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> 31 #include <linux/freezer.h>
32 32
33 #include <trace/events/module.h> 33 #include <trace/events/module.h>
34 34
>> 35 #define CAP_BSET (void *)1
>> 36 #define CAP_PI (void *)2
>> 37
35 static kernel_cap_t usermodehelper_bset = CAP_ 38 static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
36 static kernel_cap_t usermodehelper_inheritable 39 static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
37 static DEFINE_SPINLOCK(umh_sysctl_lock); 40 static DEFINE_SPINLOCK(umh_sysctl_lock);
38 static DECLARE_RWSEM(umhelper_sem); 41 static DECLARE_RWSEM(umhelper_sem);
39 42
40 static void call_usermodehelper_freeinfo(struc 43 static void call_usermodehelper_freeinfo(struct subprocess_info *info)
41 { 44 {
42 if (info->cleanup) 45 if (info->cleanup)
43 (*info->cleanup)(info); 46 (*info->cleanup)(info);
44 kfree(info); 47 kfree(info);
45 } 48 }
46 49
47 static void umh_complete(struct subprocess_inf 50 static void umh_complete(struct subprocess_info *sub_info)
48 { 51 {
49 struct completion *comp = xchg(&sub_in 52 struct completion *comp = xchg(&sub_info->complete, NULL);
50 /* 53 /*
51 * See call_usermodehelper_exec(). If 54 * See call_usermodehelper_exec(). If xchg() returns NULL
52 * we own sub_info, the UMH_KILLABLE c 55 * we own sub_info, the UMH_KILLABLE caller has gone away
53 * or the caller used UMH_NO_WAIT. 56 * or the caller used UMH_NO_WAIT.
54 */ 57 */
55 if (comp) 58 if (comp)
56 complete(comp); 59 complete(comp);
57 else 60 else
58 call_usermodehelper_freeinfo(s 61 call_usermodehelper_freeinfo(sub_info);
59 } 62 }
60 63
61 /* 64 /*
62 * This is the task which runs the usermode ap 65 * This is the task which runs the usermode application
63 */ 66 */
64 static int call_usermodehelper_exec_async(void 67 static int call_usermodehelper_exec_async(void *data)
65 { 68 {
66 struct subprocess_info *sub_info = dat 69 struct subprocess_info *sub_info = data;
67 struct cred *new; 70 struct cred *new;
68 int retval; 71 int retval;
69 72
70 spin_lock_irq(¤t->sighand->siglo 73 spin_lock_irq(¤t->sighand->siglock);
71 flush_signal_handlers(current, 1); 74 flush_signal_handlers(current, 1);
72 spin_unlock_irq(¤t->sighand->sig 75 spin_unlock_irq(¤t->sighand->siglock);
73 76
74 /* 77 /*
75 * Initial kernel threads share ther F 78 * Initial kernel threads share ther FS with init, in order to
76 * get the init root directory. But we 79 * get the init root directory. But we've now created a new
77 * thread that is going to execve a us 80 * thread that is going to execve a user process and has its own
78 * 'struct fs_struct'. Reset umask to 81 * 'struct fs_struct'. Reset umask to the default.
79 */ 82 */
80 current->fs->umask = 0022; 83 current->fs->umask = 0022;
81 84
82 /* 85 /*
83 * Our parent (unbound workqueue) runs 86 * Our parent (unbound workqueue) runs with elevated scheduling
84 * priority. Avoid propagating that in 87 * priority. Avoid propagating that into the userspace child.
