Clean up some of the SSL server code.

CHANGES

@@ -4,6 +4,11 @@
 
  Changes between 0.9.4 and 0.9.5  [xx XXX 1999]
 
+  *) Rewrite ssl3_read_n (ssl/s3_pkt.c) avoiding a couple of bugs,
+     including a possible buffer overflow when the 'read_ahead'
+     flag is set.
+     [Bodo Moeller]
+
   *) New function X509_CTX_rget_chain(), this returns the chain
      from an X509_CTX structure with a dup of the stack and all
      the X509 reference counts upped: so the stack will exist

ssl/s23_srvr.c

@@ -186,7 +186,18 @@ end:
 
 int ssl23_get_client_hello(SSL *s)
 	{
-	char buf_space[11]; /* request this many bytes in initial read */
+	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):
+	                     * Byte  Content
+	                     *  0     type            \
+	                     *  1/2   version          > record header
+	                     *  3/4   length          /
+	                     *  5     msg_type        \
+	                     *  6-8   length           > Client Hello message
+	                     *  9/10  client_version  /
+	                     */
 	char *buf= &(buf_space[0]);
 	unsigned char *p,*d,*dd;
 	unsigned int i;

ssl/s3_pkt.c

@@ -55,6 +55,59 @@
  * copied and put under another distribution licence
  * [including the GNU Public Licence.]
  */
+/* ====================================================================
+ * Copyright (c) 1998-1999 The OpenSSL Project.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer. 
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    openssl-core@openssl.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com).  This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com).
+ *
+ */
 
 #include <stdio.h>
 #include <errno.h>
@@ -71,104 +124,91 @@ static int ssl3_get_record(SSL *s);
 static int do_compress(SSL *ssl);
 static int do_uncompress(SSL *ssl);
 static int do_change_cipher_spec(SSL *ssl);
+
 static int ssl3_read_n(SSL *s, int n, int max, int extend)
 	{
+	/* If extend == 0, obtain new n-byte packet; if extend == 1, increase
+	 * packet by another n bytes.
+	 * The packet will be in the sub-array of s->s3->rbuf.buf specified
+	 * by s->packet and s->packet_length.
+	 * (If s->read_ahead is set, 'max' bytes may be stored in rbuf
+	 * [plus s->packet_length bytes if extend == 1].)
+	 */
 	int i,off,newb;
 
-	/* if there is stuff still in the buffer from a previous read,
+	if (!extend)
-	 * and there is more than we want, take some. */
+		{
+		/* start with empty packet ... */
+		if (s->s3->rbuf.left == 0)
+			s->s3->rbuf.offset = 0;
+		s->packet = s->s3->rbuf.buf + s->s3->rbuf.offset;
+		s->packet_length = 0;
+		/* ... now we can act as if 'extend' was set */
+		}
+
+	/* if there is enough in the buffer from a previous read, take some */
 	if (s->s3->rbuf.left >= (int)n)
 		{
-		if (extend)
+		s->packet_length+=n;
-			s->packet_length+=n;
-		else
-			{
-			s->packet= &(s->s3->rbuf.buf[s->s3->rbuf.offset]);
-			s->packet_length=n;
-			}
 		s->s3->rbuf.left-=n;
 		s->s3->rbuf.offset+=n;
 		return(n);
 		}
 
 	/* else we need to read more data */
-	if (!s->read_ahead) max=n;
+	if (!s->read_ahead)
-	if (max > SSL3_RT_MAX_PACKET_SIZE)
+		max=n;
-		max=SSL3_RT_MAX_PACKET_SIZE;
 
