Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/kernel/ptrace.c | |
3 | * | |
4 | * (C) Copyright 1999 Linus Torvalds | |
5 | * | |
6 | * Common interfaces for "ptrace()" which we do not want | |
7 | * to continually duplicate across every architecture. | |
8 | */ | |
9 | ||
c59ede7b | 10 | #include <linux/capability.h> |
1da177e4 LT |
11 | #include <linux/module.h> |
12 | #include <linux/sched.h> | |
13 | #include <linux/errno.h> | |
14 | #include <linux/mm.h> | |
15 | #include <linux/highmem.h> | |
16 | #include <linux/pagemap.h> | |
17 | #include <linux/smp_lock.h> | |
18 | #include <linux/ptrace.h> | |
19 | #include <linux/security.h> | |
7ed20e1a | 20 | #include <linux/signal.h> |
a5cb013d | 21 | #include <linux/audit.h> |
b488893a | 22 | #include <linux/pid_namespace.h> |
1da177e4 LT |
23 | |
24 | #include <asm/pgtable.h> | |
25 | #include <asm/uaccess.h> | |
26 | ||
27 | /* | |
28 | * ptrace a task: make the debugger its new parent and | |
29 | * move it to the ptrace list. | |
30 | * | |
31 | * Must be called with the tasklist lock write-held. | |
32 | */ | |
36c8b586 | 33 | void __ptrace_link(struct task_struct *child, struct task_struct *new_parent) |
1da177e4 | 34 | { |
524223ca | 35 | BUG_ON(!list_empty(&child->ptrace_list)); |
1da177e4 LT |
36 | if (child->parent == new_parent) |
37 | return; | |
38 | list_add(&child->ptrace_list, &child->parent->ptrace_children); | |
9b678ece | 39 | remove_parent(child); |
1da177e4 | 40 | child->parent = new_parent; |
9b678ece | 41 | add_parent(child); |
1da177e4 LT |
42 | } |
43 | ||
44 | /* | |
45 | * Turn a tracing stop into a normal stop now, since with no tracer there | |
46 | * would be no way to wake it up with SIGCONT or SIGKILL. If there was a | |
47 | * signal sent that would resume the child, but didn't because it was in | |
48 | * TASK_TRACED, resume it now. | |
49 | * Requires that irqs be disabled. | |
50 | */ | |
36c8b586 | 51 | void ptrace_untrace(struct task_struct *child) |
1da177e4 LT |
52 | { |
53 | spin_lock(&child->sighand->siglock); | |
54 | if (child->state == TASK_TRACED) { | |
55 | if (child->signal->flags & SIGNAL_STOP_STOPPED) { | |
56 | child->state = TASK_STOPPED; | |
57 | } else { | |
58 | signal_wake_up(child, 1); | |
59 | } | |
60 | } | |
61 | spin_unlock(&child->sighand->siglock); | |
62 | } | |
63 | ||
64 | /* | |
65 | * unptrace a task: move it back to its original parent and | |
66 | * remove it from the ptrace list. | |
67 | * | |
68 | * Must be called with the tasklist lock write-held. | |
69 | */ | |
36c8b586 | 70 | void __ptrace_unlink(struct task_struct *child) |
1da177e4 | 71 | { |
5ecfbae0 ON |
72 | BUG_ON(!child->ptrace); |
73 | ||
1da177e4 LT |
74 | child->ptrace = 0; |
75 | if (!list_empty(&child->ptrace_list)) { | |
76 | list_del_init(&child->ptrace_list); | |
9b678ece | 77 | remove_parent(child); |
1da177e4 | 78 | child->parent = child->real_parent; |
9b678ece | 79 | add_parent(child); |
1da177e4 LT |
80 | } |
81 | ||
e57a5059 RM |
82 | if (child->state == TASK_TRACED) |
83 | ptrace_untrace(child); | |
1da177e4 LT |
84 | } |
85 | ||
86 | /* | |
87 | * Check that we have indeed attached to the thing.. | |
88 | */ | |
89 | int ptrace_check_attach(struct task_struct *child, int kill) | |
90 | { | |
91 | int ret = -ESRCH; | |
92 | ||
93 | /* | |
94 | * We take the read lock around doing both checks to close a | |
95 | * possible race where someone else was tracing our child and | |
96 | * detached between these two checks. After this locked check, | |
