1 // SPDX-License-Identifier: GPL-2.0-only <<
2 /* 1 /*
3 * umh - the kernel usermode helper 2 * umh - the kernel usermode helper
4 */ 3 */
5 #include <linux/module.h> 4 #include <linux/module.h>
6 #include <linux/sched.h> 5 #include <linux/sched.h>
7 #include <linux/sched/task.h> 6 #include <linux/sched/task.h>
8 #include <linux/binfmts.h> 7 #include <linux/binfmts.h>
9 #include <linux/syscalls.h> 8 #include <linux/syscalls.h>
10 #include <linux/unistd.h> 9 #include <linux/unistd.h>
11 #include <linux/kmod.h> 10 #include <linux/kmod.h>
12 #include <linux/slab.h> 11 #include <linux/slab.h>
13 #include <linux/completion.h> 12 #include <linux/completion.h>
14 #include <linux/cred.h> 13 #include <linux/cred.h>
15 #include <linux/file.h> 14 #include <linux/file.h>
16 #include <linux/fdtable.h> 15 #include <linux/fdtable.h>
17 #include <linux/fs_struct.h> <<
18 #include <linux/workqueue.h> 16 #include <linux/workqueue.h>
19 #include <linux/security.h> 17 #include <linux/security.h>
20 #include <linux/mount.h> 18 #include <linux/mount.h>
21 #include <linux/kernel.h> 19 #include <linux/kernel.h>
22 #include <linux/init.h> 20 #include <linux/init.h>
23 #include <linux/resource.h> 21 #include <linux/resource.h>
24 #include <linux/notifier.h> 22 #include <linux/notifier.h>
25 #include <linux/suspend.h> 23 #include <linux/suspend.h>
26 #include <linux/rwsem.h> 24 #include <linux/rwsem.h>
27 #include <linux/ptrace.h> 25 #include <linux/ptrace.h>
28 #include <linux/async.h> 26 #include <linux/async.h>
29 #include <linux/uaccess.h> 27 #include <linux/uaccess.h>
30 #include <linux/initrd.h> <<
31 #include <linux/freezer.h> <<
32 28
33 #include <trace/events/module.h> 29 #include <trace/events/module.h>
34 30
>> 31 #define CAP_BSET (void *)1
>> 32 #define CAP_PI (void *)2
>> 33
35 static kernel_cap_t usermodehelper_bset = CAP_ 34 static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
36 static kernel_cap_t usermodehelper_inheritable 35 static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
37 static DEFINE_SPINLOCK(umh_sysctl_lock); 36 static DEFINE_SPINLOCK(umh_sysctl_lock);
38 static DECLARE_RWSEM(umhelper_sem); 37 static DECLARE_RWSEM(umhelper_sem);
39 38
40 static void call_usermodehelper_freeinfo(struc 39 static void call_usermodehelper_freeinfo(struct subprocess_info *info)
41 { 40 {
42 if (info->cleanup) 41 if (info->cleanup)
43 (*info->cleanup)(info); 42 (*info->cleanup)(info);
44 kfree(info); 43 kfree(info);
45 } 44 }
46 45
47 static void umh_complete(struct subprocess_inf 46 static void umh_complete(struct subprocess_info *sub_info)
48 { 47 {
49 struct completion *comp = xchg(&sub_in 48 struct completion *comp = xchg(&sub_info->complete, NULL);
50 /* 49 /*
51 * See call_usermodehelper_exec(). If 50 * See call_usermodehelper_exec(). If xchg() returns NULL
52 * we own sub_info, the UMH_KILLABLE c 51 * we own sub_info, the UMH_KILLABLE caller has gone away
53 * or the caller used UMH_NO_WAIT. 52 * or the caller used UMH_NO_WAIT.
