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> !! 28 #include <linux/shmem_fs.h>
31 #include <linux/freezer.h> !! 29 #include <linux/pipe_fs_i.h>
32 30
33 #include <trace/events/module.h> 31 #include <trace/events/module.h>
34 32
>> 33 #define CAP_BSET (void *)1
>> 34 #define CAP_PI (void *)2
>> 35
35 static kernel_cap_t usermodehelper_bset = CAP_ 36 static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
36 static kernel_cap_t usermodehelper_inheritable 37 static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
37 static DEFINE_SPINLOCK(umh_sysctl_lock); 38 static DEFINE_SPINLOCK(umh_sysctl_lock);
38 static DECLARE_RWSEM(umhelper_sem); 39 static DECLARE_RWSEM(umhelper_sem);
>> 40 static LIST_HEAD(umh_list);
>> 41 static DEFINE_MUTEX(umh_list_lock);
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 <<
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 78 * Our parent (unbound workqueue) runs with elevated scheduling
84 * priority. Avoid propagating that in 79 * priority. Avoid propagating that into the userspace child.
85 */ 80 */
86 set_user_nice(current, 0); 81 set_user_nice(current, 0);
87 82
88 retval = -ENOMEM; 83 retval = -ENOMEM;
89 new = prepare_kernel_cred(current); 84 new = prepare_kernel_cred(current);
90 if (!new) 85 if (!new)
91 goto out; 86 goto out;
92 87
93 spin_lock(&umh_sysctl_lock); 88 spin_lock(&umh_sysctl_lock);
94 new->cap_bset = cap_intersect(usermode 89 new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
95 new->cap_inheritable = cap_intersect(u 90 new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
96 n 91 new->cap_inheritable);
97 spin_unlock(&umh_sysctl_lock); 92 spin_unlock(&umh_sysctl_lock);
98 93
99 if (sub_info->init) { 94 if (sub_info->init) {
100 retval = sub_info->init(sub_in 95 retval = sub_info->init(sub_info, new);
101 if (retval) { 96 if (retval) {
102 abort_creds(new); 97 abort_creds(new);
103 goto out; 98 goto out;
104 } 99 }
105 } 100 }
106 101
107 commit_creds(new); 102 commit_creds(new);
108 103
109 wait_for_initramfs(); !! 104 sub_info->pid = task_pid_nr(current);
110 retval = kernel_execve(sub_info->path, !! 105 if (sub_info->file) {
111 (const char *co !! 106 retval = do_execve_file(sub_info->file,
112 (const char *co !! 107 sub_info->argv, sub_info->envp);
>> 108 if (!retval)
>> 109 current->flags |= PF_UMH;
>> 110 } else
>> 111 retval = do_execve(getname_kernel(sub_info->path),
>> 112 (const char __user *const __user *)sub_info->argv,
>> 113 (const char __user *const __user *)sub_info->envp);
113 out: 114 out:
114 sub_info->retval = retval; 115 sub_info->retval = retval;
115 /* 116 /*
116 * call_usermodehelper_exec_sync() wil 117 * call_usermodehelper_exec_sync() will call umh_complete
117 * if UHM_WAIT_PROC. 118 * if UHM_WAIT_PROC.
118 */ 119 */
119 if (!(sub_info->wait & UMH_WAIT_PROC)) 120 if (!(sub_info->wait & UMH_WAIT_PROC))
120 umh_complete(sub_info); 121 umh_complete(sub_info);
121 if (!retval) 122 if (!retval)
122 return 0; 123 return 0;
123 do_exit(0); 124 do_exit(0);
124 } 125 }
125 126
126 /* Handles UMH_WAIT_PROC. */ 127 /* Handles UMH_WAIT_PROC. */
127 static void call_usermodehelper_exec_sync(stru 128 static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
128 { 129 {
129 pid_t pid; 130 pid_t pid;
130 131
131 /* If SIGCLD is ignored do_wait won't !! 132 /* If SIGCLD is ignored kernel_wait4 won't populate the status. */
132 kernel_sigaction(SIGCHLD, SIG_DFL); 133 kernel_sigaction(SIGCHLD, SIG_DFL);
133 pid = user_mode_thread(call_usermodehe !! 134 pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
134 if (pid < 0) !! 135 if (pid < 0) {
135 sub_info->retval = pid; 136 sub_info->retval = pid;
136 else !! 137 } else {
137 kernel_wait(pid, &sub_info->re !! 138 int ret = -ECHILD;
>> 139 /*
>> 140 * Normally it is bogus to call wait4() from in-kernel because
>> 141 * wait4() wants to write the exit code to a userspace address.
