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-rw-r--r--security/keys/persistent.c167
1 files changed, 167 insertions, 0 deletions
diff --git a/security/keys/persistent.c b/security/keys/persistent.c
new file mode 100644
index 000000000000..0ad3ee283781
--- /dev/null
+++ b/security/keys/persistent.c
@@ -0,0 +1,167 @@
+/* General persistent per-UID keyrings register
+ *
+ * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/user_namespace.h>
+#include "internal.h"
+
+unsigned persistent_keyring_expiry = 3 * 24 * 3600; /* Expire after 3 days of non-use */
+
+/*
+ * Create the persistent keyring register for the current user namespace.
+ *
+ * Called with the namespace's sem locked for writing.
+ */
+static int key_create_persistent_register(struct user_namespace *ns)
+{
+ struct key *reg = keyring_alloc(".persistent_register",
+ KUIDT_INIT(0), KGIDT_INIT(0),
+ current_cred(),
+ ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ),
+ KEY_ALLOC_NOT_IN_QUOTA, NULL);
+ if (IS_ERR(reg))
+ return PTR_ERR(reg);
+
+ ns->persistent_keyring_register = reg;
+ return 0;
+}
+
+/*
+ * Create the persistent keyring for the specified user.
+ *
+ * Called with the namespace's sem locked for writing.
+ */
+static key_ref_t key_create_persistent(struct user_namespace *ns, kuid_t uid,
+ struct keyring_index_key *index_key)
+{
+ struct key *persistent;
+ key_ref_t reg_ref, persistent_ref;
+
+ if (!ns->persistent_keyring_register) {
+ long err = key_create_persistent_register(ns);
+ if (err < 0)
+ return ERR_PTR(err);
+ } else {
+ reg_ref = make_key_ref(ns->persistent_keyring_register, true);
+ persistent_ref = find_key_to_update(reg_ref, index_key);
+ if (persistent_ref)
+ return persistent_ref;
+ }
+
+ persistent = keyring_alloc(index_key->description,
+ uid, INVALID_GID, current_cred(),
+ ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ),
+ KEY_ALLOC_NOT_IN_QUOTA,
+ ns->persistent_keyring_register);
+ if (IS_ERR(persistent))
+ return ERR_CAST(persistent);
+
+ return make_key_ref(persistent, true);
+}
+
+/*
+ * Get the persistent keyring for a specific UID and link it to the nominated
+ * keyring.
+ */
+static long key_get_persistent(struct user_namespace *ns, kuid_t uid,
+ key_ref_t dest_ref)
+{
+ struct keyring_index_key index_key;
+ struct key *persistent;
+ key_ref_t reg_ref, persistent_ref;
+ char buf[32];
+ long ret;
+
+ /* Look in the register if it exists */
+ index_key.type = &key_type_keyring;
+ index_key.description = buf;
+ index_key.desc_len = sprintf(buf, "_persistent.%u", from_kuid(ns, uid));
+
+ if (ns->persistent_keyring_register) {
+ reg_ref = make_key_ref(ns->persistent_keyring_register, true);
+ down_read(&ns->persistent_keyring_register_sem);
+ persistent_ref = find_key_to_update(reg_ref, &index_key);
+ up_read(&ns->persistent_keyring_register_sem);
+
+ if (persistent_ref)
+ goto found;
+ }
+
+ /* It wasn't in the register, so we'll need to create it. We might
+ * also need to create the register.
+ */
+ down_write(&ns->persistent_keyring_register_sem);
+ persistent_ref = key_create_persistent(ns, uid, &index_key);
+ up_write(&ns->persistent_keyring_register_sem);
+ if (!IS_ERR(persistent_ref))
+ goto found;
+
+ return PTR_ERR(persistent_ref);
+
+found:
+ ret = key_task_permission(persistent_ref, current_cred(), KEY_LINK);
+ if (ret == 0) {
+ persistent = key_ref_to_ptr(persistent_ref);
+ ret = key_link(key_ref_to_ptr(dest_ref), persistent);
+ if (ret == 0) {
+ key_set_timeout(persistent, persistent_keyring_expiry);
+ ret = persistent->serial;
+ }
+ }
+
+ key_ref_put(persistent_ref);
+ return ret;
+}
+
+/*
+ * Get the persistent keyring for a specific UID and link it to the nominated
+ * keyring.
+ */
+long keyctl_get_persistent(uid_t _uid, key_serial_t destid)
+{
+ struct user_namespace *ns = current_user_ns();
+ key_ref_t dest_ref;
+ kuid_t uid;
+ long ret;
+
+ /* -1 indicates the current user */
+ if (_uid == (uid_t)-1) {
+ uid = current_uid();
+ } else {
+ uid = make_kuid(ns, _uid);
+ if (!uid_valid(uid))
+ return -EINVAL;
+
+ /* You can only see your own persistent cache if you're not
+ * sufficiently privileged.
+ */
+ if (!uid_eq(uid, current_uid()) &&
+ !uid_eq(uid, current_euid()) &&
+ !ns_capable(ns, CAP_SETUID))
+ return -EPERM;
+ }
+
+ /* There must be a destination keyring */
+ dest_ref = lookup_user_key(destid, KEY_LOOKUP_CREATE, KEY_WRITE);
+ if (IS_ERR(dest_ref))
+ return PTR_ERR(dest_ref);
+ if (key_ref_to_ptr(dest_ref)->type != &key_type_keyring) {
+ ret = -ENOTDIR;
+ goto out_put_dest;
+ }
+
+ ret = key_get_persistent(ns, uid, dest_ref);
+
+out_put_dest:
+ key_ref_put(dest_ref);
+ return ret;
+}

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