1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * umh - the kernel usermode helper 3 * umh - the kernel usermode helper
4 */ 4 */
5 #include <linux/module.h> 5 #include <linux/module.h>
6 #include <linux/sched.h> 6 #include <linux/sched.h>
7 #include <linux/sched/task.h> 7 #include <linux/sched/task.h>
8 #include <linux/binfmts.h> 8 #include <linux/binfmts.h>
9 #include <linux/syscalls.h> 9 #include <linux/syscalls.h>
10 #include <linux/unistd.h> 10 #include <linux/unistd.h>
11 #include <linux/kmod.h> 11 #include <linux/kmod.h>
12 #include <linux/slab.h> 12 #include <linux/slab.h>
13 #include <linux/completion.h> 13 #include <linux/completion.h>
14 #include <linux/cred.h> 14 #include <linux/cred.h>
15 #include <linux/file.h> 15 #include <linux/file.h>
16 #include <linux/fdtable.h> 16 #include <linux/fdtable.h>
17 #include <linux/fs_struct.h> 17 #include <linux/fs_struct.h>
18 #include <linux/workqueue.h> 18 #include <linux/workqueue.h>
19 #include <linux/security.h> 19 #include <linux/security.h>
20 #include <linux/mount.h> 20 #include <linux/mount.h>
21 #include <linux/kernel.h> 21 #include <linux/kernel.h>
22 #include <linux/init.h> 22 #include <linux/init.h>
23 #include <linux/resource.h> 23 #include <linux/resource.h>
24 #include <linux/notifier.h> 24 #include <linux/notifier.h>
25 #include <linux/suspend.h> 25 #include <linux/suspend.h>
26 #include <linux/rwsem.h> 26 #include <linux/rwsem.h>
27 #include <linux/ptrace.h> 27 #include <linux/ptrace.h>
28 #include <linux/async.h> 28 #include <linux/async.h>
29 #include <linux/uaccess.h> 29 #include <linux/uaccess.h>
30 #include <linux/initrd.h> 30 #include <linux/initrd.h>
31 #include <linux/freezer.h> <<
32 31
33 #include <trace/events/module.h> 32 #include <trace/events/module.h>
34 33
>> 34 #define CAP_BSET (void *)1
>> 35 #define CAP_PI (void *)2
>> 36
35 static kernel_cap_t usermodehelper_bset = CAP_ 37 static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
36 static kernel_cap_t usermodehelper_inheritable 38 static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
37 static DEFINE_SPINLOCK(umh_sysctl_lock); 39 static DEFINE_SPINLOCK(umh_sysctl_lock);
38 static DECLARE_RWSEM(umhelper_sem); 40 static DECLARE_RWSEM(umhelper_sem);
39 41
40 static void call_usermodehelper_freeinfo(struc 42 static void call_usermodehelper_freeinfo(struct subprocess_info *info)
41 { 43 {
42 if (info->cleanup) 44 if (info->cleanup)
43 (*info->cleanup)(info); 45 (*info->cleanup)(info);
44 kfree(info); 46 kfree(info);
45 } 47 }
46 48
47 static void umh_complete(struct subprocess_inf 49 static void umh_complete(struct subprocess_info *sub_info)
48 { 50 {
49 struct completion *comp = xchg(&sub_in 51 struct completion *comp = xchg(&sub_info->complete, NULL);
50 /* 52 /*
51 * See call_usermodehelper_exec(). If 53 * See call_usermodehelper_exec(). If xchg() returns NULL
52 * we own sub_info, the UMH_KILLABLE c 54 * we own sub_info, the UMH_KILLABLE caller has gone away
53 * or the caller used UMH_NO_WAIT. 55 * or the caller used UMH_NO_WAIT.
