Refactor TLS 1.3 cipher selection and fix SSL_get_ciphers

include/openssl/ssl.h

@@ -1690,15 +1690,27 @@ OPENSSL_EXPORT size_t SSL_get_all_standard_cipher_names(const char **out,
 // Once an equal-preference group is used, future directives must be
 // opcode-less. Inside an equal-preference group, spaces are not allowed.
 //
-// TLS 1.3 ciphers do not participate in this mechanism and instead have a
-// built-in preference order. Functions to set cipher lists do not affect TLS
-// 1.3, and functions to query the cipher list do not include TLS 1.3
-// ciphers.
+// Note: TLS 1.3 ciphersuites are only configurable via
+// |SSL_[CTX]_set_ciphersuites|. Other setter functions have no impact on
+// TLS 1.3 ciphersuites.
 
 // SSL_DEFAULT_CIPHER_LIST is the default cipher suite configuration. It is
 // substituted when a cipher string starts with 'DEFAULT'.
 #define SSL_DEFAULT_CIPHER_LIST "ALL"
 
+// TLS13_DEFAULT_CIPHER_LIST_AES_HW is the default TLS 1.3 cipher suite
+// configuration when AES hardware acceleration is enabled.
+#define TLS13_DEFAULT_CIPHER_LIST_AES_HW "TLS_AES_128_GCM_SHA256:" \
+                                          "TLS_AES_256_GCM_SHA384:" \
+                                          "TLS_CHACHA20_POLY1305_SHA256"
+
+// TLS13_DEFAULT_CIPHER_LIST_NO_AES_HW is the default TLS 1.3 cipher suite
+// configuration when no AES hardware acceleration is enabled.
+#define TLS13_DEFAULT_CIPHER_LIST_NO_AES_HW "TLS_CHACHA20_POLY1305_SHA256:" \
+                                            "TLS_AES_128_GCM_SHA256:" \
+                                            "TLS_AES_256_GCM_SHA384"
+
+
 // SSL_CTX_set_strict_cipher_list configures the cipher list for |ctx|,
 // evaluating |str| as a cipher string and returning error if |str| contains
 // anything meaningless. It returns one on success and zero on failure.
@@ -1714,7 +1726,8 @@ OPENSSL_EXPORT int SSL_CTX_set_strict_cipher_list(SSL_CTX *ctx,
 // behavior is strongly advised against and only meant for OpenSSL
 // compatibility.
 //
-// Note: this API only sets the TLSv1.2 and below ciphers.
+// Note: this API only sets the TLSv1.2 and below ciphers. If unchanged,
+// the default TLS 1.3 ciphersuites are pulled in as well.
 // Use |SSL_CTX_set_ciphersuites| to configure TLS 1.3 specific ciphers.
 OPENSSL_EXPORT int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str);
 

ssl/internal.h

@@ -714,10 +714,14 @@ const EVP_MD *ssl_get_handshake_digest(uint16_t version,
 // rejected. If false, nonsense will be silently ignored. If |config_tls13| is
 // true, only TLS 1.3 ciphers are considered in |ssl_cipher_collect_ciphers|. If
 // false, TLS 1.2 and below ciphers participate in |ssl_cipher_collect_ciphers|.
+// In every invocation, |ctx->cipher_list| is updated with any user-configured
+// or default TLS 1.3 cipher suites in |ctx->tls13_cipher_list|.
+//
 // An empty result is considered an error regardless of |strict| or
 // |config_tls13|. |has_aes_hw| indicates if the list should be ordered based on
 // having support for AES in hardware or not.
-bool ssl_create_cipher_list(UniquePtr<SSLCipherPreferenceList> *out_cipher_list,
+bool ssl_create_cipher_list(SSL_CTX *ctx,
+                            UniquePtr<SSLCipherPreferenceList> *out_cipher_list,
                             const bool has_aes_hw, const char *rule_str,
                             bool strict, bool config_tls13);
 

ssl/ssl_cipher.cc

@@ -142,6 +142,7 @@
 
 #include <assert.h>
 #include <string.h>
+#include <vector>
 
 #include <openssl/err.h>
 #include <openssl/md5.h>
@@ -1234,7 +1235,89 @@ static bool is_known_default_alias_keyword_filter_rule(const char *rule,
   return false;
 }
 
