Fix for "Record of death" vulnerability CVE-2010-0740.
[openssl.git] / ssl / s3_pkt.c
index 1d34cec324e19e89aa2b23fc21307e4dfefdafbb..b30c032b74e01c316f145a3ccab4975dde34e7c4 100644 (file)
 #include "ssl_locl.h"
 #include <openssl/evp.h>
 #include <openssl/buffer.h>
+#include <openssl/rand.h>
 
 static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
                         unsigned int len, int create_empty_fragment);
@@ -129,16 +130,21 @@ int ssl3_read_n(SSL *s, int n, int max, int extend)
         * (If s->read_ahead is set, 'max' bytes may be stored in rbuf
         * [plus s->packet_length bytes if extend == 1].)
         */
-       int i,len,left,align=0;
+       int i,len,left;
+       long align=0;
        unsigned char *pkt;
        SSL3_BUFFER *rb;
 
        if (n <= 0) return n;
 
        rb    = &(s->s3->rbuf);
+       if (rb->buf == NULL)
+               if (!ssl3_setup_read_buffer(s))
+                       return -1;
+
        left  = rb->left;
 #if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
-       align = (int)rb->buf + SSL3_RT_HEADER_LENGTH;
+       align = (long)rb->buf + SSL3_RT_HEADER_LENGTH;
        align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
 #endif
 
@@ -155,7 +161,7 @@ int ssl3_read_n(SSL *s, int n, int max, int extend)
                        if (pkt[0] == SSL3_RT_APPLICATION_DATA
                            && (pkt[3]<<8|pkt[4]) >= 128)
                                {
-                               /* Note that even if packet is corrupted
+                               /* Note that even if packet is corrupted
                                 * and its length field is insane, we can
                                 * only be led to wrong decision about
                                 * whether memmove will occur or not.
@@ -171,11 +177,12 @@ int ssl3_read_n(SSL *s, int n, int max, int extend)
                /* ... now we can act as if 'extend' was set */
                }
 
-       /* extend reads should not span multiple packets for DTLS */
-       if ( SSL_version(s) == DTLS1_VERSION &&
-               extend)
+       /* For DTLS/UDP reads should not span multiple packets
+        * because the read operation returns the whole packet
+        * at once (as long as it fits into the buffer). */
+       if (SSL_version(s) == DTLS1_VERSION || SSL_version(s) == DTLS1_BAD_VER)
                {
-               if ( left > 0 && n > left)
+               if (left > 0 && n > left)
                        n = left;
                }
 
@@ -202,15 +209,22 @@ int ssl3_read_n(SSL *s, int n, int max, int extend)
                rb->offset = len + align;
                }
 
-       max = rb->len - rb->offset;
-       if (n > max) /* does not happen */
+       if (n > (int)(rb->len - rb->offset)) /* does not happen */
                {
                SSLerr(SSL_F_SSL3_READ_N,ERR_R_INTERNAL_ERROR);
                return -1;
                }
 
        if (!s->read_ahead)
-               max=n;
+               /* ignore max parameter */
+               max = n;
+       else
+               {
+               if (max < n)
+                       max = n;
+               if (max > (int)(rb->len - rb->offset))
+                       max = rb->len - rb->offset;
+               }
 
        while (left < n)
                {
@@ -233,9 +247,20 @@ int ssl3_read_n(SSL *s, int n, int max, int extend)
                if (i <= 0)
                        {
                        rb->left = left;
+                       if (s->mode & SSL_MODE_RELEASE_BUFFERS)
+                               if (len+left == 0)
+                                       ssl3_release_read_buffer(s);
                        return(i);
                        }
                left+=i;
+               /* reads should *never* span multiple packets for DTLS because
+                * the underlying transport protocol is message oriented as opposed
+                * to byte oriented as in the TLS case. */
+               if (SSL_version(s) == DTLS1_VERSION || SSL_version(s) == DTLS1_BAD_VER)
+                       {
+                       if (n > left)
+                               n = left; /* makes the while condition false */
+                       }
                }
 
