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 void
 127 rpcauth_unhash_cred(struct rpc_cred *cred)
 128 {
 129         spinlock_t *cache_lock;
 130
 131         cache_lock = &cred->cr_auth->au_credcache->lock;
 132         spin_lock(cache_lock);
 133         if (atomic_read(&cred->cr_count) == 0)
 134                 rpcauth_unhash_cred_locked(cred);
 135         spin_unlock(cache_lock);
 136 }
 137
 138 /*
 139  * Initialize RPC credential cache
 140  */
 141 int
 142 rpcauth_init_credcache(struct rpc_auth *auth)
 143 {
 144         struct rpc_cred_cache *new;
 145         int i;
 146
 147         new = kmalloc(sizeof(*new), GFP_KERNEL);
 148         if (!new)
 149                 return -ENOMEM;
 150         for (i = 0; i < RPC_CREDCACHE_NR; i++)
 151                 INIT_HLIST_HEAD(&new->hashtable[i]);
 152         spin_lock_init(&new->lock);
 153         auth->au_credcache = new;
 154         return 0;
 155 }
 156 EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
 157
 158 /*
 159  * Destroy a list of credentials
 160  */
 161 static inline
 162 void rpcauth_destroy_credlist(struct list_head *head)
 163 {
 164         struct rpc_cred *cred;
 165
 166         while (!list_empty(head)) {
 167                 cred = list_entry(head->next, struct rpc_cred, cr_lru);
 168                 list_del_init(&cred->cr_lru);
 169                 put_rpccred(cred);
 170         }
 171 }
 172
 173 /*
 174  * Clear the RPC credential cache, and delete those credentials
 175  * that are not referenced.
 176  */
 177 void
 178 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
 179 {
 180         LIST_HEAD(free);
 181         struct hlist_head *head;
 182         struct rpc_cred *cred;
 183         int             i;
 184
 185         spin_lock(&rpc_credcache_lock);
 186         spin_lock(&cache->lock);
 187         for (i = 0; i < RPC_CREDCACHE_NR; i++) {
 188                 head = &cache->hashtable[i];
 189                 while (!hlist_empty(head)) {
 190                         cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
 191                         get_rpccred(cred);
 192                         if (!list_empty(&cred->cr_lru)) {
 193                                 list_del(&cred->cr_lru);
 194                                 number_cred_unused--;
 195                         }
 196                         list_add_tail(&cred->cr_lru, &free);
 197                         rpcauth_unhash_cred_locked(cred);
 198                 }
 199         }
 200         spin_unlock(&cache->lock);
 201         spin_unlock(&rpc_credcache_lock);
 202         rpcauth_destroy_credlist(&free);
 203 }
 204
 205 /*
 206  * Destroy the RPC credential cache
 207  */
 208 void
 209 rpcauth_destroy_credcache(struct rpc_auth *auth)
 210 {
 211         struct rpc_cred_cache *cache = auth->au_credcache;
 212
 213         if (cache) {
 214                 auth->au_credcache = NULL;
 215                 rpcauth_clear_credcache(cache);
 216                 kfree(cache);
 217         }
 218 }
 219 EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
 220
 221
 222 #define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)
 223
 224 /*
 225  * Remove stale credentials. Avoid sleeping inside the loop.
 226  */
 227 static int
 228 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
 229 {
 230         spinlock_t *cache_lock;
 231         struct rpc_cred *cred, *next;
 232         unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
 233
 234         list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {
 235
 236                 /* Enforce a 60 second garbage collection moratorium */
 237                 if (time_in_range(cred->cr_expire, expired, jiffies) &&
 238                     test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
 239                         continue;
 240
 241                 list_del_init(&cred->cr_lru);
 242                 number_cred_unused--;
 243                 if (atomic_read(&cred->cr_count) != 0)
 244                         continue;
 245
 246                 cache_lock = &cred->cr_auth->au_credcache->lock;
 247                 spin_lock(cache_lock);
 248                 if (atomic_read(&cred->cr_count) == 0) {
 249                         get_rpccred(cred);
 250                         list_add_tail(&cred->cr_lru, free);
 251                         rpcauth_unhash_cred_locked(cred);
 252                         nr_to_scan--;
 253                 }
 254                 spin_unlock(cache_lock);
 255                 if (nr_to_scan == 0)
 256                         break;
 257         }
 258         return nr_to_scan;
 259 }
 260
 261 /*
 262  * Run memory cache shrinker.
