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