| 1 | /* |
| 2 | * linux/ipc/msg.c |
| 3 | * Copyright (C) 1992 Krishna Balasubramanian |
| 4 | * |
| 5 | * Removed all the remaining kerneld mess |
| 6 | * Catch the -EFAULT stuff properly |
| 7 | * Use GFP_KERNEL for messages as in 1.2 |
| 8 | * Fixed up the unchecked user space derefs |
| 9 | * Copyright (C) 1998 Alan Cox & Andi Kleen |
| 10 | * |
| 11 | * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com> |
| 12 | * |
| 13 | * mostly rewritten, threaded and wake-one semantics added |
| 14 | * MSGMAX limit removed, sysctl's added |
| 15 | * (c) 1999 Manfred Spraul <manfred@colorfullife.com> |
| 16 | * |
| 17 | * support for audit of ipc object properties and permission changes |
| 18 | * Dustin Kirkland <dustin.kirkland@us.ibm.com> |
| 19 | * |
| 20 | * namespaces support |
| 21 | * OpenVZ, SWsoft Inc. |
| 22 | * Pavel Emelianov <xemul@openvz.org> |
| 23 | */ |
| 24 | |
| 25 | #include <linux/capability.h> |
| 26 | #include <linux/msg.h> |
| 27 | #include <linux/spinlock.h> |
| 28 | #include <linux/init.h> |
| 29 | #include <linux/mm.h> |
| 30 | #include <linux/proc_fs.h> |
| 31 | #include <linux/list.h> |
| 32 | #include <linux/security.h> |
| 33 | #include <linux/sched.h> |
| 34 | #include <linux/syscalls.h> |
| 35 | #include <linux/audit.h> |
| 36 | #include <linux/seq_file.h> |
| 37 | #include <linux/rwsem.h> |
| 38 | #include <linux/nsproxy.h> |
| 39 | #include <linux/ipc_namespace.h> |
| 40 | |
| 41 | #include <asm/current.h> |
| 42 | #include <linux/uaccess.h> |
| 43 | #include "util.h" |
| 44 | |
| 45 | /* one msg_receiver structure for each sleeping receiver */ |
| 46 | struct msg_receiver { |
| 47 | struct list_head r_list; |
| 48 | struct task_struct *r_tsk; |
| 49 | |
| 50 | int r_mode; |
| 51 | long r_msgtype; |
| 52 | long r_maxsize; |
| 53 | |
| 54 | struct msg_msg *r_msg; |
| 55 | }; |
| 56 | |
| 57 | /* one msg_sender for each sleeping sender */ |
| 58 | struct msg_sender { |
| 59 | struct list_head list; |
| 60 | struct task_struct *tsk; |
| 61 | size_t msgsz; |
| 62 | }; |
| 63 | |
| 64 | #define SEARCH_ANY 1 |
| 65 | #define SEARCH_EQUAL 2 |
| 66 | #define SEARCH_NOTEQUAL 3 |
| 67 | #define SEARCH_LESSEQUAL 4 |
| 68 | #define SEARCH_NUMBER 5 |
| 69 | |
| 70 | #define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS]) |
| 71 | |
| 72 | static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id) |
| 73 | { |
| 74 | struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id); |
| 75 | |
| 76 | if (IS_ERR(ipcp)) |
| 77 | return ERR_CAST(ipcp); |
| 78 | |
| 79 | return container_of(ipcp, struct msg_queue, q_perm); |
| 80 | } |
| 81 | |
| 82 | static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns, |
| 83 | int id) |
| 84 | { |
| 85 | struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id); |
| 86 | |
| 87 | if (IS_ERR(ipcp)) |
| 88 | return ERR_CAST(ipcp); |
| 89 | |
| 90 | return container_of(ipcp, struct msg_queue, q_perm); |
| 91 | } |
| 92 | |
| 93 | static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s) |
| 94 | { |
| 95 | ipc_rmid(&msg_ids(ns), &s->q_perm); |
| 96 | } |
| 97 | |
| 98 | static void msg_rcu_free(struct rcu_head *head) |
| 99 | { |
| 100 | struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); |
| 101 | struct msg_queue *msq = ipc_rcu_to_struct(p); |
| 102 | |
| 103 | security_msg_queue_free(msq); |
| 104 | ipc_rcu_free(head); |
| 105 | } |
| 106 | |
| 107 | /** |
| 108 | * newque - Create a new msg queue |
| 109 | * @ns: namespace |
| 110 | * @params: ptr to the structure that contains the key and msgflg |
| 111 | * |
| 112 | * Called with msg_ids.rwsem held (writer) |
| 113 | */ |
| 114 | static int newque(struct ipc_namespace *ns, struct ipc_params *params) |
| 115 | { |
| 116 | struct msg_queue *msq; |
| 117 | int id, retval; |
| 118 | key_t key = params->key; |
| 119 | int msgflg = params->flg; |
| 120 | |
| 121 | msq = ipc_rcu_alloc(sizeof(*msq)); |
| 122 | if (!msq) |
| 123 | return -ENOMEM; |
| 124 | |
| 125 | msq->q_perm.mode = msgflg & S_IRWXUGO; |
| 126 | msq->q_perm.key = key; |
| 127 | |
