LXR linux/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
  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          = REFCOUNT_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
  40struct msg_msgseg {
  41        struct msg_msgseg *next;
  42        /* the next part of the message follows immediately */
  43};
  44
  45#define DATALEN_MSG     ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
  46#define DATALEN_SEG     ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
  47
  48
  49static struct msg_msg *alloc_msg(size_t len)
  50{
  51        struct msg_msg *msg;
  52        struct msg_msgseg **pseg;
  53        size_t alen;
  54
  55        alen = min(len, DATALEN_MSG);
  56        msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL_ACCOUNT);
  57        if (msg == NULL)
  58                return NULL;
  59
  60        msg->next = NULL;
  61        msg->security = NULL;
  62
  63        len -= alen;
  64        pseg = &msg->next;
  65        while (len > 0) {
  66                struct msg_msgseg *seg;
  67                alen = min(len, DATALEN_SEG);
  68                seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT);
  69                if (seg == NULL)
  70                        goto out_err;
  71                *pseg = seg;
  72                seg->next = NULL;
  73                pseg = &seg->next;
  74                len -= alen;
  75        }
  76
  77        return msg;
  78
  79out_err:
  80        free_msg(msg);
  81        return NULL;
  82}
  83
  84struct msg_msg *load_msg(const void __user *src, size_t len)
  85{
  86        struct msg_msg *msg;
  87        struct msg_msgseg *seg;
  88        int err = -EFAULT;
  89        size_t alen;
  90
  91        msg = alloc_msg(len);
  92        if (msg == NULL)
  93                return ERR_PTR(-ENOMEM);
  94
  95        alen = min(len, DATALEN_MSG);
  96        if (copy_from_user(msg + 1, src, alen))
  97                goto out_err;
  98
  99        for (seg = msg->next; seg != NULL; seg = seg->next) {
 100                len -= alen;
 101                src = (char __user *)src + alen;
 102                alen = min(len, DATALEN_SEG);
 103                if (copy_from_user(seg + 1, src, alen))
 104                        goto out_err;
 105        }
 106
 107        err = security_msg_msg_alloc(msg);
 108        if (err)
 109                goto out_err;
 110
 111        return msg;
 112
 113out_err:
 114        free_msg(msg);
 115        return ERR_PTR(err);
 116}
 117#ifdef CONFIG_CHECKPOINT_RESTORE
 118struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 119{
 120        struct msg_msgseg *dst_pseg, *src_pseg;
 121        size_t len = src->m_ts;
 122        size_t alen;
 123
 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, 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
 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