-bool ssl_create_cipher_list(UniquePtr<SSLCipherPreferenceList> *out_cipher_list,
+// update_cipher_list updates |ctx->cipher_list| by:
+// 1. Removing any existing TLS 1.3 ciphersuites
+// 2. Adding configured ciphersuites from |ctx->tls13_cipher_list|
+// 3. Configuring a new |ctx->cipher_list->in_group_flags|
+// This function maintains the ordering of ciphersuites and places TLS 1.3
+// ciphersuites at the front of the list.
+// Returns one on success and zero on failure.
+static int update_cipher_list(SSL_CTX *ctx) {
+  bssl::UniquePtr<STACK_OF(SSL_CIPHER)> tmp_cipher_list;
+  int num_removed_tls13_ciphers = 0, num_added_tls13_ciphers = 0;
+  Array<bool> updated_in_group_flags;
+
+  if (ctx->cipher_list && ctx->cipher_list->ciphers) {
+    tmp_cipher_list.reset(sk_SSL_CIPHER_dup(ctx->cipher_list->ciphers.get()));
+  } else {
+    tmp_cipher_list.reset(sk_SSL_CIPHER_new_null());
+  }
+
+  if (tmp_cipher_list == NULL) {
+    return 0;
+  }
+
+  int num_updated_tls12_ciphers = sk_SSL_CIPHER_num(tmp_cipher_list.get());
+
+  // Delete any existing TLSv1.3 ciphersuites. These will be first in the list
+  while (sk_SSL_CIPHER_num(tmp_cipher_list.get()) > 0 &&
+         SSL_CIPHER_get_min_version(sk_SSL_CIPHER_value(tmp_cipher_list.get(), 0))
+         == TLS1_3_VERSION) {
+    sk_SSL_CIPHER_delete(tmp_cipher_list.get(), 0);
+    num_removed_tls13_ciphers++;
+    num_updated_tls12_ciphers--;
+  }
+
+  // Insert the new TLSv1.3 ciphersuites with corresponding in_group_flags
+  if (ctx->tls13_cipher_list != NULL && ctx->tls13_cipher_list->ciphers != NULL) {
+    STACK_OF(SSL_CIPHER) *tls13_cipher_stack = ctx->tls13_cipher_list->ciphers.get();
+    num_added_tls13_ciphers = sk_SSL_CIPHER_num(tls13_cipher_stack);
+    for (int i = sk_SSL_CIPHER_num(tls13_cipher_stack) - 1; i >= 0; i--) {
+      const SSL_CIPHER *tls13_cipher = sk_SSL_CIPHER_value(tls13_cipher_stack, i);
+      if (!sk_SSL_CIPHER_unshift(tmp_cipher_list.get(), tls13_cipher)) {
+        return 0;
+      }
+    }
+  }
+
+  if (!updated_in_group_flags.Init(num_added_tls13_ciphers + num_updated_tls12_ciphers)) {
+    return 0;
+  }
+  std::fill(updated_in_group_flags.begin(), updated_in_group_flags.end(), false);
+
+  // Copy in_group_flags from |ctx->tls13_cipher_list|
+  if (ctx->tls13_cipher_list && ctx->tls13_cipher_list->in_group_flags) {
+    const auto& tls13_flags = ctx->tls13_cipher_list->in_group_flags;
+    // Ensure the last element in in_group_flags is 0. The last ciphersuite
+    // in a list must be the end of any group in that list.
+    if (tls13_flags[num_added_tls13_ciphers - 1] != 0) {
+      tls13_flags[num_added_tls13_ciphers - 1] = false;
+    }
+    for (int i = 0; i < num_added_tls13_ciphers; i++) {
+      updated_in_group_flags[i] = tls13_flags[i];
+    }
+  }
+
+  // Copy in_group_flags from |ctx->cipher_list|
+  if (ctx->cipher_list && ctx->cipher_list->in_group_flags) {
+    for (int i = 0; i < num_updated_tls12_ciphers; i++) {
+      updated_in_group_flags[i + num_added_tls13_ciphers] =
+        ctx->cipher_list->in_group_flags[i + num_removed_tls13_ciphers];
+    }
+  }
+
+  Span<const bool> flags_span(updated_in_group_flags.data(), updated_in_group_flags.size());
+  ctx->cipher_list = MakeUnique<SSLCipherPreferenceList>();
+  if (ctx->cipher_list == NULL) {
+    return 0;
+  }
+  ctx->cipher_list->Init(std::move(tmp_cipher_list), flags_span);
+
+  return 1;
+}
+
+bool ssl_create_cipher_list(SSL_CTX *ctx,
+                            UniquePtr<SSLCipherPreferenceList> *out_cipher_list,
                             const bool has_aes_hw, const char *rule_str,
                             bool strict, bool config_tls13) {
   // Return with error if nothing to do.
@@ -1367,6 +1450,9 @@ bool ssl_create_cipher_list(UniquePtr<SSLCipherPreferenceList> *out_cipher_list,
     return false;
   }
 
