msgutil.c revision 435d5f4b
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};
36
37atomic_t nr_ipc_ns = ATOMIC_INIT(1);
38
39struct msg_msgseg {
40	struct msg_msgseg *next;
41	/* the next part of the message follows immediately */
42};
43
44#define DATALEN_MSG	((size_t)PAGE_SIZE-sizeof(struct msg_msg))
45#define DATALEN_SEG	((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
46
47
48static struct msg_msg *alloc_msg(size_t len)
49{
50	struct msg_msg *msg;
51	struct msg_msgseg **pseg;
52	size_t alen;
53
54	alen = min(len, DATALEN_MSG);
55	msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
56	if (msg == NULL)
57		return NULL;
58
59	msg->next = NULL;
60	msg->security = NULL;
61
62	len -= alen;
63	pseg = &msg->next;
64	while (len > 0) {
65		struct msg_msgseg *seg;
66		alen = min(len, DATALEN_SEG);
67		seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL);
68		if (seg == NULL)
69			goto out_err;
70		*pseg = seg;
71		seg->next = NULL;
72		pseg = &seg->next;
73		len -= alen;
74	}
75
76	return msg;
77
78out_err:
79	free_msg(msg);
80	return NULL;
81}
82
83struct msg_msg *load_msg(const void __user *src, size_t len)
84{
85	struct msg_msg *msg;
86	struct msg_msgseg *seg;
87	int err = -EFAULT;
88	size_t alen;
89
90	msg = alloc_msg(len);
91	if (msg == NULL)
92		return ERR_PTR(-ENOMEM);
93
94	alen = min(len, DATALEN_MSG);
95	if (copy_from_user(msg + 1, src, alen))
96		goto out_err;
97
98	for (seg = msg->next; seg != NULL; seg = seg->next) {
99		len -= alen;
100		src = (char __user *)src + alen;
101		alen = min(len, DATALEN_SEG);
102		if (copy_from_user(seg + 1, src, alen))
103			goto out_err;
104	}
105
106	err = security_msg_msg_alloc(msg);
107	if (err)
108		goto out_err;
109
110	return msg;
111
112out_err:
113	free_msg(msg);
114	return ERR_PTR(err);
115}
116#ifdef CONFIG_CHECKPOINT_RESTORE
117struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
118{
119	struct msg_msgseg *dst_pseg, *src_pseg;
120	size_t len = src->m_ts;
121	size_t alen;
122
123	BUG_ON(dst == NULL);
124	if (src->m_ts > dst->m_ts)
125		return ERR_PTR(-EINVAL);
126
127	alen = min(len, DATALEN_MSG);
128	memcpy(dst + 1, src + 1, alen);
129
130	for (dst_pseg = dst->next, src_pseg = src->next;
131	     src_pseg != NULL;
132	     dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
133
134		len -= alen;
135		alen = min(len, DATALEN_SEG);
136		memcpy(dst_pseg + 1, src_pseg + 1, alen);
137	}
138
139	dst->m_type = src->m_type;
140	dst->m_ts = src->m_ts;
141
142	return dst;
143}
144#else
145struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
146{
147	return ERR_PTR(-ENOSYS);
148}
149#endif
150int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
151{
152	size_t alen;
153	struct msg_msgseg *seg;
154
155	alen = min(len, DATALEN_MSG);
156	if (copy_to_user(dest, msg + 1, alen))
157		return -1;
158
159	for (seg = msg->next; seg != NULL; seg = seg->next) {
160		len -= alen;
161		dest = (char __user *)dest + alen;
162		alen = min(len, DATALEN_SEG);
163		if (copy_to_user(dest, seg + 1, alen))
164			return -1;
165	}
166	return 0;
167}
168
169void free_msg(struct msg_msg *msg)
170{
171	struct msg_msgseg *seg;
172
173	security_msg_msg_free(msg);
174
175	seg = msg->next;
176	kfree(msg);
177	while (seg != NULL) {
178		struct msg_msgseg *tmp = seg->next;
179		kfree(seg);
180		seg = tmp;
181	}
182}
183