Implement a new custom extensions API
authorMatt Caswell <matt@openssl.org>
Wed, 5 Apr 2017 10:59:23 +0000 (11:59 +0100)
committerMatt Caswell <matt@openssl.org>
Fri, 7 Apr 2017 12:41:04 +0000 (13:41 +0100)
The old custom extensions API was not TLSv1.3 aware. Extensions are used
extensively in TLSv1.3 and they can appear in many different types of
messages. Therefore we need a new API to be able to cope with that.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3139)

include/openssl/ssl.h
ssl/ssl_cert.c
ssl/ssl_locl.h
ssl/ssl_rsa.c
ssl/statem/extensions.c
ssl/statem/extensions_clnt.c
ssl/statem/extensions_cust.c
ssl/statem/statem_locl.h
util/libssl.num

index 8e2d934fdea21d306da5994c3bcc3581d72da03b..8dbfe91f633e684641e8bbf3948af0452d504575 100644 (file)
@@ -259,19 +259,21 @@ typedef int (*tls_session_secret_cb_fn) (SSL *s, void *secret,
 #define SSL_EXT_TLS_IMPLEMENTATION_ONLY         0x0004
 /* Most extensions are not defined for SSLv3 but EXT_TYPE_renegotiate is */
 #define SSL_EXT_SSL3_ALLOWED                    0x0008
-/* Extension is only defined for TLS1.2 and above */
+/* Extension is only defined for TLS1.2 and below */
 #define SSL_EXT_TLS1_2_AND_BELOW_ONLY           0x0010
 /* Extension is only defined for TLS1.3 and above */
 #define SSL_EXT_TLS1_3_ONLY                     0x0020
-#define SSL_EXT_CLIENT_HELLO                    0x0040
+/* Ignore this extension during parsing if we are resuming */
+#define SSL_EXT_IGNORE_ON_RESUMPTION            0x0040
+#define SSL_EXT_CLIENT_HELLO                    0x0080
 /* Really means TLS1.2 or below */
-#define SSL_EXT_TLS1_2_SERVER_HELLO             0x0080
-#define SSL_EXT_TLS1_3_SERVER_HELLO             0x0100
-#define SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS     0x0200
-#define SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST      0x0400
-#define SSL_EXT_TLS1_3_CERTIFICATE              0x0800
-#define SSL_EXT_TLS1_3_NEW_SESSION_TICKET       0x1000
-#define SSL_EXT_TLS1_3_CERTIFICATE_REQUEST      0x2000
+#define SSL_EXT_TLS1_2_SERVER_HELLO             0x0100
+#define SSL_EXT_TLS1_3_SERVER_HELLO             0x0200
+#define SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS     0x0400
+#define SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST      0x0800
+#define SSL_EXT_TLS1_3_CERTIFICATE              0x1000
+#define SSL_EXT_TLS1_3_NEW_SESSION_TICKET       0x2000
+#define SSL_EXT_TLS1_3_CERTIFICATE_REQUEST      0x4000
 
 /* Typedefs for handling custom extensions */
 
@@ -286,6 +288,23 @@ typedef int (*custom_ext_parse_cb) (SSL *s, unsigned int ext_type,
                                     const unsigned char *in,
                                     size_t inlen, int *al, void *parse_arg);
 
+
+typedef int (*custom_ext_add_cb_ex) (SSL *s, unsigned int ext_type,
+                                     unsigned int context,
+                                     const unsigned char **out,
+                                     size_t *outlen, X509 *x, size_t chainidx,
+                                     int *al, void *add_arg);
+
+typedef void (*custom_ext_free_cb_ex) (SSL *s, unsigned int ext_type,
+                                       unsigned int context,
+                                       const unsigned char *out, void *add_arg);
+
+typedef int (*custom_ext_parse_cb_ex) (SSL *s, unsigned int ext_type,
+                                       unsigned int context,
+                                       const unsigned char *in,
+                                       size_t inlen, X509 *x, size_t chainidx,
+                                       int *al, void *parse_arg);
+
 /* Typedef for verification callback */
 typedef int (*SSL_verify_cb)(int preverify_ok, X509_STORE_CTX *x509_ctx);
 
@@ -779,6 +798,14 @@ __owur int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
                                   custom_ext_parse_cb parse_cb,
                                   void *parse_arg);
 
+__owur int SSL_CTX_add_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
+                                  unsigned int context,
+                                  custom_ext_add_cb_ex add_cb,
+                                  custom_ext_free_cb_ex free_cb,
+                                  void *add_arg,
+                                  custom_ext_parse_cb_ex parse_cb,
+                                  void *parse_arg);
+
 __owur int SSL_extension_supported(unsigned int ext_type);
 
 # define SSL_NOTHING            1
index a4e7977012e5dbe8fb53c86af7e63c19b5aa3827..3a85ede6384c52fee74587ab2489f19fa4e9a91e 100644 (file)
@@ -190,9 +190,7 @@ CERT *ssl_cert_dup(CERT *cert)
     ret->sec_level = cert->sec_level;
     ret->sec_ex = cert->sec_ex;
 
