linux/ipc/util.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * linux/ipc/util.c
   4 * Copyright (C) 1992 Krishna Balasubramanian
   5 *
   6 * Sep 1997 - Call suser() last after "normal" permission checks so we
   7 *            get BSD style process accounting right.
   8 *            Occurs in several places in the IPC code.
   9 *            Chris Evans, <chris@ferret.lmh.ox.ac.uk>
  10 * Nov 1999 - ipc helper functions, unified SMP locking
  11 *            Manfred Spraul <manfred@colorfullife.com>
  12 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
  13 *            Mingming Cao <cmm@us.ibm.com>
  14 * Mar 2006 - support for audit of ipc object properties
  15 *            Dustin Kirkland <dustin.kirkland@us.ibm.com>
  16 * Jun 2006 - namespaces ssupport
  17 *            OpenVZ, SWsoft Inc.
  18 *            Pavel Emelianov <xemul@openvz.org>
  19 *
  20 * General sysv ipc locking scheme:
  21 *      rcu_read_lock()
  22 *          obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
  23 *          tree.
  24 *          - perform initial checks (capabilities, auditing and permission,
  25 *            etc).
  26 *          - perform read-only operations, such as INFO command, that
  27 *            do not demand atomicity
  28 *            acquire the ipc lock (kern_ipc_perm.lock) through
  29 *            ipc_lock_object()
  30 *              - perform read-only operations that demand atomicity,
  31 *                such as STAT command.
  32 *              - perform data updates, such as SET, RMID commands and
  33 *                mechanism-specific operations (semop/semtimedop,
  34 *                msgsnd/msgrcv, shmat/shmdt).
  35 *          drop the ipc lock, through ipc_unlock_object().
  36 *      rcu_read_unlock()
  37 *
  38 *  The ids->rwsem must be taken when:
  39 *      - creating, removing and iterating the existing entries in ipc
  40 *        identifier sets.
  41 *      - iterating through files under /proc/sysvipc/
  42 *
  43 *  Note that sems have a special fast path that avoids kern_ipc_perm.lock -
  44 *  see sem_lock().
  45 */
  46
  47#include <linux/mm.h>
  48#include <linux/shm.h>
  49#include <linux/init.h>
  50#include <linux/msg.h>
  51#include <linux/vmalloc.h>
  52#include <linux/slab.h>
  53#include <linux/notifier.h>
  54#include <linux/capability.h>
  55#include <linux/highuid.h>
  56#include <linux/security.h>
  57#include <linux/rcupdate.h>
  58#include <linux/workqueue.h>
  59#include <linux/seq_file.h>
  60#include <linux/proc_fs.h>
  61#include <linux/audit.h>
  62#include <linux/nsproxy.h>
  63#include <linux/rwsem.h>
  64#include <linux/memory.h>
  65#include <linux/ipc_namespace.h>
  66#include <linux/rhashtable.h>
  67#include <linux/log2.h>
  68
  69#include <asm/unistd.h>
  70
  71#include "util.h"
  72
  73struct ipc_proc_iface {
  74        const char *path;
  75        const char *header;
  76        int ids;
  77        int (*show)(struct seq_file *, void *);
  78};
  79
  80/**
  81 * ipc_init - initialise ipc subsystem
  82 *
  83 * The various sysv ipc resources (semaphores, messages and shared
  84 * memory) are initialised.
  85 *
  86 * A callback routine is registered into the memory hotplug notifier
  87 * chain: since msgmni scales to lowmem this callback routine will be
  88 * called upon successful memory add / remove to recompute msmgni.
  89 */
  90static int __init ipc_init(void)
  91{
  92        proc_mkdir("sysvipc", NULL);
  93        sem_init();
  94        msg_init();
  95        shm_init();
  96
  97        return 0;
  98}
  99device_initcall(ipc_init);
 100
 101static const struct rhashtable_params ipc_kht_params = {
 102        .head_offset            = offsetof(struct kern_ipc_perm, khtnode),
 103        .key_offset             = offsetof(struct kern_ipc_perm, key),
 104        .key_len                = sizeof_field(struct kern_ipc_perm, key),
 105        .automatic_shrinking    = true,
 106};
 107
 108/**
 109 * ipc_init_ids - initialise ipc identifiers
 110 * @ids: ipc identifier set
 111 *
 112 * Set up the sequence range to use for the ipc identifier range (limited
 113 * below ipc_mni) then initialise the keys hashtable and ids idr.
