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 | ||
158 | write_lock_irq(&tasklist_lock); | |
159 | task_lock(task); | |
160 | ||
1da177e4 LT |
161 | /* the same process cannot be attached many times */ |
162 | if (task->ptrace & PT_PTRACED) | |
163 | goto bad; | |
ab8d11be | 164 | retval = may_attach(task); |
1da177e4 LT |
165 | if (retval) |
166 | goto bad; | |
167 | ||
168 | /* Go */ | |
169 | task->ptrace |= PT_PTRACED | ((task->real_parent != current) | |
170 | ? PT_ATTACHED : 0); | |
171 | if (capable(CAP_SYS_PTRACE)) | |
172 | task->ptrace |= PT_PTRACE_CAP; | |
1da177e4 | 173 | |
1da177e4 | 174 | __ptrace_link(task, current); |
1da177e4 LT |
175 | |
176 | force_sig_specific(SIGSTOP, task); | |
1da177e4 LT |
177 | |
178 | bad: | |
f5b40e36 | 179 | write_unlock_irq(&tasklist_lock); |
1da177e4 | 180 | task_unlock(task); |
f5b40e36 | 181 | out: |
1da177e4 LT |
182 | return retval; |
183 | } | |
184 | ||
5ecfbae0 ON |
185 | void __ptrace_detach(struct task_struct *child, unsigned int data) |
186 | { | |
187 | child->exit_code = data; | |
188 | /* .. re-parent .. */ | |
189 | __ptrace_unlink(child); | |
190 | /* .. and wake it up. */ | |
191 | if (child->exit_state != EXIT_ZOMBIE) | |
192 | wake_up_process(child); | |
193 | } | |
194 | ||
1da177e4 LT |
195 | int ptrace_detach(struct task_struct *child, unsigned int data) |
196 | { | |
7ed20e1a | 197 | if (!valid_signal(data)) |
5ecfbae0 | 198 | return -EIO; |
1da177e4 LT |
199 | |
200 | /* Architecture-specific hardware disable .. */ | |
201 | ptrace_disable(child); | |
202 | ||
1da177e4 | 203 | write_lock_irq(&tasklist_lock); |
5ecfbae0 ON |
204 | if (child->ptrace) |
205 | __ptrace_detach(child, data); | |
1da177e4 LT |
206 | write_unlock_irq(&tasklist_lock); |
207 | ||
208 | return 0; | |
209 | } | |
210 | ||
211 | /* | |
212 | * Access another process' address space. | |
213 | * Source/target buffer must be kernel space, | |
214 | * Do not walk the page table directly, use get_user_pages | |
215 | */ | |
216 | ||
217 | int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) | |
218 | { | |
219 | struct mm_struct *mm; | |
220 | struct vm_area_struct *vma; | |
221 | struct page *page; | |
222 | void *old_buf = buf; | |
223 | ||
224 | mm = get_task_mm(tsk); | |
225 | if (!mm) | |
226 | return 0; | |
227 | ||
228 | down_read(&mm->mmap_sem); | |
229 | /* ignore errors, just check how much was sucessfully transfered */ | |
230 | while (len) { | |
231 | int bytes, ret, offset; | |
232 | void *maddr; | |
233 | ||
234 | ret = get_user_pages(tsk, mm, addr, 1, | |
235 | write, 1, &page, &vma); | |
236 | if (ret <= 0) | |
237 | break; | |
238 | ||
239 | bytes = len; | |
240 | offset = addr & (PAGE_SIZE-1); | |
241 | if (bytes > PAGE_SIZE-offset) | |
242 | bytes = PAGE_SIZE-offset; | |
243 | ||
244 | maddr = kmap(page); | |
245 | if (write) { | |
246 | copy_to_user_page(vma, page, addr, | |
247 | maddr + offset, buf, bytes); | |
16bf1348 | 248 | set_page_dirty_lock(page); |
1da177e4 LT |
249 | } else { |
250 | copy_from_user_page(vma, page, addr, | |
251 | buf, maddr + offset, bytes); | |
252 | } | |
253 | kunmap(page); | |
254 | page_cache_release(page); | |
255 | len -= bytes; | |
256 | buf += bytes; | |
257 | addr += bytes; | |
258 | } | |
259 | up_read(&mm->mmap_sem); | |
260 | mmput(mm); | |
261 | ||
262 | return buf - old_buf; | |
263 | } | |
264 | ||
265 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) | |
266 | { | |
267 | int copied = 0; | |
268 | ||
269 | while (len > 0) { | |
270 | char buf[128]; | |
271 | int this_len, retval; | |
272 | ||
273 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
