blob: cbd27e519943b140a2f291cecbf3e0e89820172a [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/ipc/msg.c
Ingo Molnar5a06a362006-07-30 03:04:11 -07003 * Copyright (C) 1992 Krishna Balasubramanian
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 *
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
Christian Kujau624dffc2006-01-15 02:43:54 +010015 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
Steve Grubb073115d2006-04-02 17:07:33 -040016 *
17 * support for audit of ipc object properties and permission changes
18 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
Kirill Korotaev1e786932006-10-02 02:18:21 -070019 *
20 * namespaces support
21 * OpenVZ, SWsoft Inc.
22 * Pavel Emelianov <xemul@openvz.org>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023 */
24
Randy.Dunlapc59ede72006-01-11 12:17:46 -080025#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/slab.h>
27#include <linux/msg.h>
28#include <linux/spinlock.h>
29#include <linux/init.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>
Mike Waychison19b49462005-09-06 15:17:10 -070036#include <linux/seq_file.h>
Ingo Molnar5f921ae2006-03-26 01:37:17 -080037#include <linux/mutex.h>
Kirill Korotaev1e786932006-10-02 02:18:21 -070038#include <linux/nsproxy.h>
Ingo Molnar5f921ae2006-03-26 01:37:17 -080039
Linus Torvalds1da177e2005-04-16 15:20:36 -070040#include <asm/current.h>
41#include <asm/uaccess.h>
42#include "util.h"
43
Ingo Molnar5a06a362006-07-30 03:04:11 -070044/*
45 * one msg_receiver structure for each sleeping receiver:
46 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070047struct msg_receiver {
Ingo Molnar5a06a362006-07-30 03:04:11 -070048 struct list_head r_list;
49 struct task_struct *r_tsk;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
Ingo Molnar5a06a362006-07-30 03:04:11 -070051 int r_mode;
52 long r_msgtype;
53 long r_maxsize;
Linus Torvalds1da177e2005-04-16 15:20:36 -070054
Linus Torvalds80491eb2006-11-04 09:55:00 -080055 struct msg_msg *volatile r_msg;
Linus Torvalds1da177e2005-04-16 15:20:36 -070056};
57
58/* one msg_sender for each sleeping sender */
59struct msg_sender {
Ingo Molnar5a06a362006-07-30 03:04:11 -070060 struct list_head list;
61 struct task_struct *tsk;
Linus Torvalds1da177e2005-04-16 15:20:36 -070062};
63
64#define SEARCH_ANY 1
65#define SEARCH_EQUAL 2
66#define SEARCH_NOTEQUAL 3
67#define SEARCH_LESSEQUAL 4
68
Ingo Molnar5a06a362006-07-30 03:04:11 -070069static atomic_t msg_bytes = ATOMIC_INIT(0);
70static atomic_t msg_hdrs = ATOMIC_INIT(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -070071
Kirill Korotaev1e786932006-10-02 02:18:21 -070072static struct ipc_ids init_msg_ids;
Linus Torvalds1da177e2005-04-16 15:20:36 -070073
Kirill Korotaev1e786932006-10-02 02:18:21 -070074#define msg_ids(ns) (*((ns)->ids[IPC_MSG_IDS]))
75
76#define msg_lock(ns, id) ((struct msg_queue*)ipc_lock(&msg_ids(ns), id))
Ingo Molnar5a06a362006-07-30 03:04:11 -070077#define msg_unlock(msq) ipc_unlock(&(msq)->q_perm)
Kirill Korotaev1e786932006-10-02 02:18:21 -070078#define msg_rmid(ns, id) ((struct msg_queue*)ipc_rmid(&msg_ids(ns), id))
79#define msg_checkid(ns, msq, msgid) \
80 ipc_checkid(&msg_ids(ns), &msq->q_perm, msgid)
81#define msg_buildid(ns, id, seq) \
82 ipc_buildid(&msg_ids(ns), id, seq)
Linus Torvalds1da177e2005-04-16 15:20:36 -070083
Kirill Korotaev1e786932006-10-02 02:18:21 -070084static void freeque (struct ipc_namespace *ns, struct msg_queue *msq, int id);
85static int newque (struct ipc_namespace *ns, key_t key, int msgflg);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -070087static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088#endif
89
Cedric Le Goater7d69a1f2007-07-15 23:40:58 -070090static void __msg_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
Linus Torvalds1da177e2005-04-16 15:20:36 -070091{
Kirill Korotaev1e786932006-10-02 02:18:21 -070092 ns->ids[IPC_MSG_IDS] = ids;
93 ns->msg_ctlmax = MSGMAX;
94 ns->msg_ctlmnb = MSGMNB;
95 ns->msg_ctlmni = MSGMNI;
96 ipc_init_ids(ids, ns->msg_ctlmni);
Linus Torvalds1da177e2005-04-16 15:20:36 -070097}
98
Kirill Korotaev1e786932006-10-02 02:18:21 -070099int msg_init_ns(struct ipc_namespace *ns)
100{
101 struct ipc_ids *ids;
102
103 ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
104 if (ids == NULL)
105 return -ENOMEM;
106
107 __msg_init_ns(ns, ids);
108 return 0;
109}
110
111void msg_exit_ns(struct ipc_namespace *ns)
112{
113 int i;
114 struct msg_queue *msq;
115
116 mutex_lock(&msg_ids(ns).mutex);