54 */ 56 */
55 if (comp) 57 if (comp)
56 complete(comp); 58 complete(comp);
57 else 59 else
58 call_usermodehelper_freeinfo(s 60 call_usermodehelper_freeinfo(sub_info);
59 } 61 }
60 62
61 /* 63 /*
62 * This is the task which runs the usermode ap 64 * This is the task which runs the usermode application
63 */ 65 */
64 static int call_usermodehelper_exec_async(void 66 static int call_usermodehelper_exec_async(void *data)
65 { 67 {
66 struct subprocess_info *sub_info = dat 68 struct subprocess_info *sub_info = data;
67 struct cred *new; 69 struct cred *new;
68 int retval; 70 int retval;
69 71
70 spin_lock_irq(¤t->sighand->siglo 72 spin_lock_irq(¤t->sighand->siglock);
71 flush_signal_handlers(current, 1); 73 flush_signal_handlers(current, 1);
72 spin_unlock_irq(¤t->sighand->sig 74 spin_unlock_irq(¤t->sighand->siglock);
73 75
74 /* 76 /*
75 * Initial kernel threads share ther F 77 * Initial kernel threads share ther FS with init, in order to
76 * get the init root directory. But we 78 * get the init root directory. But we've now created a new
77 * thread that is going to execve a us 79 * thread that is going to execve a user process and has its own
78 * 'struct fs_struct'. Reset umask to 80 * 'struct fs_struct'. Reset umask to the default.
79 */ 81 */
80 current->fs->umask = 0022; 82 current->fs->umask = 0022;
81 83
82 /* 84 /*
83 * Our parent (unbound workqueue) runs 85 * Our parent (unbound workqueue) runs with elevated scheduling
84 * priority. Avoid propagating that in 86 * priority. Avoid propagating that into the userspace child.
85 */ 87 */
86 set_user_nice(current, 0); 88 set_user_nice(current, 0);
87 89
88 retval = -ENOMEM; 90 retval = -ENOMEM;
89 new = prepare_kernel_cred(current); 91 new = prepare_kernel_cred(current);
90 if (!new) 92 if (!new)
91 goto out; 93 goto out;
92 94
93 spin_lock(&umh_sysctl_lock); 95 spin_lock(&umh_sysctl_lock);
94 new->cap_bset = cap_intersect(usermode 96 new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
95 new->cap_inheritable = cap_intersect(u 97 new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
96 n 98 new->cap_inheritable);
97 spin_unlock(&umh_sysctl_lock); 99 spin_unlock(&umh_sysctl_lock);
98 100
99 if (sub_info->init) { 101 if (sub_info->init) {
100 retval = sub_info->init(sub_in 102 retval = sub_info->init(sub_info, new);
101 if (retval) { 103 if (retval) {
102 abort_creds(new); 104 abort_creds(new);
103 goto out; 105 goto out;
104 } 106 }
105 } 107 }
106 108
107 commit_creds(new); 109 commit_creds(new);
108 110
109 wait_for_initramfs(); 111 wait_for_initramfs();
110 retval = kernel_execve(sub_info->path, 112 retval = kernel_execve(sub_info->path,
111 (const char *co 113 (const char *const *)sub_info->argv,
112 (const char *co 114 (const char *const *)sub_info->envp);
113 out: 115 out:
114 sub_info->retval = retval; 116 sub_info->retval = retval;
115 /* 117 /*
116 * call_usermodehelper_exec_sync() wil 118 * call_usermodehelper_exec_sync() will call umh_complete
117 * if UHM_WAIT_PROC. 119 * if UHM_WAIT_PROC.
118 */ 120 */
119 if (!(sub_info->wait & UMH_WAIT_PROC)) 121 if (!(sub_info->wait & UMH_WAIT_PROC))
120 umh_complete(sub_info); 122 umh_complete(sub_info);
121 if (!retval) 123 if (!retval)
122 return 0; 124 return 0;
123 do_exit(0); 125 do_exit(0);
124 } 126 }
125 127
126 /* Handles UMH_WAIT_PROC. */ 128 /* Handles UMH_WAIT_PROC. */
127 static void call_usermodehelper_exec_sync(stru 129 static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
128 { 130 {
129 pid_t pid; 131 pid_t pid;
130 132
131 /* If SIGCLD is ignored do_wait won't 133 /* If SIGCLD is ignored do_wait won't populate the status. */
132 kernel_sigaction(SIGCHLD, SIG_DFL); 134 kernel_sigaction(SIGCHLD, SIG_DFL);
133 pid = user_mode_thread(call_usermodehe !! 135 pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
134 if (pid < 0) 136 if (pid < 0)
135 sub_info->retval = pid; 137 sub_info->retval = pid;
136 else 138 else
137 kernel_wait(pid, &sub_info->re 139 kernel_wait(pid, &sub_info->retval);
138 140
139 /* Restore default kernel sig handler 141 /* Restore default kernel sig handler */
140 kernel_sigaction(SIGCHLD, SIG_IGN); 142 kernel_sigaction(SIGCHLD, SIG_IGN);
141 umh_complete(sub_info); 143 umh_complete(sub_info);
142 } 144 }
143 145
144 /* 146 /*
145 * We need to create the usermodehelper kernel 147 * We need to create the usermodehelper kernel thread from a task that is affine
146 * to an optimized set of CPUs (or nohz housek 148 * to an optimized set of CPUs (or nohz housekeeping ones) such that they
147 * inherit a widest affinity irrespective of c 149 * inherit a widest affinity irrespective of call_usermodehelper() callers with
148 * possibly reduced affinity (eg: per-cpu work 150 * possibly reduced affinity (eg: per-cpu workqueues). We don't want
149 * usermodehelper targets to contend a busy CP 151 * usermodehelper targets to contend a busy CPU.