54 */ 53 */
55 if (comp) 54 if (comp)
56 complete(comp); 55 complete(comp);
57 else 56 else
58 call_usermodehelper_freeinfo(s 57 call_usermodehelper_freeinfo(sub_info);
59 } 58 }
60 59
61 /* 60 /*
62 * This is the task which runs the usermode ap 61 * This is the task which runs the usermode application
63 */ 62 */
64 static int call_usermodehelper_exec_async(void 63 static int call_usermodehelper_exec_async(void *data)
65 { 64 {
66 struct subprocess_info *sub_info = dat 65 struct subprocess_info *sub_info = data;
67 struct cred *new; 66 struct cred *new;
68 int retval; 67 int retval;
69 68
70 spin_lock_irq(¤t->sighand->siglo 69 spin_lock_irq(¤t->sighand->siglock);
71 flush_signal_handlers(current, 1); 70 flush_signal_handlers(current, 1);
72 spin_unlock_irq(¤t->sighand->sig 71 spin_unlock_irq(¤t->sighand->siglock);
73 72
74 /* 73 /*
75 * Initial kernel threads share ther F <<
76 * get the init root directory. But we <<
77 * thread that is going to execve a us <<
78 * 'struct fs_struct'. Reset umask to <<
79 */ <<
80 current->fs->umask = 0022; <<
81 <<
82 /* <<
83 * Our parent (unbound workqueue) runs 74 * Our parent (unbound workqueue) runs with elevated scheduling
84 * priority. Avoid propagating that in 75 * priority. Avoid propagating that into the userspace child.
85 */ 76 */
86 set_user_nice(current, 0); 77 set_user_nice(current, 0);
87 78
88 retval = -ENOMEM; 79 retval = -ENOMEM;
89 new = prepare_kernel_cred(current); 80 new = prepare_kernel_cred(current);
90 if (!new) 81 if (!new)
91 goto out; 82 goto out;
92 83
93 spin_lock(&umh_sysctl_lock); 84 spin_lock(&umh_sysctl_lock);
94 new->cap_bset = cap_intersect(usermode 85 new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
95 new->cap_inheritable = cap_intersect(u 86 new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
96 n 87 new->cap_inheritable);
97 spin_unlock(&umh_sysctl_lock); 88 spin_unlock(&umh_sysctl_lock);
98 89
99 if (sub_info->init) { 90 if (sub_info->init) {
100 retval = sub_info->init(sub_in 91 retval = sub_info->init(sub_info, new);
101 if (retval) { 92 if (retval) {
102 abort_creds(new); 93 abort_creds(new);
103 goto out; 94 goto out;
104 } 95 }
105 } 96 }
106 97
107 commit_creds(new); 98 commit_creds(new);
108 99
109 wait_for_initramfs(); !! 100 retval = do_execve(getname_kernel(sub_info->path),
110 retval = kernel_execve(sub_info->path, !! 101 (const char __user *const __user *)sub_info->argv,
111 (const char *co !! 102 (const char __user *const __user *)sub_info->envp);
112 (const char *co <<
113 out: 103 out:
114 sub_info->retval = retval; 104 sub_info->retval = retval;
115 /* 105 /*
116 * call_usermodehelper_exec_sync() wil 106 * call_usermodehelper_exec_sync() will call umh_complete
117 * if UHM_WAIT_PROC. 107 * if UHM_WAIT_PROC.
118 */ 108 */
119 if (!(sub_info->wait & UMH_WAIT_PROC)) 109 if (!(sub_info->wait & UMH_WAIT_PROC))
120 umh_complete(sub_info); 110 umh_complete(sub_info);
121 if (!retval) 111 if (!retval)
122 return 0; 112 return 0;
123 do_exit(0); 113 do_exit(0);
124 } 114 }
125 115
126 /* Handles UMH_WAIT_PROC. */ 116 /* Handles UMH_WAIT_PROC. */
127 static void call_usermodehelper_exec_sync(stru 117 static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
128 { 118 {
129 pid_t pid; 119 pid_t pid;
130 120
131 /* If SIGCLD is ignored do_wait won't !! 121 /* If SIGCLD is ignored kernel_wait4 won't populate the status. */
132 kernel_sigaction(SIGCHLD, SIG_DFL); 122 kernel_sigaction(SIGCHLD, SIG_DFL);
133 pid = user_mode_thread(call_usermodehe !! 123 pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
134 if (pid < 0) !! 124 if (pid < 0) {
135 sub_info->retval = pid; 125 sub_info->retval = pid;
136 else !! 126 } else {
137 kernel_wait(pid, &sub_info->re !! 127 int ret = -ECHILD;
>> 128 /*
>> 129 * Normally it is bogus to call wait4() from in-kernel because
>> 130 * wait4() wants to write the exit code to a userspace address.