>> 142 * But call_usermodehelper_exec_sync() always runs as kernel
>> 143 * thread (workqueue) and put_user() to a kernel address works
>> 144 * OK for kernel threads, due to their having an mm_segment_t
>> 145 * which spans the entire address space.
>> 146 *
>> 147 * Thus the __user pointer cast is valid here.
>> 148 */
>> 149 kernel_wait4(pid, (int __user *)&ret, 0, NULL);
>> 150
>> 151 /*
>> 152 * If ret is 0, either call_usermodehelper_exec_async failed and
>> 153 * the real error code is already in sub_info->retval or
>> 154 * sub_info->retval is 0 anyway, so don't mess with it then.
>> 155 */
>> 156 if (ret)
>> 157 sub_info->retval = ret;
>> 158 }
138 159
139 /* Restore default kernel sig handler 160 /* Restore default kernel sig handler */
140 kernel_sigaction(SIGCHLD, SIG_IGN); 161 kernel_sigaction(SIGCHLD, SIG_IGN);
>> 162
141 umh_complete(sub_info); 163 umh_complete(sub_info);
142 } 164 }
143 165
144 /* 166 /*
145 * We need to create the usermodehelper kernel 167 * We need to create the usermodehelper kernel thread from a task that is affine
146 * to an optimized set of CPUs (or nohz housek 168 * to an optimized set of CPUs (or nohz housekeeping ones) such that they
147 * inherit a widest affinity irrespective of c 169 * inherit a widest affinity irrespective of call_usermodehelper() callers with
148 * possibly reduced affinity (eg: per-cpu work 170 * possibly reduced affinity (eg: per-cpu workqueues). We don't want
149 * usermodehelper targets to contend a busy CP 171 * usermodehelper targets to contend a busy CPU.
150 * 172 *
151 * Unbound workqueues provide such wide affini 173 * Unbound workqueues provide such wide affinity and allow to block on
152 * UMH_WAIT_PROC requests without blocking pen 174 * UMH_WAIT_PROC requests without blocking pending request (up to some limit).
153 * 175 *
154 * Besides, workqueues provide the privilege l 176 * Besides, workqueues provide the privilege level that caller might not have
155 * to perform the usermodehelper request. 177 * to perform the usermodehelper request.
156 * 178 *
157 */ 179 */
158 static void call_usermodehelper_exec_work(stru 180 static void call_usermodehelper_exec_work(struct work_struct *work)
159 { 181 {
160 struct subprocess_info *sub_info = 182 struct subprocess_info *sub_info =
161 container_of(work, struct subp 183 container_of(work, struct subprocess_info, work);
162 184
163 if (sub_info->wait & UMH_WAIT_PROC) { 185 if (sub_info->wait & UMH_WAIT_PROC) {
164 call_usermodehelper_exec_sync( 186 call_usermodehelper_exec_sync(sub_info);
165 } else { 187 } else {
166 pid_t pid; 188 pid_t pid;
167 /* 189 /*
168 * Use CLONE_PARENT to reparen 190 * Use CLONE_PARENT to reparent it to kthreadd; we do not
169 * want to pollute current->ch 191 * want to pollute current->children, and we need a parent
170 * that always ignores SIGCHLD 192 * that always ignores SIGCHLD to ensure auto-reaping.
171 */ 193 */
172 pid = user_mode_thread(call_us !! 194 pid = kernel_thread(call_usermodehelper_exec_async, sub_info,
173 CLONE_P !! 195 CLONE_PARENT | SIGCHLD);
174 if (pid < 0) { 196 if (pid < 0) {
175 sub_info->retval = pid 197 sub_info->retval = pid;
176 umh_complete(sub_info) 198 umh_complete(sub_info);
177 } 199 }
178 } 200 }
179 } 201 }
180 202
181 /* 203 /*
182 * If set, call_usermodehelper_exec() will exi 204 * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
183 * (used for preventing user land processes fr 205 * (used for preventing user land processes from being created after the user
184 * land has been frozen during a system-wide h 206 * land has been frozen during a system-wide hibernation or suspend operation).
185 * Should always be manipulated under umhelper 207 * Should always be manipulated under umhelper_sem acquired for write.
