linux/security/keys/keyctl.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* Userspace key control operations
 *
 * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/key.h>
#include <linux/keyctl.h>
#include <linux/fs.h>
#include <linux/capability.h>
#include <linux/cred.h>
#include <linux/string.h>
#include <linux/err.h>
#include <linux/vmalloc.h>
#include <linux/security.h>
#include <linux/uio.h>
#include <linux/uaccess.h>
#include <keys/request_key_auth-type.h>
#include "internal.h"

#define KEY_MAX_DESC_SIZE …

static const unsigned char keyrings_capabilities[2] = …;

static int key_get_type_from_user(char *type,
				  const char __user *_type,
				  unsigned len)
{ … }

/*
 * Extract the description of a new key from userspace and either add it as a
 * new key to the specified keyring or update a matching key in that keyring.
 *
 * If the description is NULL or an empty string, the key type is asked to
 * generate one from the payload.
 *
 * The keyring must be writable so that we can attach the key to it.
 *
 * If successful, the new key's serial number is returned, otherwise an error
 * code is returned.
 */
SYSCALL_DEFINE5(add_key, const char __user *, _type,
		const char __user *, _description,
		const void __user *, _payload,
		size_t, plen,
		key_serial_t, ringid)
{ … }

/*
 * Search the process keyrings and keyring trees linked from those for a
 * matching key.  Keyrings must have appropriate Search permission to be
 * searched.
 *
 * If a key is found, it will be attached to the destination keyring if there's
 * one specified and the serial number of the key will be returned.
 *
 * If no key is found, /sbin/request-key will be invoked if _callout_info is
 * non-NULL in an attempt to create a key.  The _callout_info string will be
 * passed to /sbin/request-key to aid with completing the request.  If the
 * _callout_info string is "" then it will be changed to "-".
 */
SYSCALL_DEFINE4(request_key, const char __user *, _type,
		const char __user *, _description,
		const char __user *, _callout_info,
		key_serial_t, destringid)
{ … }

/*
 * Get the ID of the specified process keyring.
 *
 * The requested keyring must have search permission to be found.
 *
 * If successful, the ID of the requested keyring will be returned.
 */
long keyctl_get_keyring_ID(key_serial_t id, int create)
{ … }

/*
 * Join a (named) session keyring.
 *
 * Create and join an anonymous session keyring or join a named session
 * keyring, creating it if necessary.  A named session keyring must have Search
 * permission for it to be joined.  Session keyrings without this permit will
 * be skipped over.  It is not permitted for userspace to create or join
 * keyrings whose name begin with a dot.
 *
 * If successful, the ID of the joined session keyring will be returned.
 */
long keyctl_join_session_keyring(const char __user *_name)
{ … }

/*
 * Update a key's data payload from the given data.
 *
 * The key must grant the caller Write permission and the key type must support
 * updating for this to work.  A negative key can be positively instantiated
 * with this call.
 *
 * If successful, 0 will be returned.  If the key type does not support
 * updating, then -EOPNOTSUPP will be returned.
 */
long keyctl_update_key(key_serial_t id,
		       const void __user *_payload,
		       size_t plen)
{ … }

/*
 * Revoke a key.
 *
 * The key must be grant the caller Write or Setattr permission for this to
 * work.  The key type should give up its quota claim when revoked.  The key
 * and any links to the key will be automatically garbage collected after a
 * certain amount of time (/proc/sys/kernel/keys/gc_delay).
 *
 * Keys with KEY_FLAG_KEEP set should not be revoked.
 *
 * If successful, 0 is returned.
 */
long keyctl_revoke_key(key_serial_t id)
{ … }

/*
 * Invalidate a key.
 *
 * The key must be grant the caller Invalidate permission for this to work.
 * The key and any links to the key will be automatically garbage collected
 * immediately.
 *
 * Keys with KEY_FLAG_KEEP set should not be invalidated.
 *
 * If successful, 0 is returned.
 */
long keyctl_invalidate_key(key_serial_t id)
{ … }

/*
 * Clear the specified keyring, creating an empty process keyring if one of the
 * special keyring IDs is used.
 *
 * The keyring must grant the caller Write permission and not have
 * KEY_FLAG_KEEP set for this to work.  If successful, 0 will be returned.
 */
long keyctl_keyring_clear(key_serial_t ringid)
{ … }

