,67 @@ EC_GROUP_order_bits(const EC_GROUP *group)
 #define RSA_F_RSA_OSSL_PRIVATE_ENCRYPT       RSA_F_RSA_EAY_PRIVATE_ENCRYPT
 #endif
 
+#ifndef SSL_CTX_get_min_proto_version
+/** Dummy SSL_CTX_get_min_proto_version for OpenSSL < 1.1 (not really needed) */
+static inline int
+SSL_CTX_get_min_proto_version(SSL_CTX *ctx)
+{
+    return 0;
+}
+#endif /* SSL_CTX_get_min_proto_version */
+
+#ifndef SSL_CTX_set_min_proto_version
+/** Mimics SSL_CTX_set_min_proto_version for OpenSSL < 1.1 */
+static inline void
+SSL_CTX_set_min_proto_version(SSL_CTX *ctx, long tls_ver_min)
+{
+    long sslopt = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3; /* Never do < TLS 1.0 */
+
+    if (tls_ver_min > TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_min > TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_min > TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+}
+#endif /* SSL_CTX_set_min_proto_version */
+
+#ifndef SSL_CTX_set_max_proto_version
+/** Mimics SSL_CTX_set_max_proto_version for OpenSSL < 1.1 */
+static inline void
+SSL_CTX_set_max_proto_version(SSL_CTX *ctx, long tls_ver_max)
+{
+    long sslopt = 0;
+
+    if (tls_ver_max < TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_max < TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_max < TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+}
+#endif /* SSL_CTX_set_max_proto_version */
+
 #endif /* OPENSSL_COMPAT_H_ */

src/openvpn/ssl_openssl.c +24 -2

index 34c31b9d..9d5cd5ec 100644
@@ -206,15 +206,56 @@ info_callback(INFO_CALLBACK_SSL_CONST SSL *s, int where, int ret)
 int
 tls_version_max(void)
 {
-#if defined(SSL_OP_NO_TLSv1_2)
+#if defined(TLS1_2_VERSION) || defined(SSL_OP_NO_TLSv1_2)
     return TLS_VER_1_2;
-#elif defined(SSL_OP_NO_TLSv1_1)
+#elif defined(TLS1_1_VERSION) || defined(SSL_OP_NO_TLSv1_1)
     return TLS_VER_1_1;
 #else
     return TLS_VER_1_0;
 #endif
 }
 
+/** Convert internal version number to openssl version number */
+static int
+openssl_tls_version(int ver)
+{
+    if (ver == TLS_VER_1_0)
+    {
+        return TLS1_VERSION;
+    }
+    else if (ver == TLS_VER_1_1)
+    {
+        return TLS1_1_VERSION;
+    }
+    else if (ver == TLS_VER_1_2)
+    {
+        return TLS1_2_VERSION;
+    }
+    return 0;
+}
+
+static void
+tls_ctx_set_tls_versions(struct tls_root_ctx *ctx, unsigned int ssl_flags)
+{

src/openvpn/ssl_openssl.c +6 -32

+    }
+}
+
 void
 tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
 {

@@ -223,42 +264,15 @@ tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
     /* default certificate verification flags */
     int flags = SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
 
-    /* process SSL options including minimum TLS version we will accept from peer */
-    {
-        long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET | SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;
-        int tls_ver_max = TLS_VER_UNSPEC;
-        const int tls_ver_min =
-            (ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT) & SSLF_TLS_VERSION_MIN_MASK;
-
-        tls_ver_max =
-            (ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT) & SSLF_TLS_VERSION_MAX_MASK;
-        if (tls_ver_max <= TLS_VER_UNSPEC)
-        {
-            tls_ver_max = tls_version_max();
-        }
-
-        if (tls_ver_min > TLS_VER_1_0 || tls_ver_max < TLS_VER_1_0)
-        {
-            sslopt |= SSL_OP_NO_TLSv1;
-        }
-#ifdef SSL_OP_NO_TLSv1_1
-        if (tls_ver_min > TLS_VER_1_1 || tls_ver_max < TLS_VER_1_1)
-        {
-            sslopt |= SSL_OP_NO_TLSv1_1;
-        }
-#endif
-#ifdef SSL_OP_NO_TLSv1_2
-        if (tls_ver_min > TLS_VER_1_2 || tls_ver_max < TLS_VER_1_2)
-        {
-            sslopt |= SSL_OP_NO_TLSv1_2;
-        }
-#endif
+    /* process SSL options */
+    long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET;
 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
-        sslopt |= SSL_OP_CIPHER_SERVER_PREFERENCE;
+    sslopt |= SSL_OP_CIPHER_SERVER_PREFERENCE;
 #endif
-        sslopt |= SSL_OP_NO_COMPRESSION;

The patch is good except for some issues that are easy to fix:

Quoted 3 lines · Steffan Karger

As described in <[email protected]...> on the openvpn-devel mailing list, --tls-version-min no longer works with OpenSSL 1.1. Kurt Roeckx posted in a debian bug report:

I did not see this behaviour in locally built openssl 1.1, and so did some digging..

Our current approach still works on stock-built openssl 1.1 (though deprecated). But some distros (e.g., Debian unstable) are patching openssl-1.1 to set TLS 1.2 as the default min version. That can be over-ridden only using the new min/max_proto_version API calls. Debian has recently backed-off on this, but distros restricting TLS versions is something we need to cope with.

