| 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 | |
| 67 | #include <asm/unistd.h> |
| 68 | |
| 69 | #include "util.h" |
| 70 | |
| 71 | struct ipc_proc_iface { |
| 72 | const char *path; |
| 73 | const char *header; |
| 74 | int ids; |
| 75 | int (*show)(struct seq_file *, void *); |
| 76 | }; |
| 77 | |
| 78 | /** |
| 79 | * ipc_init - initialise ipc subsystem |
| 80 | * |
| 81 | * The various sysv ipc resources (semaphores, messages and shared |
| 82 | * memory) are initialised. |
| 83 | * |
| 84 | * A callback routine is registered into the memory hotplug notifier |
| 85 | * chain: since msgmni scales to lowmem this callback routine will be |
| 86 | * called upon successful memory add / remove to recompute msmgni. |
| 87 | */ |
| 88 | static int __init ipc_init(void) |
| 89 | { |
| 90 | int err_sem, err_msg; |
| 91 | |
| 92 | proc_mkdir("sysvipc", NULL); |
| 93 | err_sem = sem_init(); |
| 94 | WARN(err_sem, "ipc: sysv sem_init failed: %d\n", err_sem); |
| 95 | err_msg = msg_init(); |
| 96 | WARN(err_msg, "ipc: sysv msg_init failed: %d\n", err_msg); |
| 97 | shm_init(); |
| 98 | |
| 99 | return err_msg ? err_msg : err_sem; |
| 100 | } |
| 101 | device_initcall(ipc_init); |
| 102 | |
| 103 | static const struct rhashtable_params ipc_kht_params = { |
| 104 | .head_offset = offsetof(struct kern_ipc_perm, khtnode), |
| 105 | .key_offset = offsetof(struct kern_ipc_perm, key), |
| 106 | .key_len = FIELD_SIZEOF(struct kern_ipc_perm, key), |
| 107 | .locks_mul = 1, |
| 108 | .automatic_shrinking = true, |
| 109 | }; |
| 110 | |
| 111 | /** |
| 112 | * ipc_init_ids - initialise ipc identifiers |
| 113 | * @ids: ipc identifier set |
| 114 | * |
| 115 | * Set up the sequence range to use for the ipc identifier range (limited |
| 116 | * below IPCMNI) then initialise the keys hashtable and ids idr. |
| 117 | */ |
| 118 | int ipc_init_ids(struct ipc_ids *ids) |
| 119 | { |
| 120 | int err; |
| 121 | ids->in_use = 0; |
| 122 | ids->seq = 0; |
| 123 | init_rwsem(&ids->rwsem); |
| 124 | err = rhashtable_init(&ids->key_ht, &ipc_kht_params); |
| 125 | if (err) |
| 126 | return err; |
| 127 | idr_init(&ids->ipcs_idr); |
| 128 | ids->tables_initialized = true; |
| 129 | ids->max_id = -1; |
| 130 | #ifdef CONFIG_CHECKPOINT_RESTORE |
| 131 | ids->next_id = -1; |
| 132 | #endif |
| 133 | return 0; |
| 134 | } |
| 135 | |
| 136 | #ifdef CONFIG_PROC_FS |
| 137 | static const struct file_operations sysvipc_proc_fops; |
| 138 | /** |
| 139 | * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface. |
| 140 | * @path: Path in procfs |
| 141 | * @header: Banner to be printed at the beginning of the file. |
| 142 | * @ids: ipc id table to iterate. |
| 143 | * @show: show routine. |
| 144 | */ |
| 145 | void __init ipc_init_proc_interface(const char *path, const char *header, |
| 146 | int ids, int (*show)(struct seq_file *, void *)) |
| 147 | { |
| 148 | struct proc_dir_entry *pde; |
| 149 | struct ipc_proc_iface *iface; |
| 150 | |
| 151 | iface = kmalloc(sizeof(*iface), GFP_KERNEL); |
| 152 | if (!iface) |
| 153 | return; |
| 154 | iface->path = path; |
| 155 | iface->header = header; |
| 156 | iface->ids = ids; |
| 157 | iface->show = show; |
| 158 | |
| 159 | pde = proc_create_data(path, |
| 160 | S_IRUGO, /* world readable */ |
| 161 | NULL, /* parent dir */ |
| 162 | &sysvipc_proc_fops, |
| 163 | iface); |
| 164 | if (!pde) |
| 165 | kfree(iface); |
| 166 | } |
| 167 | #endif |
| 168 | |
| 169 | /** |
