Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1215 insertions, 0 deletions

diff --git a/security/keys/key.c b/security/keys/key.c
new file mode 100644
index 000000000..e65240641
--- /dev/null
+++ b/security/keys/key.c
@@ -0,0 +1,1215 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Basic authentication token and access key management
+ *
+ * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/poison.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+#include <linux/workqueue.h>
+#include <linux/random.h>
+#include <linux/ima.h>
+#include <linux/err.h>
+#include "internal.h"
+
+struct kmem_cache *key_jar;
+struct rb_root		key_serial_tree; /* tree of keys indexed by serial */
+DEFINE_SPINLOCK(key_serial_lock);
+
+struct rb_root	key_user_tree; /* tree of quota records indexed by UID */
+DEFINE_SPINLOCK(key_user_lock);
+
+unsigned int key_quota_root_maxkeys = 1000000;	/* root's key count quota */
+unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
+unsigned int key_quota_maxkeys = 200;		/* general key count quota */
+unsigned int key_quota_maxbytes = 20000;	/* general key space quota */
+
+static LIST_HEAD(key_types_list);
+static DECLARE_RWSEM(key_types_sem);
+
+/* We serialise key instantiation and link */
+DEFINE_MUTEX(key_construction_mutex);
+
+#ifdef KEY_DEBUGGING
+void __key_check(const struct key *key)
+{
+	printk("__key_check: key %p {%08x} should be {%08x}\n",
+	       key, key->magic, KEY_DEBUG_MAGIC);
+	BUG();
+}
+#endif
+
+/*
+ * Get the key quota record for a user, allocating a new record if one doesn't
+ * already exist.
+ */
+struct key_user *key_user_lookup(kuid_t uid)
+{
+	struct key_user *candidate = NULL, *user;
+	struct rb_node *parent, **p;
+
+try_again:
+	parent = NULL;
+	p = &key_user_tree.rb_node;
+	spin_lock(&key_user_lock);
+
+	/* search the tree for a user record with a matching UID */
+	while (*p) {
+		parent = *p;
+		user = rb_entry(parent, struct key_user, node);
+
+		if (uid_lt(uid, user->uid))
+			p = &(*p)->rb_left;
+		else if (uid_gt(uid, user->uid))
+			p = &(*p)->rb_right;
+		else
+			goto found;
+	}
+
+	/* if we get here, we failed to find a match in the tree */
+	if (!candidate) {
+		/* allocate a candidate user record if we don't already have
+		 * one */
+		spin_unlock(&key_user_lock);
+
+		user = NULL;
+		candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
+		if (unlikely(!candidate))
+			goto out;
+
+		/* the allocation may have scheduled, so we need to repeat the
+		 * search lest someone else added the record whilst we were
+		 * asleep */
+		goto try_again;
+	}
+
+	/* if we get here, then the user record still hadn't appeared on the
+	 * second pass - so we use the candidate record */
+	refcount_set(&candidate->usage, 1);
+	atomic_set(&candidate->nkeys, 0);
+	atomic_set(&candidate->nikeys, 0);
+	candidate->uid = uid;
+	candidate->qnkeys = 0;
+	candidate->qnbytes = 0;
+	spin_lock_init(&candidate->lock);
+	mutex_init(&candidate->cons_lock);
+
+	rb_link_node(&candidate->node, parent, p);
+	rb_insert_color(&candidate->node, &key_user_tree);
+	spin_unlock(&key_user_lock);
+	user = candidate;
+	goto out;
+
+	/* okay - we found a user record for this UID */
+found:
+	refcount_inc(&user->usage);
+	spin_unlock(&key_user_lock);
+	kfree(candidate);
+out:
+	return user;
+}
+
+/*
+ * Dispose of a user structure
+ */
+void key_user_put(struct key_user *user)
+{
+	if (refcount_dec_and_lock(&user->usage, &key_user_lock)) {
+		rb_erase(&user->node, &key_user_tree);
+		spin_unlock(&key_user_lock);
+
+		kfree(user);
+	}
+}
+
+/*
+ * Allocate a serial number for a key.  These are assigned randomly to avoid
+ * security issues through covert channel problems.