| 128 | msq->q_perm.security = NULL; |
| 129 | retval = security_msg_queue_alloc(msq); |
| 130 | if (retval) { |
| 131 | ipc_rcu_putref(msq, ipc_rcu_free); |
| 132 | return retval; |
| 133 | } |
| 134 | |
| 135 | msq->q_stime = msq->q_rtime = 0; |
| 136 | msq->q_ctime = get_seconds(); |
| 137 | msq->q_cbytes = msq->q_qnum = 0; |
| 138 | msq->q_qbytes = ns->msg_ctlmnb; |
| 139 | msq->q_lspid = msq->q_lrpid = 0; |
| 140 | INIT_LIST_HEAD(&msq->q_messages); |
| 141 | INIT_LIST_HEAD(&msq->q_receivers); |
| 142 | INIT_LIST_HEAD(&msq->q_senders); |
| 143 | |
| 144 | /* ipc_addid() locks msq upon success. */ |
| 145 | id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); |
| 146 | if (id < 0) { |
| 147 | ipc_rcu_putref(msq, msg_rcu_free); |
| 148 | return id; |
| 149 | } |
| 150 | |
| 151 | ipc_unlock_object(&msq->q_perm); |
| 152 | rcu_read_unlock(); |
| 153 | |
| 154 | return msq->q_perm.id; |
| 155 | } |
| 156 | |
| 157 | static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz) |
| 158 | { |
| 159 | return msgsz + msq->q_cbytes <= msq->q_qbytes && |
| 160 | 1 + msq->q_qnum <= msq->q_qbytes; |
| 161 | } |
| 162 | |
| 163 | static inline void ss_add(struct msg_queue *msq, |
| 164 | struct msg_sender *mss, size_t msgsz) |
| 165 | { |
| 166 | mss->tsk = current; |
| 167 | mss->msgsz = msgsz; |
| 168 | __set_current_state(TASK_INTERRUPTIBLE); |
| 169 | list_add_tail(&mss->list, &msq->q_senders); |
| 170 | } |
| 171 | |
| 172 | static inline void ss_del(struct msg_sender *mss) |
| 173 | { |
| 174 | if (mss->list.next) |
| 175 | list_del(&mss->list); |
| 176 | } |
| 177 | |
| 178 | static void ss_wakeup(struct msg_queue *msq, |
| 179 | struct wake_q_head *wake_q, bool kill) |
| 180 | { |
| 181 | struct msg_sender *mss, *t; |
| 182 | struct task_struct *stop_tsk = NULL; |
| 183 | struct list_head *h = &msq->q_senders; |
| 184 | |
| 185 | list_for_each_entry_safe(mss, t, h, list) { |
| 186 | if (kill) |
| 187 | mss->list.next = NULL; |
| 188 | |
| 189 | /* |
| 190 | * Stop at the first task we don't wakeup, |
| 191 | * we've already iterated the original |
| 192 | * sender queue. |
| 193 | */ |
| 194 | else if (stop_tsk == mss->tsk) |
| 195 | break; |
| 196 | /* |
| 197 | * We are not in an EIDRM scenario here, therefore |
| 198 | * verify that we really need to wakeup the task. |
| 199 | * To maintain current semantics and wakeup order, |
| 200 | * move the sender to the tail on behalf of the |
| 201 | * blocked task. |
| 202 | */ |
| 203 | else if (!msg_fits_inqueue(msq, mss->msgsz)) { |
| 204 | if (!stop_tsk) |
| 205 | stop_tsk = mss->tsk; |
| 206 | |
| 207 | list_move_tail(&mss->list, &msq->q_senders); |
| 208 | continue; |
| 209 | } |
| 210 | |
| 211 | wake_q_add(wake_q, mss->tsk); |
| 212 | } |
| 213 | } |
| 214 | |
| 215 | static void expunge_all(struct msg_queue *msq, int res, |
| 216 | struct wake_q_head *wake_q) |
| 217 | { |
| 218 | struct msg_receiver *msr, *t; |
| 219 | |
| 220 | list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { |
| 221 | wake_q_add(wake_q, msr->r_tsk); |
| 222 | WRITE_ONCE(msr->r_msg, ERR_PTR(res)); |
| 223 | } |
| 224 | } |
| 225 | |
| 226 | /* |
| 227 | * freeque() wakes up waiters on the sender and receiver waiting queue, |
| 228 | * removes the message queue from message queue ID IDR, and cleans up all the |
| 229 | * messages associated with this queue. |
| 230 | * |
| 231 | * msg_ids.rwsem (writer) and the spinlock for this message queue are held |
| 232 | * before freeque() is called. msg_ids.rwsem remains locked on exit. |
| 233 | */ |
| 234 | static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) |
| 235 | { |
| 236 | struct msg_msg *msg, *t; |
| 237 | struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); |
| 238 | WAKE_Q(wake_q); |
| 239 | |
| 240 | expunge_all(msq, -EIDRM, &wake_q); |
| 241 | ss_wakeup(msq, &wake_q, true); |
| 242 | msg_rmid(ns, msq); |
| 243 | ipc_unlock_object(&msq->q_perm); |
| 244 | wake_up_q(&wake_q); |
| 245 | rcu_read_unlock(); |
| 246 | |
| 247 | list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) { |