>> 131 * But call_usermodehelper_exec_sync() always runs as kernel
>> 132 * thread (workqueue) and put_user() to a kernel address works
>> 133 * OK for kernel threads, due to their having an mm_segment_t
>> 134 * which spans the entire address space.
>> 135 *
>> 136 * Thus the __user pointer cast is valid here.
>> 137 */
>> 138 kernel_wait4(pid, (int __user *)&ret, 0, NULL);
>> 139
>> 140 /*
>> 141 * If ret is 0, either call_usermodehelper_exec_async failed and
>> 142 * the real error code is already in sub_info->retval or
>> 143 * sub_info->retval is 0 anyway, so don't mess with it then.
>> 144 */
>> 145 if (ret)
>> 146 sub_info->retval = ret;
>> 147 }
138 148
139 /* Restore default kernel sig handler 149 /* Restore default kernel sig handler */
140 kernel_sigaction(SIGCHLD, SIG_IGN); 150 kernel_sigaction(SIGCHLD, SIG_IGN);
>> 151
141 umh_complete(sub_info); 152 umh_complete(sub_info);
142 } 153 }
143 154
144 /* 155 /*
145 * We need to create the usermodehelper kernel 156 * We need to create the usermodehelper kernel thread from a task that is affine
146 * to an optimized set of CPUs (or nohz housek 157 * to an optimized set of CPUs (or nohz housekeeping ones) such that they
147 * inherit a widest affinity irrespective of c 158 * inherit a widest affinity irrespective of call_usermodehelper() callers with
148 * possibly reduced affinity (eg: per-cpu work 159 * possibly reduced affinity (eg: per-cpu workqueues). We don't want
149 * usermodehelper targets to contend a busy CP 160 * usermodehelper targets to contend a busy CPU.
150 * 161 *
151 * Unbound workqueues provide such wide affini 162 * Unbound workqueues provide such wide affinity and allow to block on
152 * UMH_WAIT_PROC requests without blocking pen 163 * UMH_WAIT_PROC requests without blocking pending request (up to some limit).
153 * 164 *
154 * Besides, workqueues provide the privilege l 165 * Besides, workqueues provide the privilege level that caller might not have
155 * to perform the usermodehelper request. 166 * to perform the usermodehelper request.
156 * 167 *
157 */ 168 */
158 static void call_usermodehelper_exec_work(stru 169 static void call_usermodehelper_exec_work(struct work_struct *work)
159 { 170 {
160 struct subprocess_info *sub_info = 171 struct subprocess_info *sub_info =
161 container_of(work, struct subp 172 container_of(work, struct subprocess_info, work);
162 173
163 if (sub_info->wait & UMH_WAIT_PROC) { 174 if (sub_info->wait & UMH_WAIT_PROC) {
164 call_usermodehelper_exec_sync( 175 call_usermodehelper_exec_sync(sub_info);
165 } else { 176 } else {
166 pid_t pid; 177 pid_t pid;
167 /* 178 /*
168 * Use CLONE_PARENT to reparen 179 * Use CLONE_PARENT to reparent it to kthreadd; we do not
169 * want to pollute current->ch 180 * want to pollute current->children, and we need a parent
170 * that always ignores SIGCHLD 181 * that always ignores SIGCHLD to ensure auto-reaping.
171 */ 182 */
172 pid = user_mode_thread(call_us !! 183 pid = kernel_thread(call_usermodehelper_exec_async, sub_info,
173 CLONE_P !! 184 CLONE_PARENT | SIGCHLD);
174 if (pid < 0) { 185 if (pid < 0) {
175 sub_info->retval = pid 186 sub_info->retval = pid;
176 umh_complete(sub_info) 187 umh_complete(sub_info);
177 } 188 }
178 } 189 }
179 } 190 }
180 191
181 /* 192 /*
182 * If set, call_usermodehelper_exec() will exi 193 * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
183 * (used for preventing user land processes fr 194 * (used for preventing user land processes from being created after the user
184 * land has been frozen during a system-wide h 195 * land has been frozen during a system-wide hibernation or suspend operation).
185 * Should always be manipulated under umhelper 196 * Should always be manipulated under umhelper_sem acquired for write.
