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 #include <linux/sched.h>
  22
  23 #include "util.h"
  24
  25 DEFINE_SPINLOCK(mq_lock);
  26
  27 /*
  28  * The next 2 defines are here bc this is the only file
  29  * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
  30  * and not CONFIG_IPC_NS.
  31  */
  32 struct ipc_namespace init_ipc_ns = {
  33         .count          = REFCOUNT_INIT(1),
  34         .user_ns = &init_user_ns,
  35         .ns.inum = PROC_IPC_INIT_INO,
  36 #ifdef CONFIG_IPC_NS
  37         .ns.ops = &ipcns_operations,
  38 #endif
  39 };
  40
  41 struct msg_msgseg {
  42         struct msg_msgseg *next;
  43         /* the next part of the message follows immediately */
  44 };
  45
  46 #define DATALEN_MSG     ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
  47 #define DATALEN_SEG     ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
  48
  49
  50 static struct msg_msg *alloc_msg(size_t len)
  51 {
  52         struct msg_msg *msg;
  53         struct msg_msgseg **pseg;
  54         size_t alen;
  55
  56         alen = min(len, DATALEN_MSG);
  57         msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL_ACCOUNT);
  58         if (msg == NULL)
  59                 return NULL;
  60
  61         msg->next = NULL;
  62         msg->security = NULL;
  63
  64         len -= alen;
  65         pseg = &msg->next;
  66         while (len > 0) {
  67                 struct msg_msgseg *seg;
  68
  69                 cond_resched();
  70
  71                 alen = min(len, DATALEN_SEG);
  72                 seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT);
  73                 if (seg == NULL)
  74                         goto out_err;
  75                 *pseg = seg;
  76                 seg->next = NULL;
  77                 pseg = &seg->next;
  78                 len -= alen;
  79         }
  80
  81         return msg;
  82
  83 out_err:
  84         free_msg(msg);
  85         return NULL;
  86 }
  87
  88 struct msg_msg *load_msg(const void __user *src, size_t len)
  89 {
  90         struct msg_msg *msg;
  91         struct msg_msgseg *seg;
  92         int err = -EFAULT;
  93         size_t alen;
  94
  95         msg = alloc_msg(len);
  96         if (msg == NULL)
  97                 return ERR_PTR(-ENOMEM);
  98
  99         alen = min(len, DATALEN_MSG);
 100         if (copy_from_user(msg + 1, src, alen))
 101                 goto out_err;
 102
 103         for (seg = msg->next; seg != NULL; seg = seg->next) {
 104                 len -= alen;
 105                 src = (char __user *)src + alen;
 106                 alen = min(len, DATALEN_SEG);
 107                 if (copy_from_user(seg + 1, src, alen))
 108                         goto out_err;
 109         }
 110
 111         err = security_msg_msg_alloc(msg);
 112         if (err)
 113                 goto out_err;
 114
 115         return msg;
 116
 117 out_err:
 118         free_msg(msg);
 119         return ERR_PTR(err);
 120 }
 121 #ifdef CONFIG_CHECKPOINT_RESTORE
 122 struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 123 {
 124         struct msg_msgseg *dst_pseg, *src_pseg;
 125         size_t len = src->m_ts;
 126         size_t alen;
 127
 128         if (src->m_ts > dst->m_ts)
 129                 return ERR_PTR(-EINVAL);
 130
 131         alen = min(len, DATALEN_MSG);
 132         memcpy(dst + 1, src + 1, alen);
 133
 134         for (dst_pseg = dst->next, src_pseg = src->next;
 135              src_pseg != NULL;
 136              dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
 137
 138                 len -= alen;
 139                 alen = min(len, DATALEN_SEG);
 140                 memcpy(dst_pseg + 1, src_pseg + 1, alen);
 141         }
 142
 143         dst->m_type = src->m_type;
 144         dst->m_ts = src->m_ts;
 145
 146         return dst;
 147 }
 148 #else
 149 struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 150 {
 151         return ERR_PTR(-ENOSYS);
 152 }
 153 #endif
 154 int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
 155 {
 156         size_t alen;
 157         struct msg_msgseg *seg;
 158
 159         alen = min(len, DATALEN_MSG);
 160         if (copy_to_user(dest, msg + 1, alen))
 161                 return -1;
 162
 163         for (seg = msg->next; seg != NULL; seg = seg->next) {
 164                 len -= alen;
 165                 dest = (char __user *)dest + alen;
 166                 alen = min(len, DATALEN_SEG);
 167                 if (copy_to_user(dest, seg + 1, alen))
 168                         return -1;
 169         }
 170         return 0;
 171 }
 172
 173 void free_msg(struct msg_msg *msg)
 174 {
 175         struct msg_msgseg *seg;
 176
 177         security_msg_msg_free(msg);
 178
 179         seg = msg->next;
 180         kfree(msg);
 181         while (seg != NULL) {
 182                 struct msg_msgseg *tmp = seg->next;
 183
 184                 cond_resched();
 185                 kfree(seg);
 186                 seg = tmp;
 187         }
 188 }