| 248 | atomic_dec(&ns->msg_hdrs); |
| 249 | free_msg(msg); |
| 250 | } |
| 251 | atomic_sub(msq->q_cbytes, &ns->msg_bytes); |
| 252 | ipc_rcu_putref(msq, msg_rcu_free); |
| 253 | } |
| 254 | |
| 255 | /* |
| 256 | * Called with msg_ids.rwsem and ipcp locked. |
| 257 | */ |
| 258 | static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg) |
| 259 | { |
| 260 | struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); |
| 261 | |
| 262 | return security_msg_queue_associate(msq, msgflg); |
| 263 | } |
| 264 | |
| 265 | SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg) |
| 266 | { |
| 267 | struct ipc_namespace *ns; |
| 268 | static const struct ipc_ops msg_ops = { |
| 269 | .getnew = newque, |
| 270 | .associate = msg_security, |
| 271 | }; |
| 272 | struct ipc_params msg_params; |
| 273 | |
| 274 | ns = current->nsproxy->ipc_ns; |
| 275 | |
| 276 | msg_params.key = key; |
| 277 | msg_params.flg = msgflg; |
| 278 | |
| 279 | return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params); |
| 280 | } |
| 281 | |
| 282 | static inline unsigned long |
| 283 | copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) |
| 284 | { |
| 285 | switch (version) { |
| 286 | case IPC_64: |
| 287 | return copy_to_user(buf, in, sizeof(*in)); |
| 288 | case IPC_OLD: |
| 289 | { |
| 290 | struct msqid_ds out; |
| 291 | |
| 292 | memset(&out, 0, sizeof(out)); |
| 293 | |
| 294 | ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm); |
| 295 | |
| 296 | out.msg_stime = in->msg_stime; |
| 297 | out.msg_rtime = in->msg_rtime; |
| 298 | out.msg_ctime = in->msg_ctime; |
| 299 | |
| 300 | if (in->msg_cbytes > USHRT_MAX) |
| 301 | out.msg_cbytes = USHRT_MAX; |
| 302 | else |
| 303 | out.msg_cbytes = in->msg_cbytes; |
| 304 | out.msg_lcbytes = in->msg_cbytes; |
| 305 | |
| 306 | if (in->msg_qnum > USHRT_MAX) |
| 307 | out.msg_qnum = USHRT_MAX; |
| 308 | else |
| 309 | out.msg_qnum = in->msg_qnum; |
| 310 | |
| 311 | if (in->msg_qbytes > USHRT_MAX) |
| 312 | out.msg_qbytes = USHRT_MAX; |
| 313 | else |
| 314 | out.msg_qbytes = in->msg_qbytes; |
| 315 | out.msg_lqbytes = in->msg_qbytes; |
| 316 | |
| 317 | out.msg_lspid = in->msg_lspid; |
| 318 | out.msg_lrpid = in->msg_lrpid; |
| 319 | |
| 320 | return copy_to_user(buf, &out, sizeof(out)); |
| 321 | } |
| 322 | default: |
| 323 | return -EINVAL; |
| 324 | } |
| 325 | } |
| 326 | |
| 327 | static inline unsigned long |
| 328 | copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version) |
| 329 | { |
| 330 | switch (version) { |
| 331 | case IPC_64: |
| 332 | if (copy_from_user(out, buf, sizeof(*out))) |
| 333 | return -EFAULT; |
| 334 | return 0; |
| 335 | case IPC_OLD: |
| 336 | { |
| 337 | struct msqid_ds tbuf_old; |
| 338 | |
| 339 | if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) |
| 340 | return -EFAULT; |
| 341 | |
| 342 | out->msg_perm.uid = tbuf_old.msg_perm.uid; |
| 343 | out->msg_perm.gid = tbuf_old.msg_perm.gid; |
| 344 | out->msg_perm.mode = tbuf_old.msg_perm.mode; |
| 345 | |
| 346 | if (tbuf_old.msg_qbytes == 0) |
| 347 | out->msg_qbytes = tbuf_old.msg_lqbytes; |
| 348 | else |
| 349 | out->msg_qbytes = tbuf_old.msg_qbytes; |
| 350 | |
| 351 | return 0; |
| 352 | } |
| 353 | default: |
| 354 | return -EINVAL; |
| 355 | } |
| 356 | } |
| 357 | |
| 358 | /* |
| 359 | * This function handles some msgctl commands which require the rwsem |
| 360 | * to be held in write mode. |
| 361 | * NOTE: no locks must be held, the rwsem is taken inside this function. |
| 362 | */ |
| 363 | static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, |
| 364 | struct msqid_ds __user *buf, int version) |
| 365 | { |
| 366 | struct kern_ipc_perm *ipcp; |
| 367 | struct msqid64_ds uninitialized_var(msqid64); |
| 368 | struct msg_queue *msq; |
| 369 | int err; |
| 370 | |
| 371 | if (cmd == IPC_SET) { |
| 372 | if (copy_msqid_from_user(&msqid64, buf, version)) |
| 373 | return -EFAULT; |
| 374 | } |
| 375 | |
| 376 | down_write(&msg_ids(ns).rwsem); |
| 377 | rcu_read_lock(); |
| 378 | |
| 379 | ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd, |
