[linux-2.6-block.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 <linux/pid_namespace.h>
#include <linux/syscalls.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 (task_is_traced(child)) {
		if (child->signal->flags & SIGNAL_STOP_STOPPED) {
			__set_task_state(child, 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 (ptrace_reparented(child)) {
		list_del_init(&child->ptrace_list);
		remove_parent(child);
		child->parent = child->real_parent;
		add_parent(child);
	}

	if (task_is_traced(child))
		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) {
		ret = 0;
		/*
		 * child->sighand can't be NULL, release_task()
		 * does ptrace_unlink() before __exit_signal().
		 */
		spin_lock_irq(&child->sighand->siglock);
		if (task_is_stopped(child))
			child->state = TASK_TRACED;
		else if (!task_is_traced(child) && !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_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 = __ptrace_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 (same_thread_group(task, current))
		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 = __ptrace_may_attach(task);
	if (retval)
		goto bad;

	/* Go */
	task->ptrace |= PT_PTRACED;
	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 *info)
{
	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)) {
			*info = *child->last_siginfo;
			error = 0;
		}
		spin_unlock_irq(&child->sighand->siglock);
	}
	read_unlock(&tasklist_lock);
	return error;
}

static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
{
	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)) {
			*child->last_siginfo = *info;
			error = 0;
		}
		spin_unlock_irq(&child->sighand->siglock);
	}
	read_unlock(&tasklist_lock);
	return error;
}


#ifdef PTRACE_SINGLESTEP
#define is_singlestep(request)		((request) == PTRACE_SINGLESTEP)
#else
#define is_singlestep(request)		0
#endif

#ifdef PTRACE_SINGLEBLOCK
#define is_singleblock(request)		((request) == PTRACE_SINGLEBLOCK)
#else
#define is_singleblock(request)		0
#endif

#ifdef PTRACE_SYSEMU
#define is_sysemu_singlestep(request)	((request) == PTRACE_SYSEMU_SINGLESTEP)
#else
#define is_sysemu_singlestep(request)	0
#endif

static int ptrace_resume(struct task_struct *child, long request, long data)
{
	if (!valid_signal(data))
		return -EIO;

	if (request == PTRACE_SYSCALL)
		set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	else
		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

#ifdef TIF_SYSCALL_EMU
	if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
		set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
	else
		clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
#endif

	if (is_singleblock(request)) {
		if (unlikely(!arch_has_block_step()))
			return -EIO;
		user_enable_block_step(child);
	} else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
		if (unlikely(!arch_has_single_step()))
			return -EIO;
		user_enable_single_step(child);
	}
	else
		user_disable_single_step(child);

	child->exit_code = data;
	wake_up_process(child);

	return 0;
}

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

	switch (request) {
	case PTRACE_PEEKTEXT:
	case PTRACE_PEEKDATA:
		return generic_ptrace_peekdata(child, addr, data);
	case PTRACE_POKETEXT:
	case PTRACE_POKEDATA:
		return generic_ptrace_pokedata(child, addr, data);

#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);
		if (!ret)
			ret = copy_siginfo_to_user((siginfo_t __user *) data,
						   &siginfo);
		break;

	case PTRACE_SETSIGINFO:
		if (copy_from_user(&siginfo, (siginfo_t __user *) data,
				   sizeof siginfo))
			ret = -EFAULT;
		else
			ret = ptrace_setsiginfo(child, &siginfo);
		break;

	case PTRACE_DETACH:	 /* detach a process that was attached. */
		ret = ptrace_detach(child, data);
		break;

#ifdef PTRACE_SINGLESTEP
	case PTRACE_SINGLESTEP:
#endif
#ifdef PTRACE_SINGLEBLOCK
	case PTRACE_SINGLEBLOCK:
#endif
#ifdef PTRACE_SYSEMU
	case PTRACE_SYSEMU:
	case PTRACE_SYSEMU_SINGLESTEP:
#endif
	case PTRACE_SYSCALL:
	case PTRACE_CONT:
		return ptrace_resume(child, request, data);

	case PTRACE_KILL:
		if (child->exit_state)	/* already dead */
			return 0;
		return ptrace_resume(child, request, SIGKILL);