85 */ 88 */
86 set_user_nice(current, 0); 89 set_user_nice(current, 0);
87 90
88 retval = -ENOMEM; 91 retval = -ENOMEM;
89 new = prepare_kernel_cred(current); 92 new = prepare_kernel_cred(current);
90 if (!new) 93 if (!new)
91 goto out; 94 goto out;
92 95
93 spin_lock(&umh_sysctl_lock); 96 spin_lock(&umh_sysctl_lock);
94 new->cap_bset = cap_intersect(usermode 97 new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
95 new->cap_inheritable = cap_intersect(u 98 new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
96 n 99 new->cap_inheritable);
97 spin_unlock(&umh_sysctl_lock); 100 spin_unlock(&umh_sysctl_lock);
98 101
99 if (sub_info->init) { 102 if (sub_info->init) {
100 retval = sub_info->init(sub_in 103 retval = sub_info->init(sub_info, new);
101 if (retval) { 104 if (retval) {
102 abort_creds(new); 105 abort_creds(new);
103 goto out; 106 goto out;
104 } 107 }
105 } 108 }
106 109
107 commit_creds(new); 110 commit_creds(new);
108 111
109 wait_for_initramfs(); 112 wait_for_initramfs();
110 retval = kernel_execve(sub_info->path, 113 retval = kernel_execve(sub_info->path,
111 (const char *co 114 (const char *const *)sub_info->argv,
112 (const char *co 115 (const char *const *)sub_info->envp);
113 out: 116 out:
114 sub_info->retval = retval; 117 sub_info->retval = retval;
115 /* 118 /*
116 * call_usermodehelper_exec_sync() wil 119 * call_usermodehelper_exec_sync() will call umh_complete
117 * if UHM_WAIT_PROC. 120 * if UHM_WAIT_PROC.
118 */ 121 */
119 if (!(sub_info->wait & UMH_WAIT_PROC)) 122 if (!(sub_info->wait & UMH_WAIT_PROC))
120 umh_complete(sub_info); 123 umh_complete(sub_info);
121 if (!retval) 124 if (!retval)
122 return 0; 125 return 0;
123 do_exit(0); 126 do_exit(0);
124 } 127 }
125 128
126 /* Handles UMH_WAIT_PROC. */ 129 /* Handles UMH_WAIT_PROC. */
127 static void call_usermodehelper_exec_sync(stru 130 static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
128 { 131 {
129 pid_t pid; 132 pid_t pid;
130 133
131 /* If SIGCLD is ignored do_wait won't 134 /* If SIGCLD is ignored do_wait won't populate the status. */
132 kernel_sigaction(SIGCHLD, SIG_DFL); 135 kernel_sigaction(SIGCHLD, SIG_DFL);
133 pid = user_mode_thread(call_usermodehe 136 pid = user_mode_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
134 if (pid < 0) 137 if (pid < 0)
135 sub_info->retval = pid; 138 sub_info->retval = pid;
136 else 139 else
137 kernel_wait(pid, &sub_info->re 140 kernel_wait(pid, &sub_info->retval);
138 141
139 /* Restore default kernel sig handler 142 /* Restore default kernel sig handler */
140 kernel_sigaction(SIGCHLD, SIG_IGN); 143 kernel_sigaction(SIGCHLD, SIG_IGN);
141 umh_complete(sub_info); 144 umh_complete(sub_info);
142 } 145 }
143 146
144 /* 147 /*
145 * We need to create the usermodehelper kernel 148 * We need to create the usermodehelper kernel thread from a task that is affine
146 * to an optimized set of CPUs (or nohz housek 149 * to an optimized set of CPUs (or nohz housekeeping ones) such that they
147 * inherit a widest affinity irrespective of c 150 * inherit a widest affinity irrespective of call_usermodehelper() callers with
148 * possibly reduced affinity (eg: per-cpu work 151 * possibly reduced affinity (eg: per-cpu workqueues). We don't want
149 * usermodehelper targets to contend a busy CP 152 * usermodehelper targets to contend a busy CPU.
150 * 153 *
151 * Unbound workqueues provide such wide affini 154 * Unbound workqueues provide such wide affinity and allow to block on
152 * UMH_WAIT_PROC requests without blocking pen 155 * UMH_WAIT_PROC requests without blocking pending request (up to some limit).
153 * 156 *
154 * Besides, workqueues provide the privilege l 157 * Besides, workqueues provide the privilege level that caller might not have
155 * to perform the usermodehelper request. 158 * to perform the usermodehelper request.
