Fix protocol downgrade bug in case of fragmented packets
[openssl.git] / ssl / s23_srvr.c
index 9d5481cd0e020c07a150cf04f70e4a76411c2b41..484a1a6e262fb98a60bcfb307227ca4329fb3779 100644 (file)
 #include <openssl/rand.h>
 #include <openssl/objects.h>
 #include <openssl/evp.h>
+#ifdef OPENSSL_FIPS
+#include <openssl/fips.h>
+#endif
 
 static const SSL_METHOD *ssl23_get_server_method(int ver);
 int ssl23_get_client_hello(SSL *s);
@@ -128,6 +131,10 @@ static const SSL_METHOD *ssl23_get_server_method(int ver)
                return(SSLv3_server_method());
        else if (ver == TLS1_VERSION)
                return(TLSv1_server_method());
+       else if (ver == TLS1_1_VERSION)
+               return(TLSv1_1_server_method());
+       else if (ver == TLS1_2_VERSION)
+               return(TLSv1_2_server_method());
        else
                return(NULL);
        }
@@ -283,7 +290,20 @@ int ssl23_get_client_hello(SSL *s)
                                /* SSLv3/TLSv1 */
                                if (p[4] >= TLS1_VERSION_MINOR)
                                        {
-                                       if (!(s->options & SSL_OP_NO_TLSv1))
+                                       if (p[4] >= TLS1_2_VERSION_MINOR &&
+                                          !(s->options & SSL_OP_NO_TLSv1_2))
+                                               {
+                                               s->version=TLS1_2_VERSION;
+                                               s->state=SSL23_ST_SR_CLNT_HELLO_B;
+                                               }
+                                       else if (p[4] >= TLS1_1_VERSION_MINOR &&
+                                          !(s->options & SSL_OP_NO_TLSv1_1))
+                                               {
+                                               s->version=TLS1_1_VERSION;
+                                               /* type=2; */ /* done later to survive restarts */
+                                               s->state=SSL23_ST_SR_CLNT_HELLO_B;
+                                               }
+                                       else if (!(s->options & SSL_OP_NO_TLSv1))
                                                {
                                                s->version=TLS1_VERSION;
                                                /* type=2; */ /* done later to survive restarts */
@@ -315,7 +335,7 @@ int ssl23_get_client_hello(SSL *s)
                         (p[1] == SSL3_VERSION_MAJOR) &&
                         (p[5] == SSL3_MT_CLIENT_HELLO) &&
                         ((p[3] == 0 && p[4] < 5 /* silly record length? */)
-                               || (p[9] == p[1])))
+                               || (p[9] >= p[1])))
                        {
                        /*
                         * SSLv3 or tls1 header
@@ -328,22 +348,37 @@ int ssl23_get_client_hello(SSL *s)
                         * Client Hello message, this would be difficult, and we'd have
                         * to read more records to find out.
                         * No known SSL 3.0 client fragments ClientHello like this,
-                        * so we simply assume TLS 1.0 to avoid protocol version downgrade
-                        * attacks. */
+                        * so we simply reject such connections to avoid
+                        * protocol version downgrade attacks. */
                        if (p[3] == 0 && p[4] < 6)
                                {
-#if 0
                                SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,SSL_R_RECORD_TOO_SMALL);
                                goto err;
-#else
-                               v[1] = TLS1_VERSION_MINOR;
-#endif
                                }
+                       /* if major version number > 3 set minor to a value
+                        * which will use the highest version 3 we support.
+                        * If TLS 2.0 ever appears we will need to revise
+                        * this....
+                        */
+                       if (p[9] > SSL3_VERSION_MAJOR)
+                               v[1]=0xff;
                        else
                                v[1]=p[10]; /* minor version according to client_version */
                        if (v[1] >= TLS1_VERSION_MINOR)
                                {
-                               if (!(s->options & SSL_OP_NO_TLSv1))
+                               if (v[1] >= TLS1_2_VERSION_MINOR &&
+                                       !(s->options & SSL_OP_NO_TLSv1_2))
+                                       {
+                                       s->version=TLS1_2_VERSION;
+                                       type=3;
+                                       }
+                               else if (v[1] >= TLS1_1_VERSION_MINOR &&
+                                       !(s->options & SSL_OP_NO_TLSv1_1))
+                                       {
+                                       s->version=TLS1_1_VERSION;
+                                       type=3;
+                                       }
+                               else if (!(s->options & SSL_OP_NO_TLSv1))
                                        {
                                        s->version=TLS1_VERSION;
                                        type=3;
@@ -386,6 +421,28 @@ int ssl23_get_client_hello(SSL *s)
                        }
                }
 
+       if (s->version < TLS1_2_VERSION && tls1_suiteb(s))
+               {
+               SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,
+                               SSL_R_ONLY_TLS_1_2_ALLOWED_IN_SUITEB_MODE);
+               goto err;
+               }
+
+#ifdef OPENSSL_FIPS
+       if (FIPS_mode() && (s->version < TLS1_VERSION))
+               {
+               SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,
+                                       SSL_R_ONLY_TLS_ALLOWED_IN_FIPS_MODE);
+               goto err;
+               }
+#endif
+
+       if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL))
+               {
+               SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,SSL_R_VERSION_TOO_LOW);
+               goto err;
+               }
+
        if (s->state == SSL23_ST_SR_CLNT_HELLO_B)
                {
                /* we have SSLv3/TLSv1 in an SSLv2 header
@@ -396,14 +453,34 @@ int ssl23_get_client_hello(SSL *s)
                v[0] = p[3]; /* == SSL3_VERSION_MAJOR */
                v[1] = p[4];
 
+               /* An SSLv3/TLSv1 backwards-compatible CLIENT-HELLO in an SSLv2
+                * header is sent directly on the wire, not wrapped as a TLS
+                * record. It's format is:
+                * Byte  Content
+                * 0-1   msg_length
+                * 2     msg_type
+                * 3-4   version
+                * 5-6   cipher_spec_length
+                * 7-8   session_id_length
+                * 9-10  challenge_length
+                * ...   ...
+                */
                n=((p[0]&0x7f)<<8)|p[1];
                if (n > (1024*4))
                        {
                        SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,SSL_R_RECORD_TOO_LARGE);
                        goto err;
                        }
+               if (n < 9)
+                       {
+                       SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,SSL_R_RECORD_LENGTH_MISMATCH);
+                       goto err;
+                       }
 
                j=ssl23_read_bytes(s,n+2);
+               /* We previously read 11 bytes, so if j > 0, we must have
+                * j == n+2 == s->packet_length. We have at least 11 valid
+                * packet bytes. */
                if (j <= 0) return(j);
 
                ssl3_finish_mac(s, s->packet+2, s->packet_length-2);
@@ -560,8 +637,11 @@ int ssl23_get_client_hello(SSL *s)
                        s->s3->rbuf.left=0;
                        s->s3->rbuf.offset=0;
                        }
-
-               if (s->version == TLS1_VERSION)
+               if (s->version == TLS1_2_VERSION)
+                       s->method = TLSv1_2_server_method();
+               else if (s->version == TLS1_1_VERSION)
+                       s->method = TLSv1_1_server_method();
+               else if (s->version == TLS1_VERSION)
                        s->method = TLSv1_server_method();
                else
                        s->method = SSLv3_server_method();