	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_vpid(pid);
	if (child)
		get_task_struct(child);

	read_unlock(&tasklist_lock);
	if (!child)
		return ERR_PTR(-ESRCH);
	return child;
}

#ifndef arch_ptrace_attach
#define arch_ptrace_attach(child)	do { } while (0)
#endif

#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();
		if (!ret)
			arch_ptrace_attach(current);
		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);
		/*
		 * Some architectures need to do book-keeping after
		 * a ptrace attach.
		 */
		if (!ret)
			arch_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;
}

#if defined CONFIG_COMPAT && defined __ARCH_WANT_COMPAT_SYS_PTRACE
#include <linux/compat.h>

int compat_ptrace_request(struct task_struct *child, compat_long_t request,
			  compat_ulong_t addr, compat_ulong_t data)
{
	compat_ulong_t __user *datap = compat_ptr(data);
	compat_ulong_t word;
	siginfo_t siginfo;
	int ret;

	switch (request) {
	case PTRACE_PEEKTEXT:
	case PTRACE_PEEKDATA:
		ret = access_process_vm(child, addr, &word, sizeof(word), 0);
		if (ret != sizeof(word))
			ret = -EIO;
		else
			ret = put_user(word, datap);
		break;

	case PTRACE_POKETEXT:
	case PTRACE_POKEDATA:
		ret = access_process_vm(child, addr, &data, sizeof(data), 1);
		ret = (ret != sizeof(data) ? -EIO : 0);
		break;

	case PTRACE_GETEVENTMSG:
		ret = put_user((compat_ulong_t) child->ptrace_message, datap);
		break;

	case PTRACE_GETSIGINFO:
		ret = ptrace_getsiginfo(child, &siginfo);
		if (!ret)
			ret = copy_siginfo_to_user32(
				(struct compat_siginfo __user *) datap,
				&siginfo);
		break;

	case PTRACE_SETSIGINFO:
		memset(&siginfo, 0, sizeof siginfo);
		if (copy_siginfo_from_user32(
			    &siginfo, (struct compat_siginfo __user *) datap))
			ret = -EFAULT;
		else
			ret = ptrace_setsiginfo(child, &siginfo);
		break;

	default:
		ret = ptrace_request(child, request, addr, data);
	}

	return ret;
}

asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
				  compat_long_t addr, compat_long_t 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);
		/*
		 * Some architectures need to do book-keeping after
		 * a ptrace attach.
		 */
		if (!ret)
			arch_ptrace_attach(child);
		goto out_put_task_struct;
	}

	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	if (!ret)
		ret = compat_arch_ptrace(child, request, addr, data);

