GNU Linux-libre 4.4.284-gnu1
[releases.git] / lib / test_firmware.c
1 /*
2  * This module provides an interface to trigger and test firmware loading.
3  *
4  * It is designed to be used for basic evaluation of the firmware loading
5  * subsystem (for example when validating firmware verification). It lacks
6  * any extra dependencies, and will not normally be loaded by the system
7  * unless explicitly requested by name.
8  */
9
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12 #include <linux/init.h>
13 #include <linux/module.h>
14 #include <linux/printk.h>
15 #include <linux/firmware.h>
16 #include <linux/device.h>
17 #include <linux/fs.h>
18 #include <linux/miscdevice.h>
19 #include <linux/slab.h>
20 #include <linux/uaccess.h>
21
22 static DEFINE_MUTEX(test_fw_mutex);
23 static const struct firmware *test_firmware;
24
25 static ssize_t test_fw_misc_read(struct file *f, char __user *buf,
26                                  size_t size, loff_t *offset)
27 {
28         ssize_t rc = 0;
29
30         mutex_lock(&test_fw_mutex);
31         if (test_firmware)
32                 rc = simple_read_from_buffer(buf, size, offset,
33                                              test_firmware->data,
34                                              test_firmware->size);
35         mutex_unlock(&test_fw_mutex);
36         return rc;
37 }
38
39 static const struct file_operations test_fw_fops = {
40         .owner          = THIS_MODULE,
41         .read           = test_fw_misc_read,
42 };
43
44 static struct miscdevice test_fw_misc_device = {
45         .minor          = MISC_DYNAMIC_MINOR,
46         .name           = "test_firmware",
47         .fops           = &test_fw_fops,
48 };
49
50 static ssize_t trigger_request_store(struct device *dev,
51                                      struct device_attribute *attr,
52                                      const char *buf, size_t count)
53 {
54         int rc;
55         char *name;
56
57         name = kzalloc(count + 1, GFP_KERNEL);
58         if (!name)
59                 return -ENOSPC;
60         memcpy(name, buf, count);
61
62         pr_info("loading '%s'\n", name);
63
64         mutex_lock(&test_fw_mutex);
65         release_firmware(test_firmware);
66         test_firmware = NULL;
67         rc = request_firmware(&test_firmware, name, dev);
68         if (rc) {
69                 pr_info("load of '%s' failed: %d\n", name, rc);
70                 goto out;
71         }
72         pr_info("loaded: %zu\n", test_firmware->size);
73         rc = count;
74
75 out:
76         mutex_unlock(&test_fw_mutex);
77
78         kfree(name);
79
80         return rc;
81 }
82 static DEVICE_ATTR_WO(trigger_request);
83
84 static int __init test_firmware_init(void)
85 {
86         int rc;
87
88         rc = misc_register(&test_fw_misc_device);
89         if (rc) {
90                 pr_err("could not register misc device: %d\n", rc);
91                 return rc;
92         }
93         rc = device_create_file(test_fw_misc_device.this_device,
94                                 &dev_attr_trigger_request);
95         if (rc) {
96                 pr_err("could not create sysfs interface: %d\n", rc);
97                 goto dereg;
98         }
99
100         pr_warn("interface ready\n");
101
102         return 0;
103 dereg:
104         misc_deregister(&test_fw_misc_device);
105         return rc;
106 }
107
108 module_init(test_firmware_init);
109
110 static void __exit test_firmware_exit(void)
111 {
112         release_firmware(test_firmware);
113         device_remove_file(test_fw_misc_device.this_device,
114                            &dev_attr_trigger_request);
115         misc_deregister(&test_fw_misc_device);
116         pr_warn("removed interface\n");
117 }
118
119 module_exit(test_firmware_exit);
120
121 MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
122 MODULE_LICENSE("GPL");