1 files changed, 172 insertions, 0 deletions

diff --git a/src/lib/libssl/ssl_versions.c b/src/lib/libssl/ssl_versions.c
new file mode 100644
index 0000000000..415d935fa5
--- /dev/null
+++ b/src/lib/libssl/ssl_versions.c
@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "ssl_locl.h"
+
+static int
+ssl_clamp_version_range(uint16_t *min_ver, uint16_t *max_ver,
+    uint16_t clamp_min, uint16_t clamp_max)
+{
+        if (clamp_min > clamp_max || *min_ver > *max_ver)
+                return 0;
+        if (clamp_max < *min_ver || clamp_min > *max_ver)
+                return 0;
+
+        if (*min_ver < clamp_min)
+                *min_ver = clamp_min;
+        if (*max_ver > clamp_max)
+                *max_ver = clamp_max;
+
+        return 1;
+}
+
+int
+ssl_enabled_version_range(SSL *s, uint16_t *min_ver, uint16_t *max_ver)
+{
+        uint16_t min_version, max_version;
+
+        /*
+         * The enabled versions have to be a contiguous range, which means we
+         * cannot enable and disable single versions at our whim, even though
+         * this is what the OpenSSL flags allow. The historical way this has
+         * been handled is by making a flag mean that all higher versions
+         * are disabled, if any version lower than the flag is enabled.
+         */
+
+        min_version = 0;
+        max_version = TLS1_2_VERSION;
+
+        if ((s->internal->options & SSL_OP_NO_TLSv1) == 0)
+                min_version = TLS1_VERSION;
+        else if ((s->internal->options & SSL_OP_NO_TLSv1_1) == 0)
+                min_version = TLS1_1_VERSION;
+        else if ((s->internal->options & SSL_OP_NO_TLSv1_2) == 0)
+                min_version = TLS1_2_VERSION;
+
+        if ((s->internal->options & SSL_OP_NO_TLSv1_2) && min_version < TLS1_2_VERSION)
+                max_version = TLS1_1_VERSION;
+        if ((s->internal->options & SSL_OP_NO_TLSv1_1) && min_version < TLS1_1_VERSION)
+                max_version = TLS1_VERSION;
+        if ((s->internal->options & SSL_OP_NO_TLSv1) && min_version < TLS1_VERSION)
+                max_version = 0;
+
+        /* Everything has been disabled... */
+        if (min_version == 0 || max_version == 0)
+                return 0;
+
+        /* Limit to configured version range. */
+        if (!ssl_clamp_version_range(&min_version, &max_version,
+            s->internal->min_version, s->internal->max_version))
+                return 0;
+
+        if (min_ver != NULL)
+                *min_ver = min_version;
+        if (max_ver != NULL)
+                *max_ver = max_version;
+
+        return 1;
+}
+
+int
+ssl_supported_version_range(SSL *s, uint16_t *min_ver, uint16_t *max_ver)
+{
+        uint16_t min_version, max_version;
+
+        /* DTLS cannot currently be disabled... */
+        if (SSL_IS_DTLS(s)) {
+                min_version = max_version = DTLS1_VERSION;
+                goto done;
+        }
+
+        if (!ssl_enabled_version_range(s, &min_version, &max_version))
+                return 0;
+
+        /* Limit to the versions supported by this method. */
+        if (!ssl_clamp_version_range(&min_version, &max_version,
+            s->method->internal->min_version,
+            s->method->internal->max_version))
+                return 0;
+
+ done:
+        if (min_ver != NULL)
+                *min_ver = min_version;
+        if (max_ver != NULL)
+                *max_ver = max_version;
+
+        return 1;
+}
+
+int
+ssl_max_shared_version(SSL *s, uint16_t peer_ver, uint16_t *max_ver)
+{
+        uint16_t min_version, max_version, shared_version;
+
+        *max_ver = 0;
+
+        if (SSL_IS_DTLS(s)) {
+                if (peer_ver >= DTLS1_VERSION) {
+                        *max_ver = DTLS1_VERSION;
+                        return 1;
+                }
+                return 0;
+        }
+
+        if (peer_ver >= TLS1_2_VERSION)
+                shared_version = TLS1_2_VERSION;
+        else if (peer_ver >= TLS1_1_VERSION)
+                shared_version = TLS1_1_VERSION;
+        else if (peer_ver >= TLS1_VERSION)
+                shared_version = TLS1_VERSION;
+        else
+                return 0;
+
+        if (!ssl_supported_version_range(s, &min_version, &max_version))
+                return 0;
+
+        if (shared_version < min_version)
+                return 0;
+
+        if (shared_version > max_version)
+                shared_version = max_version;
+
+        *max_ver = shared_version;
+
+        return 1;
+}
+
+uint16_t
+ssl_max_server_version(SSL *s)
+{
+        uint16_t max_version, min_version = 0;
+
+        if (SSL_IS_DTLS(s))
+                return (DTLS1_VERSION);
+
+        if (!ssl_enabled_version_range(s, &min_version, &max_version))
+                return 0;
+
+        /*
+         * Limit to the versions supported by this method. The SSL method
+         * will be changed during version negotiation, as such we want to
+         * use the SSL method from the context.
+         */
+        if (!ssl_clamp_version_range(&min_version, &max_version,
+            s->ctx->method->internal->min_version,
+            s->ctx->method->internal->max_version))
+                return 0;
+
+        return (max_version);
+}