Rewrite the ECPointFormats TLS extension handling using CBB/CBS and the

new extension framework.

input + ok jsing@

4 files changed, 125 insertions, 147 deletions

diff --git a/src/lib/libssl/ssl_locl.h b/src/lib/libssl/ssl_locl.h
index 8ef2d01402..c11c5899e3 100644
--- a/src/lib/libssl/ssl_locl.h
+++ b/src/lib/libssl/ssl_locl.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_locl.h,v 1.184 2017/08/10 17:18:38 jsing Exp $ */
+/* $OpenBSD: ssl_locl.h,v 1.185 2017/08/11 05:06:34 doug Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1380,6 +1380,9 @@ int SSL_state_func_code(int _state);
 #define SSLerrorx(r) ERR_PUT_error(ERR_LIB_SSL,(0xfff),(r),__FILE__,__LINE__)
 void SSL_error_internal(const SSL *s, int r, char *f, int l);
 
+void tls1_get_formatlist(SSL *s, int client_formats, const uint8_t **pformats,
+    size_t *pformatslen);
+
 __END_HIDDEN_DECLS
 
 #endif
diff --git a/src/lib/libssl/ssl_tlsext.c b/src/lib/libssl/ssl_tlsext.c
index 400c69fa87..e8723b502c 100644
--- a/src/lib/libssl/ssl_tlsext.c
+++ b/src/lib/libssl/ssl_tlsext.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.c,v 1.3 2017/07/24 17:39:43 jsing Exp $ */
+/* $OpenBSD: ssl_tlsext.c,v 1.4 2017/08/11 05:06:34 doug Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  *
@@ -21,6 +21,103 @@
 #include "ssl_tlsext.h"
 
 /*
+ * Supported Point Formats Extension - RFC 4492 section 5.1.2
+ */
+static int
+tlsext_ecpf_build(SSL *s, CBB *cbb)
+{
+        CBB ecpf;
+        size_t formats_len;
+        const uint8_t *formats;
+
+        tls1_get_formatlist(s, 0, &formats, &formats_len);
+
+        if (formats_len == 0) {
+                SSLerror(s, ERR_R_INTERNAL_ERROR);
+                return 0;
+        }
+
+        if (!CBB_add_u8_length_prefixed(cbb, &ecpf))
+                return 0;
+        if (!CBB_add_bytes(&ecpf, formats, formats_len))
+                return 0;
+        if (!CBB_flush(cbb))
+                return 0;
+
+        return 1;
+}
+
+static int
+tlsext_ecpf_parse(SSL *s, CBS *cbs, int *alert)
+{
+        CBS ecpf;
+
+        if (!CBS_get_u8_length_prefixed(cbs, &ecpf))
+                goto err;
+        if (CBS_len(&ecpf) == 0)
+                goto err;
+        if (CBS_len(cbs) != 0)
+                goto err;
+
+        /* Must contain uncompressed (0) */
+        if (!CBS_contains_zero_byte(&ecpf)) {
+                SSLerror(s, SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
+                goto err;
+        }
+
+        if (!s->internal->hit) {
+                if (!CBS_stow(&ecpf, &(SSI(s)->tlsext_ecpointformatlist),
+                    &(SSI(s)->tlsext_ecpointformatlist_length)))
+                        goto err;
+        }
+
+        return 1;
+
+ err:
+        *alert = TLS1_AD_INTERNAL_ERROR;
+        return 0;
+}
+
+int
+tlsext_ecpf_clienthello_needs(SSL *s)
+{
+        return ssl_has_ecc_ciphers(s);
+}
+
+int
+tlsext_ecpf_clienthello_build(SSL *s, CBB *cbb)
+{
+        return tlsext_ecpf_build(s, cbb);
+}
+
+int
+tlsext_ecpf_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+        return tlsext_ecpf_parse(s, cbs, alert);
+}
+
+int
+tlsext_ecpf_serverhello_needs(SSL *s)
+{
+        if (s->version == DTLS1_VERSION)
+                return 0;
+
+        return ssl_using_ecc_cipher(s);
+}
+
+int
+tlsext_ecpf_serverhello_build(SSL *s, CBB *cbb)
+{
+        return tlsext_ecpf_build(s, cbb);
+}
+
+int
+tlsext_ecpf_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+        return tlsext_ecpf_parse(s, cbs, alert);
+}
+
+/*
  * Renegotiation Indication - RFC 5746.
  */
 int
@@ -313,6 +410,15 @@ static struct tls_extension tls_extensions[] = {
                 .serverhello_build = tlsext_ri_serverhello_build,
                 .serverhello_parse = tlsext_ri_serverhello_parse,
         },
+        {
+                .type = TLSEXT_TYPE_ec_point_formats,
+                .clienthello_needs = tlsext_ecpf_clienthello_needs,
+                .clienthello_build = tlsext_ecpf_clienthello_build,
+                .clienthello_parse = tlsext_ecpf_clienthello_parse,
+                .serverhello_needs = tlsext_ecpf_serverhello_needs,
+                .serverhello_build = tlsext_ecpf_serverhello_build,
+                .serverhello_parse = tlsext_ecpf_serverhello_parse,
+        },
 };
 