-    if (!custom_exts_copy(&ret->cli_ext, &cert->cli_ext))
-        goto err;
-    if (!custom_exts_copy(&ret->srv_ext, &cert->srv_ext))
+    if (!custom_exts_copy(&ret->custext, &cert->custext))
         goto err;
 #ifndef OPENSSL_NO_PSK
     if (cert->psk_identity_hint) {
@@ -254,8 +252,7 @@ void ssl_cert_free(CERT *c)
     OPENSSL_free(c->ctype);
     X509_STORE_free(c->verify_store);
     X509_STORE_free(c->chain_store);
-    custom_exts_free(&c->cli_ext);
-    custom_exts_free(&c->srv_ext);
+    custom_exts_free(&c->custext);
 #ifndef OPENSSL_NO_PSK
     OPENSSL_free(c->psk_identity_hint);
 #endif
index f53293109b4613a0da8e273249a859f096e093d1..a9ac840e105b0b4d8350baf66c8099ca19dccaca 100644 (file)
@@ -1618,15 +1618,22 @@ struct cert_pkey_st {
 
 typedef struct {
     unsigned short ext_type;
+    /*
+     * Set to 1 if this is only for the server side, 0 if it is only for the
+     * client side, or -1 if it is either.
+     */
+    int server;
+    /* The context which this extension applies to */
+    unsigned int context;
     /*
      * Per-connection flags relating to this extension type: not used if
      * part of an SSL_CTX structure.
      */
     uint32_t ext_flags;
-    custom_ext_add_cb add_cb;
-    custom_ext_free_cb free_cb;
+    custom_ext_add_cb_ex add_cb;
+    custom_ext_free_cb_ex free_cb;
     void *add_arg;
-    custom_ext_parse_cb parse_cb;
+    custom_ext_parse_cb_ex parse_cb;
     void *parse_arg;
 } custom_ext_method;
 
@@ -1706,9 +1713,8 @@ typedef struct cert_st {
      */
     X509_STORE *chain_store;
     X509_STORE *verify_store;
-    /* Custom extension methods for server and client */
-    custom_ext_methods cli_ext;
-    custom_ext_methods srv_ext;
+    /* Custom extensions */
+    custom_ext_methods custext;
     /* Security callback */
     int (*sec_cb) (const SSL *s, const SSL_CTX *ctx, int op, int bits, int nid,
                    void *other, void *ex);
@@ -2436,15 +2442,18 @@ __owur int srp_generate_server_master_secret(SSL *s);
 __owur int srp_generate_client_master_secret(SSL *s);
 __owur int srp_verify_server_param(SSL *s, int *al);
 
-/* t1_ext.c */
+/* statem/extensions_cust.c */
+
+custom_ext_method *custom_ext_find(const custom_ext_methods *exts, int server,
+                                   unsigned int ext_type, size_t *idx);
 
 void custom_ext_init(custom_ext_methods *meths);
 
-__owur int custom_ext_parse(SSL *s, int server,
-                            unsigned int ext_type,
+__owur int custom_ext_parse(SSL *s, unsigned int context, unsigned int ext_type,
                             const unsigned char *ext_data, size_t ext_size,
-                            int *al);
-__owur int custom_ext_add(SSL *s, int server, WPACKET *pkt, int *al);
+                            X509 *x, size_t chainidx, int *al);
+__owur int custom_ext_add(SSL *s, int context, WPACKET *pkt, X509 *x,
+                          size_t chainidx, int maxversion, int *al);
 
 __owur int custom_exts_copy(custom_ext_methods *dst,
                             const custom_ext_methods *src);
index a94fb13b89b54c8592753b4e0791271fd7a6bb5b..ecf2ff3e73c32ddfc728ac0d9599f89b111434b2 100644 (file)
@@ -797,26 +797,15 @@ static int serverinfo_process_buffer(const unsigned char *serverinfo,
 
         /* Register callbacks for extensions */
         ext_type = (serverinfo[0] << 8) + serverinfo[1];
-        if (ctx) {
-            int have_ext_cbs = 0;
-            size_t i;
-            custom_ext_methods *exts = &ctx->cert->srv_ext;
-            custom_ext_method *meth = exts->meths;
-
-            for (i = 0; i < exts->meths_count; i++, meth++) {
-                if (ext_type == meth->ext_type) {
-                    have_ext_cbs = 1;
-                    break;
-                }
-            }
-
-            if (!have_ext_cbs && !SSL_CTX_add_server_custom_ext(ctx, ext_type,
-                                                                serverinfo_srv_add_cb,
-                                                                NULL, NULL,
-                                                                serverinfo_srv_parse_cb,
-                                                                NULL))
-                return 0;
-        }
+        if (ctx != NULL
+                && custom_ext_find(&ctx->cert->custext, 1, ext_type, NULL)
+                   == NULL
+                && !SSL_CTX_add_server_custom_ext(ctx, ext_type,
+                                                  serverinfo_srv_add_cb,
+                                                  NULL, NULL,
+                                                  serverinfo_srv_parse_cb,
+                                                  NULL))
+            return 0;
 
         serverinfo += 2;
         serverinfo_length -= 2;
index c2e0411240669704d38864e9b5a116976dbc14e8..49a7156a2cfc3458a6ff1e1334e351daa458504d 100644 (file)
@@ -329,6 +329,23 @@ static const EXTENSION_DEFINITION ext_defs[] = {
     }
 };
 