150 * 152 *
151 * Unbound workqueues provide such wide affini 153 * Unbound workqueues provide such wide affinity and allow to block on
152 * UMH_WAIT_PROC requests without blocking pen 154 * UMH_WAIT_PROC requests without blocking pending request (up to some limit).
153 * 155 *
154 * Besides, workqueues provide the privilege l 156 * Besides, workqueues provide the privilege level that caller might not have
155 * to perform the usermodehelper request. 157 * to perform the usermodehelper request.
156 * 158 *
157 */ 159 */
158 static void call_usermodehelper_exec_work(stru 160 static void call_usermodehelper_exec_work(struct work_struct *work)
159 { 161 {
160 struct subprocess_info *sub_info = 162 struct subprocess_info *sub_info =
161 container_of(work, struct subp 163 container_of(work, struct subprocess_info, work);
162 164
163 if (sub_info->wait & UMH_WAIT_PROC) { 165 if (sub_info->wait & UMH_WAIT_PROC) {
164 call_usermodehelper_exec_sync( 166 call_usermodehelper_exec_sync(sub_info);
165 } else { 167 } else {
166 pid_t pid; 168 pid_t pid;
167 /* 169 /*
168 * Use CLONE_PARENT to reparen 170 * Use CLONE_PARENT to reparent it to kthreadd; we do not
169 * want to pollute current->ch 171 * want to pollute current->children, and we need a parent
170 * that always ignores SIGCHLD 172 * that always ignores SIGCHLD to ensure auto-reaping.
171 */ 173 */
172 pid = user_mode_thread(call_us !! 174 pid = kernel_thread(call_usermodehelper_exec_async, sub_info,
173 CLONE_P !! 175 CLONE_PARENT | SIGCHLD);
174 if (pid < 0) { 176 if (pid < 0) {
175 sub_info->retval = pid 177 sub_info->retval = pid;
176 umh_complete(sub_info) 178 umh_complete(sub_info);
177 } 179 }
178 } 180 }
179 } 181 }
180 182
181 /* 183 /*
182 * If set, call_usermodehelper_exec() will exi 184 * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
183 * (used for preventing user land processes fr 185 * (used for preventing user land processes from being created after the user
184 * land has been frozen during a system-wide h 186 * land has been frozen during a system-wide hibernation or suspend operation).
185 * Should always be manipulated under umhelper 187 * Should always be manipulated under umhelper_sem acquired for write.
186 */ 188 */
187 static enum umh_disable_depth usermodehelper_d 189 static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
188 190
189 /* Number of helpers running */ 191 /* Number of helpers running */
190 static atomic_t running_helpers = ATOMIC_INIT( 192 static atomic_t running_helpers = ATOMIC_INIT(0);
191 193
192 /* 194 /*
193 * Wait queue head used by usermodehelper_disa 195 * Wait queue head used by usermodehelper_disable() to wait for all running
194 * helpers to finish. 196 * helpers to finish.
195 */ 197 */
196 static DECLARE_WAIT_QUEUE_HEAD(running_helpers 198 static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
197 199
198 /* 200 /*
199 * Used by usermodehelper_read_lock_wait() to 201 * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
200 * to become 'false'. 202 * to become 'false'.