186 */ 208 */
187 static enum umh_disable_depth usermodehelper_d 209 static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
188 210
189 /* Number of helpers running */ 211 /* Number of helpers running */
190 static atomic_t running_helpers = ATOMIC_INIT( 212 static atomic_t running_helpers = ATOMIC_INIT(0);
191 213
192 /* 214 /*
193 * Wait queue head used by usermodehelper_disa 215 * Wait queue head used by usermodehelper_disable() to wait for all running
194 * helpers to finish. 216 * helpers to finish.
195 */ 217 */
196 static DECLARE_WAIT_QUEUE_HEAD(running_helpers 218 static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
197 219
198 /* 220 /*
199 * Used by usermodehelper_read_lock_wait() to 221 * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
200 * to become 'false'. 222 * to become 'false'.
201 */ 223 */
202 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_ 224 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
203 225
204 /* 226 /*
205 * Time to wait for running_helpers to become 227 * Time to wait for running_helpers to become zero before the setting of
206 * usermodehelper_disabled in usermodehelper_d 228 * usermodehelper_disabled in usermodehelper_disable() fails
207 */ 229 */
208 #define RUNNING_HELPERS_TIMEOUT (5 * HZ) 230 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
209 231
210 int usermodehelper_read_trylock(void) 232 int usermodehelper_read_trylock(void)
211 { 233 {
212 DEFINE_WAIT(wait); 234 DEFINE_WAIT(wait);
213 int ret = 0; 235 int ret = 0;
214 236
215 down_read(&umhelper_sem); 237 down_read(&umhelper_sem);
216 for (;;) { 238 for (;;) {
217 prepare_to_wait(&usermodehelpe 239 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
218 TASK_INTERRUPT 240 TASK_INTERRUPTIBLE);
219 if (!usermodehelper_disabled) 241 if (!usermodehelper_disabled)
220 break; 242 break;
221 243
222 if (usermodehelper_disabled == 244 if (usermodehelper_disabled == UMH_DISABLED)
223 ret = -EAGAIN; 245 ret = -EAGAIN;
224 246
225 up_read(&umhelper_sem); 247 up_read(&umhelper_sem);
226 248
227 if (ret) 249 if (ret)
228 break; 250 break;
229 251
230 schedule(); 252 schedule();
231 try_to_freeze(); 253 try_to_freeze();
232 254
233 down_read(&umhelper_sem); 255 down_read(&umhelper_sem);
234 } 256 }
235 finish_wait(&usermodehelper_disabled_w 257 finish_wait(&usermodehelper_disabled_waitq, &wait);
236 return ret; 258 return ret;
237 } 259 }
238 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock) 260 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
239 261
240 long usermodehelper_read_lock_wait(long timeou 262 long usermodehelper_read_lock_wait(long timeout)
241 { 263 {
242 DEFINE_WAIT(wait); 264 DEFINE_WAIT(wait);
243 265
244 if (timeout < 0) 266 if (timeout < 0)
245 return -EINVAL; 267 return -EINVAL;
246 268
247 down_read(&umhelper_sem); 269 down_read(&umhelper_sem);
248 for (;;) { 270 for (;;) {
249 prepare_to_wait(&usermodehelpe 271 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
250 TASK_UNINTERRU 272 TASK_UNINTERRUPTIBLE);
251 if (!usermodehelper_disabled) 273 if (!usermodehelper_disabled)
252 break; 274 break;
253 275
254 up_read(&umhelper_sem); 276 up_read(&umhelper_sem);
255 277
256 timeout = schedule_timeout(tim 278 timeout = schedule_timeout(timeout);
257 if (!timeout) 279 if (!timeout)
258 break; 280 break;
259 281
260 down_read(&umhelper_sem); 282 down_read(&umhelper_sem);
261 } 283 }
262 finish_wait(&usermodehelper_disabled_w 284 finish_wait(&usermodehelper_disabled_waitq, &wait);
263 return timeout; 285 return timeout;
264 } 286 }
265 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wai 287 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
266 288
267 void usermodehelper_read_unlock(void) 289 void usermodehelper_read_unlock(void)
268 { 290 {
269 up_read(&umhelper_sem); 291 up_read(&umhelper_sem);
270 } 292 }
271 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock); 293 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
272 294
273 /** 295 /**
274 * __usermodehelper_set_disable_depth - Modify 296 * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
275 * @depth: New value to assign to usermodehelp 297 * @depth: New value to assign to usermodehelper_disabled.
276 * 298 *
277 * Change the value of usermodehelper_disabled 299 * Change the value of usermodehelper_disabled (under umhelper_sem locked for
278 * writing) and wakeup tasks waiting for it to 300 * writing) and wakeup tasks waiting for it to change.
