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/shmem_fs.h>
31 #include <linux/freezer.h> !! 31 #include <linux/pipe_fs_i.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);
>> 42 static LIST_HEAD(umh_list);
>> 43 static DEFINE_MUTEX(umh_list_lock);
39 44
40 static void call_usermodehelper_freeinfo(struc 45 static void call_usermodehelper_freeinfo(struct subprocess_info *info)
41 { 46 {
42 if (info->cleanup) 47 if (info->cleanup)
43 (*info->cleanup)(info); 48 (*info->cleanup)(info);
44 kfree(info); 49 kfree(info);
45 } 50 }
46 51
47 static void umh_complete(struct subprocess_inf 52 static void umh_complete(struct subprocess_info *sub_info)
48 { 53 {
49 struct completion *comp = xchg(&sub_in 54 struct completion *comp = xchg(&sub_info->complete, NULL);
50 /* 55 /*
51 * See call_usermodehelper_exec(). If 56 * See call_usermodehelper_exec(). If xchg() returns NULL
52 * we own sub_info, the UMH_KILLABLE c 57 * we own sub_info, the UMH_KILLABLE caller has gone away
53 * or the caller used UMH_NO_WAIT. 58 * or the caller used UMH_NO_WAIT.
54 */ 59 */
55 if (comp) 60 if (comp)
56 complete(comp); 61 complete(comp);
57 else 62 else
58 call_usermodehelper_freeinfo(s 63 call_usermodehelper_freeinfo(sub_info);
59 } 64 }
60 65
61 /* 66 /*
62 * This is the task which runs the usermode ap 67 * This is the task which runs the usermode application
63 */ 68 */
64 static int call_usermodehelper_exec_async(void 69 static int call_usermodehelper_exec_async(void *data)
65 { 70 {
66 struct subprocess_info *sub_info = dat 71 struct subprocess_info *sub_info = data;
67 struct cred *new; 72 struct cred *new;
68 int retval; 73 int retval;
69 74
70 spin_lock_irq(¤t->sighand->siglo 75 spin_lock_irq(¤t->sighand->siglock);
71 flush_signal_handlers(current, 1); 76 flush_signal_handlers(current, 1);
72 spin_unlock_irq(¤t->sighand->sig 77 spin_unlock_irq(¤t->sighand->siglock);
73 78
74 /* 79 /*
75 * Initial kernel threads share ther F 80 * Initial kernel threads share ther FS with init, in order to
76 * get the init root directory. But we 81 * get the init root directory. But we've now created a new
77 * thread that is going to execve a us 82 * thread that is going to execve a user process and has its own
78 * 'struct fs_struct'. Reset umask to 83 * 'struct fs_struct'. Reset umask to the default.
79 */ 84 */
80 current->fs->umask = 0022; 85 current->fs->umask = 0022;
81 86
82 /* 87 /*
83 * Our parent (unbound workqueue) runs 88 * Our parent (unbound workqueue) runs with elevated scheduling
84 * priority. Avoid propagating that in 89 * priority. Avoid propagating that into the userspace child.
85 */ 90 */
86 set_user_nice(current, 0); 91 set_user_nice(current, 0);
87 92
88 retval = -ENOMEM; 93 retval = -ENOMEM;
89 new = prepare_kernel_cred(current); 94 new = prepare_kernel_cred(current);
90 if (!new) 95 if (!new)
91 goto out; 96 goto out;
92 97
93 spin_lock(&umh_sysctl_lock); 98 spin_lock(&umh_sysctl_lock);
94 new->cap_bset = cap_intersect(usermode 99 new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
95 new->cap_inheritable = cap_intersect(u 100 new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
96 n 101 new->cap_inheritable);
97 spin_unlock(&umh_sysctl_lock); 102 spin_unlock(&umh_sysctl_lock);
98 103
99 if (sub_info->init) { 104 if (sub_info->init) {
100 retval = sub_info->init(sub_in 105 retval = sub_info->init(sub_info, new);
101 if (retval) { 106 if (retval) {
102 abort_creds(new); 107 abort_creds(new);
103 goto out; 108 goto out;
104 } 109 }
105 } 110 }
106 111
107 commit_creds(new); 112 commit_creds(new);
108 113
109 wait_for_initramfs(); !! 114 sub_info->pid = task_pid_nr(current);
110 retval = kernel_execve(sub_info->path, !! 115 if (sub_info->file) {
111 (const char *co !! 116 retval = do_execve_file(sub_info->file,
112 (const char *co !! 117 sub_info->argv, sub_info->envp);
>> 118 if (!retval)
>> 119 current->flags |= PF_UMH;
>> 120 } else
>> 121 retval = do_execve(getname_kernel(sub_info->path),
>> 122 (const char __user *const __user *)sub_info->argv,
>> 123 (const char __user *const __user *)sub_info->envp);
113 out: 124 out:
114 sub_info->retval = retval; 125 sub_info->retval = retval;
115 /* 126 /*
116 * call_usermodehelper_exec_sync() wil 127 * call_usermodehelper_exec_sync() will call umh_complete
117 * if UHM_WAIT_PROC. 128 * if UHM_WAIT_PROC.
