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         .proc_inum = PROC_IPC_INIT_INO,
  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     ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
  45 #define DATALEN_SEG     ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
  46
  47
  48 static struct msg_msg *alloc_msg(size_t len)
  49 {
  50         struct msg_msg *msg;
  51         struct msg_msgseg **pseg;
  52         size_t alen;
  53
  54         alen = min(len, DATALEN_MSG);
  55         msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
  56         if (msg == NULL)
  57                 return NULL;
  58
  59         msg->next = NULL;
  60         msg->security = NULL;
  61
  62         len -= alen;
  63         pseg = &msg->next;
  64         while (len > 0) {
  65                 struct msg_msgseg *seg;
  66                 alen = min(len, DATALEN_SEG);
  67                 seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL);
  68                 if (seg == NULL)
  69                         goto out_err;
  70                 *pseg = seg;
  71                 seg->next = NULL;
  72                 pseg = &seg->next;
  73                 len -= alen;
  74         }
  75
  76         return msg;
  77
  78 out_err:
  79         free_msg(msg);
  80         return NULL;
  81 }
  82
  83 struct msg_msg *load_msg(const void __user *src, size_t len)
  84 {
  85         struct msg_msg *msg;
  86         struct msg_msgseg *seg;
  87         int err = -EFAULT;
  88         size_t alen;
  89
  90         msg = alloc_msg(len);
  91         if (msg == NULL)
  92                 return ERR_PTR(-ENOMEM);
  93
  94         alen = min(len, DATALEN_MSG);
  95         if (copy_from_user(msg + 1, src, alen))
  96                 goto out_err;
  97
  98         for (seg = msg->next; seg != NULL; seg = seg->next) {
  99                 len -= alen;
 100                 src = (char __user *)src + alen;
 101                 alen = min(len, DATALEN_SEG);
 102                 if (copy_from_user(seg + 1, src, alen))
 103                         goto out_err;
 104         }
 105
 106         err = security_msg_msg_alloc(msg);
 107         if (err)
 108                 goto out_err;
 109
 110         return msg;
 111
 112 out_err:
 113         free_msg(msg);
 114         return ERR_PTR(err);
 115 }
 116 #ifdef CONFIG_CHECKPOINT_RESTORE
 117 struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 118 {
 119         struct msg_msgseg *dst_pseg, *src_pseg;
 120         size_t len = src->m_ts;
 121         size_t alen;
 122
 123         BUG_ON(dst == NULL);
 124         if (src->m_ts > dst->m_ts)
 125                 return ERR_PTR(-EINVAL);
 126
 127         alen = min(len, DATALEN_MSG);
 128         memcpy(dst + 1, src + 1, alen);
 129
 130         for (dst_pseg = dst->next, src_pseg = src->next;
 131              src_pseg != NULL;
 132              dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
 133
 134                 len -= alen;
 135                 alen = min(len, DATALEN_SEG);
 136                 memcpy(dst_pseg + 1, src_pseg + 1, alen);
 137         }
 138
 139         dst->m_type = src->m_type;
 140         dst->m_ts = src->m_ts;
 141
 142         return dst;
 143 }
 144 #else
 145 struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 146 {
 147         return ERR_PTR(-ENOSYS);
 148 }
 149 #endif
 150 int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
 151 {
 152         size_t alen;
 153         struct msg_msgseg *seg;
 154
 155         alen = min(len, DATALEN_MSG);
 156         if (copy_to_user(dest, msg + 1, alen))
 157                 return -1;
 158
 159         for (seg = msg->next; seg != NULL; seg = seg->next) {
 160                 len -= alen;
 161                 dest = (char __user *)dest + alen;
 162                 alen = min(len, DATALEN_SEG);
 163                 if (copy_to_user(dest, seg + 1, alen))
 164                         return -1;
 165         }
 166         return 0;
 167 }
 168
 169 void free_msg(struct msg_msg *msg)
 170 {
 171         struct msg_msgseg *seg;
 172
 173         security_msg_msg_free(msg);
 174
 175         seg = msg->next;
 176         kfree(msg);
 177         while (seg != NULL) {
 178                 struct msg_msgseg *tmp = seg->next;
 179                 kfree(seg);
 180                 seg = tmp;
 181         }
 182 }