186 */ 197 */
187 static enum umh_disable_depth usermodehelper_d 198 static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
188 199
189 /* Number of helpers running */ 200 /* Number of helpers running */
190 static atomic_t running_helpers = ATOMIC_INIT( 201 static atomic_t running_helpers = ATOMIC_INIT(0);
191 202
192 /* 203 /*
193 * Wait queue head used by usermodehelper_disa 204 * Wait queue head used by usermodehelper_disable() to wait for all running
194 * helpers to finish. 205 * helpers to finish.
195 */ 206 */
196 static DECLARE_WAIT_QUEUE_HEAD(running_helpers 207 static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
197 208
198 /* 209 /*
199 * Used by usermodehelper_read_lock_wait() to 210 * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
200 * to become 'false'. 211 * to become 'false'.
201 */ 212 */
202 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_ 213 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
203 214
204 /* 215 /*
205 * Time to wait for running_helpers to become 216 * Time to wait for running_helpers to become zero before the setting of
206 * usermodehelper_disabled in usermodehelper_d 217 * usermodehelper_disabled in usermodehelper_disable() fails
207 */ 218 */
208 #define RUNNING_HELPERS_TIMEOUT (5 * HZ) 219 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
209 220
210 int usermodehelper_read_trylock(void) 221 int usermodehelper_read_trylock(void)
211 { 222 {
212 DEFINE_WAIT(wait); 223 DEFINE_WAIT(wait);
213 int ret = 0; 224 int ret = 0;
214 225
215 down_read(&umhelper_sem); 226 down_read(&umhelper_sem);
216 for (;;) { 227 for (;;) {
217 prepare_to_wait(&usermodehelpe 228 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
218 TASK_INTERRUPT 229 TASK_INTERRUPTIBLE);
219 if (!usermodehelper_disabled) 230 if (!usermodehelper_disabled)
220 break; 231 break;
221 232
222 if (usermodehelper_disabled == 233 if (usermodehelper_disabled == UMH_DISABLED)
223 ret = -EAGAIN; 234 ret = -EAGAIN;
224 235
225 up_read(&umhelper_sem); 236 up_read(&umhelper_sem);
226 237
227 if (ret) 238 if (ret)
228 break; 239 break;
229 240
230 schedule(); 241 schedule();
231 try_to_freeze(); 242 try_to_freeze();
232 243
233 down_read(&umhelper_sem); 244 down_read(&umhelper_sem);
234 } 245 }
235 finish_wait(&usermodehelper_disabled_w 246 finish_wait(&usermodehelper_disabled_waitq, &wait);
236 return ret; 247 return ret;
237 } 248 }
238 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock) 249 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
239 250
240 long usermodehelper_read_lock_wait(long timeou 251 long usermodehelper_read_lock_wait(long timeout)
241 { 252 {
242 DEFINE_WAIT(wait); 253 DEFINE_WAIT(wait);
243 254
244 if (timeout < 0) 255 if (timeout < 0)
245 return -EINVAL; 256 return -EINVAL;
246 257
247 down_read(&umhelper_sem); 258 down_read(&umhelper_sem);
248 for (;;) { 259 for (;;) {
249 prepare_to_wait(&usermodehelpe 260 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
250 TASK_UNINTERRU 261 TASK_UNINTERRUPTIBLE);
251 if (!usermodehelper_disabled) 262 if (!usermodehelper_disabled)
252 break; 263 break;
253 264
254 up_read(&umhelper_sem); 265 up_read(&umhelper_sem);
255 266
256 timeout = schedule_timeout(tim 267 timeout = schedule_timeout(timeout);
257 if (!timeout) 268 if (!timeout)
258 break; 269 break;
259 270
260 down_read(&umhelper_sem); 271 down_read(&umhelper_sem);
261 } 272 }
262 finish_wait(&usermodehelper_disabled_w 273 finish_wait(&usermodehelper_disabled_waitq, &wait);
263 return timeout; 274 return timeout;
264 } 275 }
265 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wai 276 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
266 277
267 void usermodehelper_read_unlock(void) 278 void usermodehelper_read_unlock(void)
268 { 279 {
269 up_read(&umhelper_sem); 280 up_read(&umhelper_sem);
270 } 281 }
271 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); 282 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
272 283
273 /** 284 /**
274 * __usermodehelper_set_disable_depth - Modify 285 * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
275 * @depth: New value to assign to usermodehelp 286 * @depth: New value to assign to usermodehelper_disabled.
