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> |
a5cb013d | 21 | #include <linux/audit.h> |
1da177e4 LT |
22 | |
23 | #include <asm/pgtable.h> | |
24 | #include <asm/uaccess.h> | |
25 | ||
26 | /* | |
27 | * ptrace a task: make the debugger its new parent and | |
28 | * move it to the ptrace list. | |
29 | * | |
30 | * Must be called with the tasklist lock write-held. | |
31 | */ | |
36c8b586 | 32 | void __ptrace_link(struct task_struct *child, struct task_struct *new_parent) |
1da177e4 | 33 | { |
524223ca | 34 | BUG_ON(!list_empty(&child->ptrace_list)); |
1da177e4 LT |
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 | */ | |
36c8b586 | 50 | void ptrace_untrace(struct task_struct *child) |
1da177e4 LT |
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 | } | |
60 | spin_unlock(&child->sighand->siglock); | |
61 | } | |
62 | ||
63 | /* | |
64 | * unptrace a task: move it back to its original parent and | |
65 | * remove it from the ptrace list. | |
66 | * | |
67 | * Must be called with the tasklist lock write-held. | |
68 | */ | |
36c8b586 | 69 | void __ptrace_unlink(struct task_struct *child) |
1da177e4 | 70 | { |
5ecfbae0 ON |
71 | BUG_ON(!child->ptrace); |
72 | ||
1da177e4 LT |
73 | child->ptrace = 0; |
74 | if (!list_empty(&child->ptrace_list)) { | |
75 | list_del_init(&child->ptrace_list); | |
9b678ece | 76 | remove_parent(child); |
1da177e4 | 77 | child->parent = child->real_parent; |
9b678ece | 78 | add_parent(child); |
1da177e4 LT |
79 | } |
80 | ||
e57a5059 RM |
81 | if (child->state == TASK_TRACED) |
82 | ptrace_untrace(child); | |
1da177e4 LT |
83 | } |
84 | ||
85 | /* | |
86 | * Check that we have indeed attached to the thing.. | |
87 | */ | |
88 | int ptrace_check_attach(struct task_struct *child, int kill) | |
89 | { | |
90 | int ret = -ESRCH; | |
91 | ||
92 | /* | |
93 | * We take the read lock around doing both checks to close a | |
94 | * possible race where someone else was tracing our child and | |
95 | * detached between these two checks. After this locked check, | |
96 | * we are sure that this is our traced child and that can only | |
97 | * be changed by us so it's not changing right after this. | |
98 | */ | |
99 | read_lock(&tasklist_lock); | |
100 | if ((child->ptrace & PT_PTRACED) && child->parent == current && | |
101 | (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) | |
102 | && child->signal != NULL) { | |
103 | ret = 0; | |
104 | spin_lock_irq(&child->sighand->siglock); | |
105 | if (child->state == TASK_STOPPED) { | |
106 | child->state = TASK_TRACED; | |
107 | } else if (child->state != TASK_TRACED && !kill) { | |
108 | ret = -ESRCH; | |
109 | } | |
110 | spin_unlock_irq(&child->sighand->siglock); | |
111 | } | |
112 | read_unlock(&tasklist_lock); | |
113 | ||
114 | if (!ret && !kill) { | |
115 | wait_task_inactive(child); | |
116 | } | |
117 | ||
118 | /* All systems go.. */ | |
119 | return ret; | |
120 | } | |
121 | ||
ab8d11be MS |
122 | static int may_attach(struct task_struct *task) |
123 | { | |
df26c40e EB |
124 | /* May we inspect the given task? |
125 | * This check is used both for attaching with ptrace | |
126 | * and for allowing access to sensitive information in /proc. | |
127 | * | |
128 | * ptrace_attach denies several cases that /proc allows | |
129 | * because setting up the necessary parent/child relationship | |
130 | * or halting the specified task is impossible. | |
131 | */ | |
132 | int dumpable = 0; | |
133 | /* Don't let security modules deny introspection */ | |
134 | if (task == current) | |
135 | return 0; | |
ab8d11be MS |
136 | if (((current->uid != task->euid) || |
137 | (current->uid != task->suid) || | |
138 | (current->uid != task->uid) || | |