 out_put_task_struct:
	put_task_struct(child);
 out:
	unlock_kernel();
	return ret;
}
#endif	/* CONFIG_COMPAT && __ARCH_WANT_COMPAT_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>
a5cb013d	21	#include <linux/audit.h>
b488893a	22	#include <linux/pid_namespace.h>
f17d30a8	23	#include <linux/syscalls.h>
1da177e4 LT	24
	25	#include <asm/pgtable.h>
	26	#include <asm/uaccess.h>
	27
	28	/*
	29	* ptrace a task: make the debugger its new parent and
	30	* move it to the ptrace list.
	31	*
	32	* Must be called with the tasklist lock write-held.
	33	*/
36c8b586	34	void __ptrace_link(struct task_struct child, struct task_struct new_parent)
1da177e4	35	{
524223ca	36	BUG_ON(!list_empty(&child->ptrace_list));
1da177e4 LT	37	if (child->parent == new_parent)
	38	return;
	39	list_add(&child->ptrace_list, &child->parent->ptrace_children);
9b678ece	40	remove_parent(child);
1da177e4	41	child->parent = new_parent;
9b678ece	42	add_parent(child);
1da177e4 LT	43	}
	44
	45	/*
	46	* Turn a tracing stop into a normal stop now, since with no tracer there
	47	* would be no way to wake it up with SIGCONT or SIGKILL. If there was a
	48	* signal sent that would resume the child, but didn't because it was in
	49	* TASK_TRACED, resume it now.
	50	* Requires that irqs be disabled.
	51	*/
36c8b586	52	void ptrace_untrace(struct task_struct *child)
1da177e4 LT	53	{
1da177e4 LT	54	spin_lock(&child->sighand->siglock);
6618a3e2	55	if (task_is_traced(child)) {
1da177e4	56	if (child->signal->flags & SIGNAL_STOP_STOPPED) {
d9ae90ac	57	__set_task_state(child, TASK_STOPPED);
1da177e4 LT	58	} else {
	59	signal_wake_up(child, 1);
	60	}
	61	}
	62	spin_unlock(&child->sighand->siglock);
	63	}
	64
	65	/*
	66	* unptrace a task: move it back to its original parent and
	67	* remove it from the ptrace list.
	68	*
	69	* Must be called with the tasklist lock write-held.
	70	*/
36c8b586	71	void __ptrace_unlink(struct task_struct *child)
1da177e4	72	{
5ecfbae0 ON	73	BUG_ON(!child->ptrace);
5ecfbae0 ON	74
1da177e4	75	child->ptrace = 0;
68cb9478	76	if (ptrace_reparented(child)) {
1da177e4	77	list_del_init(&child->ptrace_list);
9b678ece	78	remove_parent(child);
1da177e4	79	child->parent = child->real_parent;
9b678ece	80	add_parent(child);
1da177e4 LT	81	}
1da177e4 LT	82
6618a3e2	83	if (task_is_traced(child))
e57a5059	84	ptrace_untrace(child);
1da177e4 LT	85	}
	86
	87	/*
	88	* Check that we have indeed attached to the thing..
	89	*/
	90	int ptrace_check_attach(struct task_struct *child, int kill)
	91	{
	92	int ret = -ESRCH;
	93
	94	/*
	95	* We take the read lock around doing both checks to close a
	96	* possible race where someone else was tracing our child and
	97	* detached between these two checks. After this locked check,
	98	* we are sure that this is our traced child and that can only
	99	* be changed by us so it's not changing right after this.
	100	*/
	101	read_lock(&tasklist_lock);
c0c0b649	102	if ((child->ptrace & PT_PTRACED) && child->parent == current) {
1da177e4	103	ret = 0;
c0c0b649 ON	104	/*
	105	* child->sighand can't be NULL, release_task()
	106	* does ptrace_unlink() before __exit_signal().
	107	*/
1da177e4	108	spin_lock_irq(&child->sighand->siglock);
d9ae90ac	109	if (task_is_stopped(child))
1da177e4	110	child->state = TASK_TRACED;
d9ae90ac	111	else if (!task_is_traced(child) && !kill)
1da177e4	112	ret = -ESRCH;
