Merge pull request #31261 from bluca/repart_engine

repart: support engines and providers

docs/ENVIRONMENT.md

@@ -129,6 +129,14 @@ All tools:
 * `$SYSTEMD_VERITY_SHARING=0` — if set, sharing dm-verity devices by
   using a stable `<ROOTHASH>-verity` device mapper name will be disabled.
 
+* `$SYSTEMD_OPENSSL_KEY_LOADER`— when using OpenSSL to load a key via an engine
+  or a provider, can be used to force the usage of one or the other interface.
+  Set to 'engine' to force the usage of the old engine API, and to 'provider'
+  force the usage of the new provider API. If unset, the provider will be tried
+  first and the engine as a fallback if that fails. Providers are the new OpenSSL
+  3 API, but there are very few if any in a production-ready state, so engines
+  are still needed.
+
 `systemctl`:
 
 * `$SYSTEMCTL_FORCE_BUS=1` — if set, do not connect to PID 1's private D-Bus

man/systemd-repart.xml

@@ -354,6 +354,16 @@
         <xi:include href="version-info.xml" xpointer="v252"/></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><option>--private-key-uri=</option></term>
+
+        <listitem><para>Takes a URI-like string referring to a private key, that will be passed to OpenSSL's
+        "engine" or "provider" logic. Configures the signing key to use when creating verity signature
+        partitions with the <varname>Verity=signature</varname> setting in partition files.</para>
+
+        <xi:include href="version-info.xml" xpointer="v256"/></listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><option>--certificate=</option></term>
 
@@ -616,6 +626,27 @@ systemd-confext refresh</programlisting>
       <citerefentry><refentrytitle>systemd-confext</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
     </example>
 
+    <example>
+      <title>Generate a system extension image and sign it via PKCS11</title>
+
+      <para>The following creates a system extension DDI (sysext) for an
+      <filename>/usr/foo</filename> update and signs it with a hardware token via PKCS11.</para>
+
+      <programlisting>mkdir tree tree/usr tree/usr/lib/extension-release.d
+echo "Hello World" > tree/usr/foo
+cat > tree/usr/lib/extension-release.d/extension-release.my-foo &lt;&lt;EOF
+ID=fedora
+VERSION_ID=38
+IMAGE_ID=my-foo
+IMAGE_VERSION=7
+EOF
+systemd-repart --make-ddi=sysext --private-key-uri="pkcs11:model=PKCS%2315%20emulated;manufacturer=piv_II;serial=0123456789abcdef;token=Some%20Cert" --certificate=cert.crt -s tree/ /var/lib/extensions/my-foo.sysext.raw
+systemd-sysext refresh</programlisting>
+
+      <para>The DDI generated that way may be applied to the system with
+      <citerefentry><refentrytitle>systemd-sysext</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
+    </example>
+
   </refsect1>
 
   <refsect1>

src/partition/repart.c

@@ -6506,6 +6506,7 @@ static int help(void) {
 }
 
 static int parse_argv(int argc, char *argv[]) {
+        _cleanup_free_ char *private_key = NULL, *private_key_uri = NULL;
 
         enum {
                 ARG_VERSION = 0x100,
@@ -6526,6 +6527,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_JSON,
                 ARG_KEY_FILE,
                 ARG_PRIVATE_KEY,
+                ARG_PRIVATE_KEY_URI,
                 ARG_CERTIFICATE,
                 ARG_TPM2_DEVICE,
                 ARG_TPM2_DEVICE_KEY,
@@ -6566,6 +6568,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "json",                 required_argument, NULL, ARG_JSON                 },
                 { "key-file",             required_argument, NULL, ARG_KEY_FILE             },
                 { "private-key",          required_argument, NULL, ARG_PRIVATE_KEY          },
+                { "private-key-uri",      required_argument, NULL, ARG_PRIVATE_KEY_URI      },
                 { "certificate",          required_argument, NULL, ARG_CERTIFICATE          },
                 { "tpm2-device",          required_argument, NULL, ARG_TPM2_DEVICE          },
                 { "tpm2-device-key",      required_argument, NULL, ARG_TPM2_DEVICE_KEY      },
@@ -6751,20 +6754,14 @@ static int parse_argv(int argc, char *argv[]) {
                 }
 
                 case ARG_PRIVATE_KEY: {
-                        _cleanup_(erase_and_freep) char *k = NULL;
-                        size_t n = 0;
-
-                        r = read_full_file_full(
-                                        AT_FDCWD, optarg, UINT64_MAX, SIZE_MAX,
-                                        READ_FULL_FILE_SECURE|READ_FULL_FILE_WARN_WORLD_READABLE|READ_FULL_FILE_CONNECT_SOCKET,
-                                        NULL,
-                                        &k, &n);
+                        r = free_and_strdup_warn(&private_key, optarg);
                         if (r < 0)
-                                return log_error_errno(r, "Failed to read key file '%s': %m", optarg);
+                                return r;
+                        break;
+                }
 