+ */
+static inline void key_alloc_serial(struct key *key)
+{
+	struct rb_node *parent, **p;
+	struct key *xkey;
+
+	/* propose a random serial number and look for a hole for it in the
+	 * serial number tree */
+	do {
+		get_random_bytes(&key->serial, sizeof(key->serial));
+
+		key->serial >>= 1; /* negative numbers are not permitted */
+	} while (key->serial < 3);
+
+	spin_lock(&key_serial_lock);
+
+attempt_insertion:
+	parent = NULL;
+	p = &key_serial_tree.rb_node;
+
+	while (*p) {
+		parent = *p;
+		xkey = rb_entry(parent, struct key, serial_node);
+
+		if (key->serial < xkey->serial)
+			p = &(*p)->rb_left;
+		else if (key->serial > xkey->serial)
+			p = &(*p)->rb_right;
+		else
+			goto serial_exists;
+	}
+
+	/* we've found a suitable hole - arrange for this key to occupy it */
+	rb_link_node(&key->serial_node, parent, p);
+	rb_insert_color(&key->serial_node, &key_serial_tree);
+
+	spin_unlock(&key_serial_lock);
+	return;
+
+	/* we found a key with the proposed serial number - walk the tree from
+	 * that point looking for the next unused serial number */
+serial_exists:
+	for (;;) {
+		key->serial++;
+		if (key->serial < 3) {
+			key->serial = 3;
+			goto attempt_insertion;
+		}
+
+		parent = rb_next(parent);
+		if (!parent)
+			goto attempt_insertion;
+
+		xkey = rb_entry(parent, struct key, serial_node);
+		if (key->serial < xkey->serial)
+			goto attempt_insertion;
+	}
+}
+
+/**
+ * key_alloc - Allocate a key of the specified type.
+ * @type: The type of key to allocate.
+ * @desc: The key description to allow the key to be searched out.
+ * @uid: The owner of the new key.
+ * @gid: The group ID for the new key's group permissions.
+ * @cred: The credentials specifying UID namespace.
+ * @perm: The permissions mask of the new key.
+ * @flags: Flags specifying quota properties.
+ * @restrict_link: Optional link restriction for new keyrings.
+ *
+ * Allocate a key of the specified type with the attributes given.  The key is
+ * returned in an uninstantiated state and the caller needs to instantiate the
+ * key before returning.
+ *
+ * The restrict_link structure (if not NULL) will be freed when the
+ * keyring is destroyed, so it must be dynamically allocated.
+ *
+ * The user's key count quota is updated to reflect the creation of the key and
+ * the user's key data quota has the default for the key type reserved.  The
+ * instantiation function should amend this as necessary.  If insufficient
+ * quota is available, -EDQUOT will be returned.
+ *
+ * The LSM security modules can prevent a key being created, in which case
+ * -EACCES will be returned.
+ *
+ * Returns a pointer to the new key if successful and an error code otherwise.
+ *
+ * Note that the caller needs to ensure the key type isn't uninstantiated.
+ * Internally this can be done by locking key_types_sem.  Externally, this can
+ * be done by either never unregistering the key type, or making sure
+ * key_alloc() calls don't race with module unloading.
+ */
+struct key *key_alloc(struct key_type *type, const char *desc,
+		      kuid_t uid, kgid_t gid, const struct cred *cred,
+		      key_perm_t perm, unsigned long flags,
+		      struct key_restriction *restrict_link)
+{
+	struct key_user *user = NULL;
+	struct key *key;
+	size_t desclen, quotalen;
+	int ret;
+
+	key = ERR_PTR(-EINVAL);
+	if (!desc || !*desc)
+		goto error;
+
+	if (type->vet_description) {
+		ret = type->vet_description(desc);
+		if (ret < 0) {
+			key = ERR_PTR(ret);
+			goto error;
+		}
+	}
+
+	desclen = strlen(desc);
+	quotalen = desclen + 1 + type->def_datalen;
+
+	/* get hold of the key tracking for this user */
+	user = key_user_lookup(uid);
+	if (!user)
+		goto no_memory_1;
+
+	/* check that the user's quota permits allocation of another key and
+	 * its description */
+	if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
+		unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
+			key_quota_root_maxkeys : key_quota_maxkeys;
+		unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
+			key_quota_root_maxbytes : key_quota_maxbytes;
+
+		spin_lock(&user->lock);
+		if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
+			if (user->qnkeys + 1 > maxkeys ||