+  // Update |ctx->cipher_list| with any ciphers in |ctx->tls13_cipher_list|
+  update_cipher_list(ctx);
+
   return true;
 }
 

ssl/ssl_lib.cc

@@ -586,7 +586,16 @@ SSL_CTX *SSL_CTX_new(const SSL_METHOD *method) {
     return nullptr;
   }
 
-  if (!SSL_CTX_set_strict_cipher_list(ret.get(), SSL_DEFAULT_CIPHER_LIST) ||
+  bool has_aes_hw = EVP_has_aes_hardware();
+  char *cipher_rule;
+  if (has_aes_hw) {
+    cipher_rule = TLS13_DEFAULT_CIPHER_LIST_AES_HW;
+  } else {
+    cipher_rule = TLS13_DEFAULT_CIPHER_LIST_NO_AES_HW;
+  }
+
+  if (!SSL_CTX_set_ciphersuites(ret.get(), cipher_rule) ||
+      !SSL_CTX_set_strict_cipher_list(ret.get(), SSL_DEFAULT_CIPHER_LIST) ||
       // Lock the SSL_CTX to the specified version, for compatibility with
       // legacy uses of SSL_METHOD.
       !SSL_CTX_set_max_proto_version(ret.get(), method->version) ||
@@ -2178,15 +2187,15 @@ const char *SSL_get_cipher_list(const SSL *ssl, int n) {
 int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str) {
   const bool has_aes_hw = ctx->aes_hw_override ? ctx->aes_hw_override_value
                                                : EVP_has_aes_hardware();
-  return ssl_create_cipher_list(&ctx->cipher_list, has_aes_hw, str,
+  return ssl_create_cipher_list(ctx, &ctx->cipher_list, has_aes_hw, str,
                                 false /* not strict */,
                                 false /* don't configure TLSv1.3 ciphers */);
 }
 
 int SSL_CTX_set_strict_cipher_list(SSL_CTX *ctx, const char *str) {
   const bool has_aes_hw = ctx->aes_hw_override ? ctx->aes_hw_override_value
                                                : EVP_has_aes_hardware();
-  return ssl_create_cipher_list(&ctx->cipher_list, has_aes_hw, str,
+  return ssl_create_cipher_list(ctx, &ctx->cipher_list, has_aes_hw, str,
                                 true /* strict */,
                                 false /* don't configure TLSv1.3 ciphers */);
 }
@@ -2198,15 +2207,16 @@ int SSL_set_cipher_list(SSL *ssl, const char *str) {
   const bool has_aes_hw = ssl->config->aes_hw_override
                               ? ssl->config->aes_hw_override_value
                               : EVP_has_aes_hardware();
-  return ssl_create_cipher_list(&ssl->config->cipher_list, has_aes_hw, str,
+  return ssl_create_cipher_list(ssl->ctx.get(), &ssl->config->cipher_list, has_aes_hw, str,
                                 false /* not strict */,
                                 false /* don't configure TLSv1.3 ciphers */);
 }
 
