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(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(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(&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(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 list_add(&fw_priv->pending_list, &pending_fw_head); 99 mutex_unlock(&fw_lock); 100 101 if (fw_priv->opt_flags & FW_OPT_UEVENT) { 102 fw_priv->need_uevent = true; 103 dev_set_uevent_suppress(f_dev, false); 104 dev_dbg(f_dev, "firmware: requesting %s\n", fw_priv->fw_name); 105 kobject_uevent(&fw_sysfs->dev.kobj, 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(&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(f_dev); 125 err_put_dev: 126 put_device(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, name, device, opt_flags); 156 if (IS_ERR(fw_sysfs)) { 157 ret = PTR_ERR(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(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(LOADING_FIRMWARE, 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(fw, name, device, opt_flags); 239 } 240