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#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