msgutil.c revision 137ec390
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * linux/ipc/msgutil.c
4 * Copyright (C) 1999, 2004 Manfred Spraul
5 */
6
7#include <linux/spinlock.h>
8#include <linux/init.h>
9#include <linux/security.h>
10#include <linux/slab.h>
11#include <linux/ipc.h>
12#include <linux/msg.h>
13#include <linux/ipc_namespace.h>
14#include <linux/utsname.h>
15#include <linux/proc_ns.h>
16#include <linux/uaccess.h>
17#include <linux/sched.h>
18
19#include "util.h"
20
21DEFINE_SPINLOCK(mq_lock);
22
23/*
24 * The next 2 defines are here bc this is the only file
25 * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
26 * and not CONFIG_IPC_NS.
27 */
28struct ipc_namespace init_ipc_ns = {
29	.ns.count = REFCOUNT_INIT(1),
30	.user_ns = &init_user_ns,
31	.ns.inum = PROC_IPC_INIT_INO,
32#ifdef CONFIG_IPC_NS
33	.ns.ops = &ipcns_operations,
34#endif
35};
36
37struct msg_msgseg {
38	struct msg_msgseg *next;
39	/* the next part of the message follows immediately */
40};
41
42#define DATALEN_MSG	((size_t)PAGE_SIZE-sizeof(struct msg_msg))
43#define DATALEN_SEG	((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
44
45
46static struct msg_msg *alloc_msg(size_t len)
47{
48	struct msg_msg *msg;
49	struct msg_msgseg **pseg;
50	size_t alen;
51
52	alen = min(len, DATALEN_MSG);
53	msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL_ACCOUNT);
54	if (msg == NULL)
55		return NULL;
56
57	msg->next = NULL;
58	msg->security = NULL;
59
60	len -= alen;
61	pseg = &msg->next;
62	while (len > 0) {
63		struct msg_msgseg *seg;
64
65		cond_resched();
66
67		alen = min(len, DATALEN_SEG);
68		seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT);
69		if (seg == NULL)
70			goto out_err;
71		*pseg = seg;
72		seg->next = NULL;
73		pseg = &seg->next;
74		len -= alen;
75	}
76
77	return msg;
78
79out_err:
80	free_msg(msg);
81	return NULL;
82}
83
84struct msg_msg *load_msg(const void __user *src, size_t len)
85{
86	struct msg_msg *msg;
87	struct msg_msgseg *seg;
88	int err = -EFAULT;
89	size_t alen;
90
91	msg = alloc_msg(len);
92	if (msg == NULL)
93		return ERR_PTR(-ENOMEM);
94
95	alen = min(len, DATALEN_MSG);
96	if (copy_from_user(msg + 1, src, alen))
97		goto out_err;
98
99	for (seg = msg->next; seg != NULL; seg = seg->next) {
100		len -= alen;
101		src = (char __user *)src + alen;
102		alen = min(len, DATALEN_SEG);
103		if (copy_from_user(seg + 1, src, alen))
104			goto out_err;
105	}
106
107	err = security_msg_msg_alloc(msg);
108	if (err)
109		goto out_err;
110
111	return msg;
112
113out_err:
114	free_msg(msg);
115	return ERR_PTR(err);
116}
117#ifdef CONFIG_CHECKPOINT_RESTORE
118struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
119{
120	struct msg_msgseg *dst_pseg, *src_pseg;
121	size_t len = src->m_ts;
122	size_t alen;
123
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
180		cond_resched();
181		kfree(seg);
182		seg = tmp;
183	}
184}
185