port string_hashsum from libgcrypt to openssl^gcrypt

This allows resolved and importd to be built without libgcrypt.

Note that we now say either 'cryptographic library' or 'cryptolib'.

Co-authored-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>

TODO

@@ -433,9 +433,7 @@ Features:
 * socket units: allow creating a udev monitor socket with ListenDevices= or so,
   with matches, then activate app through that passing socket over
 
-* unify on openssl (as soon as OpenSSL 3.0 is out, and the Debian license
-  confusion is gone)
-  - port resolved over from libgcrypt (DNSSEC code)
+* unify on openssl:
   - port journald + fsprg over from libgcrypt
   - when that's done: kill gnutls support in resolved
 

meson.build

@@ -1448,18 +1448,6 @@ else
 endif
 conf.set10('HAVE_DBUS', have)
 
-default_dnssec = get_option('default-dnssec')
-if skip_deps
-        default_dnssec = 'no'
-endif
-if default_dnssec != 'no' and conf.get('HAVE_GCRYPT') == 0
-        message('default-dnssec cannot be set to yes or allow-downgrade when gcrypt is disabled. Setting default-dnssec to no.')
-        default_dnssec = 'no'
-endif
-conf.set('DEFAULT_DNSSEC_MODE',
-         'DNSSEC_' + default_dnssec.underscorify().to_upper())
-conf.set_quoted('DEFAULT_DNSSEC_MODE_STR', default_dnssec)
-
 dns_over_tls = get_option('dns-over-tls')
 if dns_over_tls != 'false'
         if dns_over_tls == 'openssl'
@@ -1535,6 +1523,18 @@ conf.set10('HAVE_OPENSSL_OR_GCRYPT',
            conf.get('HAVE_OPENSSL') == 1 or conf.get('HAVE_GCRYPT') == 1)
 lib_openssl_or_gcrypt = conf.get('PREFER_OPENSSL') == 1 ? libopenssl : libgcrypt
 
+default_dnssec = get_option('default-dnssec')
+if skip_deps
+        default_dnssec = 'no'
+endif
+if default_dnssec != 'no' and conf.get('HAVE_OPENSSL_OR_GCRYPT') == 0
+        message('default-dnssec cannot be set to yes or allow-downgrade openssl and gcrypt are disabled. Setting default-dnssec to no.')
+        default_dnssec = 'no'
+endif
+conf.set('DEFAULT_DNSSEC_MODE',
+         'DNSSEC_' + default_dnssec.underscorify().to_upper())
+conf.set_quoted('DEFAULT_DNSSEC_MODE_STR', default_dnssec)
+
 want_importd = get_option('importd')
 if want_importd != 'false'
         have = (conf.get('HAVE_LIBCURL') == 1 and

src/basic/build.c

@@ -48,7 +48,7 @@ const char* const systemd_features =
         " -SECCOMP"
 #endif
 
-        /* crypto libraries */
+        /* cryptographic libraries */
 
 #if HAVE_GCRYPT
         " +GCRYPT"

src/basic/gcrypt-util.c

@@ -18,6 +18,7 @@ void initialize_libgcrypt(bool secmem) {
         gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
 }
 
+#  if !PREFER_OPENSSL
 int string_hashsum(const char *s, size_t len, int md_algorithm, char **out) {
         _cleanup_(gcry_md_closep) gcry_md_hd_t md = NULL;
         gcry_error_t err;
@@ -47,4 +48,5 @@ int string_hashsum(const char *s, size_t len, int md_algorithm, char **out) {
         *out = enc;
         return 0;
 }
+#  endif
 #endif

src/basic/gcrypt-util.h

@@ -12,23 +12,28 @@
 #include "macro.h"
 
 void initialize_libgcrypt(bool secmem);
-int string_hashsum(const char *s, size_t len, int md_algorithm, char **out);
 
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(gcry_md_hd_t, gcry_md_close, NULL);
 #endif
 
