net/sunrpc/auth.c

   1 /*
   2  * linux/net/sunrpc/auth.c
   3  *
   4  * Generic RPC client authentication API.
   5  *
   6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/sched.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/errno.h>
  14 #include <linux/sunrpc/clnt.h>
  15 #include <linux/spinlock.h>
  16
  17 #ifdef RPC_DEBUG
  18 # define RPCDBG_FACILITY        RPCDBG_AUTH
  19 #endif
  20
  21 static DEFINE_SPINLOCK(rpc_authflavor_lock);
  22 static const struct rpc_authops *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
  23         &authnull_ops,          /* AUTH_NULL */
  24         &authunix_ops,          /* AUTH_UNIX */
  25         NULL,                   /* others can be loadable modules */
  26 };
  27
  28 static LIST_HEAD(cred_unused);
  29 static unsigned long number_cred_unused;
  30
  31 static u32
  32 pseudoflavor_to_flavor(u32 flavor) {
  33         if (flavor >= RPC_AUTH_MAXFLAVOR)
  34                 return RPC_AUTH_GSS;
  35         return flavor;
  36 }
  37
  38 int
  39 rpcauth_register(const struct rpc_authops *ops)
  40 {
  41         rpc_authflavor_t flavor;
  42         int ret = -EPERM;
  43
  44         if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
  45                 return -EINVAL;
  46         spin_lock(&rpc_authflavor_lock);
  47         if (auth_flavors[flavor] == NULL) {
  48                 auth_flavors[flavor] = ops;
  49                 ret = 0;
  50         }
  51         spin_unlock(&rpc_authflavor_lock);
  52         return ret;
  53 }
  54
  55 int
  56 rpcauth_unregister(const struct rpc_authops *ops)
  57 {
  58         rpc_authflavor_t flavor;
  59         int ret = -EPERM;
  60
  61         if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
  62                 return -EINVAL;
  63         spin_lock(&rpc_authflavor_lock);
  64         if (auth_flavors[flavor] == ops) {
  65                 auth_flavors[flavor] = NULL;
  66                 ret = 0;
  67         }
  68         spin_unlock(&rpc_authflavor_lock);
  69         return ret;
  70 }
  71
  72 struct rpc_auth *
  73 rpcauth_create(rpc_authflavor_t pseudoflavor, struct rpc_clnt *clnt)
  74 {
  75         struct rpc_auth         *auth;
  76         const struct rpc_authops *ops;
  77         u32                     flavor = pseudoflavor_to_flavor(pseudoflavor);
  78
  79         auth = ERR_PTR(-EINVAL);
  80         if (flavor >= RPC_AUTH_MAXFLAVOR)
  81                 goto out;
  82
  83 #ifdef CONFIG_KMOD
  84         if ((ops = auth_flavors[flavor]) == NULL)
  85                 request_module("rpc-auth-%u", flavor);
  86 #endif
  87         spin_lock(&rpc_authflavor_lock);
  88         ops = auth_flavors[flavor];
  89         if (ops == NULL || !try_module_get(ops->owner)) {
  90                 spin_unlock(&rpc_authflavor_lock);
  91                 goto out;
  92         }
  93         spin_unlock(&rpc_authflavor_lock);
  94         auth = ops->create(clnt, pseudoflavor);
  95         module_put(ops->owner);
  96         if (IS_ERR(auth))
  97                 return auth;
  98         if (clnt->cl_auth)
  99                 rpcauth_release(clnt->cl_auth);
 100         clnt->cl_auth = auth;
 101
 102 out:
 103         return auth;
 104 }
 105
 106 void
 107 rpcauth_release(struct rpc_auth *auth)
 108 {
 109         if (!atomic_dec_and_test(&auth->au_count))
 110                 return;
 111         auth->au_ops->destroy(auth);
 112 }
 113
 114 static DEFINE_SPINLOCK(rpc_credcache_lock);
 115
 116 static void
 117 rpcauth_unhash_cred_locked(struct rpc_cred *cred)
 118 {
 119         hlist_del_rcu(&cred->cr_hash);
 120         smp_mb__before_clear_bit();
 121         clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
 122 }
 123
 124 static void
 125 rpcauth_unhash_cred(struct rpc_cred *cred)
 126 {
 127         spinlock_t *cache_lock;
 128
 129         cache_lock = &cred->cr_auth->au_credcache->lock;
 130         spin_lock(cache_lock);