1da177e4 LT	113	spin_unlock_irq(&child->sighand->siglock);
	114	}
	115	read_unlock(&tasklist_lock);
	116
d9ae90ac	117	if (!ret && !kill)
1da177e4	118	wait_task_inactive(child);
1da177e4 LT	119
	120	/* All systems go.. */
	121	return ret;
	122	}
	123
831830b5	124	int __ptrace_may_attach(struct task_struct *task)
ab8d11be	125	{
df26c40e EB	126	/* May we inspect the given task?
	127	* This check is used both for attaching with ptrace
	128	* and for allowing access to sensitive information in /proc.
	129	*
	130	* ptrace_attach denies several cases that /proc allows
	131	* because setting up the necessary parent/child relationship
	132	* or halting the specified task is impossible.
	133	*/
	134	int dumpable = 0;
	135	/* Don't let security modules deny introspection */
	136	if (task == current)
	137	return 0;
ab8d11be MS	138	if (((current->uid != task->euid) \|\|
	139	(current->uid != task->suid) \|\|
	140	(current->uid != task->uid) \|\|
	141	(current->gid != task->egid) \|\|
	142	(current->gid != task->sgid) \|\|
	143	(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
	144	return -EPERM;
	145	smp_rmb();
df26c40e	146	if (task->mm)
6c5d5238	147	dumpable = get_dumpable(task->mm);
df26c40e	148	if (!dumpable && !capable(CAP_SYS_PTRACE))
ab8d11be MS	149	return -EPERM;
	150
	151	return security_ptrace(current, task);
	152	}
	153
	154	int ptrace_may_attach(struct task_struct *task)
	155	{
	156	int err;
	157	task_lock(task);
831830b5	158	err = __ptrace_may_attach(task);
ab8d11be MS	159	task_unlock(task);
	160	return !err;
	161	}
	162
1da177e4 LT	163	int ptrace_attach(struct task_struct *task)
	164	{
	165	int retval;
6175ecfe	166	unsigned long flags;
f5b40e36	167
a5cb013d AV	168	audit_ptrace(task);
a5cb013d AV	169
1da177e4 LT	170	retval = -EPERM;
1da177e4 LT	171	if (task->pid <= 1)
f5b40e36	172	goto out;
bac0abd6	173	if (same_thread_group(task, current))
f5b40e36 LT	174	goto out;
f5b40e36 LT	175
f358166a LT	176	repeat:
	177	/*
	178	* Nasty, nasty.
	179	*
	180	* We want to hold both the task-lock and the
	181	* tasklist_lock for writing at the same time.
	182	* But that's against the rules (tasklist_lock
	183	* is taken for reading by interrupts on other
	184	* cpu's that may have task_lock).
	185	*/
f5b40e36	186	task_lock(task);
6175ecfe	187	if (!write_trylock_irqsave(&tasklist_lock, flags)) {
f358166a LT	188	task_unlock(task);
	189	do {
	190	cpu_relax();
	191	} while (!write_can_lock(&tasklist_lock));
	192	goto repeat;
	193	}
f5b40e36	194
df26c40e EB	195	if (!task->mm)
df26c40e EB	196	goto bad;
1da177e4 LT	197	/* the same process cannot be attached many times */
	198	if (task->ptrace & PT_PTRACED)
	199	goto bad;
b8c9a187	200	retval = __ptrace_may_attach(task);
1da177e4 LT	201	if (retval)
	202	goto bad;
	203
	204	/* Go */
6b39c7bf	205	task->ptrace \|= PT_PTRACED;
1da177e4 LT	206	if (capable(CAP_SYS_PTRACE))
1da177e4 LT	207	task->ptrace \|= PT_PTRACE_CAP;
1da177e4	208
1da177e4	209	__ptrace_link(task, current);
1da177e4 LT	210
1da177e4 LT	211	force_sig_specific(SIGSTOP, task);
1da177e4 LT	212
1da177e4 LT	213	bad:
6175ecfe	214	write_unlock_irqrestore(&tasklist_lock, flags);
1da177e4	215	task_unlock(task);
f5b40e36	216	out:
1da177e4 LT	217	return retval;
	218	}
	219
d5f70c00	220	static inline void __ptrace_detach(struct task_struct *child, unsigned int data)
5ecfbae0 ON	221	{
	222	child->exit_code = data;
	223	/* .. re-parent .. */
