97 lines
2.4 KiB
C
97 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* syscall_nt.c - checks syscalls with NT set
|
|
* Copyright (c) 2014-2015 Andrew Lutomirski
|
|
*
|
|
* Some obscure user-space code requires the ability to make system calls
|
|
* with FLAGS.NT set. Make sure it works.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <unistd.h>
|
|
#include <string.h>
|
|
#include <signal.h>
|
|
#include <err.h>
|
|
#include <sys/syscall.h>
|
|
|
|
#include "helpers.h"
|
|
|
|
static unsigned int nerrs;
|
|
|
|
static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
|
|
int flags)
|
|
{
|
|
struct sigaction sa;
|
|
memset(&sa, 0, sizeof(sa));
|
|
sa.sa_sigaction = handler;
|
|
sa.sa_flags = SA_SIGINFO | flags;
|
|
sigemptyset(&sa.sa_mask);
|
|
if (sigaction(sig, &sa, 0))
|
|
err(1, "sigaction");
|
|
}
|
|
|
|
static void sigtrap(int sig, siginfo_t *si, void *ctx_void)
|
|
{
|
|
}
|
|
|
|
static void do_it(unsigned long extraflags)
|
|
{
|
|
unsigned long flags;
|
|
|
|
set_eflags(get_eflags() | extraflags);
|
|
syscall(SYS_getpid);
|
|
flags = get_eflags();
|
|
set_eflags(X86_EFLAGS_IF | X86_EFLAGS_FIXED);
|
|
if ((flags & extraflags) == extraflags) {
|
|
printf("[OK]\tThe syscall worked and flags are still set\n");
|
|
} else {
|
|
printf("[FAIL]\tThe syscall worked but flags were cleared (flags = 0x%lx but expected 0x%lx set)\n",
|
|
flags, extraflags);
|
|
nerrs++;
|
|
}
|
|
}
|
|
|
|
int main(void)
|
|
{
|
|
printf("[RUN]\tSet NT and issue a syscall\n");
|
|
do_it(X86_EFLAGS_NT);
|
|
|
|
printf("[RUN]\tSet AC and issue a syscall\n");
|
|
do_it(X86_EFLAGS_AC);
|
|
|
|
printf("[RUN]\tSet NT|AC and issue a syscall\n");
|
|
do_it(X86_EFLAGS_NT | X86_EFLAGS_AC);
|
|
|
|
/*
|
|
* Now try it again with TF set -- TF forces returns via IRET in all
|
|
* cases except non-ptregs-using 64-bit full fast path syscalls.
|
|
*/
|
|
|
|
sethandler(SIGTRAP, sigtrap, 0);
|
|
|
|
printf("[RUN]\tSet TF and issue a syscall\n");
|
|
do_it(X86_EFLAGS_TF);
|
|
|
|
printf("[RUN]\tSet NT|TF and issue a syscall\n");
|
|
do_it(X86_EFLAGS_NT | X86_EFLAGS_TF);
|
|
|
|
printf("[RUN]\tSet AC|TF and issue a syscall\n");
|
|
do_it(X86_EFLAGS_AC | X86_EFLAGS_TF);
|
|
|
|
printf("[RUN]\tSet NT|AC|TF and issue a syscall\n");
|
|
do_it(X86_EFLAGS_NT | X86_EFLAGS_AC | X86_EFLAGS_TF);
|
|
|
|
/*
|
|
* Now try DF. This is evil and it's plausible that we will crash
|
|
* glibc, but glibc would have to do something rather surprising
|
|
* for this to happen.
|
|
*/
|
|
printf("[RUN]\tSet DF and issue a syscall\n");
|
|
do_it(X86_EFLAGS_DF);
|
|
|
|
printf("[RUN]\tSet TF|DF and issue a syscall\n");
|
|
do_it(X86_EFLAGS_TF | X86_EFLAGS_DF);
|
|
|
|
return nerrs == 0 ? 0 : 1;
|
|
}
|