/*
 * Create a link from a keyring to a key if there's no matching key in the
 * keyring, otherwise replace the link to the matching key with a link to the
 * new key.
 *
 * The key must grant the caller Link permission and the keyring must grant
 * the caller Write permission.  Furthermore, if an additional link is created,
 * the keyring's quota will be extended.
 *
 * If successful, 0 will be returned.
 */
long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
{ … }

/*
 * Unlink a key from a keyring.
 *
 * The keyring must grant the caller Write permission for this to work; the key
 * itself need not grant the caller anything.  If the last link to a key is
 * removed then that key will be scheduled for destruction.
 *
 * Keys or keyrings with KEY_FLAG_KEEP set should not be unlinked.
 *
 * If successful, 0 will be returned.
 */
long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
{ … }

/*
 * Move a link to a key from one keyring to another, displacing any matching
 * key from the destination keyring.
 *
 * The key must grant the caller Link permission and both keyrings must grant
 * the caller Write permission.  There must also be a link in the from keyring
 * to the key.  If both keyrings are the same, nothing is done.
 *
 * If successful, 0 will be returned.
 */
long keyctl_keyring_move(key_serial_t id, key_serial_t from_ringid,
			 key_serial_t to_ringid, unsigned int flags)
{ … }

/*
 * Return a description of a key to userspace.
 *
 * The key must grant the caller View permission for this to work.
 *
 * If there's a buffer, we place up to buflen bytes of data into it formatted
 * in the following way:
 *
 *	type;uid;gid;perm;description<NUL>
 *
 * If successful, we return the amount of description available, irrespective
 * of how much we may have copied into the buffer.
 */
long keyctl_describe_key(key_serial_t keyid,
			 char __user *buffer,
			 size_t buflen)
{ … }

/*
 * Search the specified keyring and any keyrings it links to for a matching
 * key.  Only keyrings that grant the caller Search permission will be searched
 * (this includes the starting keyring).  Only keys with Search permission can
 * be found.
 *
 * If successful, the found key will be linked to the destination keyring if
 * supplied and the key has Link permission, and the found key ID will be
 * returned.
 */
long keyctl_keyring_search(key_serial_t ringid,
			   const char __user *_type,
			   const char __user *_description,
			   key_serial_t destringid)
{ … }

/*
 * Call the read method
 */
static long __keyctl_read_key(struct key *key, char *buffer, size_t buflen)
{ … }

/*
 * Read a key's payload.
 *
 * The key must either grant the caller Read permission, or it must grant the
 * caller Search permission when searched for from the process keyrings.
 *
 * If successful, we place up to buflen bytes of data into the buffer, if one
 * is provided, and return the amount of data that is available in the key,
 * irrespective of how much we copied into the buffer.
 */
long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
{ … }

/*
 * Change the ownership of a key
 *
 * The key must grant the caller Setattr permission for this to work, though
 * the key need not be fully instantiated yet.  For the UID to be changed, or
 * for the GID to be changed to a group the caller is not a member of, the
 * caller must have sysadmin capability.  If either uid or gid is -1 then that
 * attribute is not changed.
 *
 * If the UID is to be changed, the new user must have sufficient quota to
 * accept the key.  The quota deduction will be removed from the old user to
 * the new user should the attribute be changed.
 *
 * If successful, 0 will be returned.
 */
long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
{ … }

/*
 * Change the permission mask on a key.
 *
 * The key must grant the caller Setattr permission for this to work, though
 * the key need not be fully instantiated yet.  If the caller does not have
 * sysadmin capability, it may only change the permission on keys that it owns.
 */
long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
{ … }

/*
 * Get the destination keyring for instantiation and check that the caller has
 * Write permission on it.
 */
static long get_instantiation_keyring(key_serial_t ringid,
				      struct request_key_auth *rka,
				      struct key **_dest_keyring)
{ … }

/*
 * Change the request_key authorisation key on the current process.
 */
static int keyctl_change_reqkey_auth(struct key *key)
{ … }

/*
 * Instantiate a key with the specified payload and link the key into the
 * destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * If successful, 0 will be returned.
 */
static long keyctl_instantiate_key_common(key_serial_t id,
				   struct iov_iter *from,
				   key_serial_t ringid)
{ … }

/*
 * Instantiate a key with the specified payload and link the key into the
 * destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * If successful, 0 will be returned.
 */
long keyctl_instantiate_key(key_serial_t id,
			    const void __user *_payload,
			    size_t plen,
			    key_serial_t ringid)
{ … }