117 for (i = 0; i <= msg_ids(ns).max_id; i++) {
118 msq = msg_lock(ns, i);
119 if (msq == NULL)
120 continue;
121
122 freeque(ns, msq, i);
123 }
124 mutex_unlock(&msg_ids(ns).mutex);
125
Pavel Emelianovc7e12b82006-11-02 22:07:03 -0800126 ipc_fini_ids(ns->ids[IPC_MSG_IDS]);
Kirill Korotaev1e786932006-10-02 02:18:21 -0700127 kfree(ns->ids[IPC_MSG_IDS]);
128 ns->ids[IPC_MSG_IDS] = NULL;
129}
Kirill Korotaev1e786932006-10-02 02:18:21 -0700130
131void __init msg_init(void)
132{
133 __msg_init_ns(&init_ipc_ns, &init_msg_ids);
134 ipc_init_proc_interface("sysvipc/msg",
135 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
136 IPC_MSG_IDS, sysvipc_msg_proc_show);
137}
138
139static int newque (struct ipc_namespace *ns, key_t key, int msgflg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 struct msg_queue *msq;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700142 int id, retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
Ingo Molnar5a06a362006-07-30 03:04:11 -0700144 msq = ipc_rcu_alloc(sizeof(*msq));
145 if (!msq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 return -ENOMEM;
147
Ingo Molnar5a06a362006-07-30 03:04:11 -0700148 msq->q_perm.mode = msgflg & S_IRWXUGO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 msq->q_perm.key = key;
150
151 msq->q_perm.security = NULL;
152 retval = security_msg_queue_alloc(msq);
153 if (retval) {
154 ipc_rcu_putref(msq);
155 return retval;
156 }
157
Kirill Korotaev1e786932006-10-02 02:18:21 -0700158 id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700159 if (id == -1) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 security_msg_queue_free(msq);
161 ipc_rcu_putref(msq);
162 return -ENOSPC;
163 }
164
Kirill Korotaev1e786932006-10-02 02:18:21 -0700165 msq->q_id = msg_buildid(ns, id, msq->q_perm.seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 msq->q_stime = msq->q_rtime = 0;
167 msq->q_ctime = get_seconds();
168 msq->q_cbytes = msq->q_qnum = 0;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700169 msq->q_qbytes = ns->msg_ctlmnb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 msq->q_lspid = msq->q_lrpid = 0;
171 INIT_LIST_HEAD(&msq->q_messages);
172 INIT_LIST_HEAD(&msq->q_receivers);
173 INIT_LIST_HEAD(&msq->q_senders);
174 msg_unlock(msq);
175
Mike Waychison19b49462005-09-06 15:17:10 -0700176 return msq->q_id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177}
178
Ingo Molnar5a06a362006-07-30 03:04:11 -0700179static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180{
Ingo Molnar5a06a362006-07-30 03:04:11 -0700181 mss->tsk = current;
182 current->state = TASK_INTERRUPTIBLE;
183 list_add_tail(&mss->list, &msq->q_senders);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184}
185
Ingo Molnar5a06a362006-07-30 03:04:11 -0700186static inline void ss_del(struct msg_sender *mss)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187{
Ingo Molnar5a06a362006-07-30 03:04:11 -0700188 if (mss->list.next != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 list_del(&mss->list);
190}
191
Ingo Molnar5a06a362006-07-30 03:04:11 -0700192static void ss_wakeup(struct list_head *h, int kill)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193{
194 struct list_head *tmp;
195
196 tmp = h->next;
197 while (tmp != h) {
Ingo Molnar5a06a362006-07-30 03:04:11 -0700198 struct msg_sender *mss;
199
200 mss = list_entry(tmp, struct msg_sender, list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 tmp = tmp->next;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700202 if (kill)
203 mss->list.next = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 wake_up_process(mss->tsk);
205 }
206}
207
Ingo Molnar5a06a362006-07-30 03:04:11 -0700208static void expunge_all(struct msg_queue *msq, int res)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209{
210 struct list_head *tmp;
211
212 tmp = msq->q_receivers.next;
213 while (tmp != &msq->q_receivers) {
Ingo Molnar5a06a362006-07-30 03:04:11 -0700214 struct msg_receiver *msr;
215
216 msr = list_entry(tmp, struct msg_receiver, r_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 tmp = tmp->next;
218 msr->r_msg = NULL;
219 wake_up_process(msr->r_tsk);
220 smp_mb();
221 msr->r_msg = ERR_PTR(res);
222 }
223}
Ingo Molnar5a06a362006-07-30 03:04:11 -0700224
225/*
226 * freeque() wakes up waiters on the sender and receiver waiting queue,
227 * removes the message queue from message queue ID
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 * array, and cleans up all the messages associated with this queue.
