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> |
1da177e4 LT |
21 | |
22 | #include <asm/pgtable.h> | |
23 | #include <asm/uaccess.h> | |
24 | ||
25 | /* | |
26 | * ptrace a task: make the debugger its new parent and | |
27 | * move it to the ptrace list. | |
28 | * | |
29 | * Must be called with the tasklist lock write-held. | |
30 | */ | |
31 | void __ptrace_link(task_t *child, task_t *new_parent) | |
32 | { | |
524223ca | 33 | BUG_ON(!list_empty(&child->ptrace_list)); |
1da177e4 LT |
34 | if (child->parent == new_parent) |
35 | return; | |
36 | list_add(&child->ptrace_list, &child->parent->ptrace_children); | |
9b678ece | 37 | remove_parent(child); |
1da177e4 | 38 | child->parent = new_parent; |
9b678ece | 39 | add_parent(child); |
1da177e4 LT |
40 | } |
41 | ||
42 | /* | |
43 | * Turn a tracing stop into a normal stop now, since with no tracer there | |
44 | * would be no way to wake it up with SIGCONT or SIGKILL. If there was a | |
45 | * signal sent that would resume the child, but didn't because it was in | |
46 | * TASK_TRACED, resume it now. | |
47 | * Requires that irqs be disabled. | |
48 | */ | |
49 | void ptrace_untrace(task_t *child) | |
50 | { | |
51 | spin_lock(&child->sighand->siglock); | |
52 | if (child->state == TASK_TRACED) { | |
53 | if (child->signal->flags & SIGNAL_STOP_STOPPED) { | |
54 | child->state = TASK_STOPPED; | |
55 | } else { | |
56 | signal_wake_up(child, 1); | |
57 | } | |
58 | } | |
59 | spin_unlock(&child->sighand->siglock); | |
60 | } | |
61 | ||
62 | /* | |
63 | * unptrace a task: move it back to its original parent and | |
64 | * remove it from the ptrace list. | |
65 | * | |
66 | * Must be called with the tasklist lock write-held. | |
67 | */ | |
68 | void __ptrace_unlink(task_t *child) | |
69 | { | |
5ecfbae0 ON |
70 | BUG_ON(!child->ptrace); |
71 | ||
1da177e4 LT |
72 | child->ptrace = 0; |
73 | if (!list_empty(&child->ptrace_list)) { | |
74 | list_del_init(&child->ptrace_list); | |
9b678ece | 75 | remove_parent(child); |
1da177e4 | 76 | child->parent = child->real_parent; |
9b678ece | 77 | add_parent(child); |
1da177e4 LT |
78 | } |
79 | ||
e57a5059 RM |
80 | if (child->state == TASK_TRACED) |
81 | ptrace_untrace(child); | |
1da177e4 LT |
82 | } |
83 | ||
84 | /* | |
85 | * Check that we have indeed attached to the thing.. | |
86 | */ | |
87 | int ptrace_check_attach(struct task_struct *child, int kill) | |
88 | { | |
89 | int ret = -ESRCH; | |
90 | ||
91 | /* | |
92 | * We take the read lock around doing both checks to close a | |
93 | * possible race where someone else was tracing our child and | |
94 | * detached between these two checks. After this locked check, | |
95 | * we are sure that this is our traced child and that can only | |
96 | * be changed by us so it's not changing right after this. | |
97 | */ | |
98 | read_lock(&tasklist_lock); | |
99 | if ((child->ptrace & PT_PTRACED) && child->parent == current && | |
100 | (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) | |
101 | && child->signal != NULL) { | |
102 | ret = 0; | |
103 | spin_lock_irq(&child->sighand->siglock); | |
104 | if (child->state == TASK_STOPPED) { | |
105 | child->state = TASK_TRACED; | |
106 | } else if (child->state != TASK_TRACED && !kill) { | |
