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