229 *
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800230 * msg_ids.mutex and the spinlock for this message queue is hold
231 * before freeque() is called. msg_ids.mutex remains locked on exit.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 */
Kirill Korotaev1e786932006-10-02 02:18:21 -0700233static void freeque(struct ipc_namespace *ns, struct msg_queue *msq, int id)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234{
235 struct list_head *tmp;
236
Ingo Molnar5a06a362006-07-30 03:04:11 -0700237 expunge_all(msq, -EIDRM);
238 ss_wakeup(&msq->q_senders, 1);
Kirill Korotaev1e786932006-10-02 02:18:21 -0700239 msq = msg_rmid(ns, id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 msg_unlock(msq);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700241
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 tmp = msq->q_messages.next;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700243 while (tmp != &msq->q_messages) {
244 struct msg_msg *msg = list_entry(tmp, struct msg_msg, m_list);
245
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 tmp = tmp->next;
247 atomic_dec(&msg_hdrs);
248 free_msg(msg);
249 }
250 atomic_sub(msq->q_cbytes, &msg_bytes);
251 security_msg_queue_free(msq);
252 ipc_rcu_putref(msq);
253}
254
Ingo Molnar5a06a362006-07-30 03:04:11 -0700255asmlinkage long sys_msgget(key_t key, int msgflg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 struct msg_queue *msq;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700258 int id, ret = -EPERM;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700259 struct ipc_namespace *ns;
260
261 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262
Kirill Korotaev1e786932006-10-02 02:18:21 -0700263 mutex_lock(&msg_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 if (key == IPC_PRIVATE)
Kirill Korotaev1e786932006-10-02 02:18:21 -0700265 ret = newque(ns, key, msgflg);
266 else if ((id = ipc_findkey(&msg_ids(ns), key)) == -1) { /* key not used */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 if (!(msgflg & IPC_CREAT))
268 ret = -ENOENT;
269 else
Kirill Korotaev1e786932006-10-02 02:18:21 -0700270 ret = newque(ns, key, msgflg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 } else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) {
272 ret = -EEXIST;
273 } else {
Kirill Korotaev1e786932006-10-02 02:18:21 -0700274 msq = msg_lock(ns, id);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700275 BUG_ON(msq == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 if (ipcperms(&msq->q_perm, msgflg))
277 ret = -EACCES;
278 else {
Kirill Korotaev1e786932006-10-02 02:18:21 -0700279 int qid = msg_buildid(ns, id, msq->q_perm.seq);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700280
281 ret = security_msg_queue_associate(msq, msgflg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 if (!ret)
283 ret = qid;
284 }
285 msg_unlock(msq);
286 }
Kirill Korotaev1e786932006-10-02 02:18:21 -0700287 mutex_unlock(&msg_ids(ns).mutex);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700288
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 return ret;
290}
291
Ingo Molnar5a06a362006-07-30 03:04:11 -0700292static inline unsigned long
293copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294{
295 switch(version) {
296 case IPC_64:
Ingo Molnar5a06a362006-07-30 03:04:11 -0700297 return copy_to_user(buf, in, sizeof(*in));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 case IPC_OLD:
Ingo Molnar5a06a362006-07-30 03:04:11 -0700299 {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 struct msqid_ds out;
301
Ingo Molnar5a06a362006-07-30 03:04:11 -0700302 memset(&out, 0, sizeof(out));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303
304 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
305
306 out.msg_stime = in->msg_stime;
307 out.msg_rtime = in->msg_rtime;
308 out.msg_ctime = in->msg_ctime;
309
Ingo Molnar5a06a362006-07-30 03:04:11 -0700310 if (in->msg_cbytes > USHRT_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 out.msg_cbytes = USHRT_MAX;
312 else
313 out.msg_cbytes = in->msg_cbytes;
314 out.msg_lcbytes = in->msg_cbytes;
315
Ingo Molnar5a06a362006-07-30 03:04:11 -0700316 if (in->msg_qnum > USHRT_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 out.msg_qnum = USHRT_MAX;
318 else
319 out.msg_qnum = in->msg_qnum;
320
Ingo Molnar5a06a362006-07-30 03:04:11 -0700321 if (in->msg_qbytes > USHRT_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 out.msg_qbytes = USHRT_MAX;
323 else