+/* Check whether an extension's context matches the current context */
+static int validate_context(SSL *s, unsigned int extctx, unsigned int thisctx)
+{
+    /* Check we're allowed to use this extension in this context */
+    if ((thisctx & extctx) == 0)
+        return 0;
+
+    if (SSL_IS_DTLS(s)) {
+        if ((extctx & SSL_EXT_TLS_ONLY) != 0)
+            return 0;
+    } else if ((extctx & SSL_EXT_DTLS_ONLY) != 0) {
+        return 0;
+    }
+
+    return 1;
+}
+
 /*
  * Verify whether we are allowed to use the extension |type| in the current
  * |context|. Returns 1 to indicate the extension is allowed or unknown or 0 to
@@ -345,38 +362,31 @@ static int verify_extension(SSL *s, unsigned int context, unsigned int type,
 
     for (i = 0, thisext = ext_defs; i < builtin_num; i++, thisext++) {
         if (type == thisext->type) {
-            /* Check we're allowed to use this extension in this context */
-            if ((context & thisext->context) == 0)
+            if (!validate_context(s, thisext->context, context))
                 return 0;
 
-            if (SSL_IS_DTLS(s)) {
-                if ((thisext->context & SSL_EXT_TLS_ONLY) != 0)
-                    return 0;
-            } else if ((thisext->context & SSL_EXT_DTLS_ONLY) != 0) {
-                    return 0;
-            }
-
             *found = &rawexlist[i];
             return 1;
         }
     }
 
-    if ((context & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO)) == 0) {
-        /*
-         * Custom extensions only apply to <=TLS1.2. This extension is unknown
-         * in this context - we allow it
-         */
-        *found = NULL;
-        return 1;
-    }
-
     /* Check the custom extensions */
     if (meths != NULL) {
-        for (i = builtin_num; i < builtin_num + meths->meths_count; i++) {
-            if (meths->meths[i - builtin_num].ext_type == type) {
-                *found = &rawexlist[i];
-                return 1;
-            }
+        size_t offset = 0;
+        int server = -1;
+        custom_ext_method *meth = NULL;
+
+        if ((context & SSL_EXT_CLIENT_HELLO) != 0)
+            server = 1;
+        else if ((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0)
+            server = 0;
+
+        meth = custom_ext_find(meths, server, type, &offset);
+        if (meth != NULL) {
+            if (!validate_context(s, meth->context, context))
+                return 0;
+            *found = &rawexlist[offset + builtin_num];
+            return 1;
         }
     }
 
@@ -390,8 +400,7 @@ static int verify_extension(SSL *s, unsigned int context, unsigned int type,
  * the extension is relevant for the current context |thisctx| or not. Returns
  * 1 if the extension is relevant for this context, and 0 otherwise
  */
-static int extension_is_relevant(SSL *s, unsigned int extctx,
-                                 unsigned int thisctx)
+int extension_is_relevant(SSL *s, unsigned int extctx, unsigned int thisctx)
 {
     if ((SSL_IS_DTLS(s)
                 && (extctx & SSL_EXT_TLS_IMPLEMENTATION_ONLY) != 0)
@@ -399,7 +408,8 @@ static int extension_is_relevant(SSL *s, unsigned int extctx,
                     && (extctx & SSL_EXT_SSL3_ALLOWED) == 0)
             || (SSL_IS_TLS13(s)
                 && (extctx & SSL_EXT_TLS1_2_AND_BELOW_ONLY) != 0)
-            || (!SSL_IS_TLS13(s) && (extctx & SSL_EXT_TLS1_3_ONLY) != 0))
+            || (!SSL_IS_TLS13(s) && (extctx & SSL_EXT_TLS1_3_ONLY) != 0)
+            || (s->hit && (extctx & SSL_EXT_IGNORE_ON_RESUMPTION) != 0))
         return 0;
 
     return 1;
@@ -427,7 +437,7 @@ int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
     PACKET extensions = *packet;
     size_t i = 0;
     size_t num_exts;
-    custom_ext_methods *exts = NULL;
+    custom_ext_methods *exts = &s->cert->custext;
     RAW_EXTENSION *raw_extensions = NULL;
     const EXTENSION_DEFINITION *thisexd;
 
@@ -437,12 +447,8 @@ int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
      * Initialise server side custom extensions. Client side is done during
      * construction of extensions for the ClientHello.
      */
-    if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
-        exts = &s->cert->srv_ext;
-        custom_ext_init(&s->cert->srv_ext);
-    } else if ((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0) {
-        exts = &s->cert->cli_ext;
-    }
+    if ((context & SSL_EXT_CLIENT_HELLO) != 0)
+        custom_ext_init(&s->cert->custext);
 
     num_exts = OSSL_NELEM(ext_defs) + (exts != NULL ? exts->meths_count : 0);
     raw_extensions = OPENSSL_zalloc(num_exts * sizeof(*raw_extensions));
@@ -560,21 +566,11 @@ int tls_parse_extension(SSL *s, TLSEXT_INDEX idx, int context,
          */
     }
 