| 170 | * ipc_findkey - find a key in an ipc identifier set |
| 171 | * @ids: ipc identifier set |
| 172 | * @key: key to find |
| 173 | * |
| 174 | * Returns the locked pointer to the ipc structure if found or NULL |
| 175 | * otherwise. If key is found ipc points to the owning ipc structure |
| 176 | * |
| 177 | * Called with writer ipc_ids.rwsem held. |
| 178 | */ |
| 179 | static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) |
| 180 | { |
| 181 | struct kern_ipc_perm *ipcp = NULL; |
| 182 | |
| 183 | if (likely(ids->tables_initialized)) |
| 184 | ipcp = rhashtable_lookup_fast(&ids->key_ht, &key, |
| 185 | ipc_kht_params); |
| 186 | |
| 187 | if (ipcp) { |
| 188 | rcu_read_lock(); |
| 189 | ipc_lock_object(ipcp); |
| 190 | return ipcp; |
| 191 | } |
| 192 | |
| 193 | return NULL; |
| 194 | } |
| 195 | |
| 196 | #ifdef CONFIG_CHECKPOINT_RESTORE |
| 197 | /* |
| 198 | * Specify desired id for next allocated IPC object. |
| 199 | */ |
| 200 | #define ipc_idr_alloc(ids, new) \ |
| 201 | idr_alloc(&(ids)->ipcs_idr, (new), \ |
| 202 | (ids)->next_id < 0 ? 0 : ipcid_to_idx((ids)->next_id),\ |
| 203 | 0, GFP_NOWAIT) |
| 204 | |
| 205 | static inline int ipc_buildid(int id, struct ipc_ids *ids, |
| 206 | struct kern_ipc_perm *new) |
| 207 | { |
| 208 | if (ids->next_id < 0) { /* default, behave as !CHECKPOINT_RESTORE */ |
| 209 | new->seq = ids->seq++; |
| 210 | if (ids->seq > IPCID_SEQ_MAX) |
| 211 | ids->seq = 0; |
| 212 | } else { |
| 213 | new->seq = ipcid_to_seqx(ids->next_id); |
| 214 | ids->next_id = -1; |
| 215 | } |
| 216 | |
| 217 | return SEQ_MULTIPLIER * new->seq + id; |
| 218 | } |
| 219 | |
| 220 | #else |
| 221 | #define ipc_idr_alloc(ids, new) \ |
| 222 | idr_alloc(&(ids)->ipcs_idr, (new), 0, 0, GFP_NOWAIT) |
| 223 | |
| 224 | static inline int ipc_buildid(int id, struct ipc_ids *ids, |
| 225 | struct kern_ipc_perm *new) |
| 226 | { |
| 227 | new->seq = ids->seq++; |
| 228 | if (ids->seq > IPCID_SEQ_MAX) |
| 229 | ids->seq = 0; |
| 230 | |
| 231 | return SEQ_MULTIPLIER * new->seq + id; |
| 232 | } |
| 233 | |
| 234 | #endif /* CONFIG_CHECKPOINT_RESTORE */ |
| 235 | |
| 236 | /** |
| 237 | * ipc_addid - add an ipc identifier |
| 238 | * @ids: ipc identifier set |
| 239 | * @new: new ipc permission set |
| 240 | * @limit: limit for the number of used ids |
| 241 | * |
| 242 | * Add an entry 'new' to the ipc ids idr. The permissions object is |
| 243 | * initialised and the first free entry is set up and the id assigned |
| 244 | * is returned. The 'new' entry is returned in a locked state on success. |
| 245 | * On failure the entry is not locked and a negative err-code is returned. |
| 246 | * |
| 247 | * Called with writer ipc_ids.rwsem held. |
| 248 | */ |
| 249 | int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit) |
| 250 | { |
| 251 | kuid_t euid; |
| 252 | kgid_t egid; |
| 253 | int id, err; |
| 254 | |
| 255 | if (limit > IPCMNI) |
| 256 | limit = IPCMNI; |
| 257 | |
| 258 | if (!ids->tables_initialized || ids->in_use >= limit) |
| 259 | return -ENOSPC; |
| 260 | |
| 261 | idr_preload(GFP_KERNEL); |
| 262 | |
| 263 | refcount_set(&new->refcount, 1); |
| 264 | spin_lock_init(&new->lock); |
| 265 | new->deleted = false; |
| 266 | rcu_read_lock(); |
| 267 | spin_lock(&new->lock); |
| 268 | |
| 269 | current_euid_egid(&euid, &egid); |
| 270 | new->cuid = new->uid = euid; |
| 271 | new->gid = new->cgid = egid; |
| 272 | |
| 273 | id = ipc_idr_alloc(ids, new); |
| 274 | idr_preload_end(); |
| 275 | |
