1 /* 2 * linux/ipc/util.c 3 * Copyright (C) 1992 Krishna Balasubramanian 4 * 5 * Sep 1997 - Call suser() last after "normal" permission checks so we 6 * get BSD style process accounting right. 7 * Occurs in several places in the IPC code. 8 * Chris Evans, <chris@ferret.lmh.ox.ac.uk> 9 * Nov 1999 - ipc helper functions, unified SMP locking 10 * Manfred Spraul <manfred@colorfullife.com> 11 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary(). 12 * Mingming Cao <cmm@us.ibm.com> 13 * Mar 2006 - support for audit of ipc object properties 14 * Dustin Kirkland <dustin.kirkland@us.ibm.com> 15 * Jun 2006 - namespaces ssupport 16 * OpenVZ, SWsoft Inc. 17 * Pavel Emelianov <xemul@openvz.org> 18 */ 19 20 #include <linux/mm.h> 21 #include <linux/shm.h> 22 #include <linux/init.h> 23 #include <linux/msg.h> 24 #include <linux/vmalloc.h> 25 #include <linux/slab.h> 26 #include <linux/notifier.h> 27 #include <linux/capability.h> 28 #include <linux/highuid.h> 29 #include <linux/security.h> 30 #include <linux/rcupdate.h> 31 #include <linux/workqueue.h> 32 #include <linux/seq_file.h> 33 #include <linux/proc_fs.h> 34 #include <linux/audit.h> 35 #include <linux/nsproxy.h> 36 #include <linux/rwsem.h> 37 #include <linux/memory.h> 38 #include <linux/ipc_namespace.h> 39 40 #include <asm/unistd.h> 41 42 #include "util.h" 43 44 struct ipc_proc_iface { 45 const char *path; 46 const char *header; 47 int ids; 48 int (*show)(struct seq_file *, void *); 49 }; 50 51 static void ipc_memory_notifier(struct work_struct *work) 52 { 53 ipcns_notify(IPCNS_MEMCHANGED); 54 } 55 56 static int ipc_memory_callback(struct notifier_block *self, 57 unsigned long action, void *arg) 58 { 59 static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier); 60 61 switch (action) { 62 case MEM_ONLINE: /* memory successfully brought online */ 63 case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */ 64 /* 65 * This is done by invoking the ipcns notifier chain with the 66 * IPC_MEMCHANGED event. 67 * In order not to keep the lock on the hotplug memory chain 68 * for too long, queue a work item that will, when waken up, 69 * activate the ipcns notification chain. 70 * No need to keep several ipc work items on the queue. 71 */ 72 if (!work_pending(&ipc_memory_wq)) 73 schedule_work(&ipc_memory_wq); 74 break; 75 case MEM_GOING_ONLINE: 76 case MEM_GOING_OFFLINE: 77 case MEM_CANCEL_ONLINE: 78 case MEM_CANCEL_OFFLINE: 79 default: 80 break; 81 } 82 83 return NOTIFY_OK; 84 } 85 86 static struct notifier_block ipc_memory_nb = { 87 .notifier_call = ipc_memory_callback, 88 .priority = IPC_CALLBACK_PRI, 89 }; 90 91 /** 92 * ipc_init - initialise IPC subsystem 93 * 94 * The various system5 IPC resources (semaphores, messages and shared 95 * memory) are initialised 96 * A callback routine is registered into the memory hotplug notifier 97 * chain: since msgmni scales to lowmem this callback routine will be 98 * called upon successful memory add / remove to recompute msmgni. 99 */ 100 101 static int __init ipc_init(void) 102 { 103 sem_init(); 104 msg_init(); 105 shm_init(); 106 register_hotmemory_notifier(&ipc_memory_nb); 107 register_ipcns_notifier(&init_ipc_ns); 108 return 0; 109 } 110 __initcall(ipc_init); 111 112 /** 113 * ipc_init_ids - initialise IPC identifiers 114 * @ids: Identifier set 115 * 116 * Set up the sequence range to use for the ipc identifier range (limited 117 * below IPCMNI) then initialise the ids idr. 118 */ 119 120 void ipc_init_ids(struct ipc_ids *ids) 121 { 122 init_rwsem(&ids->rw_mutex); 123 124 ids->in_use = 0; 125 ids->seq = 0; 126 ids->next_id = -1; 127 { 128 int seq_limit = INT_MAX/SEQ_MULTIPLIER; 129 if (seq_limit > USHRT_MAX) 130 ids->seq_max = USHRT_MAX; 131 else 132 ids->seq_max = seq_limit; 133 } 134 135 idr_init(&ids->ipcs_idr); 136 } 137 138 #ifdef CONFIG_PROC_FS 139 static const struct file_operations sysvipc_proc_fops; 140 /** 141 * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface. 142 * @path: Path in procfs 143 * @header: Banner to be printed at the beginning of the file. 144 * @ids: ipc id table to iterate. 