linux/net/sunrpc/auth.c
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   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
  22static DEFINE_SPINLOCK(rpc_authflavor_lock);
  23static 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
  29static LIST_HEAD(cred_unused);
  30static unsigned long number_cred_unused;
  31
  32static u32
  33pseudoflavor_to_flavor(u32 flavor) {
  34        if (flavor >= RPC_AUTH_MAXFLAVOR)
  35                return RPC_AUTH_GSS;
  36        return flavor;
  37}
  38
  39int
  40rpcauth_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}
  55EXPORT_SYMBOL_GPL(rpcauth_register);
  56
  57int
  58rpcauth_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}
  73EXPORT_SYMBOL_GPL(rpcauth_unregister);
  74
  75struct rpc_auth *
  76rpcauth_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
 103out:
 104        return auth;
 105}
 106EXPORT_SYMBOL_GPL(rpcauth_create);
 107
 108void
 109rpcauth_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
 116static DEFINE_SPINLOCK(rpc_credcache_lock);
 117
 118static void
 119rpcauth_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
 126static void
 127rpcauth_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 */
 141int
 142rpcauth_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}
 156EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
 157
 158/*
 159 * Destroy a list of credentials
 160 */
 161static inline
 162void 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 */
 177void
 178rpcauth_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 */
 208void
 209rpcauth_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}
 219EXPORT_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 */
 227static int
 228rpcauth_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_open(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 */
 264static int
 265rpcauth_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 */
 283struct rpc_cred *
 284rpcauth_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);
 334found:
 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);
 345out:
 346        return cred;
 347}
 348EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
 349
 350struct rpc_cred *
 351rpcauth_lookupcred(struct rpc_auth *auth, int flags)
 352{
 353        struct auth_cred acred;
 354        struct rpc_cred *ret;
 355        const struct cred *cred = current_cred();
 356
 357        dprintk("RPC:       looking up %s cred\n",
 358                auth->au_ops->au_name);
 359
 360        memset(&acred, 0, sizeof(acred));
 361        acred.uid = cred->fsuid;
 362        acred.gid = cred->fsgid;
 363        acred.group_info = get_group_info(((struct cred *)cred)->group_info);
 364
 365        ret = auth->au_ops->lookup_cred(auth, &acred, flags);
 366        put_group_info(acred.group_info);
 367        return ret;
 368}
 369
 370void
 371rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
 372                  struct rpc_auth *auth, const struct rpc_credops *ops)
 373{
 374        INIT_HLIST_NODE(&cred->cr_hash);
 375        INIT_LIST_HEAD(&cred->cr_lru);
 376        atomic_set(&cred->cr_count, 1);
 377        cred->cr_auth = auth;
 378        cred->cr_ops = ops;
 379        cred->cr_expire = jiffies;
 380#ifdef RPC_DEBUG
 381        cred->cr_magic = RPCAUTH_CRED_MAGIC;
 382#endif
 383        cred->cr_uid = acred->uid;
 384}
 385EXPORT_SYMBOL_GPL(rpcauth_init_cred);
 386
 387void
 388rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred, int lookupflags)
 389{
 390        task->tk_msg.rpc_cred = get_rpccred(cred);
 391        dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
 392                        cred->cr_auth->au_ops->au_name, cred);
 393}
 394EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
 395
 396static void
 397rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
 398{
 399        struct rpc_auth *auth = task->tk_client->cl_auth;
 400        struct auth_cred acred = {
 401                .uid = 0,
 402                .gid = 0,
 403        };
 404        struct rpc_cred *ret;
 405
 406        dprintk("RPC: %5u looking up %s cred\n",
 407                task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
 408        ret = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
 409        if (!IS_ERR(ret))
 410                task->tk_msg.rpc_cred = ret;
 411        else
 412                task->tk_status = PTR_ERR(ret);
 413}
 414
 415static void
 416rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
 417{
 418        struct rpc_auth *auth = task->tk_client->cl_auth;
 419        struct rpc_cred *ret;
 420
 421        dprintk("RPC: %5u looking up %s cred\n",
 422                task->tk_pid, auth->au_ops->au_name);
 423        ret = rpcauth_lookupcred(auth, lookupflags);
 424        if (!IS_ERR(ret))
 425                task->tk_msg.rpc_cred = ret;
 426        else
 427                task->tk_status = PTR_ERR(ret);
 428}
 429
 430void
 431rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
 432{
 433        int lookupflags = 0;
 434
 435        if (flags & RPC_TASK_ASYNC)
 436                lookupflags |= RPCAUTH_LOOKUP_NEW;