| 276 | if (id >= 0 && new->key != IPC_PRIVATE) { |
| 277 | err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode, |
| 278 | ipc_kht_params); |
| 279 | if (err < 0) { |
| 280 | idr_remove(&ids->ipcs_idr, id); |
| 281 | id = err; |
| 282 | } |
| 283 | } |
| 284 | if (id < 0) { |
| 285 | spin_unlock(&new->lock); |
| 286 | rcu_read_unlock(); |
| 287 | return id; |
| 288 | } |
| 289 | |
| 290 | ids->in_use++; |
| 291 | if (id > ids->max_id) |
| 292 | ids->max_id = id; |
| 293 | |
| 294 | new->id = ipc_buildid(id, ids, new); |
| 295 | |
| 296 | return id; |
| 297 | } |
| 298 | |
| 299 | /** |
| 300 | * ipcget_new - create a new ipc object |
| 301 | * @ns: ipc namespace |
| 302 | * @ids: ipc identifier set |
| 303 | * @ops: the actual creation routine to call |
| 304 | * @params: its parameters |
| 305 | * |
| 306 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() |
| 307 | * when the key is IPC_PRIVATE. |
| 308 | */ |
| 309 | static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, |
| 310 | const struct ipc_ops *ops, struct ipc_params *params) |
| 311 | { |
| 312 | int err; |
| 313 | |
| 314 | down_write(&ids->rwsem); |
| 315 | err = ops->getnew(ns, params); |
| 316 | up_write(&ids->rwsem); |
| 317 | return err; |
| 318 | } |
| 319 | |
| 320 | /** |
| 321 | * ipc_check_perms - check security and permissions for an ipc object |
| 322 | * @ns: ipc namespace |
| 323 | * @ipcp: ipc permission set |
| 324 | * @ops: the actual security routine to call |
| 325 | * @params: its parameters |
| 326 | * |
| 327 | * This routine is called by sys_msgget(), sys_semget() and sys_shmget() |
| 328 | * when the key is not IPC_PRIVATE and that key already exists in the |
| 329 | * ds IDR. |
| 330 | * |
| 331 | * On success, the ipc id is returned. |
| 332 | * |
| 333 | * It is called with ipc_ids.rwsem and ipcp->lock held. |
| 334 | */ |
| 335 | static int ipc_check_perms(struct ipc_namespace *ns, |
| 336 | struct kern_ipc_perm *ipcp, |
| 337 | const struct ipc_ops *ops, |
| 338 | struct ipc_params *params) |
| 339 | { |
| 340 | int err; |
| 341 | |
| 342 | if (ipcperms(ns, ipcp, params->flg)) |
| 343 | err = -EACCES; |
| 344 | else { |
| 345 | err = ops->associate(ipcp, params->flg); |
| 346 | if (!err) |
| 347 | err = ipcp->id; |
| 348 | } |
| 349 | |
| 350 | return err; |
| 351 | } |
| 352 | |
| 353 | /** |
| 354 | * ipcget_public - get an ipc object or create a new one |
| 355 | * @ns: ipc namespace |
| 356 | * @ids: ipc identifier set |
| 357 | * @ops: the actual creation routine to call |
| 358 | * @params: its parameters |
| 359 | * |
| 360 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() |
| 361 | * when the key is not IPC_PRIVATE. |
| 362 | * It adds a new entry if the key is not found and does some permission |
| 363 | * / security checkings if the key is found. |
| 364 | * |
| 365 | * On success, the ipc id is returned. |
| 366 | */ |
| 367 | static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, |
| 368 | const struct ipc_ops *ops, struct ipc_params *params) |
| 369 | { |
| 370 | struct kern_ipc_perm *ipcp; |
| 371 | int flg = params->flg; |
| 372 | int err; |
| 373 | |
| 374 | /* |
| 375 | * Take the lock as a writer since we are potentially going to add |
| 376 | * a new entry + read locks are not "upgradable" |
| 377 | */ |
| 378 | down_write(&ids->rwsem); |
| 379 | ipcp = ipc_findkey(ids, params->key); |
| 380 | if (ipcp == NULL) { |
| 381 | /* key not used */ |
| 382 | if (!(flg & IPC_CREAT)) |