-    /*
-     * This is a custom extension. We only allow this if it is a non
-     * resumed session on the server side.
-     *chain
-     * TODO(TLS1.3): We only allow old style <=TLS1.2 custom extensions.
-     * We're going to need a new mechanism for TLS1.3 to specify which
-     * messages to add the custom extensions to.
-     */
-    if ((!s->hit || !s->server)
-            && (context
-                & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO)) != 0
-            && custom_ext_parse(s, s->server, currext->type,
-                                PACKET_data(&currext->data),
-                                PACKET_remaining(&currext->data),
-                                al) <= 0)
+    /* Parse custom extensions */
+    if (custom_ext_parse(s, context, currext->type,
+                         PACKET_data(&currext->data),
+                         PACKET_remaining(&currext->data),
+                         x, chainidx, al) <= 0)
         return 0;
 
     return 1;
@@ -595,11 +591,7 @@ int tls_parse_all_extensions(SSL *s, int context, RAW_EXTENSION *exts, X509 *x,
     const EXTENSION_DEFINITION *thisexd;
 
     /* Calculate the number of extensions in the extensions list */
-    if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
-        numexts += s->cert->srv_ext.meths_count;
-    } else if ((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0) {
-        numexts += s->cert->cli_ext.meths_count;
-    }
+    numexts += s->cert->custext.meths_count;
 
     /* Parse each extension in turn */
     for (i = 0; i < numexts; i++) {
@@ -621,6 +613,30 @@ int tls_parse_all_extensions(SSL *s, int context, RAW_EXTENSION *exts, X509 *x,
     return 1;
 }
 
+int should_add_extension(SSL *s, unsigned int extctx, unsigned int thisctx,
+                         int max_version)
+{
+    /* Skip if not relevant for our context */
+    if ((extctx & thisctx) == 0)
+        return 0;
+
+    /* Check if this extension is defined for our protocol. If not, skip */
+    if ((SSL_IS_DTLS(s) && (extctx & SSL_EXT_TLS_IMPLEMENTATION_ONLY) != 0)
+            || (s->version == SSL3_VERSION
+                    && (extctx & SSL_EXT_SSL3_ALLOWED) == 0)
+            || (SSL_IS_TLS13(s)
+                && (extctx & SSL_EXT_TLS1_2_AND_BELOW_ONLY) != 0)
+            || (!SSL_IS_TLS13(s)
+                && (extctx & SSL_EXT_TLS1_3_ONLY) != 0
+                && (thisctx & SSL_EXT_CLIENT_HELLO) == 0)
+            || ((extctx & SSL_EXT_TLS1_3_ONLY) != 0
+                && (thisctx & SSL_EXT_CLIENT_HELLO) != 0
+                && (SSL_IS_DTLS(s) || max_version < TLS1_3_VERSION)))
+        return 0;
+
+    return 1;
+}
+
 /*
  * Construct all the extensions relevant to the current |context| and write
  * them to |pkt|. If this is an extension for a Certificate in a Certificate
@@ -634,7 +650,7 @@ int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
                              X509 *x, size_t chainidx, int *al)
 {
     size_t i;
-    int addcustom = 0, min_version, max_version = 0, reason, tmpal;
+    int min_version, max_version = 0, reason, tmpal;
     const EXTENSION_DEFINITION *thisexd;
 
     /*
@@ -667,21 +683,10 @@ int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
 
     /* Add custom extensions first */
     if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
-        custom_ext_init(&s->cert->cli_ext);
-        addcustom = 1;
-    } else if ((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0) {
-        /*
-         * We already initialised the custom extensions during ClientHello
-         * parsing.
-         *
-         * TODO(TLS1.3): We're going to need a new custom extension mechanism
-         * for TLS1.3, so that custom extensions can specify which of the
-         * multiple message they wish to add themselves to.
-         */
-        addcustom = 1;
+        /* On the server side with initiase during ClientHello parsing */
+        custom_ext_init(&s->cert->custext);
     }
-
-    if (addcustom && !custom_ext_add(s, s->server, pkt, &tmpal)) {
+    if (!custom_ext_add(s, context, pkt, x, chainidx, max_version, &tmpal)) {
         SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);
         goto err;
     }
@@ -691,28 +696,13 @@ int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
                          size_t chainidx, int *al);
 
         /* Skip if not relevant for our context */
-        if ((thisexd->context & context) == 0)
+        if (!should_add_extension(s, thisexd->context, context, max_version))
             continue;
 
         construct = s->server ? thisexd->construct_stoc
                               : thisexd->construct_ctos;
 
-        /* Check if this extension is defined for our protocol. If not, skip */
-        if ((SSL_IS_DTLS(s)
-                    && (thisexd->context & SSL_EXT_TLS_IMPLEMENTATION_ONLY)
-                       != 0)
-                || (s->version == SSL3_VERSION
-                        && (thisexd->context & SSL_EXT_SSL3_ALLOWED) == 0)
-                || (SSL_IS_TLS13(s)
-                    && (thisexd->context & SSL_EXT_TLS1_2_AND_BELOW_ONLY)
-                       != 0)
-                || (!SSL_IS_TLS13(s)
-                    && (thisexd->context & SSL_EXT_TLS1_3_ONLY) != 0
-                    && (context & SSL_EXT_CLIENT_HELLO) == 0)
-                || ((thisexd->context & SSL_EXT_TLS1_3_ONLY) != 0
-                    && (context & SSL_EXT_CLIENT_HELLO) != 0
-                    && (SSL_IS_DTLS(s) || max_version < TLS1_3_VERSION))
-                || construct == NULL)
+        if (construct == NULL)
             continue;
 