274 | retval = access_process_vm(tsk, src, buf, this_len, 0); | |
275 | if (!retval) { | |
276 | if (copied) | |
277 | break; | |
278 | return -EIO; | |
279 | } | |
280 | if (copy_to_user(dst, buf, retval)) | |
281 | return -EFAULT; | |
282 | copied += retval; | |
283 | src += retval; | |
284 | dst += retval; | |
285 | len -= retval; | |
286 | } | |
287 | return copied; | |
288 | } | |
289 | ||
290 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) | |
291 | { | |
292 | int copied = 0; | |
293 | ||
294 | while (len > 0) { | |
295 | char buf[128]; | |
296 | int this_len, retval; | |
297 | ||
298 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
299 | if (copy_from_user(buf, src, this_len)) | |
300 | return -EFAULT; | |
301 | retval = access_process_vm(tsk, dst, buf, this_len, 1); | |
302 | if (!retval) { | |
303 | if (copied) | |
304 | break; | |
305 | return -EIO; | |
306 | } | |
307 | copied += retval; | |
308 | src += retval; | |
309 | dst += retval; | |
310 | len -= retval; | |
311 | } | |
312 | return copied; | |
313 | } | |
314 | ||
315 | static int ptrace_setoptions(struct task_struct *child, long data) | |
316 | { | |
317 | child->ptrace &= ~PT_TRACE_MASK; | |
318 | ||
319 | if (data & PTRACE_O_TRACESYSGOOD) | |
320 | child->ptrace |= PT_TRACESYSGOOD; | |
321 | ||
322 | if (data & PTRACE_O_TRACEFORK) | |
323 | child->ptrace |= PT_TRACE_FORK; | |
324 | ||
325 | if (data & PTRACE_O_TRACEVFORK) | |
326 | child->ptrace |= PT_TRACE_VFORK; | |
327 | ||
328 | if (data & PTRACE_O_TRACECLONE) | |
329 | child->ptrace |= PT_TRACE_CLONE; | |
330 | ||
331 | if (data & PTRACE_O_TRACEEXEC) | |
332 | child->ptrace |= PT_TRACE_EXEC; | |
333 | ||
334 | if (data & PTRACE_O_TRACEVFORKDONE) | |
335 | child->ptrace |= PT_TRACE_VFORK_DONE; | |
336 | ||
337 | if (data & PTRACE_O_TRACEEXIT) | |
338 | child->ptrace |= PT_TRACE_EXIT; | |
339 | ||
340 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; | |
341 | } | |
342 | ||
343 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) | |
344 | { | |
345 | siginfo_t lastinfo; | |
346 | int error = -ESRCH; | |
347 | ||
348 | read_lock(&tasklist_lock); | |
349 | if (likely(child->sighand != NULL)) { | |
350 | error = -EINVAL; | |
351 | spin_lock_irq(&child->sighand->siglock); | |
352 | if (likely(child->last_siginfo != NULL)) { | |
353 | lastinfo = *child->last_siginfo; | |
354 | error = 0; | |
355 | } | |
356 | spin_unlock_irq(&child->sighand->siglock); | |
357 | } | |
358 | read_unlock(&tasklist_lock); | |
359 | if (!error) | |
360 | return copy_siginfo_to_user(data, &lastinfo); | |
361 | return error; | |
362 | } | |
363 | ||
364 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) | |
365 | { | |
366 | siginfo_t newinfo; | |
367 | int error = -ESRCH; | |
368 | ||
369 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) | |
370 | return -EFAULT; | |
371 | ||
372 | read_lock(&tasklist_lock); | |
373 | if (likely(child->sighand != NULL)) { | |
374 | error = -EINVAL; | |
375 | spin_lock_irq(&child->sighand->siglock); | |
376 | if (likely(child->last_siginfo != NULL)) { | |
377 | *child->last_siginfo = newinfo; | |
378 | error = 0; | |
379 | } | |
380 | spin_unlock_irq(&child->sighand->siglock); | |
381 | } | |
382 | read_unlock(&tasklist_lock); | |
383 | return error; | |
384 | } | |
385 | ||
386 | int ptrace_request(struct task_struct *child, long request, | |
387 | long addr, long data) | |
388 | { | |
389 | int ret = -EIO; | |
390 | ||
391 | switch (request) { | |
392 | #ifdef PTRACE_OLDSETOPTIONS | |
393 | case PTRACE_OLDSETOPTIONS: | |
394 | #endif | |
395 | case PTRACE_SETOPTIONS: | |
396 | ret = ptrace_setoptions(child, data); | |
