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/hash.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/spinlock.h>
  17
  18 #ifdef RPC_DEBUG
  19 # define RPCDBG_FACILITY        RPCDBG_AUTH
  20 #endif
  21
  22 static DEFINE_SPINLOCK(rpc_authflavor_lock);
  23 static const struct rpc_authops *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
  24         &authnull_ops,          /* AUTH_NULL */
  25         &authunix_ops,          /* AUTH_UNIX */
  26         NULL,                   /* others can be loadable modules */
  27 };
  28
  29 static LIST_HEAD(cred_unused);
  30 static unsigned long number_cred_unused;
  31
  32 static u32
  33 pseudoflavor_to_flavor(u32 flavor) {
  34         if (flavor >= RPC_AUTH_MAXFLAVOR)
  35                 return RPC_AUTH_GSS;
  36         return flavor;
  37 }
  38
  39 int
  40 rpcauth_register(const struct rpc_authops *ops)
  41 {
  42         rpc_authflavor_t flavor;
  43         int ret = -EPERM;
  44
  45         if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
  46                 return -EINVAL;
  47         spin_lock(&rpc_authflavor_lock);
  48         if (auth_flavors[flavor] == NULL) {
  49                 auth_flavors[flavor] = ops;
  50                 ret = 0;
  51         }
  52         spin_unlock(&rpc_authflavor_lock);
  53         return ret;
  54 }
  55 EXPORT_SYMBOL_GPL(rpcauth_register);
  56
  57 int
  58 rpcauth_unregister(const struct rpc_authops *ops)
  59 {
  60         rpc_authflavor_t flavor;
  61         int ret = -EPERM;
  62
  63         if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
  64                 return -EINVAL;
  65         spin_lock(&rpc_authflavor_lock);
  66         if (auth_flavors[flavor] == ops) {
  67                 auth_flavors[flavor] = NULL;
  68                 ret = 0;
  69         }
  70         spin_unlock(&rpc_authflavor_lock);
  71         return ret;
  72 }
  73 EXPORT_SYMBOL_GPL(rpcauth_unregister);
  74
  75 struct rpc_auth *
  76 rpcauth_create(rpc_authflavor_t pseudoflavor, struct rpc_clnt *clnt)
  77 {
  78         struct rpc_auth         *auth;
  79         const struct rpc_authops *ops;
  80         u32                     flavor = pseudoflavor_to_flavor(pseudoflavor);
  81
  82         auth = ERR_PTR(-EINVAL);
  83         if (flavor >= RPC_AUTH_MAXFLAVOR)
  84                 goto out;
  85
  86         if ((ops = auth_flavors[flavor]) == NULL)
  87                 request_module("rpc-auth-%u", flavor);
  88         spin_lock(&rpc_authflavor_lock);
  89         ops = auth_flavors[flavor];
  90         if (ops == NULL || !try_module_get(ops->owner)) {
  91                 spin_unlock(&rpc_authflavor_lock);
  92                 goto out;
  93         }
  94         spin_unlock(&rpc_authflavor_lock);
  95         auth = ops->create(clnt, pseudoflavor);
  96         module_put(ops->owner);
  97         if (IS_ERR(auth))
  98                 return auth;
  99         if (clnt->cl_auth)
 100                 rpcauth_release(clnt->cl_auth);
 101         clnt->cl_auth = auth;
 102
 103 out:
 104         return auth;
 105 }
 106 EXPORT_SYMBOL_GPL(rpcauth_create);
 107
 108 void
 109 rpcauth_release(struct rpc_auth *auth)
 110 {
 111         if (!atomic_dec_and_test(&auth->au_count))
 112                 return;
 113         auth->au_ops->destroy(auth);
 114 }
 115
 116 static DEFINE_SPINLOCK(rpc_credcache_lock);
 117
 118 static void
 119 rpcauth_unhash_cred_locked(struct rpc_cred *cred)
 120 {
 121         hlist_del_rcu(&cred->cr_hash);
 122         smp_mb__before_clear_bit();
 123         clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
 124 }
 125
 126 static int
 127 rpcauth_unhash_cred(struct rpc_cred *cred)
 128 {
 129         spinlock_t *cache_lock;
 130         int ret;
 131
 132         cache_lock = &cred->cr_auth->au_credcache->lock;
 133         spin_lock(cache_lock);
 134         ret = atomic_read(&cred->cr_count) == 0;
 135         if (ret)
 136                 rpcauth_unhash_cred_locked(cred);
 137         spin_unlock(cache_lock);
 138         return ret;
 139 }
 140
 141 /*
 142  * Initialize RPC credential cache
 143  */
 144 int
 145 rpcauth_init_credcache(struct rpc_auth *auth)
 146 {
 147         struct rpc_cred_cache *new;
 148         unsigned int hashsize;
 149         int i;
 150
 151         new = kmalloc(sizeof(*new), GFP_KERNEL);
 152         if (!new)
 153                 return -ENOMEM;
 154         new->hashbits = RPC_CREDCACHE_HASHBITS;
 155         hashsize = 1U << new->hashbits;
 156         for (i = 0; i < hashsize; i++)
 157                 INIT_HLIST_HEAD(&new->hashtable[i]);
 158         spin_lock_init(&new->lock);
 159         auth->au_credcache = new;
 160         return 0;
 161 }
 162 EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
 163
 164 /*
 165  * Destroy a list of credentials
 166  */
 167 static inline
 168 void rpcauth_destroy_credlist(struct list_head *head)
 169 {
 170         struct rpc_cred *cred;
 171
 172         while (!list_empty(head)) {
 173                 cred = list_entry(head->next, struct rpc_cred, cr_lru);
 174                 list_del_init(&cred->cr_lru);
 175                 put_rpccred(cred);
 176         }
 177 }
 178
 179 /*
 180  * Clear the RPC credential cache, and delete those credentials
 181  * that are not referenced.