279 */ 301 */
280 void __usermodehelper_set_disable_depth(enum u 302 void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
281 { 303 {
282 down_write(&umhelper_sem); 304 down_write(&umhelper_sem);
283 usermodehelper_disabled = depth; 305 usermodehelper_disabled = depth;
284 wake_up(&usermodehelper_disabled_waitq 306 wake_up(&usermodehelper_disabled_waitq);
285 up_write(&umhelper_sem); 307 up_write(&umhelper_sem);
286 } 308 }
287 309
288 /** 310 /**
289 * __usermodehelper_disable - Prevent new help 311 * __usermodehelper_disable - Prevent new helpers from being started.
290 * @depth: New value to assign to usermodehelp 312 * @depth: New value to assign to usermodehelper_disabled.
291 * 313 *
292 * Set usermodehelper_disabled to @depth and w 314 * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
293 */ 315 */
294 int __usermodehelper_disable(enum umh_disable_ 316 int __usermodehelper_disable(enum umh_disable_depth depth)
295 { 317 {
296 long retval; 318 long retval;
297 319
298 if (!depth) 320 if (!depth)
299 return -EINVAL; 321 return -EINVAL;
300 322
301 down_write(&umhelper_sem); 323 down_write(&umhelper_sem);
302 usermodehelper_disabled = depth; 324 usermodehelper_disabled = depth;
303 up_write(&umhelper_sem); 325 up_write(&umhelper_sem);
304 326
305 /* 327 /*
306 * From now on call_usermodehelper_exe 328 * From now on call_usermodehelper_exec() won't start any new
307 * helpers, so it is sufficient if run 329 * helpers, so it is sufficient if running_helpers turns out to
308 * be zero at one point (it may be inc 330 * be zero at one point (it may be increased later, but that
309 * doesn't matter). 331 * doesn't matter).
310 */ 332 */
311 retval = wait_event_timeout(running_he 333 retval = wait_event_timeout(running_helpers_waitq,
312 atomic 334 atomic_read(&running_helpers) == 0,
313 RUNNIN 335 RUNNING_HELPERS_TIMEOUT);
314 if (retval) 336 if (retval)
315 return 0; 337 return 0;
316 338
317 __usermodehelper_set_disable_depth(UMH 339 __usermodehelper_set_disable_depth(UMH_ENABLED);
318 return -EAGAIN; 340 return -EAGAIN;
319 } 341 }
320 342
321 static void helper_lock(void) 343 static void helper_lock(void)
322 { 344 {
323 atomic_inc(&running_helpers); 345 atomic_inc(&running_helpers);
324 smp_mb__after_atomic(); 346 smp_mb__after_atomic();
325 } 347 }
326 348
327 static void helper_unlock(void) 349 static void helper_unlock(void)
328 { 350 {
329 if (atomic_dec_and_test(&running_helpe 351 if (atomic_dec_and_test(&running_helpers))
330 wake_up(&running_helpers_waitq 352 wake_up(&running_helpers_waitq);
331 } 353 }
332 354
333 /** 355 /**
334 * call_usermodehelper_setup - prepare to call 356 * call_usermodehelper_setup - prepare to call a usermode helper
335 * @path: path to usermode executable 357 * @path: path to usermode executable
336 * @argv: arg vector for process 358 * @argv: arg vector for process
337 * @envp: environment for process 359 * @envp: environment for process
338 * @gfp_mask: gfp mask for memory allocation 360 * @gfp_mask: gfp mask for memory allocation
339 * @init: an init function <<
340 * @cleanup: a cleanup function 361 * @cleanup: a cleanup function
>> 362 * @init: an init function
341 * @data: arbitrary context sensitive data 363 * @data: arbitrary context sensitive data
342 * 364 *
343 * Returns either %NULL on allocation failure, 365 * Returns either %NULL on allocation failure, or a subprocess_info
344 * structure. This should be passed to call_u 366 * structure. This should be passed to call_usermodehelper_exec to
345 * exec the process and free the structure. 367 * exec the process and free the structure.
346 * 368 *
347 * The init function is used to customize the 369 * The init function is used to customize the helper process prior to
348 * exec. A non-zero return code causes the pr 370 * exec. A non-zero return code causes the process to error out, exit,
349 * and return the failure to the calling proce 371 * and return the failure to the calling process
350 * 372 *
351 * The cleanup function is just before the sub !! 373 * The cleanup function is just before ethe subprocess_info is about to
352 * be freed. This can be used for freeing the 374 * be freed. This can be used for freeing the argv and envp. The
353 * Function must be runnable in either a proce 375 * Function must be runnable in either a process context or the
354 * context in which call_usermodehelper_exec i 376 * context in which call_usermodehelper_exec is called.
