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 STAT, INFO commands. 27 * acquire the ipc lock (kern_ipc_perm.lock) through 28 * ipc_lock_object() 29 * - perform data updates, such as SET, RMID commands and 30 * mechanism-specific operations (semop/semtimedop, 31 * msgsnd/msgrcv, shmat/shmdt). 32 * drop the ipc lock, through ipc_unlock_object(). 33 * rcu_read_unlock() 34 * 35 * The ids->rwsem must be taken when: 36 * - creating, removing and iterating the existing entries in ipc 37 * identifier sets. 38 * - iterating through files under /proc/sysvipc/ 39 * 40 * Note that sems have a special fast path that avoids kern_ipc_perm.lock - 41 * see sem_lock(). 42 */ 43 44 #include <linux/mm.h> 45 #include <linux/shm.h> 46 #include <linux/init.h> 47 #include <linux/msg.h> 48 #include <linux/vmalloc.h> 49 #include <linux/slab.h> 50 #include <linux/notifier.h> 51 #include <linux/capability.h> 52 #include <linux/highuid.h> 53 #include <linux/security.h> 54 #include <linux/rcupdate.h> 55 #include <linux/workqueue.h> 56 #include <linux/seq_file.h> 57 #include <linux/proc_fs.h> 58 #include <linux/audit.h> 59 #include <linux/nsproxy.h> 60 #include <linux/rwsem.h> 61 #include <linux/memory.h> 62 #include <linux/ipc_namespace.h> 63 64 #include <asm/unistd.h> 65 66 #include "util.h" 67 68 struct ipc_proc_iface { 69 const char *path; 70 const char *header; 71 int ids; 72 int (*show)(struct seq_file *, void *); 73 }; 74 75 /** 76 * ipc_init - initialise ipc subsystem 77 * 78 * The various sysv ipc resources (semaphores, messages and shared 79 * memory) are initialised. 80 * 81 * A callback routine is registered into the memory hotplug notifier 82 * chain: since msgmni scales to lowmem this callback routine will be 83 * called upon successful memory add / remove to recompute msmgni. 84 */ 85 static int __init ipc_init(void) 86 { 87 int err_sem, err_msg; 88 89 err_sem = sem_init(); 90 WARN(err_sem, "ipc: sysv sem_init failed: %d\n", err_sem); 91 err_msg = msg_init(); 92 WARN(err_msg, "ipc: sysv msg_init failed: %d\n", err_msg); 93 shm_init(); 94 95 return err_msg ? err_msg : err_sem; 96 } 97 device_initcall(ipc_init); 98 99 static const struct rhashtable_params ipc_kht_params = { 100 .head_offset = offsetof(struct kern_ipc_perm, khtnode), 101 .key_offset = offsetof(struct kern_ipc_perm, key), 102 .key_len = FIELD_SIZEOF(struct kern_ipc_perm, key), 103 .locks_mul = 1, 104 .automatic_shrinking = true, 105 }; 106 107 /** 108 * ipc_init_ids - initialise ipc identifiers 109 * @ids: ipc identifier set 110 * 111 * Set up the sequence range to use for the ipc identifier range (limited 112 * below IPCMNI) then initialise the keys hashtable and ids idr. 113 */ 114 int ipc_init_ids(struct ipc_ids *ids) 115 { 116 int err; 117 ids->in_use = 0; 118 ids->seq = 0; 119 ids->next_id = -1; 120 init_rwsem(&ids->rwsem); 121 err = rhashtable_init(&ids->key_ht, &ipc_kht_params); 122 if (err) 123 return err; 124 idr_init(&ids->ipcs_idr); 125 ids->tables_initialized = true; 126 return 0; 127 } 128 129 #ifdef CONFIG_PROC_FS 130 static const struct file_operations sysvipc_proc_fops; 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 */ 138 void __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_fops, 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 */ 172 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) 173 { 174 struct kern_ipc_perm *ipcp = NULL; 175 176 if (likely(ids->tables_initialized)) 177 ipcp = rhashtable_lookup_fast(&ids->key_ht, &key, 178 ipc_kht_params); 179 180 if (ipcp) { 181 rcu_read_lock(); 182 ipc_lock_object(ipcp); 183 return ipcp; 184 } 185 186 return NULL; 187 } 188 189 /** 190 * ipc_get_maxid - get the last assigned id 191 * @ids: ipc identifier