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_fs.h>
20#include <asm/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 (PAGE_SIZE-sizeof(struct msg_msg))
45#define DATALEN_SEG (PAGE_SIZE-sizeof(struct msg_msgseg))
46
47struct msg_msg *load_msg(const void __user *src, int len)
48{
49    struct msg_msg *msg;
50    struct msg_msgseg **pseg;
51    int err;
52    int alen;
53
54    alen = len;
55    if (alen > DATALEN_MSG)
56        alen = DATALEN_MSG;
57
58    msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
59    if (msg == NULL)
60        return ERR_PTR(-ENOMEM);
61
62    msg->next = NULL;
63    msg->security = NULL;
64
65    if (copy_from_user(msg + 1, src, alen)) {
66        err = -EFAULT;
67        goto out_err;
68    }
69
70    len -= alen;
71    src = ((char __user *)src) + alen;
72    pseg = &msg->next;
73    while (len > 0) {
74        struct msg_msgseg *seg;
75        alen = len;
76        if (alen > DATALEN_SEG)
77            alen = DATALEN_SEG;
78        seg = kmalloc(sizeof(*seg) + alen,
79                         GFP_KERNEL);
80        if (seg == NULL) {
81            err = -ENOMEM;
82            goto out_err;
83        }
84        *pseg = seg;
85        seg->next = NULL;
86        if (copy_from_user(seg + 1, src, alen)) {
87            err = -EFAULT;
88            goto out_err;
89        }
90        pseg = &seg->next;
91        len -= alen;
92        src = ((char __user *)src) + alen;
93    }
94
95    err = security_msg_msg_alloc(msg);
96    if (err)
97        goto out_err;
98
99    return msg;
100
101out_err:
102    free_msg(msg);
103    return ERR_PTR(err);
104}
105#ifdef CONFIG_CHECKPOINT_RESTORE
106struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
107{
108    struct msg_msgseg *dst_pseg, *src_pseg;
109    int len = src->m_ts;
110    int alen;
111
112    BUG_ON(dst == NULL);
113    if (src->m_ts > dst->m_ts)
114        return ERR_PTR(-EINVAL);
115
116    alen = len;
117    if (alen > DATALEN_MSG)
118        alen = DATALEN_MSG;
119
120    memcpy(dst + 1, src + 1, alen);
121
122    len -= alen;
123    dst_pseg = dst->next;
124    src_pseg = src->next;
125    while (len > 0) {
126        alen = len;
127        if (alen > DATALEN_SEG)
128            alen = DATALEN_SEG;
129        memcpy(dst_pseg + 1, src_pseg + 1, alen);
130        dst_pseg = dst_pseg->next;
131        len -= alen;
132        src_pseg = src_pseg->next;
133    }
134
135    dst->m_type = src->m_type;
136    dst->m_ts = src->m_ts;
137
138    return dst;
139}
140#else
141struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
142{
143    return ERR_PTR(-ENOSYS);
144}
145#endif
146int store_msg(void __user *dest, struct msg_msg *msg, int len)
147{
148    int alen;
149    struct msg_msgseg *seg;
150
151    alen = len;
152    if (alen > DATALEN_MSG)
153        alen = DATALEN_MSG;
154    if (copy_to_user(dest, msg + 1, alen))
155        return -1;
156
157    len -= alen;
158    dest = ((char __user *)dest) + alen;
159    seg = msg->next;
160    while (len > 0) {
161        alen = len;
162        if (alen > DATALEN_SEG)
163            alen = DATALEN_SEG;
164        if (copy_to_user(dest, seg + 1, alen))
165            return -1;
166        len -= alen;
167        dest = ((char __user *)dest) + alen;
168        seg = seg->next;
169    }
170    return 0;
171}
172
173void free_msg(struct msg_msg *msg)
174{
175    struct msg_msgseg *seg;
176
177    security_msg_msg_free(msg);
178
179    seg = msg->next;
180    kfree(msg);
181    while (seg != NULL) {
182        struct msg_msgseg *tmp = seg->next;
183        kfree(seg);
184        seg = tmp;
185    }
186}
187

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