107 | ret = -ESRCH; | |
108 | } | |
109 | spin_unlock_irq(&child->sighand->siglock); | |
110 | } | |
111 | read_unlock(&tasklist_lock); | |
112 | ||
113 | if (!ret && !kill) { | |
114 | wait_task_inactive(child); | |
115 | } | |
116 | ||
117 | /* All systems go.. */ | |
118 | return ret; | |
119 | } | |
120 | ||
ab8d11be MS |
121 | static int may_attach(struct task_struct *task) |
122 | { | |
123 | if (!task->mm) | |
124 | return -EPERM; | |
125 | if (((current->uid != task->euid) || | |
126 | (current->uid != task->suid) || | |
127 | (current->uid != task->uid) || | |
128 | (current->gid != task->egid) || | |
129 | (current->gid != task->sgid) || | |
130 | (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) | |
131 | return -EPERM; | |
132 | smp_rmb(); | |
133 | if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) | |
134 | return -EPERM; | |
135 | ||
136 | return security_ptrace(current, task); | |
137 | } | |
138 | ||
139 | int ptrace_may_attach(struct task_struct *task) | |
140 | { | |
141 | int err; | |
142 | task_lock(task); | |
143 | err = may_attach(task); | |
144 | task_unlock(task); | |
145 | return !err; | |
146 | } | |
147 | ||
1da177e4 LT |
148 | int ptrace_attach(struct task_struct *task) |
149 | { | |
150 | int retval; | |
f5b40e36 | 151 | |
1da177e4 LT |
152 | retval = -EPERM; |
153 | if (task->pid <= 1) | |
f5b40e36 | 154 | goto out; |
28d838cc | 155 | if (task->tgid == current->tgid) |
f5b40e36 LT |
156 | goto out; |
157 | ||
f358166a LT |
158 | repeat: |
159 | /* | |
160 | * Nasty, nasty. | |
161 | * | |
162 | * We want to hold both the task-lock and the | |
163 | * tasklist_lock for writing at the same time. | |
164 | * But that's against the rules (tasklist_lock | |
165 | * is taken for reading by interrupts on other | |
166 | * cpu's that may have task_lock). | |
167 | */ | |
f5b40e36 | 168 | task_lock(task); |
f358166a LT |
169 | local_irq_disable(); |
170 | if (!write_trylock(&tasklist_lock)) { | |
171 | local_irq_enable(); | |
172 | task_unlock(task); | |
173 | do { | |
174 | cpu_relax(); | |
175 | } while (!write_can_lock(&tasklist_lock)); | |
176 | goto repeat; | |
177 | } | |
f5b40e36 | 178 | |
1da177e4 LT |
179 | /* the same process cannot be attached many times */ |
180 | if (task->ptrace & PT_PTRACED) | |
181 | goto bad; | |
ab8d11be | 182 | retval = may_attach(task); |
1da177e4 LT |
183 | if (retval) |
184 | goto bad; | |
185 | ||
186 | /* Go */ | |
187 | task->ptrace |= PT_PTRACED | ((task->real_parent != current) | |
188 | ? PT_ATTACHED : 0); | |
189 | if (capable(CAP_SYS_PTRACE)) | |
190 | task->ptrace |= PT_PTRACE_CAP; | |
1da177e4 | 191 | |
1da177e4 | 192 | __ptrace_link(task, current); |
1da177e4 LT |
193 | |
194 | force_sig_specific(SIGSTOP, task); | |
1da177e4 LT |
195 | |
196 | bad: | |
f5b40e36 | 197 | write_unlock_irq(&tasklist_lock); |
1da177e4 | 198 | task_unlock(task); |
f5b40e36 | 199 | out: |
1da177e4 LT |
200 | return retval; |
201 | } | |
202 | ||
5ecfbae0 ON |
203 | void __ptrace_detach(struct task_struct *child, unsigned int data) |
204 | { | |
205 | child->exit_code = data; | |
206 | /* .. re-parent .. */ | |
207 | __ptrace_unlink(child); | |
208 | /* .. and wake it up. */ | |
209 | if (child->exit_state != EXIT_ZOMBIE) | |