 263  */
 264 static int
 265 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
 266 {
 267         LIST_HEAD(free);
 268         int res;
 269
 270         if (list_empty(&cred_unused))
 271                 return 0;
 272         spin_lock(&rpc_credcache_lock);
 273         nr_to_scan = rpcauth_prune_expired(&free, nr_to_scan);
 274         res = (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
 275         spin_unlock(&rpc_credcache_lock);
 276         rpcauth_destroy_credlist(&free);
 277         return res;
 278 }
 279
 280 /*
 281  * Look up a process' credentials in the authentication cache
 282  */
 283 struct rpc_cred *
 284 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
 285                 int flags)
 286 {
 287         LIST_HEAD(free);
 288         struct rpc_cred_cache *cache = auth->au_credcache;
 289         struct hlist_node *pos;
 290         struct rpc_cred *cred = NULL,
 291                         *entry, *new;
 292         unsigned int nr;
 293
 294         nr = hash_long(acred->uid, RPC_CREDCACHE_HASHBITS);
 295
 296         rcu_read_lock();
 297         hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
 298                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 299                         continue;
 300                 spin_lock(&cache->lock);
 301                 if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
 302                         spin_unlock(&cache->lock);
 303                         continue;
 304                 }
 305                 cred = get_rpccred(entry);
 306                 spin_unlock(&cache->lock);
 307                 break;
 308         }
 309         rcu_read_unlock();
 310
 311         if (cred != NULL)
 312                 goto found;
 313
 314         new = auth->au_ops->crcreate(auth, acred, flags);
 315         if (IS_ERR(new)) {
 316                 cred = new;
 317                 goto out;
 318         }
 319
 320         spin_lock(&cache->lock);
 321         hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
 322                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 323                         continue;
 324                 cred = get_rpccred(entry);
 325                 break;
 326         }
 327         if (cred == NULL) {
 328                 cred = new;
 329                 set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
 330                 hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
 331         } else
 332                 list_add_tail(&new->cr_lru, &free);
 333         spin_unlock(&cache->lock);
 334 found:
 335         if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags)
 336                         && cred->cr_ops->cr_init != NULL
 337                         && !(flags & RPCAUTH_LOOKUP_NEW)) {
 338                 int res = cred->cr_ops->cr_init(auth, cred);
 339                 if (res < 0) {
 340                         put_rpccred(cred);
 341                         cred = ERR_PTR(res);
 342                 }
 343         }
 344         rpcauth_destroy_credlist(&free);
 345 out:
 346         return cred;
 347 }
 348 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
 349
 350 struct rpc_cred *
 351 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
 352 {
 353         struct auth_cred acred = {
 354                 .uid = current->fsuid,
 355                 .gid = current->fsgid,
 356                 .group_info = current->group_info,
 357         };
 358         struct rpc_cred *ret;
 359
 360         dprintk("RPC:       looking up %s cred\n",
 361                 auth->au_ops->au_name);
 362         get_group_info(acred.group_info);
 363         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
 364         put_group_info(acred.group_info);
 365         return ret;
 366 }
 367
 368 void
 369 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
 370                   struct rpc_auth *auth, const struct rpc_credops *ops)
 371 {
 372         INIT_HLIST_NODE(&cred->cr_hash);
 373         INIT_LIST_HEAD(&cred->cr_lru);
 374         atomic_set(&cred->cr_count, 1);
 375         cred->cr_auth = auth;
 376         cred->cr_ops = ops;
 377         cred->cr_expire = jiffies;
 378 #ifdef RPC_DEBUG
 379         cred->cr_magic = RPCAUTH_CRED_MAGIC;
 380 #endif
 381         cred->cr_uid = acred->uid;
 382 }
 383 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
 384
 385 void
 386 rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred)
 387 {
 388         task->tk_msg.rpc_cred = get_rpccred(cred);
 389         dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
 390                         cred->cr_auth->au_ops->au_name, cred);
 391 }
 392 EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
 393
 394 static void
 395 rpcauth_bind_root_cred(struct rpc_task *task)
 396 {
 397         struct rpc_auth *auth = task->tk_client->cl_auth;
 398         struct auth_cred acred = {
 399                 .uid = 0,
 400                 .gid = 0,
 401         };
 402         struct rpc_cred *ret;
 403
 404         dprintk("RPC: %5u looking up %s cred\n",
 405                 task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
 406         ret = auth->au_ops->lookup_cred(auth, &acred, 0);
 407         if (!IS_ERR(ret))
 408                 task->tk_msg.rpc_cred = ret;
 409         else
 410                 task->tk_status = PTR_ERR(ret);
 411 }
 412
 413 static void
 414 rpcauth_bind_new_cred(struct rpc_task *task)
 415 {
 416         struct rpc_auth *auth = task->tk_client->cl_auth;
 417         struct rpc_cred *ret;
 418
 419         dprintk("RPC: %5u looking up %s cred\n",