145 * @show: show routine. 146 */ 147 void __init ipc_init_proc_interface(const char *path, const char *header, 148 int ids, int (*show)(struct seq_file *, void *)) 149 { 150 struct proc_dir_entry *pde; 151 struct ipc_proc_iface *iface; 152 153 iface = kmalloc(sizeof(*iface), GFP_KERNEL); 154 if (!iface) 155 return; 156 iface->path = path; 157 iface->header = header; 158 iface->ids = ids; 159 iface->show = show; 160 161 pde = proc_create_data(path, 162 S_IRUGO, /* world readable */ 163 NULL, /* parent dir */ 164 &sysvipc_proc_fops, 165 iface); 166 if (!pde) { 167 kfree(iface); 168 } 169 } 170 #endif 171 172 /** 173 * ipc_findkey - find a key in an ipc identifier set 174 * @ids: Identifier set 175 * @key: The key to find 176 * 177 * Requires ipc_ids.rw_mutex locked. 178 * Returns the LOCKED pointer to the ipc structure if found or NULL 179 * if not. 180 * If key is found ipc points to the owning ipc structure 181 */ 182 183 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) 184 { 185 struct kern_ipc_perm *ipc; 186 int next_id; 187 int total; 188 189 for (total = 0, next_id = 0; total < ids->in_use; next_id++) { 190 ipc = idr_find(&ids->ipcs_idr, next_id); 191 192 if (ipc == NULL) 193 continue; 194 195 if (ipc->key != key) { 196 total++; 197 continue; 198 } 199 200 ipc_lock_by_ptr(ipc); 201 return ipc; 202 } 203 204 return NULL; 205 } 206 207 /** 208 * ipc_get_maxid - get the last assigned id 209 * @ids: IPC identifier set 210 * 211 * Called with ipc_ids.rw_mutex held. 212 */ 213 214 int ipc_get_maxid(struct ipc_ids *ids) 215 { 216 struct kern_ipc_perm *ipc; 217 int max_id = -1; 218 int total, id; 219 220 if (ids->in_use == 0) 221 return -1; 222 223 if (ids->in_use == IPCMNI) 224 return IPCMNI - 1; 225 226 /* Look for the last assigned id */ 227 total = 0; 228 for (id = 0; id < IPCMNI && total < ids->in_use; id++) { 229 ipc = idr_find(&ids->ipcs_idr, id); 230 if (ipc != NULL) { 231 max_id = id; 232 total++; 233 } 234 } 235 return max_id; 236 } 237 238 /** 239 * ipc_addid - add an IPC identifier 240 * @ids: IPC identifier set 241 * @new: new IPC permission set 242 * @size: limit for the number of used ids 243 * 244 * Add an entry 'new' to the IPC ids idr. The permissions object is 245 * initialised and the first free entry is set up and the id assigned 246 * is returned. The 'new' entry is returned in a locked state on success. 247 * On failure the entry is not locked and a negative err-code is returned. 248 * 249 * Called with ipc_ids.rw_mutex held as a writer. 250 */ 251 252 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) 253 { 254 kuid_t euid; 255 kgid_t egid; 256 int id; 257 int next_id = ids->next_id; 258 259 if (size > IPCMNI) 260 size = IPCMNI; 261 262 if (ids->in_use >= size) 263 return -ENOSPC; 264 265 idr_preload(GFP_KERNEL); 266 267 spin_lock_init(&new->lock); 268 new->deleted = 0; 269 rcu_read_lock(); 270 spin_lock(&new->lock); 271 272 id = idr_alloc(&ids->ipcs_idr, new, 273 (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0, 274 GFP_NOWAIT); 275 idr_preload_end(); 276 if (id < 0) { 277 spin_unlock(&new->lock); 278 rcu_read_unlock(); 279 return id; 280 } 281 282 ids->in_use++; 283 284 current_euid_egid(&euid, &egid); 