276 * 287 *
277 * Change the value of usermodehelper_disabled 288 * Change the value of usermodehelper_disabled (under umhelper_sem locked for
278 * writing) and wakeup tasks waiting for it to 289 * writing) and wakeup tasks waiting for it to change.
279 */ 290 */
280 void __usermodehelper_set_disable_depth(enum u 291 void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
281 { 292 {
282 down_write(&umhelper_sem); 293 down_write(&umhelper_sem);
283 usermodehelper_disabled = depth; 294 usermodehelper_disabled = depth;
284 wake_up(&usermodehelper_disabled_waitq 295 wake_up(&usermodehelper_disabled_waitq);
285 up_write(&umhelper_sem); 296 up_write(&umhelper_sem);
286 } 297 }
287 298
288 /** 299 /**
289 * __usermodehelper_disable - Prevent new help 300 * __usermodehelper_disable - Prevent new helpers from being started.
290 * @depth: New value to assign to usermodehelp 301 * @depth: New value to assign to usermodehelper_disabled.
291 * 302 *
292 * Set usermodehelper_disabled to @depth and w 303 * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
293 */ 304 */
294 int __usermodehelper_disable(enum umh_disable_ 305 int __usermodehelper_disable(enum umh_disable_depth depth)
295 { 306 {
296 long retval; 307 long retval;
297 308
298 if (!depth) 309 if (!depth)
299 return -EINVAL; 310 return -EINVAL;
300 311
301 down_write(&umhelper_sem); 312 down_write(&umhelper_sem);
302 usermodehelper_disabled = depth; 313 usermodehelper_disabled = depth;
303 up_write(&umhelper_sem); 314 up_write(&umhelper_sem);
304 315
305 /* 316 /*
306 * From now on call_usermodehelper_exe 317 * From now on call_usermodehelper_exec() won't start any new
307 * helpers, so it is sufficient if run 318 * helpers, so it is sufficient if running_helpers turns out to
308 * be zero at one point (it may be inc 319 * be zero at one point (it may be increased later, but that
309 * doesn't matter). 320 * doesn't matter).
310 */ 321 */
311 retval = wait_event_timeout(running_he 322 retval = wait_event_timeout(running_helpers_waitq,
312 atomic 323 atomic_read(&running_helpers) == 0,
313 RUNNIN 324 RUNNING_HELPERS_TIMEOUT);
314 if (retval) 325 if (retval)
315 return 0; 326 return 0;
316 327
317 __usermodehelper_set_disable_depth(UMH 328 __usermodehelper_set_disable_depth(UMH_ENABLED);
318 return -EAGAIN; 329 return -EAGAIN;
319 } 330 }
320 331
321 static void helper_lock(void) 332 static void helper_lock(void)
322 { 333 {
323 atomic_inc(&running_helpers); 334 atomic_inc(&running_helpers);
324 smp_mb__after_atomic(); 335 smp_mb__after_atomic();
325 } 336 }
326 337
327 static void helper_unlock(void) 338 static void helper_unlock(void)
328 { 339 {
329 if (atomic_dec_and_test(&running_helpe 340 if (atomic_dec_and_test(&running_helpers))
330 wake_up(&running_helpers_waitq 341 wake_up(&running_helpers_waitq);
331 } 342 }
332 343
333 /** 344 /**
334 * call_usermodehelper_setup - prepare to call 345 * call_usermodehelper_setup - prepare to call a usermode helper
335 * @path: path to usermode executable 346 * @path: path to usermode executable
336 * @argv: arg vector for process 347 * @argv: arg vector for process
337 * @envp: environment for process 348 * @envp: environment for process
338 * @gfp_mask: gfp mask for memory allocation 349 * @gfp_mask: gfp mask for memory allocation
339 * @init: an init function <<
340 * @cleanup: a cleanup function 350 * @cleanup: a cleanup function
>> 351 * @init: an init function
341 * @data: arbitrary context sensitive data 352 * @data: arbitrary context sensitive data
342 * 353 *
343 * Returns either %NULL on allocation failure, 354 * Returns either %NULL on allocation failure, or a subprocess_info
344 * structure. This should be passed to call_u 355 * structure. This should be passed to call_usermodehelper_exec to
345 * exec the process and free the structure. 356 * exec the process and free the structure.
