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trts.cpp
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trts.cpp
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/*
* Copyright (C) 2011-2018 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 "sgx_trts.h"
#include "sgx_edger8r.h"
#include "trts_inst.h"
#include <stdlib.h>
#include <string.h>
#include "util.h"
#include "thread_data.h"
#include "global_data.h"
#include "trts_internal.h"
#include "internal/rts.h"
#ifdef SE_SIM
#include "t_instructions.h" /* for `g_global_data_sim' */
#include "sgx_spinlock.h"
#include "se_cpu_feature.h"
#endif
#ifndef SE_SIM
#include "se_cdefs.h"
// add a version to trts
SGX_ACCESS_VERSION(trts, 1);
#endif
// sgx_is_within_enclave()
// Parameters:
// addr - the start address of the buffer
// size - the size of the buffer
// Return Value:
// 1 - the buffer is strictly within the enclave
// 0 - the whole buffer or part of the buffer is not within the enclave,
// or the buffer is wrap around
//
int sgx_is_within_enclave(const void *addr, size_t size)
{
size_t start = reinterpret_cast<size_t>(addr);
size_t end = 0;
size_t enclave_start = (size_t)&__ImageBase;
size_t enclave_end = enclave_start + g_global_data.enclave_size - 1;
// g_global_data.enclave_end = enclave_base + enclave_size - 1;
// so the enclave range is [enclave_start, enclave_end] inclusively
if(size > 0)
{
end = start + size - 1;
}
else
{
end = start;
}
if( (start <= end) && (start >= enclave_start) && (end <= enclave_end) )
{
return 1;
}
return 0;
}
// sgx_is_outside_enclave()
// Parameters:
// addr - the start address of the buffer
// size - the size of the buffer
// Return Value:
// 1 - the buffer is strictly outside the enclave
// 0 - the whole buffer or part of the buffer is not outside the enclave,
// or the buffer is wrap around
//
int sgx_is_outside_enclave(const void *addr, size_t size)
{
size_t start = reinterpret_cast<size_t>(addr);
size_t end = 0;
size_t enclave_start = (size_t)&__ImageBase;
size_t enclave_end = enclave_start + g_global_data.enclave_size - 1;
// g_global_data.enclave_end = enclave_base + enclave_size - 1;
// so the enclave range is [enclave_start, enclave_end] inclusively
if(size > 0)
{
end = start + size - 1;
}
else
{
end = start;
}
if( (start <= end) && ((end < enclave_start) || (start > enclave_end)) )
{
return 1;
}
return 0;
}
// sgx_ocalloc()
// Parameters:
// size - bytes to allocate on the outside stack
// Return Value:
// the pointer to the allocated space on the outside stack
// NULL - fail to allocate
//
// sgx_ocalloc allocates memory on the outside stack. It is only used for OCALL, and will be auto freed when ECALL returns.
// To achieve this, the outside stack pointer in SSA is updated when the stack memory is allocated,
// but the outside stack pointer saved in the ECALL stack frame is not changed accordingly.
// When doing an OCALL, the stack pointer is set as the value in SSA and EEXIT.
// When ECALL or exception handling returns, the stack pointer is set as the value in the ECALL stack frame and then EEXIT,
// so the outside stack is automatically unwind.
// In addition, sgx_ocalloc needs perform outside stack probe to make sure it is not allocating beyond the end of the stack.
#define OC_ROUND 16
void * sgx_ocalloc(size_t size)
{
// read the outside stack address from current SSA
thread_data_t *thread_data = get_thread_data();
ssa_gpr_t *ssa_gpr = reinterpret_cast<ssa_gpr_t *>(thread_data->first_ssa_gpr);
size_t addr = ssa_gpr->REG(sp_u);
// check u_rsp points to the untrusted address.
// if the check fails, it should be hacked. call abort directly
if(!sgx_is_outside_enclave(reinterpret_cast<void *>(addr), sizeof(size_t)))
{
abort();
}
// size is too large to allocate. call abort() directly.
if(addr < size)
{
abort();
}
// calculate the start address for the allocated memory
addr -= size;
addr &= ~(static_cast<size_t>(OC_ROUND - 1)); // for stack alignment
// the allocated memory has overlap with enclave, abort the enclave
if(!sgx_is_outside_enclave(reinterpret_cast<void *>(addr), size))
{
abort();
}
// probe the outside stack to ensure that we do not skip over the stack3 guard page
// we need to probe all the pages including the first page and the last page
// the first page need to be probed in case uRTS didnot touch that page before EENTER enclave
// the last page need to be probed in case the enclave didnot touch that page before another OCALLOC
size_t first_page = TRIM_TO_PAGE(ssa_gpr->REG(sp_u) - 1);
size_t last_page = TRIM_TO_PAGE(addr);
// To avoid the dead-loop in the following for(...) loop.