+			    user->qnbytes + quotalen > maxbytes ||
+			    user->qnbytes + quotalen < user->qnbytes)
+				goto no_quota;
+		}
+
+		user->qnkeys++;
+		user->qnbytes += quotalen;
+		spin_unlock(&user->lock);
+	}
+
+	/* allocate and initialise the key and its description */
+	key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
+	if (!key)
+		goto no_memory_2;
+
+	key->index_key.desc_len = desclen;
+	key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
+	if (!key->index_key.description)
+		goto no_memory_3;
+	key->index_key.type = type;
+	key_set_index_key(&key->index_key);
+
+	refcount_set(&key->usage, 1);
+	init_rwsem(&key->sem);
+	lockdep_set_class(&key->sem, &type->lock_class);
+	key->user = user;
+	key->quotalen = quotalen;
+	key->datalen = type->def_datalen;
+	key->uid = uid;
+	key->gid = gid;
+	key->perm = perm;
+	key->expiry = TIME64_MAX;
+	key->restrict_link = restrict_link;
+	key->last_used_at = ktime_get_real_seconds();
+
+	if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
+		key->flags |= 1 << KEY_FLAG_IN_QUOTA;
+	if (flags & KEY_ALLOC_BUILT_IN)
+		key->flags |= 1 << KEY_FLAG_BUILTIN;
+	if (flags & KEY_ALLOC_UID_KEYRING)
+		key->flags |= 1 << KEY_FLAG_UID_KEYRING;
+	if (flags & KEY_ALLOC_SET_KEEP)
+		key->flags |= 1 << KEY_FLAG_KEEP;
+
+#ifdef KEY_DEBUGGING
+	key->magic = KEY_DEBUG_MAGIC;
+#endif
+
+	/* let the security module know about the key */
+	ret = security_key_alloc(key, cred, flags);
+	if (ret < 0)
+		goto security_error;
+
+	/* publish the key by giving it a serial number */
+	refcount_inc(&key->domain_tag->usage);
+	atomic_inc(&user->nkeys);
+	key_alloc_serial(key);
+
+error:
+	return key;
+
+security_error:
+	kfree(key->description);
+	kmem_cache_free(key_jar, key);
+	if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
+		spin_lock(&user->lock);
+		user->qnkeys--;
+		user->qnbytes -= quotalen;
+		spin_unlock(&user->lock);
+	}
+	key_user_put(user);
+	key = ERR_PTR(ret);
+	goto error;
+
+no_memory_3:
+	kmem_cache_free(key_jar, key);
+no_memory_2:
+	if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
+		spin_lock(&user->lock);
+		user->qnkeys--;
+		user->qnbytes -= quotalen;
+		spin_unlock(&user->lock);
+	}
+	key_user_put(user);
+no_memory_1:
+	key = ERR_PTR(-ENOMEM);
+	goto error;
+
+no_quota:
+	spin_unlock(&user->lock);
+	key_user_put(user);
+	key = ERR_PTR(-EDQUOT);
+	goto error;
+}
+EXPORT_SYMBOL(key_alloc);
+
+/**
+ * key_payload_reserve - Adjust data quota reservation for the key's payload
+ * @key: The key to make the reservation for.
+ * @datalen: The amount of data payload the caller now wants.
+ *
+ * Adjust the amount of the owning user's key data quota that a key reserves.
+ * If the amount is increased, then -EDQUOT may be returned if there isn't
+ * enough free quota available.
+ *
+ * If successful, 0 is returned.
+ */
+int key_payload_reserve(struct key *key, size_t datalen)
+{
+	int delta = (int)datalen - key->datalen;
+	int ret = 0;
+
+	key_check(key);
+
+	/* contemplate the quota adjustment */
+	if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
+		unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
+			key_quota_root_maxbytes : key_quota_maxbytes;
+
+		spin_lock(&key->user->lock);
+
+		if (delta > 0 &&
+		    (key->user->qnbytes + delta > maxbytes ||
+		     key->user->qnbytes + delta < key->user->qnbytes)) {
+			ret = -EDQUOT;
+		}
+		else {
+			key->user->qnbytes += delta;
+			key->quotalen += delta;
+		}
+		spin_unlock(&key->user->lock);
+	}
+
+	/* change the recorded data length if that didn't generate an error */
+	if (ret == 0)
+		key->datalen = datalen;
+
+	return ret;
+}
+EXPORT_SYMBOL(key_payload_reserve);
+
+/*
+ * Change the key state to being instantiated.
+ */
+static void mark_key_instantiated(struct key *key, int reject_error)
+{
+	/* Commit the payload before setting the state; barrier versus
+	 * key_read_state().
+	 */
+	smp_store_release(&key->state,
+			  (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
+}
+
+/*
+ * Instantiate a key and link it into the target keyring atomically.  Must be
+ * called with the target keyring's semaphore writelocked.  The target key's
+ * semaphore need not be locked as instantiation is serialised by
+ * key_construction_mutex.
