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         int i;
 149
 150         new = kmalloc(sizeof(*new), GFP_KERNEL);
 151         if (!new)
 152                 return -ENOMEM;
 153         for (i = 0; i < RPC_CREDCACHE_NR; i++)
 154                 INIT_HLIST_HEAD(&new->hashtable[i]);
 155         spin_lock_init(&new->lock);
 156         auth->au_credcache = new;
 157         return 0;
 158 }
 159 EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
 160
 161 /*
 162  * Destroy a list of credentials
 163  */
 164 static inline
 165 void rpcauth_destroy_credlist(struct list_head *head)
 166 {
 167         struct rpc_cred *cred;
 168
 169         while (!list_empty(head)) {
 170                 cred = list_entry(head->next, struct rpc_cred, cr_lru);
 171                 list_del_init(&cred->cr_lru);
 172                 put_rpccred(cred);
 173         }
 174 }
 175
 176 /*
 177  * Clear the RPC credential cache, and delete those credentials
 178  * that are not referenced.
 179  */
 180 void
 181 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
 182 {
 183         LIST_HEAD(free);
 184         struct hlist_head *head;
 185         struct rpc_cred *cred;
 186         int             i;
 187
 188         spin_lock(&rpc_credcache_lock);
 189         spin_lock(&cache->lock);
 190         for (i = 0; i < RPC_CREDCACHE_NR; i++) {
 191                 head = &cache->hashtable[i];
 192                 while (!hlist_empty(head)) {
 193                         cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
 194                         get_rpccred(cred);
 195                         if (!list_empty(&cred->cr_lru)) {
 196                                 list_del(&cred->cr_lru);
 197                                 number_cred_unused--;
 198                         }
 199                         list_add_tail(&cred->cr_lru, &free);
 200                         rpcauth_unhash_cred_locked(cred);
 201                 }
 202         }
 203         spin_unlock(&cache->lock);
 204         spin_unlock(&rpc_credcache_lock);
 205         rpcauth_destroy_credlist(&free);
 206 }
 207
 208 /*
 209  * Destroy the RPC credential cache
 210  */
 211 void
 212 rpcauth_destroy_credcache(struct rpc_auth *auth)
 213 {
 214         struct rpc_cred_cache *cache = auth->au_credcache;
 215
 216         if (cache) {
 217                 auth->au_credcache = NULL;
 218                 rpcauth_clear_credcache(cache);
 219                 kfree(cache);
 220         }
 221 }
 222 EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
 223
 224
 225 #define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)
 226
 227 /*
 228  * Remove stale credentials. Avoid sleeping inside the loop.
 229  */
 230 static int
 231 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
 232 {
 233         spinlock_t *cache_lock;
 234         struct rpc_cred *cred, *next;
 235         unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
 236
 237         list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {
 238
 239                 if (nr_to_scan-- == 0)
 240                         break;
 241                 /*
 242                  * Enforce a 60 second garbage collection moratorium
 243                  * Note that the cred_unused list must be time-ordered.
 244                  */
 245                 if (time_in_range(cred->cr_expire, expired, jiffies) &&
 246                     test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
 247                         return 0;
 248
 249                 list_del_init(&cred->cr_lru);
 250                 number_cred_unused--;
 251                 if (atomic_read(&cred->cr_count) != 0)
 252                         continue;
 253
 254                 cache_lock = &cred->cr_auth->au_credcache->lock;
 255                 spin_lock(cache_lock);
 256                 if (atomic_read(&cred->cr_count) == 0) {
 257                         get_rpccred(cred);
 258                         list_add_tail(&cred->cr_lru, free);
 259                         rpcauth_unhash_cred_locked(cred);
 260                 }
 261                 spin_unlock(cache_lock);
 262         }
 263         return (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
 264 }
 265
 266 /*
 267  * Run memory cache shrinker.