139 | (current->gid != task->egid) || | |
140 | (current->gid != task->sgid) || | |
141 | (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) | |
142 | return -EPERM; | |
143 | smp_rmb(); | |
df26c40e EB |
144 | if (task->mm) |
145 | dumpable = task->mm->dumpable; | |
146 | if (!dumpable && !capable(CAP_SYS_PTRACE)) | |
ab8d11be MS |
147 | return -EPERM; |
148 | ||
149 | return security_ptrace(current, task); | |
150 | } | |
151 | ||
152 | int ptrace_may_attach(struct task_struct *task) | |
153 | { | |
154 | int err; | |
155 | task_lock(task); | |
156 | err = may_attach(task); | |
157 | task_unlock(task); | |
158 | return !err; | |
159 | } | |
160 | ||
1da177e4 LT |
161 | int ptrace_attach(struct task_struct *task) |
162 | { | |
163 | int retval; | |
6175ecfe | 164 | unsigned long flags; |
f5b40e36 | 165 | |
a5cb013d AV |
166 | audit_ptrace(task); |
167 | ||
1da177e4 LT |
168 | retval = -EPERM; |
169 | if (task->pid <= 1) | |
f5b40e36 | 170 | goto out; |
28d838cc | 171 | if (task->tgid == current->tgid) |
f5b40e36 LT |
172 | goto out; |
173 | ||
f358166a LT |
174 | repeat: |
175 | /* | |
176 | * Nasty, nasty. | |
177 | * | |
178 | * We want to hold both the task-lock and the | |
179 | * tasklist_lock for writing at the same time. | |
180 | * But that's against the rules (tasklist_lock | |
181 | * is taken for reading by interrupts on other | |
182 | * cpu's that may have task_lock). | |
183 | */ | |
f5b40e36 | 184 | task_lock(task); |
6175ecfe | 185 | if (!write_trylock_irqsave(&tasklist_lock, flags)) { |
f358166a LT |
186 | task_unlock(task); |
187 | do { | |
188 | cpu_relax(); | |
189 | } while (!write_can_lock(&tasklist_lock)); | |
190 | goto repeat; | |
191 | } | |
f5b40e36 | 192 | |
df26c40e EB |
193 | if (!task->mm) |
194 | goto bad; | |
1da177e4 LT |
195 | /* the same process cannot be attached many times */ |
196 | if (task->ptrace & PT_PTRACED) | |
197 | goto bad; | |
ab8d11be | 198 | retval = may_attach(task); |
1da177e4 LT |
199 | if (retval) |
200 | goto bad; | |
201 | ||
202 | /* Go */ | |
203 | task->ptrace |= PT_PTRACED | ((task->real_parent != current) | |
204 | ? PT_ATTACHED : 0); | |
205 | if (capable(CAP_SYS_PTRACE)) | |
206 | task->ptrace |= PT_PTRACE_CAP; | |
1da177e4 | 207 | |
1da177e4 | 208 | __ptrace_link(task, current); |
1da177e4 LT |
209 | |
210 | force_sig_specific(SIGSTOP, task); | |
1da177e4 LT |
211 | |
212 | bad: | |
6175ecfe | 213 | write_unlock_irqrestore(&tasklist_lock, flags); |
1da177e4 | 214 | task_unlock(task); |
f5b40e36 | 215 | out: |
1da177e4 LT |
216 | return retval; |
217 | } | |
218 | ||
d5f70c00 | 219 | static inline void __ptrace_detach(struct task_struct *child, unsigned int data) |
5ecfbae0 ON |
220 | { |
221 | child->exit_code = data; | |
222 | /* .. re-parent .. */ | |
223 | __ptrace_unlink(child); | |
224 | /* .. and wake it up. */ | |
225 | if (child->exit_state != EXIT_ZOMBIE) | |
226 | wake_up_process(child); | |
227 | } | |
228 | ||
1da177e4 LT |
229 | int ptrace_detach(struct task_struct *child, unsigned int data) |
230 | { | |
7ed20e1a | 231 | if (!valid_signal(data)) |
5ecfbae0 | 232 | return -EIO; |
1da177e4 LT |
233 | |
234 | /* Architecture-specific hardware disable .. */ | |
235 | ptrace_disable(child); | |
236 | ||
1da177e4 | 237 | write_lock_irq(&tasklist_lock); |
d5f70c00 | 238 | /* protect against de_thread()->release_task() */ |
5ecfbae0 ON |
239 | if (child->ptrace) |
240 | __ptrace_detach(child, data); | |
1da177e4 LT |
241 | write_unlock_irq(&tasklist_lock); |
242 | ||
243 | return 0; | |
244 | } | |
245 | ||
1da177e4 LT |
246 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) |
247 | { | |
248 | int copied = 0; | |
249 | ||
250 | while (len > 0) { | |
251 | char buf[128]; | |