         if (!construct(s, pkt, context, x, chainidx, &tmpal))
index af894945076e0ab6d52d288219d92a3f611debee..7d2a4b04a5f135c32492502836e9d5ccbefe19a5 100644 (file)
@@ -1092,8 +1092,10 @@ int tls_parse_stoc_sct(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
             }
         }
     } else {
-        if (custom_ext_parse(s, 0, TLSEXT_TYPE_signed_certificate_timestamp,
-                             PACKET_data(pkt), PACKET_remaining(pkt), al) <= 0)
+        if (custom_ext_parse(s, context,
+                             TLSEXT_TYPE_signed_certificate_timestamp,
+                             PACKET_data(pkt), PACKET_remaining(pkt),
+                             x, chainidx, al) <= 0)
             return 0;
     }
 
index 374fe1e55e6b89689fb588db4daf154fd3373945..ec1ab6d539080e97554d4d9ee3f304674b236df6 100644 (file)
@@ -9,18 +9,86 @@
 
 /* Custom extension utility functions */
 
+#include <assert.h>
 #include <openssl/ct.h>
 #include "../ssl_locl.h"
+#include "statem_locl.h"
 
-/* Find a custom extension from the list. */
-static custom_ext_method *custom_ext_find(const custom_ext_methods *exts,
-                                          unsigned int ext_type)
+typedef struct {
+    void *add_arg;
+    custom_ext_add_cb add_cb;
+    custom_ext_free_cb free_cb;
+} custom_ext_add_cb_wrap;
+
+typedef struct {
+    void *parse_arg;
+    custom_ext_parse_cb parse_cb;
+} custom_ext_parse_cb_wrap;
+
+/*
+ * Provide thin wrapper callbacks which convert new style arguments to old style
+ */
+static int custom_ext_add_old_cb_wrap(SSL *s, unsigned int ext_type,
+                                      unsigned int context,
+                                      const unsigned char **out,
+                                      size_t *outlen, X509 *x, size_t chainidx,
+                                      int *al, void *add_arg)
+{
+    custom_ext_add_cb_wrap *add_cb_wrap = (custom_ext_add_cb_wrap *)add_arg;
+
+    if (add_cb_wrap->add_cb == NULL)
+        return 1;
+
+    return add_cb_wrap->add_cb(s, ext_type, out, outlen, al,
+                               add_cb_wrap->add_arg);
+}
+
+static void custom_ext_free_old_cb_wrap(SSL *s, unsigned int ext_type,
+                                        unsigned int context,
+                                        const unsigned char *out, void *add_arg)
+{
+    custom_ext_add_cb_wrap *add_cb_wrap = (custom_ext_add_cb_wrap *)add_arg;
+
+    if (add_cb_wrap->free_cb == NULL)
+        return;
+
+    add_cb_wrap->free_cb(s, ext_type, out, add_cb_wrap->add_arg);
+}
+
+static int custom_ext_parse_old_cb_wrap(SSL *s, unsigned int ext_type,
+                                        unsigned int context,
+                                        const unsigned char *in,
+                                        size_t inlen, X509 *x, size_t chainidx,
+                                        int *al, void *parse_arg)
+{
+    custom_ext_parse_cb_wrap *parse_cb_wrap =
+        (custom_ext_parse_cb_wrap *)parse_arg;
+
+    return parse_cb_wrap->parse_cb(s, ext_type, in, inlen, al,
+                                   parse_cb_wrap->parse_arg);
+}
+
+/*
+ * Find a custom extension from the list. The |server| param is there to
+ * support the legacy API where custom extensions for client and server could
+ * be set independently on the same SSL_CTX. It is set to 1 if we are trying
+ * to find a method relevant to the server, 0 for the client, or -1 if we don't
+ * care
+ */
+custom_ext_method *custom_ext_find(const custom_ext_methods *exts, int server,
+                                   unsigned int ext_type, size_t *idx)
 {
     size_t i;
+
     custom_ext_method *meth = exts->meths;
     for (i = 0; i < exts->meths_count; i++, meth++) {
-        if (ext_type == meth->ext_type)
+        if (ext_type == meth->ext_type
+                && (server == -1 || server == meth->server
+                    || meth->server == -1)) {
+            if (idx != NULL)
+                *idx = i;
             return meth;
+        }
     }
     return NULL;
 }
@@ -37,46 +105,63 @@ void custom_ext_init(custom_ext_methods *exts)
 }
 
