v4.19.13 snapshot.
diff --git a/security/keys/key.c b/security/keys/key.c
new file mode 100644
index 0000000..d97c939
--- /dev/null
+++ b/security/keys/key.c
@@ -0,0 +1,1181 @@
+/* Basic authentication token and access key management
+ *
+ * Copyright (C) 2004-2008 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 License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.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/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;
+
+ refcount_set(&key->usage, 1);
+ init_rwsem(&key->sem);
+ lockdep_set_class(&key->sem, &type->lock_class);
+ key->index_key.type = type;
+ key->user = user;
+ key->quotalen = quotalen;
+ key->datalen = type->def_datalen;
+ key->uid = uid;
+ key->gid = gid;
+ key->perm = perm;
+ key->restrict_link = restrict_link;
+
+ 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;
+
+#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 */
+ 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);
+
+ 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(key, _edit);
+ }
+
+ /* disable the authorisation key */
+ if (authkey)
+ key_revoke(authkey);
+
+ if (prep->expiry != TIME64_MAX) {
+ key->expiry = prep->expiry;
+ key_schedule_gc(prep->expiry + key_gc_delay);
+ }
+ }
+ }
+
+ 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;
+ int ret;
+
+ memset(&prep, 0, sizeof(prep));
+ 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_begin(keyring, &key->index_key, &edit);
+ if (ret < 0)
+ goto error;
+
+ 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;
+ 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_begin(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);
+ key->expiry = ktime_get_real_seconds() + timeout;
+ key_schedule_gc(key->expiry + key_gc_delay);
+
+ 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(key, &edit);
+
+ /* disable the authorisation key */
+ if (authkey)
+ key_revoke(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 = 0;
+
+ /* make the changes with the locks held to prevent races */
+ down_write(&key->sem);
+
+ if (timeout > 0)
+ expiry = ktime_get_real_seconds() + timeout;
+
+ key->expiry = expiry;
+ key_schedule_gc(key->expiry + key_gc_delay);
+
+ 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);
+
+ 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;
+ 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.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);
+
+ ret = __key_link_begin(keyring, &index_key, &edit);
+ if (ret < 0) {
+ key_ref = ERR_PTR(ret);
+ goto error_free_prep;
+ }
+
+ 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;
+ }
+
+ 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);
+ 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);
+
+ 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) &&
+ 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))
+ 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);
+}