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 * sysvipc_find_ipc - Find and lock the ipc structure based on seq pos 787 * @ids: ipc identifier set 788 * @pos: expected position 789 * 790 * The function finds an ipc structure, based on the sequence file 791 * position @pos. If there is no ipc structure at position @pos, then 792 * the successor is selected. 793 * If a structure is found, then it is locked (both rcu_read_lock() and 794 * ipc_lock_object()) and @pos is set to the position needed to locate 795 * the found ipc structure. 796 * If nothing is found (i.e. EOF), @pos is not modified. 797 * 798 * The function returns the found ipc structure, or NULL at EOF. 799 */ 800static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t *pos) 801{ 802 int tmpidx; 803 struct kern_ipc_perm *ipc; 804 805 /* convert from position to idr index -> "-1" */ 806 tmpidx = *pos - 1; 807 808 ipc = idr_get_next(&ids->ipcs_idr, &tmpidx); 809 if (ipc != NULL) { 810 rcu_read_lock(); 811 ipc_lock_object(ipc); 812 813 /* convert from idr index to position -> "+1" */ 814 *pos = tmpidx + 1; 815 } 816 return ipc; 817} 818 819static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) 820{ 821 struct ipc_proc_iter *iter = s->private; 822 struct ipc_proc_iface *iface = iter->iface; 823 struct kern_ipc_perm *ipc = it; 824 825 /* If we had an ipc id locked before, unlock it */ 826 if (ipc && ipc != SEQ_START_TOKEN) 827 ipc_unlock(ipc); 828 829 /* Next -> search for *pos+1 */ 830 (*pos)++; 831 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], pos); 832} 833 834/* 835 * File positions: pos 0 -> header, pos n -> ipc idx = n - 1. 836 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. 837 */ 838static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) 839{ 840 struct ipc_proc_iter *iter = s->private; 841 struct ipc_proc_iface *iface = iter->iface; 842 struct ipc_ids *ids; 843 844 ids = &iter->ns->ids[iface->ids]; 845 846 /* 847 * Take the lock - this will be released by the corresponding 848 * call to stop(). 849 */ 850 down_read(&ids->rwsem); 851 852 /* pos < 0 is invalid */ 853 if (*pos < 0) 854 return NULL; 855 856 /* pos == 0 means header */ 857 if (*pos == 0) 858 return SEQ_START_TOKEN; 859 860 /* Otherwise return the correct ipc structure */ 861 return sysvipc_find_ipc(ids, pos); 862} 863 864static void sysvipc_proc_stop(struct seq_file *s, void *it) 865{ 866 struct kern_ipc_perm *ipc = it; 867 struct ipc_proc_iter *iter = s->private; 868 struct ipc_proc_iface *iface = iter->iface; 869 struct ipc_ids *ids; 870 871 /* If we had a locked structure, release it */ 872 if (ipc && ipc != SEQ_START_TOKEN) 873 ipc_unlock(ipc); 874 875 ids = &iter->ns->ids[iface->ids]; 876 /* Release the lock we took in start() */ 877 up_read(&ids->rwsem); 878} 879 880static int sysvipc_proc_show(struct seq_file *s, void *it) 881{ 882 struct ipc_proc_iter *iter = s->private; 883 struct ipc_proc_iface *iface = iter->iface; 884 885 if (it == SEQ_START_TOKEN) { 886 seq_puts(s, iface->header); 887 return 0; 888 } 889 890 return iface->show(s, it); 891} 892 893static const struct seq_operations sysvipc_proc_seqops = { 894 .start = sysvipc_proc_start, 895 .stop = sysvipc_proc_stop, 896 .next = sysvipc_proc_next, 897 .show = sysvipc_proc_show, 898}; 899 900static int sysvipc_proc_open(struct inode *inode, struct file *file) 901{ 902 struct ipc_proc_iter *iter; 903 904 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter)); 905 if (!iter) 906 return -ENOMEM; 907 908 iter->iface = pde_data(inode); 909 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); 910 iter->pid_ns = get_pid_ns(task_active_pid_ns(current)); 911 912 return 0; 913} 914 915static int sysvipc_proc_release(struct inode *inode, struct file *file) 916{ 917 struct seq_file *seq = file->private_data; 918 struct ipc_proc_iter *iter = seq->private; 919 put_ipc_ns(iter->ns); 920 put_pid_ns(iter->pid_ns); 921 return seq_release_private(inode, file); 922} 923 924static const struct proc_ops sysvipc_proc_ops = { 925 .proc_flags = PROC_ENTRY_PERMANENT, 926 .proc_open = sysvipc_proc_open, 927 .proc_read = seq_read, 928 .proc_lseek = seq_lseek, 929 .proc_release = sysvipc_proc_release, 930}; 931#endif /* CONFIG_PROC_FS */ 932