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 | */ |
24 | void fw_fallback_set_cache_timeout(void) |
25 | { |
26 | fw_fallback_config.old_timeout = __firmware_loading_timeout(); |
27 | __fw_fallback_set_timeout(timeout: 10); |
28 | } |
29 | |
30 | /* Restores the timeout to the value last configured during normal operation */ |
31 | void fw_fallback_set_default_timeout(void) |
32 | { |
33 | __fw_fallback_set_timeout(timeout: fw_fallback_config.old_timeout); |
34 | } |
35 | |
36 | static long firmware_loading_timeout(void) |
37 | { |
38 | return __firmware_loading_timeout() > 0 ? |
39 | __firmware_loading_timeout() * HZ : MAX_JIFFY_OFFSET; |
40 | } |
41 | |
42 | static 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 | |
47 | static LIST_HEAD(pending_fw_head); |
48 | |
49 | void 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(lock: &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 | **/ |
74 | static 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(dev: f_dev, val: true); |
85 | |
86 | retval = device_add(dev: 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(lock: &fw_lock); |
95 | retval = -EINTR; |
96 | goto out; |
97 | } |
98 | list_add(new: &fw_priv->pending_list, head: &pending_fw_head); |
99 | mutex_unlock(lock: &fw_lock); |
100 | |
101 | if (fw_priv->opt_flags & FW_OPT_UEVENT) { |
102 | fw_priv->need_uevent = true; |
103 | dev_set_uevent_suppress(dev: f_dev, val: false); |
104 | dev_dbg(f_dev, "firmware: requesting %s\n" , fw_priv->fw_name); |
105 | kobject_uevent(kobj: &fw_sysfs->dev.kobj, action: KOBJ_ADD); |
106 | } else { |
107 | timeout = MAX_JIFFY_OFFSET; |
108 | } |
109 | |
110 | retval = fw_sysfs_wait_timeout(fw_priv, timeout); |
111 | if (retval < 0 && retval != -ENOENT) { |
112 | mutex_lock(&fw_lock); |
113 | fw_load_abort(fw_sysfs); |
114 | mutex_unlock(lock: &fw_lock); |
115 | } |
116 | |
117 | if (fw_state_is_aborted(fw_priv)) { |
118 | if (retval == -ERESTARTSYS) |
119 | retval = -EINTR; |
120 | } else if (fw_priv->is_paged_buf && !fw_priv->data) |
121 | retval = -ENOMEM; |
122 | |
123 | out: |
124 | device_del(dev: f_dev); |
125 | err_put_dev: |
126 | put_device(dev: f_dev); |
127 | return retval; |
128 | } |
129 | |
130 | static int fw_load_from_user_helper(struct firmware *firmware, |
131 | const char *name, struct device *device, |
132 | u32 opt_flags) |
133 | { |
134 | struct fw_sysfs *fw_sysfs; |
135 | long timeout; |
136 | int ret; |
137 | |
138 | timeout = firmware_loading_timeout(); |
139 | if (opt_flags & FW_OPT_NOWAIT) { |
140 | timeout = usermodehelper_read_lock_wait(timeout); |
141 | if (!timeout) { |
142 | dev_dbg(device, "firmware: %s loading timed out\n" , |
143 | name); |
144 | return -EBUSY; |
145 | } |
146 | } else { |
147 | ret = usermodehelper_read_trylock(); |
148 | if (WARN_ON(ret)) { |
149 | dev_err(device, "firmware: %s will not be loaded\n" , |
150 | name); |
151 | return ret; |
152 | } |
153 | } |
154 | |
155 | fw_sysfs = fw_create_instance(firmware, fw_name: name, device, opt_flags); |
156 | if (IS_ERR(ptr: fw_sysfs)) { |
157 | ret = PTR_ERR(ptr: fw_sysfs); |
158 | goto out_unlock; |
159 | } |
160 | |
161 | fw_sysfs->fw_priv = firmware->priv; |
162 | ret = fw_load_sysfs_fallback(fw_sysfs, timeout); |
163 | |
164 | if (!ret) |
165 | ret = assign_fw(fw: firmware, device); |
166 | |
167 | out_unlock: |
168 | usermodehelper_read_unlock(); |
169 | |
170 | return ret; |
171 | } |
172 | |
173 | static bool fw_force_sysfs_fallback(u32 opt_flags) |
174 | { |
175 | if (fw_fallback_config.force_sysfs_fallback) |
176 | return true; |
177 | if (!(opt_flags & FW_OPT_USERHELPER)) |
178 | return false; |
179 | return true; |
180 | } |
181 | |
182 | static bool fw_run_sysfs_fallback(u32 opt_flags) |
183 | { |
184 | int ret; |
185 | |
186 | if (fw_fallback_config.ignore_sysfs_fallback) { |
187 | pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n" ); |
188 | return false; |
189 | } |
190 | |
191 | if ((opt_flags & FW_OPT_NOFALLBACK_SYSFS)) |
192 | return false; |
193 | |
194 | /* Also permit LSMs and IMA to fail firmware sysfs fallback */ |
195 | ret = security_kernel_load_data(id: LOADING_FIRMWARE, contents: true); |
196 | if (ret < 0) |
197 | return false; |
198 | |
199 | return fw_force_sysfs_fallback(opt_flags); |
200 | } |
201 | |
202 | /** |
203 | * firmware_fallback_sysfs() - use the fallback mechanism to find firmware |
204 | * @fw: pointer to firmware image |
205 | * @name: name of firmware file to look for |
206 | * @device: device for which firmware is being loaded |
207 | * @opt_flags: options to control firmware loading behaviour, as defined by |
208 | * &enum fw_opt |
209 | * @ret: return value from direct lookup which triggered the fallback mechanism |
210 | * |
211 | * This function is called if direct lookup for the firmware failed, it enables |
212 | * a fallback mechanism through userspace by exposing a sysfs loading |
213 | * interface. Userspace is in charge of loading the firmware through the sysfs |
214 | * loading interface. This sysfs fallback mechanism may be disabled completely |
215 | * on a system by setting the proc sysctl value ignore_sysfs_fallback to true. |
216 | * If this is false we check if the internal API caller set the |
217 | * @FW_OPT_NOFALLBACK_SYSFS flag, if so it would also disable the fallback |
218 | * mechanism. A system may want to enforce the sysfs fallback mechanism at all |
219 | * times, it can do this by setting ignore_sysfs_fallback to false and |
220 | * force_sysfs_fallback to true. |
221 | * Enabling force_sysfs_fallback is functionally equivalent to build a kernel |
222 | * with CONFIG_FW_LOADER_USER_HELPER_FALLBACK. |
223 | **/ |
224 | int firmware_fallback_sysfs(struct firmware *fw, const char *name, |
225 | struct device *device, |
226 | u32 opt_flags, |
227 | int ret) |
228 | { |
229 | if (!fw_run_sysfs_fallback(opt_flags)) |
230 | return ret; |
231 | |
232 | if (!(opt_flags & FW_OPT_NO_WARN)) |
233 | dev_warn(device, "Falling back to sysfs fallback for: %s\n" , |
234 | name); |
235 | else |
236 | dev_dbg(device, "Falling back to sysfs fallback for: %s\n" , |
237 | name); |
238 | return fw_load_from_user_helper(firmware: fw, name, device, opt_flags); |
239 | } |
240 | |