Document rollback issues.

[openssl.git] / ssl / s23_srvr.c

diff --git a/ssl/s23_srvr.c b/ssl/s23_srvr.c
index 49320647e7033e93ec4da90f34f6a91866c4307f..a81544a1b62a99a15f54cfa2960ca97d3bb6580a 100644 (file)
--- a/ssl/s23_srvr.c
+++ b/ssl/s23_srvr.c
@@ -189,9 +189,10 @@ end:
 int ssl23_get_client_hello(SSL *s)
        {
        char buf_space[11]; /* Request this many bytes in initial read.
-                            * We can detect SSL 3.0/TLS 1.0 Client Hellos only
-                            * when the following is in a single record
-                            * (not guaranteed by protocol specs):
+                            * We can detect SSL 3.0/TLS 1.0 Client Hellos
+                            * ('type == 3') correctly only when the following
+                            * is in a single record, which is not guaranteed by
+                            * the protocol specification:
                             * Byte  Content
                             *  0     type            \
                             *  1/2   version          > record header
@@ -200,14 +201,16 @@ int ssl23_get_client_hello(SSL *s)
                             *  6-8   length           > Client Hello message
                             *  9/10  client_version  /
                             */
-/* XXX */
        char *buf= &(buf_space[0]);
        unsigned char *p,*d,*dd;
        unsigned int i;
        unsigned int csl,sil,cl;
        int n=0,j;
-       int type=0,use_sslv2_strong=0;
+       int type=0;
        int v[2];
+#ifndef NO_RSA
+       int use_sslv2_strong=0;
+#endif
 
        if (s->state == SSL23_ST_SR_CLNT_HELLO_A)
                {
@@ -294,7 +297,7 @@ int ssl23_get_client_hello(SSL *s)
                                        if (n <= 0) return(n);
                                        p=s->packet;
 
-                                       if ((buf=Malloc(n)) == NULL)
+                                       if ((buf=OPENSSL_malloc(n)) == NULL)
                                                {
                                                SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,ERR_R_MALLOC_FAILURE);
                                                goto err;
@@ -338,14 +341,23 @@ int ssl23_get_client_hello(SSL *s)
                else if ((p[0] == SSL3_RT_HANDSHAKE) &&
                         (p[1] == SSL3_VERSION_MAJOR) &&
                         (p[5] == SSL3_MT_CLIENT_HELLO) &&
-                        (p[9] == p[1]))
+                        ((p[3] == 0 && p[4] < 5 /* silly record length? */)
+                               || (p[9] == p[1])))
                        {
                        /*
                         * SSLv3 or tls1 header
                         */
                        
-                       /* we must look at client_version inside the client hello: */
-                       v[0]=p[9]; v[1]=p[10];
+                       v[0]=p[1]; /* major version */
+                       /* We must look at client_version inside the Client Hello message
+                        * to get the correct minor version: */
+                       v[1]=p[10];
+                       /* However if we have only a pathologically small fragment of the
+                        * Client Hello message, we simply use the version from the
+                        * record header -- this is incorrect but unlikely to fail in
+                        * practice */
+                       if (p[3] == 0 && p[4] < 6)
+                               v[1]=p[2];
                        if (v[1] >= TLS1_VERSION_MINOR)
                                {
                                if (!(s->options & SSL_OP_NO_TLSv1))
@@ -380,7 +392,6 @@ int ssl23_get_client_hello(SSL *s)
                        }
                }
 
-next_bit:
        if (s->state == SSL23_ST_SR_CLNT_HELLO_B)
                {
                /* we have SSLv3/TLSv1 in an SSLv2 header
@@ -484,9 +495,12 @@ next_bit:
 
                s->state=SSL2_ST_GET_CLIENT_HELLO_A;
                if ((s->options & SSL_OP_MSIE_SSLV2_RSA_PADDING) ||
-                       use_sslv2_strong)
+                       use_sslv2_strong ||
+                       (s->options & SSL_OP_NO_TLSv1 && s->options & SSL_OP_NO_SSLv3))
                        s->s2->ssl2_rollback=0;
                else
+                       /* reject SSL 2.0 session if client supports SSL 3.0 or TLS 1.0
+                        * (SSL 3.0 draft/RFC 2246, App. E.2) */
                        s->s2->ssl2_rollback=1;
 
                /* setup the n bytes we have read so we get them from
@@ -548,10 +562,10 @@ next_bit:
                }
        s->init_num=0;
 
-       if (buf != buf_space) Free(buf);
+       if (buf != buf_space) OPENSSL_free(buf);
        s->first_packet=1;
        return(SSL_accept(s));
 err:
-       if (buf != buf_space) Free(buf);
+       if (buf != buf_space) OPENSSL_free(buf);
        return(-1);
        }