projects/linux·blob master · refs

249 lines · 6.6 KiB

1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/types.h>
4#include <linux/kconfig.h>
5#include <linux/list.h>
6#include <linux/security.h>
7#include <linux/umh.h>
8#include <linux/sysctl.h>
9#include <linux/module.h>
10
11#include "fallback.h"
12#include "firmware.h"
13
14/*
15 * firmware fallback mechanism
16 */
17
18/*
19 * use small loading timeout for caching devices' firmware because all these
20 * firmware images have been loaded successfully at lease once, also system is
21 * ready for completing firmware loading now. The maximum size of firmware in
22 * current distributions is about 2M bytes, so 10 secs should be enough.
23 */
24void fw_fallback_set_cache_timeout(void)
25{
26 fw_fallback_config.old_timeout = __firmware_loading_timeout();
27 __fw_fallback_set_timeout(10);
28}
29
30/* Restores the timeout to the value last configured during normal operation */
31void fw_fallback_set_default_timeout(void)
32{
33 __fw_fallback_set_timeout(fw_fallback_config.old_timeout);
34}
35
36static long firmware_loading_timeout(void)
37{
38 return __firmware_loading_timeout() > 0 ?
39 __firmware_loading_timeout() * HZ : MAX_JIFFY_OFFSET;
40}
41
42static inline int fw_sysfs_wait_timeout(struct fw_priv *fw_priv, long timeout)
43{
44 return __fw_state_wait_common(fw_priv, timeout);
45}
46
47static LIST_HEAD(pending_fw_head);
48
49void kill_pending_fw_fallback_reqs(bool kill_all)
50{
51 struct fw_priv *fw_priv;
52 struct fw_priv *next;
53
54 mutex_lock(&fw_lock);
55 list_for_each_entry_safe(fw_priv, next, &pending_fw_head,
56 pending_list) {
57 if (kill_all || !fw_priv->need_uevent)
58 __fw_load_abort(fw_priv);
59 }
60
61 if (kill_all)
62 fw_load_abort_all = true;
63
64 mutex_unlock(&fw_lock);
65}
66
67/**
68 * fw_load_sysfs_fallback() - load a firmware via the sysfs fallback mechanism
69 * @fw_sysfs: firmware sysfs information for the firmware to load
70 * @timeout: timeout to wait for the load
71 *
72 * In charge of constructing a sysfs fallback interface for firmware loading.
73 **/
74static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs, long timeout)
75{
76 int retval = 0;
77 struct device *f_dev = &fw_sysfs->dev;
78 struct fw_priv *fw_priv = fw_sysfs->fw_priv;
79
80 /* fall back on userspace loading */
81 if (!fw_priv->data)
82 fw_priv->is_paged_buf = true;
83
84 dev_set_uevent_suppress(f_dev, true);
85
86 retval = device_add(f_dev);
87 if (retval) {
88 dev_err(f_dev, "%s: device_register failed\n", __func__);
89 goto err_put_dev;
90 }
91
92 mutex_lock(&fw_lock);
93 if (fw_load_abort_all || fw_state_is_aborted(fw_priv)) {
94 mutex_unlock(&fw_lock);
95 retval = -EINTR;
96 goto out;
97 }
98
99 /*
100 * device_add() exposes the loading interface before pending_list is
101 * linked into pending_fw_head, so fw_state_done() may run first.
