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 | { | |
33 | if (!list_empty(&child->ptrace_list)) | |
34 | BUG(); | |
35 | if (child->parent == new_parent) | |
36 | return; | |
37 | list_add(&child->ptrace_list, &child->parent->ptrace_children); | |
9b678ece | 38 | remove_parent(child); |
1da177e4 | 39 | child->parent = new_parent; |
9b678ece | 40 | add_parent(child); |
1da177e4 LT |
41 | } |
42 | ||
43 | /* | |
44 | * Turn a tracing stop into a normal stop now, since with no tracer there | |
45 | * would be no way to wake it up with SIGCONT or SIGKILL. If there was a | |
46 | * signal sent that would resume the child, but didn't because it was in | |
47 | * TASK_TRACED, resume it now. | |
48 | * Requires that irqs be disabled. | |
49 | */ | |
50 | void ptrace_untrace(task_t *child) | |
51 | { | |
52 | spin_lock(&child->sighand->siglock); | |
53 | if (child->state == TASK_TRACED) { | |
54 | if (child->signal->flags & SIGNAL_STOP_STOPPED) { | |
55 | child->state = TASK_STOPPED; | |
56 | } else { | |
57 | signal_wake_up(child, 1); | |
58 | } | |
59 | } | |
30e0fca6 AA |
60 | if (child->signal->flags & SIGNAL_GROUP_EXIT) { |
61 | sigaddset(&child->pending.signal, SIGKILL); | |
62 | signal_wake_up(child, 1); | |
63 | } | |
1da177e4 LT |
64 | spin_unlock(&child->sighand->siglock); |
65 | } | |
66 | ||
67 | /* | |
68 | * unptrace a task: move it back to its original parent and | |
69 | * remove it from the ptrace list. | |
70 | * | |
71 | * Must be called with the tasklist lock write-held. | |
72 | */ | |
73 | void __ptrace_unlink(task_t *child) | |
74 | { | |
5ecfbae0 ON |
75 | BUG_ON(!child->ptrace); |
76 | ||
1da177e4 LT |
77 | child->ptrace = 0; |
78 | if (!list_empty(&child->ptrace_list)) { | |
79 | list_del_init(&child->ptrace_list); | |
9b678ece | 80 | remove_parent(child); |
1da177e4 | 81 | child->parent = child->real_parent; |
9b678ece | 82 | add_parent(child); |
1da177e4 LT |
83 | } |
84 | ||
30e0fca6 | 85 | ptrace_untrace(child); |
1da177e4 LT |
86 | } |
87 | ||
88 | /* | |
89 | * Check that we have indeed attached to the thing.. | |
90 | */ | |
91 | int ptrace_check_attach(struct task_struct *child, int kill) | |
92 | { | |
93 | int ret = -ESRCH; | |
94 | ||
95 | /* | |
96 | * We take the read lock around doing both checks to close a | |
97 | * possible race where someone else was tracing our child and | |
98 | * detached between these two checks. After this locked check, | |
99 | * we are sure that this is our traced child and that can only | |
100 | * be changed by us so it's not changing right after this. | |
101 | */ | |
102 | read_lock(&tasklist_lock); | |
103 | if ((child->ptrace & PT_PTRACED) && child->parent == current && | |
104 | (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) | |
105 | && child->signal != NULL) { | |
106 | ret = 0; | |
107 | spin_lock_irq(&child->sighand->siglock); | |
108 | if (child->state == TASK_STOPPED) { | |
109 | child->state = TASK_TRACED; | |
110 | } else if (child->state != TASK_TRACED && !kill) { | |
111 | ret = -ESRCH; | |
112 | } | |
113 | spin_unlock_irq(&child->sighand->siglock); | |
114 | } | |
115 | read_unlock(&tasklist_lock); | |
116 | ||
117 | if (!ret && !kill) { | |
118 | wait_task_inactive(child); | |
119 | } | |
120 | ||
121 | /* All systems go.. */ | |
122 | return ret; | |
123 | } | |
124 | ||
ab8d11be MS |
125 | static int may_attach(struct task_struct *task) |
126 | { | |
127 | if (!task->mm) | |
128 | return -EPERM; | |
129 | if (((current->uid != task->euid) || | |
130 | (current->uid != task->suid) || | |
131 | (current->uid != task->uid) || | |
132 | (current->gid != task->egid) || | |
133 | (current->gid != task->sgid) || | |