 114 */
 115void ipc_init_ids(struct ipc_ids *ids)
 116{
 117        ids->in_use = 0;
 118        ids->seq = 0;
 119        init_rwsem(&ids->rwsem);
 120        rhashtable_init(&ids->key_ht, &ipc_kht_params);
 121        idr_init(&ids->ipcs_idr);
 122        ids->max_idx = -1;
 123        ids->last_idx = -1;
 124#ifdef CONFIG_CHECKPOINT_RESTORE
 125        ids->next_id = -1;
 126#endif
 127}
 128
 129#ifdef CONFIG_PROC_FS
 130static const struct proc_ops sysvipc_proc_ops;
 131/**
 132 * ipc_init_proc_interface -  create a proc interface for sysipc types using a seq_file interface.
 133 * @path: Path in procfs
 134 * @header: Banner to be printed at the beginning of the file.
 135 * @ids: ipc id table to iterate.
 136 * @show: show routine.
 137 */
 138void __init ipc_init_proc_interface(const char *path, const char *header,
 139                int ids, int (*show)(struct seq_file *, void *))
 140{
 141        struct proc_dir_entry *pde;
 142        struct ipc_proc_iface *iface;
 143
 144        iface = kmalloc(sizeof(*iface), GFP_KERNEL);
 145        if (!iface)
 146                return;
 147        iface->path     = path;
 148        iface->header   = header;
 149        iface->ids      = ids;
 150        iface->show     = show;
 151
 152        pde = proc_create_data(path,
 153                               S_IRUGO,        /* world readable */
 154                               NULL,           /* parent dir */
 155                               &sysvipc_proc_ops,
 156                               iface);
 157        if (!pde)
 158                kfree(iface);
 159}
 160#endif
 161
 162/**
 163 * ipc_findkey  - find a key in an ipc identifier set
 164 * @ids: ipc identifier set
 165 * @key: key to find
 166 *
 167 * Returns the locked pointer to the ipc structure if found or NULL
 168 * otherwise. If key is found ipc points to the owning ipc structure
 169 *
 170 * Called with writer ipc_ids.rwsem held.
 171 */
 172static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
 173{
 174        struct kern_ipc_perm *ipcp;
 175
 176        ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
 177                                              ipc_kht_params);
 178        if (!ipcp)
 179                return NULL;
 180
 181        rcu_read_lock();
 182        ipc_lock_object(ipcp);
 183        return ipcp;
 184}
 185
 186/*
 187 * Insert new IPC object into idr tree, and set sequence number and id
 188 * in the correct order.
 189 * Especially:
 190 * - the sequence number must be set before inserting the object into the idr,
 191 *   because the sequence number is accessed without a lock.
 192 * - the id can/must be set after inserting the object into the idr.
 193 *   All accesses must be done after getting kern_ipc_perm.lock.
 194 *
 195 * The caller must own kern_ipc_perm.lock.of the new object.
 196 * On error, the function returns a (negative) error code.
 197 *
 198 * To conserve sequence number space, especially with extended ipc_mni,
 199 * the sequence number is incremented only when the returned ID is less than
 200 * the last one.
 201 */
 202static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new)
 203{
 204        int idx, next_id = -1;
 205
 206#ifdef CONFIG_CHECKPOINT_RESTORE
 207        next_id = ids->next_id;
 208        ids->next_id = -1;
 209#endif
 210
 211        /*
 212         * As soon as a new object is inserted into the idr,
 213         * ipc_obtain_object_idr() or ipc_obtain_object_check() can find it,
 214         * and the lockless preparations for ipc operations can start.
 215         * This means especially: permission checks, audit calls, allocation
 216         * of undo structures, ...
 217         *
 218         * Thus the object must be fully initialized, and if something fails,
 219         * then the full tear-down sequence must be followed.
 220         * (i.e.: set new->deleted, reduce refcount, call_rcu())
 221         */
 222
 223        if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */
 224                int max_idx;
 225
 226                max_idx = max(ids->in_use*3/2, ipc_min_cycle);
 227                max_idx = min(max_idx, ipc_mni);
 228
 229                /* allocate the idx, with a NULL struct kern_ipc_perm */
 230                idx = idr_alloc_cyclic(&ids->ipcs_idr, NULL, 0, max_idx,
 231                                        GFP_NOWAIT);
 232
 233                if (idx >= 0) {
 234                        /*
 235                         * idx got allocated successfully.