 131         if (atomic_read(&cred->cr_count) == 0)
 132                 rpcauth_unhash_cred_locked(cred);
 133         spin_unlock(cache_lock);
 134 }
 135
 136 /*
 137  * Initialize RPC credential cache
 138  */
 139 int
 140 rpcauth_init_credcache(struct rpc_auth *auth)
 141 {
 142         struct rpc_cred_cache *new;
 143         int i;
 144
 145         new = kmalloc(sizeof(*new), GFP_KERNEL);
 146         if (!new)
 147                 return -ENOMEM;
 148         for (i = 0; i < RPC_CREDCACHE_NR; i++)
 149                 INIT_HLIST_HEAD(&new->hashtable[i]);
 150         spin_lock_init(&new->lock);
 151         auth->au_credcache = new;
 152         return 0;
 153 }
 154
 155 /*
 156  * Destroy a list of credentials
 157  */
 158 static inline
 159 void rpcauth_destroy_credlist(struct list_head *head)
 160 {
 161         struct rpc_cred *cred;
 162
 163         while (!list_empty(head)) {
 164                 cred = list_entry(head->next, struct rpc_cred, cr_lru);
 165                 list_del_init(&cred->cr_lru);
 166                 put_rpccred(cred);
 167         }
 168 }
 169
 170 /*
 171  * Clear the RPC credential cache, and delete those credentials
 172  * that are not referenced.
 173  */
 174 void
 175 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
 176 {
 177         LIST_HEAD(free);
 178         struct hlist_head *head;
 179         struct rpc_cred *cred;
 180         int             i;
 181
 182         spin_lock(&rpc_credcache_lock);
 183         spin_lock(&cache->lock);
 184         for (i = 0; i < RPC_CREDCACHE_NR; i++) {
 185                 head = &cache->hashtable[i];
 186                 while (!hlist_empty(head)) {
 187                         cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
 188                         get_rpccred(cred);
 189                         if (!list_empty(&cred->cr_lru)) {
 190                                 list_del(&cred->cr_lru);
 191                                 number_cred_unused--;
 192                         }
 193                         list_add_tail(&cred->cr_lru, &free);
 194                         rpcauth_unhash_cred_locked(cred);
 195                 }
 196         }
 197         spin_unlock(&cache->lock);
 198         spin_unlock(&rpc_credcache_lock);
 199         rpcauth_destroy_credlist(&free);
 200 }
 201
 202 /*
 203  * Destroy the RPC credential cache
 204  */
 205 void
 206 rpcauth_destroy_credcache(struct rpc_auth *auth)
 207 {
 208         struct rpc_cred_cache *cache = auth->au_credcache;
 209
 210         if (cache) {
 211                 auth->au_credcache = NULL;
 212                 rpcauth_clear_credcache(cache);
 213                 kfree(cache);
 214         }
 215 }
 216
 217 /*
 218  * Remove stale credentials. Avoid sleeping inside the loop.
 219  */
 220 static int
 221 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
 222 {
 223         spinlock_t *cache_lock;
 224         struct rpc_cred *cred;
 225
 226         while (!list_empty(&cred_unused)) {
 227                 cred = list_entry(cred_unused.next, struct rpc_cred, cr_lru);
 228                 list_del_init(&cred->cr_lru);
 229                 number_cred_unused--;
 230                 if (atomic_read(&cred->cr_count) != 0)
 231                         continue;
 232                 cache_lock = &cred->cr_auth->au_credcache->lock;
 233                 spin_lock(cache_lock);
 234                 if (atomic_read(&cred->cr_count) == 0) {
 235                         get_rpccred(cred);
 236                         list_add_tail(&cred->cr_lru, free);
 237                         rpcauth_unhash_cred_locked(cred);
 238                         nr_to_scan--;
 239                 }
 240                 spin_unlock(cache_lock);
 241                 if (nr_to_scan == 0)
 242                         break;
 243         }
 244         return nr_to_scan;
 245 }
 246
 247 /*
 248  * Run memory cache shrinker.