        /* done reading, now the book-keeping */
@@ -264,7 +289,7 @@ static int ssl3_get_record(SSL *s)
        unsigned char *p;
        unsigned char md[EVP_MAX_MD_SIZE];
        short version;
-       unsigned int mac_size;
+       int mac_size;
        int clear=0;
        size_t extra;
        int decryption_failed_or_bad_record_mac = 0;
@@ -307,18 +332,14 @@ fprintf(stderr, "Record type=%d, Length=%d\n", rr->type, rr->length);
 #endif
 
                /* Lets check version */
-               if (s->first_packet)
-                       {
-                       s->first_packet=0;
-                       }
-               else
+               if (!s->first_packet)
                        {
                        if (version != s->version)
                                {
                                SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_WRONG_VERSION_NUMBER);
-                               /* Send back error using their
-                                * version number :-) */
-                               s->version=version;
+                                if ((s->version & 0xFF00) == (version & 0xFF00))
+                                       /* Send back error using their minor version number :-) */
+                                       s->version = (unsigned short)version;
                                al=SSL_AD_PROTOCOL_VERSION;
                                goto f_err;
                                }
@@ -403,12 +424,14 @@ printf("\n");
        /* r->length is now the compressed data plus mac */
        if (    (sess == NULL) ||
                (s->enc_read_ctx == NULL) ||
-               (s->read_hash == NULL))
+               (EVP_MD_CTX_md(s->read_hash) == NULL))
                clear=1;
 
        if (!clear)
                {
-               mac_size=EVP_MD_size(s->read_hash);
+               /* !clear => s->read_hash != NULL => mac_size != -1 */
+               mac_size=EVP_MD_CTX_size(s->read_hash);
+               OPENSSL_assert(mac_size >= 0);
 
                if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH+extra+mac_size)
                        {
@@ -421,7 +444,7 @@ printf("\n");
 #endif                 
                        }
                /* check the MAC for rr->input (it's in mac_size bytes at the tail) */
-               if (rr->length >= mac_size)
+               if (rr->length >= (unsigned int)mac_size)
                        {
                        rr->length -= mac_size;
                        mac = &rr->data[rr->length];
@@ -439,7 +462,7 @@ printf("\n");
 #endif
                        }
                i=s->method->ssl3_enc->mac(s,md,0);
-               if (mac == NULL || memcmp(md, mac, mac_size) != 0)
+               if (i < 0 || mac == NULL || memcmp(md, mac, (size_t)mac_size) != 0)
                        {
                        decryption_failed_or_bad_record_mac = 1;
                        }
@@ -606,11 +629,17 @@ static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
        {
        unsigned char *p,*plen;
        int i,mac_size,clear=0;
-       int prefix_len=0,align=0;
+       int prefix_len=0;
+       int eivlen;
+       long align=0;
        SSL3_RECORD *wr;
        SSL3_BUFFER *wb=&(s->s3->wbuf);
        SSL_SESSION *sess;
 
+       if (wb->buf == NULL)
+               if (!ssl3_setup_write_buffer(s))
+                       return -1;
+
        /* first check if there is a SSL3_BUFFER still being written
         * out.  This will happen with non blocking IO */
        if (wb->left != 0)
@@ -633,13 +662,17 @@ static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
 
        if (    (sess == NULL) ||
                (s->enc_write_ctx == NULL) ||
-               (s->write_hash == NULL))
+               (EVP_MD_CTX_md(s->write_hash) == NULL))
                clear=1;
 
        if (clear)
                mac_size=0;
        else
-               mac_size=EVP_MD_size(s->write_hash);
+               {
+               mac_size=EVP_MD_CTX_size(s->write_hash);
+               if (mac_size < 0)
+                       goto err;
+               }
 