201 */ 203 */
202 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_ 204 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
203 205
204 /* 206 /*
205 * Time to wait for running_helpers to become 207 * Time to wait for running_helpers to become zero before the setting of
206 * usermodehelper_disabled in usermodehelper_d 208 * usermodehelper_disabled in usermodehelper_disable() fails
207 */ 209 */
208 #define RUNNING_HELPERS_TIMEOUT (5 * HZ) 210 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
209 211
210 int usermodehelper_read_trylock(void) 212 int usermodehelper_read_trylock(void)
211 { 213 {
212 DEFINE_WAIT(wait); 214 DEFINE_WAIT(wait);
213 int ret = 0; 215 int ret = 0;
214 216
215 down_read(&umhelper_sem); 217 down_read(&umhelper_sem);
216 for (;;) { 218 for (;;) {
217 prepare_to_wait(&usermodehelpe 219 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
218 TASK_INTERRUPT 220 TASK_INTERRUPTIBLE);
219 if (!usermodehelper_disabled) 221 if (!usermodehelper_disabled)
220 break; 222 break;
221 223
222 if (usermodehelper_disabled == 224 if (usermodehelper_disabled == UMH_DISABLED)
223 ret = -EAGAIN; 225 ret = -EAGAIN;
224 226
225 up_read(&umhelper_sem); 227 up_read(&umhelper_sem);
226 228
227 if (ret) 229 if (ret)
228 break; 230 break;
229 231
230 schedule(); 232 schedule();
231 try_to_freeze(); 233 try_to_freeze();
232 234
233 down_read(&umhelper_sem); 235 down_read(&umhelper_sem);
234 } 236 }
235 finish_wait(&usermodehelper_disabled_w 237 finish_wait(&usermodehelper_disabled_waitq, &wait);
236 return ret; 238 return ret;
237 } 239 }
238 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock) 240 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
239 241
240 long usermodehelper_read_lock_wait(long timeou 242 long usermodehelper_read_lock_wait(long timeout)
241 { 243 {
242 DEFINE_WAIT(wait); 244 DEFINE_WAIT(wait);
243 245
244 if (timeout < 0) 246 if (timeout < 0)
245 return -EINVAL; 247 return -EINVAL;
246 248
247 down_read(&umhelper_sem); 249 down_read(&umhelper_sem);
248 for (;;) { 250 for (;;) {
249 prepare_to_wait(&usermodehelpe 251 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
250 TASK_UNINTERRU 252 TASK_UNINTERRUPTIBLE);
251 if (!usermodehelper_disabled) 253 if (!usermodehelper_disabled)
252 break; 254 break;
253 255
254 up_read(&umhelper_sem); 256 up_read(&umhelper_sem);
255 257
256 timeout = schedule_timeout(tim 258 timeout = schedule_timeout(timeout);
257 if (!timeout) 259 if (!timeout)
258 break; 260 break;
259 261
260 down_read(&umhelper_sem); 262 down_read(&umhelper_sem);
261 } 263 }
262 finish_wait(&usermodehelper_disabled_w 264 finish_wait(&usermodehelper_disabled_waitq, &wait);
263 return timeout; 265 return timeout;
264 } 266 }
265 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wai 267 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
266 268
267 void usermodehelper_read_unlock(void) 269 void usermodehelper_read_unlock(void)
268 { 270 {
269 up_read(&umhelper_sem); 271 up_read(&umhelper_sem);
270 } 272 }
271 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); 273 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
272 274
273 /** 275 /**
274 * __usermodehelper_set_disable_depth - Modify 276 * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
275 * @depth: New value to assign to usermodehelp 277 * @depth: New value to assign to usermodehelper_disabled.
276 * 278 *
277 * Change the value of usermodehelper_disabled 279 * Change the value of usermodehelper_disabled (under umhelper_sem locked for
278 * writing) and wakeup tasks waiting for it to 280 * writing) and wakeup tasks waiting for it to change.
279 */ 281 */
280 void __usermodehelper_set_disable_depth(enum u 282 void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
281 { 283 {
282 down_write(&umhelper_sem); 284 down_write(&umhelper_sem);
283 usermodehelper_disabled = depth; 285 usermodehelper_disabled = depth;
284 wake_up(&usermodehelper_disabled_waitq 286 wake_up(&usermodehelper_disabled_waitq);
285 up_write(&umhelper_sem); 287 up_write(&umhelper_sem);
286 } 288 }
287 289
288 /** 290 /**
289 * __usermodehelper_disable - Prevent new help 291 * __usermodehelper_disable - Prevent new helpers from being started.
