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
efivarfs_file_write(struct file * file,const char __user * userbuf,size_t count,loff_t * ppos)15 static 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 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(var, attributes, &datasize,
51 data, &set);
52 if (!set) {
53 if (bytes == -ENOENT)
54 bytes = -EIO;
55 goto out;
56 }
57
58 if (bytes == -ENOENT) {
59 /*
60 * FIXME: temporary workaround for fwupdate, signal
61 * failed write with a 1 to keep created but not
62 * written files
63 */
64 i_size_write(inode, 1);
65 } else {
66 i_size_write(inode, datasize + sizeof(attributes));
67 inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
68 }
69
70 bytes = count;
71
72 out:
73 inode_unlock(inode);
74
75 kfree(data);
76
77 return bytes;
78 }
79
efivarfs_file_read(struct file * file,char __user * userbuf,size_t count,loff_t * ppos)80 static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
81 size_t count, loff_t *ppos)
82 {
83 struct efivar_entry *var = file->private_data;
84 unsigned long datasize = 0;
85 u32 attributes;
86 void *data;
87 ssize_t size = 0;
88 int err;
89
90 while (!__ratelimit(&file->f_cred->user->ratelimit))
91 msleep(50);
92
93 err = efivar_entry_size(var, &datasize);
94
95 /*
96 * efivarfs represents uncommitted variables with
97 * zero-length files. Reading them should return EOF.
98 */
99 if (err == -ENOENT)
100 return 0;
101 else if (err)
102 return err;
103
104 data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
105
106 if (!data)
107 return -ENOMEM;
108
109 size = efivar_entry_get(var, &attributes, &datasize,
110 data + sizeof(attributes));
111 if (size)
112 goto out_free;
113
114 memcpy(data, &attributes, sizeof(attributes));
115 size = simple_read_from_buffer(userbuf, count, ppos,
116 data, datasize + sizeof(attributes));
117 out_free:
118 kfree(data);
119
120 return size;
121 }
122
efivarfs_file_release(struct inode * inode,struct file * file)123 static int efivarfs_file_release(struct inode *inode, struct file *file)
124 {
125 struct efivar_entry *var = inode->i_private;
126
127 inode_lock(inode);
128 /* FIXME: temporary work around for fwupdate */
129 var->removed = (--var->open_count == 0 && i_size_read(inode) == 1);
130 inode_unlock(inode);
131
132 if (var->removed)
133 simple_recursive_removal(file->f_path.dentry, NULL);
134
135 return 0;
136 }
137
efivarfs_file_open(struct inode * inode,struct file * file)138 static int efivarfs_file_open(struct inode *inode, struct file *file)
139 {
140 struct efivar_entry *entry = inode->i_private;
141
142 file->private_data = entry;
143
144 inode_lock(inode);
145 entry->open_count++;
146 inode_unlock(inode);
147
148 return 0;
149 }
150
151 const struct file_operations efivarfs_file_operations = {
152 .open = efivarfs_file_open,
153 .read = efivarfs_file_read,
154 .write = efivarfs_file_write,
155 .release = efivarfs_file_release,
156 };
157