[linux.git] / kernel / ptrace.c

/*
 * linux/kernel/ptrace.c
 *
 * (C) Copyright 1999 Linus Torvalds
 *
 * Common interfaces for "ptrace()" which we do not want
 * to continually duplicate across every architecture.
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>
#include <linux/ptrace.h>
#include <linux/security.h>
#include <linux/signal.h>

#include <asm/pgtable.h>
#include <asm/uaccess.h>

/*
 * ptrace a task: make the debugger its new parent and
 * move it to the ptrace list.
 *
 * Must be called with the tasklist lock write-held.
 */
void __ptrace_link(task_t *child, task_t *new_parent)
{
	if (!list_empty(&child->ptrace_list))
		BUG();
	if (child->parent == new_parent)
		return;
	list_add(&child->ptrace_list, &child->parent->ptrace_children);
	REMOVE_LINKS(child);
	child->parent = new_parent;
	SET_LINKS(child);
}
 
/*
 * Turn a tracing stop into a normal stop now, since with no tracer there
 * would be no way to wake it up with SIGCONT or SIGKILL.  If there was a
 * signal sent that would resume the child, but didn't because it was in
 * TASK_TRACED, resume it now.
 * Requires that irqs be disabled.
 */
void ptrace_untrace(task_t *child)
{
	spin_lock(&child->sighand->siglock);
	if (child->state == TASK_TRACED) {
		if (child->signal->flags & SIGNAL_STOP_STOPPED) {
			child->state = TASK_STOPPED;
		} else {
			signal_wake_up(child, 1);
		}
	}
	spin_unlock(&child->sighand->siglock);
}

/*
 * unptrace a task: move it back to its original parent and
 * remove it from the ptrace list.
 *
 * Must be called with the tasklist lock write-held.
 */
void __ptrace_unlink(task_t *child)
{
	if (!child->ptrace)
		BUG();
	child->ptrace = 0;
	if (!list_empty(&child->ptrace_list)) {
		list_del_init(&child->ptrace_list);
		REMOVE_LINKS(child);
		child->parent = child->real_parent;
		SET_LINKS(child);
	}

	if (child->state == TASK_TRACED)
		ptrace_untrace(child);
}

/*
 * Check that we have indeed attached to the thing..
 */
int ptrace_check_attach(struct task_struct *child, int kill)
{
	int ret = -ESRCH;

	/*
	 * We take the read lock around doing both checks to close a
	 * possible race where someone else was tracing our child and
	 * detached between these two checks.  After this locked check,
	 * we are sure that this is our traced child and that can only
	 * be changed by us so it's not changing right after this.
	 */
	read_lock(&tasklist_lock);
	if ((child->ptrace & PT_PTRACED) && child->parent == current &&
	    (!(child->ptrace & PT_ATTACHED) || child->real_parent != current)
	    && child->signal != NULL) {
		ret = 0;
		spin_lock_irq(&child->sighand->siglock);
		if (child->state == TASK_STOPPED) {
			child->state = TASK_TRACED;
		} else if (child->state != TASK_TRACED && !kill) {
			ret = -ESRCH;
		}
		spin_unlock_irq(&child->sighand->siglock);
	}
	read_unlock(&tasklist_lock);

	if (!ret && !kill) {
		wait_task_inactive(child);
	}

	/* All systems go.. */
	return ret;
}

int ptrace_attach(struct task_struct *task)
{
	int retval;
	task_lock(task);
	retval = -EPERM;
	if (task->pid <= 1)
		goto bad;
	if (task == current)
		goto bad;
	if (!task->mm)
		goto bad;
	if(((current->uid != task->euid) ||
	    (current->uid != task->suid) ||
	    (current->uid != task->uid) ||
 	    (current->gid != task->egid) ||
 	    (current->gid != task->sgid) ||
 	    (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
		goto bad;
	smp_rmb();
	if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
		goto bad;
	/* the same process cannot be attached many times */
	if (task->ptrace & PT_PTRACED)
		goto bad;
	retval = security_ptrace(current, task);
	if (retval)
		goto bad;