118 */ 129 */
119 if (!(sub_info->wait & UMH_WAIT_PROC)) 130 if (!(sub_info->wait & UMH_WAIT_PROC))
120 umh_complete(sub_info); 131 umh_complete(sub_info);
121 if (!retval) 132 if (!retval)
122 return 0; 133 return 0;
123 do_exit(0); 134 do_exit(0);
124 } 135 }
125 136
126 /* Handles UMH_WAIT_PROC. */ 137 /* Handles UMH_WAIT_PROC. */
127 static void call_usermodehelper_exec_sync(stru 138 static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
128 { 139 {
129 pid_t pid; 140 pid_t pid;
130 141
131 /* If SIGCLD is ignored do_wait won't !! 142 /* If SIGCLD is ignored kernel_wait4 won't populate the status. */
132 kernel_sigaction(SIGCHLD, SIG_DFL); 143 kernel_sigaction(SIGCHLD, SIG_DFL);
133 pid = user_mode_thread(call_usermodehe !! 144 pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
134 if (pid < 0) !! 145 if (pid < 0) {
135 sub_info->retval = pid; 146 sub_info->retval = pid;
136 else !! 147 } else {
137 kernel_wait(pid, &sub_info->re !! 148 int ret = -ECHILD;
>> 149 /*
>> 150 * Normally it is bogus to call wait4() from in-kernel because
>> 151 * wait4() wants to write the exit code to a userspace address.
>> 152 * But call_usermodehelper_exec_sync() always runs as kernel
>> 153 * thread (workqueue) and put_user() to a kernel address works
>> 154 * OK for kernel threads, due to their having an mm_segment_t
>> 155 * which spans the entire address space.
>> 156 *
>> 157 * Thus the __user pointer cast is valid here.
>> 158 */
>> 159 kernel_wait4(pid, (int __user *)&ret, 0, NULL);
>> 160
>> 161 /*
>> 162 * If ret is 0, either call_usermodehelper_exec_async failed and
>> 163 * the real error code is already in sub_info->retval or
>> 164 * sub_info->retval is 0 anyway, so don't mess with it then.
>> 165 */
>> 166 if (ret)
>> 167 sub_info->retval = ret;
>> 168 }
138 169
139 /* Restore default kernel sig handler 170 /* Restore default kernel sig handler */
140 kernel_sigaction(SIGCHLD, SIG_IGN); 171 kernel_sigaction(SIGCHLD, SIG_IGN);
>> 172
141 umh_complete(sub_info); 173 umh_complete(sub_info);
142 } 174 }
143 175
144 /* 176 /*
145 * We need to create the usermodehelper kernel 177 * We need to create the usermodehelper kernel thread from a task that is affine
146 * to an optimized set of CPUs (or nohz housek 178 * to an optimized set of CPUs (or nohz housekeeping ones) such that they
147 * inherit a widest affinity irrespective of c 179 * inherit a widest affinity irrespective of call_usermodehelper() callers with
148 * possibly reduced affinity (eg: per-cpu work 180 * possibly reduced affinity (eg: per-cpu workqueues). We don't want
149 * usermodehelper targets to contend a busy CP 181 * usermodehelper targets to contend a busy CPU.
150 * 182 *
151 * Unbound workqueues provide such wide affini 183 * Unbound workqueues provide such wide affinity and allow to block on
152 * UMH_WAIT_PROC requests without blocking pen 184 * UMH_WAIT_PROC requests without blocking pending request (up to some limit).
153 * 185 *
154 * Besides, workqueues provide the privilege l 186 * Besides, workqueues provide the privilege level that caller might not have
155 * to perform the usermodehelper request. 187 * to perform the usermodehelper request.
156 * 188 *
157 */ 189 */
158 static void call_usermodehelper_exec_work(stru 190 static void call_usermodehelper_exec_work(struct work_struct *work)
159 { 191 {
160 struct subprocess_info *sub_info = 192 struct subprocess_info *sub_info =
161 container_of(work, struct subp 193 container_of(work, struct subprocess_info, work);
162 194
163 if (sub_info->wait & UMH_WAIT_PROC) { 195 if (sub_info->wait & UMH_WAIT_PROC) {
164 call_usermodehelper_exec_sync( 196 call_usermodehelper_exec_sync(sub_info);
165 } else { 197 } else {
166 pid_t pid; 198 pid_t pid;
167 /* 199 /*
168 * Use CLONE_PARENT to reparen 200 * Use CLONE_PARENT to reparent it to kthreadd; we do not
169 * want to pollute current->ch 201 * want to pollute current->children, and we need a parent
170 * that always ignores SIGCHLD 202 * that always ignores SIGCHLD to ensure auto-reaping.