97 | * we are sure that this is our traced child and that can only | |
98 | * be changed by us so it's not changing right after this. | |
99 | */ | |
100 | read_lock(&tasklist_lock); | |
101 | if ((child->ptrace & PT_PTRACED) && child->parent == current && | |
102 | (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) | |
103 | && child->signal != NULL) { | |
104 | ret = 0; | |
105 | spin_lock_irq(&child->sighand->siglock); | |
106 | if (child->state == TASK_STOPPED) { | |
107 | child->state = TASK_TRACED; | |
108 | } else if (child->state != TASK_TRACED && !kill) { | |
109 | ret = -ESRCH; | |
110 | } | |
111 | spin_unlock_irq(&child->sighand->siglock); | |
112 | } | |
113 | read_unlock(&tasklist_lock); | |
114 | ||
115 | if (!ret && !kill) { | |
116 | wait_task_inactive(child); | |
117 | } | |
118 | ||
119 | /* All systems go.. */ | |
120 | return ret; | |
121 | } | |
122 | ||
ab8d11be MS |
123 | static int may_attach(struct task_struct *task) |
124 | { | |
df26c40e EB |
125 | /* May we inspect the given task? |
126 | * This check is used both for attaching with ptrace | |
127 | * and for allowing access to sensitive information in /proc. | |
128 | * | |
129 | * ptrace_attach denies several cases that /proc allows | |
130 | * because setting up the necessary parent/child relationship | |
131 | * or halting the specified task is impossible. | |
132 | */ | |
133 | int dumpable = 0; | |
134 | /* Don't let security modules deny introspection */ | |
135 | if (task == current) | |
136 | return 0; | |
ab8d11be MS |
137 | if (((current->uid != task->euid) || |
138 | (current->uid != task->suid) || | |
139 | (current->uid != task->uid) || | |
140 | (current->gid != task->egid) || | |
141 | (current->gid != task->sgid) || | |
142 | (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) | |
143 | return -EPERM; | |
144 | smp_rmb(); | |
df26c40e | 145 | if (task->mm) |
6c5d5238 | 146 | dumpable = get_dumpable(task->mm); |
df26c40e | 147 | if (!dumpable && !capable(CAP_SYS_PTRACE)) |
ab8d11be MS |
148 | return -EPERM; |
149 | ||
150 | return security_ptrace(current, task); | |
151 | } | |
152 | ||
153 | int ptrace_may_attach(struct task_struct *task) | |
154 | { | |
155 | int err; | |
156 | task_lock(task); | |
157 | err = may_attach(task); | |
158 | task_unlock(task); | |
159 | return !err; | |
160 | } | |
161 | ||
1da177e4 LT |
162 | int ptrace_attach(struct task_struct *task) |
163 | { | |
164 | int retval; | |
6175ecfe | 165 | unsigned long flags; |
f5b40e36 | 166 | |
a5cb013d AV |
167 | audit_ptrace(task); |
168 | ||
1da177e4 LT |
169 | retval = -EPERM; |
170 | if (task->pid <= 1) | |
f5b40e36 | 171 | goto out; |
bac0abd6 | 172 | if (same_thread_group(task, current)) |
f5b40e36 LT |
173 | goto out; |
174 | ||
f358166a LT |
175 | repeat: |
176 | /* | |
177 | * Nasty, nasty. | |
178 | * | |
179 | * We want to hold both the task-lock and the | |
180 | * tasklist_lock for writing at the same time. | |
181 | * But that's against the rules (tasklist_lock | |
182 | * is taken for reading by interrupts on other | |
183 | * cpu's that may have task_lock). | |
184 | */ | |
f5b40e36 | 185 | task_lock(task); |
6175ecfe | 186 | if (!write_trylock_irqsave(&tasklist_lock, flags)) { |
f358166a LT |
187 | task_unlock(task); |
188 | do { | |
189 | cpu_relax(); | |
190 | } while (!write_can_lock(&tasklist_lock)); | |
191 | goto repeat; | |
192 | } | |
f5b40e36 | 193 | |
df26c40e EB |
194 | if (!task->mm) |
195 | goto bad; | |
1da177e4 LT |
196 | /* the same process cannot be attached many times */ |