 236                         * Now calculate the sequence number and set the
 237                         * pointer for real.
 238                         */
 239                        if (idx <= ids->last_idx) {
 240                                ids->seq++;
 241                                if (ids->seq >= ipcid_seq_max())
 242                                        ids->seq = 0;
 243                        }
 244                        ids->last_idx = idx;
 245
 246                        new->seq = ids->seq;
 247                        /* no need for smp_wmb(), this is done
 248                         * inside idr_replace, as part of
 249                         * rcu_assign_pointer
 250                         */
 251                        idr_replace(&ids->ipcs_idr, new, idx);
 252                }
 253        } else {
 254                new->seq = ipcid_to_seqx(next_id);
 255                idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id),
 256                                0, GFP_NOWAIT);
 257        }
 258        if (idx >= 0)
 259                new->id = (new->seq << ipcmni_seq_shift()) + idx;
 260        return idx;
 261}
 262
 263/**
 264 * ipc_addid - add an ipc identifier
 265 * @ids: ipc identifier set
 266 * @new: new ipc permission set
 267 * @limit: limit for the number of used ids
 268 *
 269 * Add an entry 'new' to the ipc ids idr. The permissions object is
 270 * initialised and the first free entry is set up and the index assigned
 271 * is returned. The 'new' entry is returned in a locked state on success.
 272 *
 273 * On failure the entry is not locked and a negative err-code is returned.
 274 * The caller must use ipc_rcu_putref() to free the identifier.
 275 *
 276 * Called with writer ipc_ids.rwsem held.
 277 */
 278int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
 279{
 280        kuid_t euid;
 281        kgid_t egid;
 282        int idx, err;
 283
 284        /* 1) Initialize the refcount so that ipc_rcu_putref works */
 285        refcount_set(&new->refcount, 1);
 286
 287        if (limit > ipc_mni)
 288                limit = ipc_mni;
 289
 290        if (ids->in_use >= limit)
 291                return -ENOSPC;
 292
 293        idr_preload(GFP_KERNEL);
 294
 295        spin_lock_init(&new->lock);
 296        rcu_read_lock();
 297        spin_lock(&new->lock);
 298
 299        current_euid_egid(&euid, &egid);
 300        new->cuid = new->uid = euid;
 301        new->gid = new->cgid = egid;
 302
 303        new->deleted = false;
 304
 305        idx = ipc_idr_alloc(ids, new);
 306        idr_preload_end();
 307
 308        if (idx >= 0 && new->key != IPC_PRIVATE) {
 309                err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
 310                                             ipc_kht_params);
 311                if (err < 0) {
 312                        idr_remove(&ids->ipcs_idr, idx);
 313                        idx = err;
 314                }
 315        }
 316        if (idx < 0) {
 317                new->deleted = true;
 318                spin_unlock(&new->lock);
 319                rcu_read_unlock();
 320                return idx;
 321        }
 322
 323        ids->in_use++;
 324        if (idx > ids->max_idx)
 325                ids->max_idx = idx;
 326        return idx;
 327}
 328
 329/**
 330 * ipcget_new - create a new ipc object
 331 * @ns: ipc namespace
 332 * @ids: ipc identifier set
 333 * @ops: the actual creation routine to call
 334 * @params: its parameters
 335 *
 336 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
 337 * when the key is IPC_PRIVATE.
 338 */
 339static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
 340                const struct ipc_ops *ops, struct ipc_params *params)
 341{
 342        int err;
 343
 344        down_write(&ids->rwsem);
 345        err = ops->getnew(ns, params);
 346        up_write(&ids->rwsem);
 347        return err;
 348}
 349
 350/**
 351 * ipc_check_perms - check security and permissions for an ipc object
 352 * @ns: ipc namespace
 353 * @ipcp: ipc permission set
 354 * @ops: the actual security routine to call
 355 * @params: its parameters
 356 *
 357 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
 358 * when the key is not IPC_PRIVATE and that key already exists in the
 359 * ds IDR.
 360 *
 361 * On success, the ipc id is returned.
 362 *
 363 * It is called with ipc_ids.rwsem and ipcp->lock held.
