[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/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 <linux/audit.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(struct task_struct *child, struct task_struct *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(struct task_struct *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(struct task_struct *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)
{
	/* May we inspect the given task?
	 * This check is used both for attaching with ptrace
	 * and for allowing access to sensitive information in /proc.
	 *
	 * ptrace_attach denies several cases that /proc allows
	 * because setting up the necessary parent/child relationship
	 * or halting the specified task is impossible.
	 */
	int dumpable = 0;
	/* Don't let security modules deny introspection */
	if (task == current)
		return 0;
	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 = get_dumpable(task->mm);
	if (!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;
	unsigned long flags;

	audit_ptrace(task);

	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);
	if (!write_trylock_irqsave(&tasklist_lock, flags)) {
		task_unlock(task);
		do {
			cpu_relax();
		} while (!write_can_lock(&tasklist_lock));
		goto repeat;
	}

	if (!task->mm)
		goto bad;
	/* 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_irqrestore(&tasklist_lock, flags);
	task_unlock(task);
out:
	return retval;
}

static inline 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);
	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

	write_lock_irq(&tasklist_lock);
	/* protect against de_thread()->release_task() */
	if (child->ptrace)
		__ptrace_detach(child, data);
	write_unlock_irq(&tasklist_lock);

	return 0;
}

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 */

int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data)
{
	unsigned long tmp;
	int copied;

	copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
	if (copied != sizeof(tmp))
		return -EIO;
	return put_user(tmp, (unsigned long __user *)data);
}

int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
{
	int copied;

	copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
	return (copied == sizeof(data)) ? 0 : -EIO;
}
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);
5ecfbae0 ON	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	}
1da177e4 LT	80
e57a5059 RM	81	if (child->state == TASK_TRACED)
e57a5059 RM	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)
ab8d11be MS	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	144	if (task->mm)
6c5d5238	145	dumpable = get_dumpable(task->mm);
df26c40e	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);
a5cb013d AV	167
1da177e4 LT	168	retval = -EPERM;
1da177e4 LT	169	if (task->pid <= 1)
f5b40e36	170	goto out;
28d838cc	171	if (task->tgid == current->tgid)
f5b40e36 LT	172	goto out;
f5b40e36 LT	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)
df26c40e EB	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
1da177e4 LT	210	force_sig_specific(SIGSTOP, task);
1da177e4 LT	211
1da177e4 LT	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)
1da177e4 LT	230	{
7ed20e1a	231	if (!valid_signal(data))
5ecfbae0	232	return -EIO;
1da177e4 LT	233
	234	/* Architecture-specific hardware disable .. */
	235	ptrace_disable(child);
7d941432	236	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
1da177e4	237
1da177e4	238	write_lock_irq(&tasklist_lock);
d5f70c00	239	/* protect against de_thread()->release_task() */
5ecfbae0 ON	240	if (child->ptrace)
5ecfbae0 ON	241	__ptrace_detach(child, data);
1da177e4 LT	242	write_unlock_irq(&tasklist_lock);
	243
	244	return 0;
	245	}
	246
1da177e4 LT	247	int ptrace_readdata(struct task_struct tsk, unsigned long src, char __user dst, int len)
	248	{
	249	int copied = 0;
	250
	251	while (len > 0) {
	252	char buf[128];
	253	int this_len, retval;
	254
	255	this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
	256	retval = access_process_vm(tsk, src, buf, this_len, 0);
	257	if (!retval) {
	258	if (copied)
	259	break;
	260	return -EIO;
	261	}
	262	if (copy_to_user(dst, buf, retval))
	263	return -EFAULT;
	264	copied += retval;
	265	src += retval;
	266	dst += retval;
	267	len -= retval;
	268	}
	269	return copied;
	270	}
	271
	272	int ptrace_writedata(struct task_struct tsk, char __user src, unsigned long dst, int len)
	273	{
	274	int copied = 0;
	275
	276	while (len > 0) {
	277	char buf[128];
	278	int this_len, retval;
	279
	280	this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
	281	if (copy_from_user(buf, src, this_len))
	282	return -EFAULT;
	283	retval = access_process_vm(tsk, dst, buf, this_len, 1);
	284	if (!retval) {
	285	if (copied)
	286	break;
	287	return -EIO;
	288	}
	289	copied += retval;
	290	src += retval;
	291	dst += retval;
	292	len -= retval;
	293	}
	294	return copied;
	295	}
	296
	297	static int ptrace_setoptions(struct task_struct *child, long data)
	298	{
	299	child->ptrace &= ~PT_TRACE_MASK;
	300
	301	if (data & PTRACE_O_TRACESYSGOOD)
	302	child->ptrace \|= PT_TRACESYSGOOD;
	303
	304	if (data & PTRACE_O_TRACEFORK)
	305	child->ptrace \|= PT_TRACE_FORK;
	306
	307	if (data & PTRACE_O_TRACEVFORK)
	308	child->ptrace \|= PT_TRACE_VFORK;
	309
	310	if (data & PTRACE_O_TRACECLONE)
311	child->ptrace \|= PT_TRACE_CLONE;
312
313	if (data & PTRACE_O_TRACEEXEC)
314	child->ptrace \|= PT_TRACE_EXEC;
315
316	if (data & PTRACE_O_TRACEVFORKDONE)
317	child->ptrace \|= PT_TRACE_VFORK_DONE;
318
319	if (data & PTRACE_O_TRACEEXIT)
320	child->ptrace \|= PT_TRACE_EXIT;
321
322	return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
323	}
324
325	static int ptrace_getsiginfo(struct task_struct child, siginfo_t __user data)
326	{
327	siginfo_t lastinfo;
328	int error = -ESRCH;
329
330	read_lock(&tasklist_lock);
331	if (likely(child->sighand != NULL)) {
332	error = -EINVAL;
333	spin_lock_irq(&child->sighand->siglock);
334	if (likely(child->last_siginfo != NULL)) {
335	lastinfo = *child->last_siginfo;
336	error = 0;
337	}
338	spin_unlock_irq(&child->sighand->siglock);
339	}
340	read_unlock(&tasklist_lock);
341	if (!error)
342	return copy_siginfo_to_user(data, &lastinfo);
343	return error;
344	}
345
346	static int ptrace_setsiginfo(struct task_struct child, siginfo_t __user data)
347	{
348	siginfo_t newinfo;
349	int error = -ESRCH;
350
351	if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
352	return -EFAULT;
353
354	read_lock(&tasklist_lock);