 /* Pass received custom extension data to the application for parsing. */
-int custom_ext_parse(SSL *s, int server,
-                     unsigned int ext_type,
-                     const unsigned char *ext_data, size_t ext_size, int *al)
+int custom_ext_parse(SSL *s, unsigned int context, unsigned int ext_type,
+                     const unsigned char *ext_data, size_t ext_size, X509 *x,
+                     size_t chainidx, int *al)
 {
-    custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
+    custom_ext_methods *exts = &s->cert->custext;
     custom_ext_method *meth;
-    meth = custom_ext_find(exts, ext_type);
+    int server = -1;
+
+    if ((context & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO)) != 0)
+        server = s->server;
+
+    meth = custom_ext_find(exts, server, ext_type, NULL);
     /* If not found return success */
     if (!meth)
         return 1;
-    if (!server) {
+
+    /* Check if extension is defined for our protocol. If not, skip */
+    if (!extension_is_relevant(s, meth->context, context))
+        return 1;
+
+    if ((context & (SSL_EXT_TLS1_2_SERVER_HELLO
+                    | SSL_EXT_TLS1_3_SERVER_HELLO
+                    | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS)) != 0) {
         /*
-         * If it's ServerHello we can't have any extensions not sent in
-         * ClientHello.
+         * If it's ServerHello or EncryptedExtensions we can't have any
+         * extensions not sent in ClientHello.
          */
-        if (!(meth->ext_flags & SSL_EXT_FLAG_SENT)) {
+        if ((meth->ext_flags & SSL_EXT_FLAG_SENT) == 0) {
             *al = TLS1_AD_UNSUPPORTED_EXTENSION;
             return 0;
         }
     }
-    /* If already present it's a duplicate */
-    if (meth->ext_flags & SSL_EXT_FLAG_RECEIVED) {
-        *al = TLS1_AD_DECODE_ERROR;
-        return 0;
-    }
-    meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
+
+    /*
+     * Extensions received in the ClientHello are marked with the
+     * SSL_EXT_FLAG_RECEIVED. This is so we know to add the equivalent
+     * extensions in the ServerHello/EncryptedExtensions message
+     */
+    if ((context & SSL_EXT_CLIENT_HELLO) != 0)
+        meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
+
     /* If no parse function set return success */
     if (!meth->parse_cb)
         return 1;
 
-    return meth->parse_cb(s, ext_type, ext_data, ext_size, al, meth->parse_arg);
+    return meth->parse_cb(s, ext_type, context, ext_data, ext_size, x, chainidx,
+                          al, meth->parse_arg);
 }
 
 /*
  * Request custom extension data from the application and add to the return
  * buffer.
  */
-int custom_ext_add(SSL *s, int server, WPACKET *pkt, int *al)
+int custom_ext_add(SSL *s, int context, WPACKET *pkt, X509 *x, size_t chainidx,
+                   int maxversion, int *al)
 {
-    custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
+    custom_ext_methods *exts = &s->cert->custext;
     custom_ext_method *meth;
     size_t i;
 
@@ -86,20 +171,30 @@ int custom_ext_add(SSL *s, int server, WPACKET *pkt, int *al)
 
         meth = exts->meths + i;
 
-        if (server) {
+        if (!should_add_extension(s, meth->context, context, maxversion))
+            continue;
+
+        if ((context & (SSL_EXT_TLS1_2_SERVER_HELLO
+                        | SSL_EXT_TLS1_3_SERVER_HELLO
+                        | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS)) != 0) {
             /*
-             * For ServerHello only send extensions present in ClientHello.
+             * For ServerHello/EncryptedExtensions only send extensions present
+             * in ClientHello.
              */
             if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
                 continue;
-            /* If callback absent for server skip it */
-            if (!meth->add_cb)
-                continue;
         }
-        if (meth->add_cb) {
+        /*
+         * We skip it if the callback is absent - except for a ClientHello where
+         * we add an empty extension.
+         */
+        if ((context & SSL_EXT_CLIENT_HELLO) == 0 && meth->add_cb == NULL)
+            continue;
+
+        if (meth->add_cb != NULL) {
             int cb_retval = 0;
-            cb_retval = meth->add_cb(s, meth->ext_type,
-                                     &out, &outlen, al, meth->add_arg);
+            cb_retval = meth->add_cb(s, meth->ext_type, context, &out, &outlen,
+                                     x, chainidx, al, meth->add_arg);
             if (cb_retval < 0)
                 return 0;       /* error */
             if (cb_retval == 0)
@@ -113,18 +208,20 @@ int custom_ext_add(SSL *s, int server, WPACKET *pkt, int *al)
             *al = SSL_AD_INTERNAL_ERROR;
             return 0;
         }
-        /*
-         * We can't send duplicates: code logic should prevent this.
-         */
-        OPENSSL_assert(!(meth->ext_flags & SSL_EXT_FLAG_SENT));
-        /*
-         * Indicate extension has been sent: this is both a sanity check to
-         * ensure we don't send duplicate extensions and indicates that it is
-         * not an error if the extension is present in ServerHello.
-         */
-        meth->ext_flags |= SSL_EXT_FLAG_SENT;
+        if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
+            /*
+             * We can't send duplicates: code logic should prevent this.
+             */
+            assert(!(meth->ext_flags & SSL_EXT_FLAG_SENT));
+            /*
+             * Indicate extension has been sent: this is both a sanity check to
+             * ensure we don't send duplicate extensions and indicates that it
+             * is not an error if the extension is present in ServerHello.
+             */
+            meth->ext_flags |= SSL_EXT_FLAG_SENT;
+        }
         if (meth->free_cb)
-            meth->free_cb(s, meth->ext_type, out, meth->add_arg);
+            meth->free_cb(s, meth->ext_type, context, out, meth->add_arg);
     }
     return 1;
 }
@@ -132,49 +229,120 @@ int custom_ext_add(SSL *s, int server, WPACKET *pkt, int *al)
 /* Copy table of custom extensions */
 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
 {
-    if (src->meths_count) {
+    size_t i;
+    int err = 0;
+
+    if (src->meths_count > 0) {
         dst->meths =
             OPENSSL_memdup(src->meths,
                            sizeof(custom_ext_method) * src->meths_count);
         if (dst->meths == NULL)
             return 0;
         dst->meths_count = src->meths_count;
+
+        for (i = 0; i < src->meths_count; i++) {
+            custom_ext_method *methsrc = src->meths + i;
+            custom_ext_method *methdst = dst->meths + i;
+
+            if (methsrc->add_cb != custom_ext_add_old_cb_wrap)
+                continue;
+
+            /*
+             * We have found an old style API wrapper. We need to copy the
+             * arguments too.
+             */
+
+            if (err) {
+                methdst->add_arg = NULL;
+                methdst->parse_arg = NULL;
+                continue;
+            }
+
+            methdst->add_arg = OPENSSL_memdup(methsrc->add_arg,
+                                              sizeof(custom_ext_add_cb_wrap));
+            methdst->parse_arg = OPENSSL_memdup(methsrc->parse_arg,
+                                            sizeof(custom_ext_parse_cb_wrap));
+
+            if (methdst->add_arg == NULL || methdst->parse_arg == NULL)
+                err = 1;
+        }
+    }
+
+    if (err) {
+        custom_exts_free(dst);
+        return 0;
     }
+
     return 1;
 }
 