 364 */
 365static int ipc_check_perms(struct ipc_namespace *ns,
 366                           struct kern_ipc_perm *ipcp,
 367                           const struct ipc_ops *ops,
 368                           struct ipc_params *params)
 369{
 370        int err;
 371
 372        if (ipcperms(ns, ipcp, params->flg))
 373                err = -EACCES;
 374        else {
 375                err = ops->associate(ipcp, params->flg);
 376                if (!err)
 377                        err = ipcp->id;
 378        }
 379
 380        return err;
 381}
 382
 383/**
 384 * ipcget_public - get an ipc object or create a new one
 385 * @ns: ipc namespace
 386 * @ids: ipc identifier set
 387 * @ops: the actual creation routine to call
 388 * @params: its parameters
 389 *
 390 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
 391 * when the key is not IPC_PRIVATE.
 392 * It adds a new entry if the key is not found and does some permission
 393 * / security checkings if the key is found.
 394 *
 395 * On success, the ipc id is returned.
 396 */
 397static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
 398                const struct ipc_ops *ops, struct ipc_params *params)
 399{
 400        struct kern_ipc_perm *ipcp;
 401        int flg = params->flg;
 402        int err;
 403
 404        /*
 405         * Take the lock as a writer since we are potentially going to add
 406         * a new entry + read locks are not "upgradable"
 407         */
 408        down_write(&ids->rwsem);
 409        ipcp = ipc_findkey(ids, params->key);
 410        if (ipcp == NULL) {
 411                /* key not used */
 412                if (!(flg & IPC_CREAT))
 413                        err = -ENOENT;
 414                else
 415                        err = ops->getnew(ns, params);
 416        } else {
 417                /* ipc object has been locked by ipc_findkey() */
 418
 419                if (flg & IPC_CREAT && flg & IPC_EXCL)
 420                        err = -EEXIST;
 421                else {
 422                        err = 0;
 423                        if (ops->more_checks)
 424                                err = ops->more_checks(ipcp, params);
 425                        if (!err)
 426                                /*
 427                                 * ipc_check_perms returns the IPC id on
 428                                 * success
 429                                 */
 430                                err = ipc_check_perms(ns, ipcp, ops, params);
 431                }
 432                ipc_unlock(ipcp);
 433        }
 434        up_write(&ids->rwsem);
 435
 436        return err;
 437}
 438
 439/**
 440 * ipc_kht_remove - remove an ipc from the key hashtable
 441 * @ids: ipc identifier set
 442 * @ipcp: ipc perm structure containing the key to remove
 443 *
 444 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
 445 * before this function is called, and remain locked on the exit.
 446 */
 447static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 448{
 449        if (ipcp->key != IPC_PRIVATE)
 450                WARN_ON_ONCE(rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
 451                                       ipc_kht_params));
 452}
 453
 454/**
 455 * ipc_search_maxidx - search for the highest assigned index
 456 * @ids: ipc identifier set
 457 * @limit: known upper limit for highest assigned index
 458 *
 459 * The function determines the highest assigned index in @ids. It is intended
 460 * to be called when ids->max_idx needs to be updated.
 461 * Updating ids->max_idx is necessary when the current highest index ipc
 462 * object is deleted.
 463 * If no ipc object is allocated, then -1 is returned.
 464 *
 465 * ipc_ids.rwsem needs to be held by the caller.
 466 */
 467static int ipc_search_maxidx(struct ipc_ids *ids, int limit)
 468{
 469        int tmpidx;
 470        int i;
 471        int retval;
 472
 473        i = ilog2(limit+1);
 474
 475        retval = 0;
 476        for (; i >= 0; i--) {
 477                tmpidx = retval | (1<<i);
 478                /*
 479                 * "0" is a possible index value, thus search using
 480                 * e.g. 15,7,3,1,0 instead of 16,8,4,2,1.
 481                 */
 482                tmpidx = tmpidx-1;
 483                if (idr_get_next(&ids->ipcs_idr, &tmpidx))
 484                        retval |= (1<<i);
 485        }
 486        return retval - 1;
 487}
 488
 489/**
 490 * ipc_rmid - remove an ipc identifier
 491 * @ids: ipc identifier set
 492 * @ipcp: ipc perm structure containing the identifier to remove
 493 *
 494 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
 495 * before this function is called, and remain locked on the exit.