 268  */
 269 static int
 270 rpcauth_cache_shrinker(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
 271 {
 272         LIST_HEAD(free);
 273         int res;
 274
 275         if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
 276                 return (nr_to_scan == 0) ? 0 : -1;
 277         if (list_empty(&cred_unused))
 278                 return 0;
 279         spin_lock(&rpc_credcache_lock);
 280         res = rpcauth_prune_expired(&free, nr_to_scan);
 281         spin_unlock(&rpc_credcache_lock);
 282         rpcauth_destroy_credlist(&free);
 283         return res;
 284 }
 285
 286 /*
 287  * Look up a process' credentials in the authentication cache
 288  */
 289 struct rpc_cred *
 290 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
 291                 int flags)
 292 {
 293         LIST_HEAD(free);
 294         struct rpc_cred_cache *cache = auth->au_credcache;
 295         struct hlist_node *pos;
 296         struct rpc_cred *cred = NULL,
 297                         *entry, *new;
 298         unsigned int nr;
 299
 300         nr = hash_long(acred->uid, RPC_CREDCACHE_HASHBITS);
 301
 302         rcu_read_lock();
 303         hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
 304                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 305                         continue;
 306                 spin_lock(&cache->lock);
 307                 if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
 308                         spin_unlock(&cache->lock);
 309                         continue;
 310                 }
 311                 cred = get_rpccred(entry);
 312                 spin_unlock(&cache->lock);
 313                 break;
 314         }
 315         rcu_read_unlock();
 316
 317         if (cred != NULL)
 318                 goto found;
 319
 320         new = auth->au_ops->crcreate(auth, acred, flags);
 321         if (IS_ERR(new)) {
 322                 cred = new;
 323                 goto out;
 324         }
 325
 326         spin_lock(&cache->lock);
 327         hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
 328                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 329                         continue;
 330                 cred = get_rpccred(entry);
 331                 break;
 332         }
 333         if (cred == NULL) {
 334                 cred = new;
 335                 set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
 336                 hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
 337         } else
 338                 list_add_tail(&new->cr_lru, &free);
 339         spin_unlock(&cache->lock);
 340 found:
 341         if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
 342             cred->cr_ops->cr_init != NULL &&
 343             !(flags & RPCAUTH_LOOKUP_NEW)) {
 344                 int res = cred->cr_ops->cr_init(auth, cred);
 345                 if (res < 0) {
 346                         put_rpccred(cred);
 347                         cred = ERR_PTR(res);
 348                 }
 349         }
 350         rpcauth_destroy_credlist(&free);
 351 out:
 352         return cred;
 353 }
 354 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
 355
 356 struct rpc_cred *
 357 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
 358 {
 359         struct auth_cred acred;
 360         struct rpc_cred *ret;
 361         const struct cred *cred = current_cred();
 362
 363         dprintk("RPC:       looking up %s cred\n",
 364                 auth->au_ops->au_name);
 365
 366         memset(&acred, 0, sizeof(acred));
 367         acred.uid = cred->fsuid;
 368         acred.gid = cred->fsgid;
 369         acred.group_info = get_group_info(((struct cred *)cred)->group_info);
 370
 371         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
 372         put_group_info(acred.group_info);
 373         return ret;
 374 }
 375
 376 void
 377 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
 378                   struct rpc_auth *auth, const struct rpc_credops *ops)
 379 {
 380         INIT_HLIST_NODE(&cred->cr_hash);
 381         INIT_LIST_HEAD(&cred->cr_lru);
 382         atomic_set(&cred->cr_count, 1);
 383         cred->cr_auth = auth;
 384         cred->cr_ops = ops;
 385         cred->cr_expire = jiffies;
 386 #ifdef RPC_DEBUG
 387         cred->cr_magic = RPCAUTH_CRED_MAGIC;
 388 #endif
 389         cred->cr_uid = acred->uid;
 390 }
 391 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
 392
 393 void
 394 rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred, int lookupflags)
 395 {
 396         task->tk_msg.rpc_cred = get_rpccred(cred);
 397         dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
 398                         cred->cr_auth->au_ops->au_name, cred);
 399 }
 400 EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
 401
 402 static void
 403 rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
 404 {
 405         struct rpc_auth *auth = task->tk_client->cl_auth;
 406         struct auth_cred acred = {
 407                 .uid = 0,
 408                 .gid = 0,
 409         };
 410         struct rpc_cred *ret;
 411
 412         dprintk("RPC: %5u looking up %s cred\n",
 413                 task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
 414         ret = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
 415         if (!IS_ERR(ret))
 416                 task->tk_msg.rpc_cred = ret;
 417         else
 418                 task->tk_status = PTR_ERR(ret);
 419 }
 420
 421 static void
 422 rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
 423 {
 424         struct rpc_auth *auth = task->tk_client->cl_auth;
 425         struct rpc_cred *ret;
 426
 427         dprintk("RPC: %5u looking up %s cred\n",
 428                 task->tk_pid, auth->au_ops->au_name);
 429         ret = rpcauth_lookupcred(auth, lookupflags);
 430         if (!IS_ERR(ret))
