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;
 232         unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
 233
 234         while (!list_empty(&cred_unused)) {
 235                 cred = list_entry(cred_unused.next, struct rpc_cred, cr_lru);
 236                 list_del_init(&cred->cr_lru);
 237                 number_cred_unused--;
 238                 if (atomic_read(&cred->cr_count) != 0)
 239                         continue;
 240                 /* Enforce a 5 second garbage collection moratorium */
 241                 if (time_in_range(cred->cr_expire, expired, jiffies) &&
 242                     test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0)
 243                         continue;
 244                 cache_lock = &cred->cr_auth->au_credcache->lock;
 245                 spin_lock(cache_lock);
 246                 if (atomic_read(&cred->cr_count) == 0) {
 247                         get_rpccred(cred);
 248                         list_add_tail(&cred->cr_lru, free);
 249                         rpcauth_unhash_cred_locked(cred);
 250                         nr_to_scan--;
 251                 }
 252                 spin_unlock(cache_lock);
 253                 if (nr_to_scan == 0)
 254                         break;
 255         }
 256         return nr_to_scan;
 257 }
 258
 259 /*
 260  * Run memory cache shrinker.
 261  */
 262 static int
 263 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
 264 {
 265         LIST_HEAD(free);
 266         int res;
 267
 268         if (list_empty(&cred_unused))
 269                 return 0;
 270         spin_lock(&rpc_credcache_lock);
 271         nr_to_scan = rpcauth_prune_expired(&free, nr_to_scan);
 272         res = (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
 273         spin_unlock(&rpc_credcache_lock);
 274         rpcauth_destroy_credlist(&free);
 275         return res;
 276 }
 277
 278 /*
 279  * Look up a process' credentials in the authentication cache
 280  */
 281 struct rpc_cred *
 282 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
 283                 int flags)
 284 {
 285         LIST_HEAD(free);
 286         struct rpc_cred_cache *cache = auth->au_credcache;
 287         struct hlist_node *pos;
 288         struct rpc_cred *cred = NULL,
 289                         *entry, *new;
 290         unsigned int nr;
 291
 292         nr = hash_long(acred->uid, RPC_CREDCACHE_HASHBITS);
 293
 294         rcu_read_lock();
 295         hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
 296                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 297                         continue;
 298                 spin_lock(&cache->lock);
 299                 if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
 300                         spin_unlock(&cache->lock);
 301                         continue;
 302                 }
 303                 cred = get_rpccred(entry);
 304                 spin_unlock(&cache->lock);
 305                 break;
 306         }
 307         rcu_read_unlock();
 308
 309         if (cred != NULL)
 310                 goto found;
 311
 312         new = auth->au_ops->crcreate(auth, acred, flags);
 313         if (IS_ERR(new)) {
 314                 cred = new;
 315                 goto out;
 316         }
 317
 318         spin_lock(&cache->lock);
 319         hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
 320                 if (!entry->cr_ops->crmatch(acred, entry, flags))
 321                         continue;
 322                 cred = get_rpccred(entry);
 323                 break;
 324         }
 325         if (cred == NULL) {
 326                 cred = new;
 327                 set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
 328                 hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
 329         } else
 330                 list_add_tail(&new->cr_lru, &free);
 331         spin_unlock(&cache->lock);
 332 found:
 333         if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags)
 334                         && cred->cr_ops->cr_init != NULL
 335                         && !(flags & RPCAUTH_LOOKUP_NEW)) {
 336                 int res = cred->cr_ops->cr_init(auth, cred);
 337                 if (res < 0) {
 338                         put_rpccred(cred);
 339                         cred = ERR_PTR(res);
 340                 }
 341         }
 342         rpcauth_destroy_credlist(&free);
 343 out:
 344         return cred;
 345 }
 346 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
 347
 348 struct rpc_cred *
 349 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
 350 {
 351         struct auth_cred acred = {
 352                 .uid = current->fsuid,
 353                 .gid = current->fsgid,
 354                 .group_info = current->group_info,
 355         };
 356         struct rpc_cred *ret;
 357
 358         dprintk("RPC:       looking up %s cred\n",
 359                 auth->au_ops->au_name);
 360         get_group_info(acred.group_info);
 361         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
 362         put_group_info(acred.group_info);
 363         return ret;
 364 }
 365
 366 void
 367 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
 368                   struct rpc_auth *auth, const struct rpc_credops *ops)
 369 {
 370         INIT_HLIST_NODE(&cred->cr_hash);
 371         INIT_LIST_HEAD(&cred->cr_lru);
 372         atomic_set(&cred->cr_count, 1);
 373         cred->cr_auth = auth;
 374         cred->cr_ops = ops;
 375         cred->cr_expire = jiffies;
 376 #ifdef RPC_DEBUG
 377         cred->cr_magic = RPCAUTH_CRED_MAGIC;
 378 #endif
 379         cred->cr_uid = acred->uid;
 380 }
 381 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
 382
 383 void
 384 rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred)
 385 {
 386         task->tk_msg.rpc_cred = get_rpccred(cred);
 387         dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
 388                         cred->cr_auth->au_ops->au_name, cred);
 389 }
 390 EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
 391
 392 static void
 393 rpcauth_bind_root_cred(struct rpc_task *task)
 394 {
 395         struct rpc_auth *auth = task->tk_client->cl_auth;
 396         struct auth_cred acred = {
 397                 .uid = 0,