102 */
103 if (fw_state_is_done(fw_priv)) {
104 mutex_unlock(&fw_lock);
105 goto out;
106 }
107
108 list_add(&fw_priv->pending_list, &pending_fw_head);
109 mutex_unlock(&fw_lock);
110
111 if (fw_priv->opt_flags & FW_OPT_UEVENT) {
112 fw_priv->need_uevent = true;
113 dev_set_uevent_suppress(f_dev, false);
114 dev_dbg(f_dev, "firmware: requesting %s\n", fw_priv->fw_name);
115 kobject_uevent(&fw_sysfs->dev.kobj, KOBJ_ADD);
116 } else {
117 timeout = MAX_JIFFY_OFFSET;
118 }
119
120 retval = fw_sysfs_wait_timeout(fw_priv, timeout);
121 if (retval < 0 && retval != -ENOENT) {
122 mutex_lock(&fw_lock);
123 fw_load_abort(fw_sysfs);
124 mutex_unlock(&fw_lock);
125 }
126
127 if (fw_state_is_aborted(fw_priv)) {
128 if (retval == -ERESTARTSYS)
129 retval = -EINTR;
130 } else if (fw_priv->is_paged_buf && !fw_priv->data)
131 retval = -ENOMEM;
132
133out:
134 device_del(f_dev);
135err_put_dev:
136 put_device(f_dev);
137 return retval;
138}
139
140static int fw_load_from_user_helper(struct firmware *firmware,
141 const char *name, struct device *device,
142 u32 opt_flags)
143{
144 struct fw_sysfs *fw_sysfs;
145 long timeout;
146 int ret;
147
148 timeout = firmware_loading_timeout();
149 if (opt_flags & FW_OPT_NOWAIT) {
150 timeout = usermodehelper_read_lock_wait(timeout);
151 if (!timeout) {
152 dev_dbg(device, "firmware: %s loading timed out\n",
153 name);
154 return -EBUSY;
155 }
156 } else {
157 ret = usermodehelper_read_trylock();
158 if (WARN_ON(ret)) {
159 dev_err(device, "firmware: %s will not be loaded\n",
160 name);
161 return ret;
162 }
163 }
164
165 fw_sysfs = fw_create_instance(firmware, name, device, opt_flags);
166 if (IS_ERR(fw_sysfs)) {
167 ret = PTR_ERR(fw_sysfs);
168 goto out_unlock;
169 }
170
171 fw_sysfs->fw_priv = firmware->priv;
172 ret = fw_load_sysfs_fallback(fw_sysfs, timeout);
173
174 if (!ret)
175 ret = assign_fw(firmware, device);
176
177out_unlock:
178 usermodehelper_read_unlock();
179
180 return ret;
181}
182
183static bool fw_force_sysfs_fallback(u32 opt_flags)
184{
185 if (fw_fallback_config.force_sysfs_fallback)
186 return true;
187 if (!(opt_flags & FW_OPT_USERHELPER))
188 return false;
189 return true;
190}
191
192static bool fw_run_sysfs_fallback(u32 opt_flags)
193{
194 int ret;
195
196 if (fw_fallback_config.ignore_sysfs_fallback) {
197 pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n");
198 return false;
199 }
200
201 if ((opt_flags & FW_OPT_NOFALLBACK_SYSFS))
202 return false;
203
204 /* Also permit LSMs and IMA to fail firmware sysfs fallback */
205 ret = security_kernel_load_data(LOADING_FIRMWARE, true);
206 if (ret < 0)
207 return false;
208
209 return fw_force_sysfs_fallback(opt_flags);
210}
211
212/**
213 * firmware_fallback_sysfs() - use the fallback mechanism to find firmware
214 * @fw: pointer to firmware image
215 * @name: name of firmware file to look for
216 * @device: device for which firmware is being loaded
217 * @opt_flags: options to control firmware loading behaviour, as defined by
218 * &enum fw_opt
219 * @ret: return value from direct lookup which triggered the fallback mechanism
220 *
221 * This function is called if direct lookup for the firmware failed, it enables
222 * a fallback mechanism through userspace by exposing a sysfs loading
223 * interface. Userspace is in charge of loading the firmware through the sysfs
224 * loading interface. This sysfs fallback mechanism may be disabled completely
225 * on a system by setting the proc sysctl value ignore_sysfs_fallback to true.
226 * If this is false we check if the internal API caller set the
227 * @FW_OPT_NOFALLBACK_SYSFS flag, if so it would also disable the fallback
228 * mechanism. A system may want to enforce the sysfs fallback mechanism at all
229 * times, it can do this by setting ignore_sysfs_fallback to false and
230 * force_sysfs_fallback to true.
231 * Enabling force_sysfs_fallback is functionally equivalent to build a kernel
232 * with CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
233 **/
234int firmware_fallback_sysfs(struct firmware *fw, const char *name,
235 struct device *device,
236 u32 opt_flags,
237 int ret)
238{
239 if (!fw_run_sysfs_fallback(opt_flags))
240 return ret;
241
242 if (!(opt_flags & FW_OPT_NO_WARN))
243 dev_warn(device, "Falling back to sysfs fallback for: %s\n",
244 name);
245 else
246 dev_dbg(device, "Falling back to sysfs fallback for: %s\n",
247 name);
248 return fw_load_from_user_helper(fw, name, device, opt_flags);
249}