/* 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 <linux/user_namespace.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 = 200;	/* root's key count quota */unsigned int key_quota_root_maxbytes = 20000;	/* 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_DEBUGGINGvoid __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(uid_t uid, struct user_namespace *user_ns){	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 < user->uid)			p = &(*p)->rb_left;		else if (uid > user->uid)			p = &(*p)->rb_right;		else if (user_ns < user->user_ns)			p = &(*p)->rb_left;		else if (user_ns > user->user_ns)			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->user_ns = get_user_ns(user_ns);	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);		put_user_ns(user->user_ns); 		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. * * 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 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,		      uid_t uid, gid_t gid, const struct cred *cred,		      key_perm_t perm, unsigned long flags){	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) + 1;	quotalen = desclen + type->def_datalen; 	/* get hold of the key tracking for this user */	user = key_user_lookup(uid, cred->user_ns);	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 == 0) ?			key_quota_root_maxkeys : key_quota_maxkeys;		unsigned maxbytes = (uid == 0) ?			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_alloc(key_jar, GFP_KERNEL);	if (!key)		goto no_memory_2; 	if (desc) {		key->description = kmemdup(desc, desclen, GFP_KERNEL);		if (!key->description)			goto no_memory_3;	} 	atomic_set(&key->usage, 1);	init_rwsem(&key->sem);	lockdep_set_class(&key->sem, &type->lock_class);	key->type = type;	key->user = user;	key->quotalen = quotalen;	key->datalen = type->def_datalen;	key->uid = uid;	key->gid = gid;	key->perm = perm;	key->flags = 0;	key->expiry = 0;	key->payload.data = NULL;	key->security = NULL; 	if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))		key->flags |= 1 << KEY_FLAG_IN_QUOTA; 	memset(&key->type_data, 0, sizeof(key->type_data)); #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 = (key->user->uid == 0) ?			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); /* * 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,				      const void *data,				      size_t datalen,				      struct key *keyring,				      struct key *authkey,				      unsigned long *_prealloc){	int ret, awaken; 	key_check(key);	key_check(keyring); 	awaken = 0;	ret = -EBUSY; 	mutex_lock(&key_construction_mutex); 	/* can't instantiate twice */	if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {		/* instantiate the key */		ret = key->type->instantiate(key, data, datalen); 		if (ret == 0) {			/* mark the key as being instantiated */			atomic_inc(&key->user->nikeys);			set_bit(KEY_FLAG_INSTANTIATED, &key->flags); 			if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))				awaken = 1; 			/* and link it into the destination keyring */			if (keyring)				__key_link(keyring, key, _prealloc); 			/* disable the authorisation key */			if (authkey)				key_revoke(authkey);		}	} 	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){	unsigned long prealloc;	int ret; 	if (keyring) {		ret = __key_link_begin(keyring, key->type, key->description,				       &prealloc);		if (ret < 0)			return ret;	} 	ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey,					 &prealloc); 	if (keyring)		__key_link_end(keyring, key->type, prealloc); 

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