324 out.msg_qbytes = in->msg_qbytes;
325 out.msg_lqbytes = in->msg_qbytes;
326
327 out.msg_lspid = in->msg_lspid;
328 out.msg_lrpid = in->msg_lrpid;
329
Ingo Molnar5a06a362006-07-30 03:04:11 -0700330 return copy_to_user(buf, &out, sizeof(out));
331 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 default:
333 return -EINVAL;
334 }
335}
336
337struct msq_setbuf {
338 unsigned long qbytes;
339 uid_t uid;
340 gid_t gid;
341 mode_t mode;
342};
343
Ingo Molnar5a06a362006-07-30 03:04:11 -0700344static inline unsigned long
345copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346{
347 switch(version) {
348 case IPC_64:
Ingo Molnar5a06a362006-07-30 03:04:11 -0700349 {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 struct msqid64_ds tbuf;
351
Ingo Molnar5a06a362006-07-30 03:04:11 -0700352 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 return -EFAULT;
354
355 out->qbytes = tbuf.msg_qbytes;
356 out->uid = tbuf.msg_perm.uid;
357 out->gid = tbuf.msg_perm.gid;
358 out->mode = tbuf.msg_perm.mode;
359
360 return 0;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700361 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 case IPC_OLD:
Ingo Molnar5a06a362006-07-30 03:04:11 -0700363 {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 struct msqid_ds tbuf_old;
365
Ingo Molnar5a06a362006-07-30 03:04:11 -0700366 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 return -EFAULT;
368
369 out->uid = tbuf_old.msg_perm.uid;
370 out->gid = tbuf_old.msg_perm.gid;
371 out->mode = tbuf_old.msg_perm.mode;
372
Ingo Molnar5a06a362006-07-30 03:04:11 -0700373 if (tbuf_old.msg_qbytes == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 out->qbytes = tbuf_old.msg_lqbytes;
375 else
376 out->qbytes = tbuf_old.msg_qbytes;
377
378 return 0;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700379 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 default:
381 return -EINVAL;
382 }
383}
384
Ingo Molnar5a06a362006-07-30 03:04:11 -0700385asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 struct kern_ipc_perm *ipcp;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700388 struct msq_setbuf setbuf;
389 struct msg_queue *msq;
390 int err, version;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700391 struct ipc_namespace *ns;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700392
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 if (msqid < 0 || cmd < 0)
394 return -EINVAL;
395
396 version = ipc_parse_version(&cmd);
Kirill Korotaev1e786932006-10-02 02:18:21 -0700397 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398
399 switch (cmd) {
Ingo Molnar5a06a362006-07-30 03:04:11 -0700400 case IPC_INFO:
401 case MSG_INFO:
402 {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 struct msginfo msginfo;
404 int max_id;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700405
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 if (!buf)
407 return -EFAULT;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700408 /*
409 * We must not return kernel stack data.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 * due to padding, it's not enough
411 * to set all member fields.
412 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 err = security_msg_queue_msgctl(NULL, cmd);
414 if (err)
415 return err;
416
Ingo Molnar5a06a362006-07-30 03:04:11 -0700417 memset(&msginfo, 0, sizeof(msginfo));
Kirill Korotaev1e786932006-10-02 02:18:21 -0700418 msginfo.msgmni = ns->msg_ctlmni;
419 msginfo.msgmax = ns->msg_ctlmax;
420 msginfo.msgmnb = ns->msg_ctlmnb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 msginfo.msgssz = MSGSSZ;
422 msginfo.msgseg = MSGSEG;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700423 mutex_lock(&msg_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 if (cmd == MSG_INFO) {
Kirill Korotaev1e786932006-10-02 02:18:21 -0700425 msginfo.msgpool = msg_ids(ns).in_use;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 msginfo.msgmap = atomic_read(&msg_hdrs);
427 msginfo.msgtql = atomic_read(&msg_bytes);
428 } else {
429 msginfo.msgmap = MSGMAP;
430 msginfo.msgpool = MSGPOOL;
431 msginfo.msgtql = MSGTQL;
432 }
Kirill Korotaev1e786932006-10-02 02:18:21 -0700433 max_id = msg_ids(ns).max_id;
434 mutex_unlock(&msg_ids(ns).mutex);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700435 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 return -EFAULT;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700437 return (max_id < 0) ? 0 : max_id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 }
