linux_dsm_epyc7002/net/sunrpc/svcauth.c
Neil Brown d6740df98e [PATCH] sunrpc: fix refcounting problems in rpc servers
A recent patch fixed a problem which would occur when the refcount on an
auth_domain reached zero.  This problem has not been reported in practice
despite existing in two major kernel releases because the refcount can
never reach zero.

This patch fixes the problems that stop the refcount reaching zero.

1/ We were adding to the refcount when inserting in the hash table,
   but only removing from the hashtable when the refcount reached zero.
   Obviously it never would.  So don't count the implied reference of
   being in the hash table.

2/ There are two paths on which a socket can be destroyed.  One called
   svcauth_unix_info_release().  The other didn't.  So when the other was
   taken, we can lose a reference to an ip_map which in-turn holds a
   reference to an auth_domain

   So unify the exit paths into svc_sock_put.  This highlights the fact
   that svc_delete_socket has slightly odd semantics - it does not drop
   a reference but probably should.  Fixing this need a bit more
   thought and testing.

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-30 12:08:42 -08:00

160 lines
3.5 KiB
C

/*
* linux/net/sunrpc/svcauth.c
*
* The generic interface for RPC authentication on the server side.
*
* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
*
* CHANGES
* 19-Apr-2000 Chris Evans - Security fix
*/
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/err.h>
#include <linux/hash.h>
#define RPCDBG_FACILITY RPCDBG_AUTH
/*
* Table of authenticators
*/
extern struct auth_ops svcauth_null;
extern struct auth_ops svcauth_unix;
static DEFINE_SPINLOCK(authtab_lock);
static struct auth_ops *authtab[RPC_AUTH_MAXFLAVOR] = {
[0] = &svcauth_null,
[1] = &svcauth_unix,
};
int
svc_authenticate(struct svc_rqst *rqstp, __be32 *authp)
{
rpc_authflavor_t flavor;
struct auth_ops *aops;
*authp = rpc_auth_ok;
flavor = svc_getnl(&rqstp->rq_arg.head[0]);
dprintk("svc: svc_authenticate (%d)\n", flavor);
spin_lock(&authtab_lock);
if (flavor >= RPC_AUTH_MAXFLAVOR || !(aops = authtab[flavor])
|| !try_module_get(aops->owner)) {
spin_unlock(&authtab_lock);
*authp = rpc_autherr_badcred;
return SVC_DENIED;
}
spin_unlock(&authtab_lock);
rqstp->rq_authop = aops;
return aops->accept(rqstp, authp);
}
int svc_set_client(struct svc_rqst *rqstp)
{
return rqstp->rq_authop->set_client(rqstp);
}
/* A request, which was authenticated, has now executed.
* Time to finalise the the credentials and verifier
* and release and resources
*/
int svc_authorise(struct svc_rqst *rqstp)
{
struct auth_ops *aops = rqstp->rq_authop;
int rv = 0;
rqstp->rq_authop = NULL;
if (aops) {
rv = aops->release(rqstp);
module_put(aops->owner);
}
return rv;
}
int
svc_auth_register(rpc_authflavor_t flavor, struct auth_ops *aops)
{
int rv = -EINVAL;
spin_lock(&authtab_lock);
if (flavor < RPC_AUTH_MAXFLAVOR && authtab[flavor] == NULL) {
authtab[flavor] = aops;
rv = 0;
}
spin_unlock(&authtab_lock);
return rv;
}
void
svc_auth_unregister(rpc_authflavor_t flavor)
{
spin_lock(&authtab_lock);
if (flavor < RPC_AUTH_MAXFLAVOR)
authtab[flavor] = NULL;
spin_unlock(&authtab_lock);
}
EXPORT_SYMBOL(svc_auth_unregister);
/**************************************************
* 'auth_domains' are stored in a hash table indexed by name.
* When the last reference to an 'auth_domain' is dropped,
* the object is unhashed and freed.
* If auth_domain_lookup fails to find an entry, it will return
* it's second argument 'new'. If this is non-null, it will
* have been atomically linked into the table.
*/
#define DN_HASHBITS 6
#define DN_HASHMAX (1<<DN_HASHBITS)
#define DN_HASHMASK (DN_HASHMAX-1)
static struct hlist_head auth_domain_table[DN_HASHMAX];
static spinlock_t auth_domain_lock = SPIN_LOCK_UNLOCKED;
void auth_domain_put(struct auth_domain *dom)
{
if (atomic_dec_and_lock(&dom->ref.refcount, &auth_domain_lock)) {
hlist_del(&dom->hash);
dom->flavour->domain_release(dom);
}
}
struct auth_domain *
auth_domain_lookup(char *name, struct auth_domain *new)
{
struct auth_domain *hp;
struct hlist_head *head;
struct hlist_node *np;
head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
spin_lock(&auth_domain_lock);
hlist_for_each_entry(hp, np, head, hash) {
if (strcmp(hp->name, name)==0) {
kref_get(&hp->ref);
spin_unlock(&auth_domain_lock);
return hp;
}
}
if (new)
hlist_add_head(&new->hash, head);
spin_unlock(&auth_domain_lock);
return new;
}
struct auth_domain *auth_domain_find(char *name)
{
return auth_domain_lookup(name, NULL);
}