]>
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); | |
38 | REMOVE_LINKS(child); | |
39 | child->parent = new_parent; | |
40 | SET_LINKS(child); | |
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 | { | |
75 | if (!child->ptrace) | |
76 | BUG(); | |
77 | child->ptrace = 0; | |
78 | if (!list_empty(&child->ptrace_list)) { | |
79 | list_del_init(&child->ptrace_list); | |
80 | REMOVE_LINKS(child); | |
81 | child->parent = child->real_parent; | |
82 | SET_LINKS(child); | |
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 | ||
187 | int ptrace_detach(struct task_struct *child, unsigned int data) | |
188 | { | |
7ed20e1a | 189 | if (!valid_signal(data)) |
1da177e4 LT |
190 | return -EIO; |
191 | ||
192 | /* Architecture-specific hardware disable .. */ | |
193 | ptrace_disable(child); | |
194 | ||
195 | /* .. re-parent .. */ | |
196 | child->exit_code = data; | |
197 | ||
198 | write_lock_irq(&tasklist_lock); | |
199 | __ptrace_unlink(child); | |
200 | /* .. and wake it up. */ | |
201 | if (child->exit_state != EXIT_ZOMBIE) | |
202 | wake_up_process(child); | |
203 | write_unlock_irq(&tasklist_lock); | |
204 | ||
205 | return 0; | |
206 | } | |
207 | ||
208 | /* | |
209 | * Access another process' address space. | |
210 | * Source/target buffer must be kernel space, | |
211 | * Do not walk the page table directly, use get_user_pages | |
212 | */ | |
213 | ||
214 | int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) | |
215 | { | |
216 | struct mm_struct *mm; | |
217 | struct vm_area_struct *vma; | |
218 | struct page *page; | |
219 | void *old_buf = buf; | |
220 | ||
221 | mm = get_task_mm(tsk); | |
222 | if (!mm) | |
223 | return 0; | |
224 | ||
225 | down_read(&mm->mmap_sem); | |
226 | /* ignore errors, just check how much was sucessfully transfered */ | |
227 | while (len) { | |
228 | int bytes, ret, offset; | |
229 | void *maddr; | |
230 | ||
231 | ret = get_user_pages(tsk, mm, addr, 1, | |
232 | write, 1, &page, &vma); | |
233 | if (ret <= 0) | |
234 | break; | |
235 | ||
236 | bytes = len; | |
237 | offset = addr & (PAGE_SIZE-1); | |
238 | if (bytes > PAGE_SIZE-offset) | |
239 | bytes = PAGE_SIZE-offset; | |
240 | ||
241 | maddr = kmap(page); | |
242 | if (write) { | |
243 | copy_to_user_page(vma, page, addr, | |
244 | maddr + offset, buf, bytes); | |
5bd0190b DG |
245 | if (!PageCompound(page)) |
246 | set_page_dirty_lock(page); | |
1da177e4 LT |
247 | } else { |
248 | copy_from_user_page(vma, page, addr, | |
249 | buf, maddr + offset, bytes); | |
250 | } | |
251 | kunmap(page); | |
252 | page_cache_release(page); | |
253 | len -= bytes; | |
254 | buf += bytes; | |
255 | addr += bytes; | |
256 | } | |
257 | up_read(&mm->mmap_sem); | |
258 | mmput(mm); | |
259 | ||
260 | return buf - old_buf; | |
261 | } | |
262 | ||
263 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) | |
264 | { | |
265 | int copied = 0; | |
266 | ||
267 | while (len > 0) { | |
268 | char buf[128]; | |
269 | int this_len, retval; | |
270 | ||
271 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
272 | retval = access_process_vm(tsk, src, buf, this_len, 0); | |
273 | if (!retval) { | |
274 | if (copied) | |
275 | break; | |
276 | return -EIO; | |
277 | } | |
278 | if (copy_to_user(dst, buf, retval)) | |