 496 */
 497void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 498{
 499        int idx = ipcid_to_idx(ipcp->id);
 500
 501        WARN_ON_ONCE(idr_remove(&ids->ipcs_idr, idx) != ipcp);
 502        ipc_kht_remove(ids, ipcp);
 503        ids->in_use--;
 504        ipcp->deleted = true;
 505
 506        if (unlikely(idx == ids->max_idx)) {
 507                idx = ids->max_idx-1;
 508                if (idx >= 0)
 509                        idx = ipc_search_maxidx(ids, idx);
 510                ids->max_idx = idx;
 511        }
 512}
 513
 514/**
 515 * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
 516 * @ids: ipc identifier set
 517 * @ipcp: ipc perm structure containing the key to modify
 518 *
 519 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
 520 * before this function is called, and remain locked on the exit.
 521 */
 522void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 523{
 524        ipc_kht_remove(ids, ipcp);
 525        ipcp->key = IPC_PRIVATE;
 526}
 527
 528bool ipc_rcu_getref(struct kern_ipc_perm *ptr)
 529{
 530        return refcount_inc_not_zero(&ptr->refcount);
 531}
 532
 533void ipc_rcu_putref(struct kern_ipc_perm *ptr,
 534                        void (*func)(struct rcu_head *head))
 535{
 536        if (!refcount_dec_and_test(&ptr->refcount))
 537                return;
 538
 539        call_rcu(&ptr->rcu, func);
 540}
 541
 542/**
 543 * ipcperms - check ipc permissions
 544 * @ns: ipc namespace
 545 * @ipcp: ipc permission set
 546 * @flag: desired permission set
 547 *
 548 * Check user, group, other permissions for access
 549 * to ipc resources. return 0 if allowed
 550 *
 551 * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
 552 */
 553int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
 554{
 555        kuid_t euid = current_euid();
 556        int requested_mode, granted_mode;
 557
 558        audit_ipc_obj(ipcp);
 559        requested_mode = (flag >> 6) | (flag >> 3) | flag;
 560        granted_mode = ipcp->mode;
 561        if (uid_eq(euid, ipcp->cuid) ||
 562            uid_eq(euid, ipcp->uid))
 563                granted_mode >>= 6;
 564        else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
 565                granted_mode >>= 3;
 566        /* is there some bit set in requested_mode but not in granted_mode? */
 567        if ((requested_mode & ~granted_mode & 0007) &&
 568            !ns_capable(ns->user_ns, CAP_IPC_OWNER))
 569                return -1;
 570
 571        return security_ipc_permission(ipcp, flag);
 572}
 573
 574/*
 575 * Functions to convert between the kern_ipc_perm structure and the
 576 * old/new ipc_perm structures
 577 */
 578
 579/**
 580 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
 581 * @in: kernel permissions
 582 * @out: new style ipc permissions
 583 *
 584 * Turn the kernel object @in into a set of permissions descriptions
 585 * for returning to userspace (@out).
 586 */
 587void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
 588{
 589        out->key        = in->key;
 590        out->uid        = from_kuid_munged(current_user_ns(), in->uid);
 591        out->gid        = from_kgid_munged(current_user_ns(), in->gid);
 592        out->cuid       = from_kuid_munged(current_user_ns(), in->cuid);
 593        out->cgid       = from_kgid_munged(current_user_ns(), in->cgid);
 594        out->mode       = in->mode;
 595        out->seq        = in->seq;
 596}
 597
 598/**
 599 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
 600 * @in: new style ipc permissions
 601 * @out: old style ipc permissions
 602 *
 603 * Turn the new style permissions object @in into a compatibility
 604 * object and store it into the @out pointer.
 605 */
 606void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
 607{
 608        out->key        = in->key;
 609        SET_UID(out->uid, in->uid);
 610        SET_GID(out->gid, in->gid);
 611        SET_UID(out->cuid, in->cuid);
 612        SET_GID(out->cgid, in->cgid);
 613        out->mode       = in->mode;
 614        out->seq        = in->seq;
 615}
 616
 617/**
 618 * ipc_obtain_object_idr
 619 * @ids: ipc identifier set
 620 * @id: ipc id to look for
 621 *
 622 * Look for an id in the ipc ids idr and return associated ipc object.
 623 *
 624 * Call inside the RCU critical section.
 625 * The ipc object is *not* locked on exit.
 626 */
 627struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
 628{
 629        struct kern_ipc_perm *out;
 630        int idx = ipcid_to_idx(id);
 631
 632        out = idr_find(&ids->ipcs_idr, idx);
 633        if (!out)
 634                return ERR_PTR(-EINVAL);
 635
 636        return out;
 637}
 638
 639/**
 640 * ipc_obtain_object_check
 641 * @ids: ipc identifier set
 642 * @id: ipc id to look for
 643 *
 644 * Similar to ipc_obtain_object_idr() but also checks the ipc object
 645 * sequence number.