 249  */
 250 static int
 251 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
 252 {
 253         LIST_HEAD(free);
 254         int res;
 255
 256         if (list_empty(&cred_unused))
 257                 return 0;
 258         spin_lock(&rpc_credcache_lock);
 259         nr_to_scan = rpcauth_prune_expired(&free, nr_to_scan);
 260         res = (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
 261         spin_unlock(&rpc_credcache_lock);
 262         rpcauth_destroy_credlist(&free);
 263         return res;
 264 }
 265
 266 /*
 267  * Look up a process' credentials in the authentication cache
 268  */
 269 struct rpc_cred *
 270 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
 271                 int flags)
 272 {
 273         LIST_HEAD(free);
 274         struct rpc_cred_cache *cache = auth->au_credcache;
 275         struct hlist_node *pos;
 276         struct rpc_cred *cred = NULL,
 277                         *entry, *new;
 278         int             nr = 0;
 279
 280         if (!(flags & RPCAUTH_LOOKUP_ROOTCREDS))
 281                 nr = acred->uid & RPC_CREDCACHE_MASK;
 282
 283         rcu_read_lock();
 284         hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
 285                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 286                         continue;
 287                 spin_lock(&cache->lock);
 288                 if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
 289                         spin_unlock(&cache->lock);
 290                         continue;
 291                 }
 292                 cred = get_rpccred(entry);
 293                 spin_unlock(&cache->lock);
 294                 break;
 295         }
 296         rcu_read_unlock();
 297
 298         if (cred != NULL)
 299                 goto found;
 300
 301         new = auth->au_ops->crcreate(auth, acred, flags);
 302         if (IS_ERR(new)) {
 303                 cred = new;
 304                 goto out;
 305         }
 306
 307         spin_lock(&cache->lock);
 308         hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
 309                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 310                         continue;
 311                 cred = get_rpccred(entry);
 312                 break;
 313         }
 314         if (cred == NULL) {
 315                 cred = new;
 316                 set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
 317                 hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
 318         } else
 319                 list_add_tail(&new->cr_lru, &free);
 320         spin_unlock(&cache->lock);
 321 found:
 322         if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags)
 323                         && cred->cr_ops->cr_init != NULL
 324                         && !(flags & RPCAUTH_LOOKUP_NEW)) {
 325                 int res = cred->cr_ops->cr_init(auth, cred);
 326                 if (res < 0) {
 327                         put_rpccred(cred);
 328                         cred = ERR_PTR(res);
 329                 }
 330         }
 331         rpcauth_destroy_credlist(&free);
 332 out:
 333         return cred;
 334 }
 335
 336 struct rpc_cred *
 337 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
 338 {
 339         struct auth_cred acred = {
 340                 .uid = current->fsuid,
 341                 .gid = current->fsgid,
 342                 .group_info = current->group_info,
 343         };
 344         struct rpc_cred *ret;
 345
 346         dprintk("RPC:       looking up %s cred\n",
 347                 auth->au_ops->au_name);
 348         get_group_info(acred.group_info);
 349         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
 350         put_group_info(acred.group_info);
 351         return ret;
 352 }
 353
 354 void
 355 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
 356                   struct rpc_auth *auth, const struct rpc_credops *ops)
 357 {
 358         INIT_HLIST_NODE(&cred->cr_hash);
 359         INIT_LIST_HEAD(&cred->cr_lru);
 360         atomic_set(&cred->cr_count, 1);
 361         cred->cr_auth = auth;
 362         cred->cr_ops = ops;
 363         cred->cr_expire = jiffies;
 364 #ifdef RPC_DEBUG
 365         cred->cr_magic = RPCAUTH_CRED_MAGIC;
 366 #endif
 367         cred->cr_uid = acred->uid;
 368 }
 369 EXPORT_SYMBOL(rpcauth_init_cred);
 370
 371 struct rpc_cred *
 372 rpcauth_bindcred(struct rpc_task *task)
 373 {
 374         struct rpc_auth *auth = task->tk_client->cl_auth;
 375         struct auth_cred acred = {
 376                 .uid = current->fsuid,
 377                 .gid = current->fsgid,
 378                 .group_info = current->group_info,
 379         };
 380         struct rpc_cred *ret;
 381         int flags = 0;
 382
 383         dprintk("RPC: %5u looking up %s cred\n",
 384                 task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
 385         get_group_info(acred.group_info);
 386         if (task->tk_flags & RPC_TASK_ROOTCREDS)
 387                 flags |= RPCAUTH_LOOKUP_ROOTCREDS;
 388         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
 389         if (!IS_ERR(ret))
 390                 task->tk_msg.rpc_cred = ret;
 391         else
 392                 task->tk_status = PTR_ERR(ret);
 393         put_group_info(acred.group_info);
 394         return ret;
 395 }
