/* Copyright (C) 2014 Stony Brook University
This file is part of Graphene Library OS.
Graphene Library OS is free software: you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License
as published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
Graphene Library OS 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. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see . */
/*
* db_signal.c
*
* This file contains APIs to set up handlers of exceptions issued by the
* host, and the methods to pass the exceptions to the upcalls.
*/
#include "pal_linux.h"
#include "api.h"
#include "ecall_types.h"
#include "ocall_types.h"
#include "sgx_internal.h"
#include "pal_linux.h"
#include
#include
#include
#include
#include
#include "sgx_enclave.h"
#if !defined(__i386__)
/* In x86_64 kernels, sigaction is required to have a user-defined
* restorer. Also, they not yet support SA_INFO. The reference:
* http://lxr.linux.no/linux+v2.6.35/arch/x86/kernel/signal.c#L448
*
* / * x86-64 should always use SA_RESTORER. * /
* if (ka->sa.sa_flags & SA_RESTORER) {
* put_user_ex(ka->sa.sa_restorer, &frame->pretcode);
* } else {
* / * could use a vstub here * /
* err |= -EFAULT;
* }
*/
#ifndef SA_RESTORER
#define SA_RESTORER 0x04000000
#endif
#define DEFINE_RESTORE_RT(syscall) DEFINE_RESTORE_RT2(syscall)
#define DEFINE_RESTORE_RT2(syscall) \
__asm__ ( \
" nop\n" \
".align 16\n" \
".LSTART_restore_rt:\n" \
" .type __restore_rt,@function\n" \
"__restore_rt:\n" \
" movq $" #syscall ", %rax\n" \
" syscall\n");
DEFINE_RESTORE_RT(__NR_rt_sigreturn)
/* Workaround for fixing an old GAS (2.27) bug that incorrectly
* omits relocations when referencing this symbol */
__attribute__((visibility("hidden"))) void __restore_rt(void);
#endif
static const int async_signals[] =
{
SIGTERM,
SIGINT,
SIGCONT,
};
static const int nasync_signals = ARRAY_SIZE(async_signals);
int set_sighandler (int * sigs, int nsig, void * handler)
{
struct sigaction action;
action.sa_handler = (void (*)(int)) handler;
action.sa_flags = SA_SIGINFO;
#if !defined(__i386__)
action.sa_flags |= SA_RESTORER;
action.sa_restorer = __restore_rt;
#endif
/* Disallow nested asynchronous signals during enclave exception handling.
*/
__sigemptyset((__sigset_t *) &action.sa_mask);
for (int i = 0; i < nasync_signals; i++)
__sigaddset((__sigset_t *) &action.sa_mask, async_signals[i]);
for (int i = 0 ; i < nsig ; i++) {
if (sigs[i] == SIGCHLD)
action.sa_flags |= SA_NOCLDSTOP|SA_NOCLDWAIT;
#if defined(__i386__)
int ret = INLINE_SYSCALL(sigaction, 3, sigs[i], &action, NULL)
#else
int ret = INLINE_SYSCALL(rt_sigaction, 4, sigs[i], &action, NULL,
sizeof(sigset_t));
#endif
if (IS_ERR(ret))
return -ERRNO(ret);
action.sa_flags &= ~(SA_NOCLDSTOP|SA_NOCLDWAIT);
}
int ret = 0;
__sigset_t mask;
__sigemptyset(&mask);
for (int i = 0 ; i < nsig ; i++)
__sigaddset(&mask, sigs[i]);
#if defined(__i386__)
ret = INLINE_SYSCALL(sigprocmask, 3, SIG_UNBLOCK, &mask, NULL)
#else
ret = INLINE_SYSCALL(rt_sigprocmask, 4, SIG_UNBLOCK, &mask, NULL,
sizeof(sigset_t));
#endif
if (IS_ERR(ret))
return -ERRNO(ret);
return 0;
}
int block_signals (bool block, const int * sigs, int nsig)
{
int how = block? SIG_BLOCK: SIG_UNBLOCK;
int ret = 0;
__sigset_t mask;
__sigemptyset(&mask);
for (int i = 0 ; i < nsig ; i++)
__sigaddset(&mask, sigs[i]);
#if defined(__i386__)
ret = INLINE_SYSCALL(sigprocmask, 3, how, &mask, NULL)
#else
ret = INLINE_SYSCALL(rt_sigprocmask, 4, how, &mask, NULL,
sizeof(sigset_t));
#endif
if (IS_ERR(ret))
return -ERRNO(ret);
return 0;
}
int block_async_signals (bool block)
{
return block_signals(block, async_signals, nasync_signals);
}
static int get_event_num (int signum)
{
switch(signum) {
case SIGFPE: return PAL_EVENT_ARITHMETIC_ERROR;
case SIGSEGV: case SIGBUS: return PAL_EVENT_MEMFAULT;
case SIGILL: return PAL_EVENT_ILLEGAL;
case SIGTERM: return PAL_EVENT_QUIT;
case SIGINT: return PAL_EVENT_SUSPEND;
case SIGCONT: return PAL_EVENT_RESUME;
default: return -1;
}
}
void sgx_entry_return (void);
static void _DkTerminateSighandler (int signum, siginfo_t * info,
struct ucontext * uc)
{
__UNUSED(info);
unsigned long rip = uc->uc_mcontext.gregs[REG_RIP];
if (rip != (unsigned long) async_exit_pointer) {
uc->uc_mcontext.gregs[REG_RIP] = (uint64_t) sgx_entry_return;
uc->uc_mcontext.gregs[REG_RDI] = -EINTR;
uc->uc_mcontext.gregs[REG_RSI] = get_event_num(signum);
} else {
sgx_raise(get_event_num(signum));
}
}
static void _DkResumeSighandler (int signum, siginfo_t * info,
struct ucontext * uc)
{
__UNUSED(info);
unsigned long rip = uc->uc_mcontext.gregs[REG_RIP];
if (rip != (unsigned long) async_exit_pointer) {
switch (signum) {
case SIGSEGV:
SGX_DBG(DBG_E, "Segmentation Fault in Untrusted Code (RIP = %08lx)\n", rip);
break;
case SIGILL:
SGX_DBG(DBG_E, "Illegal Instruction in Untrusted Code (RIP = %08lx)\n", rip);
break;
case SIGFPE:
SGX_DBG(DBG_E, "Arithmetic Exception in Untrusted Code (RIP = %08lx)\n", rip);
break;
case SIGBUS:
SGX_DBG(DBG_E, "Memory Mapping Exception in Untrusted Code (RIP = %08lx)\n", rip);
break;
}
INLINE_SYSCALL(exit, 1, 1);
}
int event = get_event_num(signum);
sgx_raise(event);
}
int sgx_signal_setup (void)
{
int ret, sig[4];
sig[0] = SIGTERM;
sig[1] = SIGINT;
sig[2] = SIGCONT;
if ((ret = set_sighandler(sig, 3, &_DkTerminateSighandler)) < 0)
goto err;
sig[0] = SIGSEGV;
sig[1] = SIGILL;
sig[2] = SIGFPE;
sig[3] = SIGBUS;
if ((ret = set_sighandler(sig, 4, &_DkResumeSighandler)) < 0)
goto err;
return 0;
err:
return ret;
}