Even otherwise directly setting the min/max values is better. And the old and new methods do not work well together. So this change is good to have, independent of the target OS/distro.

Anyway, I want to use this in the cryptoapi patch: why else would anyone do the thankless reviewing job :)

Quoted 134 lines

"This is marked as important because if you switch to openssl 1.1.0 the defaults minimum version in Debian is currently TLS 1.2 and you can't override it with the options that you're currently using (and are deprecated)."

This patch is loosely based on the original patch by Kurt, but solves the issue by adding functions to openssl-compat.h, like we also did for all other openssl 1.1. breakage. This results in not having to add more ifdefs in ssl_openssl.c and thus cleaner code.

Signed-off-by Steffan Karger <[email protected]...>

---
v2: fix define name, obey system lib default minimum version

Note: this patch does not cherry-pick to release/2.4 nicely. Once the one for master has been accepted, I'll send a backport for release/2.4.

 src/openvpn/openssl_compat.h | 63 ++++++++++++++++++++++++++++++++
 src/openvpn/ssl_openssl.c    | 86 +++++++++++++++++++++++++-------------------
 2 files changed, 113 insertions(+), 36 deletions(-)

src/openvpn/openssl_compat.h +63 -0

index 70b19aea..2a6c98d9 100644
@@ -647,4 +647,67 @@ EC_GROUP_order_bits(const EC_GROUP *group)
 #define RSA_F_RSA_OSSL_PRIVATE_ENCRYPT       RSA_F_RSA_EAY_PRIVATE_ENCRYPT
 #endif
 
+#ifndef SSL_CTX_get_min_proto_version
+/** Dummy SSL_CTX_get_min_proto_version for OpenSSL < 1.1 (not really needed) */
+static inline int
+SSL_CTX_get_min_proto_version(SSL_CTX *ctx)
+{
+    return 0;
+}
+#endif /* SSL_CTX_get_min_proto_version */
+
+#ifndef SSL_CTX_set_min_proto_version
+/** Mimics SSL_CTX_set_min_proto_version for OpenSSL < 1.1 */
+static inline void
+SSL_CTX_set_min_proto_version(SSL_CTX *ctx, long tls_ver_min)
+{
+    long sslopt = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3; /* Never do < TLS 1.0 */
+
+    if (tls_ver_min > TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_min > TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_min > TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+}
+#endif /* SSL_CTX_set_min_proto_version */
+
+#ifndef SSL_CTX_set_max_proto_version
+/** Mimics SSL_CTX_set_max_proto_version for OpenSSL < 1.1 */
+static inline void
+SSL_CTX_set_max_proto_version(SSL_CTX *ctx, long tls_ver_max)
+{
+    long sslopt = 0;
+
+    if (tls_ver_max < TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_max < TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_max < TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+}
+#endif /* SSL_CTX_set_max_proto_version */
+
 #endif /* OPENSSL_COMPAT_H_ */

src/openvpn/ssl_openssl.c +24 -2

index 34c31b9d..9d5cd5ec 100644
@@ -206,15 +206,56 @@ info_callback(INFO_CALLBACK_SSL_CONST SSL *s, int where, int ret)
 int
 tls_version_max(void)
 {
-#if defined(SSL_OP_NO_TLSv1_2)
+#if defined(TLS1_2_VERSION) || defined(SSL_OP_NO_TLSv1_2)
     return TLS_VER_1_2;
-#elif defined(SSL_OP_NO_TLSv1_1)
+#elif defined(TLS1_1_VERSION) || defined(SSL_OP_NO_TLSv1_1)
     return TLS_VER_1_1;
 #else
     return TLS_VER_1_0;
 #endif
 }
 
+/** Convert internal version number to openssl version number */
+static int
+openssl_tls_version(int ver)
+{
+    if (ver == TLS_VER_1_0)
+    {
+        return TLS1_VERSION;
+    }
+    else if (ver == TLS_VER_1_1)
+    {
+        return TLS1_1_VERSION;
+    }
+    else if (ver == TLS_VER_1_2)
+    {
+        return TLS1_2_VERSION;
+    }
+    return 0;
+}
+
+static void
+tls_ctx_set_tls_versions(struct tls_root_ctx *ctx, unsigned int ssl_flags)
+{

src/openvpn/ssl_openssl.c info_callback(INFO_CALLBACK_SSL_CONST SSL *s, int where, int ret) · line 249

Quoted 10 lines

src/openvpn/ssl_openssl.c +10 -0

+    int tls_ver_min = openssl_tls_version(
+        (ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT) & SSLF_TLS_VERSION_MIN_MASK);
+    int tls_ver_max = openssl_tls_version(
+        (ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT) & SSLF_TLS_VERSION_MAX_MASK);
+
+    if (!tls_ver_min)
+    {
+        /* Enforce at least TLS 1.0 */
+        int cur_min = SSL_CTX_get_min_proto_version(ctx->ctx);
+        tls_ver_min = cur_min < TLS1_VERSION ? TLS_VER_1_0 : cur_min;

That should be

tls_ver_min = cur_min < TLS1_VERSION ? TLS1_VERSION : cur_min;

src/openvpn/ssl_openssl.c info_callback(INFO_CALLBACK_SSL_CONST SSL *s, int where, int ret) · line 251

