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 <asm/uaccess.h>
  20
  21#include "util.h"
  22
  23DEFINE_SPINLOCK(mq_lock);
  24
  25/*
  26 * The next 2 defines are here bc this is the only file
  27 * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
  28 * and not CONFIG_IPC_NS.
  29 */
  30struct ipc_namespace init_ipc_ns = {
  31        .count          = ATOMIC_INIT(1),
  32        .user_ns = &init_user_ns,
  33};
  34
  35atomic_t nr_ipc_ns = ATOMIC_INIT(1);
  36
  37struct msg_msgseg {
  38        struct msg_msgseg* next;
  39        /* the next part of the message follows immediately */
  40};
  41
  42#define DATALEN_MSG     (PAGE_SIZE-sizeof(struct msg_msg))
  43#define DATALEN_SEG     (PAGE_SIZE-sizeof(struct msg_msgseg))
  44
  45struct msg_msg *load_msg(const void __user *src, int len)
  46{
  47        struct msg_msg *msg;
  48        struct msg_msgseg **pseg;
  49        int err;
  50        int alen;
  51
  52        alen = len;
  53        if (alen > DATALEN_MSG)
  54                alen = DATALEN_MSG;
  55
  56        msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
  57        if (msg == NULL)
  58                return ERR_PTR(-ENOMEM);
  59
  60        msg->next = NULL;
  61        msg->security = NULL;
  62
  63        if (copy_from_user(msg + 1, src, alen)) {
  64                err = -EFAULT;
  65                goto out_err;
  66        }
  67
  68        len -= alen;
  69        src = ((char __user *)src) + alen;
  70        pseg = &msg->next;
  71        while (len > 0) {
  72                struct msg_msgseg *seg;
  73                alen = len;
  74                if (alen > DATALEN_SEG)
  75                        alen = DATALEN_SEG;
  76                seg = kmalloc(sizeof(*seg) + alen,
  77                                                 GFP_KERNEL);
  78                if (seg == NULL) {
  79                        err = -ENOMEM;
  80                        goto out_err;
  81                }
  82                *pseg = seg;
  83                seg->next = NULL;
  84                if (copy_from_user(seg + 1, src, alen)) {
  85                        err = -EFAULT;
  86                        goto out_err;
  87                }
  88                pseg = &seg->next;
  89                len -= alen;
  90                src = ((char __user *)src) + alen;
  91        }
  92
  93        err = security_msg_msg_alloc(msg);
  94        if (err)
  95                goto out_err;
  96
  97        return msg;
  98
  99out_err:
 100        free_msg(msg);
 101        return ERR_PTR(err);
 102}
 103
 104int store_msg(void __user *dest, struct msg_msg *msg, int len)
 105{
 106        int alen;
 107        struct msg_msgseg *seg;
 108
 109        alen = len;
 110        if (alen > DATALEN_MSG)
 111                alen = DATALEN_MSG;
 112        if (copy_to_user(dest, msg + 1, alen))
 113                return -1;
 114
 115        len -= alen;
 116        dest = ((char __user *)dest) + alen;
 117        seg = msg->next;
 118        while (len > 0) {
 119                alen = len;
 120                if (alen > DATALEN_SEG)
 121                        alen = DATALEN_SEG;
 122                if (copy_to_user(dest, seg + 1, alen))
 123                        return -1;
 124                len -= alen;
 125                dest = ((char __user *)dest) + alen;
 126                seg = seg->next;
 127        }
 128        return 0;
 129}
 130
 131void free_msg(struct msg_msg *msg)
 132{
 133        struct msg_msgseg *seg;
 134
 135        security_msg_msg_free(msg);
 136
 137        seg = msg->next;
 138        kfree(msg);
 139        while (seg != NULL) {
 140                struct msg_msgseg *tmp = seg->next;
 141                kfree(seg);
 142                seg = tmp;
 143        }
 144}
 145
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