linux-stable/arch/tile/kernel/ptrace.c
Chris Metcalf 1deb9c5dfb arch/tile: don't allow user code to set the PL via ptrace or signal return
The kernel was allowing any component of the pt_regs to be updated either
by signal handlers writing to the stack, or by processes writing via
PTRACE_POKEUSR or PTRACE_SETREGS, which meant they could set their PL
up from 0 to 1 and get access to kernel code and data (or, in practice,
cause a kernel panic).  We now always reset the ex1 field, allowing the
user to set their ICS bit only.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
2010-11-01 15:31:17 -04:00

205 lines
5.1 KiB
C

/*
* Copyright 2010 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* Copied from i386: Ross Biro 1/23/92
*/
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/kprobes.h>
#include <linux/compat.h>
#include <linux/uaccess.h>
#include <asm/traps.h>
void user_enable_single_step(struct task_struct *child)
{
set_tsk_thread_flag(child, TIF_SINGLESTEP);
}
void user_disable_single_step(struct task_struct *child)
{
clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}
/*
* Called by kernel/ptrace.c when detaching..
*/
void ptrace_disable(struct task_struct *child)
{
clear_tsk_thread_flag(child, TIF_SINGLESTEP);
/*
* These two are currently unused, but will be set by arch_ptrace()
* and used in the syscall assembly when we do support them.
*/
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
}
long arch_ptrace(struct task_struct *child, long request,
unsigned long addr, unsigned long data)
{
unsigned long __user *datap = (long __user __force *)data;
unsigned long tmp;
long ret = -EIO;
char *childreg;
struct pt_regs copyregs;
int ex1_offset;
switch (request) {
case PTRACE_PEEKUSR: /* Read register from pt_regs. */
if (addr >= PTREGS_SIZE)
break;
childreg = (char *)task_pt_regs(child) + addr;
#ifdef CONFIG_COMPAT
if (is_compat_task()) {
if (addr & (sizeof(compat_long_t)-1))
break;
ret = put_user(*(compat_long_t *)childreg,
(compat_long_t __user *)datap);
} else
#endif
{
if (addr & (sizeof(long)-1))
break;
ret = put_user(*(long *)childreg, datap);
}
break;
case PTRACE_POKEUSR: /* Write register in pt_regs. */
if (addr >= PTREGS_SIZE)
break;
childreg = (char *)task_pt_regs(child) + addr;
/* Guard against overwrites of the privilege level. */
ex1_offset = PTREGS_OFFSET_EX1;
#if defined(CONFIG_COMPAT) && defined(__BIG_ENDIAN)
if (is_compat_task()) /* point at low word */
ex1_offset += sizeof(compat_long_t);
#endif
if (addr == ex1_offset)
data = PL_ICS_EX1(USER_PL, EX1_ICS(data));
#ifdef CONFIG_COMPAT
if (is_compat_task()) {
if (addr & (sizeof(compat_long_t)-1))
break;
*(compat_long_t *)childreg = data;
} else
#endif
{
if (addr & (sizeof(long)-1))
break;
*(long *)childreg = data;
}
ret = 0;
break;
case PTRACE_GETREGS: /* Get all registers from the child. */
if (copy_to_user(datap, task_pt_regs(child),
sizeof(struct pt_regs)) == 0) {
ret = 0;
}
break;
case PTRACE_SETREGS: /* Set all registers in the child. */
if (copy_from_user(&copyregs, datap,
sizeof(struct pt_regs)) == 0) {
copyregs.ex1 =
PL_ICS_EX1(USER_PL, EX1_ICS(copyregs.ex1));
*task_pt_regs(child) = copyregs;
ret = 0;
}
break;
case PTRACE_GETFPREGS: /* Get the child FPU state. */
case PTRACE_SETFPREGS: /* Set the child FPU state. */
break;
case PTRACE_SETOPTIONS:
/* Support TILE-specific ptrace options. */
child->ptrace &= ~PT_TRACE_MASK_TILE;
tmp = data & PTRACE_O_MASK_TILE;
data &= ~PTRACE_O_MASK_TILE;
ret = ptrace_request(child, request, addr, data);
if (tmp & PTRACE_O_TRACEMIGRATE)
child->ptrace |= PT_TRACE_MIGRATE;
break;
default:
#ifdef CONFIG_COMPAT
if (task_thread_info(current)->status & TS_COMPAT) {
ret = compat_ptrace_request(child, request,
addr, data);
break;
}
#endif
ret = ptrace_request(child, request, addr, data);
break;
}
return ret;
}
#ifdef CONFIG_COMPAT
/* Not used; we handle compat issues in arch_ptrace() directly. */
long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
compat_ulong_t addr, compat_ulong_t data)
{
BUG();
}
#endif
void do_syscall_trace(void)
{
if (!test_thread_flag(TIF_SYSCALL_TRACE))
return;
if (!(current->ptrace & PT_PTRACED))
return;
/*
* The 0x80 provides a way for the tracing parent to distinguish
* between a syscall stop and SIGTRAP delivery
*/
ptrace_notify(SIGTRAP|((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
/*
* this isn't the same as continuing with a signal, but it will do
* for normal use. strace only continues with a signal if the
* stopping signal is not SIGTRAP. -brl
*/
if (current->exit_code) {
send_sig(current->exit_code, current, 1);
current->exit_code = 0;
}
}
void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
{
struct siginfo info;
memset(&info, 0, sizeof(info));
info.si_signo = SIGTRAP;
info.si_code = TRAP_BRKPT;
info.si_addr = (void __user *) regs->pc;
/* Send us the fakey SIGTRAP */
force_sig_info(SIGTRAP, &info, tsk);
}
/* Handle synthetic interrupt delivered only by the simulator. */
void __kprobes do_breakpoint(struct pt_regs* regs, int fault_num)
{
send_sigtrap(current, regs, fault_num);
}