qubes-linux-kernel/u2mfn/u2mfn.c
Marek Marczykowski c0a145a129 u2mfn: change default /proc/u2mfn permissions
It is set to 666 by init scripts anyway. Set defaults here, as scripts
are not working in all the cases (DispVM audio problem).
2013-04-17 13:16:37 +02:00

168 lines
3.9 KiB
C

/*
* The Qubes OS Project, http://www.qubes-os.org
*
* Copyright (C) 2010 Rafal Wojtczuk <rafal@invisiblethingslab.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#include <linux/module.h>
#include <linux/version.h>
#include <linux/proc_fs.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/sched.h>
#ifndef FOREIGN_FRAME_BIT
#include <xen/page.h>
#endif
#include <linux/highmem.h>
#include "/usr/include/u2mfn-kernel.h"
#if LINUX_VERSION_CODE < KERNEL_VERSION(3,0,0)
static inline unsigned long virt_to_phys(volatile void *address)
{
return __pa((unsigned long) address);
}
#endif
#ifdef virt_to_mfn
#define VIRT_TO_MFN virt_to_mfn
#else
extern unsigned long *phys_to_machine_mapping;
static inline unsigned long VIRT_TO_MFN(void *addr)
{
unsigned int pfn = virt_to_phys(addr) >> PAGE_SHIFT;
return phys_to_machine_mapping[pfn] & ~FOREIGN_FRAME_BIT;
}
#endif
/// User virtual address to mfn translator
/**
\param cmd ignored
\param data the user-specified address
\return mfn corresponding to "data" argument, or -1 on error
*/
static long u2mfn_ioctl(struct file *f, unsigned int cmd,
unsigned long data)
{
struct page *user_page;
void *kaddr;
int ret;
if (_IOC_TYPE(cmd) != U2MFN_MAGIC) {
printk("Qubes u2mfn: wrong IOCTL magic");
return -ENOTTY;
}
switch (cmd) {
case U2MFN_GET_MFN_FOR_PAGE:
down_read(&current->mm->mmap_sem);
ret = get_user_pages
(current, current->mm, data, 1, 1, 0, &user_page, 0);
up_read(&current->mm->mmap_sem);
if (ret != 1) {
printk("U2MFN_GET_MFN_FOR_PAGE: get_user_pages failed, ret=0x%x\n", ret);
return -1;
}
kaddr = kmap(user_page);
ret = VIRT_TO_MFN(kaddr);
kunmap(user_page);
put_page(user_page);
break;
case U2MFN_GET_LAST_MFN:
if (f->private_data)
ret = VIRT_TO_MFN(f->private_data);
else
ret = 0;
break;
default:
printk("Qubes u2mfn: wrong ioctl passed!\n");
return -ENOTTY;
}
return ret;
}
static int u2mfn_mmap(struct file *f, struct vm_area_struct *vma)
{
int ret;
char *kbuf;
long length = vma->vm_end - vma->vm_start;
printk("u2mfn_mmap: entering, private=%p\n", f->private_data);
if (f->private_data)
return -EBUSY;
if (length != PAGE_SIZE)
return -EINVAL;
kbuf = (char *) __get_free_page(GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
f->private_data = kbuf;
ret = remap_pfn_range(vma, vma->vm_start,
virt_to_phys(kbuf) >> PAGE_SHIFT,
length, vma->vm_page_prot);
printk("u2mfn_mmap: calling remap return %d\n", ret);
if (ret)
return ret;
return 0;
}
static int u2mfn_release(struct inode *i, struct file *f)
{
printk("u2mfn_release, priv=%p\n", f->private_data);
if (f->private_data)
__free_page(f->private_data);
f->private_data = NULL;
return 0;
}
static struct file_operations u2mfn_fops = {
.unlocked_ioctl = u2mfn_ioctl,
.mmap = u2mfn_mmap,
.release = u2mfn_release
};
/// u2mfn module registration
/**
tries to register "/proc/u2mfn" pseudofile
*/
static int u2mfn_init(void)
{
struct proc_dir_entry *u2mfn_node =
proc_create_data("u2mfn", 0666, NULL,
&u2mfn_fops, 0);
if (!u2mfn_node)
return -1;
return 0;
}
static void u2mfn_exit(void)
{
remove_proc_entry("u2mfn", 0);
}
module_init(u2mfn_init);
module_exit(u2mfn_exit);
MODULE_LICENSE("GPL");