439 case MSG_STAT:
440 case IPC_STAT:
441 {
442 struct msqid64_ds tbuf;
443 int success_return;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700444
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 if (!buf)
446 return -EFAULT;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700447 if (cmd == MSG_STAT && msqid >= msg_ids(ns).entries->size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 return -EINVAL;
449
Ingo Molnar5a06a362006-07-30 03:04:11 -0700450 memset(&tbuf, 0, sizeof(tbuf));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451
Kirill Korotaev1e786932006-10-02 02:18:21 -0700452 msq = msg_lock(ns, msqid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453 if (msq == NULL)
454 return -EINVAL;
455
Ingo Molnar5a06a362006-07-30 03:04:11 -0700456 if (cmd == MSG_STAT) {
Kirill Korotaev1e786932006-10-02 02:18:21 -0700457 success_return = msg_buildid(ns, msqid, msq->q_perm.seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458 } else {
459 err = -EIDRM;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700460 if (msg_checkid(ns, msq, msqid))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 goto out_unlock;
462 success_return = 0;
463 }
464 err = -EACCES;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700465 if (ipcperms(&msq->q_perm, S_IRUGO))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 goto out_unlock;
467
468 err = security_msg_queue_msgctl(msq, cmd);
469 if (err)
470 goto out_unlock;
471
472 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
473 tbuf.msg_stime = msq->q_stime;
474 tbuf.msg_rtime = msq->q_rtime;
475 tbuf.msg_ctime = msq->q_ctime;
476 tbuf.msg_cbytes = msq->q_cbytes;
477 tbuf.msg_qnum = msq->q_qnum;
478 tbuf.msg_qbytes = msq->q_qbytes;
479 tbuf.msg_lspid = msq->q_lspid;
480 tbuf.msg_lrpid = msq->q_lrpid;
481 msg_unlock(msq);
482 if (copy_msqid_to_user(buf, &tbuf, version))
483 return -EFAULT;
484 return success_return;
485 }
486 case IPC_SET:
487 if (!buf)
488 return -EFAULT;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700489 if (copy_msqid_from_user(&setbuf, buf, version))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 break;
492 case IPC_RMID:
493 break;
494 default:
495 return -EINVAL;
496 }
497
Kirill Korotaev1e786932006-10-02 02:18:21 -0700498 mutex_lock(&msg_ids(ns).mutex);
499 msq = msg_lock(ns, msqid);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700500 err = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 if (msq == NULL)
502 goto out_up;
503
504 err = -EIDRM;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700505 if (msg_checkid(ns, msq, msqid))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506 goto out_unlock_up;
507 ipcp = &msq->q_perm;
Steve Grubb073115d2006-04-02 17:07:33 -0400508
509 err = audit_ipc_obj(ipcp);
510 if (err)
511 goto out_unlock_up;
Linda Knippersac032212006-05-16 22:03:48 -0400512 if (cmd==IPC_SET) {
Ingo Molnar5a06a362006-07-30 03:04:11 -0700513 err = audit_ipc_set_perm(setbuf.qbytes, setbuf.uid, setbuf.gid,
514 setbuf.mode);
Linda Knippersac032212006-05-16 22:03:48 -0400515 if (err)
516 goto out_unlock_up;
517 }
Steve Grubb073115d2006-04-02 17:07:33 -0400518
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 err = -EPERM;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700520 if (current->euid != ipcp->cuid &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN))
Ingo Molnar5a06a362006-07-30 03:04:11 -0700522 /* We _could_ check for CAP_CHOWN above, but we don't */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 goto out_unlock_up;
524
525 err = security_msg_queue_msgctl(msq, cmd);
526 if (err)
527 goto out_unlock_up;
528
529 switch (cmd) {
530 case IPC_SET:
531 {
532 err = -EPERM;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700533 if (setbuf.qbytes > ns->msg_ctlmnb && !capable(CAP_SYS_RESOURCE))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 goto out_unlock_up;
535
536 msq->q_qbytes = setbuf.qbytes;
537
538 ipcp->uid = setbuf.uid;
539 ipcp->gid = setbuf.gid;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700540 ipcp->mode = (ipcp->mode & ~S_IRWXUGO) |
541 (S_IRWXUGO & setbuf.mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 msq->q_ctime = get_seconds();
543 /* sleeping receivers might be excluded by
544 * stricter permissions.
545 */
Ingo Molnar5a06a362006-07-30 03:04:11 -0700546 expunge_all(msq, -EAGAIN);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 /* sleeping senders might be able to send
548 * due to a larger queue size.