| 380 | &msqid64.msg_perm, msqid64.msg_qbytes); |
| 381 | if (IS_ERR(ipcp)) { |
| 382 | err = PTR_ERR(ipcp); |
| 383 | goto out_unlock1; |
| 384 | } |
| 385 | |
| 386 | msq = container_of(ipcp, struct msg_queue, q_perm); |
| 387 | |
| 388 | err = security_msg_queue_msgctl(msq, cmd); |
| 389 | if (err) |
| 390 | goto out_unlock1; |
| 391 | |
| 392 | switch (cmd) { |
| 393 | case IPC_RMID: |
| 394 | ipc_lock_object(&msq->q_perm); |
| 395 | /* freeque unlocks the ipc object and rcu */ |
| 396 | freeque(ns, ipcp); |
| 397 | goto out_up; |
| 398 | case IPC_SET: |
| 399 | { |
| 400 | WAKE_Q(wake_q); |
| 401 | |
| 402 | if (msqid64.msg_qbytes > ns->msg_ctlmnb && |
| 403 | !capable(CAP_SYS_RESOURCE)) { |
| 404 | err = -EPERM; |
| 405 | goto out_unlock1; |
| 406 | } |
| 407 | |
| 408 | ipc_lock_object(&msq->q_perm); |
| 409 | err = ipc_update_perm(&msqid64.msg_perm, ipcp); |
| 410 | if (err) |
| 411 | goto out_unlock0; |
| 412 | |
| 413 | msq->q_qbytes = msqid64.msg_qbytes; |
| 414 | |
| 415 | msq->q_ctime = get_seconds(); |
| 416 | /* |
| 417 | * Sleeping receivers might be excluded by |
| 418 | * stricter permissions. |
| 419 | */ |
| 420 | expunge_all(msq, -EAGAIN, &wake_q); |
| 421 | /* |
| 422 | * Sleeping senders might be able to send |
| 423 | * due to a larger queue size. |
| 424 | */ |
| 425 | ss_wakeup(msq, &wake_q, false); |
| 426 | ipc_unlock_object(&msq->q_perm); |
| 427 | wake_up_q(&wake_q); |
| 428 | |
| 429 | goto out_unlock1; |
| 430 | } |
| 431 | default: |
| 432 | err = -EINVAL; |
| 433 | goto out_unlock1; |
| 434 | } |
| 435 | |
| 436 | out_unlock0: |
| 437 | ipc_unlock_object(&msq->q_perm); |
| 438 | out_unlock1: |
| 439 | rcu_read_unlock(); |
| 440 | out_up: |
| 441 | up_write(&msg_ids(ns).rwsem); |
| 442 | return err; |
| 443 | } |
| 444 | |
| 445 | static int msgctl_nolock(struct ipc_namespace *ns, int msqid, |
| 446 | int cmd, int version, void __user *buf) |
| 447 | { |
| 448 | int err; |
| 449 | struct msg_queue *msq; |
| 450 | |
| 451 | switch (cmd) { |
| 452 | case IPC_INFO: |
| 453 | case MSG_INFO: |
| 454 | { |
| 455 | struct msginfo msginfo; |
| 456 | int max_id; |
| 457 | |
| 458 | if (!buf) |
| 459 | return -EFAULT; |
| 460 | |
| 461 | /* |
| 462 | * We must not return kernel stack data. |
| 463 | * due to padding, it's not enough |
| 464 | * to set all member fields. |
| 465 | */ |
| 466 | err = security_msg_queue_msgctl(NULL, cmd); |
| 467 | if (err) |
| 468 | return err; |
| 469 | |
| 470 | memset(&msginfo, 0, sizeof(msginfo)); |
| 471 | msginfo.msgmni = ns->msg_ctlmni; |
| 472 | msginfo.msgmax = ns->msg_ctlmax; |
| 473 | msginfo.msgmnb = ns->msg_ctlmnb; |
| 474 | msginfo.msgssz = MSGSSZ; |
| 475 | msginfo.msgseg = MSGSEG; |
| 476 | down_read(&msg_ids(ns).rwsem); |
| 477 | if (cmd == MSG_INFO) { |
| 478 | msginfo.msgpool = msg_ids(ns).in_use; |
| 479 | msginfo.msgmap = atomic_read(&ns->msg_hdrs); |
| 480 | msginfo.msgtql = atomic_read(&ns->msg_bytes); |
| 481 | } else { |
| 482 | msginfo.msgmap = MSGMAP; |
| 483 | msginfo.msgpool = MSGPOOL; |
| 484 | msginfo.msgtql = MSGTQL; |
| 485 | } |
| 486 | max_id = ipc_get_maxid(&msg_ids(ns)); |
| 487 | up_read(&msg_ids(ns).rwsem); |
| 488 | if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) |
| 489 | return -EFAULT; |
| 490 | return (max_id < 0) ? 0 : max_id; |
| 491 | } |
| 492 | |
| 493 | case MSG_STAT: |
| 494 | case IPC_STAT: |
| 495 | { |
| 496 | struct msqid64_ds tbuf; |
| 497 | int success_return; |
| 498 | |
| 499 | if (!buf) |
| 500 | return -EFAULT; |
| 501 | |
| 502 | memset(&tbuf, 0, sizeof(tbuf)); |
| 503 | |
| 504 | rcu_read_lock(); |
| 505 | if (cmd == MSG_STAT) { |
| 506 | msq = msq_obtain_object(ns, msqid); |
| 507 | if (IS_ERR(msq)) { |
| 508 | err = PTR_ERR(msq); |
| 509 | goto out_unlock; |
| 510 | } |
| 511 | success_return = msq->q_perm.id; |
| 512 | } else { |
| 513 | msq = msq_obtain_object_check(ns, msqid); |
| 514 | if (IS_ERR(msq)) { |
| 515 | err = PTR_ERR(msq); |
| 516 | goto out_unlock; |
| 517 | } |
| 518 | success_return = 0; |
| 519 | } |
| 520 | |
| 521 | err = -EACCES; |