355 */ 377 */
356 struct subprocess_info *call_usermodehelper_se 378 struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv,
357 char **envp, gfp_t gfp_mask, 379 char **envp, gfp_t gfp_mask,
358 int (*init)(struct subprocess_ 380 int (*init)(struct subprocess_info *info, struct cred *new),
359 void (*cleanup)(struct subproc 381 void (*cleanup)(struct subprocess_info *info),
360 void *data) 382 void *data)
361 { 383 {
362 struct subprocess_info *sub_info; 384 struct subprocess_info *sub_info;
363 sub_info = kzalloc(sizeof(struct subpr 385 sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
364 if (!sub_info) 386 if (!sub_info)
365 goto out; 387 goto out;
366 388
367 INIT_WORK(&sub_info->work, call_usermo 389 INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
368 390
369 #ifdef CONFIG_STATIC_USERMODEHELPER 391 #ifdef CONFIG_STATIC_USERMODEHELPER
370 sub_info->path = CONFIG_STATIC_USERMOD 392 sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH;
371 #else 393 #else
372 sub_info->path = path; 394 sub_info->path = path;
373 #endif 395 #endif
374 sub_info->argv = argv; 396 sub_info->argv = argv;
375 sub_info->envp = envp; 397 sub_info->envp = envp;
376 398
377 sub_info->cleanup = cleanup; 399 sub_info->cleanup = cleanup;
378 sub_info->init = init; 400 sub_info->init = init;
379 sub_info->data = data; 401 sub_info->data = data;
380 out: 402 out:
381 return sub_info; 403 return sub_info;
382 } 404 }
383 EXPORT_SYMBOL(call_usermodehelper_setup); 405 EXPORT_SYMBOL(call_usermodehelper_setup);
384 406
>> 407 struct subprocess_info *call_usermodehelper_setup_file(struct file *file,
>> 408 int (*init)(struct subprocess_info *info, struct cred *new),
>> 409 void (*cleanup)(struct subprocess_info *info), void *data)
>> 410 {
>> 411 struct subprocess_info *sub_info;
>> 412 struct umh_info *info = data;
>> 413 const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper";
>> 414
>> 415 sub_info = kzalloc(sizeof(struct subprocess_info), GFP_KERNEL);
>> 416 if (!sub_info)
>> 417 return NULL;
>> 418
>> 419 sub_info->argv = argv_split(GFP_KERNEL, cmdline, NULL);
>> 420 if (!sub_info->argv) {
>> 421 kfree(sub_info);
>> 422 return NULL;
>> 423 }
>> 424
>> 425 INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
>> 426 sub_info->path = "none";
>> 427 sub_info->file = file;
>> 428 sub_info->init = init;
>> 429 sub_info->cleanup = cleanup;
>> 430 sub_info->data = data;
>> 431 return sub_info;
>> 432 }
>> 433
>> 434 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
>> 435 {
>> 436 struct umh_info *umh_info = info->data;
>> 437 struct file *from_umh[2];
>> 438 struct file *to_umh[2];
>> 439 int err;
>> 440
>> 441 /* create pipe to send data to umh */
>> 442 err = create_pipe_files(to_umh, 0);
>> 443 if (err)
>> 444 return err;
>> 445 err = replace_fd(0, to_umh[0], 0);
>> 446 fput(to_umh[0]);
>> 447 if (err < 0) {
>> 448 fput(to_umh[1]);
>> 449 return err;
>> 450 }
>> 451
>> 452 /* create pipe to receive data from umh */
>> 453 err = create_pipe_files(from_umh, 0);
>> 454 if (err) {
>> 455 fput(to_umh[1]);
>> 456 replace_fd(0, NULL, 0);
>> 457 return err;
>> 458 }
>> 459 err = replace_fd(1, from_umh[1], 0);
>> 460 fput(from_umh[1]);
>> 461 if (err < 0) {
>> 462 fput(to_umh[1]);
>> 463 replace_fd(0, NULL, 0);
>> 464 fput(from_umh[0]);
>> 465 return err;
>> 466 }
>> 467
>> 468 umh_info->pipe_to_umh = to_umh[1];
>> 469 umh_info->pipe_from_umh = from_umh[0];
>> 470 return 0;
>> 471 }
>> 472
>> 473 static void umh_clean_and_save_pid(struct subprocess_info *info)
>> 474 {
>> 475 struct umh_info *umh_info = info->data;
>> 476
>> 477 argv_free(info->argv);
>> 478 umh_info->pid = info->pid;
>> 479 }
>> 480
>> 481 /**
>> 482 * fork_usermode_blob - fork a blob of bytes as a usermode process
>> 483 * @data: a blob of bytes that can be do_execv-ed as a file
>> 484 * @len: length of the blob
>> 485 * @info: information about usermode process (shouldn't be NULL)
>> 486 *
>> 487 * If info->cmdline is set it will be used as command line for the
>> 488 * user process, else "usermodehelper" is used.
