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afs: Provide an RCU-capable key lookup 

Provide an RCU-capable key lookup function.  We don't want to call
afs_request_key() in RCU-mode pathwalk as request_key() might sleep, even if
we don't ask it to construct anything as it might find a key that is currently
undergoing construction.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2019-05-20 08:48:46 +01:00
parent 23a289137a
commit 8b6a666a97
3 changed files with 45 additions and 3 deletions
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1
fs/afs/internal.h
View File

@ -1217,6 +1217,7 @@ extern void afs_cache_permit(struct afs_vnode *, struct key *, unsigned int,
struct afs_status_cb *);
extern void afs_zap_permits(struct rcu_head *);
extern struct key *afs_request_key(struct afs_cell *);
extern struct key *afs_request_key_rcu(struct afs_cell *);
extern int afs_check_permit(struct afs_vnode *, struct key *, afs_access_t *);
extern int afs_permission(struct inode *, int);
extern void __exit afs_clean_up_permit_cache(void);

33
fs/afs/security.c
View File

@ -27,8 +27,37 @@ struct key *afs_request_key(struct afs_cell *cell)
_enter("{%x}", key_serial(cell->anonymous_key));
_debug("key %s", cell->anonymous_key->description);
key = request_key(&key_type_rxrpc, cell->anonymous_key->description,
NULL);
key = request_key_net(&key_type_rxrpc, cell->anonymous_key->description,
cell->net->net, NULL);
if (IS_ERR(key)) {
if (PTR_ERR(key) != -ENOKEY) {
_leave(" = %ld", PTR_ERR(key));
return key;
}
/* act as anonymous user */
_leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
return key_get(cell->anonymous_key);
} else {
/* act as authorised user */
_leave(" = {%x} [auth]", key_serial(key));
return key;
}
}
/*
* Get a key when pathwalk is in rcuwalk mode.
*/
struct key *afs_request_key_rcu(struct afs_cell *cell)
{
struct key *key;
_enter("{%x}", key_serial(cell->anonymous_key));
_debug("key %s", cell->anonymous_key->description);
key = request_key_net_rcu(&key_type_rxrpc,
cell->anonymous_key->description,
cell->net->net);
if (IS_ERR(key)) {
if (PTR_ERR(key) != -ENOKEY) {
_leave(" = %ld", PTR_ERR(key));

14
include/linux/key.h
View File

@ -324,7 +324,7 @@ static inline struct key *request_key(struct key_type *type,
}
#ifdef CONFIG_NET
/*
/**
* request_key_net - Request a key for a net namespace and wait for construction
* @type: Type of key.
* @description: The searchable description of the key.
@ -341,6 +341,18 @@ static inline struct key *request_key(struct key_type *type,
*/
#define request_key_net(type, description, net, callout_info) \
request_key_tag(type, description, net->key_domain, callout_info);
/**
* request_key_net_rcu - Request a key for a net namespace under RCU conditions
* @type: Type of key.
* @description: The searchable description of the key.
* @net: The network namespace that is the key's domain of operation.
*
* As for request_key_rcu() except that only keys that operate the specified
* network namespace are used.
*/
#define request_key_net_rcu(type, description, net) \
request_key_rcu(type, description, net->key_domain);
#endif /* CONFIG_NET */
extern int wait_for_key_construction(struct key *key, bool intr);