| 522 | if (ipcperms(ns, &msq->q_perm, S_IRUGO)) |
| 523 | goto out_unlock; |
| 524 | |
| 525 | err = security_msg_queue_msgctl(msq, cmd); |
| 526 | if (err) |
| 527 | goto out_unlock; |
| 528 | |
| 529 | kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); |
| 530 | tbuf.msg_stime = msq->q_stime; |
| 531 | tbuf.msg_rtime = msq->q_rtime; |
| 532 | tbuf.msg_ctime = msq->q_ctime; |
| 533 | tbuf.msg_cbytes = msq->q_cbytes; |
| 534 | tbuf.msg_qnum = msq->q_qnum; |
| 535 | tbuf.msg_qbytes = msq->q_qbytes; |
| 536 | tbuf.msg_lspid = msq->q_lspid; |
| 537 | tbuf.msg_lrpid = msq->q_lrpid; |
| 538 | rcu_read_unlock(); |
| 539 | |
| 540 | if (copy_msqid_to_user(buf, &tbuf, version)) |
| 541 | return -EFAULT; |
| 542 | return success_return; |
| 543 | } |
| 544 | |
| 545 | default: |
| 546 | return -EINVAL; |
| 547 | } |
| 548 | |
| 549 | return err; |
| 550 | out_unlock: |
| 551 | rcu_read_unlock(); |
| 552 | return err; |
| 553 | } |
| 554 | |
| 555 | SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) |
| 556 | { |
| 557 | int version; |
| 558 | struct ipc_namespace *ns; |
| 559 | |
| 560 | if (msqid < 0 || cmd < 0) |
| 561 | return -EINVAL; |
| 562 | |
| 563 | version = ipc_parse_version(&cmd); |
| 564 | ns = current->nsproxy->ipc_ns; |
| 565 | |
| 566 | switch (cmd) { |
| 567 | case IPC_INFO: |
| 568 | case MSG_INFO: |
| 569 | case MSG_STAT: /* msqid is an index rather than a msg queue id */ |
| 570 | case IPC_STAT: |
| 571 | return msgctl_nolock(ns, msqid, cmd, version, buf); |
| 572 | case IPC_SET: |
| 573 | case IPC_RMID: |
| 574 | return msgctl_down(ns, msqid, cmd, buf, version); |
| 575 | default: |
| 576 | return -EINVAL; |
| 577 | } |
| 578 | } |
| 579 | |
| 580 | static int testmsg(struct msg_msg *msg, long type, int mode) |
| 581 | { |
| 582 | switch (mode) { |
| 583 | case SEARCH_ANY: |
| 584 | case SEARCH_NUMBER: |
| 585 | return 1; |
| 586 | case SEARCH_LESSEQUAL: |
| 587 | if (msg->m_type <= type) |
| 588 | return 1; |
| 589 | break; |
| 590 | case SEARCH_EQUAL: |
| 591 | if (msg->m_type == type) |
| 592 | return 1; |
| 593 | break; |
| 594 | case SEARCH_NOTEQUAL: |
| 595 | if (msg->m_type != type) |
| 596 | return 1; |
| 597 | break; |
| 598 | } |
| 599 | return 0; |
| 600 | } |
| 601 | |
| 602 | static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg, |
| 603 | struct wake_q_head *wake_q) |
| 604 | { |
| 605 | struct msg_receiver *msr, *t; |
| 606 | |
| 607 | list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { |
| 608 | if (testmsg(msg, msr->r_msgtype, msr->r_mode) && |
| 609 | !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, |
| 610 | msr->r_msgtype, msr->r_mode)) { |
| 611 | |
| 612 | list_del(&msr->r_list); |
| 613 | if (msr->r_maxsize < msg->m_ts) { |
| 614 | wake_q_add(wake_q, msr->r_tsk); |
| 615 | WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG)); |
| 616 | } else { |
| 617 | msq->q_lrpid = task_pid_vnr(msr->r_tsk); |
| 618 | msq->q_rtime = get_seconds(); |
| 619 | |
| 620 | wake_q_add(wake_q, msr->r_tsk); |
| 621 | WRITE_ONCE(msr->r_msg, msg); |
| 622 | return 1; |
| 623 | } |
| 624 | } |
| 625 | } |
| 626 | |
| 627 | return 0; |
| 628 | } |
| 629 | |
| 630 | long do_msgsnd(int msqid, long mtype, void __user *mtext, |
| 631 | size_t msgsz, int msgflg) |
| 632 | { |
| 633 | struct msg_queue *msq; |
| 634 | struct msg_msg *msg; |
| 635 | int err; |
| 636 | struct ipc_namespace *ns; |
| 637 | WAKE_Q(wake_q); |
| 638 | |
| 639 | ns = current->nsproxy->ipc_ns; |
| 640 | |
| 641 | if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0) |
| 642 | return -EINVAL; |
| 643 | if (mtype < 1) |
| 644 | return -EINVAL; |
| 645 | |
| 646 | msg = load_msg(mtext, msgsz); |
| 647 | if (IS_ERR(msg)) |
| 648 | return PTR_ERR(msg); |
| 649 | |
| 650 | msg->m_type = mtype; |
| 651 | msg->m_ts = msgsz; |
| 652 | |
| 653 | rcu_read_lock(); |
| 654 | msq = msq_obtain_object_check(ns, msqid); |
| 655 | if (IS_ERR(msq)) { |
| 656 | err = PTR_ERR(msq); |
| 657 | goto out_unlock1; |
| 658 | } |
| 659 | |
| 660 | for (;;) { |
| 661 | struct msg_sender s; |
| 662 | |