>> 489 *
>> 490 * Returns either negative error or zero which indicates success
>> 491 * in executing a blob of bytes as a usermode process. In such
>> 492 * case 'struct umh_info *info' is populated with two pipes
>> 493 * and a pid of the process. The caller is responsible for health
>> 494 * check of the user process, killing it via pid, and closing the
>> 495 * pipes when user process is no longer needed.
>> 496 */
>> 497 int fork_usermode_blob(void *data, size_t len, struct umh_info *info)
>> 498 {
>> 499 struct subprocess_info *sub_info;
>> 500 struct file *file;
>> 501 ssize_t written;
>> 502 loff_t pos = 0;
>> 503 int err;
>> 504
>> 505 file = shmem_kernel_file_setup("", len, 0);
>> 506 if (IS_ERR(file))
>> 507 return PTR_ERR(file);
>> 508
>> 509 written = kernel_write(file, data, len, &pos);
>> 510 if (written != len) {
>> 511 err = written;
>> 512 if (err >= 0)
>> 513 err = -ENOMEM;
>> 514 goto out;
>> 515 }
>> 516
>> 517 err = -ENOMEM;
>> 518 sub_info = call_usermodehelper_setup_file(file, umh_pipe_setup,
>> 519 umh_clean_and_save_pid, info);
>> 520 if (!sub_info)
>> 521 goto out;
>> 522
>> 523 err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
>> 524 if (!err) {
>> 525 mutex_lock(&umh_list_lock);
>> 526 list_add(&info->list, &umh_list);
>> 527 mutex_unlock(&umh_list_lock);
>> 528 }
>> 529 out:
>> 530 fput(file);
>> 531 return err;
>> 532 }
>> 533 EXPORT_SYMBOL_GPL(fork_usermode_blob);
>> 534
385 /** 535 /**
386 * call_usermodehelper_exec - start a usermode 536 * call_usermodehelper_exec - start a usermode application
387 * @sub_info: information about the subprocess !! 537 * @sub_info: information about the subprocessa
388 * @wait: wait for the application to finish a 538 * @wait: wait for the application to finish and return status.
389 * when UMH_NO_WAIT don't wait at all, 539 * 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 540 * when the program couldn't be exec'ed. This makes it safe to call
391 * from interrupt context. 541 * from interrupt context.
392 * 542 *
393 * Runs a user-space application. The applica 543 * Runs a user-space application. The application is started
394 * asynchronously if wait is not set, and runs 544 * asynchronously if wait is not set, and runs as a child of system workqueues.
395 * (ie. it runs with full root capabilities an 545 * (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 */ 546 */
402 int call_usermodehelper_exec(struct subprocess 547 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
403 { 548 {
404 unsigned int state = TASK_UNINTERRUPTI <<
405 DECLARE_COMPLETION_ONSTACK(done); 549 DECLARE_COMPLETION_ONSTACK(done);
406 int retval = 0; 550 int retval = 0;
407 551
408 if (!sub_info->path) { 552 if (!sub_info->path) {
409 call_usermodehelper_freeinfo(s 553 call_usermodehelper_freeinfo(sub_info);
410 return -EINVAL; 554 return -EINVAL;
411 } 555 }
412 helper_lock(); 556 helper_lock();
413 if (usermodehelper_disabled) { 557 if (usermodehelper_disabled) {
414 retval = -EBUSY; 558 retval = -EBUSY;
415 goto out; 559 goto out;
416 } 560 }
417 561
418 /* 562 /*
419 * If there is no binary for us to cal 563 * If there is no binary for us to call, then just return and get out of
420 * here. This allows us to set STATIC 564 * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and
421 * disable all call_usermodehelper() c 565 * disable all call_usermodehelper() calls.