197 | if (task->ptrace & PT_PTRACED) | |
198 | goto bad; | |
ab8d11be | 199 | retval = may_attach(task); |
1da177e4 LT |
200 | if (retval) |
201 | goto bad; | |
202 | ||
203 | /* Go */ | |
204 | task->ptrace |= PT_PTRACED | ((task->real_parent != current) | |
205 | ? PT_ATTACHED : 0); | |
206 | if (capable(CAP_SYS_PTRACE)) | |
207 | task->ptrace |= PT_PTRACE_CAP; | |
1da177e4 | 208 | |
1da177e4 | 209 | __ptrace_link(task, current); |
1da177e4 LT |
210 | |
211 | force_sig_specific(SIGSTOP, task); | |
1da177e4 LT |
212 | |
213 | bad: | |
6175ecfe | 214 | write_unlock_irqrestore(&tasklist_lock, flags); |
1da177e4 | 215 | task_unlock(task); |
f5b40e36 | 216 | out: |
1da177e4 LT |
217 | return retval; |
218 | } | |
219 | ||
d5f70c00 | 220 | static inline void __ptrace_detach(struct task_struct *child, unsigned int data) |
5ecfbae0 ON |
221 | { |
222 | child->exit_code = data; | |
223 | /* .. re-parent .. */ | |
224 | __ptrace_unlink(child); | |
225 | /* .. and wake it up. */ | |
226 | if (child->exit_state != EXIT_ZOMBIE) | |
227 | wake_up_process(child); | |
228 | } | |
229 | ||
1da177e4 LT |
230 | int ptrace_detach(struct task_struct *child, unsigned int data) |
231 | { | |
7ed20e1a | 232 | if (!valid_signal(data)) |
5ecfbae0 | 233 | return -EIO; |
1da177e4 LT |
234 | |
235 | /* Architecture-specific hardware disable .. */ | |
236 | ptrace_disable(child); | |
7d941432 | 237 | clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); |
1da177e4 | 238 | |
1da177e4 | 239 | write_lock_irq(&tasklist_lock); |
d5f70c00 | 240 | /* protect against de_thread()->release_task() */ |
5ecfbae0 ON |
241 | if (child->ptrace) |
242 | __ptrace_detach(child, data); | |
1da177e4 LT |
243 | write_unlock_irq(&tasklist_lock); |
244 | ||
245 | return 0; | |
246 | } | |
247 | ||
1da177e4 LT |
248 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) |
249 | { | |
250 | int copied = 0; | |
251 | ||
252 | while (len > 0) { | |
253 | char buf[128]; | |
254 | int this_len, retval; | |
255 | ||
256 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
257 | retval = access_process_vm(tsk, src, buf, this_len, 0); | |
258 | if (!retval) { | |
259 | if (copied) | |
260 | break; | |
261 | return -EIO; | |
262 | } | |
263 | if (copy_to_user(dst, buf, retval)) | |
264 | return -EFAULT; | |
265 | copied += retval; | |
266 | src += retval; | |
267 | dst += retval; | |
268 | len -= retval; | |
269 | } | |
270 | return copied; | |
271 | } | |
272 | ||
273 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) | |
274 | { | |
275 | int copied = 0; | |
276 | ||
277 | while (len > 0) { | |
278 | char buf[128]; | |
279 | int this_len, retval; | |
280 | ||
281 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
282 | if (copy_from_user(buf, src, this_len)) | |
283 | return -EFAULT; | |
284 | retval = access_process_vm(tsk, dst, buf, this_len, 1); | |
285 | if (!retval) { | |
286 | if (copied) | |
287 | break; | |
288 | return -EIO; | |
289 | } | |
290 | copied += retval; | |
291 | src += retval; | |
292 | dst += retval; | |
293 | len -= retval; | |
294 | } | |
295 | return copied; | |
296 | } | |
297 | ||
298 | static int ptrace_setoptions(struct task_struct *child, long data) | |
299 | { | |
300 | child->ptrace &= ~PT_TRACE_MASK; | |
301 | ||
302 | if (data & PTRACE_O_TRACESYSGOOD) | |
303 | child->ptrace |= PT_TRACESYSGOOD; | |
304 | ||
305 | if (data & PTRACE_O_TRACEFORK) | |
306 | child->ptrace |= PT_TRACE_FORK; | |
307 | ||
308 | if (data & PTRACE_O_TRACEVFORK) | |