549 */
Ingo Molnar5a06a362006-07-30 03:04:11 -0700550 ss_wakeup(&msq->q_senders, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 msg_unlock(msq);
552 break;
553 }
554 case IPC_RMID:
Kirill Korotaev1e786932006-10-02 02:18:21 -0700555 freeque(ns, msq, msqid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 break;
557 }
558 err = 0;
559out_up:
Kirill Korotaev1e786932006-10-02 02:18:21 -0700560 mutex_unlock(&msg_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 return err;
562out_unlock_up:
563 msg_unlock(msq);
564 goto out_up;
565out_unlock:
566 msg_unlock(msq);
567 return err;
568}
569
Ingo Molnar5a06a362006-07-30 03:04:11 -0700570static int testmsg(struct msg_msg *msg, long type, int mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571{
572 switch(mode)
573 {
574 case SEARCH_ANY:
575 return 1;
576 case SEARCH_LESSEQUAL:
Ingo Molnar5a06a362006-07-30 03:04:11 -0700577 if (msg->m_type <=type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 return 1;
579 break;
580 case SEARCH_EQUAL:
Ingo Molnar5a06a362006-07-30 03:04:11 -0700581 if (msg->m_type == type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 return 1;
583 break;
584 case SEARCH_NOTEQUAL:
Ingo Molnar5a06a362006-07-30 03:04:11 -0700585 if (msg->m_type != type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 return 1;
587 break;
588 }
589 return 0;
590}
591
Ingo Molnar5a06a362006-07-30 03:04:11 -0700592static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593{
Ingo Molnar5a06a362006-07-30 03:04:11 -0700594 struct list_head *tmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595
596 tmp = msq->q_receivers.next;
597 while (tmp != &msq->q_receivers) {
Ingo Molnar5a06a362006-07-30 03:04:11 -0700598 struct msg_receiver *msr;
599
600 msr = list_entry(tmp, struct msg_receiver, r_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 tmp = tmp->next;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700602 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
603 !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
604 msr->r_msgtype, msr->r_mode)) {
605
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 list_del(&msr->r_list);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700607 if (msr->r_maxsize < msg->m_ts) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 msr->r_msg = NULL;
609 wake_up_process(msr->r_tsk);
610 smp_mb();
611 msr->r_msg = ERR_PTR(-E2BIG);
612 } else {
613 msr->r_msg = NULL;
614 msq->q_lrpid = msr->r_tsk->pid;
615 msq->q_rtime = get_seconds();
616 wake_up_process(msr->r_tsk);
617 smp_mb();
618 msr->r_msg = msg;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700619
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 return 1;
621 }
622 }
623 }
624 return 0;
625}
626
suzuki651971c2006-12-06 20:37:48 -0800627long do_msgsnd(int msqid, long mtype, void __user *mtext,
628 size_t msgsz, int msgflg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629{
630 struct msg_queue *msq;
631 struct msg_msg *msg;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 int err;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700633 struct ipc_namespace *ns;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700634
Kirill Korotaev1e786932006-10-02 02:18:21 -0700635 ns = current->nsproxy->ipc_ns;
636
637 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 if (mtype < 1)
640 return -EINVAL;
641
suzuki651971c2006-12-06 20:37:48 -0800642 msg = load_msg(mtext, msgsz);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700643 if (IS_ERR(msg))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 return PTR_ERR(msg);
645
646 msg->m_type = mtype;
647 msg->m_ts = msgsz;
648
Kirill Korotaev1e786932006-10-02 02:18:21 -0700649 msq = msg_lock(ns, msqid);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700650 err = -EINVAL;
651 if (msq == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 goto out_free;
653
654 err= -EIDRM;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700655 if (msg_checkid(ns, msq, msqid))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 goto out_unlock_free;
657
658 for (;;) {
659 struct msg_sender s;
660
Ingo Molnar5a06a362006-07-30 03:04:11 -0700661 err = -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 if (ipcperms(&msq->q_perm, S_IWUGO))
663 goto out_unlock_free;
664
665 err = security_msg_queue_msgsnd(msq, msg, msgflg);
666 if (err)
667 goto out_unlock_free;
668
Ingo Molnar5a06a362006-07-30 03:04:11 -0700669 if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 1 + msq->q_qnum <= msq->q_qbytes) {
671 break;
672 }
673
674 /* queue full, wait: */
Ingo Molnar5a06a362006-07-30 03:04:11 -0700675 if (msgflg & IPC_NOWAIT) {
676 err = -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 goto out_unlock_free;
678 }
679 ss_add(msq, &s);
680 ipc_rcu_getref(msq);
681 msg_unlock(msq);
682 schedule();
683
684 ipc_lock_by_ptr(&msq->q_perm);
685 ipc_rcu_putref(msq);
686 if (msq->q_perm.deleted) {
687 err = -EIDRM;
688 goto out_unlock_free;
689 }
690 ss_del(&s);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700691
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 if (signal_pending(current)) {
Ingo Molnar5a06a362006-07-30 03:04:11 -0700693 err = -ERESTARTNOHAND;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 goto out_unlock_free;
695 }
696 }
697
698 msq->q_lspid = current->tgid;
699 msq->q_stime = get_seconds();
700
Ingo Molnar5a06a362006-07-30 03:04:11 -0700701 if (!pipelined_send(msq, msg)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 /* noone is waiting for this message, enqueue it */
Ingo Molnar5a06a362006-07-30 03:04:11 -0700703 list_add_tail(&msg->m_list, &msq->q_messages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704 msq->q_cbytes += msgsz;
705 msq->q_qnum++;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700706 atomic_add(msgsz, &msg_bytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707 atomic_inc(&msg_hdrs);
708 }
Ingo Molnar5a06a362006-07-30 03:04:11 -0700709
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 err = 0;
711 msg = NULL;
712
713out_unlock_free:
714 msg_unlock(msq);
715out_free:
Ingo Molnar5a06a362006-07-30 03:04:11 -0700716 if (msg != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717 free_msg(msg);
718 return err;
719}
720
suzuki651971c2006-12-06 20:37:48 -0800721asmlinkage long
722sys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz, int msgflg)
723{
724 long mtype;
725
726 if (get_user(mtype, &msgp->mtype))
727 return -EFAULT;
728 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
729}
730
Ingo Molnar5a06a362006-07-30 03:04:11 -0700731static inline int convert_mode(long *msgtyp, int msgflg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732{
Ingo Molnar5a06a362006-07-30 03:04:11 -0700733 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 * find message of correct type.