210 | wake_up_process(child); | |
211 | } | |
212 | ||
1da177e4 LT |
213 | int ptrace_detach(struct task_struct *child, unsigned int data) |
214 | { | |
7ed20e1a | 215 | if (!valid_signal(data)) |
5ecfbae0 | 216 | return -EIO; |
1da177e4 LT |
217 | |
218 | /* Architecture-specific hardware disable .. */ | |
219 | ptrace_disable(child); | |
220 | ||
1da177e4 | 221 | write_lock_irq(&tasklist_lock); |
5ecfbae0 ON |
222 | if (child->ptrace) |
223 | __ptrace_detach(child, data); | |
1da177e4 LT |
224 | write_unlock_irq(&tasklist_lock); |
225 | ||
226 | return 0; | |
227 | } | |
228 | ||
229 | /* | |
230 | * Access another process' address space. | |
231 | * Source/target buffer must be kernel space, | |
232 | * Do not walk the page table directly, use get_user_pages | |
233 | */ | |
234 | ||
235 | int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) | |
236 | { | |
237 | struct mm_struct *mm; | |
238 | struct vm_area_struct *vma; | |
239 | struct page *page; | |
240 | void *old_buf = buf; | |
241 | ||
242 | mm = get_task_mm(tsk); | |
243 | if (!mm) | |
244 | return 0; | |
245 | ||
246 | down_read(&mm->mmap_sem); | |
247 | /* ignore errors, just check how much was sucessfully transfered */ | |
248 | while (len) { | |
249 | int bytes, ret, offset; | |
250 | void *maddr; | |
251 | ||
252 | ret = get_user_pages(tsk, mm, addr, 1, | |
253 | write, 1, &page, &vma); | |
254 | if (ret <= 0) | |
255 | break; | |
256 | ||
257 | bytes = len; | |
258 | offset = addr & (PAGE_SIZE-1); | |
259 | if (bytes > PAGE_SIZE-offset) | |
260 | bytes = PAGE_SIZE-offset; | |
261 | ||
262 | maddr = kmap(page); | |
263 | if (write) { | |
264 | copy_to_user_page(vma, page, addr, | |
265 | maddr + offset, buf, bytes); | |
16bf1348 | 266 | set_page_dirty_lock(page); |
1da177e4 LT |
267 | } else { |
268 | copy_from_user_page(vma, page, addr, | |
269 | buf, maddr + offset, bytes); | |
270 | } | |
271 | kunmap(page); | |
272 | page_cache_release(page); | |
273 | len -= bytes; | |
274 | buf += bytes; | |
275 | addr += bytes; | |
276 | } | |
277 | up_read(&mm->mmap_sem); | |
278 | mmput(mm); | |
279 | ||
280 | return buf - old_buf; | |
281 | } | |
282 | ||
283 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) | |
284 | { | |
285 | int copied = 0; | |
286 | ||
287 | while (len > 0) { | |
288 | char buf[128]; | |
289 | int this_len, retval; | |
290 | ||
291 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
292 | retval = access_process_vm(tsk, src, buf, this_len, 0); | |
293 | if (!retval) { | |
294 | if (copied) | |
295 | break; | |
296 | return -EIO; | |
297 | } | |
298 | if (copy_to_user(dst, buf, retval)) | |
299 | return -EFAULT; | |
300 | copied += retval; | |
301 | src += retval; | |
302 | dst += retval; | |
303 | len -= retval; | |
304 | } | |
305 | return copied; | |
306 | } | |
307 | ||
308 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) | |
309 | { | |
310 | int copied = 0; | |
311 | ||
312 | while (len > 0) { | |
313 | char buf[128]; | |
314 | int this_len, retval; | |
315 | ||
316 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
317 | if (copy_from_user(buf, src, this_len)) | |
318 | return -EFAULT; | |
319 | retval = access_process_vm(tsk, dst, buf, this_len, 1); | |
