/* 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 #include #include #include #include #include #include #include #include #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 = NULL; struct rb_node **p; try_again: 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 */ atomic_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: atomic_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 (atomic_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(
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>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) __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 (atomic_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: /* pretend it doesn't exist if it is awaiting deletion */ if (atomic_read(&key->usage) == 0) goto not_found; /* this races with key_put(), but that doesn't matter since key_put() * doesn't actually change the key */ __key_get(key); 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) { struct timespec now; time_t expiry = 0; /* make the changes with the locks held to prevent races */ down_write(&key->sem); if (timeout > 0) { now = current_kernel_time(); expiry = now.tv_sec + 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 instantiates it */ clear_bit(KEY_FLAG_NEGATIVE, &key->flags); 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; /* 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); 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.trusted = flags & KEY_ALLOC_TRUSTED; prep.expiry = TIME_T_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_ref = ERR_PTR(-EPERM); if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags)) goto error_free_prep; flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0; ret = __key_link_begin(keyring, &index_key, &edit); if (ret < 0) { key_ref = ERR_PTR(ret); goto error_free_prep; } /* 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); 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_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) goto error; /* attempt to update it if supported */ ret = -EOPNOTSUPP; if (!key->type->update) goto error; memset(&prep, 0, sizeof(prep)); prep.data = payload; prep.datalen = plen; prep.quotalen = key->type->def_datalen; prep.expiry = TIME_T_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 instantiates it */ clear_bit(KEY_FLAG_NEGATIVE, &key->flags); 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) { struct timespec now; time_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 */ now = current_kernel_time(); time = now.tv_sec; 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); }