msgutil.c

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/*
 * linux/ipc/msgutil.c
 * Copyright (C) 1999, 2004 Manfred Spraul
 *
 * This file is released under GNU General Public Licence version 2 or
 * (at your option) any later version.
 *
 * See the file COPYING for more details.
 */

#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/security.h>
#include <linux/slab.h>
#include <linux/ipc.h>
#include <linux/msg.h>
#include <linux/ipc_namespace.h>
#include <linux/utsname.h>
#include <asm/uaccess.h>

#include "util.h"

DEFINE_SPINLOCK(mq_lock);

/*
 * The next 2 defines are here bc this is the only file
 * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
 * and not CONFIG_IPC_NS.
 */
struct ipc_namespace init_ipc_ns = {
    .count      = ATOMIC_INIT(1),
    .user_ns = &init_user_ns,
};

atomic_t nr_ipc_ns = ATOMIC_INIT(1);

struct msg_msgseg {
    struct msg_msgseg* next;
    /* the next part of the message follows immediately */
};

#define DATALEN_MSG (PAGE_SIZE-sizeof(struct msg_msg))
#define DATALEN_SEG (PAGE_SIZE-sizeof(struct msg_msgseg))

struct msg_msg *load_msg(const void __user *src, int len)
{
    struct msg_msg *msg;
    struct msg_msgseg **pseg;
    int err;
    int alen;

    alen = len;
    if (alen > DATALEN_MSG)
        alen = DATALEN_MSG;

    msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
    if (msg == NULL)
        return ERR_PTR(-ENOMEM);

    msg->next = NULL;
    msg->security = NULL;

    if (copy_from_user(msg + 1, src, alen)) {
        err = -EFAULT;
        goto out_err;
    }

    len -= alen;
    src = ((char __user *)src) + alen;
    pseg = &msg->next;
    while (len > 0) {
        struct msg_msgseg *seg;
        alen = len;
        if (alen > DATALEN_SEG)
            alen = DATALEN_SEG;
        seg = kmalloc(sizeof(*seg) + alen,
                         GFP_KERNEL);
        if (seg == NULL) {
            err = -ENOMEM;
            goto out_err;
        }
        *pseg = seg;
        seg->next = NULL;
        if (copy_from_user(seg + 1, src, alen)) {
            err = -EFAULT;
            goto out_err;
        }
        pseg = &seg->next;
        len -= alen;
        src = ((char __user *)src) + alen;
    }

    err = security_msg_msg_alloc(msg);
    if (err)
        goto out_err;

    return msg;

out_err:
    free_msg(msg);
    return ERR_PTR(err);
}

int store_msg(void __user *dest, struct msg_msg *msg, int len)
{
    int alen;
    struct msg_msgseg *seg;

    alen = len;
    if (alen > DATALEN_MSG)
        alen = DATALEN_MSG;
    if (copy_to_user(dest, msg + 1, alen))
        return -1;

    len -= alen;
    dest = ((char __user *)dest) + alen;
    seg = msg->next;
    while (len > 0) {
        alen = len;
        if (alen > DATALEN_SEG)
            alen = DATALEN_SEG;
        if (copy_to_user(dest, seg + 1, alen))
            return -1;
        len -= alen;
        dest = ((char __user *)dest) + alen;
        seg = seg->next;
    }
    return 0;
}

void free_msg(struct msg_msg *msg)
{
    struct msg_msgseg *seg;

    security_msg_msg_free(msg);

    seg = msg->next;
    kfree(msg);
    while (seg != NULL) {
        struct msg_msgseg *tmp = seg->next;
        kfree(seg);
        seg = tmp;
    }
}