Quoted 2 lines

src/openvpn/ssl_openssl.c +2 -0

+    }
+    SSL_CTX_set_min_proto_version(ctx->ctx, tls_ver_min);

This call can potentially fail in openssl 1.1, though unlikely. As a sane minimum is
important, we should check the return value and do something sensible with it. Actually it does fail with the above bug and it could fail in some other convoluted
situations.

src/openvpn/ssl_openssl.c info_callback(INFO_CALLBACK_SSL_CONST SSL *s, int where, int ret) · line 255

Quoted 4 lines

src/openvpn/ssl_openssl.c +4 -0

+
+    if (tls_ver_max)
+    {
+        SSL_CTX_set_max_proto_version(ctx->ctx, tls_ver_max);

This also can potentially fail. Not critical unlike the minimum value, but still a check of the return value and a helpful error message is useful.

Quoted 47 lines

src/openvpn/ssl_openssl.c +6 -32

+    }
+}
+
 void
 tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
 {

@@ -223,42 +264,15 @@ tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
     /* default certificate verification flags */
     int flags = SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
 
-    /* process SSL options including minimum TLS version we will accept from peer */
-    {
-        long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET | SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;
-        int tls_ver_max = TLS_VER_UNSPEC;
-        const int tls_ver_min =
-            (ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT) & SSLF_TLS_VERSION_MIN_MASK;
-
-        tls_ver_max =
-            (ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT) & SSLF_TLS_VERSION_MAX_MASK;
-        if (tls_ver_max <= TLS_VER_UNSPEC)
-        {
-            tls_ver_max = tls_version_max();
-        }
-
-        if (tls_ver_min > TLS_VER_1_0 || tls_ver_max < TLS_VER_1_0)
-        {
-            sslopt |= SSL_OP_NO_TLSv1;
-        }
-#ifdef SSL_OP_NO_TLSv1_1
-        if (tls_ver_min > TLS_VER_1_1 || tls_ver_max < TLS_VER_1_1)
-        {
-            sslopt |= SSL_OP_NO_TLSv1_1;
-        }
-#endif
-#ifdef SSL_OP_NO_TLSv1_2
-        if (tls_ver_min > TLS_VER_1_2 || tls_ver_max < TLS_VER_1_2)
-        {
-            sslopt |= SSL_OP_NO_TLSv1_2;
-        }
-#endif
+    /* process SSL options */
+    long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET;
 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
-        sslopt |= SSL_OP_CIPHER_SERVER_PREFERENCE;
+    sslopt |= SSL_OP_CIPHER_SERVER_PREFERENCE;
 #endif
-        sslopt |= SSL_OP_NO_COMPRESSION;

src/openvpn/ssl_openssl.c tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)

Quoted 10 lines

src/openvpn/ssl_openssl.c +4 -3

-        SSL_CTX_set_options(ctx->ctx, sslopt);
-    }
+    sslopt |= SSL_OP_NO_COMPRESSION;
+    SSL_CTX_set_options(ctx->ctx, sslopt);
+
+    tls_ctx_set_tls_versions(ctx, ssl_flags);
 
 #ifdef SSL_MODE_RELEASE_BUFFERS
     SSL_CTX_set_mode(ctx->ctx, SSL_MODE_RELEASE_BUFFERS);
--

Debian has recently (Nov 2017) back-tracked on setting 1.2 as the default min version, so testing against the original bug report is now hard.

But this passes my tests with custom built openssl and a recently updated debian unstable installation (after the bug fix mentioned above).

Finally, there is a minor issue with openssl 1.1's macros for SSL_CTX_get_min/max_proto_version (long argument passed a NULL) but I think we can live with the compiler warning until they fix it upstream.

As described in <[email protected]...> on the openvpn-devel mailing list, --tls-version-min no longer works with OpenSSL 1.1. Kurt Roeckx posted in a debian bug report:

"This is marked as important because if you switch to openssl 1.1.0 the defaults minimum version in Debian is currently TLS 1.2 and you can't override it with the options that you're currently using (and are deprecated)."

This patch is loosely based on the original patch by Kurt, but solves the issue by adding functions to openssl-compat.h, like we also did for all other openssl 1.1. breakage. This results in not having to add more ifdefs in ssl_openssl.c and thus cleaner code.

Signed-off-by Steffan Karger <[email protected]...>

---
v2: fix define name, obey system lib default minimum version
v3: add error handling, fix bug in setting default minimum

 src/openvpn/openssl_compat.h |  63 +++++++++++++++++++++++++++
 src/openvpn/ssl.c            |   5 ++-
 src/openvpn/ssl_backend.h    |   4 +-
 src/openvpn/ssl_mbedtls.c    |   3 +-
 src/openvpn/ssl_openssl.c    | 100 +++++++++++++++++++++++++++---
-------------
 5 files changed, 136 insertions(+), 39 deletions(-)

src/openvpn/openssl_compat.h +2 -0

index 05ec4e95..4931fad3 100644
@@ -661,4 +661,67 @@ EC_GROUP_order_bits(const EC_GROUP *group)
 #define RSA_F_RSA_OSSL_PRIVATE_ENCRYPT       RSA_F_RSA_EAY_PRIVATE_ENCRYPT
 #endif
 
