linux/net/sunrpc/svcauth.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * linux/net/sunrpc/svcauth.c
   4 *
   5 * The generic interface for RPC authentication on the server side.
   6 *
   7 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   8 *
   9 * CHANGES
  10 * 19-Apr-2000 Chris Evans      - Security fix
  11 */
  12
  13#include <linux/types.h>
  14#include <linux/module.h>
  15#include <linux/sunrpc/types.h>
  16#include <linux/sunrpc/xdr.h>
  17#include <linux/sunrpc/svcsock.h>
  18#include <linux/sunrpc/svcauth.h>
  19#include <linux/err.h>
  20#include <linux/hash.h>
  21
  22#include <trace/events/sunrpc.h>
  23
  24#include "sunrpc.h"
  25
  26#define RPCDBG_FACILITY RPCDBG_AUTH
  27
  28
  29/*
  30 * Table of authenticators
  31 */
  32extern struct auth_ops svcauth_null;
  33extern struct auth_ops svcauth_unix;
  34
  35static struct auth_ops __rcu *authtab[RPC_AUTH_MAXFLAVOR] = {
  36        [RPC_AUTH_NULL] = (struct auth_ops __force __rcu *)&svcauth_null,
  37        [RPC_AUTH_UNIX] = (struct auth_ops __force __rcu *)&svcauth_unix,
  38};
  39
  40static struct auth_ops *
  41svc_get_auth_ops(rpc_authflavor_t flavor)
  42{
  43        struct auth_ops         *aops;
  44
  45        if (flavor >= RPC_AUTH_MAXFLAVOR)
  46                return NULL;
  47        rcu_read_lock();
  48        aops = rcu_dereference(authtab[flavor]);
  49        if (aops != NULL && !try_module_get(aops->owner))
  50                aops = NULL;
  51        rcu_read_unlock();
  52        return aops;
  53}
  54
  55static void
  56svc_put_auth_ops(struct auth_ops *aops)
  57{
  58        module_put(aops->owner);
  59}
  60
  61int
  62svc_authenticate(struct svc_rqst *rqstp, __be32 *authp)
  63{
  64        rpc_authflavor_t        flavor;
  65        struct auth_ops         *aops;
  66
  67        *authp = rpc_auth_ok;
  68
  69        flavor = svc_getnl(&rqstp->rq_arg.head[0]);
  70
  71        dprintk("svc: svc_authenticate (%d)\n", flavor);
  72
  73        aops = svc_get_auth_ops(flavor);
  74        if (aops == NULL) {
  75                *authp = rpc_autherr_badcred;
  76                return SVC_DENIED;
  77        }
  78
  79        rqstp->rq_auth_slack = 0;
  80        init_svc_cred(&rqstp->rq_cred);
  81
  82        rqstp->rq_authop = aops;
  83        return aops->accept(rqstp, authp);
  84}
  85EXPORT_SYMBOL_GPL(svc_authenticate);
  86
  87int svc_set_client(struct svc_rqst *rqstp)
  88{
  89        rqstp->rq_client = NULL;
  90        return rqstp->rq_authop->set_client(rqstp);
  91}
  92EXPORT_SYMBOL_GPL(svc_set_client);
  93
  94/* A request, which was authenticated, has now executed.
  95 * Time to finalise the credentials and verifier
  96 * and release and resources
  97 */
  98int svc_authorise(struct svc_rqst *rqstp)
  99{
 100        struct auth_ops *aops = rqstp->rq_authop;
 101        int rv = 0;
 102
 103        rqstp->rq_authop = NULL;
 104
 105        if (aops) {
 106                rv = aops->release(rqstp);
 107                svc_put_auth_ops(aops);
 108        }
 109        return rv;
 110}
 111
 112int
 113svc_auth_register(rpc_authflavor_t flavor, struct auth_ops *aops)
 114{
 115        struct auth_ops *old;
 116        int rv = -EINVAL;
 117
 118        if (flavor < RPC_AUTH_MAXFLAVOR) {
 119                old = cmpxchg((struct auth_ops ** __force)&authtab[flavor], NULL, aops);
 120                if (old == NULL || old == aops)
 121                        rv = 0;
 122        }
 123        return rv;
 124}
 125EXPORT_SYMBOL_GPL(svc_auth_register);
 126
 127void
 128svc_auth_unregister(rpc_authflavor_t flavor)
 129{
 130        if (flavor < RPC_AUTH_MAXFLAVOR)
 131                rcu_assign_pointer(authtab[flavor], NULL);
 132}
 133EXPORT_SYMBOL_GPL(svc_auth_unregister);
 134
 135/**************************************************
 136 * 'auth_domains' are stored in a hash table indexed by name.
