[GitHub/mt8127/android_kernel_alcatel_ttab.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/capability.h>
#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)
{
	BUG_ON(!list_empty(&child->ptrace_list));
	if (child->parent == new_parent)
		return;
	list_add(&child->ptrace_list, &child->parent->ptrace_children);
	remove_parent(child);
	child->parent = new_parent;
	add_parent(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)
{
	BUG_ON(!child->ptrace);

	child->ptrace = 0;
	if (!list_empty(&child->ptrace_list)) {
		list_del_init(&child->ptrace_list);
		remove_parent(child);
		child->parent = child->real_parent;
		add_parent(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;
}

static int may_attach(struct task_struct *task)
{
	if (!task->mm)
		return -EPERM;
	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))
		return -EPERM;
	smp_rmb();
	if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
		return -EPERM;

	return security_ptrace(current, task);
}

int ptrace_may_attach(struct task_struct *task)
{
	int err;
	task_lock(task);
	err = may_attach(task);
	task_unlock(task);
	return !err;
}

int ptrace_attach(struct task_struct *task)
{
	int retval;

	retval = -EPERM;
	if (task->pid <= 1)
		goto out;
	if (task->tgid == current->tgid)
		goto out;

repeat:
	/*
	 * Nasty, nasty.
	 *
	 * We want to hold both the task-lock and the
	 * tasklist_lock for writing at the same time.
	 * But that's against the rules (tasklist_lock
	 * is taken for reading by interrupts on other
	 * cpu's that may have task_lock).
	 */
	task_lock(task);
	local_irq_disable();
	if (!write_trylock(&tasklist_lock)) {
		local_irq_enable();
		task_unlock(task);
		do {
			cpu_relax();
		} while (!write_can_lock(&tasklist_lock));
		goto repeat;
	}

	/* the same process cannot be attached many times */
	if (task->ptrace & PT_PTRACED)
		goto bad;
	retval = may_attach(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;

	__ptrace_link(task, current);

	force_sig_specific(SIGSTOP, task);

bad:
	write_unlock_irq(&tasklist_lock);
	task_unlock(task);
out:
	return retval;
}

void __ptrace_detach(struct task_struct *child, unsigned int data)
{
	child->exit_code = data;
	/* .. re-parent .. */
	__ptrace_unlink(child);
	/* .. and wake it up. */
	if (child->exit_state != EXIT_ZOMBIE)
		wake_up_process(child);
}

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

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

	write_lock_irq(&tasklist_lock);
	if (child->ptrace)
		__ptrace_detach(child, data);
	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;
}

/**
 * ptrace_traceme  --  helper for PTRACE_TRACEME
 *
 * Performs checks and sets PT_PTRACED.
 * Should be used by all ptrace implementations for PTRACE_TRACEME.
 */
int ptrace_traceme(void)
{
	int ret = -EPERM;

	/*
	 * Are we already being traced?
	 */
	task_lock(current);
	if (!(current->ptrace & PT_PTRACED)) {
		ret = security_ptrace(current->parent, current);
		/*
		 * Set the ptrace bit in the process ptrace flags.
		 */
		if (!ret)
			current->ptrace |= PT_PTRACED;
	}
	task_unlock(current);
	return ret;
}

/**
 * ptrace_get_task_struct  --  grab a task struct reference for ptrace
 * @pid:       process id to grab a task_struct reference of
 *
 * This function is a helper for ptrace implementations.  It checks
 * permissions and then grabs a task struct for use of the actual
 * ptrace implementation.
 *
 * Returns the task_struct for @pid or an ERR_PTR() on failure.
 */
struct task_struct *ptrace_get_task_struct(pid_t pid)
{
	struct task_struct *child;

	/*
	 * Tracing init is not allowed.
	 */
	if (pid == 1)
		return ERR_PTR(-EPERM);

	read_lock(&tasklist_lock);
	child = find_task_by_pid(pid);
	if (child)
		get_task_struct(child);
	read_unlock(&tasklist_lock);
	if (!child)
		return ERR_PTR(-ESRCH);
	return child;
}