set 192 * 193 * Called with ipc_ids.rwsem held. 194 */ 195 int ipc_get_maxid(struct ipc_ids *ids) 196 { 197 struct kern_ipc_perm *ipc; 198 int max_id = -1; 199 int total, id; 200 201 if (ids->in_use == 0) 202 return -1; 203 204 if (ids->in_use == IPCMNI) 205 return IPCMNI - 1; 206 207 /* Look for the last assigned id */ 208 total = 0; 209 for (id = 0; id < IPCMNI && total < ids->in_use; id++) { 210 ipc = idr_find(&ids->ipcs_idr, id); 211 if (ipc != NULL) { 212 max_id = id; 213 total++; 214 } 215 } 216 return max_id; 217 } 218 219 /** 220 * ipc_addid - add an ipc identifier 221 * @ids: ipc identifier set 222 * @new: new ipc permission set 223 * @size: limit for the number of used ids 224 * 225 * Add an entry 'new' to the ipc ids idr. The permissions object is 226 * initialised and the first free entry is set up and the id assigned 227 * is returned. The 'new' entry is returned in a locked state on success. 228 * On failure the entry is not locked and a negative err-code is returned. 229 * 230 * Called with writer ipc_ids.rwsem held. 231 */ 232 int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size) 233 { 234 kuid_t euid; 235 kgid_t egid; 236 int id, err; 237 int next_id = ids->next_id; 238 239 if (size > IPCMNI) 240 size = IPCMNI; 241 242 if (!ids->tables_initialized || ids->in_use >= size) 243 return -ENOSPC; 244 245 idr_preload(GFP_KERNEL); 246 247 refcount_set(&new->refcount, 1); 248 spin_lock_init(&new->lock); 249 new->deleted = false; 250 rcu_read_lock(); 251 spin_lock(&new->lock); 252 253 current_euid_egid(&euid, &egid); 254 new->cuid = new->uid = euid; 255 new->gid = new->cgid = egid; 256 257 id = idr_alloc(&ids->ipcs_idr, new, 258 (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0, 259 GFP_NOWAIT); 260 idr_preload_end(); 261 262 if (id >= 0 && new->key != IPC_PRIVATE) { 263 err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode, 264 ipc_kht_params); 265 if (err < 0) { 266 idr_remove(&ids->ipcs_idr, id); 267 id = err; 268 } 269 } 270 if (id < 0) { 271 spin_unlock(&new->lock); 272 rcu_read_unlock(); 273 return id; 274 } 275 276 ids->in_use++; 277 278 if (next_id < 0) { 279 new->seq = ids->seq++; 280 if (ids->seq > IPCID_SEQ_MAX) 281 ids->seq = 0; 282 } else { 283 new->seq = ipcid_to_seqx(next_id); 284 ids->next_id = -1; 285 } 286 287 new->id = ipc_buildid(id, new->seq); 288 return id; 289 } 290 291 /** 292 * ipcget_new - create a new ipc object 293 * @ns: ipc namespace 294 * @ids: ipc identifier set 295 * @ops: the actual creation routine to call 296 * @params: its parameters 297 * 298 * This routine is called by sys_msgget, sys_semget() and sys_shmget() 299 * when the key is IPC_PRIVATE. 300 */ 301 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, 302 const struct ipc_ops *ops, struct ipc_params *params) 303 { 304 int err; 305 306 down_write(&ids->rwsem); 307 err = ops->getnew(ns, params); 308 up_write(&ids->rwsem); 309 return err; 310 } 311 312 /** 313 * ipc_check_perms - check security and permissions for an ipc object 314 * @ns: ipc namespace 315 * @ipcp: ipc permission set 316 * @ops: the actual security routine to call 317 * @params: its parameters 318 * 319 * This routine is called by sys_msgget(), sys_semget() and sys_shmget() 320 * when the key is not IPC_PRIVATE and that key already exists in the 321 * ds IDR. 322 * 323 * On success, the ipc id is returned. 