 137 * When the last reference to an 'auth_domain' is dropped,
 138 * the object is unhashed and freed.
 139 * If auth_domain_lookup fails to find an entry, it will return
 140 * it's second argument 'new'.  If this is non-null, it will
 141 * have been atomically linked into the table.
 142 */
 143
 144#define DN_HASHBITS     6
 145#define DN_HASHMAX      (1<<DN_HASHBITS)
 146
 147static struct hlist_head        auth_domain_table[DN_HASHMAX];
 148static DEFINE_SPINLOCK(auth_domain_lock);
 149
 150static void auth_domain_release(struct kref *kref)
 151        __releases(&auth_domain_lock)
 152{
 153        struct auth_domain *dom = container_of(kref, struct auth_domain, ref);
 154
 155        hlist_del_rcu(&dom->hash);
 156        dom->flavour->domain_release(dom);
 157        spin_unlock(&auth_domain_lock);
 158}
 159
 160void auth_domain_put(struct auth_domain *dom)
 161{
 162        kref_put_lock(&dom->ref, auth_domain_release, &auth_domain_lock);
 163}
 164EXPORT_SYMBOL_GPL(auth_domain_put);
 165
 166struct auth_domain *
 167auth_domain_lookup(char *name, struct auth_domain *new)
 168{
 169        struct auth_domain *hp;
 170        struct hlist_head *head;
 171
 172        head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
 173
 174        spin_lock(&auth_domain_lock);
 175
 176        hlist_for_each_entry(hp, head, hash) {
 177                if (strcmp(hp->name, name)==0) {
 178                        kref_get(&hp->ref);
 179                        spin_unlock(&auth_domain_lock);
 180                        return hp;
 181                }
 182        }
 183        if (new)
 184                hlist_add_head_rcu(&new->hash, head);
 185        spin_unlock(&auth_domain_lock);
 186        return new;
 187}
 188EXPORT_SYMBOL_GPL(auth_domain_lookup);
 189
 190struct auth_domain *auth_domain_find(char *name)
 191{
 192        struct auth_domain *hp;
 193        struct hlist_head *head;
 194
 195        head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
 196
 197        rcu_read_lock();
 198        hlist_for_each_entry_rcu(hp, head, hash) {
 199                if (strcmp(hp->name, name)==0) {
 200                        if (!kref_get_unless_zero(&hp->ref))
 201                                hp = NULL;
 202                        rcu_read_unlock();
 203                        return hp;
 204                }
 205        }
 206        rcu_read_unlock();
 207        return NULL;
 208}
 209EXPORT_SYMBOL_GPL(auth_domain_find);
 210
 211/**
 212 * auth_domain_cleanup - check that the auth_domain table is empty
 213 *
 214 * On module unload the auth_domain_table must be empty.  To make it
 215 * easier to catch bugs which don't clean up domains properly, we
 216 * warn if anything remains in the table at cleanup time.
 217 *
 218 * Note that we cannot proactively remove the domains at this stage.
 219 * The ->release() function might be in a module that has already been
 220 * unloaded.
 221 */
 222
 223void auth_domain_cleanup(void)
 224{
 225        int h;
 226        struct auth_domain *hp;
 227
 228        for (h = 0; h < DN_HASHMAX; h++)
 229                hlist_for_each_entry(hp, &auth_domain_table[h], hash)
 230                        pr_warn("svc: domain %s still present at module unload.\n",
 231                                hp->name);
 232}
 233