linux/ipc/msgutil.c
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   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
  24DEFINE_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 */
  31struct 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
  37atomic_t nr_ipc_ns = ATOMIC_INIT(1);
  38
  39struct msg_msgseg {
  40        struct msg_msgseg *next;
  41        /* the next part of the message follows immediately */
  42};
  43
  44#define DATALEN_MSG     (int)(PAGE_SIZE-sizeof(struct msg_msg))
  45#define DATALEN_SEG     (int)(PAGE_SIZE-sizeof(struct msg_msgseg))
  46
  47
  48static struct msg_msg *alloc_msg(int len)
  49{
  50        struct msg_msg *msg;
  51        struct msg_msgseg **pseg;
  52        int 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
  78out_err:
  79        free_msg(msg);
  80        return NULL;
  81}
  82
  83struct msg_msg *load_msg(const void __user *src, int len)
  84{
  85        struct msg_msg *msg;
  86        struct msg_msgseg *seg;
  87        int err = -EFAULT;
  88        int 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
 112out_err:
 113        free_msg(msg);
 114        return ERR_PTR(err);
 115}
 116#ifdef CONFIG_CHECKPOINT_RESTORE
 117struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 118{
 119        struct msg_msgseg *dst_pseg, *src_pseg;
 120        int len = src->m_ts;
 121        int 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
 145struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 146{
 147        return ERR_PTR(-ENOSYS);
 148}
 149#endif
 150int store_msg(void __user *dest, struct msg_msg *msg, int len)
 151{
 152        int 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
 169void 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}
 183
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