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 #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
  37 atomic_t nr_ipc_ns = ATOMIC_INIT(1);
  38
  39 struct 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
  47 struct 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
 101 out_err:
 102         free_msg(msg);
 103         return ERR_PTR(err);
 104 }
 105
 106 int 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
 133 void 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 }