324 * 325 * It is called with ipc_ids.rwsem and ipcp->lock held. 326 */ 327 static int ipc_check_perms(struct ipc_namespace *ns, 328 struct kern_ipc_perm *ipcp, 329 const struct ipc_ops *ops, 330 struct ipc_params *params) 331 { 332 int err; 333 334 if (ipcperms(ns, ipcp, params->flg)) 335 err = -EACCES; 336 else { 337 err = ops->associate(ipcp, params->flg); 338 if (!err) 339 err = ipcp->id; 340 } 341 342 return err; 343 } 344 345 /** 346 * ipcget_public - get an ipc object or create a new one 347 * @ns: ipc namespace 348 * @ids: ipc identifier set 349 * @ops: the actual creation routine to call 350 * @params: its parameters 351 * 352 * This routine is called by sys_msgget, sys_semget() and sys_shmget() 353 * when the key is not IPC_PRIVATE. 354 * It adds a new entry if the key is not found and does some permission 355 * / security checkings if the key is found. 356 * 357 * On success, the ipc id is returned. 358 */ 359 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, 360 const struct ipc_ops *ops, struct ipc_params *params) 361 { 362 struct kern_ipc_perm *ipcp; 363 int flg = params->flg; 364 int err; 365 366 /* 367 * Take the lock as a writer since we are potentially going to add 368 * a new entry + read locks are not "upgradable" 369 */ 370 down_write(&ids->rwsem); 371 ipcp = ipc_findkey(ids, params->key); 372 if (ipcp == NULL) { 373 /* key not used */ 374 if (!(flg & IPC_CREAT)) 375 err = -ENOENT; 376 else 377 err = ops->getnew(ns, params); 378 } else { 379 /* ipc object has been locked by ipc_findkey() */ 380 381 if (flg & IPC_CREAT && flg & IPC_EXCL) 382 err = -EEXIST; 383 else { 384 err = 0; 385 if (ops->more_checks) 386 err = ops->more_checks(ipcp, params); 387 if (!err) 388 /* 389 * ipc_check_perms returns the IPC id on 390 * success 391 */ 392 err = ipc_check_perms(ns, ipcp, ops, params); 393 } 394 ipc_unlock(ipcp); 395 } 396 up_write(&ids->rwsem); 397 398 return err; 399 } 400 401 /** 402 * ipc_kht_remove - remove an ipc from the key hashtable 403 * @ids: ipc identifier set 404 * @ipcp: ipc perm structure containing the key to remove 405 * 406 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held 407 * before this function is called, and remain locked on the exit. 408 */ 409 static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) 410 { 411 if (ipcp->key != IPC_PRIVATE) 412 rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode, 413 ipc_kht_params); 414 } 415 416 /** 417 * ipc_rmid - remove an ipc identifier 418 * @ids: ipc identifier set 419 * @ipcp: ipc perm structure containing the identifier to remove 420 * 421 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held 422 * before this function is called, and remain locked on the exit. 423 */ 424 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) 425 { 426 int lid = ipcid_to_idx(ipcp->id); 427 428 idr_remove(&ids->ipcs_idr, lid); 429 ipc_kht_remove(ids, ipcp); 430 ids->in_use--; 431 ipcp->deleted = true; 432 } 433 434 /** 435 * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE 436 * @ids: ipc identifier set 437 * @ipcp: ipc perm structure containing the key to modify 438 * 439 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held 440 * before this function is called, and remain locked on the exit. 441 */ 442 void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) 443 { 444 ipc_kht_remove(ids, ipcp); 445 ipcp->key = IPC_PRIVATE; 446 } 447 448 int ipc_rcu_getref(struct kern_ipc_perm *ptr) 449 { 450 return refcount_inc_not_zero(&ptr->refcount); 451 } 452 453 void ipc_rcu_putref(struct kern_ipc_perm *ptr, 454 void (*func)(struct rcu_head *head)) 455 { 456 if (!refcount_dec_and_test(&ptr->refcount)) 457 return; 458 459 call_rcu(&ptr->rcu, func); 460 } 461 462 /** 463 * ipcperms - check ipc permissions 464 * @ns: ipc namespace 465 * @ipcp: ipc permission set 466 * @flag: desired permission set 467 * 468 * Check user, group, other permissions for access 469 * to ipc resources. return 0 if allowed 470 * 471 * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h> 472 */ 473 