156 * 159 *
157 */ 160 */
158 static void call_usermodehelper_exec_work(stru 161 static void call_usermodehelper_exec_work(struct work_struct *work)
159 { 162 {
160 struct subprocess_info *sub_info = 163 struct subprocess_info *sub_info =
161 container_of(work, struct subp 164 container_of(work, struct subprocess_info, work);
162 165
163 if (sub_info->wait & UMH_WAIT_PROC) { 166 if (sub_info->wait & UMH_WAIT_PROC) {
164 call_usermodehelper_exec_sync( 167 call_usermodehelper_exec_sync(sub_info);
165 } else { 168 } else {
166 pid_t pid; 169 pid_t pid;
167 /* 170 /*
168 * Use CLONE_PARENT to reparen 171 * Use CLONE_PARENT to reparent it to kthreadd; we do not
169 * want to pollute current->ch 172 * want to pollute current->children, and we need a parent
170 * that always ignores SIGCHLD 173 * that always ignores SIGCHLD to ensure auto-reaping.
171 */ 174 */
172 pid = user_mode_thread(call_us 175 pid = user_mode_thread(call_usermodehelper_exec_async, sub_info,
173 CLONE_P 176 CLONE_PARENT | SIGCHLD);
174 if (pid < 0) { 177 if (pid < 0) {
175 sub_info->retval = pid 178 sub_info->retval = pid;
176 umh_complete(sub_info) 179 umh_complete(sub_info);
177 } 180 }
178 } 181 }
179 } 182 }
180 183
181 /* 184 /*
182 * If set, call_usermodehelper_exec() will exi 185 * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
183 * (used for preventing user land processes fr 186 * (used for preventing user land processes from being created after the user
184 * land has been frozen during a system-wide h 187 * land has been frozen during a system-wide hibernation or suspend operation).
185 * Should always be manipulated under umhelper 188 * Should always be manipulated under umhelper_sem acquired for write.
186 */ 189 */
187 static enum umh_disable_depth usermodehelper_d 190 static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
188 191
189 /* Number of helpers running */ 192 /* Number of helpers running */
190 static atomic_t running_helpers = ATOMIC_INIT( 193 static atomic_t running_helpers = ATOMIC_INIT(0);
191 194
192 /* 195 /*
193 * Wait queue head used by usermodehelper_disa 196 * Wait queue head used by usermodehelper_disable() to wait for all running
194 * helpers to finish. 197 * helpers to finish.
195 */ 198 */
196 static DECLARE_WAIT_QUEUE_HEAD(running_helpers 199 static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
197 200
198 /* 201 /*
199 * Used by usermodehelper_read_lock_wait() to 202 * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
200 * to become 'false'. 203 * to become 'false'.
201 */ 204 */
202 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_ 205 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
203 206
204 /* 207 /*
205 * Time to wait for running_helpers to become 208 * Time to wait for running_helpers to become zero before the setting of
206 * usermodehelper_disabled in usermodehelper_d 209 * usermodehelper_disabled in usermodehelper_disable() fails
207 */ 210 */
208 #define RUNNING_HELPERS_TIMEOUT (5 * HZ) 211 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
209 212
210 int usermodehelper_read_trylock(void) 213 int usermodehelper_read_trylock(void)
211 { 214 {
212 DEFINE_WAIT(wait); 215 DEFINE_WAIT(wait);
213 int ret = 0; 216 int ret = 0;
214 217
215 down_read(&umhelper_sem); 218 down_read(&umhelper_sem);
216 for (;;) { 219 for (;;) {
217 prepare_to_wait(&usermodehelpe 220 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
218 TASK_INTERRUPT 221 TASK_INTERRUPTIBLE);
219 if (!usermodehelper_disabled) 222 if (!usermodehelper_disabled)
220 break; 223 break;
221 224
222 if (usermodehelper_disabled == 225 if (usermodehelper_disabled == UMH_DISABLED)
223 ret = -EAGAIN; 226 ret = -EAGAIN;
224 227
225 up_read(&umhelper_sem); 228 up_read(&umhelper_sem);
226 229
227 if (ret) 230 if (ret)
228 break; 231 break;
229 232
230 schedule(); 233 schedule();
231 try_to_freeze(); 234 try_to_freeze();
232 235
