(2006-08-06) rescue-bootcd

extra/linux-2.6.10/kernel/ptrace.c

@@ -0,0 +1,362 @@
+/*
+ * 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 <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);
+}
+ 
+static inline int pending_resume_signal(struct sigpending *pending)
+{
+#define M(sig) (1UL << ((sig)-1))
+	return sigtestsetmask(&pending->signal, M(SIGCONT) | M(SIGKILL));
+}
+
+/*
+ * 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))
+		return;
+	list_del_init(&child->ptrace_list);
+	REMOVE_LINKS(child);
+	child->parent = child->real_parent;
+	SET_LINKS(child);
+
+	if (child->state == TASK_TRACED) {
+		/*
+		 * 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.
+		 */
+		spin_lock(&child->sighand->siglock);
+		child->state = TASK_STOPPED;
+		if (pending_resume_signal(&child->pending) ||
+		    pending_resume_signal(&child->signal->shared_pending)) {
+			signal_wake_up(child, 1);
+		}
+		spin_unlock(&child->sighand->siglock);
+	}
+}
+
+/*
+ * 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;
+	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 ((unsigned long) data > _NSIG)
+		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)
+{
+	if (child->last_siginfo == NULL)
+		return -EINVAL;
+	return copy_siginfo_to_user(data, child->last_siginfo);
+}
+
+static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data)
+{
+	if (child->last_siginfo == NULL)
+		return -EINVAL;
+	if (copy_from_user(child->last_siginfo, data, sizeof (siginfo_t)) != 0)
+		return -EFAULT;
+	return 0;
+}
+
+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;
+}