-                        EVP_PKEY_free(arg_private_key);
-                        arg_private_key = NULL;
-                        r = parse_private_key(k, n, &arg_private_key);
+                case ARG_PRIVATE_KEY_URI: {
+                        r = free_and_strdup_warn(&private_key_uri, optarg);
                         if (r < 0)
                                 return r;
                         break;
@@ -7101,6 +7098,38 @@ static int parse_argv(int argc, char *argv[]) {
                         *p = gpt_partition_type_override_architecture(*p, arg_architecture);
         }
 
+        if (private_key && private_key_uri)
+                return log_error_errno(
+                                SYNTHETIC_ERRNO(EINVAL),
+                                "Cannot specify both --private-key= and --private-key-uri=.");
+
+        if (private_key) {
+                _cleanup_(erase_and_freep) char *k = NULL;
+                size_t n = 0;
+
+                r = read_full_file_full(
+                                AT_FDCWD, private_key, UINT64_MAX, SIZE_MAX,
+                                READ_FULL_FILE_SECURE|READ_FULL_FILE_WARN_WORLD_READABLE|READ_FULL_FILE_CONNECT_SOCKET,
+                                NULL,
+                                &k, &n);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to read key file '%s': %m", private_key);
+
+                r = parse_private_key(k, n, &arg_private_key);
+                if (r < 0)
+                        return r;
+        } else if (private_key_uri) {
+                /* This must happen after parse_x509_certificate() is called above, otherwise
+                 * signing later will get stuck as the parsed private key won't have the
+                 * certificate, so this block cannot be inline in ARG_PRIVATE_KEY. */
+                r = openssl_load_key_from_token(private_key_uri, &arg_private_key);
+                if (r < 0)
+                        return log_error_errno(
+                                        r,
+                                        "Failed to load key '%s' from OpenSSL provider: %m",
+                                        private_key);
+        }
+
         return 1;
 }
 

src/shared/openssl-util.c

@@ -1298,6 +1298,107 @@ int pkey_generate_volume_keys(
                 return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Unsupported public key type: %s", OBJ_nid2sn(type));
         }
 }
+
+static int load_key_from_provider(const char *provider, const char *private_key_uri, EVP_PKEY **ret) {
+
+        assert(provider);
+        assert(private_key_uri);
+        assert(ret);
+
+#if OPENSSL_VERSION_MAJOR >= 3
+        /* Load the provider so that this can work without any custom written configuration in /etc/.
+         * Also load the 'default' as that seems to be the recommendation. */
+        if (!OSSL_PROVIDER_try_load(/* ctx= */ NULL, provider, /* retain_fallbacks= */ true))
+                return log_openssl_errors("Failed to load OpenSSL provider '%s'", provider);
+        if (!OSSL_PROVIDER_try_load(/* ctx= */ NULL, "default", /* retain_fallbacks= */ true))
+                return log_openssl_errors("Failed to load OpenSSL provider 'default'");
+
+        _cleanup_(OSSL_STORE_closep) OSSL_STORE_CTX *store = OSSL_STORE_open(
+                        private_key_uri,
+                        /* ui_method= */ NULL,
+                        /* ui_data= */ NULL,
+                        /* post_process= */ NULL,
+                        /* post_process_data= */ NULL);
+        if (!store)
+                return log_openssl_errors("Failed to open OpenSSL store via '%s'", private_key_uri);
+
+        _cleanup_(OSSL_STORE_INFO_freep) OSSL_STORE_INFO *info = OSSL_STORE_load(store);
+        if (!info)
+                return log_openssl_errors("Failed to load OpenSSL store via '%s'", private_key_uri);
+
+        _cleanup_(EVP_PKEY_freep) EVP_PKEY *private_key = OSSL_STORE_INFO_get1_PKEY(info);
+        if (!private_key)
+                return log_openssl_errors("Failed to load private key via '%s'", private_key_uri);
+
+        *ret = TAKE_PTR(private_key);
+
+        return 0;
+#else
+        return -EOPNOTSUPP;
+#endif
+}
+
+static int load_key_from_engine(const char *engine, const char *private_key_uri, EVP_PKEY **ret) {
+
+        assert(engine);
+        assert(private_key_uri);
+        assert(ret);
+
+        DISABLE_WARNING_DEPRECATED_DECLARATIONS;
+        _cleanup_(ENGINE_freep) ENGINE *e = ENGINE_by_id(engine);
+        if (!e)
+                return log_openssl_errors("Failed to load signing engine '%s'", engine);
+
+        if (ENGINE_init(e) == 0)
+                return log_openssl_errors("Failed to initialize signing engine '%s'", engine);
+
+        _cleanup_(EVP_PKEY_freep) EVP_PKEY *private_key = ENGINE_load_private_key(
+                        e,
+                        private_key_uri,
+                        /* ui_method= */ NULL,
+                        /* callback_data= */ NULL);
+        if (!private_key)
+                return log_openssl_errors("Failed to load private key from '%s'", private_key_uri);
+        REENABLE_WARNING;
+
+        *ret = TAKE_PTR(private_key);
+
+        return 0;
+}
+
+int openssl_load_key_from_token(const char *private_key_uri, EVP_PKEY **ret) {
+        _cleanup_free_ char *provider = NULL;
+        const char *colon, *e;
+        int r;
+
+        assert(private_key_uri);
+
+        colon = strchr(private_key_uri, ':');
+        if (!colon)
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Invalid URI '%s'", private_key_uri);
+
+        provider = strndup(private_key_uri, colon - private_key_uri);
+        if (!provider)
+                return log_oom_debug();
+
+        e = secure_getenv("SYSTEMD_OPENSSL_KEY_LOADER");
+        if (e) {
+                if (streq(e, "provider"))
+                        r = load_key_from_provider(provider, private_key_uri, ret);
+                else if (streq(e, "engine"))
+                        r = load_key_from_engine(provider, private_key_uri, ret);
+                else
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Invalid value for SYSTEMD_OPENSSL_KEY_LOADER: %s", e);
+        } else {
+                r = load_key_from_provider(provider, private_key_uri, ret);
+                if (r < 0) {
+                        log_debug_errno(r, "Failed to load key from provider '%s', falling back to engine", provider);
+                        r = load_key_from_engine(provider, private_key_uri, ret);
+                }
+        }
+
+        return r;
+}
 #endif
 