+#ifndef SSL_CTX_get_min_proto_version
+/** Dummy SSL_CTX_get_min_proto_version for OpenSSL < 1.1 (not really

needed) */

src/openvpn/openssl_compat.h +1 -0

+static inline int

src/openvpn/openssl_compat.h +2 -0

+{
+    long sslopt = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3; /* Never do < TLS

1.0 */

src/openvpn/openssl_compat.h +8 -0

+
+    if (tls_ver_min > TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_min > TLS1_1_VERSION)
+    {

src/openvpn/openssl_compat.h +10 -0

+{
+    long sslopt = 0;
+
+    if (tls_ver_max < TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_max < TLS1_1_VERSION)
+    {

src/openvpn/openssl_compat.h +7 -0

+static int
+openssl_tls_version(int ver)
+{
+    if (ver == TLS_VER_1_0)
+    {
+        return TLS1_VERSION;
+    }

Thanks for the v3.

All good except (sorry to say that :)

The compat versions of SSL_CTX_get_max_proto_version and its min counterpart should return a long or int not void. Assuming we want to continue supporting
openssl 1.0.

This was not an issue earlier when return value was not checked. Anyway, the correct
signature of the 1.1 functions (well macros) it replaces is long.

I should have pointed this out earlier...

There is one more thing that I'm not sure of. See below.

On Fri, Jan 19, 2018 at 2:22 PM, Steffan Karger <[email protected]... <mailto:[email protected]...>> wrote:

As described in <[email protected]... <mailto:[email protected]...>> on the openvpn-devel mailing list, --tls-version-min no longer works with OpenSSL 1.1.  Kurt Roeckx posted in a debian bug report:

"This is marked as important because if you switch to openssl 1.1.0 the defaults minimum version in Debian is currently TLS 1.2 and you can't override it with the options that you're currently using (and are deprecated)."

This patch is loosely based on the original patch by Kurt, but solves the
issue by adding functions to openssl-compat.h, like we also did for all other openssl 1.1. breakage.  This results in not having to add more ifdefs
in ssl_openssl.c and thus cleaner code.

Signed-off-by Steffan Karger <[email protected]...

<mailto:[email protected]...>>
---
v2: fix define name, obey system lib default minimum version
v3: add error handling, fix bug in setting default minimum

 src/openvpn/openssl_compat.h |  63 +++++++++++++++++++++++++++ src/openvpn/ssl.c            |   5 ++- src/openvpn/ssl_backend.h    |   4 +- src/openvpn/ssl_mbedtls.c    |   3 +- src/openvpn/ssl_openssl.c    | 100
+++++++++++++++++++++++++++----------------
 5 files changed, 136 insertions(+), 39 deletions(-)

diff --git a/src/openvpn/openssl_compat.h b/src/openvpn/openssl_compat.h index 05ec4e95..4931fad3 100644
--- a/src/openvpn/openssl_compat.h
+++ b/src/openvpn/openssl_compat.h
@@ -661,4 +661,67 @@ EC_GROUP_order_bits(const EC_GROUP *group) #define RSA_F_RSA_OSSL_PRIVATE_ENCRYPT RSA_F_RSA_EAY_PRIVATE_ENCRYPT
 #endif

+#ifndef SSL_CTX_get_min_proto_version
+/** Dummy SSL_CTX_get_min_proto_version for OpenSSL < 1.1 (not really needed) */
+static inline int +SSL_CTX_get_min_proto_version(SSL_CTX *ctx)
+{
+    return 0;
+}
+#endif /* SSL_CTX_get_min_proto_version */
+
+#ifndef SSL_CTX_set_min_proto_version
+/** Mimics SSL_CTX_set_min_proto_version for OpenSSL < 1.1 */ +static inline void +SSL_CTX_set_min_proto_version(SSL_CTX *ctx, long tls_ver_min)

static inline long (or int)
...

    +{
    +    long sslopt = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3; /* Never do <
    TLS 1.0 */
    +
    +    if (tls_ver_min > TLS1_VERSION)
    +    {
    +        sslopt |= SSL_OP_NO_TLSv1;
    +    }
    +#ifdef SSL_OP_NO_TLSv1_1
    +    if (tls_ver_min > TLS1_1_VERSION)
    +    {
    +        sslopt |= SSL_OP_NO_TLSv1_1;
    +    }
    +#endif
    +#ifdef SSL_OP_NO_TLSv1_2
    +    if (tls_ver_min > TLS1_2_VERSION)
    +    {
    +        sslopt |= SSL_OP_NO_TLSv1_2;
    +    }
    +#endif
    +    SSL_CTX_set_options(ctx, sslopt);

return 1;

+}
+#endif /* SSL_CTX_set_min_proto_version */
+
+#ifndef SSL_CTX_set_max_proto_version
+/** Mimics SSL_CTX_set_max_proto_version for OpenSSL < 1.1 */ +static inline void +SSL_CTX_set_max_proto_version(SSL_CTX *ctx, long tls_ver_max)

static inline long (or int)
...