346 * 357 *
347 * The init function is used to customize the 358 * The init function is used to customize the helper process prior to
348 * exec. A non-zero return code causes the pr 359 * exec. A non-zero return code causes the process to error out, exit,
349 * and return the failure to the calling proce 360 * and return the failure to the calling process
350 * 361 *
351 * The cleanup function is just before the sub !! 362 * The cleanup function is just before ethe subprocess_info is about to
352 * be freed. This can be used for freeing the 363 * be freed. This can be used for freeing the argv and envp. The
353 * Function must be runnable in either a proce 364 * Function must be runnable in either a process context or the
354 * context in which call_usermodehelper_exec i 365 * context in which call_usermodehelper_exec is called.
355 */ 366 */
356 struct subprocess_info *call_usermodehelper_se 367 struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv,
357 char **envp, gfp_t gfp_mask, 368 char **envp, gfp_t gfp_mask,
358 int (*init)(struct subprocess_ 369 int (*init)(struct subprocess_info *info, struct cred *new),
359 void (*cleanup)(struct subproc 370 void (*cleanup)(struct subprocess_info *info),
360 void *data) 371 void *data)
361 { 372 {
362 struct subprocess_info *sub_info; 373 struct subprocess_info *sub_info;
363 sub_info = kzalloc(sizeof(struct subpr 374 sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
364 if (!sub_info) 375 if (!sub_info)
365 goto out; 376 goto out;
366 377
367 INIT_WORK(&sub_info->work, call_usermo 378 INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
368 379
369 #ifdef CONFIG_STATIC_USERMODEHELPER 380 #ifdef CONFIG_STATIC_USERMODEHELPER
370 sub_info->path = CONFIG_STATIC_USERMOD 381 sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH;
371 #else 382 #else
372 sub_info->path = path; 383 sub_info->path = path;
373 #endif 384 #endif
374 sub_info->argv = argv; 385 sub_info->argv = argv;
375 sub_info->envp = envp; 386 sub_info->envp = envp;
376 387
377 sub_info->cleanup = cleanup; 388 sub_info->cleanup = cleanup;
378 sub_info->init = init; 389 sub_info->init = init;
379 sub_info->data = data; 390 sub_info->data = data;
380 out: 391 out:
381 return sub_info; 392 return sub_info;
382 } 393 }
383 EXPORT_SYMBOL(call_usermodehelper_setup); 394 EXPORT_SYMBOL(call_usermodehelper_setup);
384 395
385 /** 396 /**
386 * call_usermodehelper_exec - start a usermode 397 * call_usermodehelper_exec - start a usermode application
387 * @sub_info: information about the subprocess !! 398 * @sub_info: information about the subprocessa
388 * @wait: wait for the application to finish a 399 * @wait: wait for the application to finish and return status.
389 * when UMH_NO_WAIT don't wait at all, 400 * 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 401 * when the program couldn't be exec'ed. This makes it safe to call
391 * from interrupt context. 402 * from interrupt context.
392 * 403 *
393 * Runs a user-space application. The applica 404 * Runs a user-space application. The application is started
394 * asynchronously if wait is not set, and runs 405 * asynchronously if wait is not set, and runs as a child of system workqueues.
395 * (ie. it runs with full root capabilities an 406 * (ie. it runs with full root capabilities and optimized affinity).
396 * <<
397 * Note: successful return value does not guar <<
398 * all. You can't rely on sub_info->{init,clea <<
399 * UMH_WAIT_* wait modes as STATIC_USERMODEHEL <<
400 * into a successful no-op. <<
401 */ 407 */
402 int call_usermodehelper_exec(struct subprocess 408 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
403 { 409 {
404 unsigned int state = TASK_UNINTERRUPTI <<
405 DECLARE_COMPLETION_ONSTACK(done); 410 DECLARE_COMPLETION_ONSTACK(done);
406 int retval = 0; 411 int retval = 0;
407 412
408 if (!sub_info->path) { 413 if (!sub_info->path) {
409 call_usermodehelper_freeinfo(s 414 call_usermodehelper_freeinfo(sub_info);
410 return -EINVAL; 415 return -EINVAL;
411 } 416 }
412 helper_lock(); 417 helper_lock();
413 if (usermodehelper_disabled) { 418 if (usermodehelper_disabled) {
414 retval = -EBUSY; 419 retval = -EBUSY;
415 goto out; 420 goto out;
416 } 421 }
417 422
418 /* 423 /*
419 * If there is no binary for us to cal 424 * If there is no binary for us to call, then just return and get out of
420 * here. This allows us to set STATIC 425 * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and
421 * disable all call_usermodehelper() c 426 * disable all call_usermodehelper() calls.
