kernel/ptrace.c - maze/linux - Git at Google

 /*
  * 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;
 }
	/*
	* 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;
	}