2 * linux/kernel/ptrace.c
4 * (C) Copyright 1999 Linus Torvalds
6 * Common interfaces for "ptrace()" which we do not want
7 * to continually duplicate across every architecture.
10 #include <linux/capability.h>
11 #include <linux/module.h>
12 #include <linux/sched.h>
13 #include <linux/errno.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>
20 #include <linux/signal.h>
22 #include <asm/pgtable.h>
23 #include <asm/uaccess.h>
26 * ptrace a task: make the debugger its new parent and
27 * move it to the ptrace list.
29 * Must be called with the tasklist lock write-held.
31 void __ptrace_link(task_t
*child
, task_t
*new_parent
)
33 BUG_ON(!list_empty(&child
->ptrace_list
));
34 if (child
->parent
== new_parent
)
36 list_add(&child
->ptrace_list
, &child
->parent
->ptrace_children
);
38 child
->parent
= new_parent
;
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.
49 void ptrace_untrace(task_t
*child
)
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
;
56 signal_wake_up(child
, 1);
59 spin_unlock(&child
->sighand
->siglock
);
63 * unptrace a task: move it back to its original parent and
64 * remove it from the ptrace list.
66 * Must be called with the tasklist lock write-held.
68 void __ptrace_unlink(task_t
*child
)
70 BUG_ON(!child
->ptrace
);
73 if (!list_empty(&child
->ptrace_list
)) {
74 list_del_init(&child
->ptrace_list
);
76 child
->parent
= child
->real_parent
;
80 if (child
->state
== TASK_TRACED
)
81 ptrace_untrace(child
);
85 * Check that we have indeed attached to the thing..
87 int ptrace_check_attach(struct task_struct
*child
, int kill
)
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.
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
) {
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
) {
109 spin_unlock_irq(&child
->sighand
->siglock
);
111 read_unlock(&tasklist_lock
);
114 wait_task_inactive(child
);
117 /* All systems go.. */
121 static int may_attach(struct task_struct
*task
)
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
))
133 if (!task
->mm
->dumpable
&& !capable(CAP_SYS_PTRACE
))
136 return security_ptrace(current
, task
);
139 int ptrace_may_attach(struct task_struct
*task
)
143 err
= may_attach(task
);
148 int ptrace_attach(struct task_struct
*task
)
155 if (task
->tgid
== current
->tgid
)
158 write_lock_irq(&tasklist_lock
);
161 /* the same process cannot be attached many times */
162 if (task
->ptrace
& PT_PTRACED
)
164 retval
= may_attach(task
);
169 task
->ptrace
|= PT_PTRACED
| ((task
->real_parent
!= current
)
171 if (capable(CAP_SYS_PTRACE
))
172 task
->ptrace
|= PT_PTRACE_CAP
;
174 __ptrace_link(task
, current
);
176 force_sig_specific(SIGSTOP
, task
);
179 write_unlock_irq(&tasklist_lock
);
185 void __ptrace_detach(struct task_struct
*child
, unsigned int data
)
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
);
195 int ptrace_detach(struct task_struct
*child
, unsigned int data
)
197 if (!valid_signal(data
))
200 /* Architecture-specific hardware disable .. */
201 ptrace_disable(child
);
203 write_lock_irq(&tasklist_lock
);
205 __ptrace_detach(child
, data
);
206 write_unlock_irq(&tasklist_lock
);
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
217 int access_process_vm(struct task_struct
*tsk
, unsigned long addr
, void *buf
, int len
, int write
)
219 struct mm_struct
*mm
;
220 struct vm_area_struct
*vma
;
224 mm
= get_task_mm(tsk
);
228 down_read(&mm
->mmap_sem
);
229 /* ignore errors, just check how much was sucessfully transfered */
231 int bytes
, ret
, offset
;
234 ret
= get_user_pages(tsk
, mm
, addr
, 1,
235 write
, 1, &page
, &vma
);
240 offset
= addr
& (PAGE_SIZE
-1);
241 if (bytes
> PAGE_SIZE
-offset
)
242 bytes
= PAGE_SIZE
-offset
;
246 copy_to_user_page(vma
, page
, addr
,
247 maddr
+ offset
, buf
, bytes
);
248 set_page_dirty_lock(page
);
250 copy_from_user_page(vma
, page
, addr
,
251 buf
, maddr
+ offset
, bytes
);
254 page_cache_release(page
);
259 up_read(&mm
->mmap_sem
);
262 return buf
- old_buf
;
265 int ptrace_readdata(struct task_struct
*tsk
, unsigned long src
, char __user
*dst
, int len
)
271 int this_len
, retval
;
273 this_len
= (len
> sizeof(buf
)) ? sizeof(buf
) : len
;
274 retval
= access_process_vm(tsk
, src
, buf