    +{
    +    long sslopt = 0;
    +
    +    if (tls_ver_max < TLS1_VERSION)
    +    {
    +        sslopt |= SSL_OP_NO_TLSv1;
    +    }
    +#ifdef SSL_OP_NO_TLSv1_1
    +    if (tls_ver_max < TLS1_1_VERSION)
    +    {
    +        sslopt |= SSL_OP_NO_TLSv1_1;
    +    }
    +#endif
    +#ifdef SSL_OP_NO_TLSv1_2
    +    if (tls_ver_max < TLS1_2_VERSION)
    +    {
    +        sslopt |= SSL_OP_NO_TLSv1_2;
    +    }
    +#endif
    +    SSL_CTX_set_options(ctx, sslopt);

return 1;

    +}
    +#endif /* SSL_CTX_set_max_proto_version */0
    +

...

    +/** Convert internal version number to openssl version number */
    +static int
    +openssl_tls_version(int ver)
    +{
    +    if (ver == TLS_VER_1_0)
    +    {
    +        return TLS1_VERSION;
    +    }
    +    else if (ver == TLS_VER_1_1)
    +    {
    +        return TLS1_1_VERSION;
    +    }
    +    else if (ver == TLS_VER_1_2)
    +    {
    +        return TLS1_2_VERSION;
    +    }
    +    return 0;
    +}

TLS1_2_VERSION may not be defined in openssl prior to 1.0.1, would it? Is that a problem? Do we still support 0.9.8 etc? I'm lazy to check this myself.

As described in <[email protected]...> on the openvpn-devel mailing list, --tls-version-min no longer works with OpenSSL 1.1. Kurt Roeckx posted in a debian bug report:

"This is marked as important because if you switch to openssl 1.1.0 the defaults minimum version in Debian is currently TLS 1.2 and you can't override it with the options that you're currently using (and are deprecated)."

This patch is loosely based on the original patch by Kurt, but solves the issue by adding functions to openssl-compat.h, like we also did for all other openssl 1.1. breakage. This results in not having to add more ifdefs in ssl_openssl.c and thus cleaner code.

Signed-off-by Steffan Karger <[email protected]...>

---
v2: fix define name, obey system lib default minimum version
v3: add error handling, fix bug in setting default minimum
v4: also update compat layer for v3 changes

 src/openvpn/openssl_compat.h |  67 +++++++++++++++++++++++++++++
 src/openvpn/ssl.c            |   5 ++-
 src/openvpn/ssl_backend.h    |   4 +-
 src/openvpn/ssl_mbedtls.c    |   3 +-
 src/openvpn/ssl_openssl.c    | 100 +++++++++++++++++++++++++++---
-------------
 5 files changed, 140 insertions(+), 39 deletions(-)

src/openvpn/openssl_compat.h +2 -0

index 05ec4e95..9f1e92a1 100644
@@ -661,4 +661,71 @@ EC_GROUP_order_bits(const EC_GROUP *group)
 #define RSA_F_RSA_OSSL_PRIVATE_ENCRYPT
 RSA_F_RSA_EAY_PRIVATE_ENCRYPT
 #endif
 
+#ifndef SSL_CTX_get_min_proto_version
+/** Dummy SSL_CTX_get_min_proto_version for OpenSSL < 1.1 (not really

needed) */

src/openvpn/openssl_compat.h +13 -0

+static inline int
+SSL_CTX_get_min_proto_version(SSL_CTX *ctx)
+{
+    return 0;
+}
+#endif /* SSL_CTX_get_min_proto_version */
+
+#ifndef SSL_CTX_set_min_proto_version
+/** Mimics SSL_CTX_set_min_proto_version for OpenSSL < 1.1 */
+static inline int
+SSL_CTX_set_min_proto_version(SSL_CTX *ctx, long tls_ver_min)
+{
+    long sslopt = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3; /* Never do < TLS

1.0 */

src/openvpn/openssl_compat.h +52 -0

+
+    if (tls_ver_min > TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_min > TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_min > TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+
+    return 1;
+}
+#endif /* SSL_CTX_set_min_proto_version */
+
+#ifndef SSL_CTX_set_max_proto_version
+/** Mimics SSL_CTX_set_max_proto_version for OpenSSL < 1.1 */
+static inline int
+SSL_CTX_set_max_proto_version(SSL_CTX *ctx, long tls_ver_max)
+{
+    long sslopt = 0;
+
+    if (tls_ver_max < TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_max < TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_max < TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+
+    return 1;
+}
+#endif /* SSL_CTX_set_max_proto_version */
+
 #endif /* OPENSSL_COMPAT_H_ */

src/openvpn/ssl.c +4 -1

index 7b428455..6c27050f 100644
@@ -622,7 +622,10 @@ init_ssl(const struct options *options, struct
 tls_root_ctx *new_ctx)
      * cipher restrictions before loading certificates */
     tls_ctx_restrict_ciphers(new_ctx, options->cipher_list);
 
-    tls_ctx_set_options(new_ctx, options->ssl_flags);
+    if (!tls_ctx_set_options(new_ctx, options->ssl_flags))
+    {
+        goto err;
+    }
 
     if (options->pkcs12_file)

     {

src/openvpn/ssl_backend.h +3 -1

index 7cf5d830..444fb2f9 100644
@@ -162,8 +162,10 @@ bool tls_ctx_initialised(struct tls_root_ctx *ctx);
  *
  * @param ctx           TLS context to set options on
  * @param ssl_flags     SSL flags to set
+ *
+ * @return true on success, false otherwise.
  */
-void tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int
 ssl_flags);
+bool tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int
 ssl_flags);
 