171 */ 203 */
172 pid = user_mode_thread(call_us !! 204 pid = kernel_thread(call_usermodehelper_exec_async, sub_info,
173 CLONE_P !! 205 CLONE_PARENT | SIGCHLD);
174 if (pid < 0) { 206 if (pid < 0) {
175 sub_info->retval = pid 207 sub_info->retval = pid;
176 umh_complete(sub_info) 208 umh_complete(sub_info);
177 } 209 }
178 } 210 }
179 } 211 }
180 212
181 /* 213 /*
182 * If set, call_usermodehelper_exec() will exi 214 * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
183 * (used for preventing user land processes fr 215 * (used for preventing user land processes from being created after the user
184 * land has been frozen during a system-wide h 216 * land has been frozen during a system-wide hibernation or suspend operation).
185 * Should always be manipulated under umhelper 217 * Should always be manipulated under umhelper_sem acquired for write.
186 */ 218 */
187 static enum umh_disable_depth usermodehelper_d 219 static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
188 220
189 /* Number of helpers running */ 221 /* Number of helpers running */
190 static atomic_t running_helpers = ATOMIC_INIT( 222 static atomic_t running_helpers = ATOMIC_INIT(0);
191 223
192 /* 224 /*
193 * Wait queue head used by usermodehelper_disa 225 * Wait queue head used by usermodehelper_disable() to wait for all running
194 * helpers to finish. 226 * helpers to finish.
195 */ 227 */
196 static DECLARE_WAIT_QUEUE_HEAD(running_helpers 228 static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
197 229
198 /* 230 /*
199 * Used by usermodehelper_read_lock_wait() to 231 * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
200 * to become 'false'. 232 * to become 'false'.
201 */ 233 */
202 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_ 234 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
203 235
204 /* 236 /*
205 * Time to wait for running_helpers to become 237 * Time to wait for running_helpers to become zero before the setting of
206 * usermodehelper_disabled in usermodehelper_d 238 * usermodehelper_disabled in usermodehelper_disable() fails
207 */ 239 */
208 #define RUNNING_HELPERS_TIMEOUT (5 * HZ) 240 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
209 241
210 int usermodehelper_read_trylock(void) 242 int usermodehelper_read_trylock(void)
211 { 243 {
212 DEFINE_WAIT(wait); 244 DEFINE_WAIT(wait);
213 int ret = 0; 245 int ret = 0;
214 246
215 down_read(&umhelper_sem); 247 down_read(&umhelper_sem);
216 for (;;) { 248 for (;;) {
217 prepare_to_wait(&usermodehelpe 249 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
218 TASK_INTERRUPT 250 TASK_INTERRUPTIBLE);
219 if (!usermodehelper_disabled) 251 if (!usermodehelper_disabled)
220 break; 252 break;
221 253
222 if (usermodehelper_disabled == 254 if (usermodehelper_disabled == UMH_DISABLED)
223 ret = -EAGAIN; 255 ret = -EAGAIN;
224 256
225 up_read(&umhelper_sem); 257 up_read(&umhelper_sem);
226 258
227 if (ret) 259 if (ret)
228 break; 260 break;
229 261
230 schedule(); 262 schedule();
231 try_to_freeze(); 263 try_to_freeze();
232 264
233 down_read(&umhelper_sem); 265 down_read(&umhelper_sem);
234 } 266 }
235 finish_wait(&usermodehelper_disabled_w 267 finish_wait(&usermodehelper_disabled_waitq, &wait);
236 return ret; 268 return ret;
237 } 269 }
238 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock) 270 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
239 271
240 long usermodehelper_read_lock_wait(long timeou 272 long usermodehelper_read_lock_wait(long timeout)
241 { 273 {
242 DEFINE_WAIT(wait); 274 DEFINE_WAIT(wait);
243 275
244 if (timeout < 0) 276 if (timeout < 0)
245 return -EINVAL; 277 return -EINVAL;
246 278
247 down_read(&umhelper_sem); 279 down_read(&umhelper_sem);
248 for (;;) { 280 for (;;) {
249 prepare_to_wait(&usermodehelpe 281 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
250 TASK_UNINTERRU 282 TASK_UNINTERRUPTIBLE);
251 if (!usermodehelper_disabled) 283 if (!usermodehelper_disabled)
252 break; 284 break;
253 285
254 up_read(&umhelper_sem); 286 up_read(&umhelper_sem);
255 287
256 timeout = schedule_timeout(tim 288 timeout = schedule_timeout(timeout);
257 if (!timeout) 289 if (!timeout)
258 break; 290 break;
259 291
260 down_read(&umhelper_sem); 292 down_read(&umhelper_sem);
261 } 293 }
262 finish_wait(&usermodehelper_disabled_w 294 finish_wait(&usermodehelper_disabled_waitq, &wait);
263 return timeout; 295 return timeout;
264 } 296 }
265 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wai 297 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
266 298
267 void usermodehelper_read_unlock(void) 299 void usermodehelper_read_unlock(void)
268 { 300 {
269 up_read(&umhelper_sem); 301 up_read(&umhelper_sem);
270 } 302 }
271 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); 303 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
272 304
273 /** 305 /**
274 * __usermodehelper_set_disable_depth - Modify 306 * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
275 * @depth: New value to assign to usermodehelp 307 * @depth: New value to assign to usermodehelper_disabled.