	224	__ptrace_unlink(child);
	225	/* .. and wake it up. */
	226	if (child->exit_state != EXIT_ZOMBIE)
	227	wake_up_process(child);
	228	}
	229
1da177e4 LT	230	int ptrace_detach(struct task_struct *child, unsigned int data)
1da177e4 LT	231	{
7ed20e1a	232	if (!valid_signal(data))
5ecfbae0	233	return -EIO;
1da177e4 LT	234
	235	/* Architecture-specific hardware disable .. */
	236	ptrace_disable(child);
7d941432	237	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
1da177e4	238
1da177e4	239	write_lock_irq(&tasklist_lock);
d5f70c00	240	/* protect against de_thread()->release_task() */
5ecfbae0 ON	241	if (child->ptrace)
5ecfbae0 ON	242	__ptrace_detach(child, data);
1da177e4 LT	243	write_unlock_irq(&tasklist_lock);
	244
	245	return 0;
	246	}
	247
1da177e4 LT	248	int ptrace_readdata(struct task_struct tsk, unsigned long src, char __user dst, int len)
	249	{
	250	int copied = 0;
	251
	252	while (len > 0) {
	253	char buf[128];
	254	int this_len, retval;
	255
	256	this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
	257	retval = access_process_vm(tsk, src, buf, this_len, 0);
	258	if (!retval) {
	259	if (copied)
	260	break;
	261	return -EIO;
	262	}
	263	if (copy_to_user(dst, buf, retval))
	264	return -EFAULT;
	265	copied += retval;
	266	src += retval;
	267	dst += retval;
	268	len -= retval;
	269	}
	270	return copied;
	271	}
	272
	273	int ptrace_writedata(struct task_struct tsk, char __user src, unsigned long dst, int len)
	274	{
	275	int copied = 0;
	276
	277	while (len > 0) {
	278	char buf[128];
	279	int this_len, retval;
	280
	281	this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
	282	if (copy_from_user(buf, src, this_len))
	283	return -EFAULT;
	284	retval = access_process_vm(tsk, dst, buf, this_len, 1);
	285	if (!retval) {
	286	if (copied)
	287	break;
	288	return -EIO;
	289	}
	290	copied += retval;
	291	src += retval;
	292	dst += retval;
	293	len -= retval;
	294	}
	295	return copied;
	296	}
	297
	298	static int ptrace_setoptions(struct task_struct *child, long data)
	299	{
	300	child->ptrace &= ~PT_TRACE_MASK;
	301
	302	if (data & PTRACE_O_TRACESYSGOOD)
	303	child->ptrace \|= PT_TRACESYSGOOD;
	304
	305	if (data & PTRACE_O_TRACEFORK)
	306	child->ptrace \|= PT_TRACE_FORK;
	307
	308	if (data & PTRACE_O_TRACEVFORK)
	309	child->ptrace \|= PT_TRACE_VFORK;
	310
	311	if (data & PTRACE_O_TRACECLONE)
312	child->ptrace \|= PT_TRACE_CLONE;
313
314	if (data & PTRACE_O_TRACEEXEC)
315	child->ptrace \|= PT_TRACE_EXEC;
316
317	if (data & PTRACE_O_TRACEVFORKDONE)
318	child->ptrace \|= PT_TRACE_VFORK_DONE;
319
320	if (data & PTRACE_O_TRACEEXIT)
321	child->ptrace \|= PT_TRACE_EXIT;
322
323	return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
324	}
325
e16b2781	326	static int ptrace_getsiginfo(struct task_struct child, siginfo_t info)
1da177e4	327	{
1da177e4 LT	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)) {
e16b2781	335	info = child->last_siginfo;
1da177e4 LT	336	error = 0;
	337	}
	338	spin_unlock_irq(&child->sighand->siglock);
	339	}
	340	read_unlock(&tasklist_lock);
1da177e4 LT	341	return error;
	342	}
	343
e16b2781	344	static int ptrace_setsiginfo(struct task_struct child, const siginfo_t info)
1da177e4	345	{
1da177e4 LT	346	int error = -ESRCH;
1da177e4 LT	347
1da177e4 LT	348	read_lock(&tasklist_lock);
	349	if (likely(child->sighand != NULL)) {
	350	error = -EINVAL;
	351	spin_lock_irq(&child->sighand->siglock);