285 new->cuid = new->uid = euid; 286 new->gid = new->cgid = egid; 287 288 if (next_id < 0) { 289 new->seq = ids->seq++; 290 if (ids->seq > ids->seq_max) 291 ids->seq = 0; 292 } else { 293 new->seq = ipcid_to_seqx(next_id); 294 ids->next_id = -1; 295 } 296 297 new->id = ipc_buildid(id, new->seq); 298 return id; 299 } 300 301 /** 302 * ipcget_new - create a new ipc object 303 * @ns: namespace 304 * @ids: IPC identifer set 305 * @ops: the actual creation routine to call 306 * @params: its parameters 307 * 308 * This routine is called by sys_msgget, sys_semget() and sys_shmget() 309 * when the key is IPC_PRIVATE. 310 */ 311 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, 312 struct ipc_ops *ops, struct ipc_params *params) 313 { 314 int err; 315 316 down_write(&ids->rw_mutex); 317 err = ops->getnew(ns, params); 318 up_write(&ids->rw_mutex); 319 return err; 320 } 321 322 /** 323 * ipc_check_perms - check security and permissions for an IPC 324 * @ns: IPC namespace 325 * @ipcp: ipc permission set 326 * @ops: the actual security routine to call 327 * @params: its parameters 328 * 329 * This routine is called by sys_msgget(), sys_semget() and sys_shmget() 330 * when the key is not IPC_PRIVATE and that key already exists in the 331 * ids IDR. 332 * 333 * On success, the IPC id is returned. 334 * 335 * It is called with ipc_ids.rw_mutex and ipcp->lock held. 336 */ 337 static int ipc_check_perms(struct ipc_namespace *ns, 338 struct kern_ipc_perm *ipcp, 339 struct ipc_ops *ops, 340 struct ipc_params *params) 341 { 342 int err; 343 344 if (ipcperms(ns, ipcp, params->flg)) 345 err = -EACCES; 346 else { 347 err = ops->associate(ipcp, params->flg); 348 if (!err) 349 err = ipcp->id; 350 } 351 352 return err; 353 } 354 355 /** 356 * ipcget_public - get an ipc object or create a new one 357 * @ns: namespace 358 * @ids: IPC identifer set 359 * @ops: the actual creation routine to call 360 * @params: its parameters 361 * 362 * This routine is called by sys_msgget, sys_semget() and sys_shmget() 363 * when the key is not IPC_PRIVATE. 364 * It adds a new entry if the key is not found and does some permission 365 * / security checkings if the key is found. 366 * 367 * On success, the ipc id is returned. 368 */ 369 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, 370 struct ipc_ops *ops, struct ipc_params *params) 371 { 372 struct kern_ipc_perm *ipcp; 373 int flg = params->flg; 374 int err; 375 376 /* 377 * Take the lock as a writer since we are potentially going to add 378 * a new entry + read locks are not "upgradable" 379 */ 380 down_write(&ids->rw_mutex); 381 ipcp = ipc_findkey(ids, params->key); 382 if (ipcp == NULL) { 383 /* key not used */ 384 if (!(flg & IPC_CREAT)) 385 err = -ENOENT; 386 else 387 err = ops->getnew(ns, params); 388 } else { 389 /* ipc object has been locked by ipc_findkey() */ 390 391 if (flg & IPC_CREAT && flg & IPC_EXCL) 392 err = -EEXIST; 393 else { 394 err = 0; 395 if (ops->more_checks) 396 err = ops->more_checks(ipcp, params); 397 if (!err) 398 /* 399 * ipc_check_perms returns the IPC id on 400 * success 401 */ 402 err = ipc_check_perms(ns, ipcp, ops, params); 403 } 404 ipc_unlock(ipcp); 405 } 406 up_write(&ids->rw_mutex); 407 408 return err; 409 } 410 411 412 /** 413 * ipc_rmid - remove an IPC identifier 414 * @ids: IPC identifier set 415 * @ipcp: ipc perm structure containing the identifier to remove 416 * 417 * ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held 418 * before this function is called, and remain locked on the exit. 419 */ 420 421 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) 422 { 423 int lid = ipcid_to_idx(ipcp->id); 424 425 idr_remove(&ids->ipcs_idr, lid); 426 427 ids->in_use--; 428 429 ipcp->deleted = 1; 430 431 return; 432 } 433 434 /** 435 * ipc_alloc - allocate ipc space 436 * @size: size desired 437 * 438 * Allocate memory from the appropriate pools and return a pointer to it. 439 * NULL is returned if the allocation fails 440 */ 441 442 void *ipc_alloc(int size) 443 { 444 void *out; 445 if(size > PAGE_SIZE) 446 out = vmalloc(size); 447 else 448 out = kmalloc(size, GFP_KERNEL); 449 return out; 450 } 451 452 /** 453 * ipc_free - free ipc space 454 * @ptr: pointer returned by ipc_alloc 455 * @size: size of block 456 * 457 * Free a block created with ipc_alloc(). The caller must know the size 458 * used in the allocation call. 459 */ 460 461 void ipc_free(void* ptr, int size) 462 { 463 if(size > PAGE_SIZE) 464 vfree(ptr); 465 else 466 kfree(ptr); 467 } 468 469 struct ipc_rcu { 470 struct rcu_head rcu; 471 atomic_t refcount; 472 /* "void *" makes sure alignment of following data is sane. */ 473 void *data[0]; 474 }; 475 476 /** 477 * ipc_rcu_alloc - allocate ipc and rcu space 478 * @size: size desired 479 * 480 * Allocate memory for the rcu header structure + the object. 481 * Returns the pointer to the object or NULL upon failure. 482 */ 483 void *ipc_rcu_alloc(int size) 484 { 485 /* 486 * We prepend the allocation with the rcu struct 487 */ 488 struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size); 489 if (unlikely(!out)) 490 return NULL; 491 atomic_set(&out->refcount, 1); 492 return out->data; 493 } 494 495 int ipc_rcu_getref(void *ptr) 496 { 497 return atomic_inc_not_zero(&container_of(ptr, struct ipc_rcu, data)->refcount); 498 } 499 500 /** 501 * ipc_schedule_free - free ipc + rcu space 502 * @head: RCU callback structure for queued work 503 */ 504 static void ipc_schedule_free(struct rcu_head *head) 505 { 506 vfree(container_of(head, struct ipc_rcu, rcu)); 507 } 508 509 void ipc_rcu_putref(void *ptr) 510 { 511 struct ipc_rcu *p = container_of(ptr, struct ipc_rcu, data); 512 513 if (!atomic_dec_and_test(&p->refcount)) 514 return; 515 516 if (is_vmalloc_addr(ptr)) { 517 call_rcu(&p->rcu, ipc_schedule_free); 518 } else { 519 kfree_rcu(p, rcu); 520 } 521 } 522 523 /** 524 * ipcperms - check IPC permissions 525 * @ns: IPC namespace 526 * @ipcp: IPC permission set 527 * @flag: desired permission set. 528 * 529 * Check user, group, other permissions for access 530 * to ipc resources. return 0 if allowed 531 * 532 * @flag will most probably be 0 or S_...UGO from <linux/stat.h> 533 */ 534 535 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) 536 { 537 kuid_t euid = current_euid(); 538 int requested_mode, granted_mode; 539 540 audit_ipc_obj(ipcp); 541 requested_mode = (flag >> 6) | (flag >> 3) | flag; 542 granted_mode = ipcp->mode; 543 if (uid_eq(euid, ipcp->cuid) || 544 uid_eq(euid, ipcp->uid)) 545 granted_mode >>= 6; 546 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid)) 547 granted_mode >>= 3; 548 /* is there some bit set in requested_mode but not in granted_mode? */ 549 if ((requested_mode & ~granted_mode & 0007) && 550 !ns_capable(ns->user_ns, CAP_IPC_OWNER)) 551 return -1; 552 553 return security_ipc_permission(ipcp, flag); 554 } 555 556 /* 557 * Functions to convert between the kern_ipc_perm structure and the 558 * old/new ipc_perm structures 559 */ 560 561 /** 562 * kernel_to_ipc64_perm - convert kernel ipc permissions to user 563 * @in: kernel permissions 564 * @out: new style IPC permissions 565 * 566 * Turn the kernel object @in into a set of permissions descriptions 567 * for returning to userspace (@out). 