// Attacker might fake a stack address that is within address 0x4095.
if (last_page == 0)
{
abort();
}
// the compiler may optimize the following code to probe the pages in any order
// while we only expect the probe order should be from higher addr to lower addr
// so use volatile to avoid optimization by the compiler
for(volatile size_t page = first_page; page >= last_page; page -= SE_PAGE_SIZE)
{
// OS may refuse to commit a physical page if the page fault address is smaller than RSP
// So update the outside stack address before probe the page
ssa_gpr->REG(sp_u) = page;
*reinterpret_cast<uint8_t *>(page) = 0;
}
// update the outside stack address in the SSA to the allocated address
ssa_gpr->REG(sp_u) = addr;
return reinterpret_cast<void *>(addr);
}
weak_alias(sgx_ocalloc, sgx_ocalloc_switchless);
// sgx_ocfree()
// Parameters:
// N/A
// Return Value:
// N/A
// sgx_ocfree restores the original outside stack pointer in the SSA.
// Do not call this function if you still need the buffer allocated by sgx_ocalloc within the ECALL.
void sgx_ocfree()
{
// ECALL stack frame
// last_sp -> | |
// -------------
// | ret_addr |
// | xbp_u |
// | xsp_u |
thread_data_t *thread_data = get_thread_data();
ssa_gpr_t *ssa_gpr = reinterpret_cast<ssa_gpr_t *>(thread_data->first_ssa_gpr);
uintptr_t *addr = reinterpret_cast<uintptr_t *>(thread_data->last_sp);
uintptr_t usp = *(addr - 3);
if(!sgx_is_outside_enclave(reinterpret_cast<void *>(usp), sizeof(uintptr_t)))
{
abort();
}
ssa_gpr->REG(sp_u) = usp;
}
weak_alias(sgx_ocfree, sgx_ocfree_switchless);
#ifdef SE_SIM
static sgx_spinlock_t g_seed_lock = SGX_SPINLOCK_INITIALIZER;
static uint32_t get_rand_lcg()
{
sgx_spin_lock(&g_seed_lock);
uint64_t& seed = g_global_data_sim.seed;
seed = (uint64_t)(6364136223846793005ULL * seed + 1);
uint32_t n = (uint32_t)(seed >> 32);
sgx_spin_unlock(&g_seed_lock);
return n;
}
#endif
static sgx_status_t __do_get_rand32(uint32_t* rand_num)
{
#ifndef SE_SIM
/* We expect the CPU has RDRAND support for HW mode. Otherwise, an exception will be thrown
* do_rdrand() will try to call RDRAND for 10 times
*/
if(0 == do_rdrand(rand_num))
return SGX_ERROR_UNEXPECTED;
#else
/* For simulation mode, if the CPU supports RDRAND, use RDRAND. Otherwise, use LCG*/
if(TEST_CPU_HAS_RDRAND)
{
if(0 == do_rdrand(rand_num))
return SGX_ERROR_UNEXPECTED;
}
else
{
/* use LCG in simulation mode */
*rand_num = get_rand_lcg();
}
#endif
return SGX_SUCCESS;
}
sgx_status_t sgx_read_rand(unsigned char *rand, size_t length_in_bytes)
{
// check parameters
//
// rand can be within or outside the enclave
if(!rand || !length_in_bytes)
{
return SGX_ERROR_INVALID_PARAMETER;
}
if(!sgx_is_within_enclave(rand, length_in_bytes) && !sgx_is_outside_enclave(rand, length_in_bytes))
{
return SGX_ERROR_INVALID_PARAMETER;
}
// loop to rdrand
uint32_t rand_num = 0;
while(length_in_bytes > 0)
{
sgx_status_t status = __do_get_rand32(&rand_num);
if(status != SGX_SUCCESS)
{
return status;
}
size_t size = (length_in_bytes < sizeof(rand_num)) ? length_in_bytes : sizeof(rand_num);
memcpy(rand, &rand_num, size);
rand += size;
length_in_bytes -= size;
}
memset_s(&rand_num, sizeof(rand_num), 0, sizeof(rand_num));
return SGX_SUCCESS;
}
int sgx_is_enclave_crashed()
{
return get_enclave_state() == ENCLAVE_CRASHED;
}
extern uintptr_t __stack_chk_guard;
int check_static_stack_canary(void *tcs)
{
size_t *canary = TCS2CANARY(tcs);
if ( *canary != (size_t)__stack_chk_guard)
{
return -1;
}
return 0;
}
void random_stack_notify_gdb(void *addr, size_t size)
{
UNUSED(addr);
UNUSED(size);
}