 182  */
 183 void
 184 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
 185 {
 186         LIST_HEAD(free);
 187         struct hlist_head *head;
 188         struct rpc_cred *cred;
 189         unsigned int hashsize = 1U << cache->hashbits;
 190         int             i;
 191
 192         spin_lock(&rpc_credcache_lock);
 193         spin_lock(&cache->lock);
 194         for (i = 0; i < hashsize; i++) {
 195                 head = &cache->hashtable[i];
 196                 while (!hlist_empty(head)) {
 197                         cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
 198                         get_rpccred(cred);
 199                         if (!list_empty(&cred->cr_lru)) {
 200                                 list_del(&cred->cr_lru);
 201                                 number_cred_unused--;
 202                         }
 203                         list_add_tail(&cred->cr_lru, &free);
 204                         rpcauth_unhash_cred_locked(cred);
 205                 }
 206         }
 207         spin_unlock(&cache->lock);
 208         spin_unlock(&rpc_credcache_lock);
 209         rpcauth_destroy_credlist(&free);
 210 }
 211
 212 /*
 213  * Destroy the RPC credential cache
 214  */
 215 void
 216 rpcauth_destroy_credcache(struct rpc_auth *auth)
 217 {
 218         struct rpc_cred_cache *cache = auth->au_credcache;
 219
 220         if (cache) {
 221                 auth->au_credcache = NULL;
 222                 rpcauth_clear_credcache(cache);
 223                 kfree(cache);
 224         }
 225 }
 226 EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
 227
 228
 229 #define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)
 230
 231 /*
 232  * Remove stale credentials. Avoid sleeping inside the loop.
 233  */
 234 static int
 235 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
 236 {
 237         spinlock_t *cache_lock;
 238         struct rpc_cred *cred, *next;
 239         unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
 240
 241         list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {
 242
 243                 if (nr_to_scan-- == 0)
 244                         break;
 245                 /*
 246                  * Enforce a 60 second garbage collection moratorium
 247                  * Note that the cred_unused list must be time-ordered.
 248                  */
 249                 if (time_in_range(cred->cr_expire, expired, jiffies) &&
 250                     test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
 251                         return 0;
 252
 253                 list_del_init(&cred->cr_lru);
 254                 number_cred_unused--;
 255                 if (atomic_read(&cred->cr_count) != 0)
 256                         continue;
 257
 258                 cache_lock = &cred->cr_auth->au_credcache->lock;
 259                 spin_lock(cache_lock);
 260                 if (atomic_read(&cred->cr_count) == 0) {
 261                         get_rpccred(cred);
 262                         list_add_tail(&cred->cr_lru, free);
 263                         rpcauth_unhash_cred_locked(cred);
 264                 }
 265                 spin_unlock(cache_lock);
 266         }
 267         return (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
 268 }
 269
 270 /*
 271  * Run memory cache shrinker.
