cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

file.c (2492B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (C) 2012 Red Hat, Inc.
      4 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
      5 */
      6
      7#include <linux/efi.h>
      8#include <linux/delay.h>
      9#include <linux/fs.h>
     10#include <linux/slab.h>
     11#include <linux/mount.h>
     12
     13#include "internal.h"
     14
     15static ssize_t efivarfs_file_write(struct file *file,
     16		const char __user *userbuf, size_t count, loff_t *ppos)
     17{
     18	struct efivar_entry *var = file->private_data;
     19	void *data;
     20	u32 attributes;
     21	struct inode *inode = file->f_mapping->host;
     22	unsigned long datasize = count - sizeof(attributes);
     23	ssize_t bytes;
     24	bool set = false;
     25
     26	if (count < sizeof(attributes))
     27		return -EINVAL;
     28
     29	if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
     30		return -EFAULT;
     31
     32	if (attributes & ~(EFI_VARIABLE_MASK))
     33		return -EINVAL;
     34
     35	data = memdup_user(userbuf + sizeof(attributes), datasize);
     36	if (IS_ERR(data))
     37		return PTR_ERR(data);
     38
     39	bytes = efivar_entry_set_get_size(var, attributes, &datasize,
     40					  data, &set);
     41	if (!set && bytes) {
     42		if (bytes == -ENOENT)
     43			bytes = -EIO;
     44		goto out;
     45	}
     46
     47	if (bytes == -ENOENT) {
     48		drop_nlink(inode);
     49		d_delete(file->f_path.dentry);
     50		dput(file->f_path.dentry);
     51	} else {
     52		inode_lock(inode);
     53		i_size_write(inode, datasize + sizeof(attributes));
     54		inode->i_mtime = current_time(inode);
     55		inode_unlock(inode);
     56	}
     57
     58	bytes = count;
     59
     60out:
     61	kfree(data);
     62
     63	return bytes;
     64}
     65
     66static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
     67		size_t count, loff_t *ppos)
     68{
     69	struct efivar_entry *var = file->private_data;
     70	unsigned long datasize = 0;
     71	u32 attributes;
     72	void *data;
     73	ssize_t size = 0;
     74	int err;
     75
     76	while (!__ratelimit(&file->f_cred->user->ratelimit))
     77		msleep(50);
     78
     79	err = efivar_entry_size(var, &datasize);
     80
     81	/*
     82	 * efivarfs represents uncommitted variables with
     83	 * zero-length files. Reading them should return EOF.
     84	 */
     85	if (err == -ENOENT)
     86		return 0;
     87	else if (err)
     88		return err;
     89
     90	data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
     91
     92	if (!data)
     93		return -ENOMEM;
     94
     95	size = efivar_entry_get(var, &attributes, &datasize,
     96				data + sizeof(attributes));
     97	if (size)
     98		goto out_free;
     99
    100	memcpy(data, &attributes, sizeof(attributes));
    101	size = simple_read_from_buffer(userbuf, count, ppos,
    102				       data, datasize + sizeof(attributes));
    103out_free:
    104	kfree(data);
    105
    106	return size;
    107}
    108
    109const struct file_operations efivarfs_file_operations = {
    110	.open	= simple_open,
    111	.read	= efivarfs_file_read,
    112	.write	= efivarfs_file_write,
    113	.llseek	= no_llseek,
    114};