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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/sched.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/smp_lock.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
/*
* Check that we have indeed attached to the thing..
*/
int ptrace_check_attach(struct task_struct *child, int kill)
{
if (!(child->ptrace & PT_PTRACED))
return -ESRCH;
if (child->p_pptr != current)
return -ESRCH;
if (!kill) {
if (child->state != TASK_STOPPED)
return -ESRCH;
#ifdef CONFIG_SMP
/* Make sure the child gets off its CPU.. */
for (;;) {
task_lock(child);
if (!task_has_cpu(child))
break;
task_unlock(child);
do {
if (child->state != TASK_STOPPED)
return -ESRCH;
barrier();
cpu_relax();
} while (task_has_cpu(child));
}
task_unlock(child);
#endif
}
/* All systems go.. */
return 0;
}
int ptrace_attach(struct task_struct *task)
{
task_lock(task);
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) ||
(!cap_issubset(task->cap_permitted, current->cap_permitted)) ||
(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;
/* Go */
task->ptrace |= PT_PTRACED;
if (capable(CAP_SYS_PTRACE))
task->ptrace |= PT_PTRACE_CAP;
task_unlock(task);
write_lock_irq(&tasklist_lock);
if (task->p_pptr != current) {
REMOVE_LINKS(task);
task->p_pptr = current;
SET_LINKS(task);
}
write_unlock_irq(&tasklist_lock);
send_sig(SIGSTOP, task, 1);
return 0;
bad:
task_unlock(task);
return -EPERM;
}
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->ptrace = 0;
child->exit_code = data;
write_lock_irq(&tasklist_lock);
REMOVE_LINKS(child);
child->p_pptr = child->p_opptr;
SET_LINKS(child);
write_unlock_irq(&tasklist_lock);
/* .. and wake it up. */
wake_up_process(child);
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;
/* Worry about races with exit() */
task_lock(tsk);
mm = tsk->mm;
if (mm)
atomic_inc(&mm->mm_users);
task_unlock(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(current, 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;
flush_cache_page(vma, addr);
maddr = kmap(page);
if (write) {
memcpy(maddr + offset, buf, bytes);
flush_page_to_ram(page);
flush_icache_page(vma, page);
} else {
memcpy(buf, maddr + offset, bytes);
flush_page_to_ram(page);
}
kunmap(page);
put_page(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 *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 * 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;
}
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