From 83b889c238282b210f874a3ad81bb56299767495 Mon Sep 17 00:00:00 2001
From: Petr Mensik <pemensik@redhat.com>
Date: Mon, 5 Aug 2019 11:54:03 +0200
Subject: [PATCH] Allow explicit disabling of autodisabled MD5

Default security policy might include explicitly disabled RSAMD5
algorithm. Current FIPS code automatically disables in FIPS mode. But if
RSAMD5 is included in security policy, it fails to start, because that
algorithm is not recognized. Allow it disabled, but fail on any
other usage.
---
 bin/named/server.c |  4 ++--
 lib/bind9/check.c  |  4 ++++
 lib/dns/rcode.c    | 33 +++++++++++++++------------------
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/bin/named/server.c b/bin/named/server.c
index 5b57371..51702ab 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -1547,12 +1547,12 @@ disable_algorithms(const cfg_obj_t *disabled, dns_resolver_t *resolver) {
 		r.length = strlen(r.base);
 
 		result = dns_secalg_fromtext(&alg, &r);
-		if (result != ISC_R_SUCCESS) {
+		if (result != ISC_R_SUCCESS && result != ISC_R_DISABLED) {
 			uint8_t ui;
 			result = isc_parse_uint8(&ui, r.base, 10);
 			alg = ui;
 		}
-		if (result != ISC_R_SUCCESS) {
+		if (result != ISC_R_SUCCESS && result != ISC_R_DISABLED) {
 			cfg_obj_log(cfg_listelt_value(element),
 				    ns_g_lctx, ISC_LOG_ERROR,
 				    "invalid algorithm");
diff --git a/lib/bind9/check.c b/lib/bind9/check.c
index e0803d4..8023784 100644
--- a/lib/bind9/check.c
+++ b/lib/bind9/check.c
@@ -302,6 +302,10 @@ disabled_algorithms(const cfg_obj_t *disabled, isc_log_t *logctx) {
 		r.length = strlen(r.base);
 
 		tresult = dns_secalg_fromtext(&alg, &r);
+		if (tresult == ISC_R_DISABLED) {
+			// Recognize disabled algorithms, disable it explicitly
+			tresult = ISC_R_SUCCESS;
+		}
 		if (tresult != ISC_R_SUCCESS) {
 			cfg_obj_log(cfg_listelt_value(element), logctx,
 				    ISC_LOG_ERROR, "invalid algorithm '%s'",
diff --git a/lib/dns/rcode.c b/lib/dns/rcode.c
index f51d548..c49b8d1 100644
--- a/lib/dns/rcode.c
+++ b/lib/dns/rcode.c
@@ -126,7 +126,6 @@
 #endif
 
 #define SECALGNAMES \
-	MD5_SECALGNAMES \
 	DH_SECALGNAMES \
 	DSA_SECALGNAMES \
 	{ DNS_KEYALG_ECC, "ECC", 0 }, \
@@ -178,6 +177,7 @@ static struct tbl rcodes[] = { RCODENAMES ERCODENAMES };
 static struct tbl tsigrcodes[] = { RCODENAMES TSIGRCODENAMES };
 static struct tbl certs[] = { CERTNAMES };
 static struct tbl secalgs[] = { SECALGNAMES };
+static struct tbl md5_secalgs[] = { MD5_SECALGNAMES };
 static struct tbl secprotos[] = { SECPROTONAMES };
 static struct tbl hashalgs[] = { HASHALGNAMES };
 static struct tbl dsdigests[] = { DSDIGESTNAMES };
@@ -358,33 +358,30 @@ dns_cert_totext(dns_cert_t cert, isc_buffer_t *target) {
 	return (dns_mnemonic_totext(cert, target, certs));
 }
 
-static inline struct tbl *
-secalgs_tbl_start() {
-	struct tbl *algs = secalgs;
-
-#ifndef PK11_MD5_DISABLE
-	if (!isc_md5_available()) {
-		while (algs->name != NULL &&
-		       algs->value == DNS_KEYALG_RSAMD5)
-			++algs;
-	}
-#endif
-	return algs;
-}
-
 isc_result_t
 dns_secalg_fromtext(dns_secalg_t *secalgp, isc_textregion_t *source) {
 	unsigned int value;
+	isc_result_t result;
 
-	RETERR(dns_mnemonic_fromtext(&value, source,
-	                             secalgs_tbl_start(), 0xff));
+	result = dns_mnemonic_fromtext(&value, source,
+	                               secalgs, 0xff);
+	if (result != ISC_R_SUCCESS) {
+		result = dns_mnemonic_fromtext(&value, source,
+	                                       md5_secalgs, 0xff);
+		if (result != ISC_R_SUCCESS) {
+			return (result);
+		} else if (!isc_md5_available()) {
+			*secalgp = value;
+			return (ISC_R_DISABLED);
+		}
+	}
 	*secalgp = value;
 	return (ISC_R_SUCCESS);
 }
 
 isc_result_t
 dns_secalg_totext(dns_secalg_t secalg, isc_buffer_t *target) {
-	return (dns_mnemonic_totext(secalg, target, secalgs_tbl_start()));
+	return (dns_mnemonic_totext(secalg, target, secalgs));
 }
 
 void
-- 
2.20.1