 396
 397 void
 398 rpcauth_holdcred(struct rpc_task *task)
 399 {
 400         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 401         if (cred != NULL) {
 402                 get_rpccred(cred);
 403                 dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
 404                                 cred->cr_auth->au_ops->au_name, cred);
 405         }
 406 }
 407
 408 void
 409 put_rpccred(struct rpc_cred *cred)
 410 {
 411         /* Fast path for unhashed credentials */
 412         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
 413                 goto need_lock;
 414
 415         if (!atomic_dec_and_test(&cred->cr_count))
 416                 return;
 417         goto out_destroy;
 418 need_lock:
 419         if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
 420                 return;
 421         if (!list_empty(&cred->cr_lru)) {
 422                 number_cred_unused--;
 423                 list_del_init(&cred->cr_lru);
 424         }
 425         if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
 426                 rpcauth_unhash_cred(cred);
 427         else if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
 428                 cred->cr_expire = jiffies;
 429                 list_add_tail(&cred->cr_lru, &cred_unused);
 430                 number_cred_unused++;
 431                 spin_unlock(&rpc_credcache_lock);
 432                 return;
 433         }
 434         spin_unlock(&rpc_credcache_lock);
 435 out_destroy:
 436         cred->cr_ops->crdestroy(cred);
 437 }
 438
 439 void
 440 rpcauth_unbindcred(struct rpc_task *task)
 441 {
 442         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 443
 444         dprintk("RPC: %5u releasing %s cred %p\n",
 445                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 446
 447         put_rpccred(cred);
 448         task->tk_msg.rpc_cred = NULL;
 449 }
 450
 451 __be32 *
 452 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
 453 {
 454         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 455
 456         dprintk("RPC: %5u marshaling %s cred %p\n",
 457                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 458
 459         return cred->cr_ops->crmarshal(task, p);
 460 }
 461
 462 __be32 *
 463 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
 464 {
 465         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 466
 467         dprintk("RPC: %5u validating %s cred %p\n",
 468                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 469
 470         return cred->cr_ops->crvalidate(task, p);
 471 }
 472
 473 int
 474 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
 475                 __be32 *data, void *obj)
 476 {
 477         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 478
 479         dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
 480                         task->tk_pid, cred->cr_ops->cr_name, cred);
 481         if (cred->cr_ops->crwrap_req)
 482                 return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
 483         /* By default, we encode the arguments normally. */
 484         return rpc_call_xdrproc(encode, rqstp, data, obj);
 485 }
 486
 487 int
 488 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
 489                 __be32 *data, void *obj)
 490 {
 491         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 492
 493         dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
 494                         task->tk_pid, cred->cr_ops->cr_name, cred);
 495         if (cred->cr_ops->crunwrap_resp)
 496                 return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
 497                                                    data, obj);
 498         /* By default, we decode the arguments normally. */
 499         return rpc_call_xdrproc(decode, rqstp, data, obj);
 500 }
 501
 502 int
 503 rpcauth_refreshcred(struct rpc_task *task)
 504 {
 505         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 506         int err;
 507
 508         dprintk("RPC: %5u refreshing %s cred %p\n",
 509                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 510
 511         err = cred->cr_ops->crrefresh(task);
 512         if (err < 0)
 513                 task->tk_status = err;
 514         return err;
 515 }
 516
 517 void
 518 rpcauth_invalcred(struct rpc_task *task)
 519 {
 520         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 521
 522         dprintk("RPC: %5u invalidating %s cred %p\n",
 523                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 524         if (cred)
 525                 clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
 526 }
 527
 528 int
 529 rpcauth_uptodatecred(struct rpc_task *task)
 530 {
 531         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 532
 533         return cred == NULL ||
 534                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
 535 }
 536
 537 static struct shrinker rpc_cred_shrinker = {
 538         .shrink = rpcauth_cache_shrinker,
 539         .seeks = DEFAULT_SEEKS,
 540 };
 541
 542 void __init rpcauth_init_module(void)
 543 {
 544         rpc_init_authunix();
 545         register_shrinker(&rpc_cred_shrinker);
 546 }
 547
 548 void __exit rpcauth_remove_module(void)
 549 {
 550         unregister_shrinker(&rpc_cred_shrinker);
 551 }