422 */ 427 */
423 if (strlen(sub_info->path) == 0) 428 if (strlen(sub_info->path) == 0)
424 goto out; 429 goto out;
425 430
426 /* 431 /*
427 * Set the completion pointer only if 432 * Set the completion pointer only if there is a waiter.
428 * This makes it possible to use umh_c 433 * This makes it possible to use umh_complete to free
429 * the data structure in case of UMH_N 434 * the data structure in case of UMH_NO_WAIT.
430 */ 435 */
431 sub_info->complete = (wait == UMH_NO_W 436 sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
432 sub_info->wait = wait; 437 sub_info->wait = wait;
433 438
434 queue_work(system_unbound_wq, &sub_inf 439 queue_work(system_unbound_wq, &sub_info->work);
435 if (wait == UMH_NO_WAIT) /* tas 440 if (wait == UMH_NO_WAIT) /* task has freed sub_info */
436 goto unlock; 441 goto unlock;
437 442
438 if (wait & UMH_FREEZABLE) <<
439 state |= TASK_FREEZABLE; <<
440 <<
441 if (wait & UMH_KILLABLE) { 443 if (wait & UMH_KILLABLE) {
442 retval = wait_for_completion_s !! 444 retval = wait_for_completion_killable(&done);
443 if (!retval) 445 if (!retval)
444 goto wait_done; 446 goto wait_done;
445 447
446 /* umh_complete() will see NUL 448 /* umh_complete() will see NULL and free sub_info */
447 if (xchg(&sub_info->complete, 449 if (xchg(&sub_info->complete, NULL))
448 goto unlock; 450 goto unlock;
449 !! 451 /* 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 } 452 }
458 wait_for_completion_state(&done, state <<
459 453
>> 454 wait_for_completion(&done);
460 wait_done: 455 wait_done:
461 retval = sub_info->retval; 456 retval = sub_info->retval;
462 out: 457 out:
463 call_usermodehelper_freeinfo(sub_info) 458 call_usermodehelper_freeinfo(sub_info);
464 unlock: 459 unlock:
465 helper_unlock(); 460 helper_unlock();
466 return retval; 461 return retval;
467 } 462 }
468 EXPORT_SYMBOL(call_usermodehelper_exec); 463 EXPORT_SYMBOL(call_usermodehelper_exec);
469 464
470 /** 465 /**
471 * call_usermodehelper() - prepare and start a 466 * call_usermodehelper() - prepare and start a usermode application
472 * @path: path to usermode executable 467 * @path: path to usermode executable
473 * @argv: arg vector for process 468 * @argv: arg vector for process
474 * @envp: environment for process 469 * @envp: environment for process
475 * @wait: wait for the application to finish a 470 * @wait: wait for the application to finish and return status.
476 * when UMH_NO_WAIT don't wait at all, 471 * 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 472 * when the program couldn't be exec'ed. This makes it safe to call
478 * from interrupt context. 473 * from interrupt context.
479 * 474 *
480 * This function is the equivalent to use call 475 * This function is the equivalent to use call_usermodehelper_setup() and
481 * call_usermodehelper_exec(). 476 * call_usermodehelper_exec().