 int SSL_CTX_set_ciphersuites(SSL_CTX *ctx, const char *str) {
   const bool has_aes_hw = ctx->aes_hw_override ? ctx->aes_hw_override_value
                                                : EVP_has_aes_hardware();
-  return ssl_create_cipher_list(&ctx->tls13_cipher_list, has_aes_hw, str,
+
+  return ssl_create_cipher_list(ctx, &ctx->tls13_cipher_list, has_aes_hw, str,
                                 false /* not strict */,
                                 true /* only configure TLSv1.3 ciphers */);
 }
@@ -2218,8 +2228,8 @@ int SSL_set_ciphersuites(SSL *ssl, const char *str) {
   const bool has_aes_hw = ssl->config->aes_hw_override
                               ? ssl->config->aes_hw_override_value
                               : EVP_has_aes_hardware();
-  return ssl_create_cipher_list(&ssl->config->cipher_list, has_aes_hw, str,
-                                false /* not strict */,
+  return ssl_create_cipher_list(ssl->ctx.get(), &ssl->config->cipher_list,
+                                has_aes_hw, str, false /* not strict */,
                                 true /* configure TLSv1.3 ciphers */);
 }
 
@@ -2230,8 +2240,8 @@ int SSL_set_strict_cipher_list(SSL *ssl, const char *str) {
   const bool has_aes_hw = ssl->config->aes_hw_override
                               ? ssl->config->aes_hw_override_value
                               : EVP_has_aes_hardware();
-  return ssl_create_cipher_list(&ssl->config->cipher_list, has_aes_hw, str,
-                                true /* strict */,
+  return ssl_create_cipher_list(ssl->ctx.get(), &ssl->config->cipher_list,
+                                has_aes_hw, str, true /* strict */,
                                 false /* don't configure TLSv1.3 ciphers */);
 }
 

ssl/ssl_test.cc

@@ -1616,6 +1616,11 @@ TEST(SSLTest, CipherRules) {
     bssl::UniquePtr<SSL_CTX> ctx(SSL_CTX_new(TLS_method()));
     ASSERT_TRUE(ctx);
 
+    // We configure default TLS 1.3 ciphersuites in |SSL_CTX| which pollute
+    // |ctx->cipher_list|. Set it to an empty list so we can test TLS 1.2
+    // configurations.
+    ASSERT_TRUE(SSL_CTX_set_ciphersuites(ctx.get(), ""));
+
     // Test lax mode.
     ASSERT_TRUE(SSL_CTX_set_cipher_list(ctx.get(), t.rule));
     EXPECT_TRUE(
@@ -1654,6 +1659,11 @@ TEST(SSLTest, CipherRules) {
     bssl::UniquePtr<SSL_CTX> ctx(SSL_CTX_new(TLS_method()));
     ASSERT_TRUE(ctx);
 
+    // We configure default TLS 1.3 ciphersuites in |SSL_CTX| which pollute
+    // |ctx->cipher_list|. Set it to an empty list so we can test TLS 1.2
+    // configurations.
+    ASSERT_TRUE(SSL_CTX_set_ciphersuites(ctx.get(), ""));
+
     EXPECT_FALSE(SSL_CTX_set_cipher_list(ctx.get(), t.rule));
     ASSERT_EQ(ERR_GET_REASON(ERR_get_error()), SSL_R_NO_CIPHER_MATCH);
     ERR_clear_error();
@@ -2823,6 +2833,85 @@ TEST(SSLTest, FindingCipher) {
   ASSERT_FALSE(cipher3);
 }
 