 void custom_exts_free(custom_ext_methods *exts)
 {
+    size_t i;
+
+    for (i = 0; i < exts->meths_count; i++) {
+        custom_ext_method *meth = exts->meths + i;
+
+        if (meth->add_cb != custom_ext_add_old_cb_wrap)
+            continue;
+
+        /* Old style API wrapper. Need to free the arguments too */
+        OPENSSL_free(meth->add_arg);
+        OPENSSL_free(meth->parse_arg);
+    }
     OPENSSL_free(exts->meths);
 }
 
-/* Set callbacks for a custom extension. */
-static int custom_ext_meth_add(custom_ext_methods *exts,
-                               unsigned int ext_type,
-                               custom_ext_add_cb add_cb,
-                               custom_ext_free_cb free_cb,
-                               void *add_arg,
-                               custom_ext_parse_cb parse_cb, void *parse_arg)
+/* Return true if a client custom extension exists, false otherwise */
+int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
 {
+    return custom_ext_find(&ctx->cert->custext, 0, ext_type, NULL) != NULL;
+}
+
+static int add_custom_ext_intern(SSL_CTX *ctx, int server,
+                                 unsigned int ext_type,
+                                 unsigned int context,
+                                 custom_ext_add_cb_ex add_cb,
+                                 custom_ext_free_cb_ex free_cb,
+                                 void *add_arg,
+                                 custom_ext_parse_cb_ex parse_cb,
+                                 void *parse_arg)
+{
+    custom_ext_methods *exts = &ctx->cert->custext;
     custom_ext_method *meth, *tmp;
+
     /*
      * Check application error: if add_cb is not set free_cb will never be
      * called.
      */
     if (!add_cb && free_cb)
         return 0;
+
+#ifndef OPENSSL_NO_CT
+    /*
+     * We don't want applications registering callbacks for SCT extensions
+     * whilst simultaneously using the built-in SCT validation features, as
+     * these two things may not play well together.
+     */
+    if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp
+            && (context & SSL_EXT_CLIENT_HELLO) != 0
+            && SSL_CTX_ct_is_enabled(ctx))
+        return 0;
+#endif
+
     /*
      * Don't add if extension supported internally, but make exception
      * for extension types that previously were not supported, but now are.
      */
-    if (SSL_extension_supported(ext_type) &&
-        ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
+    if (SSL_extension_supported(ext_type)
+            && ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
         return 0;
+
     /* Extension type must fit in 16 bits */
     if (ext_type > 0xffff)
         return 0;
     /* Search for duplicate */
-    if (custom_ext_find(exts, ext_type))
+    if (custom_ext_find(exts, server, ext_type, NULL))
         return 0;
     tmp = OPENSSL_realloc(exts->meths,
                           (exts->meths_count + 1) * sizeof(custom_ext_method));
@@ -185,6 +353,8 @@ static int custom_ext_meth_add(custom_ext_methods *exts,
     exts->meths = tmp;
     meth = exts->meths + exts->meths_count;
     memset(meth, 0, sizeof(*meth));
+    meth->server = server;
+    meth->context = context;
     meth->parse_cb = parse_cb;
     meth->add_cb = add_cb;
     meth->free_cb = free_cb;
@@ -195,31 +365,65 @@ static int custom_ext_meth_add(custom_ext_methods *exts,
     return 1;
 }
 
-/* Return true if a client custom extension exists, false otherwise */
-int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
+static int add_old_custom_ext(SSL_CTX *ctx, int server, unsigned int ext_type,
+                              unsigned int context,
+                              custom_ext_add_cb add_cb,
+                              custom_ext_free_cb free_cb,
+                              void *add_arg,
+                              custom_ext_parse_cb parse_cb, void *parse_arg)
 {
-    return custom_ext_find(&ctx->cert->cli_ext, ext_type) != NULL;
+    custom_ext_add_cb_wrap *add_cb_wrap
+        = OPENSSL_malloc(sizeof(custom_ext_add_cb_wrap));
+    custom_ext_parse_cb_wrap *parse_cb_wrap
+        = OPENSSL_malloc(sizeof(custom_ext_parse_cb_wrap));
+    int ret;
+
+    if (add_cb_wrap == NULL || parse_cb_wrap == NULL) {
+        OPENSSL_free(add_cb_wrap);
+        OPENSSL_free(parse_cb_wrap);
+        return 0;
+    }
+
+    add_cb_wrap->add_arg = add_arg;
+    add_cb_wrap->add_cb = add_cb;
+    add_cb_wrap->free_cb = free_cb;
+    parse_cb_wrap->parse_arg = parse_arg;
+    parse_cb_wrap->parse_cb = parse_cb;
+
+    /*
+     * TODO(TLS1.3): Is it possible with the old API to add custom exts for both
+     * client and server for the same type in the same SSL_CTX? We don't handle
+     * that yet.
+     */
+    ret = add_custom_ext_intern(ctx, server, ext_type,
+                                context,
+                                custom_ext_add_old_cb_wrap,
+                                custom_ext_free_old_cb_wrap,
+                                add_cb_wrap,
+                                custom_ext_parse_old_cb_wrap,
+                                parse_cb_wrap);
+
+    if (!ret) {
+        OPENSSL_free(add_cb_wrap);
+        OPENSSL_free(parse_cb_wrap);
+    }
+
+    return ret;
 }
 