290 * @depth: New value to assign to usermodehelp 292 * @depth: New value to assign to usermodehelper_disabled.
291 * 293 *
292 * Set usermodehelper_disabled to @depth and w 294 * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
293 */ 295 */
294 int __usermodehelper_disable(enum umh_disable_ 296 int __usermodehelper_disable(enum umh_disable_depth depth)
295 { 297 {
296 long retval; 298 long retval;
297 299
298 if (!depth) 300 if (!depth)
299 return -EINVAL; 301 return -EINVAL;
300 302
301 down_write(&umhelper_sem); 303 down_write(&umhelper_sem);
302 usermodehelper_disabled = depth; 304 usermodehelper_disabled = depth;
303 up_write(&umhelper_sem); 305 up_write(&umhelper_sem);
304 306
305 /* 307 /*
306 * From now on call_usermodehelper_exe 308 * From now on call_usermodehelper_exec() won't start any new
307 * helpers, so it is sufficient if run 309 * helpers, so it is sufficient if running_helpers turns out to
308 * be zero at one point (it may be inc 310 * be zero at one point (it may be increased later, but that
309 * doesn't matter). 311 * doesn't matter).
310 */ 312 */
311 retval = wait_event_timeout(running_he 313 retval = wait_event_timeout(running_helpers_waitq,
312 atomic 314 atomic_read(&running_helpers) == 0,
313 RUNNIN 315 RUNNING_HELPERS_TIMEOUT);
314 if (retval) 316 if (retval)
315 return 0; 317 return 0;
316 318
317 __usermodehelper_set_disable_depth(UMH 319 __usermodehelper_set_disable_depth(UMH_ENABLED);
318 return -EAGAIN; 320 return -EAGAIN;
319 } 321 }
320 322
321 static void helper_lock(void) 323 static void helper_lock(void)
322 { 324 {
323 atomic_inc(&running_helpers); 325 atomic_inc(&running_helpers);
324 smp_mb__after_atomic(); 326 smp_mb__after_atomic();
325 } 327 }
326 328
327 static void helper_unlock(void) 329 static void helper_unlock(void)
328 { 330 {
329 if (atomic_dec_and_test(&running_helpe 331 if (atomic_dec_and_test(&running_helpers))
330 wake_up(&running_helpers_waitq 332 wake_up(&running_helpers_waitq);
331 } 333 }
332 334
333 /** 335 /**
334 * call_usermodehelper_setup - prepare to call 336 * call_usermodehelper_setup - prepare to call a usermode helper
335 * @path: path to usermode executable 337 * @path: path to usermode executable
336 * @argv: arg vector for process 338 * @argv: arg vector for process
337 * @envp: environment for process 339 * @envp: environment for process
338 * @gfp_mask: gfp mask for memory allocation 340 * @gfp_mask: gfp mask for memory allocation
339 * @init: an init function 341 * @init: an init function
340 * @cleanup: a cleanup function 342 * @cleanup: a cleanup function
341 * @data: arbitrary context sensitive data 343 * @data: arbitrary context sensitive data
342 * 344 *
343 * Returns either %NULL on allocation failure, 345 * Returns either %NULL on allocation failure, or a subprocess_info
344 * structure. This should be passed to call_u 346 * structure. This should be passed to call_usermodehelper_exec to
345 * exec the process and free the structure. 347 * exec the process and free the structure.
346 * 348 *
347 * The init function is used to customize the 349 * The init function is used to customize the helper process prior to
348 * exec. A non-zero return code causes the pr 350 * exec. A non-zero return code causes the process to error out, exit,
349 * and return the failure to the calling proce 351 * and return the failure to the calling process
350 * 352 *
351 * The cleanup function is just before the sub 353 * The cleanup function is just before the subprocess_info is about to
352 * be freed. This can be used for freeing the 354 * be freed. This can be used for freeing the argv and envp. The
353 * Function must be runnable in either a proce 355 * Function must be runnable in either a process context or the
354 * context in which call_usermodehelper_exec i 356 * context in which call_usermodehelper_exec is called.