-	/* First check if there is some left or we want to extend */
+	{
-	off=0;
+		/* avoid buffer overflow */
-	if (	(s->s3->rbuf.left != 0) ||
+		int max_max = SSL3_RT_MAX_PACKET_SIZE - s->packet_length;
-		((s->packet_length != 0) && extend))
+		if (s->options & SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER)
+			max_max += SSL3_RT_MAX_EXTRA;
+		if (max > max_max)
+			max = max_max;
+	}
+
+	off = s->packet_length;
+	newb = s->s3->rbuf.left;
+	/* Move any available bytes to front of buffer:
+	 * 'off' bytes already pointed to by 'packet',
+	 * 'newb' extra ones at the end */
+	if (s->packet != s->s3->rbuf.buf)
 		{
-		newb=s->s3->rbuf.left;
+		/*  off > 0 */
-		if (extend)
+		memmove(s->s3->rbuf.buf, s->packet, off+newb);
-			{
+		s->packet = s->s3->rbuf.buf;
-			/* Copy bytes back to the front of the buffer 
-			 * Take the bytes already pointed to by 'packet'
-			 * and take the extra ones on the end. */
-			off=s->packet_length;
-			if (s->packet != s->s3->rbuf.buf)
-				memcpy(s->s3->rbuf.buf,s->packet,newb+off);
-			}
-		else if (s->s3->rbuf.offset != 0)
-			{ /* so the data is not at the start of the buffer */
-			memcpy(s->s3->rbuf.buf,
-				&(s->s3->rbuf.buf[s->s3->rbuf.offset]),newb);
-			s->s3->rbuf.offset=0;
-			}
-
-		s->s3->rbuf.left=0;
 		}
-	else
+	
-		newb=0;
-
-	/* So we now have 'newb' bytes at the front of 
-	 * s->s3->rbuf.buf and need to read some more in on the end
-	 * We start reading into the buffer at 's->s3->rbuf.offset'
-	 */
-	s->packet=s->s3->rbuf.buf;
-
 	while (newb < n)
 		{
+		/* Now we have off+newb bytes at the front of s->s3->rbuf.buf and need
+		 * to read in more until we have off+n (up to off+max if possible) */
+
 		clear_sys_error();
 		if (s->rbio != NULL)
 			{
 			s->rwstate=SSL_READING;
-			i=BIO_read(s->rbio,
+			i=BIO_read(s->rbio,	&(s->s3->rbuf.buf[off+newb]), max-newb);
-				(char *)&(s->s3->rbuf.buf[off+newb]),
-				max-newb);
 			}
 		else
 			{
 			SSLerr(SSL_F_SSL3_READ_N,SSL_R_READ_BIO_NOT_SET);
-			i= -1;
+			i = -1;
 			}
 
 		if (i <= 0)
 			{
-			s->s3->rbuf.left+=newb;
+			s->s3->rbuf.left = newb;
 			return(i);
 			}
 		newb+=i;
 		}
 
-	/* record used data read */
+	/* done reading, now the book-keeping */
-	if (newb > n)
+	s->s3->rbuf.offset = off + n;
-		{
+	s->s3->rbuf.left = newb - n;
-		s->s3->rbuf.offset=n+off;
+	s->packet_length += n;
-		s->s3->rbuf.left=newb-n;
-		}
-	else
-		{
-		s->s3->rbuf.offset=0;
-		s->s3->rbuf.left=0;
-		}
-
-	if (extend)
-		s->packet_length+=n;
-	else
-		s->packet_length+=n;
 	return(n);
 	}
 
@@ -176,8 +216,8 @@ static int ssl3_read_n(SSL *s, int n, int max, int extend)
  * It will return <= 0 if more data is needed, normally due to an error
  * or non-blocking IO.
  * When it finishes, one packet has been decoded and can be found in
- * ssl->s3->rrec.type	- is the type of record
+ * ssl->s3->rrec.type    - is the type of record
- * ssl->s3->rrec.data, 	- data
+ * ssl->s3->rrec.data, 	 - data
  * ssl->s3->rrec.length, - number of bytes
  */
 static int ssl3_get_record(SSL *s)
@@ -262,7 +302,6 @@ again:
 		if (rr->length > (s->packet_length-SSL3_RT_HEADER_LENGTH))
 			{
 			i=rr->length;
-			/*-(s->packet_length-SSL3_RT_HEADER_LENGTH); */
 			n=ssl3_read_n(s,i,i,1);
 			if (n <= 0) return(n); /* error or non-blocking io */
 			}
@@ -645,7 +684,7 @@ int ssl3_read_bytes(SSL *s, int type, unsigned char *buf, int len)
 	void (*cb)()=NULL;
 	BIO *bio;
 