| 383 | err = -ENOENT; |
| 384 | else |
| 385 | err = ops->getnew(ns, params); |
| 386 | } else { |
| 387 | /* ipc object has been locked by ipc_findkey() */ |
| 388 | |
| 389 | if (flg & IPC_CREAT && flg & IPC_EXCL) |
| 390 | err = -EEXIST; |
| 391 | else { |
| 392 | err = 0; |
| 393 | if (ops->more_checks) |
| 394 | err = ops->more_checks(ipcp, params); |
| 395 | if (!err) |
| 396 | /* |
| 397 | * ipc_check_perms returns the IPC id on |
| 398 | * success |
| 399 | */ |
| 400 | err = ipc_check_perms(ns, ipcp, ops, params); |
| 401 | } |
| 402 | ipc_unlock(ipcp); |
| 403 | } |
| 404 | up_write(&ids->rwsem); |
| 405 | |
| 406 | return err; |
| 407 | } |
| 408 | |
| 409 | /** |
| 410 | * ipc_kht_remove - remove an ipc from the key hashtable |
| 411 | * @ids: ipc identifier set |
| 412 | * @ipcp: ipc perm structure containing the key to remove |
| 413 | * |
| 414 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held |
| 415 | * before this function is called, and remain locked on the exit. |
| 416 | */ |
| 417 | static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) |
| 418 | { |
| 419 | if (ipcp->key != IPC_PRIVATE) |
| 420 | rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode, |
| 421 | ipc_kht_params); |
| 422 | } |
| 423 | |
| 424 | /** |
| 425 | * ipc_rmid - remove an ipc identifier |
| 426 | * @ids: ipc identifier set |
| 427 | * @ipcp: ipc perm structure containing the identifier to remove |
| 428 | * |
| 429 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held |
| 430 | * before this function is called, and remain locked on the exit. |
| 431 | */ |
| 432 | void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) |
| 433 | { |
| 434 | int lid = ipcid_to_idx(ipcp->id); |
| 435 | |
| 436 | idr_remove(&ids->ipcs_idr, lid); |
| 437 | ipc_kht_remove(ids, ipcp); |
| 438 | ids->in_use--; |
| 439 | ipcp->deleted = true; |
| 440 | |
| 441 | if (unlikely(lid == ids->max_id)) { |
| 442 | do { |
| 443 | lid--; |
| 444 | if (lid == -1) |
| 445 | break; |
| 446 | } while (!idr_find(&ids->ipcs_idr, lid)); |
| 447 | ids->max_id = lid; |
| 448 | } |
| 449 | } |
| 450 | |
| 451 | /** |
| 452 | * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE |
| 453 | * @ids: ipc identifier set |
| 454 | * @ipcp: ipc perm structure containing the key to modify |
| 455 | * |
| 456 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held |
| 457 | * before this function is called, and remain locked on the exit. |
| 458 | */ |
| 459 | void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) |
| 460 | { |
| 461 | ipc_kht_remove(ids, ipcp); |
| 462 | ipcp->key = IPC_PRIVATE; |
| 463 | } |
| 464 | |
| 465 | int ipc_rcu_getref(struct kern_ipc_perm *ptr) |
| 466 | { |
| 467 | return refcount_inc_not_zero(&ptr->refcount); |
| 468 | } |
| 469 | |
| 470 | void ipc_rcu_putref(struct kern_ipc_perm *ptr, |
| 471 | void (*func)(struct rcu_head *head)) |
| 472 | { |
| 473 | if (!refcount_dec_and_test(&ptr->refcount)) |
| 474 | return; |
| 475 | |
| 476 | call_rcu(&ptr->rcu, func); |
| 477 | } |
| 478 | |
| 479 | /** |
| 480 | * ipcperms - check ipc permissions |
| 481 | * @ns: ipc namespace |
| 482 | * @ipcp: ipc permission set |
| 483 | * @flag: desired permission set |
| 484 | * |
| 485 | * Check user, group, other permissions for access |
| 486 | * to ipc resources. return 0 if allowed |
| 487 | * |
| 488 | * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h> |
| 489 | */ |
| 490 | int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) |