276 * 308 *
277 * Change the value of usermodehelper_disabled 309 * Change the value of usermodehelper_disabled (under umhelper_sem locked for
278 * writing) and wakeup tasks waiting for it to 310 * writing) and wakeup tasks waiting for it to change.
279 */ 311 */
280 void __usermodehelper_set_disable_depth(enum u 312 void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
281 { 313 {
282 down_write(&umhelper_sem); 314 down_write(&umhelper_sem);
283 usermodehelper_disabled = depth; 315 usermodehelper_disabled = depth;
284 wake_up(&usermodehelper_disabled_waitq 316 wake_up(&usermodehelper_disabled_waitq);
285 up_write(&umhelper_sem); 317 up_write(&umhelper_sem);
286 } 318 }
287 319
288 /** 320 /**
289 * __usermodehelper_disable - Prevent new help 321 * __usermodehelper_disable - Prevent new helpers from being started.
290 * @depth: New value to assign to usermodehelp 322 * @depth: New value to assign to usermodehelper_disabled.
291 * 323 *
292 * Set usermodehelper_disabled to @depth and w 324 * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
293 */ 325 */
294 int __usermodehelper_disable(enum umh_disable_ 326 int __usermodehelper_disable(enum umh_disable_depth depth)
295 { 327 {
296 long retval; 328 long retval;
297 329
298 if (!depth) 330 if (!depth)
299 return -EINVAL; 331 return -EINVAL;
300 332
301 down_write(&umhelper_sem); 333 down_write(&umhelper_sem);
302 usermodehelper_disabled = depth; 334 usermodehelper_disabled = depth;
303 up_write(&umhelper_sem); 335 up_write(&umhelper_sem);
304 336
305 /* 337 /*
306 * From now on call_usermodehelper_exe 338 * From now on call_usermodehelper_exec() won't start any new
307 * helpers, so it is sufficient if run 339 * helpers, so it is sufficient if running_helpers turns out to
308 * be zero at one point (it may be inc 340 * be zero at one point (it may be increased later, but that
309 * doesn't matter). 341 * doesn't matter).
310 */ 342 */
311 retval = wait_event_timeout(running_he 343 retval = wait_event_timeout(running_helpers_waitq,
312 atomic 344 atomic_read(&running_helpers) == 0,
313 RUNNIN 345 RUNNING_HELPERS_TIMEOUT);
314 if (retval) 346 if (retval)
315 return 0; 347 return 0;
316 348
317 __usermodehelper_set_disable_depth(UMH 349 __usermodehelper_set_disable_depth(UMH_ENABLED);
318 return -EAGAIN; 350 return -EAGAIN;
319 } 351 }
320 352
321 static void helper_lock(void) 353 static void helper_lock(void)
322 { 354 {
323 atomic_inc(&running_helpers); 355 atomic_inc(&running_helpers);
324 smp_mb__after_atomic(); 356 smp_mb__after_atomic();
325 } 357 }
326 358
327 static void helper_unlock(void) 359 static void helper_unlock(void)
328 { 360 {
329 if (atomic_dec_and_test(&running_helpe 361 if (atomic_dec_and_test(&running_helpers))
330 wake_up(&running_helpers_waitq 362 wake_up(&running_helpers_waitq);
331 } 363 }
332 364
333 /** 365 /**
334 * call_usermodehelper_setup - prepare to call 366 * call_usermodehelper_setup - prepare to call a usermode helper
335 * @path: path to usermode executable 367 * @path: path to usermode executable
336 * @argv: arg vector for process 368 * @argv: arg vector for process
337 * @envp: environment for process 369 * @envp: environment for process
338 * @gfp_mask: gfp mask for memory allocation 370 * @gfp_mask: gfp mask for memory allocation
339 * @init: an init function <<
340 * @cleanup: a cleanup function 371 * @cleanup: a cleanup function
>> 372 * @init: an init function
341 * @data: arbitrary context sensitive data 373 * @data: arbitrary context sensitive data
342 * 374 *
343 * Returns either %NULL on allocation failure, 375 * Returns either %NULL on allocation failure, or a subprocess_info
344 * structure. This should be passed to call_u 376 * structure. This should be passed to call_usermodehelper_exec to
345 * exec the process and free the structure. 377 * exec the process and free the structure.