233 down_read(&umhelper_sem); 236 down_read(&umhelper_sem);
234 } 237 }
235 finish_wait(&usermodehelper_disabled_w 238 finish_wait(&usermodehelper_disabled_waitq, &wait);
236 return ret; 239 return ret;
237 } 240 }
238 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock) 241 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
239 242
240 long usermodehelper_read_lock_wait(long timeou 243 long usermodehelper_read_lock_wait(long timeout)
241 { 244 {
242 DEFINE_WAIT(wait); 245 DEFINE_WAIT(wait);
243 246
244 if (timeout < 0) 247 if (timeout < 0)
245 return -EINVAL; 248 return -EINVAL;
246 249
247 down_read(&umhelper_sem); 250 down_read(&umhelper_sem);
248 for (;;) { 251 for (;;) {
249 prepare_to_wait(&usermodehelpe 252 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
250 TASK_UNINTERRU 253 TASK_UNINTERRUPTIBLE);
251 if (!usermodehelper_disabled) 254 if (!usermodehelper_disabled)
252 break; 255 break;
253 256
254 up_read(&umhelper_sem); 257 up_read(&umhelper_sem);
255 258
256 timeout = schedule_timeout(tim 259 timeout = schedule_timeout(timeout);
257 if (!timeout) 260 if (!timeout)
258 break; 261 break;
259 262
260 down_read(&umhelper_sem); 263 down_read(&umhelper_sem);
261 } 264 }
262 finish_wait(&usermodehelper_disabled_w 265 finish_wait(&usermodehelper_disabled_waitq, &wait);
263 return timeout; 266 return timeout;
264 } 267 }
265 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wai 268 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
266 269
267 void usermodehelper_read_unlock(void) 270 void usermodehelper_read_unlock(void)
268 { 271 {
269 up_read(&umhelper_sem); 272 up_read(&umhelper_sem);
270 } 273 }
271 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); 274 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
272 275
273 /** 276 /**
274 * __usermodehelper_set_disable_depth - Modify 277 * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
275 * @depth: New value to assign to usermodehelp 278 * @depth: New value to assign to usermodehelper_disabled.
276 * 279 *
277 * Change the value of usermodehelper_disabled 280 * Change the value of usermodehelper_disabled (under umhelper_sem locked for
278 * writing) and wakeup tasks waiting for it to 281 * writing) and wakeup tasks waiting for it to change.
279 */ 282 */
280 void __usermodehelper_set_disable_depth(enum u 283 void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
281 { 284 {
282 down_write(&umhelper_sem); 285 down_write(&umhelper_sem);
283 usermodehelper_disabled = depth; 286 usermodehelper_disabled = depth;
284 wake_up(&usermodehelper_disabled_waitq 287 wake_up(&usermodehelper_disabled_waitq);
285 up_write(&umhelper_sem); 288 up_write(&umhelper_sem);
286 } 289 }
287 290
288 /** 291 /**
289 * __usermodehelper_disable - Prevent new help 292 * __usermodehelper_disable - Prevent new helpers from being started.
290 * @depth: New value to assign to usermodehelp 293 * @depth: New value to assign to usermodehelper_disabled.
291 * 294 *
292 * Set usermodehelper_disabled to @depth and w 295 * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
293 */ 296 */
294 int __usermodehelper_disable(enum umh_disable_ 297 int __usermodehelper_disable(enum umh_disable_depth depth)
295 { 298 {
296 long retval; 299 long retval;
297 300
298 if (!depth) 301 if (!depth)
299 return -EINVAL; 302 return -EINVAL;
300 303
301 down_write(&umhelper_sem); 304 down_write(&umhelper_sem);
302 usermodehelper_disabled = depth; 305 usermodehelper_disabled = depth;
303 up_write(&umhelper_sem); 306 up_write(&umhelper_sem);
304 307
305 /* 308 /*
306 * From now on call_usermodehelper_exe 309 * From now on call_usermodehelper_exec() won't start any new
307 * helpers, so it is sufficient if run 310 * helpers, so it is sufficient if running_helpers turns out to
308 * be zero at one point (it may be inc 311 * be zero at one point (it may be increased later, but that
309 * doesn't matter). 312 * doesn't matter).