252 | int this_len, retval; | |
253 | ||
254 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
255 | retval = access_process_vm(tsk, src, buf, this_len, 0); | |
256 | if (!retval) { | |
257 | if (copied) | |
258 | break; | |
259 | return -EIO; | |
260 | } | |
261 | if (copy_to_user(dst, buf, retval)) | |
262 | return -EFAULT; | |
263 | copied += retval; | |
264 | src += retval; | |
265 | dst += retval; | |
266 | len -= retval; | |
267 | } | |
268 | return copied; | |
269 | } | |
270 | ||
271 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) | |
272 | { | |
273 | int copied = 0; | |
274 | ||
275 | while (len > 0) { | |
276 | char buf[128]; | |
277 | int this_len, retval; | |
278 | ||
279 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
280 | if (copy_from_user(buf, src, this_len)) | |
281 | return -EFAULT; | |
282 | retval = access_process_vm(tsk, dst, buf, this_len, 1); | |
283 | if (!retval) { | |
284 | if (copied) | |
285 | break; | |
286 | return -EIO; | |
287 | } | |
288 | copied += retval; | |
289 | src += retval; | |
290 | dst += retval; | |
291 | len -= retval; | |
292 | } | |
293 | return copied; | |
294 | } | |
295 | ||
296 | static int ptrace_setoptions(struct task_struct *child, long data) | |
297 | { | |
298 | child->ptrace &= ~PT_TRACE_MASK; | |
299 | ||
300 | if (data & PTRACE_O_TRACESYSGOOD) | |
301 | child->ptrace |= PT_TRACESYSGOOD; | |
302 | ||
303 | if (data & PTRACE_O_TRACEFORK) | |
304 | child->ptrace |= PT_TRACE_FORK; | |
305 | ||
306 | if (data & PTRACE_O_TRACEVFORK) | |
307 | child->ptrace |= PT_TRACE_VFORK; | |
308 | ||
309 | if (data & PTRACE_O_TRACECLONE) | |
310 | child->ptrace |= PT_TRACE_CLONE; | |
311 | ||
312 | if (data & PTRACE_O_TRACEEXEC) | |
313 | child->ptrace |= PT_TRACE_EXEC; | |
314 | ||
315 | if (data & PTRACE_O_TRACEVFORKDONE) | |
316 | child->ptrace |= PT_TRACE_VFORK_DONE; | |
317 | ||
318 | if (data & PTRACE_O_TRACEEXIT) | |
319 | child->ptrace |= PT_TRACE_EXIT; | |
320 | ||
321 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; | |
322 | } | |
323 | ||
324 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) | |
325 | { | |
326 | siginfo_t lastinfo; | |
327 | int error = -ESRCH; | |
328 | ||
329 | read_lock(&tasklist_lock); | |
330 | if (likely(child->sighand != NULL)) { | |
331 | error = -EINVAL; | |
332 | spin_lock_irq(&child->sighand->siglock); | |
333 | if (likely(child->last_siginfo != NULL)) { | |
334 | lastinfo = *child->last_siginfo; | |
335 | error = 0; | |
336 | } | |
337 | spin_unlock_irq(&child->sighand->siglock); | |
338 | } | |
339 | read_unlock(&tasklist_lock); | |
340 | if (!error) | |
341 | return copy_siginfo_to_user(data, &lastinfo); | |
342 | return error; | |
343 | } | |
344 | ||
345 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) | |
346 | { | |
347 | siginfo_t newinfo; | |
348 | int error = -ESRCH; | |
349 | ||
350 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) | |
351 | return -EFAULT; | |
352 | ||
353 | read_lock(&tasklist_lock); | |
354 | if (likely(child->sighand != NULL)) { | |
355 | error = -EINVAL; | |
356 | spin_lock_irq(&child->sighand->siglock); | |
357 | if (likely(child->last_siginfo != NULL)) { | |
358 | *child->last_siginfo = newinfo; | |
359 | error = 0; | |
360 | } | |
361 | spin_unlock_irq(&child->sighand->siglock); | |
362 | } | |
363 | read_unlock(&tasklist_lock); | |
364 | return error; | |
365 | } | |
366 | ||
367 | int ptrace_request(struct task_struct *child, long request, | |
368 | long addr, long data) | |
369 | { | |
370 | int ret = -EIO; | |
371 | ||
372 | switch (request) { | |
373 | #ifdef PTRACE_OLDSETOPTIONS | |
374 | case PTRACE_OLDSETOPTIONS: | |
375 | #endif | |
376 | case PTRACE_SETOPTIONS: | |