+TEST(SSLTest, SSLGetCiphersReturnsTLS13Default) {
+  bssl::UniquePtr<SSL_CTX> client_ctx(SSL_CTX_new(TLS_method()));
+  bssl::UniquePtr<SSL_CTX> server_ctx =
+          CreateContextWithTestCertificate(TLS_method());
+  ASSERT_TRUE(client_ctx);
+  ASSERT_TRUE(server_ctx);
+  // Configure only TLS 1.3.
+  ASSERT_TRUE(SSL_CTX_set_min_proto_version(client_ctx.get(), TLS1_3_VERSION));
+  ASSERT_TRUE(SSL_CTX_set_max_proto_version(client_ctx.get(), TLS1_3_VERSION));
+  ASSERT_TRUE(SSL_CTX_set_min_proto_version(server_ctx.get(), TLS1_3_VERSION));
+  ASSERT_TRUE(SSL_CTX_set_max_proto_version(server_ctx.get(), TLS1_3_VERSION));
+
+  bssl::UniquePtr<SSL> client, server;
+  // Have to ensure config is not shed per current implementation of SSL_get_ciphers.
+  ASSERT_TRUE(ConnectClientAndServer(&client, &server, client_ctx.get(), server_ctx.get(),
+    ClientConfig(), false));
+
+  // Ensure default TLS 1.3 Ciphersuites are present
+  const SSL_CIPHER *cipher1 = SSL_get_cipher_by_value(TLS1_3_CK_AES_128_GCM_SHA256 & 0xFFFF);
+  ASSERT_TRUE(cipher1);
+  const SSL_CIPHER *cipher2 = SSL_get_cipher_by_value(TLS1_3_CK_AES_256_GCM_SHA384 & 0xFFFF);
+  ASSERT_TRUE(cipher2);
+  const SSL_CIPHER *cipher3 = SSL_get_cipher_by_value(TLS1_3_CK_CHACHA20_POLY1305_SHA256 & 0xFFFF);
+  ASSERT_TRUE(cipher3);
+
+  STACK_OF(SSL_CIPHER) *client_ciphers = SSL_get_ciphers(client.get());
+  STACK_OF(SSL_CIPHER) *server_ciphers = SSL_get_ciphers(server.get());
+
+  ASSERT_TRUE(sk_SSL_CIPHER_find_awslc(client_ciphers, NULL, cipher1));
+  ASSERT_TRUE(sk_SSL_CIPHER_find_awslc(client_ciphers, NULL, cipher2));
+  ASSERT_TRUE(sk_SSL_CIPHER_find_awslc(client_ciphers, NULL, cipher3));
+
+  ASSERT_TRUE(sk_SSL_CIPHER_find_awslc(server_ciphers, NULL, cipher1));
+  ASSERT_TRUE(sk_SSL_CIPHER_find_awslc(server_ciphers, NULL, cipher2));
+  ASSERT_TRUE(sk_SSL_CIPHER_find_awslc(server_ciphers, NULL, cipher3));
+}
+
+TEST(SSLTest, SSLGetCiphersReturnsTLS13Custom) {
+  bssl::UniquePtr<SSL_CTX> client_ctx(SSL_CTX_new(TLS_method()));
+  bssl::UniquePtr<SSL_CTX> server_ctx =
+          CreateContextWithTestCertificate(TLS_method());
+  ASSERT_TRUE(client_ctx);
+  ASSERT_TRUE(server_ctx);
+
+  // Configure custom TLS 1.3 Ciphersuites
+  SSL_CTX_set_ciphersuites(server_ctx.get(), "TLS_AES_128_GCM_SHA256");
+  SSL_CTX_set_ciphersuites(client_ctx.get(), "TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384");
+
+  // Configure only TLS 1.3.
+  ASSERT_TRUE(SSL_CTX_set_min_proto_version(client_ctx.get(), TLS1_3_VERSION));
+  ASSERT_TRUE(SSL_CTX_set_max_proto_version(client_ctx.get(), TLS1_3_VERSION));
+  ASSERT_TRUE(SSL_CTX_set_min_proto_version(server_ctx.get(), TLS1_3_VERSION));
+  ASSERT_TRUE(SSL_CTX_set_max_proto_version(server_ctx.get(), TLS1_3_VERSION));
+
+  bssl::UniquePtr<SSL> client, server;
+  // Have to ensure config is not shed per current implementation of SSL_get_ciphers.
+  ASSERT_TRUE(ConnectClientAndServer(&client, &server, client_ctx.get(), server_ctx.get(),
+    ClientConfig(), false));
+
+  // Ensure default TLS 1.3 Ciphersuites are present
+  const SSL_CIPHER *cipher1 = SSL_get_cipher_by_value(TLS1_3_CK_AES_128_GCM_SHA256 & 0xFFFF);
+  ASSERT_TRUE(cipher1);
+  const SSL_CIPHER *cipher2 = SSL_get_cipher_by_value(TLS1_3_CK_AES_256_GCM_SHA384 & 0xFFFF);
+  ASSERT_TRUE(cipher2);
+  const SSL_CIPHER *cipher3 = SSL_get_cipher_by_value(TLS1_3_CK_CHACHA20_POLY1305_SHA256 & 0xFFFF);
+  ASSERT_TRUE(cipher3);
+
+  STACK_OF(SSL_CIPHER) *client_ciphers = SSL_get_ciphers(client.get());
+  STACK_OF(SSL_CIPHER) *server_ciphers = SSL_get_ciphers(server.get());
+
+  ASSERT_TRUE(sk_SSL_CIPHER_find_awslc(client_ciphers, NULL, cipher1));
+  ASSERT_TRUE(sk_SSL_CIPHER_find_awslc(client_ciphers, NULL, cipher2));
+  ASSERT_FALSE(sk_SSL_CIPHER_find_awslc(client_ciphers, NULL, cipher3));
+
+  ASSERT_TRUE(sk_SSL_CIPHER_find_awslc(server_ciphers, NULL, cipher1));
+  ASSERT_FALSE(sk_SSL_CIPHER_find_awslc(server_ciphers, NULL, cipher2));
+  ASSERT_FALSE(sk_SSL_CIPHER_find_awslc(server_ciphers, NULL, cipher3));
+}
+
 TEST(SSLTest, GetClientCiphersAfterHandshakeFailure1_3) {
   bssl::UniquePtr<SSL_CTX> client_ctx(SSL_CTX_new(TLS_method()));
   bssl::UniquePtr<SSL_CTX> server_ctx = CreateContextWithTestCertificate(TLS_method());
@@ -6412,17 +6501,17 @@ TEST(SSLTest, EmptyCipherList) {
   // Initially, the cipher list is not empty.
   EXPECT_NE(0u, sk_SSL_CIPHER_num(SSL_CTX_get_ciphers(ctx.get())));
 