/**
* Restrict the list of ciphers that can be used within the TLS context.

src/openvpn/ssl_mbedtls.c +2 -1

index 8ac52d55..d503162a 100644
@@ -206,9 +206,10 @@ key_state_export_keying_material(struct
 key_state_ssl *ssl,
 {
 }
 
-void
+bool
 tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
 {
+    return true;
 }
 

static const char *

src/openvpn/ssl_openssl.c +28 -3

index 86318d4c..50d68280 100644
@@ -206,16 +206,65 @@ info_callback(INFO_CALLBACK_SSL_CONST SSL *s, int
 where, int ret)
 int
 tls_version_max(void)
 {
-#if defined(SSL_OP_NO_TLSv1_2)
+#if defined(TLS1_2_VERSION) || defined(SSL_OP_NO_TLSv1_2)
     return TLS_VER_1_2;
-#elif defined(SSL_OP_NO_TLSv1_1)
+#elif defined(TLS1_1_VERSION) || defined(SSL_OP_NO_TLSv1_1)
     return TLS_VER_1_1;
 #else
     return TLS_VER_1_0;
 #endif
 }
 
-void
+/** Convert internal version number to openssl version number */
+static int
+openssl_tls_version(int ver)
+{
+    if (ver == TLS_VER_1_0)
+    {
+        return TLS1_VERSION;
+    }
+    else if (ver == TLS_VER_1_1)
+    {
+        return TLS1_1_VERSION;
+    }
+    else if (ver == TLS_VER_1_2)
+    {
+        return TLS1_2_VERSION;
+    }
+    return 0;
+}
+
+static bool
+tls_ctx_set_tls_versions(struct tls_root_ctx *ctx, unsigned int
 ssl_flags)
+{
+    int tls_ver_min = openssl_tls_version(
+        (ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT) &
 SSLF_TLS_VERSION_MIN_MASK);
+    int tls_ver_max = openssl_tls_version(
+        (ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT) &

SSLF_TLS_VERSION_MAX_MASK);

src/openvpn/ssl_openssl.c +11 -0

+
+    if (!tls_ver_min)
+    {
+        /* Enforce at least TLS 1.0 */
+        int cur_min = SSL_CTX_get_min_proto_version(ctx->ctx);
+        tls_ver_min = cur_min < TLS1_VERSION ? TLS1_VERSION : cur_min;
+    }
+
+    if (!SSL_CTX_set_min_proto_version(ctx->ctx, tls_ver_min))
+    {
+        msg(D_TLS_ERRORS, "%s: failed to set minimum TLS version",

__func__);

src/openvpn/ssl_openssl.c +4 -0

+        return false;
+    }
+
+    if (tls_ver_max && !SSL_CTX_set_max_proto_version(ctx->ctx,

tls_ver_max))

src/openvpn/ssl_openssl.c +2 -0

+    {
+        msg(D_TLS_ERRORS, "%s: failed to set maximum TLS version",

__func__);

src/openvpn/ssl_openssl.c +7 -1

+        return false;
+    }
+
+    return true;
+}
+
+bool
 tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
 {
     ASSERT(NULL != ctx);

@@ -223,41 +272,18 @@ tls_ctx_set_options(struct tls_root_ctx *ctx,
 unsigned int ssl_flags)
     /* default certificate verification flags */
     int flags = SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
 
-    /* process SSL options including minimum TLS version we will accept

from peer */

src/openvpn/ssl_openssl.c +0 -2

-    {
-        long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET |

SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;

src/openvpn/ssl_openssl.c +0 -3

-        int tls_ver_max = TLS_VER_UNSPEC;
-        const int tls_ver_min =
-            (ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT) &

SSLF_TLS_VERSION_MIN_MASK;

src/openvpn/ssl_openssl.c +0 -3

-
-        tls_ver_max =
-            (ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT) &

SSLF_TLS_VERSION_MAX_MASK;

src/openvpn/ssl_openssl.c +10 -24

-        if (tls_ver_max <= TLS_VER_UNSPEC)
-        {
-            tls_ver_max = tls_version_max();
-        }
-
-        if (tls_ver_min > TLS_VER_1_0 || tls_ver_max < TLS_VER_1_0)
-        {
-            sslopt |= SSL_OP_NO_TLSv1;
-        }
-#ifdef SSL_OP_NO_TLSv1_1
-        if (tls_ver_min > TLS_VER_1_1 || tls_ver_max < TLS_VER_1_1)
-        {
-            sslopt |= SSL_OP_NO_TLSv1_1;
-        }
-#endif
-#ifdef SSL_OP_NO_TLSv1_2
-        if (tls_ver_min > TLS_VER_1_2 || tls_ver_max < TLS_VER_1_2)
-        {
-            sslopt |= SSL_OP_NO_TLSv1_2;
-        }
-#endif
+    /* process SSL options */
+    long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET;
 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
-        sslopt |= SSL_OP_CIPHER_SERVER_PREFERENCE;
+    sslopt |= SSL_OP_CIPHER_SERVER_PREFERENCE;
 #endif
-        sslopt |= SSL_OP_NO_COMPRESSION;
-        SSL_CTX_set_options(ctx->ctx, sslopt);
+    sslopt |= SSL_OP_NO_COMPRESSION;
+
+    SSL_CTX_set_options(ctx->ctx, sslopt);
+
+    if (!tls_ctx_set_tls_versions(ctx, ssl_flags))
+    {
+        return false;
     }
 
 #ifdef SSL_MODE_RELEASE_BUFFERS

Hi,

Thanks for last and final v4 :)

Quoted 297 lines · Steffan Karger

As described in <[email protected]...> on the openvpn-devel mailing list, --tls-version-min no longer works with OpenSSL 1.1. Kurt Roeckx posted in a debian bug report:

"This is marked as important because if you switch to openssl 1.1.0 the defaults minimum version in Debian is currently TLS 1.2 and you can't override it with the options that you're currently using (and are deprecated)."

