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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 | ||
10 | #include <linux/module.h> | |
11 | #include <linux/sched.h> | |
12 | #include <linux/errno.h> | |
13 | #include <linux/mm.h> | |
14 | #include <linux/highmem.h> | |
15 | #include <linux/pagemap.h> | |
16 | #include <linux/smp_lock.h> | |
17 | #include <linux/ptrace.h> | |
18 | #include <linux/security.h> | |
7ed20e1a | 19 | #include <linux/signal.h> |
1da177e4 LT |
20 | |
21 | #include <asm/pgtable.h> | |
22 | #include <asm/uaccess.h> | |
23 | ||
24 | /* | |
25 | * ptrace a task: make the debugger its new parent and | |
26 | * move it to the ptrace list. | |
27 | * | |
28 | * Must be called with the tasklist lock write-held. | |
29 | */ | |
30 | void __ptrace_link(task_t *child, task_t *new_parent) | |
31 | { | |
32 | if (!list_empty(&child->ptrace_list)) | |
33 | BUG(); | |
34 | if (child->parent == new_parent) | |
35 | return; | |
36 | list_add(&child->ptrace_list, &child->parent->ptrace_children); | |
37 | REMOVE_LINKS(child); | |
38 | child->parent = new_parent; | |
39 | SET_LINKS(child); | |
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 | } | |
30e0fca6 AA |
59 | if (child->signal->flags & SIGNAL_GROUP_EXIT) { |
60 | sigaddset(&child->pending.signal, SIGKILL); | |
61 | signal_wake_up(child, 1); | |
62 | } | |
1da177e4 LT |
63 | spin_unlock(&child->sighand->siglock); |
64 | } | |
65 | ||
66 | /* | |
67 | * unptrace a task: move it back to its original parent and | |
68 | * remove it from the ptrace list. | |
69 | * | |
70 | * Must be called with the tasklist lock write-held. | |
71 | */ | |
72 | void __ptrace_unlink(task_t *child) | |
73 | { | |
74 | if (!child->ptrace) | |
75 | BUG(); | |
76 | child->ptrace = 0; | |
77 | if (!list_empty(&child->ptrace_list)) { | |
78 | list_del_init(&child->ptrace_list); | |
79 | REMOVE_LINKS(child); | |
80 | child->parent = child->real_parent; | |
81 | SET_LINKS(child); | |
82 | } | |
83 | ||
30e0fca6 | 84 | ptrace_untrace(child); |
1da177e4 LT |
85 | } |
86 | ||
87 | /* | |
88 | * Check that we have indeed attached to the thing.. | |
89 | */ | |
90 | int ptrace_check_attach(struct task_struct *child, int kill) | |
91 | { | |
92 | int ret = -ESRCH; | |
93 | ||
94 | /* | |
95 | * We take the read lock around doing both checks to close a | |
96 | * possible race where someone else was tracing our child and | |
97 | * detached between these two checks. After this locked check, | |
98 | * we are sure that this is our traced child and that can only | |
99 | * be changed by us so it's not changing right after this. | |
100 | */ | |
101 | read_lock(&tasklist_lock); | |
102 | if ((child->ptrace & PT_PTRACED) && child->parent == current && | |
103 | (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) | |
104 | && child->signal != NULL) { | |
105 | ret = 0; | |
106 | spin_lock_irq(&child->sighand->siglock); | |
107 | if (child->state == TASK_STOPPED) { | |
108 | child->state = TASK_TRACED; | |
109 | } else if (child->state != TASK_TRACED && !kill) { | |
110 | ret = -ESRCH; | |
111 | } | |
112 | spin_unlock_irq(&child->sighand->siglock); | |
113 | } | |
114 | read_unlock(&tasklist_lock); | |
115 | ||
116 | if (!ret && !kill) { | |
117 | wait_task_inactive(child); | |
118 | } | |
119 | ||
120 | /* All systems go.. */ | |
121 | return ret; | |
122 | } | |
123 | ||
ab8d11be MS |
124 | static int may_attach(struct task_struct *task) |
125 | { | |
126 | if (!task->mm) | |
127 | return -EPERM; | |
128 | if (((current->uid != task->euid) || | |