+#if !PREFER_OPENSSL
+#  if HAVE_GCRYPT
+int string_hashsum(const char *s, size_t len, int md_algorithm, char **out);
+#  endif
+
 static inline int string_hashsum_sha224(const char *s, size_t len, char **out) {
-#if HAVE_GCRYPT
+#  if HAVE_GCRYPT
         return string_hashsum(s, len, GCRY_MD_SHA224, out);
-#else
+#  else
         return -EOPNOTSUPP;
-#endif
+#  endif
 }
 
 static inline int string_hashsum_sha256(const char *s, size_t len, char **out) {
-#if HAVE_GCRYPT
+#  if HAVE_GCRYPT
         return string_hashsum(s, len, GCRY_MD_SHA256, out);
-#else
+#  else
         return -EOPNOTSUPP;
-#endif
+#  endif
 }
+#endif

src/resolve/resolvectl.c

@@ -23,6 +23,7 @@
 #include "main-func.h"
 #include "missing_network.h"
 #include "netlink-util.h"
+#include "openssl-util.h"
 #include "pager.h"
 #include "parse-argument.h"
 #include "parse-util.h"

src/resolve/resolved-conf.c

@@ -498,14 +498,14 @@ int manager_parse_config_file(Manager *m) {
                         return r;
         }
 
-#if ! HAVE_GCRYPT
+#if !HAVE_OPENSSL_OR_GCRYPT
         if (m->dnssec_mode != DNSSEC_NO) {
-                log_warning("DNSSEC option cannot be enabled or set to allow-downgrade when systemd-resolved is built without gcrypt support. Turning off DNSSEC support.");
+                log_warning("DNSSEC option cannot be enabled or set to allow-downgrade when systemd-resolved is built without a cryptographic library. Turning off DNSSEC support.");
                 m->dnssec_mode = DNSSEC_NO;
         }
 #endif
 
-#if ! ENABLE_DNS_OVER_TLS
+#if !ENABLE_DNS_OVER_TLS
         if (m->dns_over_tls_mode != DNS_OVER_TLS_NO) {
                 log_warning("DNS-over-TLS option cannot be enabled or set to opportunistic when systemd-resolved is built without DNS-over-TLS support. Turning off DNS-over-TLS support.");
                 m->dns_over_tls_mode = DNS_OVER_TLS_NO;

src/resolve/resolved-dns-packet.c

@@ -1,7 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
 #if HAVE_GCRYPT
-#include <gcrypt.h>
+#  include <gcrypt.h>
 #endif
 
 #include "alloc-util.h"
@@ -776,7 +776,7 @@ int dns_packet_append_opt(
                 static const uint8_t rfc6975[] = {
 
                         0, 5, /* OPTION_CODE: DAU */
-#if HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600
+#if PREFER_OPENSSL || (HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600)
                         0, 7, /* LIST_LENGTH */
 #else
                         0, 6, /* LIST_LENGTH */
@@ -787,7 +787,7 @@ int dns_packet_append_opt(
                         DNSSEC_ALGORITHM_RSASHA512,
                         DNSSEC_ALGORITHM_ECDSAP256SHA256,
                         DNSSEC_ALGORITHM_ECDSAP384SHA384,
-#if HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600
+#if PREFER_OPENSSL || (HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600)
                         DNSSEC_ALGORITHM_ED25519,
 #endif
 

src/resolve/resolved-link.c

@@ -414,9 +414,9 @@ void link_set_dnssec_mode(Link *l, DnssecMode mode) {
 
         assert(l);
 
-#if ! HAVE_GCRYPT
+#if !HAVE_OPENSSL_OR_GCRYPT
         if (IN_SET(mode, DNSSEC_YES, DNSSEC_ALLOW_DOWNGRADE))
-                log_warning("DNSSEC option for the link cannot be enabled or set to allow-downgrade when systemd-resolved is built without gcrypt support. Turning off DNSSEC support.");
+                log_warning("DNSSEC option for the link cannot be enabled or set to allow-downgrade when systemd-resolved is built without a cryptographic library. Turning off DNSSEC support.");
         return;
 #endif
 

src/shared/openssl-util.c

@@ -2,6 +2,7 @@
 
 #include "openssl-util.h"
 #include "alloc-util.h"
+#include "hexdecoct.h"
 