#ifndef __ARCH_SYS_PTRACE
asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
{
	struct task_struct *child;
	long ret;

	/*
	 * This lock_kernel fixes a subtle race with suid exec
	 */
	lock_kernel();
	if (request == PTRACE_TRACEME) {
		ret = ptrace_traceme();
		goto out;
	}

	child = ptrace_get_task_struct(pid);
	if (IS_ERR(child)) {
		ret = PTR_ERR(child);
		goto out;
	}

	if (request == PTRACE_ATTACH) {
		ret = ptrace_attach(child);
		goto out_put_task_struct;
	}

	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	if (ret < 0)
		goto out_put_task_struct;

	ret = arch_ptrace(child, request, addr, data);
	if (ret < 0)
		goto out_put_task_struct;

 out_put_task_struct:
	put_task_struct(child);
 out:
	unlock_kernel();
	return ret;
}
#endif /* __ARCH_SYS_PTRACE */
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	{
524223ca	33	BUG_ON(!list_empty(&child->ptrace_list));
1da177e4 LT	34	if (child->parent == new_parent)
	35	return;
	36	list_add(&child->ptrace_list, &child->parent->ptrace_children);
9b678ece	37	remove_parent(child);
1da177e4	38	child->parent = new_parent;
9b678ece	39	add_parent(child);
1da177e4 LT	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	{
5ecfbae0 ON	70	BUG_ON(!child->ptrace);
5ecfbae0 ON	71
1da177e4 LT	72	child->ptrace = 0;
	73	if (!list_empty(&child->ptrace_list)) {
	74	list_del_init(&child->ptrace_list);
9b678ece	75	remove_parent(child);
1da177e4	76	child->parent = child->real_parent;
9b678ece	77	add_parent(child);
1da177e4 LT	78	}
1da177e4 LT	79
e57a5059 RM	80	if (child->state == TASK_TRACED)
e57a5059 RM	81	ptrace_untrace(child);
1da177e4 LT	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
ab8d11be MS	121	static int may_attach(struct task_struct *task)
	122	{
	123	if (!task->mm)
	124	return -EPERM;
	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))
	131	return -EPERM;
	132	smp_rmb();
	133	if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
	134	return -EPERM;
	135
	136	return security_ptrace(current, task);
	137	}
	138
	139	int ptrace_may_attach(struct task_struct *task)
	140	{
	141	int err;
	142	task_lock(task);
	143	err = may_attach(task);
	144	task_unlock(task);
	145	return !err;
	146	}
	147
1da177e4 LT	148	int ptrace_attach(struct task_struct *task)
	149	{
	150	int retval;
f5b40e36	151
1da177e4 LT	152	retval = -EPERM;
1da177e4 LT	153	if (task->pid <= 1)
f5b40e36	154	goto out;
28d838cc	155	if (task->tgid == current->tgid)
f5b40e36 LT	156	goto out;
f5b40e36 LT	157
f358166a LT	158	repeat:
	159	/*
	160	* Nasty, nasty.
	161	*
	162	* We want to hold both the task-lock and the
	163	* tasklist_lock for writing at the same time.
	164	* But that's against the rules (tasklist_lock
	165	* is taken for reading by interrupts on other
	166	* cpu's that may have task_lock).
	167	*/
f5b40e36	168	task_lock(task);
f358166a LT	169	local_irq_disable();
	170	if (!write_trylock(&tasklist_lock)) {
	171	local_irq_enable();
	172	task_unlock(task);
	173	do {
	174	cpu_relax();
	175	} while (!write_can_lock(&tasklist_lock));
	176	goto repeat;
	177	}
f5b40e36	178