310 */ 313 */
311 retval = wait_event_timeout(running_he 314 retval = wait_event_timeout(running_helpers_waitq,
312 atomic 315 atomic_read(&running_helpers) == 0,
313 RUNNIN 316 RUNNING_HELPERS_TIMEOUT);
314 if (retval) 317 if (retval)
315 return 0; 318 return 0;
316 319
317 __usermodehelper_set_disable_depth(UMH 320 __usermodehelper_set_disable_depth(UMH_ENABLED);
318 return -EAGAIN; 321 return -EAGAIN;
319 } 322 }
320 323
321 static void helper_lock(void) 324 static void helper_lock(void)
322 { 325 {
323 atomic_inc(&running_helpers); 326 atomic_inc(&running_helpers);
324 smp_mb__after_atomic(); 327 smp_mb__after_atomic();
325 } 328 }
326 329
327 static void helper_unlock(void) 330 static void helper_unlock(void)
328 { 331 {
329 if (atomic_dec_and_test(&running_helpe 332 if (atomic_dec_and_test(&running_helpers))
330 wake_up(&running_helpers_waitq 333 wake_up(&running_helpers_waitq);
331 } 334 }
332 335
333 /** 336 /**
334 * call_usermodehelper_setup - prepare to call 337 * call_usermodehelper_setup - prepare to call a usermode helper
335 * @path: path to usermode executable 338 * @path: path to usermode executable
336 * @argv: arg vector for process 339 * @argv: arg vector for process
337 * @envp: environment for process 340 * @envp: environment for process
338 * @gfp_mask: gfp mask for memory allocation 341 * @gfp_mask: gfp mask for memory allocation
339 * @init: an init function 342 * @init: an init function
340 * @cleanup: a cleanup function 343 * @cleanup: a cleanup function
341 * @data: arbitrary context sensitive data 344 * @data: arbitrary context sensitive data
342 * 345 *
343 * Returns either %NULL on allocation failure, 346 * Returns either %NULL on allocation failure, or a subprocess_info
344 * structure. This should be passed to call_u 347 * structure. This should be passed to call_usermodehelper_exec to
345 * exec the process and free the structure. 348 * exec the process and free the structure.
346 * 349 *
347 * The init function is used to customize the 350 * The init function is used to customize the helper process prior to
348 * exec. A non-zero return code causes the pr 351 * exec. A non-zero return code causes the process to error out, exit,
349 * and return the failure to the calling proce 352 * and return the failure to the calling process
350 * 353 *
351 * The cleanup function is just before the sub 354 * The cleanup function is just before the subprocess_info is about to
352 * be freed. This can be used for freeing the 355 * be freed. This can be used for freeing the argv and envp. The
353 * Function must be runnable in either a proce 356 * Function must be runnable in either a process context or the
354 * context in which call_usermodehelper_exec i 357 * context in which call_usermodehelper_exec is called.