	352	if (likely(child->last_siginfo != NULL)) {
e16b2781	353	child->last_siginfo = info;
1da177e4 LT	354	error = 0;
	355	}
	356	spin_unlock_irq(&child->sighand->siglock);
	357	}
	358	read_unlock(&tasklist_lock);
	359	return error;
	360	}
	361
36df29d7 RM	362
	363	#ifdef PTRACE_SINGLESTEP
	364	#define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)
	365	#else
	366	#define is_singlestep(request) 0
	367	#endif
	368
5b88abbf RM	369	#ifdef PTRACE_SINGLEBLOCK
	370	#define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK)
	371	#else
	372	#define is_singleblock(request) 0
	373	#endif
	374
36df29d7 RM	375	#ifdef PTRACE_SYSEMU
	376	#define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP)
	377	#else
	378	#define is_sysemu_singlestep(request) 0
	379	#endif
	380
	381	static int ptrace_resume(struct task_struct *child, long request, long data)
	382	{
	383	if (!valid_signal(data))
	384	return -EIO;
	385
	386	if (request == PTRACE_SYSCALL)
	387	set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	388	else
	389	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	390
	391	#ifdef TIF_SYSCALL_EMU
	392	if (request == PTRACE_SYSEMU \|\| request == PTRACE_SYSEMU_SINGLESTEP)
	393	set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
	394	else
	395	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
	396	#endif
	397
5b88abbf RM	398	if (is_singleblock(request)) {
	399	if (unlikely(!arch_has_block_step()))
	400	return -EIO;
	401	user_enable_block_step(child);
	402	} else if (is_singlestep(request) \|\| is_sysemu_singlestep(request)) {
36df29d7 RM	403	if (unlikely(!arch_has_single_step()))
	404	return -EIO;
	405	user_enable_single_step(child);
	406	}
	407	else
	408	user_disable_single_step(child);
	409
	410	child->exit_code = data;
	411	wake_up_process(child);
	412
	413	return 0;
	414	}
	415
1da177e4 LT	416	int ptrace_request(struct task_struct *child, long request,
	417	long addr, long data)
	418	{
	419	int ret = -EIO;
e16b2781	420	siginfo_t siginfo;
1da177e4 LT	421
1da177e4 LT	422	switch (request) {
16c3e389 RM	423	case PTRACE_PEEKTEXT:
	424	case PTRACE_PEEKDATA:
	425	return generic_ptrace_peekdata(child, addr, data);
	426	case PTRACE_POKETEXT:
	427	case PTRACE_POKEDATA:
	428	return generic_ptrace_pokedata(child, addr, data);
	429
1da177e4 LT	430	#ifdef PTRACE_OLDSETOPTIONS
	431	case PTRACE_OLDSETOPTIONS:
	432	#endif
	433	case PTRACE_SETOPTIONS:
	434	ret = ptrace_setoptions(child, data);
	435	break;
	436	case PTRACE_GETEVENTMSG:
	437	ret = put_user(child->ptrace_message, (unsigned long __user *) data);
	438	break;
e16b2781	439
1da177e4	440	case PTRACE_GETSIGINFO:
e16b2781 RM	441	ret = ptrace_getsiginfo(child, &siginfo);
	442	if (!ret)
	443	ret = copy_siginfo_to_user((siginfo_t __user *) data,
	444	&siginfo);
1da177e4	445	break;
e16b2781	446
1da177e4	447	case PTRACE_SETSIGINFO:
e16b2781 RM	448	if (copy_from_user(&siginfo, (siginfo_t __user *) data,
	449	sizeof siginfo))
	450	ret = -EFAULT;
	451	else
	452	ret = ptrace_setsiginfo(child, &siginfo);
1da177e4	453	break;
e16b2781	454
1bcf5482 AD	455	case PTRACE_DETACH: /* detach a process that was attached. */
	456	ret = ptrace_detach(child, data);
	457	break;
36df29d7 RM	458
	459	#ifdef PTRACE_SINGLESTEP
	460	case PTRACE_SINGLESTEP:
	461	#endif
5b88abbf RM	462	#ifdef PTRACE_SINGLEBLOCK
	463	case PTRACE_SINGLEBLOCK:
	464	#endif