	/* Go */
	task->ptrace |= PT_PTRACED | ((task->real_parent != current)
				      ? PT_ATTACHED : 0);
	if (capable(CAP_SYS_PTRACE))
		task->ptrace |= PT_PTRACE_CAP;
	task_unlock(task);

	write_lock_irq(&tasklist_lock);
	__ptrace_link(task, current);
	write_unlock_irq(&tasklist_lock);

	force_sig_specific(SIGSTOP, task);
	return 0;

bad:
	task_unlock(task);
	return retval;
}

int ptrace_detach(struct task_struct *child, unsigned int data)
{
	if (!valid_signal(data))
		return	-EIO;

	/* Architecture-specific hardware disable .. */
	ptrace_disable(child);

	/* .. re-parent .. */
	child->exit_code = data;

	write_lock_irq(&tasklist_lock);
	__ptrace_unlink(child);
	/* .. and wake it up. */
	if (child->exit_state != EXIT_ZOMBIE)
		wake_up_process(child);
	write_unlock_irq(&tasklist_lock);

	return 0;
}

/*
 * Access another process' address space.
 * Source/target buffer must be kernel space, 
 * Do not walk the page table directly, use get_user_pages
 */

int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	struct page *page;
	void *old_buf = buf;

	mm = get_task_mm(tsk);
	if (!mm)
		return 0;

	down_read(&mm->mmap_sem);
	/* ignore errors, just check how much was sucessfully transfered */
	while (len) {
		int bytes, ret, offset;
		void *maddr;

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
		if (ret <= 0)
			break;

		bytes = len;
		offset = addr & (PAGE_SIZE-1);
		if (bytes > PAGE_SIZE-offset)
			bytes = PAGE_SIZE-offset;

		maddr = kmap(page);
		if (write) {
			copy_to_user_page(vma, page, addr,
					  maddr + offset, buf, bytes);
			set_page_dirty_lock(page);
		} else {
			copy_from_user_page(vma, page, addr,
					    buf, maddr + offset, bytes);
		}
		kunmap(page);
		page_cache_release(page);
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);
	
	return buf - old_buf;
}

int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
{
	int copied = 0;

	while (len > 0) {
		char buf[128];
		int this_len, retval;

		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
		retval = access_process_vm(tsk, src, buf, this_len, 0);
		if (!retval) {
			if (copied)
				break;
			return -EIO;
		}
		if (copy_to_user(dst, buf, retval))
			return -EFAULT;
		copied += retval;
		src += retval;
		dst += retval;
		len -= retval;			
	}
	return copied;
}

int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
{
	int copied = 0;

	while (len > 0) {
		char buf[128];
		int this_len, retval;

		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
		if (copy_from_user(buf, src, this_len))
			return -EFAULT;
		retval = access_process_vm(tsk, dst, buf, this_len, 1);
		if (!retval) {
			if (copied)
				break;
			return -EIO;
		}
		copied += retval;
		src += retval;
		dst += retval;
		len -= retval;			
	}
	return copied;
}

static int ptrace_setoptions(struct task_struct *child, long data)
{
	child->ptrace &= ~PT_TRACE_MASK;

	if (data & PTRACE_O_TRACESYSGOOD)
		child->ptrace |= PT_TRACESYSGOOD;

	if (data & PTRACE_O_TRACEFORK)
		child->ptrace |= PT_TRACE_FORK;

	if (data & PTRACE_O_TRACEVFORK)
		child->ptrace |= PT_TRACE_VFORK;

	if (data & PTRACE_O_TRACECLONE)
		child->ptrace |= PT_TRACE_CLONE;

	if (data & PTRACE_O_TRACEEXEC)
		child->ptrace |= PT_TRACE_EXEC;

	if (data & PTRACE_O_TRACEVFORKDONE)
		child->ptrace |= PT_TRACE_VFORK_DONE;