1da177e4 LT	179	/* the same process cannot be attached many times */
	180	if (task->ptrace & PT_PTRACED)
	181	goto bad;
ab8d11be	182	retval = may_attach(task);
1da177e4 LT	183	if (retval)
	184	goto bad;
	185
	186	/* Go */
	187	task->ptrace \|= PT_PTRACED \| ((task->real_parent != current)
	188	? PT_ATTACHED : 0);
	189	if (capable(CAP_SYS_PTRACE))
	190	task->ptrace \|= PT_PTRACE_CAP;
1da177e4	191
1da177e4	192	__ptrace_link(task, current);
1da177e4 LT	193
1da177e4 LT	194	force_sig_specific(SIGSTOP, task);
1da177e4 LT	195
1da177e4 LT	196	bad:
f5b40e36	197	write_unlock_irq(&tasklist_lock);
1da177e4	198	task_unlock(task);
f5b40e36	199	out:
1da177e4 LT	200	return retval;
	201	}
	202
5ecfbae0 ON	203	void __ptrace_detach(struct task_struct *child, unsigned int data)
	204	{
	205	child->exit_code = data;
	206	/* .. re-parent .. */
	207	__ptrace_unlink(child);
	208	/* .. and wake it up. */
	209	if (child->exit_state != EXIT_ZOMBIE)
	210	wake_up_process(child);
	211	}
	212
1da177e4 LT	213	int ptrace_detach(struct task_struct *child, unsigned int data)
1da177e4 LT	214	{
7ed20e1a	215	if (!valid_signal(data))
5ecfbae0	216	return -EIO;
1da177e4 LT	217
	218	/* Architecture-specific hardware disable .. */
	219	ptrace_disable(child);
	220
1da177e4	221	write_lock_irq(&tasklist_lock);
5ecfbae0 ON	222	if (child->ptrace)
5ecfbae0 ON	223	__ptrace_detach(child, data);
1da177e4 LT	224	write_unlock_irq(&tasklist_lock);
	225
	226	return 0;
	227	}
	228
	229	/*
	230	* Access another process' address space.
	231	* Source/target buffer must be kernel space,
	232	* Do not walk the page table directly, use get_user_pages
	233	*/
	234
	235	int access_process_vm(struct task_struct tsk, unsigned long addr, void buf, int len, int write)
	236	{
	237	struct mm_struct *mm;
	238	struct vm_area_struct *vma;
	239	struct page *page;
	240	void *old_buf = buf;
	241
	242	mm = get_task_mm(tsk);
	243	if (!mm)
	244	return 0;
	245
	246	down_read(&mm->mmap_sem);
	247	/* ignore errors, just check how much was sucessfully transfered */
	248	while (len) {
	249	int bytes, ret, offset;
	250	void *maddr;
	251
	252	ret = get_user_pages(tsk, mm, addr, 1,
	253	write, 1, &page, &vma);
	254	if (ret <= 0)
	255	break;
	256
	257	bytes = len;
	258	offset = addr & (PAGE_SIZE-1);
	259	if (bytes > PAGE_SIZE-offset)
	260	bytes = PAGE_SIZE-offset;
	261
	262	maddr = kmap(page);
	263	if (write) {
	264	copy_to_user_page(vma, page, addr,
	265	maddr + offset, buf, bytes);
16bf1348	266	set_page_dirty_lock(page);
1da177e4 LT	267	} else {
	268	copy_from_user_page(vma, page, addr,
	269	buf, maddr + offset, bytes);
	270	}
	271	kunmap(page);
	272	page_cache_release(page);
	273	len -= bytes;
	274	buf += bytes;
	275	addr += bytes;
	276	}
	277	up_read(&mm->mmap_sem);
	278	mmput(mm);
	279
	280	return buf - old_buf;
	281	}
	282
	283	int ptrace_readdata(struct task_struct tsk, unsigned long src, char __user dst, int len)
	284	{
	285	int copied = 0;
	286
	287	while (len > 0) {
	288	char buf[128];
	289	int this_len, retval;
	290
	291	this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
	292	retval = access_process_vm(tsk, src, buf, this_len, 0);
