Convert ssl3_send_newsession_ticket() to CBB.

This removes a memorable BUF_MEM_grow() and associated comment.

ok inoguchi@ tb@

1 files changed, 64 insertions, 55 deletions

diff --git a/src/lib/libssl/ssl_srvr.c b/src/lib/libssl/ssl_srvr.c
index 2fde588cb9..80c7208c13 100644
--- a/src/lib/libssl/ssl_srvr.c
+++ b/src/lib/libssl/ssl_srvr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_srvr.c,v 1.39 2018/08/16 18:13:15 jsing Exp $ */
+/* $OpenBSD: ssl_srvr.c,v 1.40 2018/08/19 15:29:26 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -2527,10 +2527,14 @@ ssl3_send_server_certificate(SSL *s)
 int
 ssl3_send_newsession_ticket(SSL *s)
 {
-        unsigned char *d, *p, *macstart;
+        CBB cbb, session_ticket, ticket;
+        unsigned char *enc_ticket = NULL;
         unsigned char *senc = NULL;
         const unsigned char *const_p;
-        int len, slen_full, slen;
+        unsigned char *p, *hmac;
+        size_t hmac_len;
+        int enc_ticket_len, slen;
+        int slen_full = 0;
         SSL_SESSION *sess;
         unsigned int hlen;
         EVP_CIPHER_CTX ctx;
@@ -2539,7 +2543,16 @@ ssl3_send_newsession_ticket(SSL *s)
         unsigned char iv[EVP_MAX_IV_LENGTH];
         unsigned char key_name[16];
 
+        EVP_CIPHER_CTX_init(&ctx);
+        HMAC_CTX_init(&hctx);
+
+        memset(&cbb, 0, sizeof(cbb));
+
         if (S3I(s)->hs.state == SSL3_ST_SW_SESSION_TICKET_A) {
+                if (!ssl3_handshake_msg_start_cbb(s, &cbb, &session_ticket,
+                    SSL3_MT_NEWSESSION_TICKET))
+                        goto err;
+
                 /* get session encoding length */
                 slen_full = i2d_SSL_SESSION(s->session, NULL);
                 /*
@@ -2576,24 +2589,6 @@ ssl3_send_newsession_ticket(SSL *s)
                 SSL_SESSION_free(sess);
 
                 /*
-                 * Grow buffer if need be: the length calculation is as
-                 * follows 1 (size of message name) + 3 (message length
-                 * bytes) + 4 (ticket lifetime hint) + 2 (ticket length) +
-                 * 16 (key name) + max_iv_len (iv length) +
-                 * session_length + max_enc_block_size (max encrypted session
-                 * length) + max_md_size (HMAC).
-                 */
-                if (!BUF_MEM_grow(s->internal->init_buf, ssl3_handshake_msg_hdr_len(s) +
-                    22 + EVP_MAX_IV_LENGTH + EVP_MAX_BLOCK_LENGTH +
-                    EVP_MAX_MD_SIZE + slen))
-                        goto err;
-
-                d = p = ssl3_handshake_msg_start(s, SSL3_MT_NEWSESSION_TICKET);
-
-                EVP_CIPHER_CTX_init(&ctx);
-                HMAC_CTX_init(&hctx);
-
-                /*
                  * Initialize HMAC and cipher contexts. If callback present
                  * it does all the work otherwise use generated values
                  * from parent ctx.
@@ -2613,55 +2608,69 @@ ssl3_send_newsession_ticket(SSL *s)
                         memcpy(key_name, tctx->internal->tlsext_tick_key_name, 16);
                 }
 
+                /* Encrypt the session ticket. */
+                if ((enc_ticket = calloc(1, slen + EVP_MAX_BLOCK_LENGTH)) == NULL)
+                        goto err;
+                if (!EVP_EncryptUpdate(&ctx, enc_ticket, &enc_ticket_len, senc, slen))
+                        goto err;
+                if (!EVP_EncryptFinal_ex(&ctx, enc_ticket, &enc_ticket_len))
+                        goto err;
+
+                /* Generate the HMAC. */
+                if (!HMAC_Update(&hctx, key_name, sizeof(key_name)))
+                        goto err;
+                if (!HMAC_Update(&hctx, iv, EVP_CIPHER_CTX_iv_length(&ctx)))
+                        goto err;
+                if (!HMAC_Update(&hctx, enc_ticket, enc_ticket_len))
+                        goto err;
+
+                if ((hmac_len = HMAC_size(&hctx)) <= 0)
+                        goto err;
+
                 /*
                  * Ticket lifetime hint (advisory only):
                  * We leave this unspecified for resumed session
                  * (for simplicity), and guess that tickets for new
                  * sessions will live as long as their sessions.
                  */
-                l2n(s->internal->hit ? 0 : s->session->timeout, p);
-
-                /* Skip ticket length for now */
-                p += 2;
-                /* Output key name */
-                macstart = p;
-                memcpy(p, key_name, 16);
-                p += 16;
-                /* output IV */
-                memcpy(p, iv, EVP_CIPHER_CTX_iv_length(&ctx));
-                p += EVP_CIPHER_CTX_iv_length(&ctx);
-                /* Encrypt session data */
-                EVP_EncryptUpdate(&ctx, p, &len, senc, slen);
-                p += len;
-                EVP_EncryptFinal_ex(&ctx, p, &len);
-                p += len;
-                EVP_CIPHER_CTX_cleanup(&ctx);
-
-                HMAC_Update(&hctx, macstart, p - macstart);
-                HMAC_Final(&hctx, p, &hlen);
-                HMAC_CTX_cleanup(&hctx);
-                p += hlen;
-
-                /* Now write out lengths: p points to end of data written */
-                /* Total length */
-                len = p - d;
-
-                /* Skip ticket lifetime hint. */
-                p = d + 4;
-                s2n(len - 6, p); /* Message length */
-
-                ssl3_handshake_msg_finish(s, len);
+                if (!CBB_add_u32(&session_ticket,
+                    s->internal->hit ? 0 : s->session->timeout))
+                        goto err;
 
-                S3I(s)->hs.state = SSL3_ST_SW_SESSION_TICKET_B;
+                if (!CBB_add_u16_length_prefixed(&session_ticket, &ticket))
+                        goto err;
+                if (!CBB_add_bytes(&ticket, key_name, sizeof(key_name)))
+                        goto err;
+                if (!CBB_add_bytes(&ticket, iv, EVP_CIPHER_CTX_iv_length(&ctx)))
+                        goto err;
+                if (!CBB_add_bytes(&ticket, enc_ticket, enc_ticket_len))
+                        goto err;
+                if (!CBB_add_space(&ticket, &hmac, hmac_len))
+                        goto err;
 
-                freezero(senc, slen_full);
+                if (!HMAC_Final(&hctx, hmac, &hlen))
+                        goto err;
+
+                if (!ssl3_handshake_msg_finish_cbb(s, &cbb))
+                        goto err;
+
+                S3I(s)->hs.state = SSL3_ST_SW_SESSION_TICKET_B;
         }
 
+        EVP_CIPHER_CTX_cleanup(&ctx);
+        HMAC_CTX_cleanup(&hctx);
+        freezero(senc, slen_full);
+        free(enc_ticket);
+
         /* SSL3_ST_SW_SESSION_TICKET_B */
         return (ssl3_handshake_write(s));
 
  err:
+        CBB_cleanup(&cbb);
+        EVP_CIPHER_CTX_cleanup(&ctx);
+        HMAC_CTX_cleanup(&hctx);
         freezero(senc, slen_full);
+        free(enc_ticket);
 
         return (-1);
 }