134 | (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) | |
135 | return -EPERM; | |
136 | smp_rmb(); | |
137 | if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) | |
138 | return -EPERM; | |
139 | ||
140 | return security_ptrace(current, task); | |
141 | } | |
142 | ||
143 | int ptrace_may_attach(struct task_struct *task) | |
144 | { | |
145 | int err; | |
146 | task_lock(task); | |
147 | err = may_attach(task); | |
148 | task_unlock(task); | |
149 | return !err; | |
150 | } | |
151 | ||
1da177e4 LT |
152 | int ptrace_attach(struct task_struct *task) |
153 | { | |
154 | int retval; | |
155 | task_lock(task); | |
156 | retval = -EPERM; | |
157 | if (task->pid <= 1) | |
158 | goto bad; | |
28d838cc | 159 | if (task->tgid == current->tgid) |
1da177e4 | 160 | goto bad; |
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; | |
173 | task_unlock(task); | |
174 | ||
175 | write_lock_irq(&tasklist_lock); | |
176 | __ptrace_link(task, current); | |
177 | write_unlock_irq(&tasklist_lock); | |
178 | ||
179 | force_sig_specific(SIGSTOP, task); | |
180 | return 0; | |
181 | ||
182 | bad: | |
183 | task_unlock(task); | |
184 | return retval; | |
185 | } | |
186 | ||
5ecfbae0 ON |
187 | void __ptrace_detach(struct task_struct *child, unsigned int data) |
188 | { | |
189 | child->exit_code = data; | |
190 | /* .. re-parent .. */ | |
191 | __ptrace_unlink(child); | |
192 | /* .. and wake it up. */ | |
193 | if (child->exit_state != EXIT_ZOMBIE) | |
194 | wake_up_process(child); | |
195 | } | |
196 | ||
1da177e4 LT |
197 | int ptrace_detach(struct task_struct *child, unsigned int data) |
198 | { | |
7ed20e1a | 199 | if (!valid_signal(data)) |
5ecfbae0 | 200 | return -EIO; |
1da177e4 LT |
201 | |
202 | /* Architecture-specific hardware disable .. */ | |
203 | ptrace_disable(child); | |
204 | ||
1da177e4 | 205 | write_lock_irq(&tasklist_lock); |
5ecfbae0 ON |
206 | if (child->ptrace) |
207 | __ptrace_detach(child, data); | |
1da177e4 LT |
208 | write_unlock_irq(&tasklist_lock); |
209 | ||
210 | return 0; | |
211 | } | |
212 | ||
213 | /* | |
214 | * Access another process' address space. | |
215 | * Source/target buffer must be kernel space, | |
216 | * Do not walk the page table directly, use get_user_pages | |
217 | */ | |
218 | ||
219 | int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) | |
220 | { | |
221 | struct mm_struct *mm; | |
222 | struct vm_area_struct *vma; | |
223 | struct page *page; | |
224 | void *old_buf = buf; | |
225 | ||
226 | mm = get_task_mm(tsk); | |
227 | if (!mm) | |
228 | return 0; | |
229 | ||
230 | down_read(&mm->mmap_sem); | |
231 | /* ignore errors, just check how much was sucessfully transfered */ | |
232 | while (len) { | |
233 | int bytes, ret, offset; | |
234 | void *maddr; | |
235 | ||
236 | ret = get_user_pages(tsk, mm, addr, 1, | |
237 | write, 1, &page, &vma); | |
238 | if (ret <= 0) | |
239 | break; | |
240 | ||
241 | bytes = len; | |
242 | offset = addr & (PAGE_SIZE-1); | |
243 | if (bytes > PAGE_SIZE-offset) | |
244 | bytes = PAGE_SIZE-offset; | |
245 | ||
246 | maddr = kmap(page); | |
247 | if (write) { | |
248 | copy_to_user_page(vma, page, addr, | |
249 | maddr + offset, buf, bytes); | |
16bf1348 | 250 | set_page_dirty_lock(page); |
1da177e4 LT |
251 | } else { |
252 | copy_from_user_page(vma, page, addr, | |
253 | buf, maddr + offset, bytes); | |
254 | } | |
255 | kunmap(page); | |
256 | page_cache_release(page); | |
257 | len -= bytes; | |
258 | buf += bytes; | |
259 | addr += bytes; | |
260 | } | |
261 | up_read(&mm->mmap_sem); | |
262 | mmput(mm); | |
263 | ||
264 | return buf - old_buf; | |
265 | } | |
266 | ||
267 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) | |
268 | { | |
269 | int copied = 0; | |