 398                 .gid = 0,
 399         };
 400         struct rpc_cred *ret;
 401
 402         dprintk("RPC: %5u looking up %s cred\n",
 403                 task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
 404         ret = auth->au_ops->lookup_cred(auth, &acred, 0);
 405         if (!IS_ERR(ret))
 406                 task->tk_msg.rpc_cred = ret;
 407         else
 408                 task->tk_status = PTR_ERR(ret);
 409 }
 410
 411 static void
 412 rpcauth_bind_new_cred(struct rpc_task *task)
 413 {
 414         struct rpc_auth *auth = task->tk_client->cl_auth;
 415         struct rpc_cred *ret;
 416
 417         dprintk("RPC: %5u looking up %s cred\n",
 418                 task->tk_pid, auth->au_ops->au_name);
 419         ret = rpcauth_lookupcred(auth, 0);
 420         if (!IS_ERR(ret))
 421                 task->tk_msg.rpc_cred = ret;
 422         else
 423                 task->tk_status = PTR_ERR(ret);
 424 }
 425
 426 void
 427 rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
 428 {
 429         if (cred != NULL)
 430                 cred->cr_ops->crbind(task, cred);
 431         else if (flags & RPC_TASK_ROOTCREDS)
 432                 rpcauth_bind_root_cred(task);
 433         else
 434                 rpcauth_bind_new_cred(task);
 435 }
 436
 437 void
 438 put_rpccred(struct rpc_cred *cred)
 439 {
 440         /* Fast path for unhashed credentials */
 441         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
 442                 goto need_lock;
 443
 444         if (!atomic_dec_and_test(&cred->cr_count))
 445                 return;
 446         goto out_destroy;
 447 need_lock:
 448         if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
 449                 return;
 450         if (!list_empty(&cred->cr_lru)) {
 451                 number_cred_unused--;
 452                 list_del_init(&cred->cr_lru);
 453         }
 454         if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
 455                 rpcauth_unhash_cred(cred);
 456         else if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
 457                 cred->cr_expire = jiffies;
 458                 list_add_tail(&cred->cr_lru, &cred_unused);
 459                 number_cred_unused++;
 460                 spin_unlock(&rpc_credcache_lock);
 461                 return;
 462         }
 463         spin_unlock(&rpc_credcache_lock);
 464 out_destroy:
 465         cred->cr_ops->crdestroy(cred);
 466 }
 467 EXPORT_SYMBOL_GPL(put_rpccred);
 468
 469 void
 470 rpcauth_unbindcred(struct rpc_task *task)
 471 {
 472         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 473
 474         dprintk("RPC: %5u releasing %s cred %p\n",
 475                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 476
 477         put_rpccred(cred);
 478         task->tk_msg.rpc_cred = NULL;
 479 }
 480
 481 __be32 *
 482 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
 483 {
 484         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 485
 486         dprintk("RPC: %5u marshaling %s cred %p\n",
 487                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 488
 489         return cred->cr_ops->crmarshal(task, p);
 490 }
 491
 492 __be32 *
 493 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
 494 {
 495         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 496
 497         dprintk("RPC: %5u validating %s cred %p\n",
 498                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 499
 500         return cred->cr_ops->crvalidate(task, p);
 501 }
 502
 503 int
 504 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
 505                 __be32 *data, void *obj)
 506 {
 507         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 508
 509         dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
 510                         task->tk_pid, cred->cr_ops->cr_name, cred);
 511         if (cred->cr_ops->crwrap_req)
 512                 return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
 513         /* By default, we encode the arguments normally. */
 514         return rpc_call_xdrproc(encode, rqstp, data, obj);
 515 }
 516
 517 int
 518 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
 519                 __be32 *data, void *obj)
 520 {
 521         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 522
 523         dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
 524                         task->tk_pid, cred->cr_ops->cr_name, cred);
 525         if (cred->cr_ops->crunwrap_resp)
 526                 return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
 527                                                    data, obj);
 528         /* By default, we decode the arguments normally. */
 529         return rpc_call_xdrproc(decode, rqstp, data, obj);
 530 }
 531
 532 int
 533 rpcauth_refreshcred(struct rpc_task *task)
 534 {
 535         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 536         int err;
 537
 538         dprintk("RPC: %5u refreshing %s cred %p\n",
 539                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 540
 541         err = cred->cr_ops->crrefresh(task);
 542         if (err < 0)
 543                 task->tk_status = err;
 544         return err;
 545 }
 546
 547 void
 548 rpcauth_invalcred(struct rpc_task *task)
 549 {
 550         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 551
 552         dprintk("RPC: %5u invalidating %s cred %p\n",
 553                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 554         if (cred)
 555                 clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
 556 }
 557
 558 int
 559 rpcauth_uptodatecred(struct rpc_task *task)
 560 {
 561         struct rpc_cred *cred = task->tk_msg.rpc_cred;
 562
 563         return cred == NULL ||
 564                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
 565 }
 566
 567 static struct shrinker rpc_cred_shrinker = {
 568         .shrink = rpcauth_cache_shrinker,
 569         .seeks = DEFAULT_SEEKS,
 570 };
 571
 572 void __init rpcauth_init_module(void)
 573 {
 574         rpc_init_authunix();
 575         rpc_init_generic_auth();
 576         register_shrinker(&rpc_cred_shrinker);
 577 }
 578
 579 void __exit rpcauth_remove_module(void)
 580 {
 581         unregister_shrinker(&rpc_cred_shrinker);
 582 }