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
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 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
60 out:
61 kfree(data);
62
63 return bytes;
64 }
65
66 static 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));
103 out_free:
104 kfree(data);
105
106 return size;
107 }
108
109 const 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
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