 272  */
 273 static int
 274 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
 275 {
 276         LIST_HEAD(free);
 277         int res;
 278
 279         if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
 280                 return (nr_to_scan == 0) ? 0 : -1;
 281         if (list_empty(&cred_unused))
 282                 return 0;
 283         spin_lock(&rpc_credcache_lock);
 284         res = rpcauth_prune_expired(&free, nr_to_scan);
 285         spin_unlock(&rpc_credcache_lock);
 286         rpcauth_destroy_credlist(&free);
 287         return res;
 288 }
 289
 290 /*
 291  * Look up a process' credentials in the authentication cache
 292  */
 293 struct rpc_cred *
 294 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
 295                 int flags)
 296 {
 297         LIST_HEAD(free);
 298         struct rpc_cred_cache *cache = auth->au_credcache;
 299         struct hlist_node *pos;
 300         struct rpc_cred *cred = NULL,
 301                         *entry, *new;
 302         unsigned int nr;
 303
 304         nr = hash_long(acred->uid, cache->hashbits);
 305
 306         rcu_read_lock();
 307         hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
 308                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 309                         continue;
 310                 spin_lock(&cache->lock);
 311                 if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
 312                         spin_unlock(&cache->lock);
 313                         continue;
 314                 }
 315                 cred = get_rpccred(entry);
 316                 spin_unlock(&cache->lock);
 317                 break;
 318         }
 319         rcu_read_unlock();
 320
 321         if (cred != NULL)
 322                 goto found;
 323
 324         new = auth->au_ops->crcreate(auth, acred, flags);
 325         if (IS_ERR(new)) {
 326                 cred = new;
 327                 goto out;
 328         }
 329
 330         spin_lock(&cache->lock);
 331         hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
 332                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 333                         continue;
 334                 cred = get_rpccred(entry);
 335                 break;
 336         }
 337         if (cred == NULL) {
 338                 cred = new;
 339                 set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
 340                 hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
 341         } else
 342                 list_add_tail(&new->cr_lru, &free);
 343         spin_unlock(&cache->lock);
 344 found:
 345         if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
 346             cred->cr_ops->cr_init != NULL &&
 347             !(flags & RPCAUTH_LOOKUP_NEW)) {
 348                 int res = cred->cr_ops->cr_init(auth, cred);
 349                 if (res < 0) {
 350                         put_rpccred(cred);
 351                         cred = ERR_PTR(res);
 352                 }
 353         }
 354         rpcauth_destroy_credlist(&free);
 355 out:
 356         return cred;
 357 }
 358 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
 359
 360 struct rpc_cred *
 361 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
 362 {
 363         struct auth_cred acred;
 364         struct rpc_cred *ret;
 365         const struct cred *cred = current_cred();
 366
 367         dprintk("RPC:       looking up %s cred\n",
 368                 auth->au_ops->au_name);
 369
 370         memset(&acred, 0, sizeof(acred));
 371         acred.uid = cred->fsuid;
 372         acred.gid = cred->fsgid;
 373         acred.group_info = get_group_info(((struct cred *)cred)->group_info);
 374
 375         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
 376         put_group_info(acred.group_info);
 377         return ret;
 378 }
 379
 380 void
 381 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
 382                   struct rpc_auth *auth, const struct rpc_credops *ops)
 383 {
 384         INIT_HLIST_NODE(&cred->cr_hash);
 385         INIT_LIST_HEAD(&cred->cr_lru);
 386         atomic_set(&cred->cr_count, 1);
 387         cred->cr_auth = auth;
 388         cred->cr_ops = ops;
 389         cred->cr_expire = jiffies;
 390 #ifdef RPC_DEBUG
 391         cred->cr_magic = RPCAUTH_CRED_MAGIC;
 392 #endif
 393         cred->cr_uid = acred->uid;
 394 }
 395 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
 396
 397 void
 398 rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred, int lookupflags)
 399 {
 400         task->tk_msg.rpc_cred = get_rpccred(cred);
 401         dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
 402                         cred->cr_auth->au_ops->au_name, cred);
 403 }
 404 EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
 405
 406 static void
 407 rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
 408 {
 409         struct rpc_auth *auth = task->tk_client->cl_auth;
 410         struct auth_cred acred = {
 411                 .uid = 0,
 412                 .gid = 0,
 413         };
 414         struct rpc_cred *ret;
 415
 416         dprintk("RPC: %5u looking up %s cred\n",
 417                 task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
 418         ret = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
 419         if (!IS_ERR(ret))
 420                 task->tk_msg.rpc_cred = ret;
 421         else
 422                 task->tk_status = PTR_ERR(ret);
 423 }
 424
 425 static void
 426 rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
 427 {
 428         struct rpc_auth *auth = task->tk_client->cl_auth;
 429         struct rpc_cred *ret;
 430
 431         dprintk("RPC: %5u looking up %s cred\n",
 432                 task->tk_pid, auth->au_ops->au_name);
 433         ret = rpcauth_lookupcred(auth, lookupflags);
 434         if (!IS_ERR(ret))
 435                 task->tk_msg.rpc_cred = ret;
 436         else
 437                 task->tk_status = PTR_ERR(ret);
 438 }
 439
 440 void
 441 rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