        /* 'create_empty_fragment' is true only when this function calls itself */
        if (!clear && !create_empty_fragment && !s->s3->empty_fragment_done)
@@ -676,7 +709,7 @@ static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
                 * which would be multiple of SSL3_ALIGN_PAYLOAD, so
                 * if we want to align the real payload, then we can
                 * just pretent we simply have two headers. */
-               align = (int)wb->buf + 2*SSL3_RT_HEADER_LENGTH;
+               align = (long)wb->buf + 2*SSL3_RT_HEADER_LENGTH;
                align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
 #endif
                p = wb->buf + align;
@@ -689,7 +722,7 @@ static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
        else
                {
 #if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
-               align = (int)wb->buf + SSL3_RT_HEADER_LENGTH;
+               align = (long)wb->buf + SSL3_RT_HEADER_LENGTH;
                align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
 #endif
                p = wb->buf + align;
@@ -707,9 +740,18 @@ static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
        /* field where we are to write out packet length */
        plen=p; 
        p+=2;
+       /* Explicit IV length, block ciphers and TLS version 1.1 or later */
+       if (s->enc_write_ctx && s->version >= TLS1_1_VERSION)
+               {
+               eivlen = EVP_CIPHER_CTX_iv_length(s->enc_write_ctx);
+               if (eivlen <= 1)
+                       eivlen = 0;
+               }
+       else 
+               eivlen = 0;
 
        /* lets setup the record stuff. */
-       wr->data=p;
+       wr->data=p + eivlen;
        wr->length=(int)len;
        wr->input=(unsigned char *)buf;
 
@@ -737,10 +779,19 @@ static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
 
        if (mac_size != 0)
                {
-               s->method->ssl3_enc->mac(s,&(p[wr->length]),1);
+               if (s->method->ssl3_enc->mac(s,&(p[wr->length + eivlen]),1) < 0)
+                       goto err;
                wr->length+=mac_size;
-               wr->input=p;
-               wr->data=p;
+               }
+
+       wr->input=p;
+       wr->data=p;
+
+       if (eivlen)
+               {
+       /*      if (RAND_pseudo_bytes(p, eivlen) <= 0)
+                       goto err; */
+               wr->length += eivlen;
                }
 
        /* ssl3_enc can only have an error on read */
@@ -814,11 +865,20 @@ int ssl3_write_pending(SSL *s, int type, const unsigned char *buf,
                        {
                        wb->left=0;
                        wb->offset+=i;
+                       if (s->mode & SSL_MODE_RELEASE_BUFFERS)
+                               ssl3_release_write_buffer(s);
                        s->rwstate=SSL_NOTHING;
                        return(s->s3->wpend_ret);
                        }
-               else if (i <= 0)
+               else if (i <= 0) {
+                       if (s->version == DTLS1_VERSION ||
+                           s->version == DTLS1_BAD_VER) {
+                               /* For DTLS, just drop it. That's kind of the whole
+                                  point in using a datagram service */
+                               wb->left = 0;
+                       }
                        return(i);
+               }
                wb->offset+=i;
                wb->left-=i;
                }
@@ -859,7 +919,7 @@ int ssl3_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek)
        void (*cb)(const SSL *ssl,int type2,int val)=NULL;
 
        if (s->s3->rbuf.buf == NULL) /* Not initialized yet */
-               if (!ssl3_setup_buffers(s))
+               if (!ssl3_setup_read_buffer(s))
                        return(-1);
 
