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
  21 DEFINE_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  */
  28 struct ipc_namespace init_ipc_ns = {
  29         .count          = ATOMIC_INIT(1),
  30         .user_ns = &init_user_ns,
  31 };
  32
  33 atomic_t nr_ipc_ns = ATOMIC_INIT(1);
  34
  35 struct 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
  43 struct 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
  97 out_err:
  98         free_msg(msg);
  99         return ERR_PTR(err);
 100 }
 101
 102 int 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
 129 void 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 }