568 */ 569 570 571 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out) 572 { 573 out->key = in->key; 574 out->uid = from_kuid_munged(current_user_ns(), in->uid); 575 out->gid = from_kgid_munged(current_user_ns(), in->gid); 576 out->cuid = from_kuid_munged(current_user_ns(), in->cuid); 577 out->cgid = from_kgid_munged(current_user_ns(), in->cgid); 578 out->mode = in->mode; 579 out->seq = in->seq; 580 } 581 582 /** 583 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old 584 * @in: new style IPC permissions 585 * @out: old style IPC permissions 586 * 587 * Turn the new style permissions object @in into a compatibility 588 * object and store it into the @out pointer. 589 */ 590 591 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out) 592 { 593 out->key = in->key; 594 SET_UID(out->uid, in->uid); 595 SET_GID(out->gid, in->gid); 596 SET_UID(out->cuid, in->cuid); 597 SET_GID(out->cgid, in->cgid); 598 out->mode = in->mode; 599 out->seq = in->seq; 600 } 601 602 /** 603 * ipc_obtain_object 604 * @ids: ipc identifier set 605 * @id: ipc id to look for 606 * 607 * Look for an id in the ipc ids idr and return associated ipc object. 608 * 609 * Call inside the RCU critical section. 610 * The ipc object is *not* locked on exit. 611 */ 612 struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id) 613 { 614 struct kern_ipc_perm *out; 615 int lid = ipcid_to_idx(id); 616 617 out = idr_find(&ids->ipcs_idr, lid); 618 if (!out) 619 return ERR_PTR(-EINVAL); 620 621 return out; 622 } 623 624 /** 625 * ipc_lock - Lock an ipc structure without rw_mutex held 626 * @ids: IPC identifier set 627 * @id: ipc id to look for 628 * 629 * Look for an id in the ipc ids idr and lock the associated ipc object. 630 * 631 * The ipc object is locked on successful exit. 632 */ 633 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) 634 { 635 struct kern_ipc_perm *out; 636 637 rcu_read_lock(); 638 out = ipc_obtain_object(ids, id); 639 if (IS_ERR(out)) 640 goto err1; 641 642 spin_lock(&out->lock); 643 644 /* ipc_rmid() may have already freed the ID while ipc_lock 645 * was spinning: here verify that the structure is still valid 646 */ 647 if (!out->deleted) 648 return out; 649 650 spin_unlock(&out->lock); 651 out = ERR_PTR(-EINVAL); 652 err1: 653 rcu_read_unlock(); 654 return out; 655 } 656 657 /** 658 * ipc_obtain_object_check 659 * @ids: ipc identifier set 660 * @id: ipc id to look for 661 * 662 * Similar to ipc_obtain_object() but also checks 663 * the ipc object reference counter. 664 * 665 * Call inside the RCU critical section. 666 * The ipc object is *not* locked on exit. 667 */ 668 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id) 669 { 670 struct kern_ipc_perm *out = ipc_obtain_object(ids, id); 671 672 if (IS_ERR(out)) 673 goto out; 674 675 if (ipc_checkid(out, id)) 676 return ERR_PTR(-EIDRM); 677 out: 678 return out; 679 } 680 681 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id) 682 { 683 struct kern_ipc_perm *out; 684 685 out = ipc_lock(ids, id); 686 if (IS_ERR(out)) 687 return out; 688 689 if (ipc_checkid(out, id)) { 690 ipc_unlock(out); 691 return ERR_PTR(-EIDRM); 692 } 693 694 return out; 695 } 696 697 /** 698 * ipcget - Common sys_*get() code 699 * @ns : namsepace 700 * @ids : IPC identifier set 701 * @ops : operations to be called on ipc object creation, permission checks 702 * and further checks 703 * @params : the parameters needed by the previous operations. 704 * 705 * Common routine called by sys_msgget(), sys_semget() and sys_shmget(). 