422 */ 566 */
423 if (strlen(sub_info->path) == 0) 567 if (strlen(sub_info->path) == 0)
424 goto out; 568 goto out;
425 569
426 /* 570 /*
427 * Set the completion pointer only if 571 * Set the completion pointer only if there is a waiter.
428 * This makes it possible to use umh_c 572 * This makes it possible to use umh_complete to free
429 * the data structure in case of UMH_N 573 * the data structure in case of UMH_NO_WAIT.
430 */ 574 */
431 sub_info->complete = (wait == UMH_NO_W 575 sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
432 sub_info->wait = wait; 576 sub_info->wait = wait;
433 577
434 queue_work(system_unbound_wq, &sub_inf 578 queue_work(system_unbound_wq, &sub_info->work);
435 if (wait == UMH_NO_WAIT) /* tas 579 if (wait == UMH_NO_WAIT) /* task has freed sub_info */
436 goto unlock; 580 goto unlock;
437 581
438 if (wait & UMH_FREEZABLE) <<
439 state |= TASK_FREEZABLE; <<
440 <<
441 if (wait & UMH_KILLABLE) { 582 if (wait & UMH_KILLABLE) {
442 retval = wait_for_completion_s !! 583 retval = wait_for_completion_killable(&done);
443 if (!retval) 584 if (!retval)
444 goto wait_done; 585 goto wait_done;
445 586
446 /* umh_complete() will see NUL 587 /* umh_complete() will see NULL and free sub_info */
447 if (xchg(&sub_info->complete, 588 if (xchg(&sub_info->complete, NULL))
448 goto unlock; 589 goto unlock;
449 !! 590 /* 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 } 591 }
458 wait_for_completion_state(&done, state <<
459 592
>> 593 wait_for_completion(&done);
460 wait_done: 594 wait_done:
461 retval = sub_info->retval; 595 retval = sub_info->retval;
462 out: 596 out:
463 call_usermodehelper_freeinfo(sub_info) 597 call_usermodehelper_freeinfo(sub_info);
464 unlock: 598 unlock:
465 helper_unlock(); 599 helper_unlock();
466 return retval; 600 return retval;
467 } 601 }
468 EXPORT_SYMBOL(call_usermodehelper_exec); 602 EXPORT_SYMBOL(call_usermodehelper_exec);
469 603
470 /** 604 /**
471 * call_usermodehelper() - prepare and start a 605 * call_usermodehelper() - prepare and start a usermode application
472 * @path: path to usermode executable 606 * @path: path to usermode executable
473 * @argv: arg vector for process 607 * @argv: arg vector for process
474 * @envp: environment for process 608 * @envp: environment for process
475 * @wait: wait for the application to finish a 609 * @wait: wait for the application to finish and return status.
476 * when UMH_NO_WAIT don't wait at all, 610 * 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 611 * when the program couldn't be exec'ed. This makes it safe to call
478 * from interrupt context. 612 * from interrupt context.
479 * 613 *
480 * This function is the equivalent to use call 614 * This function is the equivalent to use call_usermodehelper_setup() and
481 * call_usermodehelper_exec(). 615 * call_usermodehelper_exec().
482 */ 616 */
483 int call_usermodehelper(const char *path, char 617 int call_usermodehelper(const char *path, char **argv, char **envp, int wait)
484 { 618 {
485 struct subprocess_info *info; 619 struct subprocess_info *info;
486 gfp_t gfp_mask = (wait == UMH_NO_WAIT) 620 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
487 621
488 info = call_usermodehelper_setup(path, 622 info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
489 NULL, 623 NULL, NULL, NULL);
490 if (info == NULL) 624 if (info == NULL)
491 return -ENOMEM; 625 return -ENOMEM;
492 626
493 return call_usermodehelper_exec(info, 627 return call_usermodehelper_exec(info, wait);
494 } 628 }
495 EXPORT_SYMBOL(call_usermodehelper); 629 EXPORT_SYMBOL(call_usermodehelper);
496 630
497 #if defined(CONFIG_SYSCTL) !! 631 static int proc_cap_handler(struct ctl_table *table, int write,
498 static int proc_cap_handler(const struct ctl_t !! 632 void __user *buffer, size_t *lenp, loff_t *ppos)
499 void *buffer, size_t <<
500 { 633 {
501 struct ctl_table t; 634 struct ctl_table t;
502 unsigned long cap_array[2]; !! 635 unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
503 kernel_cap_t new_cap, *cap; !! 636 kernel_cap_t new_cap;
504 int err; !! 637 int err, i;
505 638
506 if (write && (!capable(CAP_SETPCAP) || 639 if (write && (!capable(CAP_SETPCAP) ||
507 !capable(CAP_SYS_MODULE) 640 !capable(CAP_SYS_MODULE)))
508 return -EPERM; 641 return -EPERM;
509 642
510 /* 643 /*
511 * convert from the global kernel_cap_ 644 * convert from the global kernel_cap_t to the ulong array to print to
512 * userspace if this is a read. 645 * userspace if this is a read.
