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linux-next/net/sunrpc/auth_null.c
NeilBrown bd95608053 sunrpc/auth: allow lockless (rcu) lookup of credential cache.
The new flag RPCAUTH_LOOKUP_RCU to credential lookup avoids locking,
does not take a reference on the returned credential, and returns
-ECHILD if a simple lookup was not possible.

The returned value can only be used within an rcu_read_lock protected
region.

The main user of this is the new rpc_lookup_cred_nonblock() which
returns a pointer to the current credential which is only rcu-safe (no
ref-count held), and might return -ECHILD if allocation was required.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-08-03 17:14:12 -04:00

145 lines
2.6 KiB
C

/*
* linux/net/sunrpc/auth_null.c
*
* AUTH_NULL authentication. Really :-)
*
* Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
*/
#include <linux/types.h>
#include <linux/module.h>
#include <linux/sunrpc/clnt.h>
#ifdef RPC_DEBUG
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
static struct rpc_auth null_auth;
static struct rpc_cred null_cred;
static struct rpc_auth *
nul_create(struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
{
atomic_inc(&null_auth.au_count);
return &null_auth;
}
static void
nul_destroy(struct rpc_auth *auth)
{
}
/*
* Lookup NULL creds for current process
*/
static struct rpc_cred *
nul_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
{
if (flags & RPCAUTH_LOOKUP_RCU)
return &null_cred;
return get_rpccred(&null_cred);
}
/*
* Destroy cred handle.
*/
static void
nul_destroy_cred(struct rpc_cred *cred)
{
}
/*
* Match cred handle against current process
*/
static int
nul_match(struct auth_cred *acred, struct rpc_cred *cred, int taskflags)
{
return 1;
}
/*
* Marshal credential.
*/
static __be32 *
nul_marshal(struct rpc_task *task, __be32 *p)
{
*p++ = htonl(RPC_AUTH_NULL);
*p++ = 0;
*p++ = htonl(RPC_AUTH_NULL);
*p++ = 0;
return p;
}
/*
* Refresh credential. This is a no-op for AUTH_NULL
*/
static int
nul_refresh(struct rpc_task *task)
{
set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
return 0;
}
static __be32 *
nul_validate(struct rpc_task *task, __be32 *p)
{
rpc_authflavor_t flavor;
u32 size;
flavor = ntohl(*p++);
if (flavor != RPC_AUTH_NULL) {
printk("RPC: bad verf flavor: %u\n", flavor);
return ERR_PTR(-EIO);
}
size = ntohl(*p++);
if (size != 0) {
printk("RPC: bad verf size: %u\n", size);
return ERR_PTR(-EIO);
}
return p;
}
const struct rpc_authops authnull_ops = {
.owner = THIS_MODULE,
.au_flavor = RPC_AUTH_NULL,
.au_name = "NULL",
.create = nul_create,
.destroy = nul_destroy,
.lookup_cred = nul_lookup_cred,
};
static
struct rpc_auth null_auth = {
.au_cslack = 4,
.au_rslack = 2,
.au_ops = &authnull_ops,
.au_flavor = RPC_AUTH_NULL,
.au_count = ATOMIC_INIT(0),
};
static
const struct rpc_credops null_credops = {
.cr_name = "AUTH_NULL",
.crdestroy = nul_destroy_cred,
.crbind = rpcauth_generic_bind_cred,
.crmatch = nul_match,
.crmarshal = nul_marshal,
.crrefresh = nul_refresh,
.crvalidate = nul_validate,
};
static
struct rpc_cred null_cred = {
.cr_lru = LIST_HEAD_INIT(null_cred.cr_lru),
.cr_auth = &null_auth,
.cr_ops = &null_credops,
.cr_count = ATOMIC_INIT(1),
.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE,
#ifdef RPC_DEBUG
.cr_magic = RPCAUTH_CRED_MAGIC,
#endif
};