Root/ipc/msgutil.c

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    .proc_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

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