36df29d7 RM	465	#ifdef PTRACE_SYSEMU
	466	case PTRACE_SYSEMU:
	467	case PTRACE_SYSEMU_SINGLESTEP:
	468	#endif
	469	case PTRACE_SYSCALL:
	470	case PTRACE_CONT:
	471	return ptrace_resume(child, request, data);
	472
	473	case PTRACE_KILL:
	474	if (child->exit_state) /* already dead */
	475	return 0;
	476	return ptrace_resume(child, request, SIGKILL);
	477
1da177e4 LT	478	default:
	479	break;
	480	}
	481
	482	return ret;
	483	}
481bed45	484
6b9c7ed8 CH	485	/**
	486	* ptrace_traceme -- helper for PTRACE_TRACEME
	487	*
	488	* Performs checks and sets PT_PTRACED.
	489	* Should be used by all ptrace implementations for PTRACE_TRACEME.
	490	*/
	491	int ptrace_traceme(void)
481bed45	492	{
f5b40e36	493	int ret = -EPERM;
481bed45 CH	494
481bed45 CH	495	/*
6b9c7ed8 CH	496	* Are we already being traced?
6b9c7ed8 CH	497	*/
f5b40e36 LT	498	task_lock(current);
	499	if (!(current->ptrace & PT_PTRACED)) {
	500	ret = security_ptrace(current->parent, current);
	501	/*
	502	* Set the ptrace bit in the process ptrace flags.
	503	*/
	504	if (!ret)
	505	current->ptrace \|= PT_PTRACED;
	506	}
	507	task_unlock(current);
	508	return ret;
6b9c7ed8	509	}
481bed45	510
6b9c7ed8 CH	511	/**
	512	* ptrace_get_task_struct -- grab a task struct reference for ptrace
	513	* @pid: process id to grab a task_struct reference of
	514	*
	515	* This function is a helper for ptrace implementations. It checks
	516	* permissions and then grabs a task struct for use of the actual
	517	* ptrace implementation.
	518	*
	519	* Returns the task_struct for @pid or an ERR_PTR() on failure.
	520	*/
	521	struct task_struct *ptrace_get_task_struct(pid_t pid)
	522	{
	523	struct task_struct *child;
481bed45 CH	524
481bed45 CH	525	/*
6b9c7ed8	526	* Tracing init is not allowed.
481bed45 CH	527	*/
481bed45 CH	528	if (pid == 1)
6b9c7ed8	529	return ERR_PTR(-EPERM);
481bed45	530
481bed45	531	read_lock(&tasklist_lock);
228ebcbe	532	child = find_task_by_vpid(pid);
481bed45 CH	533	if (child)
481bed45 CH	534	get_task_struct(child);
f400e198	535
481bed45 CH	536	read_unlock(&tasklist_lock);
481bed45 CH	537	if (!child)
6b9c7ed8 CH	538	return ERR_PTR(-ESRCH);
6b9c7ed8 CH	539	return child;
481bed45 CH	540	}
481bed45 CH	541
0ac15559 CH	542	#ifndef arch_ptrace_attach
	543	#define arch_ptrace_attach(child) do { } while (0)
	544	#endif
	545
6b9c7ed8	546	#ifndef __ARCH_SYS_PTRACE
481bed45 CH	547	asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
	548	{
	549	struct task_struct *child;
	550	long ret;
	551
	552	/*
	553	* This lock_kernel fixes a subtle race with suid exec
	554	*/
	555	lock_kernel();
6b9c7ed8 CH	556	if (request == PTRACE_TRACEME) {
6b9c7ed8 CH	557	ret = ptrace_traceme();
6ea6dd93 HS	558	if (!ret)
6ea6dd93 HS	559	arch_ptrace_attach(current);
481bed45	560	goto out;
6b9c7ed8 CH	561	}
	562
	563	child = ptrace_get_task_struct(pid);
	564	if (IS_ERR(child)) {
	565	ret = PTR_ERR(child);
	566	goto out;
	567	}
481bed45 CH	568
	569	if (request == PTRACE_ATTACH) {
	570	ret = ptrace_attach(child);
0ac15559 CH	571	/*
	572	* Some architectures need to do book-keeping after
	573	* a ptrace attach.
	574	*/
	575	if (!ret)
	576	arch_ptrace_attach(child);
005f18df	577	goto out_put_task_struct;
481bed45 CH	578	}
	579
	580	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	581	if (ret < 0)
	582	goto out_put_task_struct;
	583
	584	ret = arch_ptrace(child, request, addr, data);
	585	if (ret < 0)