346 * 378 *
347 * The init function is used to customize the 379 * The init function is used to customize the helper process prior to
348 * exec. A non-zero return code causes the pr 380 * exec. A non-zero return code causes the process to error out, exit,
349 * and return the failure to the calling proce 381 * and return the failure to the calling process
350 * 382 *
351 * The cleanup function is just before the sub !! 383 * The cleanup function is just before ethe subprocess_info is about to
352 * be freed. This can be used for freeing the 384 * be freed. This can be used for freeing the argv and envp. The
353 * Function must be runnable in either a proce 385 * Function must be runnable in either a process context or the
354 * context in which call_usermodehelper_exec i 386 * context in which call_usermodehelper_exec is called.
355 */ 387 */
356 struct subprocess_info *call_usermodehelper_se 388 struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv,
357 char **envp, gfp_t gfp_mask, 389 char **envp, gfp_t gfp_mask,
358 int (*init)(struct subprocess_ 390 int (*init)(struct subprocess_info *info, struct cred *new),
359 void (*cleanup)(struct subproc 391 void (*cleanup)(struct subprocess_info *info),
360 void *data) 392 void *data)
361 { 393 {
362 struct subprocess_info *sub_info; 394 struct subprocess_info *sub_info;
363 sub_info = kzalloc(sizeof(struct subpr 395 sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
364 if (!sub_info) 396 if (!sub_info)
365 goto out; 397 goto out;
366 398
367 INIT_WORK(&sub_info->work, call_usermo 399 INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
368 400
369 #ifdef CONFIG_STATIC_USERMODEHELPER 401 #ifdef CONFIG_STATIC_USERMODEHELPER
370 sub_info->path = CONFIG_STATIC_USERMOD 402 sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH;
371 #else 403 #else
372 sub_info->path = path; 404 sub_info->path = path;
373 #endif 405 #endif
374 sub_info->argv = argv; 406 sub_info->argv = argv;
375 sub_info->envp = envp; 407 sub_info->envp = envp;
376 408
377 sub_info->cleanup = cleanup; 409 sub_info->cleanup = cleanup;
378 sub_info->init = init; 410 sub_info->init = init;
379 sub_info->data = data; 411 sub_info->data = data;
380 out: 412 out:
381 return sub_info; 413 return sub_info;
382 } 414 }
383 EXPORT_SYMBOL(call_usermodehelper_setup); 415 EXPORT_SYMBOL(call_usermodehelper_setup);
384 416
>> 417 struct subprocess_info *call_usermodehelper_setup_file(struct file *file,
>> 418 int (*init)(struct subprocess_info *info, struct cred *new),
>> 419 void (*cleanup)(struct subprocess_info *info), void *data)
>> 420 {
>> 421 struct subprocess_info *sub_info;
>> 422 struct umh_info *info = data;
>> 423 const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper";
>> 424
>> 425 sub_info = kzalloc(sizeof(struct subprocess_info), GFP_KERNEL);
>> 426 if (!sub_info)
>> 427 return NULL;
>> 428
>> 429 sub_info->argv = argv_split(GFP_KERNEL, cmdline, NULL);
>> 430 if (!sub_info->argv) {
>> 431 kfree(sub_info);
>> 432 return NULL;
>> 433 }
>> 434
>> 435 INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
>> 436 sub_info->path = "none";
>> 437 sub_info->file = file;
>> 438 sub_info->init = init;
>> 439 sub_info->cleanup = cleanup;
>> 440 sub_info->data = data;
>> 441 return sub_info;
>> 442 }
>> 443
>> 444 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
>> 445 {
>> 446 struct umh_info *umh_info = info->data;
>> 447 struct file *from_umh[2];
>> 448 struct file *to_umh[2];
>> 449 int err;
>> 450
>> 451 /* create pipe to send data to umh */
>> 452 err = create_pipe_files(to_umh, 0);
>> 453 if (err)
>> 454 return err;
>> 455 err = replace_fd(0, to_umh[0], 0);
>> 456 fput(to_umh[0]);
>> 457 if (err < 0) {
>> 458 fput(to_umh[1]);
>> 459 return err;
>> 460 }
>> 461
>> 462 /* create pipe to receive data from umh */
>> 463 err = create_pipe_files(from_umh, 0);
>> 464 if (err) {
>> 465 fput(to_umh[1]);
>> 466 replace_fd(0, NULL, 0);
>> 467 return err;
>> 468 }
>> 469 err = replace_fd(1, from_umh[1], 0);
>> 470 fput(from_umh[1]);
>> 471 if (err < 0) {
>> 472 fput(to_umh[1]);
>> 473 replace_fd(0, NULL, 0);
>> 474 fput(from_umh[0]);
>> 475 return err;
>> 476 }
>> 477
>> 478 umh_info->pipe_to_umh = to_umh[1];
>> 479 umh_info->pipe_from_umh = from_umh[0];
>> 480 return 0;
>> 481 }
>> 482
>> 483 static void umh_clean_and_save_pid(struct subprocess_info *info)
>> 484 {
>> 485 struct umh_info *umh_info = info->data;
>> 486
>> 487 /* cleanup if umh_pipe_setup() was successful but exec failed */
>> 488 if (info->pid && info->retval) {
>> 489 fput(umh_info->pipe_to_umh);
>> 490 fput(umh_info->pipe_from_umh);
>> 491 }
>> 492
>> 493 argv_free(info->argv);
>> 494 umh_info->pid = info->pid;
>> 495 }
>> 496
>> 497 /**
>> 498 * fork_usermode_blob - fork a blob of bytes as a usermode process
>> 499 * @data: a blob of bytes that can be do_execv-ed as a file
>> 500 * @len: length of the blob
>> 501 * @info: information about usermode process (shouldn't be NULL)
>> 502 *
>> 503 * If info->cmdline is set it will be used as command line for the
>> 504 * user process, else "usermodehelper" is used.