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) 474 { 475 kuid_t euid = current_euid(); 476 int requested_mode, granted_mode; 477 478 audit_ipc_obj(ipcp); 479 requested_mode = (flag >> 6) | (flag >> 3) | flag; 480 granted_mode = ipcp->mode; 481 if (uid_eq(euid, ipcp->cuid) || 482 uid_eq(euid, ipcp->uid)) 483 granted_mode >>= 6; 484 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid)) 485 granted_mode >>= 3; 486 /* is there some bit set in requested_mode but not in granted_mode? */ 487 if ((requested_mode & ~granted_mode & 0007) && 488 !ns_capable(ns->user_ns, CAP_IPC_OWNER)) 489 return -1; 490 491 return security_ipc_permission(ipcp, flag); 492 } 493 494 /* 495 * Functions to convert between the kern_ipc_perm structure and the 496 * old/new ipc_perm structures 497 */ 498 499 /** 500 * kernel_to_ipc64_perm - convert kernel ipc permissions to user 501 * @in: kernel permissions 502 * @out: new style ipc permissions 503 * 504 * Turn the kernel object @in into a set of permissions descriptions 505 * for returning to userspace (@out). 506 */ 507 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out) 508 { 509 out->key = in->key; 510 out->uid = from_kuid_munged(current_user_ns(), in->uid); 511 out->gid = from_kgid_munged(current_user_ns(), in->gid); 512 out->cuid = from_kuid_munged(current_user_ns(), in->cuid); 513 out->cgid = from_kgid_munged(current_user_ns(), in->cgid); 514 out->mode = in->mode; 515 out->seq = in->seq; 516 } 517 518 /** 519 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old 520 * @in: new style ipc permissions 521 * @out: old style ipc permissions 522 * 523 * Turn the new style permissions object @in into a compatibility 524 * object and store it into the @out pointer. 525 */ 526 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out) 527 { 528 out->key = in->key; 529 SET_UID(out->uid, in->uid); 530 SET_GID(out->gid, in->gid); 531 SET_UID(out->cuid, in->cuid); 532 SET_GID(out->cgid, in->cgid); 533 out->mode = in->mode; 534 out->seq = in->seq; 535 } 536 537 /** 538 * ipc_obtain_object_idr 539 * @ids: ipc identifier set 540 * @id: ipc id to look for 541 * 542 * Look for an id in the ipc ids idr and return associated ipc object. 543 * 544 * Call inside the RCU critical section. 545 * The ipc object is *not* locked on exit. 546 */ 547 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id) 548 { 549 struct kern_ipc_perm *out; 550 int lid = ipcid_to_idx(id); 551 552 if (unlikely(!ids->tables_initialized)) 553 return ERR_PTR(-EINVAL); 554 555 out = idr_find(&ids->ipcs_idr, lid); 556 if (!out) 557 return ERR_PTR(-EINVAL); 558 559 return out; 560 } 561 562 /** 563 * ipc_lock - lock an ipc structure without rwsem held 564 * @ids: ipc identifier set 565 * @id: ipc id to look for 566 * 567 * Look for an id in the ipc ids idr and lock the associated ipc object. 568 * 569 * The ipc object is locked on successful exit. 570 */ 571 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) 572 { 573 struct kern_ipc_perm *out; 574 575 rcu_read_lock(); 576 out = ipc_obtain_object_idr(ids, id); 577 if (IS_ERR(out)) 578 goto err; 579 580 spin_lock(&out->lock); 581 582 /* 583 * ipc_rmid() may have already freed the ID while ipc_lock() 584 * was spinning: here verify that the structure is still valid. 585 * Upon races with RMID, return -EIDRM, thus indicating that 586 * the ID points to a removed identifier. 587 */ 588 if (ipc_valid_object(out)) 589 return out; 590 591 spin_unlock(&out->lock); 592 out = ERR_PTR(-EIDRM); 593 err: 594 rcu_read_unlock(); 595 return out; 596 } 597 598 /** 599 * ipc_obtain_object_check 600 * @ids: ipc identifier set 601 * @id: ipc id to look for 602 * 603 * Similar to ipc_obtain_object_idr() but also checks 604 * the ipc object reference counter. 