 #define N_TLS_EXTENSIONS (sizeof(tls_extensions) / sizeof(*tls_extensions))
diff --git a/src/lib/libssl/ssl_tlsext.h b/src/lib/libssl/ssl_tlsext.h
index 4b0194861a..67a9cfb688 100644
--- a/src/lib/libssl/ssl_tlsext.h
+++ b/src/lib/libssl/ssl_tlsext.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.h,v 1.2 2017/07/24 17:10:31 jsing Exp $ */
+/* $OpenBSD: ssl_tlsext.h,v 1.3 2017/08/11 05:06:34 doug Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  *
@@ -29,6 +29,13 @@ int tlsext_sni_serverhello_needs(SSL *s);
 int tlsext_sni_serverhello_build(SSL *s, CBB *cbb);
 int tlsext_sni_serverhello_parse(SSL *s, CBS *cbs, int *alert);
 
+int tlsext_ecpf_clienthello_needs(SSL *s);
+int tlsext_ecpf_clienthello_build(SSL *s, CBB *cbb);
+int tlsext_ecpf_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tlsext_ecpf_serverhello_needs(SSL *s);
+int tlsext_ecpf_serverhello_build(SSL *s, CBB *cbb);
+int tlsext_ecpf_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
 int tlsext_clienthello_build(SSL *s, CBB *cbb);
 int tlsext_clienthello_parse_one(SSL *s, CBS *cbs, uint16_t tlsext_type,
     int *alert);
diff --git a/src/lib/libssl/t1_lib.c b/src/lib/libssl/t1_lib.c
index 42fd18fe2d..2e90d3e9df 100644
--- a/src/lib/libssl/t1_lib.c
+++ b/src/lib/libssl/t1_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: t1_lib.c,v 1.124 2017/08/10 17:18:38 jsing Exp $ */
+/* $OpenBSD: t1_lib.c,v 1.125 2017/08/11 05:06:34 doug Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -342,7 +342,7 @@ tls1_ec_nid2curve_id(int nid)
  * the client/session formats. Otherwise return the custom format list if one
  * exists, or the default formats if a custom list has not been specified.
  */
-static void
+void
 tls1_get_formatlist(SSL *s, int client_formats, const uint8_t **pformats,
     size_t *pformatslen)
 {
@@ -699,34 +699,11 @@ ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned char *limit)
         ret += len;
 
         if (using_ecc) {
-                size_t curveslen, formatslen, lenmax;
+                size_t curveslen, lenmax;
                 const uint16_t *curves;
-                const uint8_t *formats;
                 int i;
 
                 /*
-                 * Add TLS extension ECPointFormats to the ClientHello message.
-                 */
-                tls1_get_formatlist(s, 0, &formats, &formatslen);
-
-                if ((size_t)(limit - ret) < 5)
-                        return NULL;
-
-                lenmax = limit - ret - 5;
-                if (formatslen > lenmax)
-                        return NULL;
-                if (formatslen > 255) {
-                        SSLerror(s, ERR_R_INTERNAL_ERROR);
-                        return NULL;
-                }
-
-                s2n(TLSEXT_TYPE_ec_point_formats, ret);
-                s2n(formatslen + 1, ret);
-                *(ret++) = (unsigned char)formatslen;
-                memcpy(ret, formats, formatslen);
-                ret += formatslen;
-
-                /*
                  * Add TLS extension EllipticCurves to the ClientHello message.
                  */
                 tls1_get_curvelist(s, 0, &curves, &curveslen);
@@ -931,14 +908,12 @@ skip_ext:
 unsigned char *
 ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned char *limit)
 {
-        int using_ecc, extdatalen = 0;
+        int extdatalen = 0;
         unsigned char *ret = p;
         int next_proto_neg_seen;
         size_t len;
         CBB cbb;
 
-        using_ecc = ssl_using_ecc_cipher(s);
-
         ret += 2;
         if (ret >= limit)
                 return NULL; /* this really never occurs, but ... */
@@ -957,33 +932,6 @@ ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned char *limit)
                 return NULL;
         ret += len;
 
-        if (using_ecc && s->version != DTLS1_VERSION) {
-                const unsigned char *formats;
-                size_t formatslen, lenmax;
-
-                /*
-                 * Add TLS extension ECPointFormats to the ServerHello message.
-                 */
-                tls1_get_formatlist(s, 0, &formats, &formatslen);
-
-                if ((size_t)(limit - ret) < 5)
-                        return NULL;
-
-                lenmax = limit - ret - 5;
-                if (formatslen > lenmax)
-                        return NULL;
-                if (formatslen > 255) {
-                        SSLerror(s, ERR_R_INTERNAL_ERROR);
-                        return NULL;
-                }
-
-                s2n(TLSEXT_TYPE_ec_point_formats, ret);
-                s2n(formatslen + 1, ret);
-                *(ret++) = (unsigned char)formatslen;
-                memcpy(ret, formats, formatslen);
-                ret += formatslen;
-        }
-
         /*
          * Currently the server should not respond with a SupportedCurves
          * extension.
@@ -1194,38 +1142,7 @@ ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
                 if (!tlsext_clienthello_parse_one(s, &cbs, type, al))
                         return 0;
 