>> 505 *
>> 506 * Returns either negative error or zero which indicates success
>> 507 * in executing a blob of bytes as a usermode process. In such
>> 508 * case 'struct umh_info *info' is populated with two pipes
>> 509 * and a pid of the process. The caller is responsible for health
>> 510 * check of the user process, killing it via pid, and closing the
>> 511 * pipes when user process is no longer needed.
>> 512 */
>> 513 int fork_usermode_blob(void *data, size_t len, struct umh_info *info)
>> 514 {
>> 515 struct subprocess_info *sub_info;
>> 516 struct file *file;
>> 517 ssize_t written;
>> 518 loff_t pos = 0;
>> 519 int err;
>> 520
>> 521 file = shmem_kernel_file_setup("", len, 0);
>> 522 if (IS_ERR(file))
>> 523 return PTR_ERR(file);
>> 524
>> 525 written = kernel_write(file, data, len, &pos);
>> 526 if (written != len) {
>> 527 err = written;
>> 528 if (err >= 0)
>> 529 err = -ENOMEM;
>> 530 goto out;
>> 531 }
>> 532
>> 533 err = -ENOMEM;
>> 534 sub_info = call_usermodehelper_setup_file(file, umh_pipe_setup,
>> 535 umh_clean_and_save_pid, info);
>> 536 if (!sub_info)
>> 537 goto out;
>> 538
>> 539 err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
>> 540 if (!err) {
>> 541 mutex_lock(&umh_list_lock);
>> 542 list_add(&info->list, &umh_list);
>> 543 mutex_unlock(&umh_list_lock);
>> 544 }
>> 545 out:
>> 546 fput(file);
>> 547 return err;
>> 548 }
>> 549 EXPORT_SYMBOL_GPL(fork_usermode_blob);
>> 550
385 /** 551 /**
386 * call_usermodehelper_exec - start a usermode 552 * call_usermodehelper_exec - start a usermode application
387 * @sub_info: information about the subprocess !! 553 * @sub_info: information about the subprocessa
388 * @wait: wait for the application to finish a 554 * @wait: wait for the application to finish and return status.
389 * when UMH_NO_WAIT don't wait at all, 555 * 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 556 * when the program couldn't be exec'ed. This makes it safe to call
391 * from interrupt context. 557 * from interrupt context.
392 * 558 *
393 * Runs a user-space application. The applica 559 * Runs a user-space application. The application is started
394 * asynchronously if wait is not set, and runs 560 * asynchronously if wait is not set, and runs as a child of system workqueues.
395 * (ie. it runs with full root capabilities an 561 * (ie. it runs with full root capabilities and optimized affinity).
396 * 562 *
397 * Note: successful return value does not guar 563 * Note: successful return value does not guarantee the helper was called at
398 * all. You can't rely on sub_info->{init,clea 564 * all. You can't rely on sub_info->{init,cleanup} being called even for
399 * UMH_WAIT_* wait modes as STATIC_USERMODEHEL 565 * UMH_WAIT_* wait modes as STATIC_USERMODEHELPER_PATH="" turns all helpers
400 * into a successful no-op. 566 * into a successful no-op.