 int x509_fingerprint(X509 *cert, uint8_t buffer[static SHA256_DIGEST_SIZE]) {

src/shared/openssl-util.h

@@ -11,6 +11,7 @@
 #  include <openssl/bio.h>
 #  include <openssl/bn.h>
 #  include <openssl/crypto.h>
+#  include <openssl/engine.h>
 #  include <openssl/err.h>
 #  include <openssl/evp.h>
 #  include <openssl/opensslv.h>
@@ -25,6 +26,8 @@
 #    include <openssl/core_names.h>
 #    include <openssl/kdf.h>
 #    include <openssl/param_build.h>
+#    include <openssl/provider.h>
+#    include <openssl/store.h>
 #  endif
 
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL_MACRO(void*, OPENSSL_free, NULL);
@@ -41,6 +44,9 @@ DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(SSL*, SSL_free, NULL);
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(BIO*, BIO_free, NULL);
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(EVP_MD_CTX*, EVP_MD_CTX_free, NULL);
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(ASN1_OCTET_STRING*, ASN1_OCTET_STRING_free, NULL);
+DISABLE_WARNING_DEPRECATED_DECLARATIONS;
+DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(ENGINE*, ENGINE_free, NULL);
+REENABLE_WARNING;
 #if OPENSSL_VERSION_MAJOR >= 3
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(EVP_CIPHER*, EVP_CIPHER_free, NULL);
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(EVP_KDF*, EVP_KDF_free, NULL);
@@ -50,6 +56,8 @@ DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(EVP_MAC_CTX*, EVP_MAC_CTX_free, NULL);
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(EVP_MD*, EVP_MD_free, NULL);
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(OSSL_PARAM*, OSSL_PARAM_free, NULL);
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(OSSL_PARAM_BLD*, OSSL_PARAM_BLD_free, NULL);
+DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(OSSL_STORE_CTX*, OSSL_STORE_close, NULL);
+DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(OSSL_STORE_INFO*, OSSL_STORE_INFO_free, NULL);
 #else
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(EC_KEY*, EC_KEY_free, NULL);
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(HMAC_CTX*, HMAC_CTX_free, NULL);
@@ -115,6 +123,8 @@ int pubkey_fingerprint(EVP_PKEY *pk, const EVP_MD *md, void **ret, size_t *ret_s
 
 int digest_and_sign(const EVP_MD *md, EVP_PKEY *privkey, const void *data, size_t size, void **ret, size_t *ret_size);
 
+int openssl_load_key_from_token(const char *private_key_uri, EVP_PKEY **ret);
+
 #else
 
 typedef struct X509 X509;
@@ -130,6 +140,10 @@ static inline void *EVP_PKEY_free(EVP_PKEY *p) {
         return NULL;
 }
 
+static inline int openssl_load_key_from_token(const char *private_key_uri, EVP_PKEY **ret) {
+        return -EOPNOTSUPP;
+}
+
 #endif
 
 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(X509*, X509_free, NULL);