1 files changed, 242 insertions, 0 deletions
diff --git a/lib/utils_keyring.c b/lib/utils_keyring.c
new file mode 100644
index 0000000..fdef674
--- /dev/null
+++ b/lib/utils_keyring.c
@@ -0,0 +1,242 @@
+/*
+ * kernel keyring utilities
+ *
+ * Copyright (C) 2016-2021 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2016-2021 Ondrej Kozina
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+
+#include "libcryptsetup.h"
+#include "utils_keyring.h"
+
+#ifndef HAVE_KEY_SERIAL_T
+#define HAVE_KEY_SERIAL_T
+typedef int32_t key_serial_t;
+#endif
+
+#ifndef ARRAY_SIZE
+# define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+#endif
+
+#ifdef KERNEL_KEYRING
+
+static const struct {
+	key_type_t type;
+	const char *type_name;
+} key_types[] = {
+	{ LOGON_KEY,	"logon" },
+	{ USER_KEY,	"user"	},
+};
+
+#include <linux/keyctl.h>
+
+/* request_key */
+static key_serial_t request_key(const char *type,
+	const char *description,
+	const char *callout_info,
+	key_serial_t keyring)
+{
+	return syscall(__NR_request_key, type, description, callout_info, keyring);
+}
+
+/* add_key */
+static key_serial_t add_key(const char *type,
+	const char *description,
+	const void *payload,
+	size_t plen,
+	key_serial_t keyring)
+{
+	return syscall(__NR_add_key, type, description, payload, plen, keyring);
+}
+
+/* keyctl_read */
+static long keyctl_read(key_serial_t key, char *buffer, size_t buflen)
+{
+	return syscall(__NR_keyctl, KEYCTL_READ, key, buffer, buflen);
+}
+
+/* keyctl_revoke */
+static long keyctl_revoke(key_serial_t key)
+{
+	return syscall(__NR_keyctl, KEYCTL_REVOKE, key);
+}
+
+/* keyctl_unlink */
+static long keyctl_unlink(key_serial_t key, key_serial_t keyring)
+{
+	return syscall(__NR_keyctl, KEYCTL_UNLINK, key, keyring);
+}
+#endif
+
+int keyring_check(void)
+{
+#ifdef KERNEL_KEYRING
+	/* logon type key descriptions must be in format "prefix:description" */
+	return syscall(__NR_request_key, "logon", "dummy", NULL, 0) == -1l && errno != ENOSYS;
+#else
+	return 0;
+#endif
+}
+
+int keyring_add_key_in_thread_keyring(key_type_t ktype, const char *key_desc, const void *key, size_t key_size)
+{
+#ifdef KERNEL_KEYRING
+	key_serial_t kid;
+	const char *type_name = key_type_name(ktype);
+
+	if (!type_name || !key_desc)
+		return -EINVAL;
+
+	kid = add_key(type_name, key_desc, key, key_size, KEY_SPEC_THREAD_KEYRING);
+	if (kid < 0)
+		return -errno;
+
+	return 0;
+#else
+	return -ENOTSUP;
+#endif
+}
+
+/* currently used in client utilities only */
+int keyring_add_key_in_user_keyring(key_type_t ktype, const char *key_desc, const void *key, size_t key_size)
+{
+#ifdef KERNEL_KEYRING
+	const char *type_name = key_type_name(ktype);
+	key_serial_t kid;
+
+	if (!type_name || !key_desc)
+		return -EINVAL;
+
+	kid = add_key(type_name, key_desc, key, key_size, KEY_SPEC_USER_KEYRING);
+	if (kid < 0)
+		return -errno;
+
+	return 0;
+#else
+	return -ENOTSUP;
+#endif
+}
+
+/* alias for the same code */
+int keyring_get_key(const char *key_desc,
+		    char **key,
+		    size_t *key_size)
+{
+	return keyring_get_passphrase(key_desc, key, key_size);
+}
+
+int keyring_get_passphrase(const char *key_desc,
+		      char **passphrase,
+		      size_t *passphrase_len)
+{
+#ifdef KERNEL_KEYRING
+	int err;
+	key_serial_t kid;
+	long ret;
+	char *buf = NULL;
+	size_t len = 0;
+
+	do
+		kid = request_key(key_type_name(USER_KEY), key_desc, NULL, 0);
+	while (kid < 0 && errno == EINTR);
+
+	if (kid < 0)
+		return -errno;
+
+	/* just get payload size */
+	ret = keyctl_read(kid, NULL, 0);
+	if (ret > 0) {
+		len = ret;
+		buf = malloc(len);
+		if (!buf)
+			return -ENOMEM;
+
+		/* retrieve actual payload data */
+		ret = keyctl_read(kid, buf, len);
+	}
+
+	if (ret < 0) {
+		err = errno;
+		if (buf)
+			crypt_safe_memzero(buf, len);
+		free(buf);
+		return -err;
+	}
+
+	*passphrase = buf;
+	*passphrase_len = len;
+
+	return 0;
+#else
+	return -ENOTSUP;
+#endif
+}
+
+static int keyring_revoke_and_unlink_key_type(const char *type_name, const char *key_desc)
+{
+#ifdef KERNEL_KEYRING
+	key_serial_t kid;
+
+	if (!type_name || !key_desc)
+		return -EINVAL;
+
+	do
+		kid = request_key(type_name, key_desc, NULL, 0);
+	while (kid < 0 && errno == EINTR);
+
+	if (kid < 0)
+		return 0;
+
+	if (keyctl_revoke(kid))
+		return -errno;
+
+	/*
+	 * best effort only. the key could have been linked
+	 * in some other keyring and its payload is now
+	 * revoked anyway.
+	 */
+	keyctl_unlink(kid, KEY_SPEC_THREAD_KEYRING);
+	keyctl_unlink(kid, KEY_SPEC_PROCESS_KEYRING);
+	keyctl_unlink(kid, KEY_SPEC_USER_KEYRING);
+
+	return 0;
+#else
+	return -ENOTSUP;
+#endif
+}
+
+const char *key_type_name(key_type_t type)
+{
+#ifdef KERNEL_KEYRING
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(key_types); i++)
+		if (type == key_types[i].type)
+			return key_types[i].type_name;
+#endif
+	return NULL;
+}
+
+int keyring_revoke_and_unlink_key(key_type_t ktype, const char *key_desc)
+{
+	return keyring_revoke_and_unlink_key_type(key_type_name(ktype), key_desc);
+}