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_set_mtime_to_ts(inode, inode_set_ctime_current(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};
115