-/* Application level functions to add custom extension callbacks */
+/* Application level functions to add the old custom extension callbacks */
 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
                                   custom_ext_add_cb add_cb,
                                   custom_ext_free_cb free_cb,
                                   void *add_arg,
                                   custom_ext_parse_cb parse_cb, void *parse_arg)
 {
-#ifndef OPENSSL_NO_CT
-    /*
-     * We don't want applications registering callbacks for SCT extensions
-     * whilst simultaneously using the built-in SCT validation features, as
-     * these two things may not play well together.
-     */
-    if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp &&
-        SSL_CTX_ct_is_enabled(ctx))
-        return 0;
-#endif
-    return custom_ext_meth_add(&ctx->cert->cli_ext, ext_type, add_cb,
-                               free_cb, add_arg, parse_cb, parse_arg);
+    return add_old_custom_ext(ctx, 0, ext_type,
+                              SSL_EXT_TLS1_2_AND_BELOW_ONLY
+                              | SSL_EXT_CLIENT_HELLO
+                              | SSL_EXT_TLS1_2_SERVER_HELLO
+                              | SSL_EXT_IGNORE_ON_RESUMPTION,
+                              add_cb, free_cb, add_arg, parse_cb, parse_arg);
 }
 
 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
@@ -228,8 +432,23 @@ int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
                                   void *add_arg,
                                   custom_ext_parse_cb parse_cb, void *parse_arg)
 {
-    return custom_ext_meth_add(&ctx->cert->srv_ext, ext_type,
-                               add_cb, free_cb, add_arg, parse_cb, parse_arg);
+    return add_old_custom_ext(ctx, 1, ext_type,
+                              SSL_EXT_TLS1_2_AND_BELOW_ONLY
+                              | SSL_EXT_CLIENT_HELLO
+                              | SSL_EXT_TLS1_2_SERVER_HELLO
+                              | SSL_EXT_IGNORE_ON_RESUMPTION,
+                              add_cb, free_cb, add_arg, parse_cb, parse_arg);
+}
+
+int SSL_CTX_add_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
+                           unsigned int context,
+                           custom_ext_add_cb_ex add_cb,
+                           custom_ext_free_cb_ex free_cb,
+                           void *add_arg,
+                           custom_ext_parse_cb_ex parse_cb, void *parse_arg)
+{
+    return add_custom_ext_intern(ctx, -1, ext_type, context, add_cb, free_cb,
+                                 add_arg, parse_cb, parse_arg);
 }
 
 int SSL_extension_supported(unsigned int ext_type)
index 43d79b8b949f0d26dc475926b66760c4a071504f..2352c6a11ea76585eade8364cb2ef8cd0ebe166e 100644 (file)
@@ -153,6 +153,8 @@ MSG_PROCESS_RETURN tls_process_end_of_early_data(SSL *s, PACKET *pkt);
 
 /* Extension processing */
 
+__owur int extension_is_relevant(SSL *s, unsigned int extctx,
+                                 unsigned int thisctx);
 __owur int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
                                   RAW_EXTENSION **res, int *al, size_t *len);
 __owur int tls_parse_extension(SSL *s, TLSEXT_INDEX idx, int context,
@@ -160,6 +162,8 @@ __owur int tls_parse_extension(SSL *s, TLSEXT_INDEX idx, int context,
                                int *al);
 __owur int tls_parse_all_extensions(SSL *s, int context, RAW_EXTENSION *exts,
                                     X509 *x, size_t chainidx, int *al);
+__owur int should_add_extension(SSL *s, unsigned int extctx,
+                                unsigned int thisctx, int max_version);
 __owur int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
                                     X509 *x, size_t chainidx, int *al);
 
index 49949100da94bb03dd90992d3cc8c4993ccacad0..49974c9c94d472e0925a35b2760fe59d67ff97bb 100644 (file)
@@ -439,3 +439,4 @@ SSL_get0_CA_list                        439 1_1_1   EXIST::FUNCTION:
 SSL_get0_peer_CA_list                   440    1_1_1   EXIST::FUNCTION:
 SSL_CTX_add1_CA_list                    441    1_1_1   EXIST::FUNCTION:
 SSL_CTX_get0_CA_list                    442    1_1_1   EXIST::FUNCTION:
+SSL_CTX_add_custom_ext                  443    1_1_1   EXIST::FUNCTION: