/* * Copyright (C) 2011-2017 Intel Corporation. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * Neither the name of Intel Corporation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ #include "arch.h" #include "sgx_error.h" #include "tcs.h" #include "se_trace.h" #include "xsave.h" #include "rts.h" #include "enclave.h" #include #include #include #include typedef struct _ecall_param_t { tcs_t *tcs; long fn; //long because we need register bandwith align on stack, refer to enter_enclave.h; void *ocall_table; void *ms; CTrustThread *trust_thread; } ecall_param_t; #ifdef __x86_64__ #define REG_XIP REG_RIP #define REG_XAX REG_RAX #define REG_XBX REG_RBX #define REG_XSI REG_RSI #define REG_XBP REG_RBP /* * refer to enter_enclave.h * stack high address <------------- * |rip|rbp|rbx|r10|r13|r14|r15|r8|rcx|rdx|rsi|rdi| * ^ ^ * | <-rbp | <-param4 */ #define ECALL_PARAM (reinterpret_cast(context->uc_mcontext.gregs[REG_RBP] - 10 * 8)) #else #define REG_XIP REG_EIP #define REG_XAX REG_EAX #define REG_XBX REG_EBX #define REG_XSI REG_ESI #define REG_XBP REG_EBP /* * refer to enter_enclave.h * stack high address <------------- * |param4|param3|param2|param2|param0|eip|ebp| * ^ * | <-ebp */ #define ECALL_PARAM (reinterpret_cast(context->uc_mcontext.gregs[REG_EBP] + 2 * 4)) #endif extern "C" void *get_aep(); extern "C" void *get_eenterp(); extern "C" void *get_eretp(); static struct sigaction g_old_sigact[_NSIG]; void reg_sig_handler(); void sig_handler(int signum, siginfo_t* siginfo, void *priv) { SE_TRACE(SE_TRACE_DEBUG, "signal handler is triggered\n"); ucontext_t* context = reinterpret_cast(priv); unsigned int *xip = reinterpret_cast(context->uc_mcontext.gregs[REG_XIP]); size_t xax = context->uc_mcontext.gregs[REG_XAX]; #ifndef NDEBUG /* `xbx' is only used in assertions. */ size_t xbx = context->uc_mcontext.gregs[REG_XBX]; #endif ecall_param_t *param = ECALL_PARAM; //the case of exception on ERESUME or within enclave. //We can't distinguish ERESUME exception from exception within enclave. We assume it is the exception within enclave. //If it is ERESUME exception, it will raise another exception in ecall and ecall will return error. if(xip == get_aep() && SE_ERESUME == xax) { assert(ENCLU == (*xip & 0xffffff)); //suppose the exception is within enclave. SE_TRACE(SE_TRACE_NOTICE, "exception on ERESUME\n"); //The ecall looks recursively, but it will not cause infinite call. //If exception is raised in trts again and again, the SSA will overflow, and finally it is EENTER exception. assert(reinterpret_cast(xbx) == param->tcs); CEnclave *enclave = param->trust_thread->get_enclave(); unsigned int ret = enclave->ecall(ECMD_EXCEPT, param->ocall_table, NULL); if(SGX_SUCCESS == ret) { //ERESUME execute return; } //If the exception is caused by enclave lost or internal stack overrun, then return the error code to ecall caller elegantly. else if(SGX_ERROR_ENCLAVE_LOST == ret || SGX_ERROR_STACK_OVERRUN == ret) { //enter_enlcave function will return with ret which is from tRTS; context->uc_mcontext.gregs[REG_XIP] = reinterpret_cast(get_eretp()); context->uc_mcontext.gregs[REG_XSI] = ret; return; } //If we can't fix the exception within enclave, then give the handle to other signal hanlder. //Call the previous signal handler. The default signal handler should terminate the application. enclave->rdunlock(); CEnclavePool::instance()->unref_enclave(enclave); } //the case of exception on EENTER instruction. else if(xip == get_eenterp() && SE_EENTER == xax) { assert(reinterpret_cast(xbx) == param->tcs); assert(ENCLU == (*xip & 0xffffff)); SE_TRACE(SE_TRACE_NOTICE, "exception on EENTER\n"); //enter_enlcave function will return with SE_ERROR_ENCLAVE_LOST context->uc_mcontext.gregs[REG_XIP] = reinterpret_cast(get_eretp()); context->uc_mcontext.gregs[REG_XSI] = SGX_ERROR_ENCLAVE_LOST; return; } SE_TRACE(SE_TRACE_DEBUG, "NOT enclave signal\n"); //it is not SE exception. if the old signal handler is default signal handler, we reset signal handler. //raise the signal again, and the default signal handler will be called. if(SIG_DFL == g_old_sigact[signum].sa_handler) { signal(signum, SIG_DFL); raise(signum); } //if there is old signal handler, we need transfer the signal to the old signal handler; else { if(!(g_old_sigact[signum].sa_flags & SA_NODEFER)) sigaddset(&g_old_sigact[signum].sa_mask, signum); sigset_t cur_set; pthread_sigmask(SIG_SETMASK, &g_old_sigact[signum].sa_mask, &cur_set); if(g_old_sigact[signum].sa_flags & SA_SIGINFO) { g_old_sigact[signum].sa_sigaction(signum, siginfo, priv); } else { g_old_sigact[signum].sa_handler(signum); } pthread_sigmask(SIG_SETMASK, &cur_set, NULL); //If the g_old_sigact set SA_RESETHAND, it will break the chain which means //g_old_sigact->next_old_sigact will not be called. Our signal handler does not //responsable for that. We just follow what os do on SA_RESETHAND. if(g_old_sigact[signum].sa_flags & SA_RESETHAND) g_old_sigact[signum].sa_handler = SIG_DFL; } } void reg_sig_handler() { int ret = 0; struct sigaction sig_act; SE_TRACE(SE_TRACE_DEBUG, "signal handler is registered\n"); memset(&sig_act, 0, sizeof(sig_act)); sig_act.sa_sigaction = sig_handler; sig_act.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART; sigemptyset(&sig_act.sa_mask); if(sigprocmask(SIG_SETMASK, NULL, &sig_act.sa_mask)) { SE_TRACE(SE_TRACE_WARNING, "%s\n", strerror(errno)); } else { sigdelset(&sig_act.sa_mask, SIGSEGV); sigdelset(&sig_act.sa_mask, SIGFPE); sigdelset(&sig_act.sa_mask, SIGILL); sigdelset(&sig_act.sa_mask, SIGBUS); sigdelset(&sig_act.sa_mask, SIGTRAP); } ret = sigaction(SIGSEGV, &sig_act, &g_old_sigact[SIGSEGV]); if (0 != ret) abort(); ret = sigaction(SIGFPE, &sig_act, &g_old_sigact[SIGFPE]); if (0 != ret) abort(); ret = sigaction(SIGILL, &sig_act, &g_old_sigact[SIGILL]); if (0 != ret) abort(); ret = sigaction(SIGBUS, &sig_act, &g_old_sigact[SIGBUS]); if (0 != ret) abort(); ret = sigaction(SIGTRAP, &sig_act, &g_old_sigact[SIGTRAP]); if (0 != ret) abort(); } //trust_thread is saved at stack for ocall. #define enter_enclave __morestack extern "C" int enter_enclave(const tcs_t *tcs, const long fn, const void *ocall_table, const void *ms, CTrustThread *trust_thread); int do_ecall(const int fn, const void *ocall_table, const void *ms, CTrustThread *trust_thread) { int status = SGX_ERROR_UNEXPECTED; #ifdef SE_SIM CEnclave* enclave = trust_thread->get_enclave(); //check if it is current pid, it is to simulate fork() scenario on HW sgx_enclave_id_t eid = enclave->get_enclave_id(); if((pid_t)(eid >> 32) != getpid()) return SGX_ERROR_ENCLAVE_LOST; #endif tcs_t *tcs = trust_thread->get_tcs(); //seh_handler.cpp have the same code to save and restore pf register. //put the save register code here, because we want remind maintainer we should do it near EENTER uint8_t buffer[FXSAVE_SIZE]; save_and_clean_xfeature_regs(buffer); status = enter_enclave(tcs, fn, ocall_table, ms, trust_thread); restore_xfeature_regs(buffer); return status; } int do_ocall(const bridge_fn_t bridge, void *ms) { int error = SGX_ERROR_UNEXPECTED; error = bridge(ms); save_and_clean_xfeature_regs(NULL); return error; }