735 * msgtyp = 0 => get first.
736 * msgtyp > 0 => get first message of matching type.
Ingo Molnar5a06a362006-07-30 03:04:11 -0700737 * msgtyp < 0 => get message with least type must be < abs(msgtype).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 */
Ingo Molnar5a06a362006-07-30 03:04:11 -0700739 if (*msgtyp == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 return SEARCH_ANY;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700741 if (*msgtyp < 0) {
742 *msgtyp = -*msgtyp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 return SEARCH_LESSEQUAL;
744 }
Ingo Molnar5a06a362006-07-30 03:04:11 -0700745 if (msgflg & MSG_EXCEPT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 return SEARCH_NOTEQUAL;
747 return SEARCH_EQUAL;
748}
749
suzuki651971c2006-12-06 20:37:48 -0800750long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
751 size_t msgsz, long msgtyp, int msgflg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752{
753 struct msg_queue *msq;
754 struct msg_msg *msg;
755 int mode;
Kirill Korotaev1e786932006-10-02 02:18:21 -0700756 struct ipc_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757
758 if (msqid < 0 || (long) msgsz < 0)
759 return -EINVAL;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700760 mode = convert_mode(&msgtyp, msgflg);
Kirill Korotaev1e786932006-10-02 02:18:21 -0700761 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762
Kirill Korotaev1e786932006-10-02 02:18:21 -0700763 msq = msg_lock(ns, msqid);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700764 if (msq == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 return -EINVAL;
766
767 msg = ERR_PTR(-EIDRM);
Kirill Korotaev1e786932006-10-02 02:18:21 -0700768 if (msg_checkid(ns, msq, msqid))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 goto out_unlock;
770
771 for (;;) {
772 struct msg_receiver msr_d;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700773 struct list_head *tmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774
775 msg = ERR_PTR(-EACCES);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700776 if (ipcperms(&msq->q_perm, S_IRUGO))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 goto out_unlock;
778
779 msg = ERR_PTR(-EAGAIN);
780 tmp = msq->q_messages.next;
781 while (tmp != &msq->q_messages) {
782 struct msg_msg *walk_msg;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700783
784 walk_msg = list_entry(tmp, struct msg_msg, m_list);
785 if (testmsg(walk_msg, msgtyp, mode) &&
786 !security_msg_queue_msgrcv(msq, walk_msg, current,
787 msgtyp, mode)) {
788
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 msg = walk_msg;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700790 if (mode == SEARCH_LESSEQUAL &&
791 walk_msg->m_type != 1) {
792 msg = walk_msg;
793 msgtyp = walk_msg->m_type - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 } else {
Ingo Molnar5a06a362006-07-30 03:04:11 -0700795 msg = walk_msg;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 break;
797 }
798 }
799 tmp = tmp->next;
800 }
Ingo Molnar5a06a362006-07-30 03:04:11 -0700801 if (!IS_ERR(msg)) {
802 /*
803 * Found a suitable message.
804 * Unlink it from the queue.