355 */ 358 */
356 struct subprocess_info *call_usermodehelper_se 359 struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv,
357 char **envp, gfp_t gfp_mask, 360 char **envp, gfp_t gfp_mask,
358 int (*init)(struct subprocess_ 361 int (*init)(struct subprocess_info *info, struct cred *new),
359 void (*cleanup)(struct subproc 362 void (*cleanup)(struct subprocess_info *info),
360 void *data) 363 void *data)
361 { 364 {
362 struct subprocess_info *sub_info; 365 struct subprocess_info *sub_info;
363 sub_info = kzalloc(sizeof(struct subpr 366 sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
364 if (!sub_info) 367 if (!sub_info)
365 goto out; 368 goto out;
366 369
367 INIT_WORK(&sub_info->work, call_usermo 370 INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
368 371
369 #ifdef CONFIG_STATIC_USERMODEHELPER 372 #ifdef CONFIG_STATIC_USERMODEHELPER
370 sub_info->path = CONFIG_STATIC_USERMOD 373 sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH;
371 #else 374 #else
372 sub_info->path = path; 375 sub_info->path = path;
373 #endif 376 #endif
374 sub_info->argv = argv; 377 sub_info->argv = argv;
375 sub_info->envp = envp; 378 sub_info->envp = envp;
376 379
377 sub_info->cleanup = cleanup; 380 sub_info->cleanup = cleanup;
378 sub_info->init = init; 381 sub_info->init = init;
379 sub_info->data = data; 382 sub_info->data = data;
380 out: 383 out:
381 return sub_info; 384 return sub_info;
382 } 385 }
383 EXPORT_SYMBOL(call_usermodehelper_setup); 386 EXPORT_SYMBOL(call_usermodehelper_setup);
384 387
385 /** 388 /**
386 * call_usermodehelper_exec - start a usermode 389 * call_usermodehelper_exec - start a usermode application
387 * @sub_info: information about the subprocess 390 * @sub_info: information about the subprocess
388 * @wait: wait for the application to finish a 391 * @wait: wait for the application to finish and return status.
389 * when UMH_NO_WAIT don't wait at all, 392 * 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 393 * when the program couldn't be exec'ed. This makes it safe to call
391 * from interrupt context. 394 * from interrupt context.
392 * 395 *
393 * Runs a user-space application. The applica 396 * Runs a user-space application. The application is started
394 * asynchronously if wait is not set, and runs 397 * asynchronously if wait is not set, and runs as a child of system workqueues.
395 * (ie. it runs with full root capabilities an 398 * (ie. it runs with full root capabilities and optimized affinity).
396 * 399 *
397 * Note: successful return value does not guar 400 * Note: successful return value does not guarantee the helper was called at
398 * all. You can't rely on sub_info->{init,clea 401 * all. You can't rely on sub_info->{init,cleanup} being called even for
399 * UMH_WAIT_* wait modes as STATIC_USERMODEHEL 402 * UMH_WAIT_* wait modes as STATIC_USERMODEHELPER_PATH="" turns all helpers
400 * into a successful no-op. 403 * into a successful no-op.
401 */ 404 */
402 int call_usermodehelper_exec(struct subprocess 405 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
403 { 406 {
404 unsigned int state = TASK_UNINTERRUPTI 407 unsigned int state = TASK_UNINTERRUPTIBLE;
405 DECLARE_COMPLETION_ONSTACK(done); 408 DECLARE_COMPLETION_ONSTACK(done);
406 int retval = 0; 409 int retval = 0;
407 410
408 if (!sub_info->path) { 411 if (!sub_info->path) {
409 call_usermodehelper_freeinfo(s 412 call_usermodehelper_freeinfo(sub_info);
410 return -EINVAL; 413 return -EINVAL;
411 } 414 }
412 helper_lock(); 415 helper_lock();
413 if (usermodehelper_disabled) { 416 if (usermodehelper_disabled) {
414 retval = -EBUSY; 417 retval = -EBUSY;
415 goto out; 418 goto out;
416 } 419 }
417 420
418 /* 421 /*
419 * If there is no binary for us to cal 422 * If there is no binary for us to call, then just return and get out of
420 * here. This allows us to set STATIC 423 * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and
421 * disable all call_usermodehelper() c 424 * disable all call_usermodehelper() calls.
422 */ 425 */
423 if (strlen(sub_info->path) == 0) 426 if (strlen(sub_info->path) == 0)
424 goto out; 427 goto out;
425 428
426 /* 429 /*
427 * Set the completion pointer only if 430 * Set the completion pointer only if there is a waiter.
428 * This makes it possible to use umh_c 431 * This makes it possible to use umh_complete to free
429 * the data structure in case of UMH_N 432 * the data structure in case of UMH_NO_WAIT.