	if (data & PTRACE_O_TRACEEXIT)
		child->ptrace |= PT_TRACE_EXIT;

	return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
}

static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
{
	siginfo_t lastinfo;
	int error = -ESRCH;

	read_lock(&tasklist_lock);
	if (likely(child->sighand != NULL)) {
		error = -EINVAL;
		spin_lock_irq(&child->sighand->siglock);
		if (likely(child->last_siginfo != NULL)) {
			lastinfo = *child->last_siginfo;
			error = 0;
		}
		spin_unlock_irq(&child->sighand->siglock);
	}
	read_unlock(&tasklist_lock);
	if (!error)
		return copy_siginfo_to_user(data, &lastinfo);
	return error;
}

static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data)
{
	siginfo_t newinfo;
	int error = -ESRCH;

	if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
		return -EFAULT;

	read_lock(&tasklist_lock);
	if (likely(child->sighand != NULL)) {
		error = -EINVAL;
		spin_lock_irq(&child->sighand->siglock);
		if (likely(child->last_siginfo != NULL)) {
			*child->last_siginfo = newinfo;
			error = 0;
		}
		spin_unlock_irq(&child->sighand->siglock);
	}
	read_unlock(&tasklist_lock);
	return error;
}

int ptrace_request(struct task_struct *child, long request,
		   long addr, long data)
{
	int ret = -EIO;

	switch (request) {
#ifdef PTRACE_OLDSETOPTIONS
	case PTRACE_OLDSETOPTIONS:
#endif
	case PTRACE_SETOPTIONS:
		ret = ptrace_setoptions(child, data);
		break;
	case PTRACE_GETEVENTMSG:
		ret = put_user(child->ptrace_message, (unsigned long __user *) data);
		break;
	case PTRACE_GETSIGINFO:
		ret = ptrace_getsiginfo(child, (siginfo_t __user *) data);
		break;
	case PTRACE_SETSIGINFO:
		ret = ptrace_setsiginfo(child, (siginfo_t __user *) data);
		break;
	default:
		break;
	}

