[rt42272] also warn on use of MD5 for rndc keys

bin/confgen/rndc-confgen.c

@@ -73,7 +73,7 @@ Usage:\n\
  %s [-a] [-b bits] [-c keyfile] [-k keyname] [-p port] [-r randomfile] \
 [-s addr] [-t chrootdir] [-u user]\n\
   -a:		 generate just the key clause and write it to keyfile (%s)\n\
-  -A alg:	 algorithm (default hmac-md5)\n\
+  -A alg:	 algorithm (default hmac-md5 (deprecated and will change))\n\
   -b bits:	 from 1 through 512, default 256; total length of the secret\n\
   -c keyfile:	 specify an alternate key file (requires -a)\n\
   -k keyname:	 the name as it will be used  in named.conf and rndc.conf\n\
@@ -115,6 +115,7 @@ main(int argc, char **argv) {
 	const char *randomfile = NULL;
 	const char *serveraddr = NULL;
 	dns_secalg_t alg;
+	isc_boolean_t algset = ISC_FALSE;
 	const char *algname;
 	char *p;
 	int ch;
@@ -153,6 +154,7 @@ main(int argc, char **argv) {
 			keyonly = ISC_TRUE;
 			break;
 		case 'A':
+			algset = ISC_TRUE;
 			algname = isc_commandline_argument;
 			alg = alg_fromtext(algname);
 			if (alg == DST_ALG_UNKNOWN)
@@ -225,6 +227,19 @@ main(int argc, char **argv) {
 	if (argc > 0)
 		usage(1);
 
+	if (alg == DST_ALG_HMACMD5) {
+		if (algset) {
+			fprintf(stderr,
+				"warning: use of hmac-md5 for RNDC keys "
+				"is deprecated; consider hmac-sha256.\n");
+		} else {
+			fprintf(stderr,
+				"warning: the default algorithm hmac-md5 "
+				"is deprecated and will be\n"
+				"changed in a future release\n")
+		}
+	}
+
 	if (keysize < 0)
 		keysize = alg_bits(alg);
 	algname = alg_totext(alg);

bin/confgen/rndc-confgen.docbook

@@ -128,8 +128,12 @@
           <para>
             Specifies the algorithm to use for the TSIG key.  Available
             choices are: hmac-md5, hmac-sha1, hmac-sha224, hmac-sha256,
-            hmac-sha384 and hmac-sha512.  The default is hmac-md5 or
-            if MD5 was disabled hmac-sha256.
+            hmac-sha384 and hmac-sha512.  The default is hmac-md5, or
+            if MD5 was disabled at compile time, hmac-sha256.
+          </para>
+          <para>
+            Note: Use of hmac-md5 is no longer recommended, and the default
+            value will be changed to hmac-sha256 in a future release.
           </para>
         </listitem>
       </varlistentry>

doc/arm/notes.xml

@@ -489,6 +489,16 @@
 	  a future release. [RT #42272]
 	</para>
       </listitem>
+      <listitem>
+	<para>
+	  The use of HMAC-MD5 for RNDC keys is no longer recommended.
+	  For compatibility, this is still the default algorithm generated
+	  by <command>rndc-confgen</command>, but it will print a
+	  warning message. The default algorithm in
+	  <command>rndc-confgen</command> will be changed to HMAC-SHA256
+	  in a future release. [RT #42272]
+	</para>
+      </listitem>
     </itemizedlist>
   </section>