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