513 * <<
514 * Legacy format: capabilities are exp <<
515 */ 646 */
516 cap = table->data; <<
517 spin_lock(&umh_sysctl_lock); 647 spin_lock(&umh_sysctl_lock);
518 cap_array[0] = (u32) cap->val; !! 648 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
519 cap_array[1] = cap->val >> 32; !! 649 if (table->data == CAP_BSET)
>> 650 cap_array[i] = usermodehelper_bset.cap[i];
>> 651 else if (table->data == CAP_PI)
>> 652 cap_array[i] = usermodehelper_inheritable.cap[i];
>> 653 else
>> 654 BUG();
>> 655 }
520 spin_unlock(&umh_sysctl_lock); 656 spin_unlock(&umh_sysctl_lock);
521 657
522 t = *table; 658 t = *table;
523 t.data = &cap_array; 659 t.data = &cap_array;
524 660
525 /* 661 /*
526 * actually read or write and array of 662 * actually read or write and array of ulongs from userspace. Remember
527 * these are least significant 32 bits 663 * these are least significant 32 bits first
528 */ 664 */
529 err = proc_doulongvec_minmax(&t, write 665 err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
530 if (err < 0) 666 if (err < 0)
531 return err; 667 return err;
532 668
533 new_cap.val = (u32)cap_array[0]; !! 669 /*
534 new_cap.val += (u64)cap_array[1] << 32 !! 670 * convert from the sysctl array of ulongs to the kernel_cap_t
>> 671 * internal representation
>> 672 */
>> 673 for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
>> 674 new_cap.cap[i] = cap_array[i];
535 675
536 /* 676 /*
537 * Drop everything not in the new_cap 677 * Drop everything not in the new_cap (but don't add things)
538 */ 678 */
539 if (write) { 679 if (write) {
540 spin_lock(&umh_sysctl_lock); 680 spin_lock(&umh_sysctl_lock);
541 *cap = cap_intersect(*cap, new !! 681 if (table->data == CAP_BSET)
>> 682 usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
>> 683 if (table->data == CAP_PI)
>> 684 usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
542 spin_unlock(&umh_sysctl_lock); 685 spin_unlock(&umh_sysctl_lock);
543 } 686 }
544 687
545 return 0; 688 return 0;
546 } 689 }
547 690
548 static struct ctl_table usermodehelper_table[] !! 691 void __exit_umh(struct task_struct *tsk)
>> 692 {
>> 693 struct umh_info *info;
>> 694 pid_t pid = tsk->pid;
>> 695
>> 696 mutex_lock(&umh_list_lock);
>> 697 list_for_each_entry(info, &umh_list, list) {
>> 698 if (info->pid == pid) {
>> 699 list_del(&info->list);
>> 700 mutex_unlock(&umh_list_lock);
>> 701 goto out;
>> 702 }
>> 703 }
>> 704 mutex_unlock(&umh_list_lock);
>> 705 return;
>> 706 out:
>> 707 if (info->cleanup)
>> 708 info->cleanup(info);
>> 709 }
>> 710
>> 711 struct ctl_table usermodehelper_table[] = {
549 { 712 {
550 .procname = "bset", 713 .procname = "bset",
551 .data = &usermodehel !! 714 .data = CAP_BSET,
552 .maxlen = 2 * sizeof(u !! 715 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
553 .mode = 0600, 716 .mode = 0600,
554 .proc_handler = proc_cap_han 717 .proc_handler = proc_cap_handler,
555 }, 718 },
556 { 719 {
557 .procname = "inheritable 720 .procname = "inheritable",
558 .data = &usermodehel !! 721 .data = CAP_PI,
559 .maxlen = 2 * sizeof(u !! 722 .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
560 .mode = 0600, 723 .mode = 0600,
561 .proc_handler = proc_cap_han 724 .proc_handler = proc_cap_handler,
562 }, 725 },
>> 726 { }
563 }; 727 };
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 */ <<
572 728
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