430 */ 433 */
431 sub_info->complete = (wait == UMH_NO_W 434 sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
432 sub_info->wait = wait; 435 sub_info->wait = wait;
433 436
434 queue_work(system_unbound_wq, &sub_inf 437 queue_work(system_unbound_wq, &sub_info->work);
435 if (wait == UMH_NO_WAIT) /* tas 438 if (wait == UMH_NO_WAIT) /* task has freed sub_info */
436 goto unlock; 439 goto unlock;
437 440
438 if (wait & UMH_FREEZABLE) 441 if (wait & UMH_FREEZABLE)
439 state |= TASK_FREEZABLE; 442 state |= TASK_FREEZABLE;
440 443
441 if (wait & UMH_KILLABLE) { 444 if (wait & UMH_KILLABLE) {
442 retval = wait_for_completion_s 445 retval = wait_for_completion_state(&done, state | TASK_KILLABLE);
443 if (!retval) 446 if (!retval)
444 goto wait_done; 447 goto wait_done;
445 448
446 /* umh_complete() will see NUL 449 /* umh_complete() will see NULL and free sub_info */
447 if (xchg(&sub_info->complete, 450 if (xchg(&sub_info->complete, NULL))
448 goto unlock; 451 goto unlock;
449 452
450 /* 453 /*
451 * fallthrough; in case of -ER 454 * fallthrough; in case of -ERESTARTSYS now do uninterruptible
452 * wait_for_completion_state() 455 * wait_for_completion_state(). Since umh_complete() shall call
453 * complete() in a moment if x 456 * complete() in a moment if xchg() above returned NULL, this
454 * uninterruptible wait_for_co 457 * uninterruptible wait_for_completion_state() will not block
455 * SIGKILL'ed processes for lo 458 * SIGKILL'ed processes for long.
456 */ 459 */
457 } 460 }
458 wait_for_completion_state(&done, state 461 wait_for_completion_state(&done, state);
459 462
460 wait_done: 463 wait_done:
461 retval = sub_info->retval; 464 retval = sub_info->retval;
462 out: 465 out:
463 call_usermodehelper_freeinfo(sub_info) 466 call_usermodehelper_freeinfo(sub_info);
464 unlock: 467 unlock:
465 helper_unlock(); 468 helper_unlock();
466 return retval; 469 return retval;
467 } 470 }
468 EXPORT_SYMBOL(call_usermodehelper_exec); 471 EXPORT_SYMBOL(call_usermodehelper_exec);
469 472
470 /** 473 /**
471 * call_usermodehelper() - prepare and start a 474 * call_usermodehelper() - prepare and start a usermode application
472 * @path: path to usermode executable 475 * @path: path to usermode executable
473 * @argv: arg vector for process 476 * @argv: arg vector for process
474 * @envp: environment for process 477 * @envp: environment for process
475 * @wait: wait for the application to finish a 478 * @wait: wait for the application to finish and return status.
476 * when UMH_NO_WAIT don't wait at all, 479 * 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 480 * when the program couldn't be exec'ed. This makes it safe to call
478 * from interrupt context. 481 * from interrupt context.
479 * 482 *
480 * This function is the equivalent to use call 483 * This function is the equivalent to use call_usermodehelper_setup() and
481 * call_usermodehelper_exec(). 484 * call_usermodehelper_exec().
482 */ 485 */
483 int call_usermodehelper(const char *path, char 486 int call_usermodehelper(const char *path, char **argv, char **envp, int wait)
484 { 487 {
485 struct subprocess_info *info; 488 struct subprocess_info *info;
486 gfp_t gfp_mask = (wait == UMH_NO_WAIT) 489 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
487 490
488 info = call_usermodehelper_setup(path, 491 info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
489 NULL, 492 NULL, NULL, NULL);
490 if (info == NULL) 493 if (info == NULL)
491 return -ENOMEM; 494 return -ENOMEM;
492 495
493 return call_usermodehelper_exec(info, 496 return call_usermodehelper_exec(info, wait);
494 } 497 }
495 EXPORT_SYMBOL(call_usermodehelper); 498 EXPORT_SYMBOL(call_usermodehelper);
496 499
497 #if defined(CONFIG_SYSCTL) !! 500 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 501 void *buffer, size_t *lenp, loff_t *ppos)
500 { 502 {
501 struct ctl_table t; 503 struct ctl_table t;
502 unsigned long cap_array[2]; !! 504 unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
503 kernel_cap_t new_cap, *cap; !! 505 kernel_cap_t new_cap;
504 int err; !! 506 int err, i;
505 507
506 if (write && (!capable(CAP_SETPCAP) || 508 if (write && (!capable(CAP_SETPCAP) ||
507 !capable(CAP_SYS_MODULE) 509 !capable(CAP_SYS_MODULE)))
508 return -EPERM; 510 return -EPERM;
509 511
510 /* 512 /*
511 * convert from the global kernel_cap_ 513 * convert from the global kernel_cap_t to the ulong array to print to
512 * userspace if this is a read. 514 * userspace if this is a read.