, this_len
, 0);
280 if (copy_to_user(dst
, buf
, retval
))
290 int ptrace_writedata(struct task_struct
*tsk
, char __user
*src
, unsigned long dst
, int len
)
296 int this_len
, retval
;
298 this_len
= (len
> sizeof(buf
)) ? sizeof(buf
) : len
;
299 if (copy_from_user(buf
, src
, this_len
))
301 retval
= access_process_vm(tsk
, dst
, buf
, this_len
, 1);
315 static int ptrace_setoptions(struct task_struct
*child
, long data
)
317 child
->ptrace
&= ~PT_TRACE_MASK
;
319 if (data
& PTRACE_O_TRACESYSGOOD
)
320 child
->ptrace
|= PT_TRACESYSGOOD
;
322 if (data
& PTRACE_O_TRACEFORK
)
323 child
->ptrace
|= PT_TRACE_FORK
;
325 if (data
& PTRACE_O_TRACEVFORK
)
326 child
->ptrace
|= PT_TRACE_VFORK
;
328 if (data
& PTRACE_O_TRACECLONE
)
329 child
->ptrace
|= PT_TRACE_CLONE
;
331 if (data
& PTRACE_O_TRACEEXEC
)
332 child
->ptrace
|= PT_TRACE_EXEC
;
334 if (data
& PTRACE_O_TRACEVFORKDONE
)
335 child
->ptrace
|= PT_TRACE_VFORK_DONE
;
337 if (data
& PTRACE_O_TRACEEXIT
)
338 child
->ptrace
|= PT_TRACE_EXIT
;
340 return (data
& ~PTRACE_O_MASK
) ? -EINVAL
: 0;
343 static int ptrace_getsiginfo(struct task_struct
*child
, siginfo_t __user
* data
)
348 read_lock(&tasklist_lock
);
349 if (likely(child
->sighand
!= NULL
)) {
351 spin_lock_irq(&child
->sighand
->siglock
);
352 if (likely(child
->last_siginfo
!= NULL
)) {
353 lastinfo
= *child
->last_siginfo
;
356 spin_unlock_irq(&child
->sighand
->siglock
);
358 read_unlock(&tasklist_lock
);
360 return copy_siginfo_to_user(data
, &lastinfo
);
364 static int ptrace_setsiginfo(struct task_struct
*child
, siginfo_t __user
* data
)
369 if (copy_from_user(&newinfo
, data
, sizeof (siginfo_t
)))
372 read_lock(&tasklist_lock
);
373 if (likely(child
->sighand
!= NULL
)) {
375 spin_lock_irq(&child
->sighand
->siglock
);
376 if (likely(child
->last_siginfo
!= NULL
)) {
377 *child
->last_siginfo
= newinfo
;
380 spin_unlock_irq(&child
->sighand
->siglock
);
382 read_unlock(&tasklist_lock
);
386 int ptrace_request(struct task_struct
*child
, long request
,
387 long addr
, long data
)
392 #ifdef PTRACE_OLDSETOPTIONS
393 case PTRACE_OLDSETOPTIONS
:
395 case PTRACE_SETOPTIONS
:
396 ret
= ptrace_setoptions(child
, data
);
398 case PTRACE_GETEVENTMSG
:
399 ret
= put_user(child
->ptrace_message
, (unsigned long __user
*) data
);
401 case PTRACE_GETSIGINFO
:
402 ret
= ptrace_getsiginfo(child
, (siginfo_t __user
*) data
);
404 case PTRACE_SETSIGINFO
:
405 ret
= ptrace_setsiginfo(child
, (siginfo_t __user
*) data
);
415 * ptrace_traceme -- helper for PTRACE_TRACEME
417 * Performs checks and sets PT_PTRACED.
418 * Should be used by all ptrace implementations for PTRACE_TRACEME.
420 int ptrace_traceme(void)
425 * Are we already being traced?
428 if (!(current
->ptrace
& PT_PTRACED
)) {
429 ret
= security_ptrace(current
->parent
, current
);
431 * Set the ptrace bit in the process ptrace flags.
434 current
->ptrace
|= PT_PTRACED
;
436 task_unlock(current
);
441 * ptrace_get_task_struct -- grab a task struct reference for ptrace
442 * @pid: process id to grab a task_struct reference of
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.
448 * Returns the task_struct for @pid or an ERR_PTR() on failure.
450 struct task_struct
*ptrace_get_task_struct(pid_t pid
)
452 struct task_struct
*child
;
455 * Tracing init is not allowed.
458 return ERR_PTR(-EPERM
);
460 read_lock(&tasklist_lock
);
461 child
= find_task_by_pid(pid
);
463 get_task_struct(child
);
464 read_unlock(&tasklist_lock
);
466 return ERR_PTR(-ESRCH
);
470 #ifndef __ARCH_SYS_PTRACE
471 asmlinkage
long sys_ptrace(long request
, long pid
, long addr
, long data
)
473 struct task_struct
*child
;
477 * This lock_kernel fixes a subtle race with suid exec
480 if (request
== PTRACE_TRACEME
) {
481 ret
= ptrace_traceme();
485 child
= ptrace_get_task_struct(pid
);
487 ret
= PTR_ERR(child
);
491 if (request
== PTRACE_ATTACH
) {
492 ret
= ptrace_attach(child
);
493 goto out_put_task_struct
;
496 ret
= ptrace_check_attach(child
, request
== PTRACE_KILL
);
498 goto out_put_task_struct
;
500 ret
= arch_ptrace(child
, request
, addr
, data
);
502 goto out_put_task_struct
;
505 put_task_struct(child
);
510 #endif /* __ARCH_SYS_PTRACE */
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