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/ipc_namespace.h>
17#include <asm/uaccess.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    .count = ATOMIC_INIT(1),
30#ifdef CONFIG_POSIX_MQUEUE
31    .mq_queues_max = DFLT_QUEUESMAX,
32    .mq_msg_max = DFLT_MSGMAX,
33    .mq_msgsize_max = DFLT_MSGSIZEMAX,
34#endif
35    .user_ns = &init_user_ns,
36};
37
38atomic_t nr_ipc_ns = ATOMIC_INIT(1);
39
40struct msg_msgseg {
41    struct msg_msgseg* next;
42    /* the next part of the message follows immediately */
43};
44
45#define DATALEN_MSG (PAGE_SIZE-sizeof(struct msg_msg))
46#define DATALEN_SEG (PAGE_SIZE-sizeof(struct msg_msgseg))
47
48struct msg_msg *load_msg(const void __user *src, int len)
49{
50    struct msg_msg *msg;
51    struct msg_msgseg **pseg;
52    int err;
53    int alen;
54
55    alen = len;
56    if (alen > DATALEN_MSG)
57        alen = DATALEN_MSG;
58
59    msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
60    if (msg == NULL)
61        return ERR_PTR(-ENOMEM);
62
63    msg->next = NULL;
64    msg->security = NULL;
65
66    if (copy_from_user(msg + 1, src, alen)) {
67        err = -EFAULT;
68        goto out_err;
69    }
70
71    len -= alen;
72    src = ((char __user *)src) + alen;
73    pseg = &msg->next;
74    while (len > 0) {
75        struct msg_msgseg *seg;
76        alen = len;
77        if (alen > DATALEN_SEG)
78            alen = DATALEN_SEG;
79        seg = kmalloc(sizeof(*seg) + alen,
80                         GFP_KERNEL);
81        if (seg == NULL) {
82            err = -ENOMEM;
83            goto out_err;
84        }
85        *pseg = seg;
86        seg->next = NULL;
87        if (copy_from_user(seg + 1, src, alen)) {
88            err = -EFAULT;
89            goto out_err;
90        }
91        pseg = &seg->next;
92        len -= alen;
93        src = ((char __user *)src) + alen;
94    }
95
96    err = security_msg_msg_alloc(msg);
97    if (err)
98        goto out_err;
99
100    return msg;
101
102out_err:
103    free_msg(msg);
104    return ERR_PTR(err);
105}
106
107int store_msg(void __user *dest, struct msg_msg *msg, int len)
108{
109    int alen;
110    struct msg_msgseg *seg;
111
112    alen = len;
113    if (alen > DATALEN_MSG)
114        alen = DATALEN_MSG;
115    if (copy_to_user(dest, msg + 1, alen))
116        return -1;
117
118    len -= alen;
119    dest = ((char __user *)dest) + alen;
120    seg = msg->next;
121    while (len > 0) {
122        alen = len;
123        if (alen > DATALEN_SEG)
124            alen = DATALEN_SEG;
125        if (copy_to_user(dest, seg + 1, alen))
126            return -1;
127        len -= alen;
128        dest = ((char __user *)dest) + alen;
129        seg = seg->next;
130    }
131    return 0;
132}
133
134void free_msg(struct msg_msg *msg)
135{
136    struct msg_msgseg *seg;
137
138    security_msg_msg_free(msg);
139
140    seg = msg->next;
141    kfree(msg);
142    while (seg != NULL) {
143        struct msg_msgseg *tmp = seg->next;
144        kfree(seg);
145        seg = tmp;
146    }
147}
148

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