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(to: &attributes, from: userbuf, n: 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(ptr: data))
37 return PTR_ERR(ptr: data);
38
39 inode_lock(inode);
40 if (var->removed) {
41 /*
42 * file got removed; don't allow a set. Caused by an
43 * unsuccessful create or successful delete write
44 * racing with us.
45 */
46 bytes = -EIO;
47 goto out;
48 }
49
50 bytes = efivar_entry_set_get_size(entry: var, attributes, size: &datasize,
51 data, set: &set);
52 if (!set) {
53 if (bytes == -ENOENT)
54 bytes = -EIO;
55 goto out;
56 }
57
58 if (bytes == -ENOENT) {
59 /*
60 * zero size signals to release that the write deleted
61 * the variable
62 */
63 i_size_write(inode, i_size: 0);
64 } else {
65 i_size_write(inode, i_size: datasize + sizeof(attributes));
66 inode_set_mtime_to_ts(inode, ts: inode_set_ctime_current(inode));
67 }
68
69 bytes = count;
70
71out:
72 inode_unlock(inode);
73
74 kfree(objp: data);
75
76 return bytes;
77}
78
79static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
80 size_t count, loff_t *ppos)
81{
82 struct efivar_entry *var = file->private_data;
83 unsigned long datasize = 0;
84 u32 attributes;
85 void *data;
86 ssize_t size = 0;
87 int err;
88
89 while (!__ratelimit(&file->f_cred->user->ratelimit))
90 msleep(msecs: 50);
91
92 err = efivar_entry_size(entry: var, size: &datasize);
93
94 /*
95 * efivarfs represents uncommitted variables with
96 * zero-length files. Reading them should return EOF.
97 */
98 if (err == -ENOENT)
99 return 0;
100 else if (err)
101 return err;
102
103 data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
104
105 if (!data)
106 return -ENOMEM;
107
108 size = efivar_entry_get(entry: var, attributes: &attributes, size: &datasize,
109 data: data + sizeof(attributes));
110 if (size)
111 goto out_free;
112
113 memcpy(data, &attributes, sizeof(attributes));
114 size = simple_read_from_buffer(to: userbuf, count, ppos,
115 from: data, available: datasize + sizeof(attributes));
116out_free:
117 kfree(objp: data);
118
119 return size;
120}
121
122static int efivarfs_file_release(struct inode *inode, struct file *file)
123{
124 struct efivar_entry *var = inode->i_private;
125
126 inode_lock(inode);
127 var->removed = (--var->open_count == 0 && i_size_read(inode) == 0);
128 inode_unlock(inode);
129
130 if (var->removed)
131 simple_recursive_removal(file->f_path.dentry, NULL);
132
133 return 0;
134}
135
136static int efivarfs_file_open(struct inode *inode, struct file *file)
137{
138 struct efivar_entry *entry = inode->i_private;
139
140 file->private_data = entry;
141
142 inode_lock(inode);
143 entry->open_count++;
144 inode_unlock(inode);
145
146 return 0;
147}
148
149const struct file_operations efivarfs_file_operations = {
150 .open = efivarfs_file_open,
151 .read = efivarfs_file_read,
152 .write = efivarfs_file_write,
153 .release = efivarfs_file_release,
154};
155

source code of linux/fs/efivarfs/file.c