805 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
807 msg = ERR_PTR(-E2BIG);
808 goto out_unlock;
809 }
810 list_del(&msg->m_list);
811 msq->q_qnum--;
812 msq->q_rtime = get_seconds();
813 msq->q_lrpid = current->tgid;
814 msq->q_cbytes -= msg->m_ts;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700815 atomic_sub(msg->m_ts, &msg_bytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 atomic_dec(&msg_hdrs);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700817 ss_wakeup(&msq->q_senders, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 msg_unlock(msq);
819 break;
820 }
821 /* No message waiting. Wait for a message */
822 if (msgflg & IPC_NOWAIT) {
823 msg = ERR_PTR(-ENOMSG);
824 goto out_unlock;
825 }
Ingo Molnar5a06a362006-07-30 03:04:11 -0700826 list_add_tail(&msr_d.r_list, &msq->q_receivers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 msr_d.r_tsk = current;
828 msr_d.r_msgtype = msgtyp;
829 msr_d.r_mode = mode;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700830 if (msgflg & MSG_NOERROR)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 msr_d.r_maxsize = INT_MAX;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700832 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 msr_d.r_maxsize = msgsz;
834 msr_d.r_msg = ERR_PTR(-EAGAIN);
835 current->state = TASK_INTERRUPTIBLE;
836 msg_unlock(msq);
837
838 schedule();
839
840 /* Lockless receive, part 1:
841 * Disable preemption. We don't hold a reference to the queue
842 * and getting a reference would defeat the idea of a lockless
843 * operation, thus the code relies on rcu to guarantee the
844 * existance of msq:
845 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
846 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
847 * rcu_read_lock() prevents preemption between reading r_msg
848 * and the spin_lock() inside ipc_lock_by_ptr().
849 */
850 rcu_read_lock();
851
852 /* Lockless receive, part 2:
853 * Wait until pipelined_send or expunge_all are outside of
854 * wake_up_process(). There is a race with exit(), see
855 * ipc/mqueue.c for the details.
856 */
Ingo Molnar5a06a362006-07-30 03:04:11 -0700857 msg = (struct msg_msg*)msr_d.r_msg;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858 while (msg == NULL) {
859 cpu_relax();
Ingo Molnar5a06a362006-07-30 03:04:11 -0700860 msg = (struct msg_msg *)msr_d.r_msg;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861 }
862
863 /* Lockless receive, part 3:
864 * If there is a message or an error then accept it without
865 * locking.
866 */
Ingo Molnar5a06a362006-07-30 03:04:11 -0700867 if (msg != ERR_PTR(-EAGAIN)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 rcu_read_unlock();
869 break;
870 }
871
872 /* Lockless receive, part 3:
873 * Acquire the queue spinlock.
874 */
875 ipc_lock_by_ptr(&msq->q_perm);
876 rcu_read_unlock();
877
878 /* Lockless receive, part 4:
879 * Repeat test after acquiring the spinlock.
880 */
881 msg = (struct msg_msg*)msr_d.r_msg;
Ingo Molnar5a06a362006-07-30 03:04:11 -0700882 if (msg != ERR_PTR(-EAGAIN))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883 goto out_unlock;
884
885 list_del(&msr_d.r_list);
886 if (signal_pending(current)) {
887 msg = ERR_PTR(-ERESTARTNOHAND);
888out_unlock:
889 msg_unlock(msq);
890 break;
891 }
892 }
893 if (IS_ERR(msg))
Ingo Molnar5a06a362006-07-30 03:04:11 -0700894 return PTR_ERR(msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895
896 msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz;
suzuki651971c2006-12-06 20:37:48 -0800897 *pmtype = msg->m_type;
898 if (store_msg(mtext, msg, msgsz))
Ingo Molnar5a06a362006-07-30 03:04:11 -0700899 msgsz = -EFAULT;
suzuki651971c2006-12-06 20:37:48 -0800900
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 free_msg(msg);
Ingo Molnar5a06a362006-07-30 03:04:11 -0700902
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 return msgsz;
904}
905
suzuki651971c2006-12-06 20:37:48 -0800906asmlinkage long sys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
907 long msgtyp, int msgflg)
908{
909 long err, mtype;
910
911 err = do_msgrcv(msqid, &mtype, msgp->mtext, msgsz, msgtyp, msgflg);
912 if (err < 0)
913 goto out;
914
915 if (put_user(mtype, &msgp->mtype))
916 err = -EFAULT;
917out:
918 return err;
919}
920
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -0700922static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923{
Mike Waychison19b49462005-09-06 15:17:10 -0700924 struct msg_queue *msq = it;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925
Mike Waychison19b49462005-09-06 15:17:10 -0700926 return seq_printf(s,
Ingo Molnar5a06a362006-07-30 03:04:11 -0700927 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
928 msq->q_perm.key,
929 msq->q_id,
930 msq->q_perm.mode,
931 msq->q_cbytes,
932 msq->q_qnum,
933 msq->q_lspid,
934 msq->q_lrpid,
935 msq->q_perm.uid,
936 msq->q_perm.gid,
937 msq->q_perm.cuid,
938 msq->q_perm.cgid,
939 msq->q_stime,
940 msq->q_rtime,
941 msq->q_ctime);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942}
943#endif