+  // Configuring the empty cipher list with |SSL_CTX_set_ciphersuites| works
+  EXPECT_TRUE(SSL_CTX_set_ciphersuites(ctx.get(), ""));
+  EXPECT_EQ(0u, sk_SSL_CIPHER_num(ctx->tls13_cipher_list->ciphers.get()));
+  EXPECT_NE(0u, sk_SSL_CIPHER_num(SSL_CTX_get_ciphers(ctx.get())));
+
   // Configuring the empty cipher list with |SSL_CTX_set_cipher_list|
   // succeeds.
   EXPECT_TRUE(SSL_CTX_set_cipher_list(ctx.get(), ""));
   // The cipher list is updated to empty.
   EXPECT_EQ(0u, sk_SSL_CIPHER_num(SSL_CTX_get_ciphers(ctx.get())));
 
-  // Configuring the empty cipher list with |SSL_CTX_set_ciphersuites|
-  // also succeeds.
-  EXPECT_TRUE(SSL_CTX_set_ciphersuites(ctx.get(), ""));
-  EXPECT_EQ(0u, sk_SSL_CIPHER_num(SSL_CTX_get_ciphers(ctx.get())));
-
   // Configuring the empty cipher list with |SSL_CTX_set_strict_cipher_list|
   // fails.
   EXPECT_FALSE(SSL_CTX_set_strict_cipher_list(ctx.get(), ""));