355 */ 357 */
356 struct subprocess_info *call_usermodehelper_se 358 struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv,
357 char **envp, gfp_t gfp_mask, 359 char **envp, gfp_t gfp_mask,
358 int (*init)(struct subprocess_ 360 int (*init)(struct subprocess_info *info, struct cred *new),
359 void (*cleanup)(struct subproc 361 void (*cleanup)(struct subprocess_info *info),
360 void *data) 362 void *data)
361 { 363 {
362 struct subprocess_info *sub_info; 364 struct subprocess_info *sub_info;
363 sub_info = kzalloc(sizeof(struct subpr 365 sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
364 if (!sub_info) 366 if (!sub_info)
365 goto out; 367 goto out;
366 368
367 INIT_WORK(&sub_info->work, call_usermo 369 INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
368 370
369 #ifdef CONFIG_STATIC_USERMODEHELPER 371 #ifdef CONFIG_STATIC_USERMODEHELPER
370 sub_info->path = CONFIG_STATIC_USERMOD 372 sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH;
371 #else 373 #else
372 sub_info->path = path; 374 sub_info->path = path;
373 #endif 375 #endif
374 sub_info->argv = argv; 376 sub_info->argv = argv;
375 sub_info->envp = envp; 377 sub_info->envp = envp;
376 378
377 sub_info->cleanup = cleanup; 379 sub_info->cleanup = cleanup;
378 sub_info->init = init; 380 sub_info->init = init;
379 sub_info->data = data; 381 sub_info->data = data;
380 out: 382 out:
381 return sub_info; 383 return sub_info;
382 } 384 }
383 EXPORT_SYMBOL(call_usermodehelper_setup); 385 EXPORT_SYMBOL(call_usermodehelper_setup);
384 386
385 /** 387 /**
386 * call_usermodehelper_exec - start a usermode 388 * call_usermodehelper_exec - start a usermode application
387 * @sub_info: information about the subprocess 389 * @sub_info: information about the subprocess
388 * @wait: wait for the application to finish a 390 * @wait: wait for the application to finish and return status.
389 * when UMH_NO_WAIT don't wait at all, 391 * when UMH_NO_WAIT don't wait at all, but you get no useful error back
390 * when the program couldn't be exec'ed 392 * when the program couldn't be exec'ed. This makes it safe to call
391 * from interrupt context. 393 * from interrupt context.
392 * 394 *
393 * Runs a user-space application. The applica 395 * Runs a user-space application. The application is started
394 * asynchronously if wait is not set, and runs 396 * asynchronously if wait is not set, and runs as a child of system workqueues.
395 * (ie. it runs with full root capabilities an 397 * (ie. it runs with full root capabilities and optimized affinity).
396 * 398 *
397 * Note: successful return value does not guar 399 * Note: successful return value does not guarantee the helper was called at
398 * all. You can't rely on sub_info->{init,clea 400 * all. You can't rely on sub_info->{init,cleanup} being called even for
399 * UMH_WAIT_* wait modes as STATIC_USERMODEHEL 401 * UMH_WAIT_* wait modes as STATIC_USERMODEHELPER_PATH="" turns all helpers
400 * into a successful no-op. 402 * into a successful no-op.
401 */ 403 */
402 int call_usermodehelper_exec(struct subprocess 404 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
403 { 405 {
404 unsigned int state = TASK_UNINTERRUPTI <<
405 DECLARE_COMPLETION_ONSTACK(done); 406 DECLARE_COMPLETION_ONSTACK(done);
406 int retval = 0; 407 int retval = 0;
407 408
408 if (!sub_info->path) { 409 if (!sub_info->path) {
409 call_usermodehelper_freeinfo(s 410 call_usermodehelper_freeinfo(sub_info);
410 return -EINVAL; 411 return -EINVAL;
411 } 412 }
412 helper_lock(); 413 helper_lock();
413 if (usermodehelper_disabled) { 414 if (usermodehelper_disabled) {
414 retval = -EBUSY; 415 retval = -EBUSY;
415 goto out; 416 goto out;
416 } 417 }
417 418
418 /* 419 /*
419 * If there is no binary for us to cal 420 * If there is no binary for us to call, then just return and get out of
420 * here. This allows us to set STATIC 421 * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and
421 * disable all call_usermodehelper() c 422 * disable all call_usermodehelper() calls.
422 */ 423 */
423 if (strlen(sub_info->path) == 0) 424 if (strlen(sub_info->path) == 0)
424 goto out; 425 goto out;
425 426
426 /* 427 /*
427 * Set the completion pointer only if 428 * Set the completion pointer only if there is a waiter.
