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/*
* 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);
}
/*
* 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 ((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
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