270 | ||
271 | while (len > 0) { | |
272 | char buf[128]; | |
273 | int this_len, retval; | |
274 | ||
275 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
276 | retval = access_process_vm(tsk, src, buf, this_len, 0); | |
277 | if (!retval) { | |
278 | if (copied) | |
279 | break; | |
280 | return -EIO; | |
281 | } | |
282 | if (copy_to_user(dst, buf, retval)) | |
283 | return -EFAULT; | |
284 | copied += retval; | |
285 | src += retval; | |
286 | dst += retval; | |
287 | len -= retval; | |
288 | } | |
289 | return copied; | |
290 | } | |
291 | ||
292 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) | |
293 | { | |
294 | int copied = 0; | |
295 | ||
296 | while (len > 0) { | |
297 | char buf[128]; | |
298 | int this_len, retval; | |
299 | ||
300 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
301 | if (copy_from_user(buf, src, this_len)) | |
302 | return -EFAULT; | |
303 | retval = access_process_vm(tsk, dst, buf, this_len, 1); | |
304 | if (!retval) { | |
305 | if (copied) | |
306 | break; | |
307 | return -EIO; | |
308 | } | |
309 | copied += retval; | |
310 | src += retval; | |
311 | dst += retval; | |
312 | len -= retval; | |
313 | } | |
314 | return copied; | |
315 | } | |
316 | ||
317 | static int ptrace_setoptions(struct task_struct *child, long data) | |
318 | { | |
319 | child->ptrace &= ~PT_TRACE_MASK; | |
320 | ||
321 | if (data & PTRACE_O_TRACESYSGOOD) | |
322 | child->ptrace |= PT_TRACESYSGOOD; | |
323 | ||
324 | if (data & PTRACE_O_TRACEFORK) | |
325 | child->ptrace |= PT_TRACE_FORK; | |
326 | ||
327 | if (data & PTRACE_O_TRACEVFORK) | |
328 | child->ptrace |= PT_TRACE_VFORK; | |
329 | ||
330 | if (data & PTRACE_O_TRACECLONE) | |
331 | child->ptrace |= PT_TRACE_CLONE; | |
332 | ||
333 | if (data & PTRACE_O_TRACEEXEC) | |
334 | child->ptrace |= PT_TRACE_EXEC; | |
335 | ||
336 | if (data & PTRACE_O_TRACEVFORKDONE) | |
337 | child->ptrace |= PT_TRACE_VFORK_DONE; | |
338 | ||
339 | if (data & PTRACE_O_TRACEEXIT) | |
340 | child->ptrace |= PT_TRACE_EXIT; | |
341 | ||
342 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; | |
343 | } | |
344 | ||
345 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) | |
346 | { | |
347 | siginfo_t lastinfo; | |
348 | int error = -ESRCH; | |
349 | ||
350 | read_lock(&tasklist_lock); | |
351 | if (likely(child->sighand != NULL)) { | |
352 | error = -EINVAL; | |
353 | spin_lock_irq(&child->sighand->siglock); | |
354 | if (likely(child->last_siginfo != NULL)) { | |
355 | lastinfo = *child->last_siginfo; | |
356 | error = 0; | |
357 | } | |
358 | spin_unlock_irq(&child->sighand->siglock); | |
359 | } | |
360 | read_unlock(&tasklist_lock); | |
361 | if (!error) | |
362 | return copy_siginfo_to_user(data, &lastinfo); | |
363 | return error; | |
364 | } | |
365 | ||
366 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) | |
367 | { | |
368 | siginfo_t newinfo; | |
369 | int error = -ESRCH; | |
370 | ||
371 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) | |
372 | return -EFAULT; | |
373 | ||
374 | read_lock(&tasklist_lock); | |
375 | if (likely(child->sighand != NULL)) { | |
376 | error = -EINVAL; | |
377 | spin_lock_irq(&child->sighand->siglock); | |
378 | if (likely(child->last_siginfo != NULL)) { | |
379 | *child->last_siginfo = newinfo; | |
380 | error = 0; | |
381 | } | |
382 | spin_unlock_irq(&child->sighand->siglock); | |
383 | } | |
384 | read_unlock(&tasklist_lock); | |
385 | return error; | |
386 | } | |
387 | ||
388 | int ptrace_request(struct task_struct *child, long request, | |
389 | long addr, long data) | |
390 | { | |
391 | int ret = -EIO; | |
392 | ||
393 | switch (request) { | |
394 | #ifdef PTRACE_OLDSETOPTIONS | |
