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@@ -0,0 +1,169 @@
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+/* General persistent per-UID keyrings register
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+ *
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+ * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
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+ * Written by David Howells (dhowells@redhat.com)
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public Licence
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+ * as published by the Free Software Foundation; either version
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+ * 2 of the Licence, or (at your option) any later version.
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+ */
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+
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+#include <linux/user_namespace.h>
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+#include "internal.h"
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+
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+unsigned persistent_keyring_expiry = 3 * 24 * 3600; /* Expire after 3 days of non-use */
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+
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+/*
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+ * Create the persistent keyring register for the current user namespace.
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+ *
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+ * Called with the namespace's sem locked for writing.
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+ */
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+static int key_create_persistent_register(struct user_namespace *ns)
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+{
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+ struct key *reg = keyring_alloc(".persistent_register",
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+ KUIDT_INIT(0), KGIDT_INIT(0),
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+ current_cred(),
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+ ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
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+ KEY_USR_VIEW | KEY_USR_READ),
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+ KEY_ALLOC_NOT_IN_QUOTA, NULL);
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+ if (IS_ERR(reg))
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+ return PTR_ERR(reg);
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+
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+ ns->persistent_keyring_register = reg;
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+ return 0;
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+}
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+
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+/*
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+ * Create the persistent keyring for the specified user.
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+ *
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+ * Called with the namespace's sem locked for writing.
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+ */
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+static key_ref_t key_create_persistent(struct user_namespace *ns, kuid_t uid,
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+ struct keyring_index_key *index_key)
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+{
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+ struct key *persistent;
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+ key_ref_t reg_ref, persistent_ref;
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+
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+ if (!ns->persistent_keyring_register) {
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+ long err = key_create_persistent_register(ns);
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+ if (err < 0)
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+ return ERR_PTR(err);
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+ } else {
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+ reg_ref = make_key_ref(ns->persistent_keyring_register, true);
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+ persistent_ref = find_key_to_update(reg_ref, index_key);
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+ if (persistent_ref)
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+ return persistent_ref;
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+ }
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+
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+ persistent = keyring_alloc(index_key->description,
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+ uid, INVALID_GID, current_cred(),
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+ ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
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+ KEY_USR_VIEW | KEY_USR_READ),
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+ KEY_ALLOC_NOT_IN_QUOTA,
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+ ns->persistent_keyring_register);
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+ if (IS_ERR(persistent))
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+ return ERR_CAST(persistent);
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+
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+ return make_key_ref(persistent, true);
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+}
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+
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+/*
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+ * Get the persistent keyring for a specific UID and link it to the nominated
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+ * keyring.
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+ */
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+static long key_get_persistent(struct user_namespace *ns, kuid_t uid,
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+ key_ref_t dest_ref)
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+{
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+ struct keyring_index_key index_key;
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+ struct key *persistent;
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+ key_ref_t reg_ref, persistent_ref;
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+ char buf[32];
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+ long ret;
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+
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+ /* Look in the register if it exists */
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+ index_key.type = &key_type_keyring;
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+ index_key.description = buf;
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+ index_key.desc_len = sprintf(buf, "_persistent.%u", from_kuid(ns, uid));
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+
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+ if (ns->persistent_keyring_register) {
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+ reg_ref = make_key_ref(ns->persistent_keyring_register, true);
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+ down_read(&ns->persistent_keyring_register_sem);
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+ persistent_ref = find_key_to_update(reg_ref, &index_key);
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+ up_read(&ns->persistent_keyring_register_sem);
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+
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+ if (persistent_ref)
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+ goto found;
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+ }
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+
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+ /* It wasn't in the register, so we'll need to create it. We might
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+ * also need to create the register.
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+ */
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+ down_write(&ns->persistent_keyring_register_sem);
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+ persistent_ref = key_create_persistent(ns, uid, &index_key);
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+ up_write(&ns->persistent_keyring_register_sem);
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+ if (!IS_ERR(persistent_ref))
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+ goto found;
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+
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+ return PTR_ERR(persistent_ref);
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+
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+found:
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+ ret = key_task_permission(persistent_ref, current_cred(), KEY_LINK);
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+ if (ret == 0) {
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+ persistent = key_ref_to_ptr(persistent_ref);
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+ ret = key_link(key_ref_to_ptr(dest_ref), persistent);
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+ if (ret == 0) {
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+ key_set_timeout(persistent, persistent_keyring_expiry);
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+ ret = persistent->serial;
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+ }
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+ }
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+
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+ key_ref_put(persistent_ref);
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+ return ret;
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+}
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+
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+/*
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+ * Get the persistent keyring for a specific UID and link it to the nominated
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+ * keyring.
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+ */
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+long keyctl_get_persistent(uid_t _uid, key_serial_t destid)
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+{
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+ struct user_namespace *ns = current_user_ns();
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+ key_ref_t dest_ref;
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+ kuid_t uid;
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+ long ret;
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+
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+ /* -1 indicates the current user */
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+ if (_uid == (uid_t)-1) {
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+ uid = current_uid();
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+ } else {
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+ uid = make_kuid(ns, _uid);
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+ if (!uid_valid(uid))
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+ return -EINVAL;
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+
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+ /* You can only see your own persistent cache if you're not
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+ * sufficiently privileged.
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+ */
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+ if (uid_eq(uid, current_uid()) &&
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+ uid_eq(uid, current_suid()) &&
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+ uid_eq(uid, current_euid()) &&
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+ uid_eq(uid, current_fsuid()) &&
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+ !ns_capable(ns, CAP_SETUID))
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+ return -EPERM;
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+ }
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+
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+ /* There must be a destination keyring */
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+ dest_ref = lookup_user_key(destid, KEY_LOOKUP_CREATE, KEY_WRITE);
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+ if (IS_ERR(dest_ref))
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+ return PTR_ERR(dest_ref);
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+ if (key_ref_to_ptr(dest_ref)->type != &key_type_keyring) {
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+ ret = -ENOTDIR;
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+ goto out_put_dest;
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+ }
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+
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+ ret = key_get_persistent(ns, uid, dest_ref);
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+
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+out_put_dest:
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+ key_ref_put(dest_ref);
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+ return ret;
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+}
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