	586	goto out_put_task_struct;
	587
	588	out_put_task_struct:
	589	put_task_struct(child);
	590	out:
	591	unlock_kernel();
	592	return ret;
	593	}
	594	#endif /* __ARCH_SYS_PTRACE */
76647323 AD	595
	596	int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data)
	597	{
	598	unsigned long tmp;
	599	int copied;
	600
	601	copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
	602	if (copied != sizeof(tmp))
	603	return -EIO;
	604	return put_user(tmp, (unsigned long __user *)data);
	605	}
f284ce72 AD	606
	607	int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
	608	{
	609	int copied;
	610
	611	copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
	612	return (copied == sizeof(data)) ? 0 : -EIO;
	613	}
032d82d9	614
9d04d928	615	#if defined CONFIG_COMPAT && defined __ARCH_WANT_COMPAT_SYS_PTRACE
032d82d9 RM	616	#include <linux/compat.h>
	617
	618	int compat_ptrace_request(struct task_struct *child, compat_long_t request,
	619	compat_ulong_t addr, compat_ulong_t data)
	620	{
	621	compat_ulong_t __user *datap = compat_ptr(data);
	622	compat_ulong_t word;
e16b2781	623	siginfo_t siginfo;
032d82d9 RM	624	int ret;
	625
	626	switch (request) {
	627	case PTRACE_PEEKTEXT:
	628	case PTRACE_PEEKDATA:
	629	ret = access_process_vm(child, addr, &word, sizeof(word), 0);
	630	if (ret != sizeof(word))
	631	ret = -EIO;
	632	else
	633	ret = put_user(word, datap);
	634	break;
	635
	636	case PTRACE_POKETEXT:
	637	case PTRACE_POKEDATA:
	638	ret = access_process_vm(child, addr, &data, sizeof(data), 1);
	639	ret = (ret != sizeof(data) ? -EIO : 0);
	640	break;
	641
	642	case PTRACE_GETEVENTMSG:
	643	ret = put_user((compat_ulong_t) child->ptrace_message, datap);
	644	break;
	645
e16b2781 RM	646	case PTRACE_GETSIGINFO:
	647	ret = ptrace_getsiginfo(child, &siginfo);
	648	if (!ret)
	649	ret = copy_siginfo_to_user32(
	650	(struct compat_siginfo __user *) datap,
	651	&siginfo);
	652	break;
	653
	654	case PTRACE_SETSIGINFO:
	655	memset(&siginfo, 0, sizeof siginfo);
	656	if (copy_siginfo_from_user32(
	657	&siginfo, (struct compat_siginfo __user *) datap))
	658	ret = -EFAULT;
	659	else
	660	ret = ptrace_setsiginfo(child, &siginfo);
	661	break;
	662
032d82d9 RM	663	default:
	664	ret = ptrace_request(child, request, addr, data);
	665	}
	666
	667	return ret;
	668	}
c269f196	669
c269f196 RM	670	asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
	671	compat_long_t addr, compat_long_t data)
	672	{
	673	struct task_struct *child;
	674	long ret;
	675
	676	/*
	677	* This lock_kernel fixes a subtle race with suid exec
	678	*/
	679	lock_kernel();
	680	if (request == PTRACE_TRACEME) {
	681	ret = ptrace_traceme();
	682	goto out;
	683	}
	684
	685	child = ptrace_get_task_struct(pid);
	686	if (IS_ERR(child)) {
	687	ret = PTR_ERR(child);
	688	goto out;
	689	}
	690
	691	if (request == PTRACE_ATTACH) {
	692	ret = ptrace_attach(child);
	693	/*
	694	* Some architectures need to do book-keeping after
	695	* a ptrace attach.
	696	*/
	697	if (!ret)
	698	arch_ptrace_attach(child);
	699	goto out_put_task_struct;
	700	}
	701
	702	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	703	if (!ret)
	704	ret = compat_arch_ptrace(child, request, addr, data);
	705
	706	out_put_task_struct:
	707	put_task_struct(child);
	708	out:
	709	unlock_kernel();
	710	return ret;
	711	}
9d04d928	712	#endif /* CONFIG_COMPAT && __ARCH_WANT_COMPAT_SYS_PTRACE */