395 | case PTRACE_OLDSETOPTIONS: | |
396 | #endif | |
397 | case PTRACE_SETOPTIONS: | |
398 | ret = ptrace_setoptions(child, data); | |
399 | break; | |
400 | case PTRACE_GETEVENTMSG: | |
401 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); | |
402 | break; | |
403 | case PTRACE_GETSIGINFO: | |
404 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); | |
405 | break; | |
406 | case PTRACE_SETSIGINFO: | |
407 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); | |
408 | break; | |
409 | default: | |
410 | break; | |
411 | } | |
412 | ||
413 | return ret; | |
414 | } | |
481bed45 | 415 | |
6b9c7ed8 CH |
416 | /** |
417 | * ptrace_traceme -- helper for PTRACE_TRACEME | |
418 | * | |
419 | * Performs checks and sets PT_PTRACED. | |
420 | * Should be used by all ptrace implementations for PTRACE_TRACEME. | |
421 | */ | |
422 | int ptrace_traceme(void) | |
481bed45 | 423 | { |
481bed45 CH |
424 | int ret; |
425 | ||
426 | /* | |
6b9c7ed8 CH |
427 | * Are we already being traced? |
428 | */ | |
429 | if (current->ptrace & PT_PTRACED) | |
430 | return -EPERM; | |
431 | ret = security_ptrace(current->parent, current); | |
432 | if (ret) | |
433 | return -EPERM; | |
434 | /* | |
435 | * Set the ptrace bit in the process ptrace flags. | |
481bed45 | 436 | */ |
6b9c7ed8 CH |
437 | current->ptrace |= PT_PTRACED; |
438 | return 0; | |
439 | } | |
481bed45 | 440 | |
6b9c7ed8 CH |
441 | /** |
442 | * ptrace_get_task_struct -- grab a task struct reference for ptrace | |
443 | * @pid: process id to grab a task_struct reference of | |
444 | * | |
445 | * This function is a helper for ptrace implementations. It checks | |
446 | * permissions and then grabs a task struct for use of the actual | |
447 | * ptrace implementation. | |
448 | * | |
449 | * Returns the task_struct for @pid or an ERR_PTR() on failure. | |
450 | */ | |
451 | struct task_struct *ptrace_get_task_struct(pid_t pid) | |
452 | { | |
453 | struct task_struct *child; | |
481bed45 CH |
454 | |
455 | /* | |
6b9c7ed8 | 456 | * Tracing init is not allowed. |
481bed45 CH |
457 | */ |
458 | if (pid == 1) | |
6b9c7ed8 | 459 | return ERR_PTR(-EPERM); |
481bed45 | 460 | |
481bed45 CH |
461 | read_lock(&tasklist_lock); |
462 | child = find_task_by_pid(pid); | |
463 | if (child) | |
464 | get_task_struct(child); | |
465 | read_unlock(&tasklist_lock); | |
466 | if (!child) | |
6b9c7ed8 CH |
467 | return ERR_PTR(-ESRCH); |
468 | return child; | |
481bed45 CH |
469 | } |
470 | ||
6b9c7ed8 | 471 | #ifndef __ARCH_SYS_PTRACE |
481bed45 CH |
472 | asmlinkage long sys_ptrace(long request, long pid, long addr, long data) |
473 | { | |
474 | struct task_struct *child; | |
475 | long ret; | |
476 | ||
477 | /* | |
478 | * This lock_kernel fixes a subtle race with suid exec | |
479 | */ | |
480 | lock_kernel(); | |
6b9c7ed8 CH |
481 | if (request == PTRACE_TRACEME) { |
482 | ret = ptrace_traceme(); | |
481bed45 | 483 | goto out; |
6b9c7ed8 CH |
484 | } |
485 | ||
486 | child = ptrace_get_task_struct(pid); | |
487 | if (IS_ERR(child)) { | |
488 | ret = PTR_ERR(child); | |
489 | goto out; | |
490 | } | |
481bed45 CH |
491 | |
492 | if (request == PTRACE_ATTACH) { | |
493 | ret = ptrace_attach(child); | |
005f18df | 494 | goto out_put_task_struct; |
481bed45 CH |
495 | } |
496 | ||
497 | ret = ptrace_check_attach(child, request == PTRACE_KILL); | |
498 | if (ret < 0) | |
499 | goto out_put_task_struct; | |
500 | ||
501 | ret = arch_ptrace(child, request, addr, data); | |
502 | if (ret < 0) | |
503 | goto out_put_task_struct; | |
504 | ||
505 | out_put_task_struct: | |
506 | put_task_struct(child); | |
507 | out: | |
508 | unlock_kernel(); | |
509 | return ret; | |
510 | } | |
511 | #endif /* __ARCH_SYS_PTRACE */ |