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#include <linux/nstree.h>
19
20#include "util.h"
21
22DEFINE_SPINLOCK(mq_lock);
23
24/*
25 * The next 2 defines are here bc this is the only file
26 * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
27 * and not CONFIG_IPC_NS.
28 */
29struct ipc_namespace init_ipc_ns = {
30 .ns = NS_COMMON_INIT(init_ipc_ns),
31 .user_ns = &init_user_ns,
32};
33
34struct msg_msgseg {
35 struct msg_msgseg *next;
36 /* the next part of the message follows immediately */
37};
38
39#define DATALEN_MSG ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
40#define DATALEN_SEG ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
41
42static kmem_buckets *msg_buckets __ro_after_init;
43
44static int __init init_msg_buckets(void)
45{
46 msg_buckets = kmem_buckets_create(name: "msg_msg", SLAB_ACCOUNT,
47 useroffset: sizeof(struct msg_msg),
48 DATALEN_MSG, NULL);
49
50 return 0;
51}
52subsys_initcall(init_msg_buckets);
53
54static struct msg_msg *alloc_msg(size_t len)
55{
56 struct msg_msg *msg;
57 struct msg_msgseg **pseg;
58 size_t alen;
59
60 alen = min(len, DATALEN_MSG);
61 msg = kmem_buckets_alloc(msg_buckets, sizeof(*msg) + alen, GFP_KERNEL);
62 if (msg == NULL)
63 return NULL;
64
65 msg->next = NULL;
66 msg->security = NULL;
67
68 len -= alen;
69 pseg = &msg->next;
70 while (len > 0) {
71 struct msg_msgseg *seg;
72
73 cond_resched();
74
75 alen = min(len, DATALEN_SEG);
76 seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT);
77 if (seg == NULL)
78 goto out_err;
79 *pseg = seg;
80 seg->next = NULL;
81 pseg = &seg->next;
82 len -= alen;
83 }
84
85 return msg;
86
87out_err:
88 free_msg(msg);
89 return NULL;
90}
91
92struct msg_msg *load_msg(const void __user *src, size_t len)
93{
94 struct msg_msg *msg;
95 struct msg_msgseg *seg;
96 int err = -EFAULT;
97 size_t alen;
98
99 msg = alloc_msg(len);
100 if (msg == NULL)
101 return ERR_PTR(error: -ENOMEM);
102
103 alen = min(len, DATALEN_MSG);
104 if (copy_from_user(to: msg + 1, from: src, n: alen))
105 goto out_err;
106
107 for (seg = msg->next; seg != NULL; seg = seg->next) {
108 len -= alen;
109 src = (char __user *)src + alen;
110 alen = min(len, DATALEN_SEG);
111 if (copy_from_user(to: seg + 1, from: src, n: alen))
112 goto out_err;
113 }
114
115 err = security_msg_msg_alloc(msg);
116 if (err)
117 goto out_err;
118
119 return msg;
120
121out_err:
122 free_msg(msg);
123 return ERR_PTR(error: err);
124}
125#ifdef CONFIG_CHECKPOINT_RESTORE
126struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
127{
128 struct msg_msgseg *dst_pseg, *src_pseg;
129 size_t len = src->m_ts;
130 size_t alen;
131
132 if (src->m_ts > dst->m_ts)
133 return ERR_PTR(error: -EINVAL);
134
135 alen = min(len, DATALEN_MSG);
136 memcpy(dst + 1, src + 1, alen);
137
138 for (dst_pseg = dst->next, src_pseg = src->next;
139 src_pseg != NULL;
140 dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
141
142 len -= alen;
143 alen = min(len, DATALEN_SEG);
144 memcpy(dst_pseg + 1, src_pseg + 1, alen);
145 }
146
147 dst->m_type = src->m_type;
148 dst->m_ts = src->m_ts;
149
150 return dst;
151}
152#else
153struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
154{
155 return ERR_PTR(-ENOSYS);
156}
157#endif
158int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
159{
160 size_t alen;
161 struct msg_msgseg *seg;
162
163 alen = min(len, DATALEN_MSG);
164 if (copy_to_user(to: dest, from: msg + 1, n: alen))
165 return -1;
166
167 for (seg = msg->next; seg != NULL; seg = seg->next) {
168 len -= alen;
169 dest = (char __user *)dest + alen;
170 alen = min(len, DATALEN_SEG);
171 if (copy_to_user(to: dest, from: seg + 1, n: alen))
172 return -1;
173 }
174 return 0;
175}
176
177void free_msg(struct msg_msg *msg)
178{
179 struct msg_msgseg *seg;
180
181 security_msg_msg_free(msg);
182
183 seg = msg->next;
184 kfree(objp: msg);
185 while (seg != NULL) {
186 struct msg_msgseg *tmp = seg->next;
187
188 cond_resched();
189 kfree(objp: seg);
190 seg = tmp;
191 }
192}
193

source code of linux/ipc/msgutil.c