401 */ 567 */
402 int call_usermodehelper_exec(struct subprocess 568 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
403 { 569 {
404 unsigned int state = TASK_UNINTERRUPTI <<
405 DECLARE_COMPLETION_ONSTACK(done); 570 DECLARE_COMPLETION_ONSTACK(done);
406 int retval = 0; 571 int retval = 0;
407 572
408 if (!sub_info->path) { 573 if (!sub_info->path) {
409 call_usermodehelper_freeinfo(s 574 call_usermodehelper_freeinfo(sub_info);
410 return -EINVAL; 575 return -EINVAL;
411 } 576 }
412 helper_lock(); 577 helper_lock();
413 if (usermodehelper_disabled) { 578 if (usermodehelper_disabled) {
414 retval = -EBUSY; 579 retval = -EBUSY;
415 goto out; 580 goto out;
416 } 581 }
417 582
418 /* 583 /*
419 * If there is no binary for us to cal 584 * If there is no binary for us to call, then just return and get out of
420 * here. This allows us to set STATIC 585 * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and
421 * disable all call_usermodehelper() c 586 * disable all call_usermodehelper() calls.
422 */ 587 */
423 if (strlen(sub_info->path) == 0) 588 if (strlen(sub_info->path) == 0)
424 goto out; 589 goto out;
425 590
426 /* 591 /*
427 * Set the completion pointer only if 592 * Set the completion pointer only if there is a waiter.
428 * This makes it possible to use umh_c 593 * This makes it possible to use umh_complete to free
429 * the data structure in case of UMH_N 594 * the data structure in case of UMH_NO_WAIT.
430 */ 595 */
431 sub_info->complete = (wait == UMH_NO_W 596 sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
432 sub_info->wait = wait; 597 sub_info->wait = wait;
433 598
434 queue_work(system_unbound_wq, &sub_inf 599 queue_work(system_unbound_wq, &sub_info->work);
435 if (wait == UMH_NO_WAIT) /* tas 600 if (wait == UMH_NO_WAIT) /* task has freed sub_info */
436 goto unlock; 601 goto unlock;
437 602
438 if (wait & UMH_FREEZABLE) <<
439 state |= TASK_FREEZABLE; <<
440 <<
441 if (wait & UMH_KILLABLE) { 603 if (wait & UMH_KILLABLE) {
442 retval = wait_for_completion_s !! 604 retval = wait_for_completion_killable(&done);
443 if (!retval) 605 if (!retval)
444 goto wait_done; 606 goto wait_done;
445 607
446 /* umh_complete() will see NUL 608 /* umh_complete() will see NULL and free sub_info */
447 if (xchg(&sub_info->complete, 609 if (xchg(&sub_info->complete, NULL))
448 goto unlock; 610 goto unlock;
449 !! 611 /* 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 } 612 }
458 wait_for_completion_state(&done, state <<
459 613
>> 614 wait_for_completion(&done);
460 wait_done: 615 wait_done:
461 retval = sub_info->retval; 616 retval = sub_info->retval;
462 out: 617 out:
463 call_usermodehelper_freeinfo(sub_info) 618 call_usermodehelper_freeinfo(sub_info);
464 unlock: 619 unlock:
465 helper_unlock(); 620 helper_unlock();
466 return retval; 621 return retval;
467 } 622 }
468 EXPORT_SYMBOL(call_usermodehelper_exec); 623 EXPORT_SYMBOL(call_usermodehelper_exec);
469 624
470 /** 625 /**
471 * call_usermodehelper() - prepare and start a 626 * call_usermodehelper() - prepare and start a usermode application
472 * @path: path to usermode executable 627 * @path: path to usermode executable
473 * @argv: arg vector for process 628 * @argv: arg vector for process
474 * @envp: environment for process 629 * @envp: environment for process
475 * @wait: wait for the application to finish a 630 * @wait: wait for the application to finish and return status.
476 * when UMH_NO_WAIT don't wait at all, 631 * 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 632 * when the program couldn't be exec'ed. This makes it safe to call
478 * from interrupt context. 633 * from interrupt context.
479 * 634 *
480 * This function is the equivalent to use call 635 * This function is the equivalent to use call_usermodehelper_setup() and
481 * call_usermodehelper_exec(). 636 * call_usermodehelper_exec().