377 | ret = ptrace_setoptions(child, data); | |
378 | break; | |
379 | case PTRACE_GETEVENTMSG: | |
380 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); | |
381 | break; | |
382 | case PTRACE_GETSIGINFO: | |
383 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); | |
384 | break; | |
385 | case PTRACE_SETSIGINFO: | |
386 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); | |
387 | break; | |
388 | default: | |
389 | break; | |
390 | } | |
391 | ||
392 | return ret; | |
393 | } | |
481bed45 | 394 | |
6b9c7ed8 CH |
395 | /** |
396 | * ptrace_traceme -- helper for PTRACE_TRACEME | |
397 | * | |
398 | * Performs checks and sets PT_PTRACED. | |
399 | * Should be used by all ptrace implementations for PTRACE_TRACEME. | |
400 | */ | |
401 | int ptrace_traceme(void) | |
481bed45 | 402 | { |
f5b40e36 | 403 | int ret = -EPERM; |
481bed45 CH |
404 | |
405 | /* | |
6b9c7ed8 CH |
406 | * Are we already being traced? |
407 | */ | |
f5b40e36 LT |
408 | task_lock(current); |
409 | if (!(current->ptrace & PT_PTRACED)) { | |
410 | ret = security_ptrace(current->parent, current); | |
411 | /* | |
412 | * Set the ptrace bit in the process ptrace flags. | |
413 | */ | |
414 | if (!ret) | |
415 | current->ptrace |= PT_PTRACED; | |
416 | } | |
417 | task_unlock(current); | |
418 | return ret; | |
6b9c7ed8 | 419 | } |
481bed45 | 420 | |
6b9c7ed8 CH |
421 | /** |
422 | * ptrace_get_task_struct -- grab a task struct reference for ptrace | |
423 | * @pid: process id to grab a task_struct reference of | |
424 | * | |
425 | * This function is a helper for ptrace implementations. It checks | |
426 | * permissions and then grabs a task struct for use of the actual | |
427 | * ptrace implementation. | |
428 | * | |
429 | * Returns the task_struct for @pid or an ERR_PTR() on failure. | |
430 | */ | |
431 | struct task_struct *ptrace_get_task_struct(pid_t pid) | |
432 | { | |
433 | struct task_struct *child; | |
481bed45 CH |
434 | |
435 | /* | |
6b9c7ed8 | 436 | * Tracing init is not allowed. |
481bed45 CH |
437 | */ |
438 | if (pid == 1) | |
6b9c7ed8 | 439 | return ERR_PTR(-EPERM); |
481bed45 | 440 | |
481bed45 CH |
441 | read_lock(&tasklist_lock); |
442 | child = find_task_by_pid(pid); | |
443 | if (child) | |
444 | get_task_struct(child); | |
f400e198 | 445 | |
481bed45 CH |
446 | read_unlock(&tasklist_lock); |
447 | if (!child) | |
6b9c7ed8 CH |
448 | return ERR_PTR(-ESRCH); |
449 | return child; | |
481bed45 CH |
450 | } |
451 | ||
6b9c7ed8 | 452 | #ifndef __ARCH_SYS_PTRACE |
481bed45 CH |
453 | asmlinkage long sys_ptrace(long request, long pid, long addr, long data) |
454 | { | |
455 | struct task_struct *child; | |
456 | long ret; | |
457 | ||
458 | /* | |
459 | * This lock_kernel fixes a subtle race with suid exec | |
460 | */ | |
461 | lock_kernel(); | |
6b9c7ed8 CH |
462 | if (request == PTRACE_TRACEME) { |
463 | ret = ptrace_traceme(); | |
481bed45 | 464 | goto out; |
6b9c7ed8 CH |
465 | } |
466 | ||
467 | child = ptrace_get_task_struct(pid); | |
468 | if (IS_ERR(child)) { | |
469 | ret = PTR_ERR(child); | |
470 | goto out; | |
471 | } | |
481bed45 CH |
472 | |
473 | if (request == PTRACE_ATTACH) { | |
474 | ret = ptrace_attach(child); | |
005f18df | 475 | goto out_put_task_struct; |
481bed45 CH |
476 | } |
477 | ||
478 | ret = ptrace_check_attach(child, request == PTRACE_KILL); | |
479 | if (ret < 0) | |
480 | goto out_put_task_struct; | |
481 | ||
482 | ret = arch_ptrace(child, request, addr, data); | |
483 | if (ret < 0) | |
484 | goto out_put_task_struct; | |
485 | ||
486 | out_put_task_struct: | |
487 | put_task_struct(child); | |
488 | out: | |
489 | unlock_kernel(); | |
490 | return ret; | |
491 | } | |
492 | #endif /* __ARCH_SYS_PTRACE */ |