+ */
+static int __key_instantiate_and_link(struct key *key,
+				      struct key_preparsed_payload *prep,
+				      struct key *keyring,
+				      struct key *authkey,
+				      struct assoc_array_edit **_edit)
+{
+	int ret, awaken;
+
+	key_check(key);
+	key_check(keyring);
+
+	awaken = 0;
+	ret = -EBUSY;
+
+	mutex_lock(&key_construction_mutex);
+
+	/* can't instantiate twice */
+	if (key->state == KEY_IS_UNINSTANTIATED) {
+		/* instantiate the key */
+		ret = key->type->instantiate(key, prep);
+
+		if (ret == 0) {
+			/* mark the key as being instantiated */
+			atomic_inc(&key->user->nikeys);
+			mark_key_instantiated(key, 0);
+			notify_key(key, NOTIFY_KEY_INSTANTIATED, 0);
+
+			if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
+				awaken = 1;
+
+			/* and link it into the destination keyring */
+			if (keyring) {
+				if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
+					set_bit(KEY_FLAG_KEEP, &key->flags);
+
+				__key_link(keyring, key, _edit);
+			}
+
+			/* disable the authorisation key */
+			if (authkey)
+				key_invalidate(authkey);
+
+			key_set_expiry(key, prep->expiry);
+		}
+	}
+
+	mutex_unlock(&key_construction_mutex);
+
+	/* wake up anyone waiting for a key to be constructed */
+	if (awaken)
+		wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
+
+	return ret;
+}
+
+/**
+ * key_instantiate_and_link - Instantiate a key and link it into the keyring.
+ * @key: The key to instantiate.
+ * @data: The data to use to instantiate the keyring.
+ * @datalen: The length of @data.
+ * @keyring: Keyring to create a link in on success (or NULL).
+ * @authkey: The authorisation token permitting instantiation.
+ *
+ * Instantiate a key that's in the uninstantiated state using the provided data
+ * and, if successful, link it in to the destination keyring if one is
+ * supplied.
+ *
+ * If successful, 0 is returned, the authorisation token is revoked and anyone
+ * waiting for the key is woken up.  If the key was already instantiated,
+ * -EBUSY will be returned.
+ */
+int key_instantiate_and_link(struct key *key,
+			     const void *data,
+			     size_t datalen,
+			     struct key *keyring,
+			     struct key *authkey)
+{
+	struct key_preparsed_payload prep;
+	struct assoc_array_edit *edit = NULL;
+	int ret;
+
+	memset(&prep, 0, sizeof(prep));
+	prep.orig_description = key->description;
+	prep.data = data;
+	prep.datalen = datalen;
+	prep.quotalen = key->type->def_datalen;
+	prep.expiry = TIME64_MAX;
+	if (key->type->preparse) {
+		ret = key->type->preparse(&prep);
+		if (ret < 0)
+			goto error;
+	}
+
+	if (keyring) {
+		ret = __key_link_lock(keyring, &key->index_key);
+		if (ret < 0)
+			goto error;
+
+		ret = __key_link_begin(keyring, &key->index_key, &edit);
+		if (ret < 0)
+			goto error_link_end;
+
+		if (keyring->restrict_link && keyring->restrict_link->check) {
+			struct key_restriction *keyres = keyring->restrict_link;
+
+			ret = keyres->check(keyring, key->type, &prep.payload,
+					    keyres->key);
+			if (ret < 0)
+				goto error_link_end;
+		}
+	}
+
+	ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
+
+error_link_end:
+	if (keyring)
+		__key_link_end(keyring, &key->index_key, edit);
+
+error:
+	if (key->type->preparse)
+		key->type->free_preparse(&prep);
+	return ret;
+}
+
+EXPORT_SYMBOL(key_instantiate_and_link);
+
+/**
+ * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
+ * @key: The key to instantiate.
+ * @timeout: The timeout on the negative key.
+ * @error: The error to return when the key is hit.
+ * @keyring: Keyring to create a link in on success (or NULL).
+ * @authkey: The authorisation token permitting instantiation.
+ *
+ * Negatively instantiate a key that's in the uninstantiated state and, if
+ * successful, set its timeout and stored error and link it in to the
+ * destination keyring if one is supplied.  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 stored error code (typically ENOKEY) until the negative
+ * key expires.
+ *
+ * If successful, 0 is returned, the authorisation token is revoked and anyone
+ * waiting for the key is woken up.  If the key was already instantiated,
+ * -EBUSY will be returned.