-	if (s->s3->rbuf.buf == NULL) /* Not initialize yet */
+	if (s->s3->rbuf.buf == NULL) /* Not initialized yet */
 		if (!ssl3_setup_buffers(s))
 			return(-1);
 
@@ -662,10 +701,10 @@ int ssl3_read_bytes(SSL *s, int type, unsigned char *buf, int len)
 start:
 	s->rwstate=SSL_NOTHING;
 
-	/* s->s3->rrec.type	- is the type of record
+	/* s->s3->rrec.type	    - is the type of record
-	 * s->s3->rrec.data, 	- data
+	 * s->s3->rrec.data,    - data
-	 * s->s3->rrec.off, 	- ofset into 'data' for next read
+	 * s->s3->rrec.off,     - offset into 'data' for next read
-	 * s->s3->rrec.length,	- number of bytes. */
+	 * s->s3->rrec.length,  - number of bytes. */
 	rr= &(s->s3->rrec);
 
 	/* get new packet */
@@ -692,16 +731,16 @@ start:
 		return(0);
 		}
 
-	/* Check for an incoming 'Client Request' message */
+	/* Check for an incoming 'Hello Request' message from client */
 	if ((rr->type == SSL3_RT_HANDSHAKE) && (rr->length == 4) &&
-		(rr->data[0] == SSL3_MT_CLIENT_REQUEST) &&
+		(rr->data[0] == SSL3_MT_HELLO_REQUEST) &&
 		(s->session != NULL) && (s->session->cipher != NULL))
 		{
 		if ((rr->data[1] != 0) || (rr->data[2] != 0) ||
 			(rr->data[3] != 0))
 			{
 			al=SSL_AD_DECODE_ERROR;
-			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_BAD_CLIENT_REQUEST);
+			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_BAD_HELLO_REQUEST);
 			goto err;
 			}
 
@@ -1038,4 +1077,3 @@ int ssl3_dispatch_alert(SSL *s)
 		}
 	return(i);
 	}
-

ssl/s3_srvr.c

@@ -503,7 +503,7 @@ static int ssl3_send_hello_request(SSL *s)
 	if (s->state == SSL3_ST_SW_HELLO_REQ_A)
 		{
 		p=(unsigned char *)s->init_buf->data;
-		*(p++)=SSL3_MT_CLIENT_REQUEST;
+		*(p++)=SSL3_MT_HELLO_REQUEST;
 		*(p++)=0;
 		*(p++)=0;
 		*(p++)=0;

ssl/ssl.h

@@ -441,7 +441,7 @@ struct ssl_ctx_st
 	/* get client cert callback */
 /**/	int (*client_cert_cb)(/* SSL *ssl, X509 **x509, EVP_PKEY **pkey */);
 
-	/* what we put in client requests */
+	/* what we put in client cert requests */
 	STACK_OF(X509_NAME) *client_CA;
 
 /**/	int quiet_shutdown;
@@ -575,7 +575,8 @@ struct ssl_st
 	struct ssl2_ctx_st *s2;	/* SSLv2 variables */
 	struct ssl3_ctx_st *s3;	/* SSLv3 variables */
 
-	int read_ahead;		/* Read as many input bytes as possible */
+	int read_ahead;		/* Read as many input bytes as possible
+	               	 	 * (for non-blocking reads) */
 	int hit;		/* reusing a previous session */
 
 	int purpose;		/* Purpose setting */
@@ -1310,7 +1311,7 @@ int SSL_COMP_add_compression_method(int id,char *cm);
 #define SSL_R_BAD_AUTHENTICATION_TYPE			 102
 #define SSL_R_BAD_CHANGE_CIPHER_SPEC			 103
 #define SSL_R_BAD_CHECKSUM				 104
-#define SSL_R_BAD_CLIENT_REQUEST			 105
+#define SSL_R_BAD_HELLO_REQUEST			 	 105
 #define SSL_R_BAD_DATA_RETURNED_BY_CALLBACK		 106
 #define SSL_R_BAD_DECOMPRESSION				 107
 #define SSL_R_BAD_DH_G_LENGTH				 108

ssl/ssl3.h

@@ -158,22 +158,6 @@ extern "C" {
 #define SSL3_RT_MAX_PACKET_SIZE		(SSL3_RT_MAX_ENCRYPTED_LENGTH+SSL3_RT_HEADER_LENGTH)
 #define SSL3_RT_MAX_DATA_SIZE			(1024*1024)
 