 646 *
 647 * Call inside the RCU critical section.
 648 * The ipc object is *not* locked on exit.
 649 */
 650struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
 651{
 652        struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
 653
 654        if (IS_ERR(out))
 655                goto out;
 656
 657        if (ipc_checkid(out, id))
 658                return ERR_PTR(-EINVAL);
 659out:
 660        return out;
 661}
 662
 663/**
 664 * ipcget - Common sys_*get() code
 665 * @ns: namespace
 666 * @ids: ipc identifier set
 667 * @ops: operations to be called on ipc object creation, permission checks
 668 *       and further checks
 669 * @params: the parameters needed by the previous operations.
 670 *
 671 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 672 */
 673int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 674                        const struct ipc_ops *ops, struct ipc_params *params)
 675{
 676        if (params->key == IPC_PRIVATE)
 677                return ipcget_new(ns, ids, ops, params);
 678        else
 679                return ipcget_public(ns, ids, ops, params);
 680}
 681
 682/**
 683 * ipc_update_perm - update the permissions of an ipc object
 684 * @in:  the permission given as input.
 685 * @out: the permission of the ipc to set.
 686 */
 687int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 688{
 689        kuid_t uid = make_kuid(current_user_ns(), in->uid);
 690        kgid_t gid = make_kgid(current_user_ns(), in->gid);
 691        if (!uid_valid(uid) || !gid_valid(gid))
 692                return -EINVAL;
 693
 694        out->uid = uid;
 695        out->gid = gid;
 696        out->mode = (out->mode & ~S_IRWXUGO)
 697                | (in->mode & S_IRWXUGO);
 698
 699        return 0;
 700}
 701
 702/**
 703 * ipcctl_obtain_check - retrieve an ipc object and check permissions
 704 * @ns:  ipc namespace
 705 * @ids:  the table of ids where to look for the ipc
 706 * @id:   the id of the ipc to retrieve
 707 * @cmd:  the cmd to check
 708 * @perm: the permission to set
 709 * @extra_perm: one extra permission parameter used by msq
 710 *
 711 * This function does some common audit and permissions check for some IPC_XXX
 712 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
 713 *
 714 * It:
 715 *   - retrieves the ipc object with the given id in the given table.
 716 *   - performs some audit and permission check, depending on the given cmd
 717 *   - returns a pointer to the ipc object or otherwise, the corresponding
 718 *     error.
 719 *
 720 * Call holding the both the rwsem and the rcu read lock.
 721 */
 722struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
 723                                        struct ipc_ids *ids, int id, int cmd,
 724                                        struct ipc64_perm *perm, int extra_perm)
 725{
 726        kuid_t euid;
 727        int err = -EPERM;
 728        struct kern_ipc_perm *ipcp;
 729
 730        ipcp = ipc_obtain_object_check(ids, id);
 731        if (IS_ERR(ipcp)) {
 732                err = PTR_ERR(ipcp);
 733                goto err;
 734        }
 735
 736        audit_ipc_obj(ipcp);
 737        if (cmd == IPC_SET)
 738                audit_ipc_set_perm(extra_perm, perm->uid,
 739                                   perm->gid, perm->mode);
 740
 741        euid = current_euid();
 742        if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
 743            ns_capable(ns->user_ns, CAP_SYS_ADMIN))
 744                return ipcp; /* successful lookup */
 745err:
 746        return ERR_PTR(err);
 747}
 748
 749#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 750
 751
 752/**
 753 * ipc_parse_version - ipc call version
 754 * @cmd: pointer to command
 755 *
 756 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
 757 * The @cmd value is turned from an encoding command and version into
 758 * just the command code.
 759 */
 760int ipc_parse_version(int *cmd)
 761{
 762        if (*cmd & IPC_64) {
 763                *cmd ^= IPC_64;
 764                return IPC_64;
 765        } else {
 766                return IPC_OLD;
 767        }
 768}
 769
 770#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
 771
 772#ifdef CONFIG_PROC_FS
 773struct ipc_proc_iter {
 774        struct ipc_namespace *ns;
 775        struct pid_namespace *pid_ns;
 776        struct ipc_proc_iface *iface;
 777};
 778
 779struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
 780{
 781        struct ipc_proc_iter *iter = s->private;
 782        return iter->pid_ns;
 783}
 784
 785/*
 786 * This routine locks the ipc structure found at least at position pos.
