1/*
2 * linux/ipc/msgutil.c
3 * Copyright (C) 1999, 2004 Manfred Spraul
4 *
5 * This file is released under GNU General Public Licence version 2 or
6 * (at your option) any later version.
7 *
8 * See the file COPYING for more details.
9 */
10
11#include <linux/spinlock.h>
12#include <linux/init.h>
13#include <linux/security.h>
14#include <linux/slab.h>
15#include <linux/ipc.h>
16#include <linux/msg.h>
17#include <linux/ipc_namespace.h>
18#include <linux/utsname.h>
19#include <linux/proc_ns.h>
20#include <linux/uaccess.h>
21
22#include "util.h"
23
24DEFINE_SPINLOCK(mq_lock);
25
26/*
27 * The next 2 defines are here bc this is the only file
28 * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
29 * and not CONFIG_IPC_NS.
30 */
31struct ipc_namespace init_ipc_ns = {
32	.count		= ATOMIC_INIT(1),
33	.user_ns = &init_user_ns,
34	.ns.inum = PROC_IPC_INIT_INO,
35#ifdef CONFIG_IPC_NS
36	.ns.ops = &ipcns_operations,
37#endif
38};
39
40atomic_t nr_ipc_ns = ATOMIC_INIT(1);
41
42struct msg_msgseg {
43	struct msg_msgseg *next;
44	/* the next part of the message follows immediately */
45};
46
47#define DATALEN_MSG	((size_t)PAGE_SIZE-sizeof(struct msg_msg))
48#define DATALEN_SEG	((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
49
50
51static struct msg_msg *alloc_msg(size_t len)
52{
53	struct msg_msg *msg;
54	struct msg_msgseg **pseg;
55	size_t alen;
56
57	alen = min(len, DATALEN_MSG);
58	msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
59	if (msg == NULL)
60		return NULL;
61
62	msg->next = NULL;
63	msg->security = NULL;
64
65	len -= alen;
66	pseg = &msg->next;
67	while (len > 0) {
68		struct msg_msgseg *seg;
69		alen = min(len, DATALEN_SEG);
70		seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL);
71		if (seg == NULL)
72			goto out_err;
73		*pseg = seg;
74		seg->next = NULL;
75		pseg = &seg->next;
76		len -= alen;
77	}
78
79	return msg;
80
81out_err:
82	free_msg(msg);
83	return NULL;
84}
85
86struct msg_msg *load_msg(const void __user *src, size_t len)
87{
88	struct msg_msg *msg;
89	struct msg_msgseg *seg;
90	int err = -EFAULT;
91	size_t alen;
92
93	msg = alloc_msg(len);
94	if (msg == NULL)
95		return ERR_PTR(-ENOMEM);
96
97	alen = min(len, DATALEN_MSG);
98	if (copy_from_user(msg + 1, src, alen))
99		goto out_err;
100
101	for (seg = msg->next; seg != NULL; seg = seg->next) {
102		len -= alen;
103		src = (char __user *)src + alen;
104		alen = min(len, DATALEN_SEG);
105		if (copy_from_user(seg + 1, src, alen))
106			goto out_err;
107	}
108
109	err = security_msg_msg_alloc(msg);
110	if (err)
111		goto out_err;
112
113	return msg;
114
115out_err:
116	free_msg(msg);
117	return ERR_PTR(err);
118}
119#ifdef CONFIG_CHECKPOINT_RESTORE
120struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
121{
122	struct msg_msgseg *dst_pseg, *src_pseg;
123	size_t len = src->m_ts;
124	size_t alen;
125
126	WARN_ON(dst == NULL);
127	if (src->m_ts > dst->m_ts)
128		return ERR_PTR(-EINVAL);
129
130	alen = min(len, DATALEN_MSG);
131	memcpy(dst + 1, src + 1, alen);
132
133	for (dst_pseg = dst->next, src_pseg = src->next;
134	     src_pseg != NULL;
135	     dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
136
137		len -= alen;
138		alen = min(len, DATALEN_SEG);
139		memcpy(dst_pseg + 1, src_pseg + 1, alen);
140	}
141
142	dst->m_type = src->m_type;
143	dst->m_ts = src->m_ts;
144
145	return dst;
146}
147#else
148struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
149{
150	return ERR_PTR(-ENOSYS);
151}
152#endif
153int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
154{
155	size_t alen;
156	struct msg_msgseg *seg;
157
158	alen = min(len, DATALEN_MSG);
159	if (copy_to_user(dest, msg + 1, alen))
160		return -1;
161
162	for (seg = msg->next; seg != NULL; seg = seg->next) {
163		len -= alen;
164		dest = (char __user *)dest + alen;
165		alen = min(len, DATALEN_SEG);
166		if (copy_to_user(dest, seg + 1, alen))
167			return -1;
168	}
169	return 0;
170}
171
172void free_msg(struct msg_msg *msg)
173{
174	struct msg_msgseg *seg;
175
176	security_msg_msg_free(msg);
177
178	seg = msg->next;
179	kfree(msg);
180	while (seg != NULL) {
181		struct msg_msgseg *tmp = seg->next;
182		kfree(seg);
183		seg = tmp;
184	}
185}
186