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 <linux/proc_ns.h>
  20 #include <linux/uaccess.h>
  21
  22 #include "util.h"
  23
  24 DEFINE_SPINLOCK(mq_lock);
  25
  26 /*
  27  * The next 2 defines are here bc this is the only file
  28  * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
  29  * and not CONFIG_IPC_NS.
  30  */
  31 struct ipc_namespace init_ipc_ns = {
  32         .count          = ATOMIC_INIT(1),
  33         .user_ns = &init_user_ns,
  34         .ns.inum = PROC_IPC_INIT_INO,
  35 #ifdef CONFIG_IPC_NS
  36         .ns.ops = &ipcns_operations,
  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     ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
  48 #define DATALEN_SEG     ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
  49
  50
  51 static struct msg_msg *alloc_msg(size_t len)
  52 {
  53         struct msg_msg *msg;
  54         struct msg_msgseg **pseg;
  55         size_t alen;
  56
  57         alen = min(len, DATALEN_MSG);
  58         msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
  59         if (msg == NULL)
  60                 return NULL;
  61
  62         msg->next = NULL;
  63         msg->security = NULL;
  64
  65         len -= alen;
  66         pseg = &msg->next;
  67         while (len > 0) {
  68                 struct msg_msgseg *seg;
  69                 alen = min(len, DATALEN_SEG);
  70                 seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL);
  71                 if (seg == NULL)
  72                         goto out_err;
  73                 *pseg = seg;
  74                 seg->next = NULL;
  75                 pseg = &seg->next;
  76                 len -= alen;
  77         }
  78
  79         return msg;
  80
  81 out_err:
  82         free_msg(msg);
  83         return NULL;
  84 }
  85
  86 struct msg_msg *load_msg(const void __user *src, size_t len)
  87 {
  88         struct msg_msg *msg;
  89         struct msg_msgseg *seg;
  90         int err = -EFAULT;
  91         size_t alen;
  92
  93         msg = alloc_msg(len);
  94         if (msg == NULL)
  95                 return ERR_PTR(-ENOMEM);
  96
  97         alen = min(len, DATALEN_MSG);
  98         if (copy_from_user(msg + 1, src, alen))
  99                 goto out_err;
 100
 101         for (seg = msg->next; seg != NULL; seg = seg->next) {
 102                 len -= alen;
 103                 src = (char __user *)src + alen;
 104                 alen = min(len, DATALEN_SEG);
 105                 if (copy_from_user(seg + 1, src, alen))
 106                         goto out_err;
 107         }
 108
 109         err = security_msg_msg_alloc(msg);
 110         if (err)
 111                 goto out_err;
 112
 113         return msg;
 114
 115 out_err:
 116         free_msg(msg);
 117         return ERR_PTR(err);
 118 }
 119 #ifdef CONFIG_CHECKPOINT_RESTORE
 120 struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 121 {
 122         struct msg_msgseg *dst_pseg, *src_pseg;
 123         size_t len = src->m_ts;
 124         size_t alen;
 125
 126         BUG_ON(dst == NULL);
 127         if (src->m_ts > dst->m_ts)
 128                 return ERR_PTR(-EINVAL);
 129
 130         alen = min(len, DATALEN_MSG);
 131         memcpy(dst + 1, src + 1, alen);
 132
 133         for (dst_pseg = dst->next, src_pseg = src->next;
 134              src_pseg != NULL;
 135              dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
 136
 137                 len -= alen;
 138                 alen = min(len, DATALEN_SEG);
 139                 memcpy(dst_pseg + 1, src_pseg + 1, alen);
 140         }
 141
 142         dst->m_type = src->m_type;
 143         dst->m_ts = src->m_ts;
 144
 145         return dst;
 146 }
 147 #else
 148 struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 149 {
 150         return ERR_PTR(-ENOSYS);
 151 }
 152 #endif
 153 int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
 154 {
 155         size_t alen;
 156         struct msg_msgseg *seg;
 157
 158         alen = min(len, DATALEN_MSG);
 159         if (copy_to_user(dest, msg + 1, alen))
 160                 return -1;
 161
 162         for (seg = msg->next; seg != NULL; seg = seg->next) {
 163                 len -= alen;
 164                 dest = (char __user *)dest + alen;
 165                 alen = min(len, DATALEN_SEG);
 166                 if (copy_to_user(dest, seg + 1, alen))
 167                         return -1;
 168         }
 169         return 0;
 170 }
 171
 172 void free_msg(struct msg_msg *msg)
 173 {
 174         struct msg_msgseg *seg;
 175
 176         security_msg_msg_free(msg);
 177
 178         seg = msg->next;
 179         kfree(msg);
 180         while (seg != NULL) {
 181                 struct msg_msgseg *tmp = seg->next;
 182                 kfree(seg);
 183                 seg = tmp;
 184         }
 185 }