605 * 606 * Call inside the RCU critical section. 607 * The ipc object is *not* locked on exit. 608 */ 609 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id) 610 { 611 struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id); 612 613 if (IS_ERR(out)) 614 goto out; 615 616 if (ipc_checkid(out, id)) 617 return ERR_PTR(-EINVAL); 618 out: 619 return out; 620 } 621 622 /** 623 * ipcget - Common sys_*get() code 624 * @ns: namespace 625 * @ids: ipc identifier set 626 * @ops: operations to be called on ipc object creation, permission checks 627 * and further checks 628 * @params: the parameters needed by the previous operations. 629 * 630 * Common routine called by sys_msgget(), sys_semget() and sys_shmget(). 631 */ 632 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, 633 const struct ipc_ops *ops, struct ipc_params *params) 634 { 635 if (params->key == IPC_PRIVATE) 636 return ipcget_new(ns, ids, ops, params); 637 else 638 return ipcget_public(ns, ids, ops, params); 639 } 640 641 /** 642 * ipc_update_perm - update the permissions of an ipc object 643 * @in: the permission given as input. 644 * @out: the permission of the ipc to set. 645 */ 646 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) 647 { 648 kuid_t uid = make_kuid(current_user_ns(), in->uid); 649 kgid_t gid = make_kgid(current_user_ns(), in->gid); 650 if (!uid_valid(uid) || !gid_valid(gid)) 651 return -EINVAL; 652 653 out->uid = uid; 654 out->gid = gid; 655 out->mode = (out->mode & ~S_IRWXUGO) 656 | (in->mode & S_IRWXUGO); 657 658 return 0; 659 } 660 661 /** 662 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd 663 * @ns: ipc namespace 664 * @ids: the table of ids where to look for the ipc 665 * @id: the id of the ipc to retrieve 666 * @cmd: the cmd to check 667 * @perm: the permission to set 668 * @extra_perm: one extra permission parameter used by msq 669 * 670 * This function does some common audit and permissions check for some IPC_XXX 671 * cmd and is called from semctl_down, shmctl_down and msgctl_down. 672 * It must be called without any lock held and: 673 * 674 * - retrieves the ipc with the given id in the given table. 675 * - performs some audit and permission check, depending on the given cmd 676 * - returns a pointer to the ipc object or otherwise, the corresponding 677 * error. 678 * 679 * Call holding the both the rwsem and the rcu read lock. 680 */ 681 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, 682 struct ipc_ids *ids, int id, int cmd, 683 struct ipc64_perm *perm, int extra_perm) 684 { 685 kuid_t euid; 686 int err = -EPERM; 687 struct kern_ipc_perm *ipcp; 688 689 ipcp = ipc_obtain_object_check(ids, id); 690 if (IS_ERR(ipcp)) { 691 err = PTR_ERR(ipcp); 692 goto err; 693 } 694 695 audit_ipc_obj(ipcp); 696 if (cmd == IPC_SET) 697 audit_ipc_set_perm(extra_perm, perm->uid, 698 perm->gid, perm->mode); 699 700 euid = current_euid(); 701 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) || 702 ns_capable(ns->user_ns, CAP_SYS_ADMIN)) 703 return ipcp; /* successful lookup */ 704 err: 705 return ERR_PTR(err); 706 } 707 708 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION 709 710 711 /** 712 * ipc_parse_version - ipc call version 713 * @cmd: pointer to command 714 * 715 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC. 716 * The @cmd value is turned from an encoding command and version into 717 * just the command code. 718 */ 719 int ipc_parse_version(int *cmd) 720 { 721 if (*cmd & IPC_64) { 722 *cmd ^= IPC_64; 723 return IPC_64; 724 } else { 725 return IPC_OLD; 726 } 727 } 728 729 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */ 730 731 #ifdef CONFIG_PROC_FS 732 struct ipc_proc_iter { 