706 */ 707 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, 708 struct ipc_ops *ops, struct ipc_params *params) 709 { 710 if (params->key == IPC_PRIVATE) 711 return ipcget_new(ns, ids, ops, params); 712 else 713 return ipcget_public(ns, ids, ops, params); 714 } 715 716 /** 717 * ipc_update_perm - update the permissions of an IPC. 718 * @in: the permission given as input. 719 * @out: the permission of the ipc to set. 720 */ 721 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) 722 { 723 kuid_t uid = make_kuid(current_user_ns(), in->uid); 724 kgid_t gid = make_kgid(current_user_ns(), in->gid); 725 if (!uid_valid(uid) || !gid_valid(gid)) 726 return -EINVAL; 727 728 out->uid = uid; 729 out->gid = gid; 730 out->mode = (out->mode & ~S_IRWXUGO) 731 | (in->mode & S_IRWXUGO); 732 733 return 0; 734 } 735 736 /** 737 * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd 738 * @ns: the ipc namespace 739 * @ids: the table of ids where to look for the ipc 740 * @id: the id of the ipc to retrieve 741 * @cmd: the cmd to check 742 * @perm: the permission to set 743 * @extra_perm: one extra permission parameter used by msq 744 * 745 * This function does some common audit and permissions check for some IPC_XXX 746 * cmd and is called from semctl_down, shmctl_down and msgctl_down. 747 * It must be called without any lock held and 748 * - retrieves the ipc with the given id in the given table. 749 * - performs some audit and permission check, depending on the given cmd 750 * - returns the ipc with both ipc and rw_mutex locks held in case of success 751 * or an err-code without any lock held otherwise. 752 */ 753 struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns, 754 struct ipc_ids *ids, int id, int cmd, 755 struct ipc64_perm *perm, int extra_perm) 756 { 757 struct kern_ipc_perm *ipcp; 758 759 ipcp = ipcctl_pre_down_nolock(ns, ids, id, cmd, perm, extra_perm); 760 if (IS_ERR(ipcp)) 761 goto out; 762 763 spin_lock(&ipcp->lock); 764 out: 765 return ipcp; 766 } 767 768 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, 769 struct ipc_ids *ids, int id, int cmd, 770 struct ipc64_perm *perm, int extra_perm) 771 { 772 kuid_t euid; 773 int err = -EPERM; 774 struct kern_ipc_perm *ipcp; 775 776 down_write(&ids->rw_mutex); 777 rcu_read_lock(); 778 779 ipcp = ipc_obtain_object_check(ids, id); 780 if (IS_ERR(ipcp)) { 781 err = PTR_ERR(ipcp); 782 goto out_up; 783 } 784 785 audit_ipc_obj(ipcp); 786 if (cmd == IPC_SET) 787 audit_ipc_set_perm(extra_perm, perm->uid, 788 perm->gid, perm->mode); 789 790 euid = current_euid(); 791 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) || 792 ns_capable(ns->user_ns, CAP_SYS_ADMIN)) 793 return ipcp; 794 795 out_up: 796 /* 797 * Unsuccessful lookup, unlock and return 798 * the corresponding error. 799 */ 800 rcu_read_unlock(); 801 up_write(&ids->rw_mutex); 802 803 return ERR_PTR(err); 804 } 805 806 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION 807 808 809 /** 810 * ipc_parse_version - IPC call version 811 * @cmd: pointer to command 812 * 813 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC. 814 * The @cmd value is turned from an encoding command and version into 815 * just the command code. 816 */ 817 818 int ipc_parse_version (int *cmd) 819 { 820 if (*cmd & IPC_64) { 821 *cmd ^= IPC_64; 822 return IPC_64; 823 } else { 824 return IPC_OLD; 825 } 826 } 827 828 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */ 829 830 #ifdef CONFIG_PROC_FS 831 struct ipc_proc_iter { 832 struct ipc_namespace *ns; 833 struct ipc_proc_iface *iface; 834 }; 835 836 /* 837 * This routine locks the ipc structure found at least at position pos. 838 */ 839 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, 840 loff_t *new_pos) 841 { 842 struct kern_ipc_perm *ipc; 