	return ret;
}
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
	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	}
	59	spin_unlock(&child->sighand->siglock);
	60	}
	61
	62	/*
	63	* unptrace a task: move it back to its original parent and
	64	* remove it from the ptrace list.
	65	*
	66	* Must be called with the tasklist lock write-held.
	67	*/
	68	void __ptrace_unlink(task_t *child)
	69	{
	70	if (!child->ptrace)
	71	BUG();
	72	child->ptrace = 0;
	73	if (!list_empty(&child->ptrace_list)) {
	74	list_del_init(&child->ptrace_list);
	75	REMOVE_LINKS(child);
	76	child->parent = child->real_parent;
	77	SET_LINKS(child);
	78	}
	79
	80	if (child->state == TASK_TRACED)
	81	ptrace_untrace(child);
	82	}
	83
84	/*
85	* Check that we have indeed attached to the thing..
86	*/
87	int ptrace_check_attach(struct task_struct *child, int kill)
88	{
89	int ret = -ESRCH;
90
91	/*
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.
97	*/
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) {
102	ret = 0;
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) {
107	ret = -ESRCH;
108	}
109	spin_unlock_irq(&child->sighand->siglock);
110	}
111	read_unlock(&tasklist_lock);
112
113	if (!ret && !kill) {
114	wait_task_inactive(child);
115	}
116
117	/* All systems go.. */
118	return ret;
119	}
120
121	int ptrace_attach(struct task_struct *task)
122	{
123	int retval;
124	task_lock(task);
125	retval = -EPERM;
126	if (task->pid <= 1)
127	goto bad;
128	if (task == current)
129	goto bad;
130	if (!task->mm)
131	goto bad;
132	if(((current->uid != task->euid) \|\|
133	(current->uid != task->suid) \|\|
134	(current->uid != task->uid) \|\|
135	(current->gid != task->egid) \|\|
136	(current->gid != task->sgid) \|\|
137	(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
138	goto bad;
d59dd462	139	smp_rmb();
1da177e4 LT	140	if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
	141	goto bad;
	142	/* the same process cannot be attached many times */
	143	if (task->ptrace & PT_PTRACED)
	144	goto bad;
	145	retval = security_ptrace(current, task);
	146	if (retval)
	147	goto bad;
	148
	149	/* Go */
	150	task->ptrace \|= PT_PTRACED \| ((task->real_parent != current)
	151	? PT_ATTACHED : 0);
	152	if (capable(CAP_SYS_PTRACE))
	153	task->ptrace \|= PT_PTRACE_CAP;
	154	task_unlock(task);
	155
	156	write_lock_irq(&tasklist_lock);
	157	__ptrace_link(task, current);
	158	write_unlock_irq(&tasklist_lock);
	159
	160	force_sig_specific(SIGSTOP, task);
	161	return 0;
	162
	163	bad:
	164	task_unlock(task);
	165	return retval;
	166	}
	167
	168	int ptrace_detach(struct task_struct *child, unsigned int data)
	169	{
7ed20e1a	170	if (!valid_signal(data))
1da177e4 LT	171	return -EIO;
	172
	173	/* Architecture-specific hardware disable .. */
	174	ptrace_disable(child);
	175
	176	/* .. re-parent .. */
	177	child->exit_code = data;
	178
	179	write_lock_irq(&tasklist_lock);
	180	__ptrace_unlink(child);
	181	/* .. and wake it up. */
	182	if (child->exit_state != EXIT_ZOMBIE)
	183	wake_up_process(child);
	184	write_unlock_irq(&tasklist_lock);
	185
	186	return 0;
	187	}
	188
	189	/*
	190	* Access another process' address space.
	191	* Source/target buffer must be kernel space,
	192	* Do not walk the page table directly, use get_user_pages
	193	*/
	194
	195	int access_process_vm(struct task_struct tsk, unsigned long addr, void buf, int len, int write)
	196	{
	197	struct mm_struct *mm;
	198	struct vm_area_struct *vma;
	199	struct page *page;
	200	void *old_buf = buf;
	201
	202	mm = get_task_mm(tsk);
	203	if (!mm)
	204	return 0;
	205
	206	down_read(&mm->mmap_sem);
	207	/* ignore errors, just check how much was sucessfully transfered */
	208	while (len) {
	209	int bytes, ret, offset;
	210	void *maddr;
	211
	212	ret = get_user_pages(tsk, mm, addr, 1,
	213	write, 1, &page, &vma);
	214	if (ret <= 0)
	215	break;
	216
	217	bytes = len;
	218	offset = addr & (PAGE_SIZE-1);
	219	if (bytes > PAGE_SIZE-offset)
	220	bytes = PAGE_SIZE-offset;
	221
	222	maddr = kmap(page);