 431                 task->tk_msg.rpc_cred = ret;
 432         else
 433                 task->tk_status = PTR_ERR(ret);
 434 }
 435
 436 void
 437 rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
 438 {
 439         int lookupflags = 0;
 440
 441         if (flags & RPC_TASK_ASYNC)
 442                 lookupflags |= RPCAUTH_LOOKUP_NEW;
 443         if (cred != NULL)
 444                 cred->cr_ops->crbind(task, cred, lookupflags);
 445         else if (flags & RPC_TASK_ROOTCREDS)
 446                 rpcauth_bind_root_cred(task, lookupflags);
 447         else
 448                 rpcauth_bind_new_cred(task, lookupflags);
 449 }
 450
 451 void
 452 put_rpccred(struct rpc_cred *cred)
 453 {
 454         /* Fast path for unhashed credentials */
 455         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
 456                 if (atomic_dec_and_test(&cred->cr_count))
 457                         cred->cr_ops->crdestroy(cred);
 458                 return;
 459         }
 460
 461         if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
 462                 return;
 463         if (!list_empty(&cred->cr_lru)) {
 464                 number_cred_unused--;
 465                 list_del_init(&cred->cr_lru);
 466         }
 467         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
 468                 if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
 469                         cred->cr_expire = jiffies;
 470                         list_add_tail(&cred->cr_lru, &cred_unused);
 471                         number_cred_unused++;
 472                         goto out_nodestroy;
 473                 }
 474                 if (!rpcauth_unhash_cred(cred)) {
 475                         /* We were hashed and someone looked us up... */
 476                         goto out_nodestroy;
 477                 }
 478         }
 479         spin_unlock(&rpc_credcache_lock);
 480         cred->cr_ops->crdestroy(cred);
 481         return;
 482 out_nodestroy:
 483         spin_unlock(&rpc_credcache_lock);
 484 }
 485 EXPORT_SYMBOL_GPL(put_rpccred);
 486
 487 void
 488 rpcauth_unbindcred(struct rpc_task *task)
 489 {
 490         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 491
 492         dprintk("RPC: %5u releasing %s cred %p\n",
 493                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 494
 495         put_rpccred(cred);
 496         task->tk_msg.rpc_cred = NULL;
 497 }
 498
 499 __be32 *
 500 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
 501 {
 502         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 503
 504         dprintk("RPC: %5u marshaling %s cred %p\n",
 505                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 506
 507         return cred->cr_ops->crmarshal(task, p);
 508 }
 509
 510 __be32 *
 511 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
 512 {
 513         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 514
 515         dprintk("RPC: %5u validating %s cred %p\n",
 516                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 517
 518         return cred->cr_ops->crvalidate(task, p);
 519 }
 520
 521 int
 522 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
 523                 __be32 *data, void *obj)
 524 {
 525         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 526
 527         dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
 528                         task->tk_pid, cred->cr_ops->cr_name, cred);
 529         if (cred->cr_ops->crwrap_req)
 530                 return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
 531         /* By default, we encode the arguments normally. */
 532         return encode(rqstp, data, obj);
 533 }
 534
 535 int
 536 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
 537                 __be32 *data, void *obj)
 538 {
 539         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 540
 541         dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
 542                         task->tk_pid, cred->cr_ops->cr_name, cred);
 543         if (cred->cr_ops->crunwrap_resp)
 544                 return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
 545                                                    data, obj);
 546         /* By default, we decode the arguments normally. */
 547         return decode(rqstp, data, obj);
 548 }
 549
 550 int
 551 rpcauth_refreshcred(struct rpc_task *task)
 552 {
 553         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 554         int err;
 555
 556         dprintk("RPC: %5u refreshing %s cred %p\n",
 557                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 558
 559         err = cred->cr_ops->crrefresh(task);
 560         if (err < 0)
 561                 task->tk_status = err;
 562         return err;
 563 }
 564
 565 void
 566 rpcauth_invalcred(struct rpc_task *task)
 567 {
 568         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 569
 570         dprintk("RPC: %5u invalidating %s cred %p\n",
 571                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 572         if (cred)
 573                 clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
 574 }
 575
 576 int
 577 rpcauth_uptodatecred(struct rpc_task *task)
 578 {
 579         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 580
 581         return cred == NULL ||
 582                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
 583 }
 584
 585 static struct shrinker rpc_cred_shrinker = {
 586         .shrink = rpcauth_cache_shrinker,
 587         .seeks = DEFAULT_SEEKS,
 588 };
 589
 590 void __init rpcauth_init_module(void)
 591 {
 592         rpc_init_authunix();
 593         rpc_init_generic_auth();
 594         register_shrinker(&rpc_cred_shrinker);
 595 }
 596
 597 void __exit rpcauth_remove_module(void)
 598 {
 599         unregister_shrinker(&rpc_cred_shrinker);
 600 }