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 /*
  22  * The next 2 defines are here bc this is the only file
  23  * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
  24  * and not CONFIG_IPC_NS.
  25  */
  26 struct ipc_namespace init_ipc_ns = {
  27         .kref = {
  28                 /* It's not for this patch to change, but should this be 1? */
  29                 .refcount       = ATOMIC_INIT(2),
  30         },
  31 #ifdef CONFIG_POSIX_MQUEUE
  32         .mq_mnt          = NULL,
  33         .mq_queues_count = 0,
  34         .mq_queues_max   = DFLT_QUEUESMAX,
  35         .mq_msg_max      = DFLT_MSGMAX,
  36         .mq_msgsize_max  = DFLT_MSGSIZEMAX,
  37 #endif
  38 };
  39
  40 atomic_t nr_ipc_ns = ATOMIC_INIT(1);
  41
  42 struct msg_msgseg {
  43         struct msg_msgseg* next;
  44         /* the next part of the message follows immediately */
  45 };
  46
  47 #define DATALEN_MSG     (PAGE_SIZE-sizeof(struct msg_msg))
  48 #define DATALEN_SEG     (PAGE_SIZE-sizeof(struct msg_msgseg))
  49
  50 struct msg_msg *load_msg(const void __user *src, int len)
  51 {
  52         struct msg_msg *msg;
  53         struct msg_msgseg **pseg;
  54         int err;
  55         int alen;
  56
  57         alen = len;
  58         if (alen > DATALEN_MSG)
  59                 alen = DATALEN_MSG;
  60
  61         msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
  62         if (msg == NULL)
  63                 return ERR_PTR(-ENOMEM);
  64
  65         msg->next = NULL;
  66         msg->security = NULL;
  67
  68         if (copy_from_user(msg + 1, src, alen)) {
  69                 err = -EFAULT;
  70                 goto out_err;
  71         }
  72
  73         len -= alen;
  74         src = ((char __user *)src) + alen;
  75         pseg = &msg->next;
  76         while (len > 0) {
  77                 struct msg_msgseg *seg;
  78                 alen = len;
  79                 if (alen > DATALEN_SEG)
  80                         alen = DATALEN_SEG;
  81                 seg = kmalloc(sizeof(*seg) + alen,
  82                                                  GFP_KERNEL);
  83                 if (seg == NULL) {
  84                         err = -ENOMEM;
  85                         goto out_err;
  86                 }
  87                 *pseg = seg;
  88                 seg->next = NULL;
  89                 if (copy_from_user(seg + 1, src, alen)) {
  90                         err = -EFAULT;
  91                         goto out_err;
  92                 }
  93                 pseg = &seg->next;
  94                 len -= alen;
  95                 src = ((char __user *)src) + alen;
  96         }
  97
  98         err = security_msg_msg_alloc(msg);
  99         if (err)
 100                 goto out_err;
 101
 102         return msg;
 103
 104 out_err:
 105         free_msg(msg);
 106         return ERR_PTR(err);
 107 }
 108
 109 int store_msg(void __user *dest, struct msg_msg *msg, int len)
 110 {
 111         int alen;
 112         struct msg_msgseg *seg;
 113
 114         alen = len;
 115         if (alen > DATALEN_MSG)
 116                 alen = DATALEN_MSG;
 117         if (copy_to_user(dest, msg + 1, alen))
 118                 return -1;
 119
 120         len -= alen;
 121         dest = ((char __user *)dest) + alen;
 122         seg = msg->next;
 123         while (len > 0) {
 124                 alen = len;
 125                 if (alen > DATALEN_SEG)
 126                         alen = DATALEN_SEG;
 127                 if (copy_to_user(dest, seg + 1, alen))
 128                         return -1;
 129                 len -= alen;
 130                 dest = ((char __user *)dest) + alen;
 131                 seg = seg->next;
 132         }
 133         return 0;
 134 }
 135
 136 void free_msg(struct msg_msg *msg)
 137 {
 138         struct msg_msgseg *seg;
 139
 140         security_msg_msg_free(msg);
 141
 142         seg = msg->next;
 143         kfree(msg);
 144         while (seg != NULL) {
 145                 struct msg_msgseg *tmp = seg->next;
 146                 kfree(seg);
 147                 seg = tmp;
 148         }
 149 }