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};
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
106int store_msg(void __user *dest, struct msg_msg *msg, int len)
107{
108    int alen;
109    struct msg_msgseg *seg;
110
111    alen = len;
112    if (alen > DATALEN_MSG)
113        alen = DATALEN_MSG;
114    if (copy_to_user(dest, msg + 1, alen))
115        return -1;
116
117    len -= alen;
118    dest = ((char __user *)dest) + alen;
119    seg = msg->next;
120    while (len > 0) {
121        alen = len;
122        if (alen > DATALEN_SEG)
123            alen = DATALEN_SEG;
124        if (copy_to_user(dest, seg + 1, alen))
125            return -1;
126        len -= alen;
127        dest = ((char __user *)dest) + alen;
128        seg = seg->next;
129    }
130    return 0;
131}
132
133void free_msg(struct msg_msg *msg)
134{
135    struct msg_msgseg *seg;
136
137    security_msg_msg_free(msg);
138
139    seg = msg->next;
140    kfree(msg);
141    while (seg != NULL) {
142        struct msg_msgseg *tmp = seg->next;
143        kfree(seg);
144        seg = tmp;
145    }
146}
147

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