428 * This makes it possible to use umh_c 429 * This makes it possible to use umh_complete to free
429 * the data structure in case of UMH_N 430 * the data structure in case of UMH_NO_WAIT.
430 */ 431 */
431 sub_info->complete = (wait == UMH_NO_W 432 sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
432 sub_info->wait = wait; 433 sub_info->wait = wait;
433 434
434 queue_work(system_unbound_wq, &sub_inf 435 queue_work(system_unbound_wq, &sub_info->work);
435 if (wait == UMH_NO_WAIT) /* tas 436 if (wait == UMH_NO_WAIT) /* task has freed sub_info */
436 goto unlock; 437 goto unlock;
437 438
438 if (wait & UMH_FREEZABLE) <<
439 state |= TASK_FREEZABLE; <<
440 <<
441 if (wait & UMH_KILLABLE) { 439 if (wait & UMH_KILLABLE) {
442 retval = wait_for_completion_s !! 440 retval = wait_for_completion_killable(&done);
443 if (!retval) 441 if (!retval)
444 goto wait_done; 442 goto wait_done;
445 443
446 /* umh_complete() will see NUL 444 /* umh_complete() will see NULL and free sub_info */
447 if (xchg(&sub_info->complete, 445 if (xchg(&sub_info->complete, NULL))
448 goto unlock; 446 goto unlock;
449 !! 447 /* fallthrough, umh_complete() was already called */
450 /* <<
451 * fallthrough; in case of -ER <<
452 * wait_for_completion_state() <<
453 * complete() in a moment if x <<
454 * uninterruptible wait_for_co <<
455 * SIGKILL'ed processes for lo <<
456 */ <<
457 } 448 }
458 wait_for_completion_state(&done, state <<
459 449
>> 450 wait_for_completion(&done);
460 wait_done: 451 wait_done:
461 retval = sub_info->retval; 452 retval = sub_info->retval;
462 out: 453 out:
463 call_usermodehelper_freeinfo(sub_info) 454 call_usermodehelper_freeinfo(sub_info);
464 unlock: 455 unlock:
465 helper_unlock(); 456 helper_unlock();
466 return retval; 457 return retval;
467 } 458 }
468 EXPORT_SYMBOL(call_usermodehelper_exec); 459 EXPORT_SYMBOL(call_usermodehelper_exec);
469 460
470 /** 461 /**
471 * call_usermodehelper() - prepare and start a 462 * call_usermodehelper() - prepare and start a usermode application
472 * @path: path to usermode executable 463 * @path: path to usermode executable
473 * @argv: arg vector for process 464 * @argv: arg vector for process
474 * @envp: environment for process 465 * @envp: environment for process
475 * @wait: wait for the application to finish a 466 * @wait: wait for the application to finish and return status.
476 * when UMH_NO_WAIT don't wait at all, 467 * when UMH_NO_WAIT don't wait at all, but you get no useful error back
477 * when the program couldn't be exec'ed 468 * when the program couldn't be exec'ed. This makes it safe to call
478 * from interrupt context. 469 * from interrupt context.
479 * 470 *
480 * This function is the equivalent to use call 471 * This function is the equivalent to use call_usermodehelper_setup() and
481 * call_usermodehelper_exec(). 472 * call_usermodehelper_exec().
482 */ 473 */
483 int call_usermodehelper(const char *path, char 474 int call_usermodehelper(const char *path, char **argv, char **envp, int wait)
484 { 475 {
485 struct subprocess_info *info; 476 struct subprocess_info *info;
486 gfp_t gfp_mask = (wait == UMH_NO_WAIT) 477 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
487 478
488 info = call_usermodehelper_setup(path, 479 info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
489 NULL, 480 NULL, NULL, NULL);
490 if (info == NULL) 481 if (info == NULL)
491 return -ENOMEM; 482 return -ENOMEM;
492 483
493 return call_usermodehelper_exec(info, 484 return call_usermodehelper_exec(info, wait);
494 } 485 }
495 EXPORT_SYMBOL(call_usermodehelper); 486 EXPORT_SYMBOL(call_usermodehelper);
496 487
497 #if defined(CONFIG_SYSCTL) !! 488 static int proc_cap_handler(struct ctl_table *table, int write,
498 static int proc_cap_handler(const struct ctl_t <<
499 void *buffer, size_t 489 void *buffer, size_t *lenp, loff_t *ppos)
500 { 490 {
501 struct ctl_table t; 491 struct ctl_table t;
502 unsigned long cap_array[2]; !! 492 unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
503 kernel_cap_t new_cap, *cap; !! 493 kernel_cap_t new_cap;
504 int err; !! 494 int err, i;
505 495
506 if (write && (!capable(CAP_SETPCAP) || 496 if (write && (!capable(CAP_SETPCAP) ||
507 !capable(CAP_SYS_MODULE) 497 !capable(CAP_SYS_MODULE)))
508 return -EPERM; 498 return -EPERM;
509 499
510 /* 500 /*
511 * convert from the global kernel_cap_ 501 * convert from the global kernel_cap_t to the ulong array to print to
512 * userspace if this is a read. 502 * userspace if this is a read.
