linux/ipc/msgutil.c
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   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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