-/* the states that a SSL3_RECORD can be in
- * For SSL_read it goes
- * rbuf->ENCODED	-> read 
- * ENCODED		-> we need to decode everything - call decode_record
- */
- 
-#define SSL3_RS_BLANK			1
-#define SSL3_RS_DATA
-
-#define SSL3_RS_ENCODED			2
-#define SSL3_RS_READ_MORE		3
-#define SSL3_RS_WRITE_MORE
-#define SSL3_RS_PLAIN			3
-#define SSL3_RS_PART_READ		4
-#define SSL3_RS_PART_WRITE		5
-
 #define SSL3_MD_CLIENT_FINISHED_CONST	"\x43\x4C\x4E\x54"
 #define SSL3_MD_SERVER_FINISHED_CONST	"\x53\x52\x56\x52"
 
@@ -205,7 +189,6 @@ extern "C" {
 typedef struct ssl3_record_st
 	{
 /*r */	int type;		/* type of record */
-/*  */	/*int state;*/		/* any data in it? */
 /*rw*/	unsigned int length;	/* How many bytes available */
 /*r */	unsigned int off;	/* read/write offset into 'buf' */
 /*rw*/	unsigned char *data;	/* pointer to the record data */
@@ -215,11 +198,10 @@ typedef struct ssl3_record_st
 
 typedef struct ssl3_buffer_st
 	{
-/*r */	int total;		/* used in non-blocking writes */
+	unsigned char *buf;	/* SSL3_RT_MAX_PACKET_SIZE bytes (more if
-/*r */	int wanted;		/* how many more bytes we need */
+	                   	 * SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER is set) */
-/*rw*/	int left;		/* how many bytes left */
+	int offset;		/* where to 'copy from' */
-/*rw*/	int offset;		/* where to 'copy from' */
+	int left;		/* how many bytes left */
-/*rw*/	unsigned char *buf;	/* SSL3_RT_MAX_PACKET_SIZE bytes */
 	} SSL3_BUFFER;
 
 #define SSL3_CT_RSA_SIGN			1
@@ -436,7 +418,7 @@ typedef struct ssl3_ctx_st
 #define SSL3_ST_SW_FINISHED_A		(0x1E0|SSL_ST_ACCEPT)
 #define SSL3_ST_SW_FINISHED_B		(0x1E1|SSL_ST_ACCEPT)
 
-#define SSL3_MT_CLIENT_REQUEST			0
+#define SSL3_MT_HELLO_REQUEST			0
 #define SSL3_MT_CLIENT_HELLO			1
 #define SSL3_MT_SERVER_HELLO			2
 #define SSL3_MT_CERTIFICATE			11

ssl/ssl_err.c

@@ -205,7 +205,7 @@ static ERR_STRING_DATA SSL_str_reasons[]=
 {SSL_R_BAD_AUTHENTICATION_TYPE           ,"bad authentication type"},
 {SSL_R_BAD_CHANGE_CIPHER_SPEC            ,"bad change cipher spec"},
 {SSL_R_BAD_CHECKSUM                      ,"bad checksum"},
-{SSL_R_BAD_CLIENT_REQUEST                ,"bad client request"},
+{SSL_R_BAD_HELLO_REQUEST                 ,"bad hello request"},
 {SSL_R_BAD_DATA_RETURNED_BY_CALLBACK     ,"bad data returned by callback"},
 {SSL_R_BAD_DECOMPRESSION                 ,"bad decompression"},
 {SSL_R_BAD_DH_G_LENGTH                   ,"bad dh g length"},