	293	if (!retval) {
	294	if (copied)
	295	break;
	296	return -EIO;
	297	}
	298	if (copy_to_user(dst, buf, retval))
	299	return -EFAULT;
	300	copied += retval;
	301	src += retval;
	302	dst += retval;
	303	len -= retval;
	304	}
	305	return copied;
	306	}
	307
	308	int ptrace_writedata(struct task_struct tsk, char __user src, unsigned long dst, int len)
	309	{
	310	int copied = 0;
	311
	312	while (len > 0) {
	313	char buf[128];
	314	int this_len, retval;
	315
	316	this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
	317	if (copy_from_user(buf, src, this_len))
	318	return -EFAULT;
	319	retval = access_process_vm(tsk, dst, buf, this_len, 1);
	320	if (!retval) {
	321	if (copied)
	322	break;
	323	return -EIO;
	324	}
	325	copied += retval;
	326	src += retval;
	327	dst += retval;
	328	len -= retval;
	329	}
	330	return copied;
331	}
332
333	static int ptrace_setoptions(struct task_struct *child, long data)
334	{
335	child->ptrace &= ~PT_TRACE_MASK;
336
337	if (data & PTRACE_O_TRACESYSGOOD)
338	child->ptrace \|= PT_TRACESYSGOOD;
339
340	if (data & PTRACE_O_TRACEFORK)
341	child->ptrace \|= PT_TRACE_FORK;
342
343	if (data & PTRACE_O_TRACEVFORK)
344	child->ptrace \|= PT_TRACE_VFORK;
345
346	if (data & PTRACE_O_TRACECLONE)
347	child->ptrace \|= PT_TRACE_CLONE;
348
349	if (data & PTRACE_O_TRACEEXEC)
350	child->ptrace \|= PT_TRACE_EXEC;
351
352	if (data & PTRACE_O_TRACEVFORKDONE)
353	child->ptrace \|= PT_TRACE_VFORK_DONE;
354
355	if (data & PTRACE_O_TRACEEXIT)
356	child->ptrace \|= PT_TRACE_EXIT;
357
358	return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
359	}
360
361	static int ptrace_getsiginfo(struct task_struct child, siginfo_t __user data)
362	{
363	siginfo_t lastinfo;
364	int error = -ESRCH;
365
366	read_lock(&tasklist_lock);
367	if (likely(child->sighand != NULL)) {
368	error = -EINVAL;
369	spin_lock_irq(&child->sighand->siglock);
370	if (likely(child->last_siginfo != NULL)) {
371	lastinfo = *child->last_siginfo;
372	error = 0;
373	}
374	spin_unlock_irq(&child->sighand->siglock);
375	}
376	read_unlock(&tasklist_lock);
377	if (!error)
378	return copy_siginfo_to_user(data, &lastinfo);
379	return error;
380	}
381
382	static int ptrace_setsiginfo(struct task_struct child, siginfo_t __user data)
383	{
384	siginfo_t newinfo;
385	int error = -ESRCH;
386
387	if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
388	return -EFAULT;
389
390	read_lock(&tasklist_lock);
391	if (likely(child->sighand != NULL)) {
392	error = -EINVAL;
393	spin_lock_irq(&child->sighand->siglock);
394	if (likely(child->last_siginfo != NULL)) {
395	*child->last_siginfo = newinfo;
396	error = 0;
397	}
398	spin_unlock_irq(&child->sighand->siglock);
399	}
400	read_unlock(&tasklist_lock);
401	return error;
402	}
403
404	int ptrace_request(struct task_struct *child, long request,
405	long addr, long data)
406	{
407	int ret = -EIO;
408
409	switch (request) {
410	#ifdef PTRACE_OLDSETOPTIONS
411	case PTRACE_OLDSETOPTIONS:
412	#endif
413	case PTRACE_SETOPTIONS:
414	ret = ptrace_setoptions(child, data);
415	break;
416	case PTRACE_GETEVENTMSG:
417	ret = put_user(child->ptrace_message, (unsigned long __user *) data);
418	break;
419	case PTRACE_GETSIGINFO:
420	ret = ptrace_getsiginfo(child, (siginfo_t __user *) data);
421	break;
422	case PTRACE_SETSIGINFO:
423	ret = ptrace_setsiginfo(child, (siginfo_t __user *) data);
424	break;
425	default:
426	break;
427	}
428
429	return ret;
430	}
481bed45	431
6b9c7ed8 CH	432	/**
	433	* ptrace_traceme -- helper for PTRACE_TRACEME
	434	*
	435	* Performs checks and sets PT_PTRACED.
	436	* Should be used by all ptrace implementations for PTRACE_TRACEME.
	437	*/
	438	int ptrace_traceme(void)
481bed45	439	{
f5b40e36	440	int ret = -EPERM;
481bed45 CH	441
481bed45 CH	442	/*
6b9c7ed8 CH	443	* Are we already being traced?
6b9c7ed8 CH	444	*/
f5b40e36 LT	445	task_lock(current);
	446	if (!(current->ptrace & PT_PTRACED)) {
	447	ret = security_ptrace(current->parent, current);
	448	/*
	449	* Set the ptrace bit in the process ptrace flags.
	450	*/
	451	if (!ret)
	452	current->ptrace \|= PT_PTRACED;
	453	}
	454	task_unlock(current);
	455	return ret;
6b9c7ed8	456	}
481bed45	457
6b9c7ed8 CH	458	/**
	459	* ptrace_get_task_struct -- grab a task struct reference for ptrace
	460	* @pid: process id to grab a task_struct reference of
	461	*
	462	* This function is a helper for ptrace implementations. It checks
	463	* permissions and then grabs a task struct for use of the actual
	464	* ptrace implementation.
	465	*
	466	* Returns the task_struct for @pid or an ERR_PTR() on failure.
	467	*/
	468	struct task_struct *ptrace_get_task_struct(pid_t pid)
	469	{
	470	struct task_struct *child;
481bed45 CH	471
481bed45 CH	472	/*
6b9c7ed8	473	* Tracing init is not allowed.
481bed45 CH	474	*/
481bed45 CH	475	if (pid == 1)
6b9c7ed8	476	return ERR_PTR(-EPERM);
481bed45	477
481bed45 CH	478	read_lock(&tasklist_lock);
	479	child = find_task_by_pid(pid);
	480	if (child)
	481	get_task_struct(child);
	482	read_unlock(&tasklist_lock);
	483	if (!child)
6b9c7ed8 CH	484	return ERR_PTR(-ESRCH);
6b9c7ed8 CH	485	return child;
481bed45 CH	486	}
481bed45 CH	487
6b9c7ed8	488	#ifndef __ARCH_SYS_PTRACE
481bed45 CH	489	asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
	490	{
	491	struct task_struct *child;
	492	long ret;
	493
	494	/*
	495	* This lock_kernel fixes a subtle race with suid exec
	496	*/
	497	lock_kernel();
6b9c7ed8 CH	498	if (request == PTRACE_TRACEME) {
6b9c7ed8 CH	499	ret = ptrace_traceme();
481bed45	500	goto out;
6b9c7ed8 CH	501	}
	502
	503	child = ptrace_get_task_struct(pid);
	504	if (IS_ERR(child)) {
	505	ret = PTR_ERR(child);
	506	goto out;
	507	}
481bed45 CH	508
	509	if (request == PTRACE_ATTACH) {
	510	ret = ptrace_attach(child);
005f18df	511	goto out_put_task_struct;
481bed45 CH	512	}
	513
	514	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	515	if (ret < 0)
	516	goto out_put_task_struct;
	517
	518	ret = arch_ptrace(child, request, addr, data);
	519	if (ret < 0)
	520	goto out_put_task_struct;
	521
	522	out_put_task_struct:
	523	put_task_struct(child);
	524	out:
	525	unlock_kernel();
	526	return ret;
	527	}
	528	#endif /* __ARCH_SYS_PTRACE */