        if ((type && (type != SSL3_RT_APPLICATION_DATA) && (type != SSL3_RT_HANDSHAKE) && type) ||
@@ -968,6 +1028,8 @@ start:
                                {
                                s->rstate=SSL_ST_READ_HEADER;
                                rr->off=0;
+                               if (s->mode & SSL_MODE_RELEASE_BUFFERS)
+                                       ssl3_release_read_buffer(s);
                                }
                        }
                return(n);
@@ -1077,7 +1139,25 @@ start:
                 * now try again to obtain the (application) data we were asked for */
                goto start;
                }
-
+       /* If we are a server and get a client hello when renegotiation isn't
+        * allowed send back a no renegotiation alert and carry on.
+        * WARNING: experimental code, needs reviewing (steve)
+        */
+       if (s->server &&
+               SSL_is_init_finished(s) &&
+               !s->s3->send_connection_binding &&
+               (s->version > SSL3_VERSION) &&
+               (s->s3->handshake_fragment_len >= 4) &&
+               (s->s3->handshake_fragment[0] == SSL3_MT_CLIENT_HELLO) &&
+               (s->session != NULL) && (s->session->cipher != NULL) &&
+               !(s->ctx->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
+               
+               {
+               /*s->s3->handshake_fragment_len = 0;*/
+               rr->length = 0;
+               ssl3_send_alert(s,SSL3_AL_WARNING, SSL_AD_NO_RENEGOTIATION);
+               goto start;
+               }
        if (s->s3->alert_fragment_len >= 2)
                {
                int alert_level = s->s3->alert_fragment[0];
@@ -1107,6 +1187,21 @@ start:
                                s->shutdown |= SSL_RECEIVED_SHUTDOWN;
                                return(0);
                                }
+                       /* This is a warning but we receive it if we requested
+                        * renegotiation and the peer denied it. Terminate with
+                        * a fatal alert because if application tried to
+                        * renegotiatie it presumably had a good reason and
+                        * expects it to succeed.
+                        *
+                        * In future we might have a renegotiation where we
+                        * don't care if the peer refused it where we carry on.
+                        */
+                       else if (alert_descr == SSL_AD_NO_RENEGOTIATION)
+                               {
+                               al = SSL_AD_HANDSHAKE_FAILURE;
+                               SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_NO_RENEGOTIATION);
+                               goto f_err;
+                               }
                        }
                else if (alert_level == 2) /* fatal */
                        {
@@ -1219,7 +1314,7 @@ start:
        default:
 #ifndef OPENSSL_NO_TLS
                /* TLS just ignores unknown message types */
-               if (s->version == TLS1_VERSION)
+               if (s->version >= TLS1_VERSION && s->version <= TLS1_1_VERSION)
                        {
                        rr->length = 0;
                        goto start;
@@ -1289,6 +1384,13 @@ int ssl3_do_change_cipher_spec(SSL *s)
 
        if (s->s3->tmp.key_block == NULL)
                {
+               if (s->session == NULL) 
+                       {
+                       /* might happen if dtls1_read_bytes() calls this */
+                       SSLerr(SSL_F_SSL3_DO_CHANGE_CIPHER_SPEC,SSL_R_CCS_RECEIVED_EARLY);
+                       return (0);
+                       }
+
                s->session->cipher=s->s3->tmp.new_cipher;
                if (!s->method->ssl3_enc->setup_key_block(s)) return(0);
                }
@@ -1311,20 +1413,18 @@ int ssl3_do_change_cipher_spec(SSL *s)
                }
 
        s->s3->tmp.peer_finish_md_len = s->method->ssl3_enc->final_finish_mac(s,
-               &(s->s3->finish_dgst1),
-               &(s->s3->finish_dgst2),
                sender,slen,s->s3->tmp.peer_finish_md);
 
        return(1);
        }
 
-void ssl3_send_alert(SSL *s, int level, int desc)
+int ssl3_send_alert(SSL *s, int level, int desc)
        {
        /* Map tls/ssl alert value to correct one */
        desc=s->method->ssl3_enc->alert_value(desc);
        if (s->version == SSL3_VERSION && desc == SSL_AD_PROTOCOL_VERSION)
                desc = SSL_AD_HANDSHAKE_FAILURE; /* SSL 3.0 does not have protocol_version alerts */
-       if (desc < 0) return;
+       if (desc < 0) return -1;
        /* If a fatal one, remove from cache */
        if ((level == 2) && (s->session != NULL))
                SSL_CTX_remove_session(s->ctx,s->session);
@@ -1333,9 +1433,10 @@ void ssl3_send_alert(SSL *s, int level, int desc)
        s->s3->send_alert[0]=level;
        s->s3->send_alert[1]=desc;
        if (s->s3->wbuf.left == 0) /* data still being written out? */
-               s->method->ssl_dispatch_alert(s);
+               return s->method->ssl_dispatch_alert(s);
        /* else data is still being written out, we will get written
         * some time in the future */
+       return -1;
        }
 
 int ssl3_dispatch_alert(SSL *s)