129 | (current->uid != task->suid) || | |
130 | (current->uid != task->uid) || | |
131 | (current->gid != task->egid) || | |
132 | (current->gid != task->sgid) || | |
133 | (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) | |
134 | return -EPERM; | |
135 | smp_rmb(); | |
136 | if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) | |
137 | return -EPERM; | |
138 | ||
139 | return security_ptrace(current, task); | |
140 | } | |
141 | ||
142 | int ptrace_may_attach(struct task_struct *task) | |
143 | { | |
144 | int err; | |
145 | task_lock(task); | |
146 | err = may_attach(task); | |
147 | task_unlock(task); | |
148 | return !err; | |
149 | } | |
150 | ||
1da177e4 LT |
151 | int ptrace_attach(struct task_struct *task) |
152 | { | |
153 | int retval; | |
154 | task_lock(task); | |
155 | retval = -EPERM; | |
156 | if (task->pid <= 1) | |
157 | goto bad; | |
28d838cc | 158 | if (task->tgid == current->tgid) |
1da177e4 | 159 | goto bad; |
1da177e4 LT |
160 | /* the same process cannot be attached many times */ |
161 | if (task->ptrace & PT_PTRACED) | |
162 | goto bad; | |
ab8d11be | 163 | retval = may_attach(task); |
1da177e4 LT |
164 | if (retval) |
165 | goto bad; | |
166 | ||
167 | /* Go */ | |
168 | task->ptrace |= PT_PTRACED | ((task->real_parent != current) | |
169 | ? PT_ATTACHED : 0); | |
170 | if (capable(CAP_SYS_PTRACE)) | |
171 | task->ptrace |= PT_PTRACE_CAP; | |
172 | task_unlock(task); | |
173 | ||
174 | write_lock_irq(&tasklist_lock); | |
175 | __ptrace_link(task, current); | |
176 | write_unlock_irq(&tasklist_lock); | |
177 | ||
178 | force_sig_specific(SIGSTOP, task); | |
179 | return 0; | |
180 | ||
181 | bad: | |
182 | task_unlock(task); | |
183 | return retval; | |
184 | } | |
185 | ||
186 | int ptrace_detach(struct task_struct *child, unsigned int data) | |
187 | { | |
7ed20e1a | 188 | if (!valid_signal(data)) |
1da177e4 LT |
189 | return -EIO; |
190 | ||
191 | /* Architecture-specific hardware disable .. */ | |
192 | ptrace_disable(child); | |
193 | ||
194 | /* .. re-parent .. */ | |
195 | child->exit_code = data; | |
196 | ||
197 | write_lock_irq(&tasklist_lock); | |
198 | __ptrace_unlink(child); | |
199 | /* .. and wake it up. */ | |
200 | if (child->exit_state != EXIT_ZOMBIE) | |
201 | wake_up_process(child); | |
202 | write_unlock_irq(&tasklist_lock); | |
203 | ||
204 | return 0; | |
205 | } | |
206 | ||
207 | /* | |
208 | * Access another process' address space. | |
209 | * Source/target buffer must be kernel space, | |
210 | * Do not walk the page table directly, use get_user_pages | |
211 | */ | |
212 | ||
213 | int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) | |
214 | { | |
215 | struct mm_struct *mm; | |
216 | struct vm_area_struct *vma; | |
217 | struct page *page; | |
218 | void *old_buf = buf; | |
219 | ||
220 | mm = get_task_mm(tsk); | |
221 | if (!mm) | |
222 | return 0; | |
223 | ||
224 | down_read(&mm->mmap_sem); | |
225 | /* ignore errors, just check how much was sucessfully transfered */ | |
226 | while (len) { | |
227 | int bytes, ret, offset; | |
228 | void *maddr; | |
229 | ||
230 | ret = get_user_pages(tsk, mm, addr, 1, | |
231 | write, 1, &page, &vma); | |
232 | if (ret <= 0) | |
233 | break; | |
234 | ||
235 | bytes = len; | |
236 | offset = addr & (PAGE_SIZE-1); | |
237 | if (bytes > PAGE_SIZE-offset) | |
238 | bytes = PAGE_SIZE-offset; | |
239 | ||
240 | maddr = kmap(page); | |
241 | if (write) { | |
242 | copy_to_user_page(vma, page, addr, | |
243 | maddr + offset, buf, bytes); | |
5bd0190b DG |
244 | if (!PageCompound(page)) |