 437        if (cred != NULL)
 438                cred->cr_ops->crbind(task, cred, lookupflags);
 439        else if (flags & RPC_TASK_ROOTCREDS)
 440                rpcauth_bind_root_cred(task, lookupflags);
 441        else
 442                rpcauth_bind_new_cred(task, lookupflags);
 443}
 444
 445void
 446put_rpccred(struct rpc_cred *cred)
 447{
 448        /* Fast path for unhashed credentials */
 449        if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
 450                goto need_lock;
 451
 452        if (!atomic_dec_and_test(&cred->cr_count))
 453                return;
 454        goto out_destroy;
 455need_lock:
 456        if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
 457                return;
 458        if (!list_empty(&cred->cr_lru)) {
 459                number_cred_unused--;
 460                list_del_init(&cred->cr_lru);
 461        }
 462        if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
 463                rpcauth_unhash_cred(cred);
 464        if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
 465                cred->cr_expire = jiffies;
 466                list_add_tail(&cred->cr_lru, &cred_unused);
 467                number_cred_unused++;
 468                spin_unlock(&rpc_credcache_lock);
 469                return;
 470        }
 471        spin_unlock(&rpc_credcache_lock);
 472out_destroy:
 473        cred->cr_ops->crdestroy(cred);
 474}
 475EXPORT_SYMBOL_GPL(put_rpccred);
 476
 477void
 478rpcauth_unbindcred(struct rpc_task *task)
 479{
 480        struct rpc_cred *cred = task->tk_msg.rpc_cred;
 481
 482        dprintk("RPC: %5u releasing %s cred %p\n",
 483                task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 484
 485        put_rpccred(cred);
 486        task->tk_msg.rpc_cred = NULL;
 487}
 488
 489__be32 *
 490rpcauth_marshcred(struct rpc_task *task, __be32 *p)
 491{
 492        struct rpc_cred *cred = task->tk_msg.rpc_cred;
 493
 494        dprintk("RPC: %5u marshaling %s cred %p\n",
 495                task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 496
 497        return cred->cr_ops->crmarshal(task, p);
 498}
 499
 500__be32 *
 501rpcauth_checkverf(struct rpc_task *task, __be32 *p)
 502{
 503        struct rpc_cred *cred = task->tk_msg.rpc_cred;
 504
 505        dprintk("RPC: %5u validating %s cred %p\n",
 506                task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 507
 508        return cred->cr_ops->crvalidate(task, p);
 509}
 510
 511int
 512rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
 513                __be32 *data, void *obj)
 514{
 515        struct rpc_cred *cred = task->tk_msg.rpc_cred;
 516
 517        dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
 518                        task->tk_pid, cred->cr_ops->cr_name, cred);
 519        if (cred->cr_ops->crwrap_req)
 520                return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
 521        /* By default, we encode the arguments normally. */
 522        return encode(rqstp, data, obj);
 523}
 524
 525int
 526rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
 527                __be32 *data, void *obj)
 528{
 529        struct rpc_cred *cred = task->tk_msg.rpc_cred;
 530
 531        dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
 532                        task->tk_pid, cred->cr_ops->cr_name, cred);
 533        if (cred->cr_ops->crunwrap_resp)
 534                return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
 535                                                   data, obj);
 536        /* By default, we decode the arguments normally. */
 537        return decode(rqstp, data, obj);
 538}
 539
 540int
 541rpcauth_refreshcred(struct rpc_task *task)
 542{
 543        struct rpc_cred *cred = task->tk_msg.rpc_cred;
 544        int err;
 545
 546        dprintk("RPC: %5u refreshing %s cred %p\n",
 547                task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 548
 549        err = cred->cr_ops->crrefresh(task);
 550        if (err < 0)
 551                task->tk_status = err;
 552        return err;
 553}
 554
 555void
 556rpcauth_invalcred(struct rpc_task *task)
 557{
 558        struct rpc_cred *cred = task->tk_msg.rpc_cred;
 559
 560        dprintk("RPC: %5u invalidating %s cred %p\n",
 561                task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
 562        if (cred)
 563                clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
 564}
 565
 566int
 567rpcauth_uptodatecred(struct rpc_task *task)
 568{
 569        struct rpc_cred *cred = task->tk_msg.rpc_cred;
 570
 571        return cred == NULL ||
 572                test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
 573}
 574
 575static struct shrinker rpc_cred_shrinker = {
 576        .shrink = rpcauth_cache_shrinker,
 577        .seeks = DEFAULT_SEEKS,
 578};
 579
 580void __init rpcauth_init_module(void)
 581{
 582        rpc_init_authunix();
 583        rpc_init_generic_auth();
 584        register_shrinker(&rpc_cred_shrinker);
 585}
 586
 587void __exit rpcauth_remove_module(void)
 588{
 589        unregister_shrinker(&rpc_cred_shrinker);
 590}
 591