513 * <<
514 * Legacy format: capabilities are exp <<
515 */ 515 */
516 cap = table->data; <<
517 spin_lock(&umh_sysctl_lock); 516 spin_lock(&umh_sysctl_lock);
518 cap_array[0] = (u32) cap->val; !! 517 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
519 cap_array[1] = cap->val >> 32; !! 518 if (table->data == CAP_BSET)
>> 519 cap_array[i] = usermodehelper_bset.cap[i];
>> 520 else if (table->data == CAP_PI)
>> 521 cap_array[i] = usermodehelper_inheritable.cap[i];
>> 522 else
>> 523 BUG();
>> 524 }
520 spin_unlock(&umh_sysctl_lock); 525 spin_unlock(&umh_sysctl_lock);
521 526
522 t = *table; 527 t = *table;
523 t.data = &cap_array; 528 t.data = &cap_array;
524 529
525 /* 530 /*
526 * actually read or write and array of 531 * actually read or write and array of ulongs from userspace. Remember
527 * these are least significant 32 bits 532 * these are least significant 32 bits first
528 */ 533 */
529 err = proc_doulongvec_minmax(&t, write 534 err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
530 if (err < 0) 535 if (err < 0)
531 return err; 536 return err;
532 537
533 new_cap.val = (u32)cap_array[0]; !! 538 /*
534 new_cap.val += (u64)cap_array[1] << 32 !! 539 * convert from the sysctl array of ulongs to the kernel_cap_t
>> 540 * internal representation
>> 541 */
>> 542 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
>> 543 new_cap.cap[i] = cap_array[i];
535 544
536 /* 545 /*
537 * Drop everything not in the new_cap 546 * Drop everything not in the new_cap (but don't add things)
538 */ 547 */
539 if (write) { 548 if (write) {
540 spin_lock(&umh_sysctl_lock); 549 spin_lock(&umh_sysctl_lock);
541 *cap = cap_intersect(*cap, new !! 550 if (table->data == CAP_BSET)
>> 551 usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
>> 552 if (table->data == CAP_PI)
>> 553 usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
542 spin_unlock(&umh_sysctl_lock); 554 spin_unlock(&umh_sysctl_lock);
543 } 555 }
544 556
545 return 0; 557 return 0;
546 } 558 }
547 559
548 static struct ctl_table usermodehelper_table[] !! 560 struct ctl_table usermodehelper_table[] = {
549 { 561 {
550 .procname = "bset", 562 .procname = "bset",
551 .data = &usermodehel !! 563 .data = CAP_BSET,
552 .maxlen = 2 * sizeof(u !! 564 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
553 .mode = 0600, 565 .mode = 0600,
554 .proc_handler = proc_cap_han 566 .proc_handler = proc_cap_handler,
555 }, 567 },
556 { 568 {
557 .procname = "inheritable 569 .procname = "inheritable",
558 .data = &usermodehel !! 570 .data = CAP_PI,
559 .maxlen = 2 * sizeof(u !! 571 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
560 .mode = 0600, 572 .mode = 0600,
561 .proc_handler = proc_cap_han 573 .proc_handler = proc_cap_handler,
562 }, 574 },
>> 575 { }
563 }; 576 };
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 */ <<
572 577
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