projects/linux·blob v4.6 · refs

186 lines · 4.3 KiB

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/completion.h>
16#include <linux/firmware.h>
17#include <linux/device.h>
18#include <linux/fs.h>
19#include <linux/miscdevice.h>
20#include <linux/slab.h>
21#include <linux/uaccess.h>
22
23static DEFINE_MUTEX(test_fw_mutex);
24static const struct firmware *test_firmware;
25
26static ssize_t test_fw_misc_read(struct file *f, char __user *buf,
27 size_t size, loff_t *offset)
28{
29 ssize_t rc = 0;
30
31 mutex_lock(&test_fw_mutex);
32 if (test_firmware)
33 rc = simple_read_from_buffer(buf, size, offset,
34 test_firmware->data,
35 test_firmware->size);
36 mutex_unlock(&test_fw_mutex);
37 return rc;
38}
39
40static const struct file_operations test_fw_fops = {
41 .owner = THIS_MODULE,
42 .read = test_fw_misc_read,
43};
44
45static struct miscdevice test_fw_misc_device = {
46 .minor = MISC_DYNAMIC_MINOR,
47 .name = "test_firmware",
48 .fops = &test_fw_fops,
49};
50
51static ssize_t trigger_request_store(struct device *dev,
52 struct device_attribute *attr,
53 const char *buf, size_t count)
54{
55 int rc;
56 char *name;
57
58 name = kstrndup(buf, count, GFP_KERNEL);
59 if (!name)
60 return -ENOSPC;
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
75out:
76 mutex_unlock(&test_fw_mutex);
77
78 kfree(name);
79
80 return rc;
81}
82static DEVICE_ATTR_WO(trigger_request);
83
84static DECLARE_COMPLETION(async_fw_done);
85
86static void trigger_async_request_cb(const struct firmware *fw, void *context)
87{
88 test_firmware = fw;
89 complete(&async_fw_done);
90}
91
92static ssize_t trigger_async_request_store(struct device *dev,
93 struct device_attribute *attr,
94 const char *buf, size_t count)
95{
96 int rc;
97 char *name;
98
99 name = kstrndup(buf, count, GFP_KERNEL);
100 if (!name)
101 return -ENOSPC;
102
103 pr_info("loading '%s'\n", name);
104
105 mutex_lock(&test_fw_mutex);
106 release_firmware(test_firmware);
107 test_firmware = NULL;
108 rc = request_firmware_nowait(THIS_MODULE, 1, name, dev, GFP_KERNEL,
109 NULL, trigger_async_request_cb);
110 if (rc) {
111 pr_info("async load of '%s' failed: %d\n", name, rc);
112 kfree(name);
113 goto out;
114 }
115 /* Free 'name' ASAP, to test for race conditions */
116 kfree(name);
117
118 wait_for_completion(&async_fw_done);
119
120 if (test_firmware) {
121 pr_info("loaded: %zu\n", test_firmware->size);
122 rc = count;
123 } else {
124 pr_err("failed to async load firmware\n");
125 rc = -ENODEV;
126 }
127
128out:
129 mutex_unlock(&test_fw_mutex);
130
131 return rc;
132}
133static DEVICE_ATTR_WO(trigger_async_request);
134
135static int __init test_firmware_init(void)
136{
137 int rc;
138
139 rc = misc_register(&test_fw_misc_device);
140 if (rc) {
141 pr_err("could not register misc device: %d\n", rc);
142 return rc;
143 }
144 rc = device_create_file(test_fw_misc_device.this_device,
145 &dev_attr_trigger_request);
146 if (rc) {
147 pr_err("could not create sysfs interface: %d\n", rc);
148 goto dereg;
149 }
150
151 rc = device_create_file(test_fw_misc_device.this_device,
152 &dev_attr_trigger_async_request);
153 if (rc) {
154 pr_err("could not create async sysfs interface: %d\n", rc);
155 goto remove_file;
156 }
157
158 pr_warn("interface ready\n");
159
160 return 0;
161
162remove_file:
163 device_remove_file(test_fw_misc_device.this_device,
164 &dev_attr_trigger_async_request);
165dereg:
166 misc_deregister(&test_fw_misc_device);
167 return rc;
168}
169
170module_init(test_firmware_init);
171
172static void __exit test_firmware_exit(void)
173{
174 release_firmware(test_firmware);
175 device_remove_file(test_fw_misc_device.this_device,
176 &dev_attr_trigger_async_request);
177 device_remove_file(test_fw_misc_device.this_device,
178 &dev_attr_trigger_request);
179 misc_deregister(&test_fw_misc_device);
180 pr_warn("removed interface\n");
181}
182
183module_exit(test_firmware_exit);
184
185MODULE_AUTHOR("Kees Cook <[email protected]>");
186MODULE_LICENSE("GPL");