843 int total, id; 844 845 total = 0; 846 for (id = 0; id < pos && total < ids->in_use; id++) { 847 ipc = idr_find(&ids->ipcs_idr, id); 848 if (ipc != NULL) 849 total++; 850 } 851 852 if (total >= ids->in_use) 853 return NULL; 854 855 for ( ; pos < IPCMNI; pos++) { 856 ipc = idr_find(&ids->ipcs_idr, pos); 857 if (ipc != NULL) { 858 *new_pos = pos + 1; 859 ipc_lock_by_ptr(ipc); 860 return ipc; 861 } 862 } 863 864 /* Out of range - return NULL to terminate iteration */ 865 return NULL; 866 } 867 868 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) 869 { 870 struct ipc_proc_iter *iter = s->private; 871 struct ipc_proc_iface *iface = iter->iface; 872 struct kern_ipc_perm *ipc = it; 873 874 /* If we had an ipc id locked before, unlock it */ 875 if (ipc && ipc != SEQ_START_TOKEN) 876 ipc_unlock(ipc); 877 878 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); 879 } 880 881 /* 882 * File positions: pos 0 -> header, pos n -> ipc id = n - 1. 883 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. 884 */ 885 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) 886 { 887 struct ipc_proc_iter *iter = s->private; 888 struct ipc_proc_iface *iface = iter->iface; 889 struct ipc_ids *ids; 890 891 ids = &iter->ns->ids[iface->ids]; 892 893 /* 894 * Take the lock - this will be released by the corresponding 895 * call to stop(). 896 */ 897 down_read(&ids->rw_mutex); 898 899 /* pos < 0 is invalid */ 900 if (*pos < 0) 901 return NULL; 902 903 /* pos == 0 means header */ 904 if (*pos == 0) 905 return SEQ_START_TOKEN; 906 907 /* Find the (pos-1)th ipc */ 908 return sysvipc_find_ipc(ids, *pos - 1, pos); 909 } 910 911 static void sysvipc_proc_stop(struct seq_file *s, void *it) 912 { 913 struct kern_ipc_perm *ipc = it; 914 struct ipc_proc_iter *iter = s->private; 915 struct ipc_proc_iface *iface = iter->iface; 916 struct ipc_ids *ids; 917 918 /* If we had a locked structure, release it */ 919 if (ipc && ipc != SEQ_START_TOKEN) 920 ipc_unlock(ipc); 921 922 ids = &iter->ns->ids[iface->ids]; 923 /* Release the lock we took in start() */ 924 up_read(&ids->rw_mutex); 925 } 926 927 static int sysvipc_proc_show(struct seq_file *s, void *it) 928 { 929 struct ipc_proc_iter *iter = s->private; 930 struct ipc_proc_iface *iface = iter->iface; 931 932 if (it == SEQ_START_TOKEN) 933 return seq_puts(s, iface->header); 934 935 return iface->show(s, it); 936 } 937 938 static const struct seq_operations sysvipc_proc_seqops = { 939 .start = sysvipc_proc_start, 940 .stop = sysvipc_proc_stop, 941 .next = sysvipc_proc_next, 942 .show = sysvipc_proc_show, 943 }; 944 945 static int sysvipc_proc_open(struct inode *inode, struct file *file) 946 { 947 int ret; 948 struct seq_file *seq; 949 struct ipc_proc_iter *iter; 950 951 ret = -ENOMEM; 952 iter = kmalloc(sizeof(*iter), GFP_KERNEL); 953 if (!iter) 954 goto out; 955 956 ret = seq_open(file, &sysvipc_proc_seqops); 957 if (ret) 958 goto out_kfree; 959 960 seq = file->private_data; 961 seq->private = iter; 962 963 iter->iface = PDE_DATA(inode); 964 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); 965 out: 966 return ret; 967 out_kfree: 968 kfree(iter); 969 goto out; 970 } 971 972 static int sysvipc_proc_release(struct inode *inode, struct file *file) 973 { 974 struct seq_file *seq = file->private_data; 975 struct ipc_proc_iter *iter = seq->private; 976 put_ipc_ns(iter->ns); 977 return seq_release_private(inode, file); 978 } 979 980 static const struct file_operations sysvipc_proc_fops = { 981 .open = sysvipc_proc_open, 982 .read = seq_read, 983 .llseek = seq_lseek, 984 .release = sysvipc_proc_release, 985 }; 986 #endif /* CONFIG_PROC_FS */ 987