+ */
+int key_reject_and_link(struct key *key,
+			unsigned timeout,
+			unsigned error,
+			struct key *keyring,
+			struct key *authkey)
+{
+	struct assoc_array_edit *edit = NULL;
+	int ret, awaken, link_ret = 0;
+
+	key_check(key);
+	key_check(keyring);
+
+	awaken = 0;
+	ret = -EBUSY;
+
+	if (keyring) {
+		if (keyring->restrict_link)
+			return -EPERM;
+
+		link_ret = __key_link_lock(keyring, &key->index_key);
+		if (link_ret == 0) {
+			link_ret = __key_link_begin(keyring, &key->index_key, &edit);
+			if (link_ret < 0)
+				__key_link_end(keyring, &key->index_key, edit);
+		}
+	}
+
+	mutex_lock(&key_construction_mutex);
+
+	/* can't instantiate twice */
+	if (key->state == KEY_IS_UNINSTANTIATED) {
+		/* mark the key as being negatively instantiated */
+		atomic_inc(&key->user->nikeys);
+		mark_key_instantiated(key, -error);
+		notify_key(key, NOTIFY_KEY_INSTANTIATED, -error);
+		key_set_expiry(key, ktime_get_real_seconds() + timeout);
+
+		if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
+			awaken = 1;
+
+		ret = 0;
+
+		/* and link it into the destination keyring */
+		if (keyring && link_ret == 0)
+			__key_link(keyring, key, &edit);
+
+		/* disable the authorisation key */
+		if (authkey)
+			key_invalidate(authkey);
+	}
+
+	mutex_unlock(&key_construction_mutex);
+
+	if (keyring && link_ret == 0)
+		__key_link_end(keyring, &key->index_key, edit);
+
+	/* wake up anyone waiting for a key to be constructed */
+	if (awaken)
+		wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
+
+	return ret == 0 ? link_ret : ret;
+}
+EXPORT_SYMBOL(key_reject_and_link);
+
+/**
+ * key_put - Discard a reference to a key.
+ * @key: The key to discard a reference from.
+ *
+ * Discard a reference to a key, and when all the references are gone, we
+ * schedule the cleanup task to come and pull it out of the tree in process
+ * context at some later time.
+ */
+void key_put(struct key *key)
+{
+	if (key) {
+		key_check(key);
+
+		if (refcount_dec_and_test(&key->usage))
+			schedule_work(&key_gc_work);
+	}
+}
+EXPORT_SYMBOL(key_put);
+
+/*
+ * Find a key by its serial number.
+ */
+struct key *key_lookup(key_serial_t id)
+{
+	struct rb_node *n;
+	struct key *key;
+
+	spin_lock(&key_serial_lock);
+
+	/* search the tree for the specified key */
+	n = key_serial_tree.rb_node;
+	while (n) {
+		key = rb_entry(n, struct key, serial_node);
+
+		if (id < key->serial)
+			n = n->rb_left;
+		else if (id > key->serial)
+			n = n->rb_right;
+		else
+			goto found;
+	}
+
+not_found:
+	key = ERR_PTR(-ENOKEY);
+	goto error;
+
+found:
+	/* A key is allowed to be looked up only if someone still owns a
+	 * reference to it - otherwise it's awaiting the gc.
+	 */
+	if (!refcount_inc_not_zero(&key->usage))
+		goto not_found;
+
+error:
+	spin_unlock(&key_serial_lock);
+	return key;
+}
+
+/*
+ * Find and lock the specified key type against removal.
+ *
+ * We return with the sem read-locked if successful.  If the type wasn't
+ * available -ENOKEY is returned instead.
+ */
+struct key_type *key_type_lookup(const char *type)
+{
+	struct key_type *ktype;
+
+	down_read(&key_types_sem);
+
+	/* look up the key type to see if it's one of the registered kernel
+	 * types */
+	list_for_each_entry(ktype, &key_types_list, link) {
+		if (strcmp(ktype->name, type) == 0)
+			goto found_kernel_type;
+	}
+
+	up_read(&key_types_sem);
+	ktype = ERR_PTR(-ENOKEY);
+
+found_kernel_type:
+	return ktype;
+}
+
+void key_set_timeout(struct key *key, unsigned timeout)
+{
+	time64_t expiry = TIME64_MAX;
+
+	/* make the changes with the locks held to prevent races */
+	down_write(&key->sem);
+
+	if (timeout > 0)
+		expiry = ktime_get_real_seconds() + timeout;
+	key_set_expiry(key, expiry);
+
+	up_write(&key->sem);
+}
+EXPORT_SYMBOL_GPL(key_set_timeout);
+
+/*
+ * Unlock a key type locked by key_type_lookup().
+ */
+void key_type_put(struct key_type *ktype)
+{
+	up_read(&key_types_sem);
+}
+
+/*
+ * Attempt to update an existing key.
+ *
+ * The key is given to us with an incremented refcount that we need to discard
+ * if we get an error.
