Ignore cipher suites when setting cipher list

set_cipher_list() sets TLSv1.2 (and below) ciphers, and its success or
failure should not depend on whether set_ciphersuites() has been used to
setup TLSv1.3 ciphers.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7759)

ssl/ssl_lib.c

@@ -2579,6 +2579,26 @@ STACK_OF(SSL_CIPHER) *SSL_CTX_get_ciphers(const SSL_CTX *ctx)
     return NULL;
 }
 
+/*
+ * Distinguish between ciphers controlled by set_ciphersuite() and
+ * set_cipher_list() when counting.
+ */
+static int cipher_list_tls12_num(STACK_OF(SSL_CIPHER) *sk)
+{
+    int i, num = 0;
+    const SSL_CIPHER *c;
+
+    if (sk == NULL)
+        return 0;
+    for (i = 0; i < sk_SSL_CIPHER_num(sk); ++i) {
+        c = sk_SSL_CIPHER_value(sk, i);
+        if (c->min_tls >= TLS1_3_VERSION)
+            continue;
+        num++;
+    }
+    return num;
+}
+
 /** specify the ciphers to be used by default by the SSL_CTX */
 int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str)
 {
@@ -2596,7 +2616,7 @@ int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str)
      */
     if (sk == NULL)
         return 0;
-    else if (sk_SSL_CIPHER_num(sk) == 0) {
+    else if (cipher_list_tls12_num(sk) == 0) {
         SSLerr(SSL_F_SSL_CTX_SET_CIPHER_LIST, SSL_R_NO_CIPHER_MATCH);
         return 0;
     }
@@ -2614,7 +2634,7 @@ int SSL_set_cipher_list(SSL *s, const char *str)
     /* see comment in SSL_CTX_set_cipher_list */
     if (sk == NULL)
         return 0;
-    else if (sk_SSL_CIPHER_num(sk) == 0) {
+    else if (cipher_list_tls12_num(sk) == 0) {
         SSLerr(SSL_F_SSL_SET_CIPHER_LIST, SSL_R_NO_CIPHER_MATCH);
         return 0;
     }

test/cipherlist_test.c

@@ -215,9 +215,44 @@ static int test_default_cipherlist_explicit(void)
     return result;
 }
 
+/* SSL_CTX_set_cipher_list() should fail if it clears all TLSv1.2 ciphers. */
+static int test_default_cipherlist_clear(void)
+{
+    SETUP_CIPHERLIST_TEST_FIXTURE();
+    SSL *s = NULL;
+
+    if (fixture == NULL)
+        return 0;
+
+    if (!TEST_int_eq(SSL_CTX_set_cipher_list(fixture->server, "no-such"), 0))
+        goto end;
+
+    if (!TEST_int_eq(ERR_GET_REASON(ERR_get_error()), SSL_R_NO_CIPHER_MATCH))
+        goto end;
+
+    s = SSL_new(fixture->client);
+
+    if (!TEST_ptr(s))
+      goto end;
+
+    if (!TEST_int_eq(SSL_set_cipher_list(s, "no-such"), 0))
+        goto end;
+
+    if (!TEST_int_eq(ERR_GET_REASON(ERR_get_error()),
+                SSL_R_NO_CIPHER_MATCH))
+        goto end;
+
+    result = 1;
+end:
+    SSL_free(s);
+    tear_down(fixture);
+    return result;
+}
+
 int setup_tests(void)
 {
     ADD_TEST(test_default_cipherlist_implicit);
     ADD_TEST(test_default_cipherlist_explicit);
+    ADD_TEST(test_default_cipherlist_clear);
     return 1;
 }

test/clienthellotest.c

@@ -99,8 +99,9 @@ static int test_client_hello(int currtest)
          * ClientHello is already going to be quite long. To avoid getting one
          * that is too long for this test we use a restricted ciphersuite list
          */
-        if (!TEST_true(SSL_CTX_set_cipher_list(ctx, "")))
+        if (!TEST_false(SSL_CTX_set_cipher_list(ctx, "")))
             goto end;
+        ERR_clear_error();
          /* Fall through */
     case TEST_ADD_PADDING:
     case TEST_PADDING_NOT_NEEDED:

test/ssltest_old.c

@@ -1382,11 +1382,52 @@ int main(int argc, char *argv[])
         goto end;
 
     if (cipher != NULL) {
-        if (!SSL_CTX_set_cipher_list(c_ctx, cipher)
-            || !SSL_CTX_set_cipher_list(s_ctx, cipher)
-            || !SSL_CTX_set_cipher_list(s_ctx2, cipher)) {
-            ERR_print_errors(bio_err);
-            goto end;
+        if (strcmp(cipher, "") == 0) {
+            if (!SSL_CTX_set_cipher_list(c_ctx, cipher)) {
+                if (ERR_GET_REASON(ERR_peek_error()) == SSL_R_NO_CIPHER_MATCH) {
+                    ERR_clear_error();
+                } else {
+                    ERR_print_errors(bio_err);
+                    goto end;
+                }
+            } else {
+                /* Should have failed when clearing all TLSv1.2 ciphers. */
+                fprintf(stderr, "CLEARING ALL TLSv1.2 CIPHERS SHOULD FAIL\n");
+                goto end;
+            }
+
+            if (!SSL_CTX_set_cipher_list(s_ctx, cipher)) {
+                if (ERR_GET_REASON(ERR_peek_error()) == SSL_R_NO_CIPHER_MATCH) {
+                    ERR_clear_error();
+                } else {
+                    ERR_print_errors(bio_err);
+                    goto end;
+                }
+            } else {
+                /* Should have failed when clearing all TLSv1.2 ciphers. */
+                fprintf(stderr, "CLEARING ALL TLSv1.2 CIPHERS SHOULD FAIL\n");
+                goto end;
+            }
+
+            if (!SSL_CTX_set_cipher_list(s_ctx2, cipher)) {
+                if (ERR_GET_REASON(ERR_peek_error()) == SSL_R_NO_CIPHER_MATCH) {
+                    ERR_clear_error();
+                } else {
+                    ERR_print_errors(bio_err);
+                    goto end;
+                }
+            } else {
+                /* Should have failed when clearing all TLSv1.2 ciphers. */
+                fprintf(stderr, "CLEARING ALL TLSv1.2 CIPHERS SHOULD FAIL\n");
+                goto end;
+            }
+        } else {
+            if (!SSL_CTX_set_cipher_list(c_ctx, cipher)
+                    || !SSL_CTX_set_cipher_list(s_ctx, cipher)
+                    || !SSL_CTX_set_cipher_list(s_ctx2, cipher)) {
+                ERR_print_errors(bio_err);
+                goto end;
+            }
         }
     }
     if (ciphersuites != NULL) {