	223	if (write) {
	224	copy_to_user_page(vma, page, addr,
	225	maddr + offset, buf, bytes);
	226	set_page_dirty_lock(page);
	227	} else {
	228	copy_from_user_page(vma, page, addr,
	229	buf, maddr + offset, bytes);
	230	}
	231	kunmap(page);
	232	page_cache_release(page);
	233	len -= bytes;
	234	buf += bytes;
235	addr += bytes;
236	}
237	up_read(&mm->mmap_sem);
238	mmput(mm);
239
240	return buf - old_buf;
241	}
242
243	int ptrace_readdata(struct task_struct tsk, unsigned long src, char __user dst, int len)
244	{
245	int copied = 0;
246
247	while (len > 0) {
248	char buf[128];
249	int this_len, retval;
250
251	this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
252	retval = access_process_vm(tsk, src, buf, this_len, 0);
253	if (!retval) {
254	if (copied)
255	break;
256	return -EIO;
257	}
258	if (copy_to_user(dst, buf, retval))
259	return -EFAULT;
260	copied += retval;
261	src += retval;
262	dst += retval;
263	len -= retval;
264	}
265	return copied;
266	}
267
268	int ptrace_writedata(struct task_struct tsk, char __user src, unsigned long dst, int len)
269	{
270	int copied = 0;
271
272	while (len > 0) {
273	char buf[128];
274	int this_len, retval;
275
276	this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
277	if (copy_from_user(buf, src, this_len))
278	return -EFAULT;
279	retval = access_process_vm(tsk, dst, buf, this_len, 1);
280	if (!retval) {
281	if (copied)
282	break;
283	return -EIO;
284	}
285	copied += retval;
286	src += retval;
287	dst += retval;
288	len -= retval;
289	}
290	return copied;
291	}
292
293	static int ptrace_setoptions(struct task_struct *child, long data)
294	{
295	child->ptrace &= ~PT_TRACE_MASK;
296
297	if (data & PTRACE_O_TRACESYSGOOD)
298	child->ptrace \|= PT_TRACESYSGOOD;
299
300	if (data & PTRACE_O_TRACEFORK)
301	child->ptrace \|= PT_TRACE_FORK;
302
303	if (data & PTRACE_O_TRACEVFORK)
304	child->ptrace \|= PT_TRACE_VFORK;
305
306	if (data & PTRACE_O_TRACECLONE)
307	child->ptrace \|= PT_TRACE_CLONE;
308
309	if (data & PTRACE_O_TRACEEXEC)
310	child->ptrace \|= PT_TRACE_EXEC;
311
312	if (data & PTRACE_O_TRACEVFORKDONE)
313	child->ptrace \|= PT_TRACE_VFORK_DONE;
314
315	if (data & PTRACE_O_TRACEEXIT)
316	child->ptrace \|= PT_TRACE_EXIT;
317
318	return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
319	}
320
321	static int ptrace_getsiginfo(struct task_struct child, siginfo_t __user data)
322	{
323	siginfo_t lastinfo;
324	int error = -ESRCH;
325
326	read_lock(&tasklist_lock);
327	if (likely(child->sighand != NULL)) {
328	error = -EINVAL;
329	spin_lock_irq(&child->sighand->siglock);
330	if (likely(child->last_siginfo != NULL)) {
331	lastinfo = *child->last_siginfo;
332	error = 0;
333	}
334	spin_unlock_irq(&child->sighand->siglock);
335	}
336	read_unlock(&tasklist_lock);
337	if (!error)
338	return copy_siginfo_to_user(data, &lastinfo);
339	return error;
340	}
341
342	static int ptrace_setsiginfo(struct task_struct child, siginfo_t __user data)
343	{
344	siginfo_t newinfo;
345	int error = -ESRCH;
346
347	if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
348	return -EFAULT;
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	*child->last_siginfo = newinfo;
356	error = 0;
357	}
358	spin_unlock_irq(&child->sighand->siglock);
359	}
360	read_unlock(&tasklist_lock);
361	return error;
362	}
363
364	int ptrace_request(struct task_struct *child, long request,
365	long addr, long data)
366	{
367	int ret = -EIO;
368
369	switch (request) {
370	#ifdef PTRACE_OLDSETOPTIONS
371	case PTRACE_OLDSETOPTIONS:
372	#endif
373	case PTRACE_SETOPTIONS:
374	ret = ptrace_setoptions(child, data);
375	break;
376	case PTRACE_GETEVENTMSG:
377	ret = put_user(child->ptrace_message, (unsigned long __user *) data);
378	break;
379	case PTRACE_GETSIGINFO:
380	ret = ptrace_getsiginfo(child, (siginfo_t __user *) data);
381	break;
382	case PTRACE_SETSIGINFO:
383	ret = ptrace_setsiginfo(child, (siginfo_t __user *) data);
384	break;
385	default:
386	break;
387	}
388
389	return ret;
390	}