linux/arch/um/kernel/signal.c
Eric W. Biederman c200e4bb44 ptrace/um: Replace PT_DTRACE with TIF_SINGLESTEP
User mode linux is the last user of the PT_DTRACE flag.  Using the flag to indicate
single stepping is a little confusing and worse changing tsk->ptrace without locking
could potentionally cause problems.

So use a thread info flag with a better name instead of flag in tsk->ptrace.

Remove the definition PT_DTRACE as uml is the last user.

Cc: stable@vger.kernel.org
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-3-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-05-11 14:33:33 -05:00

142 lines
3.3 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
*/
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/ftrace.h>
#include <asm/siginfo.h>
#include <asm/signal.h>
#include <asm/unistd.h>
#include <frame_kern.h>
#include <kern_util.h>
#include <os.h>
EXPORT_SYMBOL(block_signals);
EXPORT_SYMBOL(unblock_signals);
void block_signals_trace(void)
{
block_signals();
if (current_thread_info())
trace_hardirqs_off();
}
void unblock_signals_trace(void)
{
if (current_thread_info())
trace_hardirqs_on();
unblock_signals();
}
void um_trace_signals_on(void)
{
if (current_thread_info())
trace_hardirqs_on();
}
void um_trace_signals_off(void)
{
if (current_thread_info())
trace_hardirqs_off();
}
/*
* OK, we're invoking a handler
*/
static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
sigset_t *oldset = sigmask_to_save();
int singlestep = 0;
unsigned long sp;
int err;
if (test_thread_flag(TIF_SINGLESTEP) && (current->ptrace & PT_PTRACED))
singlestep = 1;
/* Did we come from a system call? */
if (PT_REGS_SYSCALL_NR(regs) >= 0) {
/* If so, check system call restarting.. */
switch (PT_REGS_SYSCALL_RET(regs)) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
PT_REGS_SYSCALL_RET(regs) = -EINTR;
break;
case -ERESTARTSYS:
if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
PT_REGS_SYSCALL_RET(regs) = -EINTR;
break;
}
fallthrough;
case -ERESTARTNOINTR:
PT_REGS_RESTART_SYSCALL(regs);
PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
break;
}
}
sp = PT_REGS_SP(regs);
if ((ksig->ka.sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
sp = current->sas_ss_sp + current->sas_ss_size;
#ifdef CONFIG_ARCH_HAS_SC_SIGNALS
if (!(ksig->ka.sa.sa_flags & SA_SIGINFO))
err = setup_signal_stack_sc(sp, ksig, regs, oldset);
else
#endif
err = setup_signal_stack_si(sp, ksig, regs, oldset);
signal_setup_done(err, ksig, singlestep);
}
void do_signal(struct pt_regs *regs)
{
struct ksignal ksig;
int handled_sig = 0;
while (get_signal(&ksig)) {
handled_sig = 1;
/* Whee! Actually deliver the signal. */
handle_signal(&ksig, regs);
}
/* Did we come from a system call? */
if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
/* Restart the system call - no handlers present */
switch (PT_REGS_SYSCALL_RET(regs)) {
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
PT_REGS_RESTART_SYSCALL(regs);
break;
case -ERESTART_RESTARTBLOCK:
PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
PT_REGS_RESTART_SYSCALL(regs);
break;
}
}
/*
* This closes a way to execute a system call on the host. If
* you set a breakpoint on a system call instruction and singlestep
* from it, the tracing thread used to PTRACE_SINGLESTEP the process
* rather than PTRACE_SYSCALL it, allowing the system call to execute
* on the host. The tracing thread will check this flag and
* PTRACE_SYSCALL if necessary.
*/
if (test_thread_flag(TIF_SINGLESTEP))
current->thread.singlestep_syscall =
is_syscall(PT_REGS_IP(&current->thread.regs));
/*
* if there's no signal to deliver, we just put the saved sigmask
* back
*/
if (!handled_sig)
restore_saved_sigmask();
}