733 struct ipc_namespace *ns; 734 struct ipc_proc_iface *iface; 735 }; 736 737 /* 738 * This routine locks the ipc structure found at least at position pos. 739 */ 740 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, 741 loff_t *new_pos) 742 { 743 struct kern_ipc_perm *ipc; 744 int total, id; 745 746 total = 0; 747 for (id = 0; id < pos && total < ids->in_use; id++) { 748 ipc = idr_find(&ids->ipcs_idr, id); 749 if (ipc != NULL) 750 total++; 751 } 752 753 if (total >= ids->in_use) 754 return NULL; 755 756 for (; pos < IPCMNI; pos++) { 757 ipc = idr_find(&ids->ipcs_idr, pos); 758 if (ipc != NULL) { 759 *new_pos = pos + 1; 760 rcu_read_lock(); 761 ipc_lock_object(ipc); 762 return ipc; 763 } 764 } 765 766 /* Out of range - return NULL to terminate iteration */ 767 return NULL; 768 } 769 770 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) 771 { 772 struct ipc_proc_iter *iter = s->private; 773 struct ipc_proc_iface *iface = iter->iface; 774 struct kern_ipc_perm *ipc = it; 775 776 /* If we had an ipc id locked before, unlock it */ 777 if (ipc && ipc != SEQ_START_TOKEN) 778 ipc_unlock(ipc); 779 780 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); 781 } 782 783 /* 784 * File positions: pos 0 -> header, pos n -> ipc id = n - 1. 785 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. 786 */ 787 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) 788 { 789 struct ipc_proc_iter *iter = s->private; 790 struct ipc_proc_iface *iface = iter->iface; 791 struct ipc_ids *ids; 792 793 ids = &iter->ns->ids[iface->ids]; 794 795 /* 796 * Take the lock - this will be released by the corresponding 797 * call to stop(). 798 */ 799 down_read(&ids->rwsem); 800 801 /* pos < 0 is invalid */ 802 if (*pos < 0) 803 return NULL; 804 805 /* pos == 0 means header */ 806 if (*pos == 0) 807 return SEQ_START_TOKEN; 808 809 /* Find the (pos-1)th ipc */ 810 return sysvipc_find_ipc(ids, *pos - 1, pos); 811 } 812 813 static void sysvipc_proc_stop(struct seq_file *s, void *it) 814 { 815 struct kern_ipc_perm *ipc = it; 816 struct ipc_proc_iter *iter = s->private; 817 struct ipc_proc_iface *iface = iter->iface; 818 struct ipc_ids *ids; 819 820 /* If we had a locked structure, release it */ 821 if (ipc && ipc != SEQ_START_TOKEN) 822 ipc_unlock(ipc); 823 824 ids = &iter->ns->ids[iface->ids]; 825 /* Release the lock we took in start() */ 826 up_read(&ids->rwsem); 827 } 828 829 static int sysvipc_proc_show(struct seq_file *s, void *it) 830 { 831 struct ipc_proc_iter *iter = s->private; 832 struct ipc_proc_iface *iface = iter->iface; 833 834 if (it == SEQ_START_TOKEN) { 835 seq_puts(s, iface->header); 836 return 0; 837 } 838 839 return iface->show(s, it); 840 } 841 842 static const struct seq_operations sysvipc_proc_seqops = { 843 .start = sysvipc_proc_start, 844 .stop = sysvipc_proc_stop, 845 .next = sysvipc_proc_next, 846 .show = sysvipc_proc_show, 847 }; 848 849 static int sysvipc_proc_open(struct inode *inode, struct file *file) 850 { 851 struct ipc_proc_iter *iter; 852 853 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter)); 854 if (!iter) 855 return -ENOMEM; 856 857 iter->iface = PDE_DATA(inode); 858 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); 859 860 return 0; 861 } 862 863 static int sysvipc_proc_release(struct inode *inode, struct file *file) 864 { 865 struct seq_file *seq = file->private_data; 866 struct ipc_proc_iter *iter = seq->private; 867 put_ipc_ns(iter->ns); 868 return seq_release_private(inode, file); 869 } 870 871 static const struct file_operations sysvipc_proc_fops = { 872 .open = sysvipc_proc_open, 873 .read = seq_read, 874 .llseek = seq_lseek, 875 .release = sysvipc_proc_release, 876 }; 877 #endif /* CONFIG_PROC_FS */ 878