482 */ 477 */
483 int call_usermodehelper(const char *path, char 478 int call_usermodehelper(const char *path, char **argv, char **envp, int wait)
484 { 479 {
485 struct subprocess_info *info; 480 struct subprocess_info *info;
486 gfp_t gfp_mask = (wait == UMH_NO_WAIT) 481 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
487 482
488 info = call_usermodehelper_setup(path, 483 info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
489 NULL, 484 NULL, NULL, NULL);
490 if (info == NULL) 485 if (info == NULL)
491 return -ENOMEM; 486 return -ENOMEM;
492 487
493 return call_usermodehelper_exec(info, 488 return call_usermodehelper_exec(info, wait);
494 } 489 }
495 EXPORT_SYMBOL(call_usermodehelper); 490 EXPORT_SYMBOL(call_usermodehelper);
496 491
497 #if defined(CONFIG_SYSCTL) !! 492 static int proc_cap_handler(struct ctl_table *table, int write,
498 static int proc_cap_handler(const struct ctl_t !! 493 void __user *buffer, size_t *lenp, loff_t *ppos)
499 void *buffer, size_t <<
500 { 494 {
501 struct ctl_table t; 495 struct ctl_table t;
502 unsigned long cap_array[2]; !! 496 unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
503 kernel_cap_t new_cap, *cap; !! 497 kernel_cap_t new_cap;
504 int err; !! 498 int err, i;
505 499
506 if (write && (!capable(CAP_SETPCAP) || 500 if (write && (!capable(CAP_SETPCAP) ||
507 !capable(CAP_SYS_MODULE) 501 !capable(CAP_SYS_MODULE)))
508 return -EPERM; 502 return -EPERM;
509 503
510 /* 504 /*
511 * convert from the global kernel_cap_ 505 * convert from the global kernel_cap_t to the ulong array to print to
512 * userspace if this is a read. 506 * userspace if this is a read.
513 * <<
514 * Legacy format: capabilities are exp <<
515 */ 507 */
516 cap = table->data; <<
517 spin_lock(&umh_sysctl_lock); 508 spin_lock(&umh_sysctl_lock);
518 cap_array[0] = (u32) cap->val; !! 509 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
519 cap_array[1] = cap->val >> 32; !! 510 if (table->data == CAP_BSET)
>> 511 cap_array[i] = usermodehelper_bset.cap[i];
>> 512 else if (table->data == CAP_PI)
>> 513 cap_array[i] = usermodehelper_inheritable.cap[i];
>> 514 else
>> 515 BUG();
>> 516 }
520 spin_unlock(&umh_sysctl_lock); 517 spin_unlock(&umh_sysctl_lock);
521 518
522 t = *table; 519 t = *table;
523 t.data = &cap_array; 520 t.data = &cap_array;
524 521
525 /* 522 /*
526 * actually read or write and array of 523 * actually read or write and array of ulongs from userspace. Remember
527 * these are least significant 32 bits 524 * these are least significant 32 bits first
528 */ 525 */
529 err = proc_doulongvec_minmax(&t, write 526 err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
530 if (err < 0) 527 if (err < 0)
531 return err; 528 return err;
532 529
533 new_cap.val = (u32)cap_array[0]; !! 530 /*
534 new_cap.val += (u64)cap_array[1] << 32 !! 531 * convert from the sysctl array of ulongs to the kernel_cap_t
>> 532 * internal representation
>> 533 */
>> 534 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
>> 535 new_cap.cap[i] = cap_array[i];
535 536
536 /* 537 /*
537 * Drop everything not in the new_cap 538 * Drop everything not in the new_cap (but don't add things)
538 */ 539 */
539 if (write) { 540 if (write) {
540 spin_lock(&umh_sysctl_lock); 541 spin_lock(&umh_sysctl_lock);
541 *cap = cap_intersect(*cap, new !! 542 if (table->data == CAP_BSET)
>> 543 usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
>> 544 if (table->data == CAP_PI)
>> 545 usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
542 spin_unlock(&umh_sysctl_lock); 546 spin_unlock(&umh_sysctl_lock);
543 } 547 }
544 548
545 return 0; 549 return 0;
546 } 550 }
547 551
548 static struct ctl_table usermodehelper_table[] !! 552 struct ctl_table usermodehelper_table[] = {
549 { 553 {
550 .procname = "bset", 554 .procname = "bset",
551 .data = &usermodehel !! 555 .data = CAP_BSET,
552 .maxlen = 2 * sizeof(u !! 556 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
553 .mode = 0600, 557 .mode = 0600,
554 .proc_handler = proc_cap_han 558 .proc_handler = proc_cap_handler,
555 }, 559 },
556 { 560 {
557 .procname = "inheritable 561 .procname = "inheritable",
558 .data = &usermodehel !! 562 .data = CAP_PI,
559 .maxlen = 2 * sizeof(u !! 563 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
560 .mode = 0600, 564 .mode = 0600,
561 .proc_handler = proc_cap_han 565 .proc_handler = proc_cap_handler,
562 }, 566 },
>> 567 { }
563 }; 568 };
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 */ <<
572 569
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