+ */
+static inline key_ref_t __key_update(key_ref_t key_ref,
+				     struct key_preparsed_payload *prep)
+{
+	struct key *key = key_ref_to_ptr(key_ref);
+	int ret;
+
+	/* need write permission on the key to update it */
+	ret = key_permission(key_ref, KEY_NEED_WRITE);
+	if (ret < 0)
+		goto error;
+
+	ret = -EEXIST;
+	if (!key->type->update)
+		goto error;
+
+	down_write(&key->sem);
+
+	ret = key->type->update(key, prep);
+	if (ret == 0) {
+		/* Updating a negative key positively instantiates it */
+		mark_key_instantiated(key, 0);
+		notify_key(key, NOTIFY_KEY_UPDATED, 0);
+	}
+
+	up_write(&key->sem);
+
+	if (ret < 0)
+		goto error;
+out:
+	return key_ref;
+
+error:
+	key_put(key);
+	key_ref = ERR_PTR(ret);
+	goto out;
+}
+
+/**
+ * key_create_or_update - Update or create and instantiate a key.
+ * @keyring_ref: A pointer to the destination keyring with possession flag.
+ * @type: The type of key.
+ * @description: The searchable description for the key.
+ * @payload: The data to use to instantiate or update the key.
+ * @plen: The length of @payload.
+ * @perm: The permissions mask for a new key.
+ * @flags: The quota flags for a new key.
+ *
+ * Search the destination keyring for a key of the same description and if one
+ * is found, update it, otherwise create and instantiate a new one and create a
+ * link to it from that keyring.
+ *
+ * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
+ * concocted.
+ *
+ * Returns a pointer to the new key if successful, -ENODEV if the key type
+ * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
+ * caller isn't permitted to modify the keyring or the LSM did not permit
+ * creation of the key.
+ *
+ * On success, the possession flag from the keyring ref will be tacked on to
+ * the key ref before it is returned.
+ */
+key_ref_t key_create_or_update(key_ref_t keyring_ref,
+			       const char *type,
+			       const char *description,
+			       const void *payload,
+			       size_t plen,
+			       key_perm_t perm,
+			       unsigned long flags)
+{
+	struct keyring_index_key index_key = {
+		.description	= description,
+	};
+	struct key_preparsed_payload prep;
+	struct assoc_array_edit *edit = NULL;
+	const struct cred *cred = current_cred();
+	struct key *keyring, *key = NULL;
+	key_ref_t key_ref;
+	int ret;
+	struct key_restriction *restrict_link = NULL;
+
+	/* look up the key type to see if it's one of the registered kernel
+	 * types */
+	index_key.type = key_type_lookup(type);
+	if (IS_ERR(index_key.type)) {
+		key_ref = ERR_PTR(-ENODEV);
+		goto error;
+	}
+
+	key_ref = ERR_PTR(-EINVAL);
+	if (!index_key.type->instantiate ||
+	    (!index_key.description && !index_key.type->preparse))
+		goto error_put_type;
+
+	keyring = key_ref_to_ptr(keyring_ref);
+
+	key_check(keyring);
+
+	if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
+		restrict_link = keyring->restrict_link;
+
+	key_ref = ERR_PTR(-ENOTDIR);
+	if (keyring->type != &key_type_keyring)
+		goto error_put_type;
+
+	memset(&prep, 0, sizeof(prep));
+	prep.orig_description = description;
+	prep.data = payload;
+	prep.datalen = plen;
+	prep.quotalen = index_key.type->def_datalen;
+	prep.expiry = TIME64_MAX;
+	if (index_key.type->preparse) {
+		ret = index_key.type->preparse(&prep);
+		if (ret < 0) {
+			key_ref = ERR_PTR(ret);
+			goto error_free_prep;
+		}
+		if (!index_key.description)
+			index_key.description = prep.description;
+		key_ref = ERR_PTR(-EINVAL);
+		if (!index_key.description)
+			goto error_free_prep;
+	}
+	index_key.desc_len = strlen(index_key.description);
+	key_set_index_key(&index_key);
+
+	ret = __key_link_lock(keyring, &index_key);
+	if (ret < 0) {
+		key_ref = ERR_PTR(ret);
+		goto error_free_prep;
+	}
+
+	ret = __key_link_begin(keyring, &index_key, &edit);
+	if (ret < 0) {
+		key_ref = ERR_PTR(ret);
+		goto error_link_end;
+	}
+
+	if (restrict_link && restrict_link->check) {
+		ret = restrict_link->check(keyring, index_key.type,
+					   &prep.payload, restrict_link->key);
+		if (ret < 0) {
+			key_ref = ERR_PTR(ret);
+			goto error_link_end;
+		}
+	}
+
+	/* if we're going to allocate a new key, we're going to have
+	 * to modify the keyring */
