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