513 * <<
514 * Legacy format: capabilities are exp <<
515 */ 503 */
516 cap = table->data; <<
517 spin_lock(&umh_sysctl_lock); 504 spin_lock(&umh_sysctl_lock);
518 cap_array[0] = (u32) cap->val; !! 505 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
519 cap_array[1] = cap->val >> 32; !! 506 if (table->data == CAP_BSET)
>> 507 cap_array[i] = usermodehelper_bset.cap[i];
>> 508 else if (table->data == CAP_PI)
>> 509 cap_array[i] = usermodehelper_inheritable.cap[i];
>> 510 else
>> 511 BUG();
>> 512 }
520 spin_unlock(&umh_sysctl_lock); 513 spin_unlock(&umh_sysctl_lock);
521 514
522 t = *table; 515 t = *table;
523 t.data = &cap_array; 516 t.data = &cap_array;
524 517
525 /* 518 /*
526 * actually read or write and array of 519 * actually read or write and array of ulongs from userspace. Remember
527 * these are least significant 32 bits 520 * these are least significant 32 bits first
528 */ 521 */
529 err = proc_doulongvec_minmax(&t, write 522 err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
530 if (err < 0) 523 if (err < 0)
531 return err; 524 return err;
532 525
533 new_cap.val = (u32)cap_array[0]; !! 526 /*
534 new_cap.val += (u64)cap_array[1] << 32 !! 527 * convert from the sysctl array of ulongs to the kernel_cap_t
>> 528 * internal representation
>> 529 */
>> 530 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
>> 531 new_cap.cap[i] = cap_array[i];
535 532
536 /* 533 /*
537 * Drop everything not in the new_cap 534 * Drop everything not in the new_cap (but don't add things)
538 */ 535 */
539 if (write) { 536 if (write) {
540 spin_lock(&umh_sysctl_lock); 537 spin_lock(&umh_sysctl_lock);
541 *cap = cap_intersect(*cap, new !! 538 if (table->data == CAP_BSET)
>> 539 usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
>> 540 if (table->data == CAP_PI)
>> 541 usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
542 spin_unlock(&umh_sysctl_lock); 542 spin_unlock(&umh_sysctl_lock);
543 } 543 }
544 544
545 return 0; 545 return 0;
546 } 546 }
547 547
548 static struct ctl_table usermodehelper_table[] !! 548 struct ctl_table usermodehelper_table[] = {
549 { 549 {
550 .procname = "bset", 550 .procname = "bset",
551 .data = &usermodehel !! 551 .data = CAP_BSET,
552 .maxlen = 2 * sizeof(u !! 552 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
553 .mode = 0600, 553 .mode = 0600,
554 .proc_handler = proc_cap_han 554 .proc_handler = proc_cap_handler,
555 }, 555 },
556 { 556 {
557 .procname = "inheritable 557 .procname = "inheritable",
558 .data = &usermodehel !! 558 .data = CAP_PI,
559 .maxlen = 2 * sizeof(u !! 559 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
560 .mode = 0600, 560 .mode = 0600,
561 .proc_handler = proc_cap_han 561 .proc_handler = proc_cap_handler,
562 }, 562 },
>> 563 { }
563 }; 564 };
564 <<
565 static int __init init_umh_sysctls(void) <<
566 { <<
567 register_sysctl_init("kernel/usermodeh <<
568 return 0; <<
569 } <<
570 early_initcall(init_umh_sysctls); <<
571 #endif /* CONFIG_SYSCTL */ <<
572 565
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