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- /* 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 <http://www.gnu.org/licenses/>. */
- /*
- * 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 <atomic.h>
- #include <sigset.h>
- #include <linux/signal.h>
- #include <ucontext.h>
- #include <asm/errno.h>
- #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;
- }
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