279 | return -EFAULT; | |
280 | copied += retval; | |
281 | src += retval; | |
282 | dst += retval; | |
283 | len -= retval; | |
284 | } | |
285 | return copied; | |
286 | } | |
287 | ||
288 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) | |
289 | { | |
290 | int copied = 0; | |
291 | ||
292 | while (len > 0) { | |
293 | char buf[128]; | |
294 | int this_len, retval; | |
295 | ||
296 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
297 | if (copy_from_user(buf, src, this_len)) | |
298 | return -EFAULT; | |
299 | retval = access_process_vm(tsk, dst, buf, this_len, 1); | |
300 | if (!retval) { | |
301 | if (copied) | |
302 | break; | |
303 | return -EIO; | |
304 | } | |
305 | copied += retval; | |
306 | src += retval; | |
307 | dst += retval; | |
308 | len -= retval; | |
309 | } | |
310 | return copied; | |
311 | } | |
312 | ||
313 | static int ptrace_setoptions(struct task_struct *child, long data) | |
314 | { | |
315 | child->ptrace &= ~PT_TRACE_MASK; | |
316 | ||
317 | if (data & PTRACE_O_TRACESYSGOOD) | |
318 | child->ptrace |= PT_TRACESYSGOOD; | |
319 | ||
320 | if (data & PTRACE_O_TRACEFORK) | |
321 | child->ptrace |= PT_TRACE_FORK; | |
322 | ||
323 | if (data & PTRACE_O_TRACEVFORK) | |
324 | child->ptrace |= PT_TRACE_VFORK; | |
325 | ||
326 | if (data & PTRACE_O_TRACECLONE) | |
327 | child->ptrace |= PT_TRACE_CLONE; | |
328 | ||
329 | if (data & PTRACE_O_TRACEEXEC) | |
330 | child->ptrace |= PT_TRACE_EXEC; | |
331 | ||
332 | if (data & PTRACE_O_TRACEVFORKDONE) | |
333 | child->ptrace |= PT_TRACE_VFORK_DONE; | |
334 | ||
335 | if (data & PTRACE_O_TRACEEXIT) | |
336 | child->ptrace |= PT_TRACE_EXIT; | |
337 | ||
338 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; | |
339 | } | |
340 | ||
341 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) | |
342 | { | |
343 | siginfo_t lastinfo; | |
344 | int error = -ESRCH; | |
345 | ||
346 | read_lock(&tasklist_lock); | |
347 | if (likely(child->sighand != NULL)) { | |
348 | error = -EINVAL; | |
349 | spin_lock_irq(&child->sighand->siglock); | |
350 | if (likely(child->last_siginfo != NULL)) { | |
351 | lastinfo = *child->last_siginfo; | |
352 | error = 0; | |
353 | } | |
354 | spin_unlock_irq(&child->sighand->siglock); | |
355 | } | |
356 | read_unlock(&tasklist_lock); | |
357 | if (!error) | |
358 | return copy_siginfo_to_user(data, &lastinfo); | |
359 | return error; | |
360 | } | |
361 | ||
362 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) | |
363 | { | |
364 | siginfo_t newinfo; | |
365 | int error = -ESRCH; | |
366 | ||
367 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) | |
368 | return -EFAULT; | |
369 | ||
370 | read_lock(&tasklist_lock); | |
371 | if (likely(child->sighand != NULL)) { | |
372 | error = -EINVAL; | |
373 | spin_lock_irq(&child->sighand->siglock); | |
374 | if (likely(child->last_siginfo != NULL)) { | |
375 | *child->last_siginfo = newinfo; | |
376 | error = 0; | |
377 | } | |
378 | spin_unlock_irq(&child->sighand->siglock); | |
379 | } | |
380 | read_unlock(&tasklist_lock); | |
381 | return error; | |
382 | } | |
383 | ||
384 | int ptrace_request(struct task_struct *child, long request, | |
385 | long addr, long data) | |
386 | { | |
387 | int ret = -EIO; | |
388 | ||
389 | switch (request) { | |