+	ret = key_permission(keyring_ref, KEY_NEED_WRITE);
+	if (ret < 0) {
+		key_ref = ERR_PTR(ret);
+		goto error_link_end;
+	}
+
+	/* if it's possible to update this type of key, search for an existing
+	 * key of the same type and description in the destination keyring and
+	 * update that instead if possible
+	 */
+	if (index_key.type->update) {
+		key_ref = find_key_to_update(keyring_ref, &index_key);
+		if (key_ref)
+			goto found_matching_key;
+	}
+
+	/* if the client doesn't provide, decide on the permissions we want */
+	if (perm == KEY_PERM_UNDEF) {
+		perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
+		perm |= KEY_USR_VIEW;
+
+		if (index_key.type->read)
+			perm |= KEY_POS_READ;
+
+		if (index_key.type == &key_type_keyring ||
+		    index_key.type->update)
+			perm |= KEY_POS_WRITE;
+	}
+
+	/* allocate a new key */
+	key = key_alloc(index_key.type, index_key.description,
+			cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
+	if (IS_ERR(key)) {
+		key_ref = ERR_CAST(key);
+		goto error_link_end;
+	}
+
+	/* instantiate it and link it into the target keyring */
+	ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
+	if (ret < 0) {
+		key_put(key);
+		key_ref = ERR_PTR(ret);
+		goto error_link_end;
+	}
+
+	ima_post_key_create_or_update(keyring, key, payload, plen,
+				      flags, true);
+
+	key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
+
+error_link_end:
+	__key_link_end(keyring, &index_key, edit);
+error_free_prep:
+	if (index_key.type->preparse)
+		index_key.type->free_preparse(&prep);
+error_put_type:
+	key_type_put(index_key.type);
+error:
+	return key_ref;
+
+ found_matching_key:
+	/* we found a matching key, so we're going to try to update it
+	 * - we can drop the locks first as we have the key pinned
+	 */
+	__key_link_end(keyring, &index_key, edit);
+
+	key = key_ref_to_ptr(key_ref);
+	if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
+		ret = wait_for_key_construction(key, true);
+		if (ret < 0) {
+			key_ref_put(key_ref);
+			key_ref = ERR_PTR(ret);
+			goto error_free_prep;
+		}
+	}
+
+	key_ref = __key_update(key_ref, &prep);
+
+	if (!IS_ERR(key_ref))
+		ima_post_key_create_or_update(keyring, key,
+					      payload, plen,
+					      flags, false);
+
+	goto error_free_prep;
+}
+EXPORT_SYMBOL(key_create_or_update);
+
+/**
+ * key_update - Update a key's contents.
+ * @key_ref: The pointer (plus possession flag) to the key.
+ * @payload: The data to be used to update the key.
+ * @plen: The length of @payload.
+ *
+ * Attempt to update the contents of a key with the given payload data.  The
+ * caller must be granted Write permission on the key.  Negative keys can be
+ * instantiated by this method.
+ *
+ * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
+ * type does not support updating.  The key type may return other errors.
+ */
+int key_update(key_ref_t key_ref, const void *payload, size_t plen)
+{
+	struct key_preparsed_payload prep;
+	struct key *key = key_ref_to_ptr(key_ref);
+	int ret;
+
+	key_check(key);
+
+	/* the key must be writable */
+	ret = key_permission(key_ref, KEY_NEED_WRITE);
+	if (ret < 0)
+		return ret;
+
+	/* attempt to update it if supported */
+	if (!key->type->update)
+		return -EOPNOTSUPP;
+
+	memset(&prep, 0, sizeof(prep));
+	prep.data = payload;
+	prep.datalen = plen;
+	prep.quotalen = key->type->def_datalen;
+	prep.expiry = TIME64_MAX;
+	if (key->type->preparse) {
+		ret = key->type->preparse(&prep);
+		if (ret < 0)
+			goto error;
+	}
+
+	down_write(&key->sem);
+
+	ret = key->type->update(key, &prep);
+	if (ret == 0) {
+		/* Updating a negative key positively instantiates it */
+		mark_key_instantiated(key, 0);
+		notify_key(key, NOTIFY_KEY_UPDATED, 0);
+	}
+
+	up_write(&key->sem);
+
+error:
+	if (key->type->preparse)
+		key->type->free_preparse(&prep);
+	return ret;
+}
+EXPORT_SYMBOL(key_update);
+
+/**
+ * key_revoke - Revoke a key.
+ * @key: The key to be revoked.
+ *
+ * Mark a key as being revoked and ask the type to free up its resources.  The
+ * revocation timeout is set and the key and all its links will be
+ * automatically garbage collected after key_gc_delay amount of time if they
+ * are not manually dealt with first.