245 | set_page_dirty_lock(page); | |
1da177e4 LT |
246 | } else { |
247 | copy_from_user_page(vma, page, addr, | |
248 | buf, maddr + offset, bytes); | |
249 | } | |
250 | kunmap(page); | |
251 | page_cache_release(page); | |
252 | len -= bytes; | |
253 | buf += bytes; | |
254 | addr += bytes; | |
255 | } | |
256 | up_read(&mm->mmap_sem); | |
257 | mmput(mm); | |
258 | ||
259 | return buf - old_buf; | |
260 | } | |
261 | ||
262 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) | |
263 | { | |
264 | int copied = 0; | |
265 | ||
266 | while (len > 0) { | |
267 | char buf[128]; | |
268 | int this_len, retval; | |
269 | ||
270 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
271 | retval = access_process_vm(tsk, src, buf, this_len, 0); | |
272 | if (!retval) { | |
273 | if (copied) | |
274 | break; | |
275 | return -EIO; | |
276 | } | |
277 | if (copy_to_user(dst, buf, retval)) | |
278 | return -EFAULT; | |
279 | copied += retval; | |
280 | src += retval; | |
281 | dst += retval; | |
282 | len -= retval; | |
283 | } | |
284 | return copied; | |
285 | } | |
286 | ||
287 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) | |
288 | { | |
289 | int copied = 0; | |
290 | ||
291 | while (len > 0) { | |
292 | char buf[128]; | |
293 | int this_len, retval; | |
294 | ||
295 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
296 | if (copy_from_user(buf, src, this_len)) | |
297 | return -EFAULT; | |
298 | retval = access_process_vm(tsk, dst, buf, this_len, 1); | |
299 | if (!retval) { | |
300 | if (copied) | |
301 | break; | |
302 | return -EIO; | |
303 | } | |
304 | copied += retval; | |
305 | src += retval; | |
306 | dst += retval; | |
307 | len -= retval; | |
308 | } | |
309 | return copied; | |
310 | } | |
311 | ||
312 | static int ptrace_setoptions(struct task_struct *child, long data) | |
313 | { | |
314 | child->ptrace &= ~PT_TRACE_MASK; | |
315 | ||
316 | if (data & PTRACE_O_TRACESYSGOOD) | |
317 | child->ptrace |= PT_TRACESYSGOOD; | |
318 | ||
319 | if (data & PTRACE_O_TRACEFORK) | |
320 | child->ptrace |= PT_TRACE_FORK; | |
321 | ||
322 | if (data & PTRACE_O_TRACEVFORK) | |
323 | child->ptrace |= PT_TRACE_VFORK; | |
324 | ||
325 | if (data & PTRACE_O_TRACECLONE) | |
326 | child->ptrace |= PT_TRACE_CLONE; | |
327 | ||
328 | if (data & PTRACE_O_TRACEEXEC) | |
329 | child->ptrace |= PT_TRACE_EXEC; | |
330 | ||
331 | if (data & PTRACE_O_TRACEVFORKDONE) | |
332 | child->ptrace |= PT_TRACE_VFORK_DONE; | |
333 | ||
334 | if (data & PTRACE_O_TRACEEXIT) | |
335 | child->ptrace |= PT_TRACE_EXIT; | |
336 | ||
337 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; | |
338 | } | |
339 | ||
340 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) | |
341 | { | |
342 | siginfo_t lastinfo; | |
343 | int error = -ESRCH; | |
344 | ||
345 | read_lock(&tasklist_lock); | |
346 | if (likely(child->sighand != NULL)) { | |
347 | error = -EINVAL; | |
348 | spin_lock_irq(&child->sighand->siglock); | |
349 | if (likely(child->last_siginfo != NULL)) { | |
350 | lastinfo = *child->last_siginfo; | |
351 | error = 0; | |
352 | } | |
353 | spin_unlock_irq(&child->sighand->siglock); | |
354 | } | |
355 | read_unlock(&tasklist_lock); | |
356 | if (!error) | |
357 | return copy_siginfo_to_user(data, &lastinfo); | |
358 | return error; | |
359 | } | |
360 | ||
361 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) | |
362 | { | |
363 | siginfo_t newinfo; | |
364 | int error = -ESRCH; | |
365 | ||
366 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) | |
367 | return -EFAULT; | |
368 | ||