This patch is loosely based on the original patch by Kurt, but solves the issue by adding functions to openssl-compat.h, like we also did for all other openssl 1.1. breakage. This results in not having to add more ifdefs in ssl_openssl.c and thus cleaner code.

Signed-off-by Steffan Karger <[email protected]...>

---
v2: fix define name, obey system lib default minimum version
v3: add error handling, fix bug in setting default minimum
v4: also update compat layer for v3 changes

  src/openvpn/openssl_compat.h |  67 +++++++++++++++++++++++++++++
  src/openvpn/ssl.c            |   5 ++-
  src/openvpn/ssl_backend.h    |   4 +-
  src/openvpn/ssl_mbedtls.c    |   3 +-
  src/openvpn/ssl_openssl.c    | 100 +++++++++++++++++++++++++++---
-------------
  5 files changed, 140 insertions(+), 39 deletions(-)

src/openvpn/openssl_compat.h +2 -0

index 05ec4e95..9f1e92a1 100644
@@ -661,4 +661,71 @@ EC_GROUP_order_bits(const EC_GROUP *group)
  #define RSA_F_RSA_OSSL_PRIVATE_ENCRYPT
  RSA_F_RSA_EAY_PRIVATE_ENCRYPT
  #endif
 
+#ifndef SSL_CTX_get_min_proto_version
+/** Dummy SSL_CTX_get_min_proto_version for OpenSSL < 1.1 (not really

needed) */

src/openvpn/openssl_compat.h +13 -0

+static inline int
+SSL_CTX_get_min_proto_version(SSL_CTX *ctx)
+{
+    return 0;
+}
+#endif /* SSL_CTX_get_min_proto_version */
+
+#ifndef SSL_CTX_set_min_proto_version
+/** Mimics SSL_CTX_set_min_proto_version for OpenSSL < 1.1 */
+static inline int
+SSL_CTX_set_min_proto_version(SSL_CTX *ctx, long tls_ver_min)
+{
+    long sslopt = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3; /* Never do < TLS

1.0 */

src/openvpn/openssl_compat.h +52 -0

+
+    if (tls_ver_min > TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_min > TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_min > TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+
+    return 1;
+}
+#endif /* SSL_CTX_set_min_proto_version */
+
+#ifndef SSL_CTX_set_max_proto_version
+/** Mimics SSL_CTX_set_max_proto_version for OpenSSL < 1.1 */
+static inline int
+SSL_CTX_set_max_proto_version(SSL_CTX *ctx, long tls_ver_max)
+{
+    long sslopt = 0;
+
+    if (tls_ver_max < TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_max < TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_max < TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+
+    return 1;
+}
+#endif /* SSL_CTX_set_max_proto_version */
+
  #endif /* OPENSSL_COMPAT_H_ */

src/openvpn/ssl.c +4 -1

index 7b428455..6c27050f 100644
@@ -622,7 +622,10 @@ init_ssl(const struct options *options, struct
 tls_root_ctx *new_ctx)
       * cipher restrictions before loading certificates */
      tls_ctx_restrict_ciphers(new_ctx, options->cipher_list);
 
-    tls_ctx_set_options(new_ctx, options->ssl_flags);
+    if (!tls_ctx_set_options(new_ctx, options->ssl_flags))
+    {
+        goto err;
+    }
 
      if (options->pkcs12_file)

      {

src/openvpn/ssl_backend.h +3 -1

index 7cf5d830..444fb2f9 100644
@@ -162,8 +162,10 @@ bool tls_ctx_initialised(struct tls_root_ctx *ctx);
   *
   * @param ctx           TLS context to set options on
   * @param ssl_flags     SSL flags to set
+ *
+ * @return true on success, false otherwise.
   */
-void tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int
 ssl_flags);
+bool tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int
 ssl_flags);
 

/**
* Restrict the list of ciphers that can be used within the TLS context.

src/openvpn/ssl_mbedtls.c +2 -1

index 8ac52d55..d503162a 100644
@@ -206,9 +206,10 @@ key_state_export_keying_material(struct
 key_state_ssl *ssl,
  {
  }
 
-void
+bool
  tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
  {
+    return true;
  }
 

static const char *

src/openvpn/ssl_openssl.c +28 -3

index 86318d4c..50d68280 100644
@@ -206,16 +206,65 @@ info_callback(INFO_CALLBACK_SSL_CONST SSL *s, int
 where, int ret)
  int
  tls_version_max(void)
  {
-#if defined(SSL_OP_NO_TLSv1_2)
+#if defined(TLS1_2_VERSION) || defined(SSL_OP_NO_TLSv1_2)
      return TLS_VER_1_2;
-#elif defined(SSL_OP_NO_TLSv1_1)
+#elif defined(TLS1_1_VERSION) || defined(SSL_OP_NO_TLSv1_1)
      return TLS_VER_1_1;
  #else
      return TLS_VER_1_0;
  #endif
  }
 
