Convert ssl_cipher_list_to_bytes() to CBB, changing the function to return

the number of bytes written via an explicit *outlen argument and retaining
the return value to indicate success or failure.

ok doug@

4 files changed, 53 insertions, 32 deletions

diff --git a/src/lib/libssl/s23_clnt.c b/src/lib/libssl/s23_clnt.c
index c6920e2b34..8674cdf627 100644
--- a/src/lib/libssl/s23_clnt.c
+++ b/src/lib/libssl/s23_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: s23_clnt.c,v 1.46 2015/09/11 18:08:21 jsing Exp $ */
+/* $OpenBSD: s23_clnt.c,v 1.47 2016/12/04 14:32:30 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -230,11 +230,11 @@ ssl23_client_hello(SSL *s)
 {
         unsigned char *buf;
         unsigned char *p, *d;
-        int i;
         unsigned long l;
         int version = 0, version_major, version_minor;
         int ret;
         unsigned long mask, options = s->options;
+        size_t outlen;
 
         /*
          * SSL_OP_NO_X disables all protocols above X *if* there are
@@ -294,14 +294,16 @@ ssl23_client_hello(SSL *s)
                 *(p++) = 0;
 
                 /* Ciphers supported (using SSL 3.0/TLS 1.0 format) */
-                i = ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s), &p[2]);
-                if (i == 0) {
-                        SSLerr(SSL_F_SSL23_CLIENT_HELLO,
+                if (!ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s), &p[2],
+                    buf - &p[2] + SSL3_RT_MAX_PLAIN_LENGTH, &outlen))
+                        return -1;
+                if (outlen == 0) {
+                        SSLerr(SSL_F_SSL3_CLIENT_HELLO,
                             SSL_R_NO_CIPHERS_AVAILABLE);
                         return -1;
                 }
-                s2n(i, p);
-                p += i;
+                s2n(outlen, p);
+                p += outlen;
 
                 /* add in (no) COMPRESSION */
                 *(p++) = 1;
diff --git a/src/lib/libssl/s3_clnt.c b/src/lib/libssl/s3_clnt.c
index 7a327a76a3..f39ae7fab3 100644
--- a/src/lib/libssl/s3_clnt.c
+++ b/src/lib/libssl/s3_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: s3_clnt.c,v 1.148 2016/12/04 14:25:44 jsing Exp $ */
+/* $OpenBSD: s3_clnt.c,v 1.149 2016/12/04 14:32:30 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -588,8 +588,11 @@ int
 ssl3_client_hello(SSL *s)
 {
         unsigned char   *bufend, *p, *d;
+        size_t           outlen;
         int              i;
 
+        bufend = (unsigned char *)s->init_buf->data + SSL3_RT_MAX_PLAIN_LENGTH;
+
         if (s->state == SSL3_ST_CW_CLNT_HELLO_A) {
                 SSL_SESSION *sess = s->session;
 
@@ -678,22 +681,22 @@ ssl3_client_hello(SSL *s)
                 }
 
                 /* Ciphers supported */
-                i = ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s), &p[2]);
-                if (i == 0) {
+                if (!ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s), &p[2],
+                    bufend - &p[2], &outlen))
+                        goto err;
+                if (outlen == 0) {
                         SSLerr(SSL_F_SSL3_CLIENT_HELLO,
                             SSL_R_NO_CIPHERS_AVAILABLE);
                         goto err;
                 }
-                s2n(i, p);
-                p += i;
+                s2n(outlen, p);
+                p += outlen;
 
                 /* add in (no) COMPRESSION */
                 *(p++) = 1;
                 *(p++) = 0; /* Add the NULL method */
 