355	if (likely(child->sighand != NULL)) {
356	error = -EINVAL;
357	spin_lock_irq(&child->sighand->siglock);
358	if (likely(child->last_siginfo != NULL)) {
359	*child->last_siginfo = newinfo;
360	error = 0;
361	}
362	spin_unlock_irq(&child->sighand->siglock);
363	}
364	read_unlock(&tasklist_lock);
365	return error;
366	}
367
368	int ptrace_request(struct task_struct *child, long request,
369	long addr, long data)
370	{
371	int ret = -EIO;
372
373	switch (request) {
374	#ifdef PTRACE_OLDSETOPTIONS
375	case PTRACE_OLDSETOPTIONS:
376	#endif
377	case PTRACE_SETOPTIONS:
378	ret = ptrace_setoptions(child, data);
379	break;
380	case PTRACE_GETEVENTMSG:
381	ret = put_user(child->ptrace_message, (unsigned long __user *) data);
382	break;
383	case PTRACE_GETSIGINFO:
384	ret = ptrace_getsiginfo(child, (siginfo_t __user *) data);
385	break;
386	case PTRACE_SETSIGINFO:
387	ret = ptrace_setsiginfo(child, (siginfo_t __user *) data);
388	break;
389	default:
390	break;
391	}
392
393	return ret;
394	}
481bed45	395
6b9c7ed8 CH	396	/**
	397	* ptrace_traceme -- helper for PTRACE_TRACEME
	398	*
	399	* Performs checks and sets PT_PTRACED.
	400	* Should be used by all ptrace implementations for PTRACE_TRACEME.
	401	*/
	402	int ptrace_traceme(void)
481bed45	403	{
f5b40e36	404	int ret = -EPERM;
481bed45 CH	405
481bed45 CH	406	/*
6b9c7ed8 CH	407	* Are we already being traced?
6b9c7ed8 CH	408	*/
f5b40e36 LT	409	task_lock(current);
	410	if (!(current->ptrace & PT_PTRACED)) {
	411	ret = security_ptrace(current->parent, current);
	412	/*
	413	* Set the ptrace bit in the process ptrace flags.
	414	*/
	415	if (!ret)
	416	current->ptrace \|= PT_PTRACED;
	417	}
	418	task_unlock(current);
	419	return ret;
6b9c7ed8	420	}
481bed45	421
6b9c7ed8 CH	422	/**
	423	* ptrace_get_task_struct -- grab a task struct reference for ptrace
	424	* @pid: process id to grab a task_struct reference of
	425	*
	426	* This function is a helper for ptrace implementations. It checks
	427	* permissions and then grabs a task struct for use of the actual
	428	* ptrace implementation.
	429	*
	430	* Returns the task_struct for @pid or an ERR_PTR() on failure.
	431	*/
	432	struct task_struct *ptrace_get_task_struct(pid_t pid)
	433	{
	434	struct task_struct *child;
481bed45 CH	435
481bed45 CH	436	/*
6b9c7ed8	437	* Tracing init is not allowed.
481bed45 CH	438	*/
481bed45 CH	439	if (pid == 1)
6b9c7ed8	440	return ERR_PTR(-EPERM);
481bed45	441
481bed45 CH	442	read_lock(&tasklist_lock);
	443	child = find_task_by_pid(pid);
	444	if (child)
	445	get_task_struct(child);
f400e198	446
481bed45 CH	447	read_unlock(&tasklist_lock);
481bed45 CH	448	if (!child)
6b9c7ed8 CH	449	return ERR_PTR(-ESRCH);
6b9c7ed8 CH	450	return child;
481bed45 CH	451	}
481bed45 CH	452
6b9c7ed8	453	#ifndef __ARCH_SYS_PTRACE
481bed45 CH	454	asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
	455	{
	456	struct task_struct *child;
	457	long ret;
	458
	459	/*
	460	* This lock_kernel fixes a subtle race with suid exec
	461	*/
	462	lock_kernel();
6b9c7ed8 CH	463	if (request == PTRACE_TRACEME) {
6b9c7ed8 CH	464	ret = ptrace_traceme();
481bed45	465	goto out;
6b9c7ed8 CH	466	}
	467
	468	child = ptrace_get_task_struct(pid);
	469	if (IS_ERR(child)) {
	470	ret = PTR_ERR(child);
	471	goto out;
	472	}
481bed45 CH	473
	474	if (request == PTRACE_ATTACH) {
	475	ret = ptrace_attach(child);
005f18df	476	goto out_put_task_struct;
481bed45 CH	477	}
	478
	479	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	480	if (ret < 0)
	481	goto out_put_task_struct;
	482
	483	ret = arch_ptrace(child, request, addr, data);
	484	if (ret < 0)
	485	goto out_put_task_struct;
	486
	487	out_put_task_struct:
	488	put_task_struct(child);
	489	out:
	490	unlock_kernel();
	491	return ret;
	492	}
	493	#endif /* __ARCH_SYS_PTRACE */
76647323 AD	494
	495	int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data)
	496	{
	497	unsigned long tmp;
	498	int copied;
	499
	500	copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
	501	if (copied != sizeof(tmp))
	502	return -EIO;
	503	return put_user(tmp, (unsigned long __user *)data);
	504	}
f284ce72 AD	505
	506	int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
	507	{
	508	int copied;
	509
	510	copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
	511	return (copied == sizeof(data)) ? 0 : -EIO;
	512	}