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/msg.h>
  17 #include <linux/ipc_namespace.h>
  18 #include <linux/utsname.h>
  19 #include <asm/uaccess.h>
  20
  21 #include "util.h"
  22
  23 DEFINE_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  */
  30 struct ipc_namespace init_ipc_ns = {
  31         .count          = ATOMIC_INIT(1),
  32         .user_ns = &init_user_ns,
  33 };
  34
  35 atomic_t nr_ipc_ns = ATOMIC_INIT(1);
  36
  37 struct 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
  45 struct 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
  99 out_err:
 100         free_msg(msg);
 101         return ERR_PTR(err);
 102 }
 103
 104 int 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
 131 void 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 }