 420                 task->tk_pid, auth->au_ops->au_name);
 421         ret = rpcauth_lookupcred(auth, 0);
 422         if (!IS_ERR(ret))
 423                 task->tk_msg.rpc_cred = ret;
 424         else
 425                 task->tk_status = PTR_ERR(ret);
 426 }
 427
 428 void
 429 rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
 430 {
 431         if (cred != NULL)
 432                 cred->cr_ops->crbind(task, cred);
 433         else if (flags & RPC_TASK_ROOTCREDS)
 434                 rpcauth_bind_root_cred(task);
 435         else
 436                 rpcauth_bind_new_cred(task);
 437 }
 438
 439 void
 440 put_rpccred(struct rpc_cred *cred)
 441 {
 442         /* Fast path for unhashed credentials */
 443         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
 444                 goto need_lock;
 445
 446         if (!atomic_dec_and_test(&cred->cr_count))
 447                 return;
 448         goto out_destroy;
 449 need_lock:
 450         if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
 451                 return;
 452         if (!list_empty(&cred->cr_lru)) {
 453                 number_cred_unused--;
 454                 list_del_init(&cred->cr_lru);
 455         }
 456         if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
 457                 rpcauth_unhash_cred(cred);
 458         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
 459                 cred->cr_expire = jiffies;
 460                 list_add_tail(&cred->cr_lru, &cred_unused);
 461                 number_cred_unused++;
 462                 spin_unlock(&rpc_credcache_lock);
 463                 return;
 464         }
 465         spin_unlock(&rpc_credcache_lock);
 466 out_destroy:
 467         cred->cr_ops->crdestroy(cred);
 468 }
 469 EXPORT_SYMBOL_GPL(put_rpccred);
 470
 471 void
 472 rpcauth_unbindcred(struct rpc_task *task)
 473 {
 474         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 475
 476         dprintk("RPC: %5u releasing %s cred %p\n",
 477                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 478
 479         put_rpccred(cred);
 480         task->tk_msg.rpc_cred = NULL;
 481 }
 482
 483 __be32 *
 484 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
 485 {
 486         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 487
 488         dprintk("RPC: %5u marshaling %s cred %p\n",
 489                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 490
 491         return cred->cr_ops->crmarshal(task, p);
 492 }
 493
 494 __be32 *
 495 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
 496 {
 497         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 498
 499         dprintk("RPC: %5u validating %s cred %p\n",
 500                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 501
 502         return cred->cr_ops->crvalidate(task, p);
 503 }
 504
 505 int
 506 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
 507                 __be32 *data, void *obj)
 508 {
 509         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 510
 511         dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
 512                         task->tk_pid, cred->cr_ops->cr_name, cred);
 513         if (cred->cr_ops->crwrap_req)
 514                 return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
 515         /* By default, we encode the arguments normally. */
 516         return rpc_call_xdrproc(encode, rqstp, data, obj);
 517 }
 518
 519 int
 520 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
 521                 __be32 *data, void *obj)
 522 {
 523         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 524
 525         dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
 526                         task->tk_pid, cred->cr_ops->cr_name, cred);
 527         if (cred->cr_ops->crunwrap_resp)
 528                 return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
 529                                                    data, obj);
 530         /* By default, we decode the arguments normally. */
 531         return rpc_call_xdrproc(decode, rqstp, data, obj);
 532 }
 533
 534 int
 535 rpcauth_refreshcred(struct rpc_task *task)
 536 {
 537         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 538         int err;
 539
 540         dprintk("RPC: %5u refreshing %s cred %p\n",
 541                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 542
 543         err = cred->cr_ops->crrefresh(task);
 544         if (err < 0)
 545                 task->tk_status = err;
 546         return err;
 547 }
 548
 549 void
 550 rpcauth_invalcred(struct rpc_task *task)
 551 {
 552         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 553
 554         dprintk("RPC: %5u invalidating %s cred %p\n",
 555                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 556         if (cred)
 557                 clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
 558 }
 559
 560 int
 561 rpcauth_uptodatecred(struct rpc_task *task)
 562 {
 563         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 564
 565         return cred == NULL ||
 566                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
 567 }
 568
 569 static struct shrinker rpc_cred_shrinker = {
 570         .shrink = rpcauth_cache_shrinker,
 571         .seeks = DEFAULT_SEEKS,
 572 };
 573
 574 void __init rpcauth_init_module(void)
 575 {
 576         rpc_init_authunix();
 577         rpc_init_generic_auth();
 578         register_shrinker(&rpc_cred_shrinker);
 579 }
 580
 581 void __exit rpcauth_remove_module(void)
 582 {
 583         unregister_shrinker(&rpc_cred_shrinker);
 584 }