| 491 | { |
| 492 | kuid_t euid = current_euid(); |
| 493 | int requested_mode, granted_mode; |
| 494 | |
| 495 | audit_ipc_obj(ipcp); |
| 496 | requested_mode = (flag >> 6) | (flag >> 3) | flag; |
| 497 | granted_mode = ipcp->mode; |
| 498 | if (uid_eq(euid, ipcp->cuid) || |
| 499 | uid_eq(euid, ipcp->uid)) |
| 500 | granted_mode >>= 6; |
| 501 | else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid)) |
| 502 | granted_mode >>= 3; |
| 503 | /* is there some bit set in requested_mode but not in granted_mode? */ |
| 504 | if ((requested_mode & ~granted_mode & 0007) && |
| 505 | !ns_capable(ns->user_ns, CAP_IPC_OWNER)) |
| 506 | return -1; |
| 507 | |
| 508 | return security_ipc_permission(ipcp, flag); |
| 509 | } |
| 510 | |
| 511 | /* |
| 512 | * Functions to convert between the kern_ipc_perm structure and the |
| 513 | * old/new ipc_perm structures |
| 514 | */ |
| 515 | |
| 516 | /** |
| 517 | * kernel_to_ipc64_perm - convert kernel ipc permissions to user |
| 518 | * @in: kernel permissions |
| 519 | * @out: new style ipc permissions |
| 520 | * |
| 521 | * Turn the kernel object @in into a set of permissions descriptions |
| 522 | * for returning to userspace (@out). |
| 523 | */ |
| 524 | void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out) |
| 525 | { |
| 526 | out->key = in->key; |
| 527 | out->uid = from_kuid_munged(current_user_ns(), in->uid); |
| 528 | out->gid = from_kgid_munged(current_user_ns(), in->gid); |
| 529 | out->cuid = from_kuid_munged(current_user_ns(), in->cuid); |
| 530 | out->cgid = from_kgid_munged(current_user_ns(), in->cgid); |
| 531 | out->mode = in->mode; |
| 532 | out->seq = in->seq; |
| 533 | } |
| 534 | |
| 535 | /** |
| 536 | * ipc64_perm_to_ipc_perm - convert new ipc permissions to old |
| 537 | * @in: new style ipc permissions |
| 538 | * @out: old style ipc permissions |
| 539 | * |
| 540 | * Turn the new style permissions object @in into a compatibility |
| 541 | * object and store it into the @out pointer. |
| 542 | */ |
| 543 | void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out) |
| 544 | { |
| 545 | out->key = in->key; |
| 546 | SET_UID(out->uid, in->uid); |
| 547 | SET_GID(out->gid, in->gid); |
| 548 | SET_UID(out->cuid, in->cuid); |
| 549 | SET_GID(out->cgid, in->cgid); |
| 550 | out->mode = in->mode; |
| 551 | out->seq = in->seq; |
| 552 | } |
| 553 | |
| 554 | /** |
| 555 | * ipc_obtain_object_idr |
| 556 | * @ids: ipc identifier set |
| 557 | * @id: ipc id to look for |
| 558 | * |
| 559 | * Look for an id in the ipc ids idr and return associated ipc object. |
| 560 | * |
| 561 | * Call inside the RCU critical section. |
| 562 | * The ipc object is *not* locked on exit. |
| 563 | */ |
| 564 | struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id) |
| 565 | { |
| 566 | struct kern_ipc_perm *out; |
| 567 | int lid = ipcid_to_idx(id); |
| 568 | |
| 569 | if (unlikely(!ids->tables_initialized)) |
| 570 | return ERR_PTR(-EINVAL); |
| 571 | |
| 572 | out = idr_find(&ids->ipcs_idr, lid); |
| 573 | if (!out) |
| 574 | return ERR_PTR(-EINVAL); |
| 575 | |
| 576 | return out; |
| 577 | } |
| 578 | |
| 579 | /** |
| 580 | * ipc_lock - lock an ipc structure without rwsem held |
| 581 | * @ids: ipc identifier set |
| 582 | * @id: ipc id to look for |
| 583 | * |
| 584 | * Look for an id in the ipc ids idr and lock the associated ipc object. |
| 585 | * |
| 586 | * The ipc object is locked on successful exit. |
| 587 | */ |