 #if HAVE_OPENSSL
 int openssl_hash(const EVP_MD *alg,
@@ -107,4 +108,33 @@ int rsa_pkey_to_suitable_key_size(
         *ret_suitable_key_size = suitable_key_size;
         return 0;
 }
+
+#  if PREFER_OPENSSL
+int string_hashsum(
+                const char *s,
+                size_t len,
+                const EVP_MD *md_algorithm,
+                char **ret) {
+
+        uint8_t hash[EVP_MAX_MD_SIZE];
+        size_t hash_size;
+        char *enc;
+        int r;
+
+        hash_size = EVP_MD_size(md_algorithm);
+        assert(hash_size > 0);
+
+        r = openssl_hash(md_algorithm, s, len, hash, NULL);
+        if (r < 0)
+                return r;
+
+        enc = hexmem(hash, hash_size);
+        if (!enc)
+                return -ENOMEM;
+
+        *ret = enc;
+        return 0;
+
+}
+#  endif
 #endif

src/shared/openssl-util.h

@@ -62,3 +62,15 @@ typedef const char* elliptic_curve_t;
 typedef gcry_md_hd_t hash_context_t;
 #  define OPENSSL_OR_GCRYPT(a, b) (b)
 #endif
+
+#if PREFER_OPENSSL
+int string_hashsum(const char *s, size_t len, hash_algorithm_t md_algorithm, char **ret);
+
+static inline int string_hashsum_sha224(const char *s, size_t len, char **ret) {
+        return string_hashsum(s, len, EVP_sha224(), ret);
+}
+
+static inline int string_hashsum_sha256(const char *s, size_t len, char **ret) {
+        return string_hashsum(s, len, EVP_sha256(), ret);
+}
+#endif

src/test/meson.build

@@ -594,8 +594,10 @@ tests += [
 
         [['src/test/test-id128.c']],
 
-        [['src/test/test-gcrypt-util.c'],
-         [], [], [], 'HAVE_GCRYPT'],
+        [['src/test/test-cryptolib.c'],
+         [libshared],
+         [lib_openssl_or_gcrypt],
+         [], 'HAVE_OPENSSL_OR_GCRYPT'],
 
         [['src/test/test-nss-hosts.c',
           'src/test/nss-test-util.c',

src/test/test-cryptolib.c

@@ -3,25 +3,34 @@
 #include "alloc-util.h"
 #include "gcrypt-util.h"
 #include "macro.h"
+#include "openssl-util.h"
 #include "string-util.h"
 #include "tests.h"
 
 TEST(string_hashsum) {
         _cleanup_free_ char *out1 = NULL, *out2 = NULL, *out3 = NULL, *out4 = NULL;
 
-        assert_se(string_hashsum("asdf", 4, GCRY_MD_SHA224, &out1) == 0);
+        assert_se(string_hashsum("asdf", 4,
+                                 OPENSSL_OR_GCRYPT(EVP_sha224(), GCRY_MD_SHA224),
+                                 &out1) == 0);
         /* echo -n 'asdf' | sha224sum - */
         assert_se(streq(out1, "7872a74bcbf298a1e77d507cd95d4f8d96131cbbd4cdfc571e776c8a"));
 
-        assert_se(string_hashsum("asdf", 4, GCRY_MD_SHA256, &out2) == 0);
+        assert_se(string_hashsum("asdf", 4,
+                                 OPENSSL_OR_GCRYPT(EVP_sha256(), GCRY_MD_SHA256),
+                                 &out2) == 0);
         /* echo -n 'asdf' | sha256sum - */
         assert_se(streq(out2, "f0e4c2f76c58916ec258f246851bea091d14d4247a2fc3e18694461b1816e13b"));
 
-        assert_se(string_hashsum("", 0, GCRY_MD_SHA224, &out3) == 0);
+        assert_se(string_hashsum("", 0,
+                                 OPENSSL_OR_GCRYPT(EVP_sha224(), GCRY_MD_SHA224),
+                                 &out3) == 0);
         /* echo -n '' | sha224sum - */
         assert_se(streq(out3, "d14a028c2a3a2bc9476102bb288234c415a2b01f828ea62ac5b3e42f"));
 
-        assert_se(string_hashsum("", 0, GCRY_MD_SHA256, &out4) == 0);
+        assert_se(string_hashsum("", 0,
+                                 OPENSSL_OR_GCRYPT(EVP_sha256(), GCRY_MD_SHA256),
+                                 &out4) == 0);
         /* echo -n '' | sha256sum - */
         assert_se(streq(out4, "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"));
 }