+ */
+void key_revoke(struct key *key)
+{
+	time64_t time;
+
+	key_check(key);
+
+	/* make sure no one's trying to change or use the key when we mark it
+	 * - we tell lockdep that we might nest because we might be revoking an
+	 *   authorisation key whilst holding the sem on a key we've just
+	 *   instantiated
+	 */
+	down_write_nested(&key->sem, 1);
+	if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags)) {
+		notify_key(key, NOTIFY_KEY_REVOKED, 0);
+		if (key->type->revoke)
+			key->type->revoke(key);
+
+		/* set the death time to no more than the expiry time */
+		time = ktime_get_real_seconds();
+		if (key->revoked_at == 0 || key->revoked_at > time) {
+			key->revoked_at = time;
+			key_schedule_gc(key->revoked_at + key_gc_delay);
+		}
+	}
+
+	up_write(&key->sem);
+}
+EXPORT_SYMBOL(key_revoke);
+
+/**
+ * key_invalidate - Invalidate a key.
+ * @key: The key to be invalidated.
+ *
+ * Mark a key as being invalidated and have it cleaned up immediately.  The key
+ * is ignored by all searches and other operations from this point.
+ */
+void key_invalidate(struct key *key)
+{
+	kenter("%d", key_serial(key));
+
+	key_check(key);
+
+	if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
+		down_write_nested(&key->sem, 1);
+		if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
+			notify_key(key, NOTIFY_KEY_INVALIDATED, 0);
+			key_schedule_gc_links();
+		}
+		up_write(&key->sem);
+	}
+}
+EXPORT_SYMBOL(key_invalidate);
+
+/**
+ * generic_key_instantiate - Simple instantiation of a key from preparsed data
+ * @key: The key to be instantiated
+ * @prep: The preparsed data to load.
+ *
+ * Instantiate a key from preparsed data.  We assume we can just copy the data
+ * in directly and clear the old pointers.
+ *
+ * This can be pointed to directly by the key type instantiate op pointer.
+ */
+int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
+{
+	int ret;
+
+	pr_devel("==>%s()\n", __func__);
+
+	ret = key_payload_reserve(key, prep->quotalen);
+	if (ret == 0) {
+		rcu_assign_keypointer(key, prep->payload.data[0]);
+		key->payload.data[1] = prep->payload.data[1];
+		key->payload.data[2] = prep->payload.data[2];
+		key->payload.data[3] = prep->payload.data[3];
+		prep->payload.data[0] = NULL;
+		prep->payload.data[1] = NULL;
+		prep->payload.data[2] = NULL;
+		prep->payload.data[3] = NULL;
+	}
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+}
+EXPORT_SYMBOL(generic_key_instantiate);
+
+/**
+ * register_key_type - Register a type of key.
+ * @ktype: The new key type.
+ *
+ * Register a new key type.
+ *
+ * Returns 0 on success or -EEXIST if a type of this name already exists.
+ */
+int register_key_type(struct key_type *ktype)
+{
+	struct key_type *p;
+	int ret;
+
+	memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
+
+	ret = -EEXIST;
+	down_write(&key_types_sem);
+
+	/* disallow key types with the same name */
+	list_for_each_entry(p, &key_types_list, link) {
+		if (strcmp(p->name, ktype->name) == 0)
+			goto out;
+	}
+
+	/* store the type */
+	list_add(&ktype->link, &key_types_list);
+
+	pr_notice("Key type %s registered\n", ktype->name);
+	ret = 0;
+
+out:
+	up_write(&key_types_sem);
+	return ret;
+}
+EXPORT_SYMBOL(register_key_type);
+
+/**
+ * unregister_key_type - Unregister a type of key.
+ * @ktype: The key type.
+ *
+ * Unregister a key type and mark all the extant keys of this type as dead.
+ * Those keys of this type are then destroyed to get rid of their payloads and
+ * they and their links will be garbage collected as soon as possible.
+ */
+void unregister_key_type(struct key_type *ktype)
+{
+	down_write(&key_types_sem);
+	list_del_init(&ktype->link);
+	downgrade_write(&key_types_sem);
+	key_gc_keytype(ktype);
+	pr_notice("Key type %s unregistered\n", ktype->name);
+	up_read(&key_types_sem);
+}
+EXPORT_SYMBOL(unregister_key_type);
+
+/*
+ * Initialise the key management state.
+ */
+void __init key_init(void)
+{
+	/* allocate a slab in which we can store keys */
+	key_jar = kmem_cache_create("key_jar", sizeof(struct key),
+			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
+
+	/* add the special key types */
+	list_add_tail(&key_type_keyring.link, &key_types_list);
+	list_add_tail(&key_type_dead.link, &key_types_list);
+	list_add_tail(&key_type_user.link, &key_types_list);
+	list_add_tail(&key_type_logon.link, &key_types_list);
+
+	/* record the root user tracking */
+	rb_link_node(&root_key_user.node,
+		     NULL,
+		     &key_user_tree.rb_node);
+
+	rb_insert_color(&root_key_user.node,
+			&key_user_tree);
+}