/*
 * Instantiate a key with the specified multipart payload and link the key into
 * the destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * If successful, 0 will be returned.
 */
long keyctl_instantiate_key_iov(key_serial_t id,
				const struct iovec __user *_payload_iov,
				unsigned ioc,
				key_serial_t ringid)
{ … }

/*
 * Negatively instantiate the key with the given timeout (in seconds) and link
 * the key into the destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * The key and any links to the key will be automatically garbage collected
 * after the timeout expires.
 *
 * Negative keys are used to rate limit repeated request_key() calls by causing
 * them to return -ENOKEY until the negative key expires.
 *
 * If successful, 0 will be returned.
 */
long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
{ … }

/*
 * Negatively instantiate the key with the given timeout (in seconds) and error
 * code and link the key into the destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * The key and any links to the key will be automatically garbage collected
 * after the timeout expires.
 *
 * Negative keys are used to rate limit repeated request_key() calls by causing
 * them to return the specified error code until the negative key expires.
 *
 * If successful, 0 will be returned.
 */
long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
		       key_serial_t ringid)
{ … }

/*
 * Read or set the default keyring in which request_key() will cache keys and
 * return the old setting.
 *
 * If a thread or process keyring is specified then it will be created if it
 * doesn't yet exist.  The old setting will be returned if successful.
 */
long keyctl_set_reqkey_keyring(int reqkey_defl)
{ … }

/*
 * Set or clear the timeout on a key.
 *
 * Either the key must grant the caller Setattr permission or else the caller
 * must hold an instantiation authorisation token for the key.
 *
 * The timeout is either 0 to clear the timeout, or a number of seconds from
 * the current time.  The key and any links to the key will be automatically
 * garbage collected after the timeout expires.
 *
 * Keys with KEY_FLAG_KEEP set should not be timed out.
 *
 * If successful, 0 is returned.
 */
long keyctl_set_timeout(key_serial_t id, unsigned timeout)
{ … }

/*
 * Assume (or clear) the authority to instantiate the specified key.
 *
 * This sets the authoritative token currently in force for key instantiation.
 * This must be done for a key to be instantiated.  It has the effect of making
 * available all the keys from the caller of the request_key() that created a
 * key to request_key() calls made by the caller of this function.
 *
 * The caller must have the instantiation key in their process keyrings with a
 * Search permission grant available to the caller.
 *
 * If the ID given is 0, then the setting will be cleared and 0 returned.
 *
 * If the ID given has a matching an authorisation key, then that key will be
 * set and its ID will be returned.  The authorisation key can be read to get
 * the callout information passed to request_key().
 */
long keyctl_assume_authority(key_serial_t id)
{ … }

/*
 * Get a key's the LSM security label.
 *
 * The key must grant the caller View permission for this to work.
 *
 * If there's a buffer, then up to buflen bytes of data will be placed into it.
 *
 * If successful, the amount of information available will be returned,
 * irrespective of how much was copied (including the terminal NUL).
 */
long keyctl_get_security(key_serial_t keyid,
			 char __user *buffer,
			 size_t buflen)
{ … }

/*
 * Attempt to install the calling process's session keyring on the process's
 * parent process.
 *
 * The keyring must exist and must grant the caller LINK permission, and the
 * parent process must be single-threaded and must have the same effective
 * ownership as this process and mustn't be SUID/SGID.
 *
 * The keyring will be emplaced on the parent when it next resumes userspace.
 *
 * If successful, 0 will be returned.
 */
long keyctl_session_to_parent(void)
{ … }

/*
 * Apply a restriction to a given keyring.
 *
 * The caller must have Setattr permission to change keyring restrictions.
 *
 * The requested type name may be a NULL pointer to reject all attempts
 * to link to the keyring.  In this case, _restriction must also be NULL.
 * Otherwise, both _type and _restriction must be non-NULL.
 *
 * Returns 0 if successful.
 */
long keyctl_restrict_keyring(key_serial_t id, const char __user *_type,
			     const char __user *_restriction)
{ … }

#ifdef CONFIG_KEY_NOTIFICATIONS
/*
 * Watch for changes to a key.
 *
 * The caller must have View permission to watch a key or keyring.
 */
long keyctl_watch_key(key_serial_t id, int watch_queue_fd, int watch_id)
{ … }
#endif /* CONFIG_KEY_NOTIFICATIONS */

/*
 * Get keyrings subsystem capabilities.
 */
long keyctl_capabilities(unsigned char __user *_buffer, size_t buflen)
{ … }

/*
 * The key control system call
 */
SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
		unsigned long, arg4, unsigned long, arg5)
{ … }