369 | read_lock(&tasklist_lock); | |
370 | if (likely(child->sighand != NULL)) { | |
371 | error = -EINVAL; | |
372 | spin_lock_irq(&child->sighand->siglock); | |
373 | if (likely(child->last_siginfo != NULL)) { | |
374 | *child->last_siginfo = newinfo; | |
375 | error = 0; | |
376 | } | |
377 | spin_unlock_irq(&child->sighand->siglock); | |
378 | } | |
379 | read_unlock(&tasklist_lock); | |
380 | return error; | |
381 | } | |
382 | ||
383 | int ptrace_request(struct task_struct *child, long request, | |
384 | long addr, long data) | |
385 | { | |
386 | int ret = -EIO; | |
387 | ||
388 | switch (request) { | |
389 | #ifdef PTRACE_OLDSETOPTIONS | |
390 | case PTRACE_OLDSETOPTIONS: | |
391 | #endif | |
392 | case PTRACE_SETOPTIONS: | |
393 | ret = ptrace_setoptions(child, data); | |
394 | break; | |
395 | case PTRACE_GETEVENTMSG: | |
396 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); | |
397 | break; | |
398 | case PTRACE_GETSIGINFO: | |
399 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); | |
400 | break; | |
401 | case PTRACE_SETSIGINFO: | |
402 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); | |
403 | break; | |
404 | default: | |
405 | break; | |
406 | } | |
407 | ||
408 | return ret; | |
409 | } | |
481bed45 CH |
410 | |
411 | #ifndef __ARCH_SYS_PTRACE | |
412 | static int ptrace_get_task_struct(long request, long pid, | |
413 | struct task_struct **childp) | |
414 | { | |
415 | struct task_struct *child; | |
416 | int ret; | |
417 | ||
418 | /* | |
419 | * Callers use child == NULL as an indication to exit early even | |
420 | * when the return value is 0, so make sure it is non-NULL here. | |
421 | */ | |
422 | *childp = NULL; | |
423 | ||
424 | if (request == PTRACE_TRACEME) { | |
425 | /* | |
426 | * Are we already being traced? | |
427 | */ | |
428 | if (current->ptrace & PT_PTRACED) | |
429 | return -EPERM; | |
430 | ret = security_ptrace(current->parent, current); | |
431 | if (ret) | |
432 | return -EPERM; | |
433 | /* | |
434 | * Set the ptrace bit in the process ptrace flags. | |
435 | */ | |
436 | current->ptrace |= PT_PTRACED; | |
437 | return 0; | |
438 | } | |
439 | ||
440 | /* | |
441 | * You may not mess with init | |
442 | */ | |
443 | if (pid == 1) | |
444 | return -EPERM; | |
445 | ||
446 | ret = -ESRCH; | |
447 | read_lock(&tasklist_lock); | |
448 | child = find_task_by_pid(pid); | |
449 | if (child) | |
450 | get_task_struct(child); | |
451 | read_unlock(&tasklist_lock); | |
452 | if (!child) | |
453 | return -ESRCH; | |
454 | ||
455 | *childp = child; | |
456 | return 0; | |
457 | } | |
458 | ||
459 | asmlinkage long sys_ptrace(long request, long pid, long addr, long data) | |
460 | { | |
461 | struct task_struct *child; | |
462 | long ret; | |
463 | ||
464 | /* | |
465 | * This lock_kernel fixes a subtle race with suid exec | |
466 | */ | |
467 | lock_kernel(); | |
468 | ret = ptrace_get_task_struct(request, pid, &child); | |
469 | if (!child) | |
470 | goto out; | |
471 | ||
472 | if (request == PTRACE_ATTACH) { | |
473 | ret = ptrace_attach(child); | |
005f18df | 474 | goto out_put_task_struct; |
481bed45 CH |
475 | } |
476 | ||
477 | ret = ptrace_check_attach(child, request == PTRACE_KILL); | |
478 | if (ret < 0) | |
479 | goto out_put_task_struct; | |
480 | ||
481 | ret = arch_ptrace(child, request, addr, data); | |
482 | if (ret < 0) | |
483 | goto out_put_task_struct; | |
484 | ||
485 | out_put_task_struct: | |
486 | put_task_struct(child); | |
487 | out: | |
488 | unlock_kernel(); | |
489 | return ret; | |
490 | } | |
491 | #endif /* __ARCH_SYS_PTRACE */ |