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/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        .user_ns = &init_user_ns,
  36};
  37
  38atomic_t nr_ipc_ns = ATOMIC_INIT(1);
  39
  40struct msg_msgseg {
  41        struct msg_msgseg* next;
  42        /* the next part of the message follows immediately */
  43};
  44
  45#define DATALEN_MSG     (PAGE_SIZE-sizeof(struct msg_msg))
  46#define DATALEN_SEG     (PAGE_SIZE-sizeof(struct msg_msgseg))
  47
  48struct msg_msg *load_msg(const void __user *src, int len)
  49{
  50        struct msg_msg *msg;
  51        struct msg_msgseg **pseg;
  52        int err;
  53        int alen;
  54
  55        alen = len;
  56        if (alen > DATALEN_MSG)
  57                alen = DATALEN_MSG;
  58
  59        msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
  60        if (msg == NULL)
  61                return ERR_PTR(-ENOMEM);
  62
  63        msg->next = NULL;
  64        msg->security = NULL;
  65
  66        if (copy_from_user(msg + 1, src, alen)) {
  67                err = -EFAULT;
  68                goto out_err;
  69        }
  70
  71        len -= alen;
  72        src = ((char __user *)src) + alen;
  73        pseg = &msg->next;
  74        while (len > 0) {
  75                struct msg_msgseg *seg;
  76                alen = len;
  77                if (alen > DATALEN_SEG)
  78                        alen = DATALEN_SEG;
  79                seg = kmalloc(sizeof(*seg) + alen,
  80                                                 GFP_KERNEL);
  81                if (seg == NULL) {
  82                        err = -ENOMEM;
  83                        goto out_err;
  84                }
  85                *pseg = seg;
  86                seg->next = NULL;
  87                if (copy_from_user(seg + 1, src, alen)) {
  88                        err = -EFAULT;
  89                        goto out_err;
  90                }
  91                pseg = &seg->next;
  92                len -= alen;
  93                src = ((char __user *)src) + alen;
  94        }
  95
  96        err = security_msg_msg_alloc(msg);
  97        if (err)
  98                goto out_err;
  99
 100        return msg;
 101
 102out_err:
 103        free_msg(msg);
 104        return ERR_PTR(err);
 105}
 106
 107int store_msg(void __user *dest, struct msg_msg *msg, int len)
 108{
 109        int alen;
 110        struct msg_msgseg *seg;
 111
 112        alen = len;
 113        if (alen > DATALEN_MSG)
 114                alen = DATALEN_MSG;
 115        if (copy_to_user(dest, msg + 1, alen))
 116                return -1;
 117
 118        len -= alen;
 119        dest = ((char __user *)dest) + alen;
 120        seg = msg->next;
 121        while (len > 0) {
 122                alen = len;
 123                if (alen > DATALEN_SEG)
 124                        alen = DATALEN_SEG;
 125                if (copy_to_user(dest, seg + 1, alen))
 126                        return -1;
 127                len -= alen;
 128                dest = ((char __user *)dest) + alen;
 129                seg = seg->next;
 130        }
 131        return 0;
 132}
 133
 134void free_msg(struct msg_msg *msg)
 135{
 136        struct msg_msgseg *seg;
 137
 138        security_msg_msg_free(msg);
 139
 140        seg = msg->next;
 141        kfree(msg);
 142        while (seg != NULL) {
 143                struct msg_msgseg *tmp = seg->next;
 144                kfree(seg);
 145                seg = tmp;
 146        }
 147}
 148
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