-                if (type == TLSEXT_TYPE_ec_point_formats &&
-                    s->version != DTLS1_VERSION) {
-                        unsigned char *sdata = data;
-                        size_t formatslen;
-                        uint8_t *formats;
-
-                        if (size < 1) {
-                                *al = TLS1_AD_DECODE_ERROR;
-                                return 0;
-                        }
-                        formatslen = *(sdata++);
-                        if (formatslen != size - 1) {
-                                *al = TLS1_AD_DECODE_ERROR;
-                                return 0;
-                        }
-
-                        if (!s->internal->hit) {
-                                free(SSI(s)->tlsext_ecpointformatlist);
-                                SSI(s)->tlsext_ecpointformatlist = NULL;
-                                SSI(s)->tlsext_ecpointformatlist_length = 0;
-
-                                if ((formats = reallocarray(NULL, formatslen,
-                                    sizeof(uint8_t))) == NULL) {
-                                        *al = TLS1_AD_INTERNAL_ERROR;
-                                        return 0;
-                                }
-                                memcpy(formats, sdata, formatslen);
-                                SSI(s)->tlsext_ecpointformatlist = formats;
-                                SSI(s)->tlsext_ecpointformatlist_length =
-                                    formatslen;
-                        }
-                } else if (type == TLSEXT_TYPE_elliptic_curves &&
+                if (type == TLSEXT_TYPE_elliptic_curves &&
                     s->version != DTLS1_VERSION) {
                         unsigned char *sdata = data;
                         size_t curveslen, i;
@@ -1510,39 +1427,7 @@ ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, size_t n, int *al)
                 if (!tlsext_serverhello_parse_one(s, &cbs, type, al))
                         return 0;
 
-                if (type == TLSEXT_TYPE_ec_point_formats &&
-                    s->version != DTLS1_VERSION) {
-                        unsigned char *sdata = data;
-                        size_t formatslen;
-                        uint8_t *formats;
-
-                        if (size < 1) {
-                                *al = TLS1_AD_DECODE_ERROR;
-                                return 0;
-                        }
-                        formatslen = *(sdata++);
-                        if (formatslen != size - 1) {
-                                *al = TLS1_AD_DECODE_ERROR;
-                                return 0;
-                        }
-
-                        if (!s->internal->hit) {
-                                free(SSI(s)->tlsext_ecpointformatlist);
-                                SSI(s)->tlsext_ecpointformatlist = NULL;
-                                SSI(s)->tlsext_ecpointformatlist_length = 0;
-
-                                if ((formats = reallocarray(NULL, formatslen,
-                                    sizeof(uint8_t))) == NULL) {
-                                        *al = TLS1_AD_INTERNAL_ERROR;
-                                        return 0;
-                                }
-                                memcpy(formats, sdata, formatslen);
-                                SSI(s)->tlsext_ecpointformatlist = formats;
-                                SSI(s)->tlsext_ecpointformatlist_length =
-                                    formatslen;
-                        }
-                }
-                else if (type == TLSEXT_TYPE_session_ticket) {
+                if (type == TLSEXT_TYPE_session_ticket) {
                         if (s->internal->tls_session_ticket_ext_cb &&
                             !s->internal->tls_session_ticket_ext_cb(s, data, size, s->internal->tls_session_ticket_ext_cb_arg)) {
                                 *al = TLS1_AD_INTERNAL_ERROR;
@@ -1779,29 +1664,6 @@ ssl_check_serverhello_tlsext(SSL *s)
         int ret = SSL_TLSEXT_ERR_NOACK;
         int al = SSL_AD_UNRECOGNIZED_NAME;
 
-        /* If we are client and using an elliptic curve cryptography cipher
-         * suite, then if server returns an EC point formats lists extension
-         * it must contain uncompressed.
-         */
-        if (ssl_using_ecc_cipher(s) &&
-            s->internal->tlsext_ecpointformatlist != NULL &&
-            s->internal->tlsext_ecpointformatlist_length > 0) {
-                /* we are using an ECC cipher */
-                size_t i;
-                unsigned char *list;
-                int found_uncompressed = 0;
-                list = SSI(s)->tlsext_ecpointformatlist;
-                for (i = 0; i < SSI(s)->tlsext_ecpointformatlist_length; i++) {
-                        if (*(list++) == TLSEXT_ECPOINTFORMAT_uncompressed) {
-                                found_uncompressed = 1;
-                                break;
-                        }
-                }
-                if (!found_uncompressed) {
-                        SSLerror(s, SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
-                        return -1;
-                }
-        }
         ret = SSL_TLSEXT_ERR_OK;
 
         if (s->ctx != NULL && s->ctx->internal->tlsext_servername_callback != 0)