| 663 | err = -EACCES; |
| 664 | if (ipcperms(ns, &msq->q_perm, S_IWUGO)) |
| 665 | goto out_unlock1; |
| 666 | |
| 667 | ipc_lock_object(&msq->q_perm); |
| 668 | |
| 669 | /* raced with RMID? */ |
| 670 | if (!ipc_valid_object(&msq->q_perm)) { |
| 671 | err = -EIDRM; |
| 672 | goto out_unlock0; |
| 673 | } |
| 674 | |
| 675 | err = security_msg_queue_msgsnd(msq, msg, msgflg); |
| 676 | if (err) |
| 677 | goto out_unlock0; |
| 678 | |
| 679 | if (msg_fits_inqueue(msq, msgsz)) |
| 680 | break; |
| 681 | |
| 682 | /* queue full, wait: */ |
| 683 | if (msgflg & IPC_NOWAIT) { |
| 684 | err = -EAGAIN; |
| 685 | goto out_unlock0; |
| 686 | } |
| 687 | |
| 688 | /* enqueue the sender and prepare to block */ |
| 689 | ss_add(msq, &s, msgsz); |
| 690 | |
| 691 | if (!ipc_rcu_getref(msq)) { |
| 692 | err = -EIDRM; |
| 693 | goto out_unlock0; |
| 694 | } |
| 695 | |
| 696 | ipc_unlock_object(&msq->q_perm); |
| 697 | rcu_read_unlock(); |
| 698 | schedule(); |
| 699 | |
| 700 | rcu_read_lock(); |
| 701 | ipc_lock_object(&msq->q_perm); |
| 702 | |
| 703 | ipc_rcu_putref(msq, msg_rcu_free); |
| 704 | /* raced with RMID? */ |
| 705 | if (!ipc_valid_object(&msq->q_perm)) { |
| 706 | err = -EIDRM; |
| 707 | goto out_unlock0; |
| 708 | } |
| 709 | ss_del(&s); |
| 710 | |
| 711 | if (signal_pending(current)) { |
| 712 | err = -ERESTARTNOHAND; |
| 713 | goto out_unlock0; |
| 714 | } |
| 715 | |
| 716 | ipc_unlock_object(&msq->q_perm); |
| 717 | } |
| 718 | |
| 719 | msq->q_lspid = task_tgid_vnr(current); |
| 720 | msq->q_stime = get_seconds(); |
| 721 | |
| 722 | if (!pipelined_send(msq, msg, &wake_q)) { |
| 723 | /* no one is waiting for this message, enqueue it */ |
| 724 | list_add_tail(&msg->m_list, &msq->q_messages); |
| 725 | msq->q_cbytes += msgsz; |
| 726 | msq->q_qnum++; |
| 727 | atomic_add(msgsz, &ns->msg_bytes); |
| 728 | atomic_inc(&ns->msg_hdrs); |
| 729 | } |
| 730 | |
| 731 | err = 0; |
| 732 | msg = NULL; |
| 733 | |
| 734 | out_unlock0: |
| 735 | ipc_unlock_object(&msq->q_perm); |
| 736 | wake_up_q(&wake_q); |
| 737 | out_unlock1: |
| 738 | rcu_read_unlock(); |
| 739 | if (msg != NULL) |
| 740 | free_msg(msg); |
| 741 | return err; |
| 742 | } |
| 743 | |
| 744 | SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, |
| 745 | int, msgflg) |
| 746 | { |
| 747 | long mtype; |
| 748 | |
| 749 | if (get_user(mtype, &msgp->mtype)) |
| 750 | return -EFAULT; |
| 751 | return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg); |
| 752 | } |
| 753 | |
| 754 | static inline int convert_mode(long *msgtyp, int msgflg) |
| 755 | { |
| 756 | if (msgflg & MSG_COPY) |
| 757 | return SEARCH_NUMBER; |
| 758 | /* |
| 759 | * find message of correct type. |
| 760 | * msgtyp = 0 => get first. |
| 761 | * msgtyp > 0 => get first message of matching type. |
| 762 | * msgtyp < 0 => get message with least type must be < abs(msgtype). |
| 763 | */ |
| 764 | if (*msgtyp == 0) |
| 765 | return SEARCH_ANY; |
| 766 | if (*msgtyp < 0) { |
| 767 | *msgtyp = -*msgtyp; |
| 768 | return SEARCH_LESSEQUAL; |
| 769 | } |
| 770 | if (msgflg & MSG_EXCEPT) |
| 771 | return SEARCH_NOTEQUAL; |
| 772 | return SEARCH_EQUAL; |
| 773 | } |
| 774 | |
| 775 | static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz) |
| 776 | { |
| 777 | struct msgbuf __user *msgp = dest; |
| 778 | size_t msgsz; |
| 779 | |
| 780 | if (put_user(msg->m_type, &msgp->mtype)) |
| 781 | return -EFAULT; |
| 782 | |
| 783 | msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz; |
| 784 | if (store_msg(msgp->mtext, msg, msgsz)) |
| 785 | return -EFAULT; |
| 786 | return msgsz; |
| 787 | } |
| 788 | |
| 789 | #ifdef CONFIG_CHECKPOINT_RESTORE |
| 790 | /* |
| 791 | * This function creates new kernel message structure, large enough to store |
| 792 | * bufsz message bytes. |
| 793 | */ |
| 794 | static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) |
| 795 | { |
| 796 | struct msg_msg *copy; |
| 797 | |
| 798 | /* |
| 799 | * Create dummy message to copy real message to. |
| 800 | */ |
| 801 | copy = load_msg(buf, bufsz); |
| 802 | if (!IS_ERR(copy)) |