397 | break; | |
398 | case PTRACE_GETEVENTMSG: | |
399 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); | |
400 | break; | |
401 | case PTRACE_GETSIGINFO: | |
402 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); | |
403 | break; | |
404 | case PTRACE_SETSIGINFO: | |
405 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); | |
406 | break; | |
407 | default: | |
408 | break; | |
409 | } | |
410 | ||
411 | return ret; | |
412 | } | |
481bed45 | 413 | |
6b9c7ed8 CH |
414 | /** |
415 | * ptrace_traceme -- helper for PTRACE_TRACEME | |
416 | * | |
417 | * Performs checks and sets PT_PTRACED. | |
418 | * Should be used by all ptrace implementations for PTRACE_TRACEME. | |
419 | */ | |
420 | int ptrace_traceme(void) | |
481bed45 | 421 | { |
f5b40e36 | 422 | int ret = -EPERM; |
481bed45 CH |
423 | |
424 | /* | |
6b9c7ed8 CH |
425 | * Are we already being traced? |
426 | */ | |
f5b40e36 LT |
427 | task_lock(current); |
428 | if (!(current->ptrace & PT_PTRACED)) { | |
429 | ret = security_ptrace(current->parent, current); | |
430 | /* | |
431 | * Set the ptrace bit in the process ptrace flags. | |
432 | */ | |
433 | if (!ret) | |
434 | current->ptrace |= PT_PTRACED; | |
435 | } | |
436 | task_unlock(current); | |
437 | return ret; | |
6b9c7ed8 | 438 | } |
481bed45 | 439 | |
6b9c7ed8 CH |
440 | /** |
441 | * ptrace_get_task_struct -- grab a task struct reference for ptrace | |
442 | * @pid: process id to grab a task_struct reference of | |
443 | * | |
444 | * This function is a helper for ptrace implementations. It checks | |
445 | * permissions and then grabs a task struct for use of the actual | |
446 | * ptrace implementation. | |
447 | * | |
448 | * Returns the task_struct for @pid or an ERR_PTR() on failure. | |
449 | */ | |
450 | struct task_struct *ptrace_get_task_struct(pid_t pid) | |
451 | { | |
452 | struct task_struct *child; | |
481bed45 CH |
453 | |
454 | /* | |
6b9c7ed8 | 455 | * Tracing init is not allowed. |
481bed45 CH |
456 | */ |
457 | if (pid == 1) | |
6b9c7ed8 | 458 | return ERR_PTR(-EPERM); |
481bed45 | 459 | |
481bed45 CH |
460 | read_lock(&tasklist_lock); |
461 | child = find_task_by_pid(pid); | |
462 | if (child) | |
463 | get_task_struct(child); | |
464 | read_unlock(&tasklist_lock); | |
465 | if (!child) | |
6b9c7ed8 CH |
466 | return ERR_PTR(-ESRCH); |
467 | return child; | |
481bed45 CH |
468 | } |
469 | ||
6b9c7ed8 | 470 | #ifndef __ARCH_SYS_PTRACE |
481bed45 CH |
471 | asmlinkage long sys_ptrace(long request, long pid, long addr, long data) |
472 | { | |
473 | struct task_struct *child; | |
474 | long ret; | |
475 | ||
476 | /* | |
477 | * This lock_kernel fixes a subtle race with suid exec | |
478 | */ | |
479 | lock_kernel(); | |
6b9c7ed8 CH |
480 | if (request == PTRACE_TRACEME) { |
481 | ret = ptrace_traceme(); | |
481bed45 | 482 | goto out; |
6b9c7ed8 CH |
483 | } |
484 | ||
485 | child = ptrace_get_task_struct(pid); | |
486 | if (IS_ERR(child)) { | |
487 | ret = PTR_ERR(child); | |
488 | goto out; | |
489 | } | |
481bed45 CH |
490 | |
491 | if (request == PTRACE_ATTACH) { | |
492 | ret = ptrace_attach(child); | |
005f18df | 493 | goto out_put_task_struct; |
481bed45 CH |
494 | } |
495 | ||
496 | ret = ptrace_check_attach(child, request == PTRACE_KILL); | |
497 | if (ret < 0) | |
498 | goto out_put_task_struct; | |
499 | ||
500 | ret = arch_ptrace(child, request, addr, data); | |
501 | if (ret < 0) | |
502 | goto out_put_task_struct; | |
503 | ||
504 | out_put_task_struct: | |
505 | put_task_struct(child); | |
506 | out: | |
507 | unlock_kernel(); | |
508 | return ret; | |
509 | } | |
510 | #endif /* __ARCH_SYS_PTRACE */ |