// SPDX-License-Identifier: GPL-2.0-or-later

  /* General persistent per-UID keyrings register
   *
   * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)

   */
  
  #include <linux/user_namespace.h>

  #include <linux/cred.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, 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, NULL,

  				   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 */

  	memset(&index_key, 0, sizeof(index_key));

  	index_key.type = &key_type_keyring;
  	index_key.description = buf;
  	index_key.desc_len = sprintf(buf, "_persistent.%u", from_kuid(ns, uid));

  	key_set_index_key(&index_key);

  
  	if (ns->persistent_keyring_register) {
  		reg_ref = make_key_ref(ns->persistent_keyring_register, true);

  		down_read(&ns->keyring_sem);

  		persistent_ref = find_key_to_update(reg_ref, &index_key);

  		up_read(&ns->keyring_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->keyring_sem);

  	persistent_ref = key_create_persistent(ns, uid, &index_key);

  	up_write(&ns->keyring_sem);

  	if (!IS_ERR(persistent_ref))
  		goto found;
  
  	return PTR_ERR(persistent_ref);
  
  found:

  	ret = key_task_permission(persistent_ref, current_cred(), KEY_NEED_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_NEED_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;
  }