| 588 | struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) |
| 589 | { |
| 590 | struct kern_ipc_perm *out; |
| 591 | |
| 592 | rcu_read_lock(); |
| 593 | out = ipc_obtain_object_idr(ids, id); |
| 594 | if (IS_ERR(out)) |
| 595 | goto err; |
| 596 | |
| 597 | spin_lock(&out->lock); |
| 598 | |
| 599 | /* |
| 600 | * ipc_rmid() may have already freed the ID while ipc_lock() |
| 601 | * was spinning: here verify that the structure is still valid. |
| 602 | * Upon races with RMID, return -EIDRM, thus indicating that |
| 603 | * the ID points to a removed identifier. |
| 604 | */ |
| 605 | if (ipc_valid_object(out)) |
| 606 | return out; |
| 607 | |
| 608 | spin_unlock(&out->lock); |
| 609 | out = ERR_PTR(-EIDRM); |
| 610 | err: |
| 611 | rcu_read_unlock(); |
| 612 | return out; |
| 613 | } |
| 614 | |
| 615 | /** |
| 616 | * ipc_obtain_object_check |
| 617 | * @ids: ipc identifier set |
| 618 | * @id: ipc id to look for |
| 619 | * |
| 620 | * Similar to ipc_obtain_object_idr() but also checks |
| 621 | * the ipc object reference counter. |
| 622 | * |
| 623 | * Call inside the RCU critical section. |
| 624 | * The ipc object is *not* locked on exit. |
| 625 | */ |
| 626 | struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id) |
| 627 | { |
| 628 | struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id); |
| 629 | |
| 630 | if (IS_ERR(out)) |
| 631 | goto out; |
| 632 | |
| 633 | if (ipc_checkid(out, id)) |
| 634 | return ERR_PTR(-EINVAL); |
| 635 | out: |
| 636 | return out; |
| 637 | } |
| 638 | |
| 639 | /** |
| 640 | * ipcget - Common sys_*get() code |
| 641 | * @ns: namespace |
| 642 | * @ids: ipc identifier set |
| 643 | * @ops: operations to be called on ipc object creation, permission checks |
| 644 | * and further checks |
| 645 | * @params: the parameters needed by the previous operations. |
| 646 | * |
| 647 | * Common routine called by sys_msgget(), sys_semget() and sys_shmget(). |
| 648 | */ |
| 649 | int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, |
| 650 | const struct ipc_ops *ops, struct ipc_params *params) |
| 651 | { |
| 652 | if (params->key == IPC_PRIVATE) |
| 653 | return ipcget_new(ns, ids, ops, params); |
| 654 | else |
| 655 | return ipcget_public(ns, ids, ops, params); |
| 656 | } |
| 657 | |
| 658 | /** |
| 659 | * ipc_update_perm - update the permissions of an ipc object |
| 660 | * @in: the permission given as input. |
| 661 | * @out: the permission of the ipc to set. |
| 662 | */ |
| 663 | int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) |
| 664 | { |
| 665 | kuid_t uid = make_kuid(current_user_ns(), in->uid); |
| 666 | kgid_t gid = make_kgid(current_user_ns(), in->gid); |
| 667 | if (!uid_valid(uid) || !gid_valid(gid)) |
| 668 | return -EINVAL; |
| 669 | |
| 670 | out->uid = uid; |
| 671 | out->gid = gid; |
| 672 | out->mode = (out->mode & ~S_IRWXUGO) |
| 673 | | (in->mode & S_IRWXUGO); |
| 674 | |
| 675 | return 0; |
| 676 | } |
| 677 | |
| 678 | /** |
| 679 | * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd |
| 680 | * @ns: ipc namespace |
| 681 | * @ids: the table of ids where to look for the ipc |
| 682 | * @id: the id of the ipc to retrieve |
| 683 | * @cmd: the cmd to check |
| 684 | * @perm: the permission to set |
| 685 | * @extra_perm: one extra permission parameter used by msq |
| 686 | * |
| 687 | * This function does some common audit and permissions check for some IPC_XXX |
| 688 | * cmd and is called from semctl_down, shmctl_down and msgctl_down. |