309 | child->ptrace |= PT_TRACE_VFORK; | |
310 | ||
311 | if (data & PTRACE_O_TRACECLONE) | |
312 | child->ptrace |= PT_TRACE_CLONE; | |
313 | ||
314 | if (data & PTRACE_O_TRACEEXEC) | |
315 | child->ptrace |= PT_TRACE_EXEC; | |
316 | ||
317 | if (data & PTRACE_O_TRACEVFORKDONE) | |
318 | child->ptrace |= PT_TRACE_VFORK_DONE; | |
319 | ||
320 | if (data & PTRACE_O_TRACEEXIT) | |
321 | child->ptrace |= PT_TRACE_EXIT; | |
322 | ||
323 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; | |
324 | } | |
325 | ||
326 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) | |
327 | { | |
328 | siginfo_t lastinfo; | |
329 | int error = -ESRCH; | |
330 | ||
331 | read_lock(&tasklist_lock); | |
332 | if (likely(child->sighand != NULL)) { | |
333 | error = -EINVAL; | |
334 | spin_lock_irq(&child->sighand->siglock); | |
335 | if (likely(child->last_siginfo != NULL)) { | |
336 | lastinfo = *child->last_siginfo; | |
337 | error = 0; | |
338 | } | |
339 | spin_unlock_irq(&child->sighand->siglock); | |
340 | } | |
341 | read_unlock(&tasklist_lock); | |
342 | if (!error) | |
343 | return copy_siginfo_to_user(data, &lastinfo); | |
344 | return error; | |
345 | } | |
346 | ||
347 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) | |
348 | { | |
349 | siginfo_t newinfo; | |
350 | int error = -ESRCH; | |
351 | ||
352 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) | |
353 | return -EFAULT; | |
354 | ||
355 | read_lock(&tasklist_lock); | |
356 | if (likely(child->sighand != NULL)) { | |
357 | error = -EINVAL; | |
358 | spin_lock_irq(&child->sighand->siglock); | |
359 | if (likely(child->last_siginfo != NULL)) { | |
360 | *child->last_siginfo = newinfo; | |
361 | error = 0; | |
362 | } | |
363 | spin_unlock_irq(&child->sighand->siglock); | |
364 | } | |
365 | read_unlock(&tasklist_lock); | |
366 | return error; | |
367 | } | |
368 | ||
369 | int ptrace_request(struct task_struct *child, long request, | |
370 | long addr, long data) | |
371 | { | |
372 | int ret = -EIO; | |
373 | ||
374 | switch (request) { | |
375 | #ifdef PTRACE_OLDSETOPTIONS | |
376 | case PTRACE_OLDSETOPTIONS: | |
377 | #endif | |
378 | case PTRACE_SETOPTIONS: | |
379 | ret = ptrace_setoptions(child, data); | |
380 | break; | |
381 | case PTRACE_GETEVENTMSG: | |
382 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); | |
383 | break; | |
384 | case PTRACE_GETSIGINFO: | |
385 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); | |
386 | break; | |
387 | case PTRACE_SETSIGINFO: | |
388 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); | |
389 | break; | |
1bcf5482 AD |
390 | case PTRACE_DETACH: /* detach a process that was attached. */ |
391 | ret = ptrace_detach(child, data); | |
392 | break; | |
1da177e4 LT |
393 | default: |
394 | break; | |
395 | } | |
396 | ||
397 | return ret; | |
398 | } | |
481bed45 | 399 | |
6b9c7ed8 CH |
400 | /** |
401 | * ptrace_traceme -- helper for PTRACE_TRACEME | |
402 | * | |
403 | * Performs checks and sets PT_PTRACED. | |
404 | * Should be used by all ptrace implementations for PTRACE_TRACEME. | |
405 | */ | |
406 | int ptrace_traceme(void) | |
481bed45 | 407 | { |
f5b40e36 | 408 | int ret = -EPERM; |
481bed45 CH |
409 | |
410 | /* | |
6b9c7ed8 CH |
411 | * Are we already being traced? |
412 | */ | |
f5b40e36 LT |
413 | task_lock(current); |
414 | if (!(current->ptrace & PT_PTRACED)) { | |
415 | ret = security_ptrace(current->parent, current); | |
416 | /* | |
417 | * Set the ptrace bit in the process ptrace flags. | |
418 | */ | |