482 */ 637 */
483 int call_usermodehelper(const char *path, char 638 int call_usermodehelper(const char *path, char **argv, char **envp, int wait)
484 { 639 {
485 struct subprocess_info *info; 640 struct subprocess_info *info;
486 gfp_t gfp_mask = (wait == UMH_NO_WAIT) 641 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
487 642
488 info = call_usermodehelper_setup(path, 643 info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
489 NULL, 644 NULL, NULL, NULL);
490 if (info == NULL) 645 if (info == NULL)
491 return -ENOMEM; 646 return -ENOMEM;
492 647
493 return call_usermodehelper_exec(info, 648 return call_usermodehelper_exec(info, wait);
494 } 649 }
495 EXPORT_SYMBOL(call_usermodehelper); 650 EXPORT_SYMBOL(call_usermodehelper);
496 651
497 #if defined(CONFIG_SYSCTL) !! 652 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 653 void *buffer, size_t *lenp, loff_t *ppos)
500 { 654 {
501 struct ctl_table t; 655 struct ctl_table t;
502 unsigned long cap_array[2]; !! 656 unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
503 kernel_cap_t new_cap, *cap; !! 657 kernel_cap_t new_cap;
504 int err; !! 658 int err, i;
505 659
506 if (write && (!capable(CAP_SETPCAP) || 660 if (write && (!capable(CAP_SETPCAP) ||
507 !capable(CAP_SYS_MODULE) 661 !capable(CAP_SYS_MODULE)))
508 return -EPERM; 662 return -EPERM;
509 663
510 /* 664 /*
511 * convert from the global kernel_cap_ 665 * convert from the global kernel_cap_t to the ulong array to print to
512 * userspace if this is a read. 666 * userspace if this is a read.
513 * <<
514 * Legacy format: capabilities are exp <<
515 */ 667 */
516 cap = table->data; <<
517 spin_lock(&umh_sysctl_lock); 668 spin_lock(&umh_sysctl_lock);
518 cap_array[0] = (u32) cap->val; !! 669 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
519 cap_array[1] = cap->val >> 32; !! 670 if (table->data == CAP_BSET)
>> 671 cap_array[i] = usermodehelper_bset.cap[i];
>> 672 else if (table->data == CAP_PI)
>> 673 cap_array[i] = usermodehelper_inheritable.cap[i];
>> 674 else
>> 675 BUG();
>> 676 }
520 spin_unlock(&umh_sysctl_lock); 677 spin_unlock(&umh_sysctl_lock);
521 678
522 t = *table; 679 t = *table;
523 t.data = &cap_array; 680 t.data = &cap_array;
524 681
525 /* 682 /*
526 * actually read or write and array of 683 * actually read or write and array of ulongs from userspace. Remember
527 * these are least significant 32 bits 684 * these are least significant 32 bits first
528 */ 685 */
529 err = proc_doulongvec_minmax(&t, write 686 err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
530 if (err < 0) 687 if (err < 0)
531 return err; 688 return err;
532 689
533 new_cap.val = (u32)cap_array[0]; !! 690 /*
534 new_cap.val += (u64)cap_array[1] << 32 !! 691 * convert from the sysctl array of ulongs to the kernel_cap_t
>> 692 * internal representation
>> 693 */
>> 694 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
>> 695 new_cap.cap[i] = cap_array[i];
535 696
536 /* 697 /*
537 * Drop everything not in the new_cap 698 * Drop everything not in the new_cap (but don't add things)
538 */ 699 */
539 if (write) { 700 if (write) {
540 spin_lock(&umh_sysctl_lock); 701 spin_lock(&umh_sysctl_lock);
541 *cap = cap_intersect(*cap, new !! 702 if (table->data == CAP_BSET)
>> 703 usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
>> 704 if (table->data == CAP_PI)
>> 705 usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
542 spin_unlock(&umh_sysctl_lock); 706 spin_unlock(&umh_sysctl_lock);
543 } 707 }
544 708
545 return 0; 709 return 0;
546 } 710 }
547 711
548 static struct ctl_table usermodehelper_table[] !! 712 void __exit_umh(struct task_struct *tsk)
>> 713 {
>> 714 struct umh_info *info;
>> 715 pid_t pid = tsk->pid;
>> 716
>> 717 mutex_lock(&umh_list_lock);
>> 718 list_for_each_entry(info, &umh_list, list) {
>> 719 if (info->pid == pid) {
>> 720 list_del(&info->list);
>> 721 mutex_unlock(&umh_list_lock);
>> 722 goto out;
>> 723 }
>> 724 }
>> 725 mutex_unlock(&umh_list_lock);
>> 726 return;
>> 727 out:
>> 728 if (info->cleanup)
>> 729 info->cleanup(info);
>> 730 }
>> 731
>> 732 struct ctl_table usermodehelper_table[] = {
549 { 733 {
550 .procname = "bset", 734 .procname = "bset",
551 .data = &usermodehel !! 735 .data = CAP_BSET,
552 .maxlen = 2 * sizeof(u !! 736 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
553 .mode = 0600, 737 .mode = 0600,
554 .proc_handler = proc_cap_han 738 .proc_handler = proc_cap_handler,
555 }, 739 },
556 { 740 {
557 .procname = "inheritable 741 .procname = "inheritable",
558 .data = &usermodehel !! 742 .data = CAP_PI,
559 .maxlen = 2 * sizeof(u !! 743 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
560 .mode = 0600, 744 .mode = 0600,
561 .proc_handler = proc_cap_han 745 .proc_handler = proc_cap_handler,
562 }, 746 },
>> 747 { }
563 }; 748 };
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 */ <<
572 749
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