320 | if (!retval) { | |
321 | if (copied) | |
322 | break; | |
323 | return -EIO; | |
324 | } | |
325 | copied += retval; | |
326 | src += retval; | |
327 | dst += retval; | |
328 | len -= retval; | |
329 | } | |
330 | return copied; | |
331 | } | |
332 | ||
333 | static int ptrace_setoptions(struct task_struct *child, long data) | |
334 | { | |
335 | child->ptrace &= ~PT_TRACE_MASK; | |
336 | ||
337 | if (data & PTRACE_O_TRACESYSGOOD) | |
338 | child->ptrace |= PT_TRACESYSGOOD; | |
339 | ||
340 | if (data & PTRACE_O_TRACEFORK) | |
341 | child->ptrace |= PT_TRACE_FORK; | |
342 | ||
343 | if (data & PTRACE_O_TRACEVFORK) | |
344 | child->ptrace |= PT_TRACE_VFORK; | |
345 | ||
346 | if (data & PTRACE_O_TRACECLONE) | |
347 | child->ptrace |= PT_TRACE_CLONE; | |
348 | ||
349 | if (data & PTRACE_O_TRACEEXEC) | |
350 | child->ptrace |= PT_TRACE_EXEC; | |
351 | ||
352 | if (data & PTRACE_O_TRACEVFORKDONE) | |
353 | child->ptrace |= PT_TRACE_VFORK_DONE; | |
354 | ||
355 | if (data & PTRACE_O_TRACEEXIT) | |
356 | child->ptrace |= PT_TRACE_EXIT; | |
357 | ||
358 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; | |
359 | } | |
360 | ||
361 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) | |
362 | { | |
363 | siginfo_t lastinfo; | |
364 | int error = -ESRCH; | |
365 | ||
366 | read_lock(&tasklist_lock); | |
367 | if (likely(child->sighand != NULL)) { | |
368 | error = -EINVAL; | |
369 | spin_lock_irq(&child->sighand->siglock); | |
370 | if (likely(child->last_siginfo != NULL)) { | |
371 | lastinfo = *child->last_siginfo; | |
372 | error = 0; | |
373 | } | |
374 | spin_unlock_irq(&child->sighand->siglock); | |
375 | } | |
376 | read_unlock(&tasklist_lock); | |
377 | if (!error) | |
378 | return copy_siginfo_to_user(data, &lastinfo); | |
379 | return error; | |
380 | } | |
381 | ||
382 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) | |
383 | { | |
384 | siginfo_t newinfo; | |
385 | int error = -ESRCH; | |
386 | ||
387 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) | |
388 | return -EFAULT; | |
389 | ||
390 | read_lock(&tasklist_lock); | |
391 | if (likely(child->sighand != NULL)) { | |
392 | error = -EINVAL; | |
393 | spin_lock_irq(&child->sighand->siglock); | |
394 | if (likely(child->last_siginfo != NULL)) { | |
395 | *child->last_siginfo = newinfo; | |
396 | error = 0; | |
397 | } | |
398 | spin_unlock_irq(&child->sighand->siglock); | |
399 | } | |
400 | read_unlock(&tasklist_lock); | |
401 | return error; | |
402 | } | |
403 | ||
404 | int ptrace_request(struct task_struct *child, long request, | |
405 | long addr, long data) | |
406 | { | |
407 | int ret = -EIO; | |
408 | ||
409 | switch (request) { | |
410 | #ifdef PTRACE_OLDSETOPTIONS | |
411 | case PTRACE_OLDSETOPTIONS: | |
412 | #endif | |
413 | case PTRACE_SETOPTIONS: | |
414 | ret = ptrace_setoptions(child, data); | |
415 | break; | |
416 | case PTRACE_GETEVENTMSG: | |
417 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); | |
418 | break; | |
419 | case PTRACE_GETSIGINFO: | |
420 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); | |
421 | break; | |
422 | case PTRACE_SETSIGINFO: | |
423 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); | |
424 | break; | |
425 | default: | |
426 | break; | |