419 | if (!ret) | |
420 | current->ptrace |= PT_PTRACED; | |
421 | } | |
422 | task_unlock(current); | |
423 | return ret; | |
6b9c7ed8 | 424 | } |
481bed45 | 425 | |
6b9c7ed8 CH |
426 | /** |
427 | * ptrace_get_task_struct -- grab a task struct reference for ptrace | |
428 | * @pid: process id to grab a task_struct reference of | |
429 | * | |
430 | * This function is a helper for ptrace implementations. It checks | |
431 | * permissions and then grabs a task struct for use of the actual | |
432 | * ptrace implementation. | |
433 | * | |
434 | * Returns the task_struct for @pid or an ERR_PTR() on failure. | |
435 | */ | |
436 | struct task_struct *ptrace_get_task_struct(pid_t pid) | |
437 | { | |
438 | struct task_struct *child; | |
481bed45 CH |
439 | |
440 | /* | |
6b9c7ed8 | 441 | * Tracing init is not allowed. |
481bed45 CH |
442 | */ |
443 | if (pid == 1) | |
6b9c7ed8 | 444 | return ERR_PTR(-EPERM); |
481bed45 | 445 | |
481bed45 | 446 | read_lock(&tasklist_lock); |
228ebcbe | 447 | child = find_task_by_vpid(pid); |
481bed45 CH |
448 | if (child) |
449 | get_task_struct(child); | |
f400e198 | 450 | |
481bed45 CH |
451 | read_unlock(&tasklist_lock); |
452 | if (!child) | |
6b9c7ed8 CH |
453 | return ERR_PTR(-ESRCH); |
454 | return child; | |
481bed45 CH |
455 | } |
456 | ||
0ac15559 CH |
457 | #ifndef arch_ptrace_attach |
458 | #define arch_ptrace_attach(child) do { } while (0) | |
459 | #endif | |
460 | ||
6b9c7ed8 | 461 | #ifndef __ARCH_SYS_PTRACE |
481bed45 CH |
462 | asmlinkage long sys_ptrace(long request, long pid, long addr, long data) |
463 | { | |
464 | struct task_struct *child; | |
465 | long ret; | |
466 | ||
467 | /* | |
468 | * This lock_kernel fixes a subtle race with suid exec | |
469 | */ | |
470 | lock_kernel(); | |
6b9c7ed8 CH |
471 | if (request == PTRACE_TRACEME) { |
472 | ret = ptrace_traceme(); | |
481bed45 | 473 | goto out; |
6b9c7ed8 CH |
474 | } |
475 | ||
476 | child = ptrace_get_task_struct(pid); | |
477 | if (IS_ERR(child)) { | |
478 | ret = PTR_ERR(child); | |
479 | goto out; | |
480 | } | |
481bed45 CH |
481 | |
482 | if (request == PTRACE_ATTACH) { | |
483 | ret = ptrace_attach(child); | |
0ac15559 CH |
484 | /* |
485 | * Some architectures need to do book-keeping after | |
486 | * a ptrace attach. | |
487 | */ | |
488 | if (!ret) | |
489 | arch_ptrace_attach(child); | |
005f18df | 490 | goto out_put_task_struct; |
481bed45 CH |
491 | } |
492 | ||
493 | ret = ptrace_check_attach(child, request == PTRACE_KILL); | |
494 | if (ret < 0) | |
495 | goto out_put_task_struct; | |
496 | ||
497 | ret = arch_ptrace(child, request, addr, data); | |
498 | if (ret < 0) | |
499 | goto out_put_task_struct; | |
500 | ||
501 | out_put_task_struct: | |
502 | put_task_struct(child); | |
503 | out: | |
504 | unlock_kernel(); | |
505 | return ret; | |
506 | } | |
507 | #endif /* __ARCH_SYS_PTRACE */ | |
76647323 AD |
508 | |
509 | int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data) | |
510 | { | |
511 | unsigned long tmp; | |
512 | int copied; | |
513 | ||
514 | copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0); | |
515 | if (copied != sizeof(tmp)) | |
516 | return -EIO; | |
517 | return put_user(tmp, (unsigned long __user *)data); | |
518 | } | |
f284ce72 AD |
519 | |
520 | int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data) | |
521 | { | |
522 | int copied; | |
523 | ||
524 | copied = access_process_vm(tsk, addr, &data, sizeof(data), 1); | |
525 | return (copied == sizeof(data)) ? 0 : -EIO; | |
526 | } |