| 689 | * It must be called without any lock held and: |
| 690 | * |
| 691 | * - retrieves the ipc with the given id in the given table. |
| 692 | * - performs some audit and permission check, depending on the given cmd |
| 693 | * - returns a pointer to the ipc object or otherwise, the corresponding |
| 694 | * error. |
| 695 | * |
| 696 | * Call holding the both the rwsem and the rcu read lock. |
| 697 | */ |
| 698 | struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, |
| 699 | struct ipc_ids *ids, int id, int cmd, |
| 700 | struct ipc64_perm *perm, int extra_perm) |
| 701 | { |
| 702 | kuid_t euid; |
| 703 | int err = -EPERM; |
| 704 | struct kern_ipc_perm *ipcp; |
| 705 | |
| 706 | ipcp = ipc_obtain_object_check(ids, id); |
| 707 | if (IS_ERR(ipcp)) { |
| 708 | err = PTR_ERR(ipcp); |
| 709 | goto err; |
| 710 | } |
| 711 | |
| 712 | audit_ipc_obj(ipcp); |
| 713 | if (cmd == IPC_SET) |
| 714 | audit_ipc_set_perm(extra_perm, perm->uid, |
| 715 | perm->gid, perm->mode); |
| 716 | |
| 717 | euid = current_euid(); |
| 718 | if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) || |
| 719 | ns_capable(ns->user_ns, CAP_SYS_ADMIN)) |
| 720 | return ipcp; /* successful lookup */ |
| 721 | err: |
| 722 | return ERR_PTR(err); |
| 723 | } |
| 724 | |
| 725 | #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION |
| 726 | |
| 727 | |
| 728 | /** |
| 729 | * ipc_parse_version - ipc call version |
| 730 | * @cmd: pointer to command |
| 731 | * |
| 732 | * Return IPC_64 for new style IPC and IPC_OLD for old style IPC. |
| 733 | * The @cmd value is turned from an encoding command and version into |
| 734 | * just the command code. |
| 735 | */ |
| 736 | int ipc_parse_version(int *cmd) |
| 737 | { |
| 738 | if (*cmd & IPC_64) { |
| 739 | *cmd ^= IPC_64; |
| 740 | return IPC_64; |
| 741 | } else { |
| 742 | return IPC_OLD; |
| 743 | } |
| 744 | } |
| 745 | |
| 746 | #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */ |
| 747 | |
| 748 | #ifdef CONFIG_PROC_FS |
| 749 | struct ipc_proc_iter { |
| 750 | struct ipc_namespace *ns; |
| 751 | struct pid_namespace *pid_ns; |
| 752 | struct ipc_proc_iface *iface; |
| 753 | }; |
| 754 | |
| 755 | struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s) |
| 756 | { |
| 757 | struct ipc_proc_iter *iter = s->private; |
| 758 | return iter->pid_ns; |
| 759 | } |
| 760 | |
| 761 | /* |
| 762 | * This routine locks the ipc structure found at least at position pos. |
| 763 | */ |
| 764 | static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, |
| 765 | loff_t *new_pos) |
| 766 | { |
| 767 | struct kern_ipc_perm *ipc; |
| 768 | int total, id; |
| 769 | |
| 770 | total = 0; |
| 771 | for (id = 0; id < pos && total < ids->in_use; id++) { |
| 772 | ipc = idr_find(&ids->ipcs_idr, id); |
| 773 | if (ipc != NULL) |
| 774 | total++; |
| 775 | } |
| 776 | |
| 777 | if (total >= ids->in_use) |
| 778 | return NULL; |
| 779 | |
| 780 | for (; pos < IPCMNI; pos++) { |
| 781 | ipc = idr_find(&ids->ipcs_idr, pos); |
| 782 | if (ipc != NULL) { |
| 783 | *new_pos = pos + 1; |
| 784 | rcu_read_lock(); |
| 785 | ipc_lock_object(ipc); |
| 786 | return ipc; |
| 787 | } |
| 788 | } |
| 789 | |
| 790 | /* Out of range - return NULL to terminate iteration */ |
| 791 | return NULL; |
| 792 | } |
| 793 | |
| 794 | static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) |
| 795 | { |
| 796 | struct ipc_proc_iter *iter = s->private; |
| 797 | struct ipc_proc_iface *iface = iter->iface; |