                 /* TLS extensions*/
-                bufend = (unsigned char *)s->init_buf->data +
-                    SSL3_RT_MAX_PLAIN_LENGTH;
                 if ((p = ssl_add_clienthello_tlsext(s, p, bufend)) == NULL) {
                         SSLerr(SSL_F_SSL3_CLIENT_HELLO,
                             ERR_R_INTERNAL_ERROR);
diff --git a/src/lib/libssl/ssl_lib.c b/src/lib/libssl/ssl_lib.c
index ebe78808c5..5d93a3bc13 100644
--- a/src/lib/libssl/ssl_lib.c
+++ b/src/lib/libssl/ssl_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_lib.c,v 1.121 2016/11/02 11:21:05 jsing Exp $ */
+/* $OpenBSD: ssl_lib.c,v 1.122 2016/12/04 14:32:30 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1363,35 +1363,51 @@ SSL_get_shared_ciphers(const SSL *s, char *buf, int len)
 }
 
 int
-ssl_cipher_list_to_bytes(SSL *s, STACK_OF(SSL_CIPHER) *sk, unsigned char *p)
+ssl_cipher_list_to_bytes(SSL *s, STACK_OF(SSL_CIPHER) *sk, unsigned char *p,
+    size_t maxlen, size_t *outlen)
 {
-        int              i;
-        SSL_CIPHER      *c;
-        unsigned char   *q;
+        SSL_CIPHER *cipher;
+        int ciphers = 0;
+        CBB cbb;
+        int i;
+
+        *outlen = 0;
 
         if (sk == NULL)
                 return (0);
-        q = p;
+
+        if (!CBB_init_fixed(&cbb, p, maxlen))
+                goto err;
 
         for (i = 0; i < sk_SSL_CIPHER_num(sk); i++) {
-                c = sk_SSL_CIPHER_value(sk, i);
+                cipher = sk_SSL_CIPHER_value(sk, i);
 
                 /* Skip TLS v1.2 only ciphersuites if lower than v1.2 */
-                if ((c->algorithm_ssl & SSL_TLSV1_2) &&
+                if ((cipher->algorithm_ssl & SSL_TLSV1_2) &&
                     (TLS1_get_client_version(s) < TLS1_2_VERSION))
                         continue;
 
-                s2n(ssl3_cipher_get_value(c), p);
+                if (!CBB_add_u16(&cbb, ssl3_cipher_get_value(cipher)))
+                        goto err;
+
+                ciphers++;
         }
 
-        /*
-         * If p == q, no ciphers and caller indicates an error. Otherwise
-         * add SCSV if not renegotiating.
-         */
-        if (p != q && !s->renegotiate)
-                s2n(SSL3_CK_SCSV & SSL3_CK_VALUE_MASK, p);
+        /* Add SCSV if there are other ciphers and we're not renegotiating. */
+        if (ciphers > 0 && !s->renegotiate) {
+                if (!CBB_add_u16(&cbb, SSL3_CK_SCSV & SSL3_CK_VALUE_MASK))
+                        goto err;
+        }
+
+        if (!CBB_finish(&cbb, NULL, outlen))
+                goto err;
+
+        return 1;
+
+ err:
+        CBB_cleanup(&cbb);
 
-        return (p - q);
+        return 0;
 }
 
 STACK_OF(SSL_CIPHER) *
diff --git a/src/lib/libssl/ssl_locl.h b/src/lib/libssl/ssl_locl.h
index 6c36795b1d..c7ae289a3a 100644
--- a/src/lib/libssl/ssl_locl.h
+++ b/src/lib/libssl/ssl_locl.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_locl.h,v 1.136 2016/11/06 17:21:04 jsing Exp $ */
+/* $OpenBSD: ssl_locl.h,v 1.137 2016/12/04 14:32:30 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -569,7 +569,7 @@ int ssl_cipher_ptr_id_cmp(const SSL_CIPHER * const *ap,
 STACK_OF(SSL_CIPHER) *ssl_bytes_to_cipher_list(SSL *s, const unsigned char *p,
     int num);
 int ssl_cipher_list_to_bytes(SSL *s, STACK_OF(SSL_CIPHER) *sk,
-    unsigned char *p);
+    unsigned char *p, size_t maxlen, size_t *outlen);
 STACK_OF(SSL_CIPHER) *ssl_create_cipher_list(const SSL_METHOD *meth,
     STACK_OF(SSL_CIPHER) **pref, STACK_OF(SSL_CIPHER) **sorted,
     const char *rule_str);