/* * 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;}