| 798 | struct kern_ipc_perm *ipc = it; |
| 799 | |
| 800 | /* If we had an ipc id locked before, unlock it */ |
| 801 | if (ipc && ipc != SEQ_START_TOKEN) |
| 802 | ipc_unlock(ipc); |
| 803 | |
| 804 | return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); |
| 805 | } |
| 806 | |
| 807 | /* |
| 808 | * File positions: pos 0 -> header, pos n -> ipc id = n - 1. |
| 809 | * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. |
| 810 | */ |
| 811 | static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) |
| 812 | { |
| 813 | struct ipc_proc_iter *iter = s->private; |
| 814 | struct ipc_proc_iface *iface = iter->iface; |
| 815 | struct ipc_ids *ids; |
| 816 | |
| 817 | ids = &iter->ns->ids[iface->ids]; |
| 818 | |
| 819 | /* |
| 820 | * Take the lock - this will be released by the corresponding |
| 821 | * call to stop(). |
| 822 | */ |
| 823 | down_read(&ids->rwsem); |
| 824 | |
| 825 | /* pos < 0 is invalid */ |
| 826 | if (*pos < 0) |
| 827 | return NULL; |
| 828 | |
| 829 | /* pos == 0 means header */ |
| 830 | if (*pos == 0) |
| 831 | return SEQ_START_TOKEN; |
| 832 | |
| 833 | /* Find the (pos-1)th ipc */ |
| 834 | return sysvipc_find_ipc(ids, *pos - 1, pos); |
| 835 | } |
| 836 | |
| 837 | static void sysvipc_proc_stop(struct seq_file *s, void *it) |
| 838 | { |
| 839 | struct kern_ipc_perm *ipc = it; |
| 840 | struct ipc_proc_iter *iter = s->private; |
| 841 | struct ipc_proc_iface *iface = iter->iface; |
| 842 | struct ipc_ids *ids; |
| 843 | |
| 844 | /* If we had a locked structure, release it */ |
| 845 | if (ipc && ipc != SEQ_START_TOKEN) |
| 846 | ipc_unlock(ipc); |
| 847 | |
| 848 | ids = &iter->ns->ids[iface->ids]; |
| 849 | /* Release the lock we took in start() */ |
| 850 | up_read(&ids->rwsem); |
| 851 | } |
| 852 | |
| 853 | static int sysvipc_proc_show(struct seq_file *s, void *it) |
| 854 | { |
| 855 | struct ipc_proc_iter *iter = s->private; |
| 856 | struct ipc_proc_iface *iface = iter->iface; |
| 857 | |
| 858 | if (it == SEQ_START_TOKEN) { |
| 859 | seq_puts(s, iface->header); |
| 860 | return 0; |
| 861 | } |
| 862 | |
| 863 | return iface->show(s, it); |
| 864 | } |
| 865 | |
| 866 | static const struct seq_operations sysvipc_proc_seqops = { |
| 867 | .start = sysvipc_proc_start, |
| 868 | .stop = sysvipc_proc_stop, |
| 869 | .next = sysvipc_proc_next, |
| 870 | .show = sysvipc_proc_show, |
| 871 | }; |
| 872 | |
| 873 | static int sysvipc_proc_open(struct inode *inode, struct file *file) |
| 874 | { |
| 875 | struct ipc_proc_iter *iter; |
| 876 | |
| 877 | iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter)); |
| 878 | if (!iter) |
| 879 | return -ENOMEM; |
| 880 | |
| 881 | iter->iface = PDE_DATA(inode); |
| 882 | iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); |
| 883 | iter->pid_ns = get_pid_ns(task_active_pid_ns(current)); |
| 884 | |
| 885 | return 0; |
| 886 | } |
| 887 | |
| 888 | static int sysvipc_proc_release(struct inode *inode, struct file *file) |
| 889 | { |
| 890 | struct seq_file *seq = file->private_data; |
| 891 | struct ipc_proc_iter *iter = seq->private; |
| 892 | put_ipc_ns(iter->ns); |
| 893 | put_pid_ns(iter->pid_ns); |
| 894 | return seq_release_private(inode, file); |
| 895 | } |
| 896 | |
| 897 | static const struct file_operations sysvipc_proc_fops = { |
| 898 | .open = sysvipc_proc_open, |
| 899 | .read = seq_read, |
| 900 | .llseek = seq_lseek, |
| 901 | .release = sysvipc_proc_release, |
| 902 | }; |
| 903 | #endif /* CONFIG_PROC_FS */ |