 787 */
 788static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
 789                                              loff_t *new_pos)
 790{
 791        struct kern_ipc_perm *ipc = NULL;
 792        int max_idx = ipc_get_maxidx(ids);
 793
 794        if (max_idx == -1 || pos > max_idx)
 795                goto out;
 796
 797        for (; pos <= max_idx; pos++) {
 798                ipc = idr_find(&ids->ipcs_idr, pos);
 799                if (ipc != NULL) {
 800                        rcu_read_lock();
 801                        ipc_lock_object(ipc);
 802                        break;
 803                }
 804        }
 805out:
 806        *new_pos = pos + 1;
 807        return ipc;
 808}
 809
 810static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 811{
 812        struct ipc_proc_iter *iter = s->private;
 813        struct ipc_proc_iface *iface = iter->iface;
 814        struct kern_ipc_perm *ipc = it;
 815
 816        /* If we had an ipc id locked before, unlock it */
 817        if (ipc && ipc != SEQ_START_TOKEN)
 818                ipc_unlock(ipc);
 819
 820        return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
 821}
 822
 823/*
 824 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
 825 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
 826 */
 827static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 828{
 829        struct ipc_proc_iter *iter = s->private;
 830        struct ipc_proc_iface *iface = iter->iface;
 831        struct ipc_ids *ids;
 832
 833        ids = &iter->ns->ids[iface->ids];
 834
 835        /*
 836         * Take the lock - this will be released by the corresponding
 837         * call to stop().
 838         */
 839        down_read(&ids->rwsem);
 840
 841        /* pos < 0 is invalid */
 842        if (*pos < 0)
 843                return NULL;
 844
 845        /* pos == 0 means header */
 846        if (*pos == 0)
 847                return SEQ_START_TOKEN;
 848
 849        /* Find the (pos-1)th ipc */
 850        return sysvipc_find_ipc(ids, *pos - 1, pos);
 851}
 852
 853static void sysvipc_proc_stop(struct seq_file *s, void *it)
 854{
 855        struct kern_ipc_perm *ipc = it;
 856        struct ipc_proc_iter *iter = s->private;
 857        struct ipc_proc_iface *iface = iter->iface;
 858        struct ipc_ids *ids;
 859
 860        /* If we had a locked structure, release it */
 861        if (ipc && ipc != SEQ_START_TOKEN)
 862                ipc_unlock(ipc);
 863
 864        ids = &iter->ns->ids[iface->ids];
 865        /* Release the lock we took in start() */
 866        up_read(&ids->rwsem);
 867}
 868
 869static int sysvipc_proc_show(struct seq_file *s, void *it)
 870{
 871        struct ipc_proc_iter *iter = s->private;
 872        struct ipc_proc_iface *iface = iter->iface;
 873
 874        if (it == SEQ_START_TOKEN) {
 875                seq_puts(s, iface->header);
 876                return 0;
 877        }
 878
 879        return iface->show(s, it);
 880}
 881
 882static const struct seq_operations sysvipc_proc_seqops = {
 883        .start = sysvipc_proc_start,
 884        .stop  = sysvipc_proc_stop,
 885        .next  = sysvipc_proc_next,
 886        .show  = sysvipc_proc_show,
 887};
 888
 889static int sysvipc_proc_open(struct inode *inode, struct file *file)
 890{
 891        struct ipc_proc_iter *iter;
 892
 893        iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
 894        if (!iter)
 895                return -ENOMEM;
 896
 897        iter->iface = pde_data(inode);
 898        iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
 899        iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
 900
 901        return 0;
 902}
 903
 904static int sysvipc_proc_release(struct inode *inode, struct file *file)
 905{
 906        struct seq_file *seq = file->private_data;
 907        struct ipc_proc_iter *iter = seq->private;
 908        put_ipc_ns(iter->ns);
 909        put_pid_ns(iter->pid_ns);
 910        return seq_release_private(inode, file);
 911}
 912
 913static const struct proc_ops sysvipc_proc_ops = {
 914        .proc_flags     = PROC_ENTRY_PERMANENT,
 915        .proc_open      = sysvipc_proc_open,
 916        .proc_read      = seq_read,
 917        .proc_lseek     = seq_lseek,
 918        .proc_release   = sysvipc_proc_release,
 919};
 920#endif /* CONFIG_PROC_FS */
 921