427 | } | |
428 | ||
429 | return ret; | |
430 | } | |
481bed45 | 431 | |
6b9c7ed8 CH |
432 | /** |
433 | * ptrace_traceme -- helper for PTRACE_TRACEME | |
434 | * | |
435 | * Performs checks and sets PT_PTRACED. | |
436 | * Should be used by all ptrace implementations for PTRACE_TRACEME. | |
437 | */ | |
438 | int ptrace_traceme(void) | |
481bed45 | 439 | { |
f5b40e36 | 440 | int ret = -EPERM; |
481bed45 CH |
441 | |
442 | /* | |
6b9c7ed8 CH |
443 | * Are we already being traced? |
444 | */ | |
f5b40e36 LT |
445 | task_lock(current); |
446 | if (!(current->ptrace & PT_PTRACED)) { | |
447 | ret = security_ptrace(current->parent, current); | |
448 | /* | |
449 | * Set the ptrace bit in the process ptrace flags. | |
450 | */ | |
451 | if (!ret) | |
452 | current->ptrace |= PT_PTRACED; | |
453 | } | |
454 | task_unlock(current); | |
455 | return ret; | |
6b9c7ed8 | 456 | } |
481bed45 | 457 | |
6b9c7ed8 CH |
458 | /** |
459 | * ptrace_get_task_struct -- grab a task struct reference for ptrace | |
460 | * @pid: process id to grab a task_struct reference of | |
461 | * | |
462 | * This function is a helper for ptrace implementations. It checks | |
463 | * permissions and then grabs a task struct for use of the actual | |
464 | * ptrace implementation. | |
465 | * | |
466 | * Returns the task_struct for @pid or an ERR_PTR() on failure. | |
467 | */ | |
468 | struct task_struct *ptrace_get_task_struct(pid_t pid) | |
469 | { | |
470 | struct task_struct *child; | |
481bed45 CH |
471 | |
472 | /* | |
6b9c7ed8 | 473 | * Tracing init is not allowed. |
481bed45 CH |
474 | */ |
475 | if (pid == 1) | |
6b9c7ed8 | 476 | return ERR_PTR(-EPERM); |
481bed45 | 477 | |
481bed45 CH |
478 | read_lock(&tasklist_lock); |
479 | child = find_task_by_pid(pid); | |
480 | if (child) | |
481 | get_task_struct(child); | |
482 | read_unlock(&tasklist_lock); | |
483 | if (!child) | |
6b9c7ed8 CH |
484 | return ERR_PTR(-ESRCH); |
485 | return child; | |
481bed45 CH |
486 | } |
487 | ||
6b9c7ed8 | 488 | #ifndef __ARCH_SYS_PTRACE |
481bed45 CH |
489 | asmlinkage long sys_ptrace(long request, long pid, long addr, long data) |
490 | { | |
491 | struct task_struct *child; | |
492 | long ret; | |
493 | ||
494 | /* | |
495 | * This lock_kernel fixes a subtle race with suid exec | |
496 | */ | |
497 | lock_kernel(); | |
6b9c7ed8 CH |
498 | if (request == PTRACE_TRACEME) { |
499 | ret = ptrace_traceme(); | |
481bed45 | 500 | goto out; |
6b9c7ed8 CH |
501 | } |
502 | ||
503 | child = ptrace_get_task_struct(pid); | |
504 | if (IS_ERR(child)) { | |
505 | ret = PTR_ERR(child); | |
506 | goto out; | |
507 | } | |
481bed45 CH |
508 | |
509 | if (request == PTRACE_ATTACH) { | |
510 | ret = ptrace_attach(child); | |
005f18df | 511 | goto out_put_task_struct; |
481bed45 CH |
512 | } |
513 | ||
514 | ret = ptrace_check_attach(child, request == PTRACE_KILL); | |
515 | if (ret < 0) | |
516 | goto out_put_task_struct; | |
517 | ||
518 | ret = arch_ptrace(child, request, addr, data); | |
519 | if (ret < 0) | |
520 | goto out_put_task_struct; | |
521 | ||
522 | out_put_task_struct: | |
523 | put_task_struct(child); | |
524 | out: | |
525 | unlock_kernel(); | |
526 | return ret; | |
527 | } | |
528 | #endif /* __ARCH_SYS_PTRACE */ |