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