390 | #ifdef PTRACE_OLDSETOPTIONS | |
391 | case PTRACE_OLDSETOPTIONS: | |
392 | #endif | |
393 | case PTRACE_SETOPTIONS: | |
394 | ret = ptrace_setoptions(child, data); | |
395 | break; | |
396 | case PTRACE_GETEVENTMSG: | |
397 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); | |
398 | break; | |
399 | case PTRACE_GETSIGINFO: | |
400 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); | |
401 | break; | |
402 | case PTRACE_SETSIGINFO: | |
403 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); | |
404 | break; | |
405 | default: | |
406 | break; | |
407 | } | |
408 | ||
409 | return ret; | |
410 | } | |
481bed45 | 411 | |
6b9c7ed8 CH |
412 | /** |
413 | * ptrace_traceme -- helper for PTRACE_TRACEME | |
414 | * | |
415 | * Performs checks and sets PT_PTRACED. | |
416 | * Should be used by all ptrace implementations for PTRACE_TRACEME. | |
417 | */ | |
418 | int ptrace_traceme(void) | |
481bed45 | 419 | { |
481bed45 CH |
420 | int ret; |
421 | ||
422 | /* | |
6b9c7ed8 CH |
423 | * Are we already being traced? |
424 | */ | |
425 | if (current->ptrace & PT_PTRACED) | |
426 | return -EPERM; | |
427 | ret = security_ptrace(current->parent, current); | |
428 | if (ret) | |
429 | return -EPERM; | |
430 | /* | |
431 | * Set the ptrace bit in the process ptrace flags. | |
481bed45 | 432 | */ |
6b9c7ed8 CH |
433 | current->ptrace |= PT_PTRACED; |
434 | return 0; | |
435 | } | |
481bed45 | 436 | |
6b9c7ed8 CH |
437 | /** |
438 | * ptrace_get_task_struct -- grab a task struct reference for ptrace | |
439 | * @pid: process id to grab a task_struct reference of | |
440 | * | |
441 | * This function is a helper for ptrace implementations. It checks | |
442 | * permissions and then grabs a task struct for use of the actual | |
443 | * ptrace implementation. | |
444 | * | |
445 | * Returns the task_struct for @pid or an ERR_PTR() on failure. | |
446 | */ | |
447 | struct task_struct *ptrace_get_task_struct(pid_t pid) | |
448 | { | |
449 | struct task_struct *child; | |
481bed45 CH |
450 | |
451 | /* | |
6b9c7ed8 | 452 | * Tracing init is not allowed. |
481bed45 CH |
453 | */ |
454 | if (pid == 1) | |
6b9c7ed8 | 455 | return ERR_PTR(-EPERM); |
481bed45 | 456 | |
481bed45 CH |
457 | read_lock(&tasklist_lock); |
458 | child = find_task_by_pid(pid); | |
459 | if (child) | |
460 | get_task_struct(child); | |
461 | read_unlock(&tasklist_lock); | |
462 | if (!child) | |
6b9c7ed8 CH |
463 | return ERR_PTR(-ESRCH); |
464 | return child; | |
481bed45 CH |
465 | } |
466 | ||
6b9c7ed8 | 467 | #ifndef __ARCH_SYS_PTRACE |
481bed45 CH |
468 | asmlinkage long sys_ptrace(long request, long pid, long addr, long data) |
469 | { | |
470 | struct task_struct *child; | |
471 | long ret; | |
472 | ||
473 | /* | |
474 | * This lock_kernel fixes a subtle race with suid exec | |
475 | */ | |
476 | lock_kernel(); | |
6b9c7ed8 CH |
477 | if (request == PTRACE_TRACEME) { |
478 | ret = ptrace_traceme(); | |
481bed45 | 479 | goto out; |
6b9c7ed8 CH |
480 | } |
481 | ||
482 | child = ptrace_get_task_struct(pid); | |
483 | if (IS_ERR(child)) { | |
484 | ret = PTR_ERR(child); | |
485 | goto out; | |
486 | } | |
481bed45 CH |
487 | |
488 | if (request == PTRACE_ATTACH) { | |
489 | ret = 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 */ |