-void
+/** Convert internal version number to openssl version number */
+static int
+openssl_tls_version(int ver)
+{
+    if (ver == TLS_VER_1_0)
+    {
+        return TLS1_VERSION;
+    }
+    else if (ver == TLS_VER_1_1)
+    {
+        return TLS1_1_VERSION;
+    }
+    else if (ver == TLS_VER_1_2)
+    {
+        return TLS1_2_VERSION;
+    }
+    return 0;
+}
+
+static bool
+tls_ctx_set_tls_versions(struct tls_root_ctx *ctx, unsigned int
 ssl_flags)
+{
+    int tls_ver_min = openssl_tls_version(
+        (ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT) &
 SSLF_TLS_VERSION_MIN_MASK);
+    int tls_ver_max = openssl_tls_version(
+        (ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT) &

SSLF_TLS_VERSION_MAX_MASK);

src/openvpn/ssl_openssl.c +11 -0

+
+    if (!tls_ver_min)
+    {
+        /* Enforce at least TLS 1.0 */
+        int cur_min = SSL_CTX_get_min_proto_version(ctx->ctx);
+        tls_ver_min = cur_min < TLS1_VERSION ? TLS1_VERSION : cur_min;
+    }
+
+    if (!SSL_CTX_set_min_proto_version(ctx->ctx, tls_ver_min))
+    {
+        msg(D_TLS_ERRORS, "%s: failed to set minimum TLS version",

__func__);

src/openvpn/ssl_openssl.c +4 -0

+        return false;
+    }
+
+    if (tls_ver_max && !SSL_CTX_set_max_proto_version(ctx->ctx,

tls_ver_max))

src/openvpn/ssl_openssl.c +2 -0

+    {
+        msg(D_TLS_ERRORS, "%s: failed to set maximum TLS version",

__func__);

src/openvpn/ssl_openssl.c +7 -1

+        return false;
+    }
+
+    return true;
+}
+
+bool
  tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
  {
      ASSERT(NULL != ctx);

@@ -223,41 +272,18 @@ tls_ctx_set_options(struct tls_root_ctx *ctx,
 unsigned int ssl_flags)
      /* default certificate verification flags */
      int flags = SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
 
-    /* process SSL options including minimum TLS version we will accept

from peer */

src/openvpn/ssl_openssl.c +0 -2

-    {
-        long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET |

SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;

src/openvpn/ssl_openssl.c +0 -3

-        int tls_ver_max = TLS_VER_UNSPEC;
-        const int tls_ver_min =
-            (ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT) &

SSLF_TLS_VERSION_MIN_MASK;

src/openvpn/ssl_openssl.c +0 -3

-
-        tls_ver_max =
-            (ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT) &

SSLF_TLS_VERSION_MAX_MASK;

src/openvpn/ssl_openssl.c +10 -24

-        if (tls_ver_max <= TLS_VER_UNSPEC)
-        {
-            tls_ver_max = tls_version_max();
-        }
-
-        if (tls_ver_min > TLS_VER_1_0 || tls_ver_max < TLS_VER_1_0)
-        {
-            sslopt |= SSL_OP_NO_TLSv1;
-        }
-#ifdef SSL_OP_NO_TLSv1_1
-        if (tls_ver_min > TLS_VER_1_1 || tls_ver_max < TLS_VER_1_1)
-        {
-            sslopt |= SSL_OP_NO_TLSv1_1;
-        }
-#endif
-#ifdef SSL_OP_NO_TLSv1_2
-        if (tls_ver_min > TLS_VER_1_2 || tls_ver_max < TLS_VER_1_2)
-        {
-            sslopt |= SSL_OP_NO_TLSv1_2;
-        }
-#endif
+    /* process SSL options */
+    long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET;
  #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
-        sslopt |= SSL_OP_CIPHER_SERVER_PREFERENCE;
+    sslopt |= SSL_OP_CIPHER_SERVER_PREFERENCE;
  #endif
-        sslopt |= SSL_OP_NO_COMPRESSION;
-        SSL_CTX_set_options(ctx->ctx, sslopt);
+    sslopt |= SSL_OP_NO_COMPRESSION;
+
+    SSL_CTX_set_options(ctx->ctx, sslopt);
+
+    if (!tls_ctx_set_tls_versions(ctx, ssl_flags))
+    {
+        return false;
      }
 
  #ifdef SSL_MODE_RELEASE_BUFFERS

src/openvpn/ssl_openssl.c tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned · line 313

Quoted 8 lines

src/openvpn/ssl_openssl.c +2 -0

@@ -280,6 +306,8 @@ tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned
 int ssl_flags)
      SSL_CTX_set_verify(ctx->ctx, flags, verify_callback);
 
      SSL_CTX_set_info_callback(ctx->ctx, info_callback);
+
+    return true;
  }
 

Now I can tease patchwork by

Acked-by Selva Nair <[email protected]...>

Reviewed-by Selva Nair <[email protected]...>

Tested-by Selva Nair <[email protected]...>