 442 {
 443         int lookupflags = 0;
 444
 445         if (flags & RPC_TASK_ASYNC)
 446                 lookupflags |= RPCAUTH_LOOKUP_NEW;
 447         if (cred != NULL)
 448                 cred->cr_ops->crbind(task, cred, lookupflags);
 449         else if (flags & RPC_TASK_ROOTCREDS)
 450                 rpcauth_bind_root_cred(task, lookupflags);
 451         else
 452                 rpcauth_bind_new_cred(task, lookupflags);
 453 }
 454
 455 void
 456 put_rpccred(struct rpc_cred *cred)
 457 {
 458         /* Fast path for unhashed credentials */
 459         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
 460                 if (atomic_dec_and_test(&cred->cr_count))
 461                         cred->cr_ops->crdestroy(cred);
 462                 return;
 463         }
 464
 465         if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
 466                 return;
 467         if (!list_empty(&cred->cr_lru)) {
 468                 number_cred_unused--;
 469                 list_del_init(&cred->cr_lru);
 470         }
 471         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
 472                 if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
 473                         cred->cr_expire = jiffies;
 474                         list_add_tail(&cred->cr_lru, &cred_unused);
 475                         number_cred_unused++;
 476                         goto out_nodestroy;
 477                 }
 478                 if (!rpcauth_unhash_cred(cred)) {
 479                         /* We were hashed and someone looked us up... */
 480                         goto out_nodestroy;
 481                 }
 482         }
 483         spin_unlock(&rpc_credcache_lock);
 484         cred->cr_ops->crdestroy(cred);
 485         return;
 486 out_nodestroy:
 487         spin_unlock(&rpc_credcache_lock);
 488 }
 489 EXPORT_SYMBOL_GPL(put_rpccred);
 490
 491 void
 492 rpcauth_unbindcred(struct rpc_task *task)
 493 {
 494         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 495
 496         dprintk("RPC: %5u releasing %s cred %p\n",
 497                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 498
 499         put_rpccred(cred);
 500         task->tk_msg.rpc_cred = NULL;
 501 }
 502
 503 __be32 *
 504 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
 505 {
 506         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 507
 508         dprintk("RPC: %5u marshaling %s cred %p\n",
 509                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 510
 511         return cred->cr_ops->crmarshal(task, p);
 512 }
 513
 514 __be32 *
 515 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
 516 {
 517         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 518
 519         dprintk("RPC: %5u validating %s cred %p\n",
 520                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 521
 522         return cred->cr_ops->crvalidate(task, p);
 523 }
 524
 525 int
 526 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
 527                 __be32 *data, void *obj)
 528 {
 529         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 530
 531         dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
 532                         task->tk_pid, cred->cr_ops->cr_name, cred);
 533         if (cred->cr_ops->crwrap_req)
 534                 return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
 535         /* By default, we encode the arguments normally. */
 536         return encode(rqstp, data, obj);
 537 }
 538
 539 int
 540 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
 541                 __be32 *data, void *obj)
 542 {
 543         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 544
 545         dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
 546                         task->tk_pid, cred->cr_ops->cr_name, cred);
 547         if (cred->cr_ops->crunwrap_resp)
 548                 return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
 549                                                    data, obj);
 550         /* By default, we decode the arguments normally. */
 551         return decode(rqstp, data, obj);
 552 }
 553
 554 int
 555 rpcauth_refreshcred(struct rpc_task *task)
 556 {
 557         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 558         int err;
 559
 560         dprintk("RPC: %5u refreshing %s cred %p\n",
 561                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 562
 563         err = cred->cr_ops->crrefresh(task);
 564         if (err < 0)
 565                 task->tk_status = err;
 566         return err;
 567 }
 568
 569 void
 570 rpcauth_invalcred(struct rpc_task *task)
 571 {
 572         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 573
 574         dprintk("RPC: %5u invalidating %s cred %p\n",
 575                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 576         if (cred)
 577                 clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
 578 }
 579
 580 int
 581 rpcauth_uptodatecred(struct rpc_task *task)
 582 {
 583         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 584
 585         return cred == NULL ||
 586                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
 587 }
 588
 589 static struct shrinker rpc_cred_shrinker = {
 590         .shrink = rpcauth_cache_shrinker,
 591         .seeks = DEFAULT_SEEKS,
 592 };
 593
 594 int __init rpcauth_init_module(void)
 595 {
 596         int err;
 597
 598         err = rpc_init_authunix();
 599         if (err < 0)
 600                 goto out1;
 601         err = rpc_init_generic_auth();
 602         if (err < 0)
 603                 goto out2;
 604         register_shrinker(&rpc_cred_shrinker);
 605         return 0;
 606 out2:
 607         rpc_destroy_authunix();
 608 out1:
 609         return err;
 610 }
 611
 612 void __exit rpcauth_remove_module(void)
 613 {
 614         rpc_destroy_authunix();
 615         rpc_destroy_generic_auth();
 616         unregister_shrinker(&rpc_cred_shrinker);
 617 }