| 803 | copy->m_ts = bufsz; |
| 804 | return copy; |
| 805 | } |
| 806 | |
| 807 | static inline void free_copy(struct msg_msg *copy) |
| 808 | { |
| 809 | if (copy) |
| 810 | free_msg(copy); |
| 811 | } |
| 812 | #else |
| 813 | static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) |
| 814 | { |
| 815 | return ERR_PTR(-ENOSYS); |
| 816 | } |
| 817 | |
| 818 | static inline void free_copy(struct msg_msg *copy) |
| 819 | { |
| 820 | } |
| 821 | #endif |
| 822 | |
| 823 | static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) |
| 824 | { |
| 825 | struct msg_msg *msg, *found = NULL; |
| 826 | long count = 0; |
| 827 | |
| 828 | list_for_each_entry(msg, &msq->q_messages, m_list) { |
| 829 | if (testmsg(msg, *msgtyp, mode) && |
| 830 | !security_msg_queue_msgrcv(msq, msg, current, |
| 831 | *msgtyp, mode)) { |
| 832 | if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) { |
| 833 | *msgtyp = msg->m_type - 1; |
| 834 | found = msg; |
| 835 | } else if (mode == SEARCH_NUMBER) { |
| 836 | if (*msgtyp == count) |
| 837 | return msg; |
| 838 | } else |
| 839 | return msg; |
| 840 | count++; |
| 841 | } |
| 842 | } |
| 843 | |
| 844 | return found ?: ERR_PTR(-EAGAIN); |
| 845 | } |
| 846 | |
| 847 | long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg, |
| 848 | long (*msg_handler)(void __user *, struct msg_msg *, size_t)) |
| 849 | { |
| 850 | int mode; |
| 851 | struct msg_queue *msq; |
| 852 | struct ipc_namespace *ns; |
| 853 | struct msg_msg *msg, *copy = NULL; |
| 854 | WAKE_Q(wake_q); |
| 855 | |
| 856 | ns = current->nsproxy->ipc_ns; |
| 857 | |
| 858 | if (msqid < 0 || (long) bufsz < 0) |
| 859 | return -EINVAL; |
| 860 | |
| 861 | if (msgflg & MSG_COPY) { |
| 862 | if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT)) |
| 863 | return -EINVAL; |
| 864 | copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax)); |
| 865 | if (IS_ERR(copy)) |
| 866 | return PTR_ERR(copy); |
| 867 | } |
| 868 | mode = convert_mode(&msgtyp, msgflg); |
| 869 | |
| 870 | rcu_read_lock(); |
| 871 | msq = msq_obtain_object_check(ns, msqid); |
| 872 | if (IS_ERR(msq)) { |
| 873 | rcu_read_unlock(); |
| 874 | free_copy(copy); |
| 875 | return PTR_ERR(msq); |
| 876 | } |
| 877 | |
| 878 | for (;;) { |
| 879 | struct msg_receiver msr_d; |
| 880 | |
| 881 | msg = ERR_PTR(-EACCES); |
| 882 | if (ipcperms(ns, &msq->q_perm, S_IRUGO)) |
| 883 | goto out_unlock1; |
| 884 | |
| 885 | ipc_lock_object(&msq->q_perm); |
| 886 | |
| 887 | /* raced with RMID? */ |
| 888 | if (!ipc_valid_object(&msq->q_perm)) { |
| 889 | msg = ERR_PTR(-EIDRM); |
| 890 | goto out_unlock0; |
| 891 | } |
| 892 | |
| 893 | msg = find_msg(msq, &msgtyp, mode); |
| 894 | if (!IS_ERR(msg)) { |
| 895 | /* |
| 896 | * Found a suitable message. |
| 897 | * Unlink it from the queue. |
| 898 | */ |
| 899 | if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { |
| 900 | msg = ERR_PTR(-E2BIG); |
| 901 | goto out_unlock0; |
| 902 | } |
| 903 | /* |
| 904 | * If we are copying, then do not unlink message and do |
| 905 | * not update queue parameters. |
| 906 | */ |
| 907 | if (msgflg & MSG_COPY) { |
| 908 | msg = copy_msg(msg, copy); |
| 909 | goto out_unlock0; |
| 910 | } |
| 911 | |
| 912 | list_del(&msg->m_list); |
| 913 | msq->q_qnum--; |
| 914 | msq->q_rtime = get_seconds(); |
| 915 | msq->q_lrpid = task_tgid_vnr(current); |
| 916 | msq->q_cbytes -= msg->m_ts; |
| 917 | atomic_sub(msg->m_ts, &ns->msg_bytes); |
| 918 | atomic_dec(&ns->msg_hdrs); |
| 919 | ss_wakeup(msq, &wake_q, false); |
| 920 | |
| 921 | goto out_unlock0; |
| 922 | } |
| 923 | |
| 924 | /* No message waiting. Wait for a message */ |
| 925 | if (msgflg & IPC_NOWAIT) { |
| 926 | msg = ERR_PTR(-ENOMSG); |
| 927 | goto out_unlock0; |
| 928 | } |
| 929 | |
| 930 | list_add_tail(&msr_d.r_list, &msq->q_receivers); |
| 931 | msr_d.r_tsk = current; |
| 932 | msr_d.r_msgtype = msgtyp; |
| 933 | msr_d.r_mode = mode; |
| 934 | if (msgflg & MSG_NOERROR) |
| 935 | msr_d.r_maxsize = INT_MAX; |
| 936 | else |
| 937 | msr_d.r_maxsize = bufsz; |
| 938 | msr_d.r_msg = ERR_PTR(-EAGAIN); |
| 939 | __set_current_state(TASK_INTERRUPTIBLE); |
| 940 | |
| 941 | ipc_unlock_object(&msq->q_perm); |
| 942 | rcu_read_unlock(); |
| 943 | schedule(); |
| 944 | |
| 945 | /* |
| 946 | * Lockless receive, part 1: |
| 947 | * We don't hold a reference to the queue and getting a |
| 948 | * reference would defeat the idea of a lockless operation, |
| 949 | * thus the code relies on rcu to guarantee the existence of |
| 950 | * msq: |
| 951 | * Prior to destruction, expunge_all(-EIRDM) changes r_msg. |
| 952 | * Thus if r_msg is -EAGAIN, then the queue not yet destroyed. |
| 953 | */ |
| 954 | rcu_read_lock(); |
| 955 | |
| 956 | /* |
| 957 | * Lockless receive, part 2: |
| 958 | * The work in pipelined_send() and expunge_all(): |
| 959 | * - Set pointer to message |
| 960 | * - Queue the receiver task for later wakeup |
| 961 | * - Wake up the process after the lock is dropped. |
| 962 | * |
| 963 | * Should the process wake up before this wakeup (due to a |
| 964 | * signal) it will either see the message and continue ... |
| 965 | */ |
| 966 | msg = READ_ONCE(msr_d.r_msg); |
| 967 | if (msg != ERR_PTR(-EAGAIN)) |
| 968 | goto out_unlock1; |
| 969 | |
| 970 | /* |
| 971 | * ... or see -EAGAIN, acquire the lock to check the message |
| 972 | * again. |
| 973 | */ |
| 974 | ipc_lock_object(&msq->q_perm); |
| 975 | |
| 976 | msg = msr_d.r_msg; |
| 977 | if (msg != ERR_PTR(-EAGAIN)) |
| 978 | goto out_unlock0; |
| 979 | |
| 980 | list_del(&msr_d.r_list); |
| 981 | if (signal_pending(current)) { |
| 982 | msg = ERR_PTR(-ERESTARTNOHAND); |
| 983 | goto out_unlock0; |
| 984 | } |
| 985 | |
| 986 | ipc_unlock_object(&msq->q_perm); |
| 987 | } |
| 988 | |
| 989 | out_unlock0: |
| 990 | ipc_unlock_object(&msq->q_perm); |
| 991 | wake_up_q(&wake_q); |
| 992 | out_unlock1: |
| 993 | rcu_read_unlock(); |
| 994 | if (IS_ERR(msg)) { |
| 995 | free_copy(copy); |
| 996 | return PTR_ERR(msg); |
| 997 | } |
| 998 | |
| 999 | bufsz = msg_handler(buf, msg, bufsz); |
| 1000 | free_msg(msg); |
| 1001 | |
| 1002 | return bufsz; |
| 1003 | } |
| 1004 | |
| 1005 | SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, |
| 1006 | long, msgtyp, int, msgflg) |
| 1007 | { |
| 1008 | return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill); |
| 1009 | } |
| 1010 | |
| 1011 | |
| 1012 | void msg_init_ns(struct ipc_namespace *ns) |
| 1013 | { |
| 1014 | ns->msg_ctlmax = MSGMAX; |
| 1015 | ns->msg_ctlmnb = MSGMNB; |
| 1016 | ns->msg_ctlmni = MSGMNI; |
| 1017 | |
| 1018 | atomic_set(&ns->msg_bytes, 0); |
| 1019 | atomic_set(&ns->msg_hdrs, 0); |
| 1020 | ipc_init_ids(&ns->ids[IPC_MSG_IDS]); |
| 1021 | } |
| 1022 | |
| 1023 | #ifdef CONFIG_IPC_NS |
| 1024 | void msg_exit_ns(struct ipc_namespace *ns) |
| 1025 | { |
| 1026 | free_ipcs(ns, &msg_ids(ns), freeque); |
| 1027 | idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr); |
| 1028 | } |
| 1029 | #endif |
| 1030 | |
| 1031 | #ifdef CONFIG_PROC_FS |
| 1032 | static int sysvipc_msg_proc_show(struct seq_file *s, void *it) |
| 1033 | { |
| 1034 | struct user_namespace *user_ns = seq_user_ns(s); |
| 1035 | struct msg_queue *msq = it; |
| 1036 | |
| 1037 | seq_printf(s, |
| 1038 | "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n", |
| 1039 | msq->q_perm.key, |
| 1040 | msq->q_perm.id, |
| 1041 | msq->q_perm.mode, |
| 1042 | msq->q_cbytes, |
| 1043 | msq->q_qnum, |
| 1044 | msq->q_lspid, |
| 1045 | msq->q_lrpid, |
| 1046 | from_kuid_munged(user_ns, msq->q_perm.uid), |
| 1047 | from_kgid_munged(user_ns, msq->q_perm.gid), |
| 1048 | from_kuid_munged(user_ns, msq->q_perm.cuid), |
| 1049 | from_kgid_munged(user_ns, msq->q_perm.cgid), |
| 1050 | msq->q_stime, |
| 1051 | msq->q_rtime, |
| 1052 | msq->q_ctime); |
| 1053 | |
| 1054 | return 0; |
| 1055 | } |
| 1056 | #endif |
| 1057 | |
| 1058 | void __init msg_init(void) |
| 1059 | { |
| 1060 | msg_init_ns(&init_ipc_ns); |
| 1061 | |
| 1062 | ipc_init_proc_interface("sysvipc/msg", |
| 1063 | " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n", |
| 1064 | IPC_MSG_IDS, sysvipc_msg_proc_show); |
| 1065 | } |