SGX enclave GPRSGX region https://github.com/intel/linux-sgx/issues/519

App.cpp

/*
 * 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 <stdio.h>
#include <string.h>
#include <assert.h>

# include <unistd.h>
# include <pwd.h>
# define MAX_PATH FILENAME_MAX

#include "sgx_urts.h"
#include "App.h"
#include "Enclave_u.h"

/* Global EID shared by multiple threads */
sgx_enclave_id_t global_eid = 0;

typedef struct _sgx_errlist_t {
    sgx_status_t err;
    const char *msg;
    const char *sug; /* Suggestion */
} sgx_errlist_t;

/* Error code returned by sgx_create_enclave */
static sgx_errlist_t sgx_errlist[] = {
    {
        SGX_ERROR_UNEXPECTED,
        "Unexpected error occurred.",
        NULL
    },
    {
        SGX_ERROR_INVALID_PARAMETER,
        "Invalid parameter.",
        NULL
    },
    {
        SGX_ERROR_OUT_OF_MEMORY,
        "Out of memory.",
        NULL
    },
    {
        SGX_ERROR_ENCLAVE_LOST,
        "Power transition occurred.",
        "Please refer to the sample \"PowerTransition\" for details."
    },
    {
        SGX_ERROR_INVALID_ENCLAVE,
        "Invalid enclave image.",
        NULL
    },
    {
        SGX_ERROR_INVALID_ENCLAVE_ID,
        "Invalid enclave identification.",
        NULL
    },
    {
        SGX_ERROR_INVALID_SIGNATURE,
        "Invalid enclave signature.",
        NULL
    },
    {
        SGX_ERROR_OUT_OF_EPC,
        "Out of EPC memory.",
        NULL
    },
    {
        SGX_ERROR_NO_DEVICE,
        "Invalid SGX device.",
        "Please make sure SGX module is enabled in the BIOS, and install SGX driver afterwards."
    },
    {
        SGX_ERROR_MEMORY_MAP_CONFLICT,
        "Memory map conflicted.",
        NULL
    },
    {
        SGX_ERROR_INVALID_METADATA,
        "Invalid enclave metadata.",
        NULL
    },
    {
        SGX_ERROR_DEVICE_BUSY,
        "SGX device was busy.",
        NULL
    },
    {
        SGX_ERROR_INVALID_VERSION,
        "Enclave version was invalid.",
        NULL
    },
    {
        SGX_ERROR_INVALID_ATTRIBUTE,
        "Enclave was not authorized.",
        NULL
    },
    {
        SGX_ERROR_ENCLAVE_FILE_ACCESS,
        "Can't open enclave file.",
        NULL
    },
};

/* Check error conditions for loading enclave */
void print_error_message(sgx_status_t ret)
{
    size_t idx = 0;
    size_t ttl = sizeof sgx_errlist/sizeof sgx_errlist[0];

    for (idx = 0; idx < ttl; idx++) {
        if(ret == sgx_errlist[idx].err) {
            if(NULL != sgx_errlist[idx].sug)
                printf("Info: %s\n", sgx_errlist[idx].sug);
            printf("Error: %s\n", sgx_errlist[idx].msg);
            break;
        }
    }
    
    if (idx == ttl)
    	printf("Error code is 0x%X. Please refer to the \"Intel SGX SDK Developer Reference\" for more details.\n", ret);
}

/* Initialize the enclave:
 *   Step 1: try to retrieve the launch token saved by last transaction
 *   Step 2: call sgx_create_enclave to initialize an enclave instance
 *   Step 3: save the launch token if it is updated
 */
int initialize_enclave(void)
{
    char token_path[MAX_PATH] = {'\0'};
    sgx_launch_token_t token = {0};
    sgx_status_t ret = SGX_ERROR_UNEXPECTED;
    int updated = 0;
    
    /* Step 1: try to retrieve the launch token saved by last transaction 
     *         if there is no token, then create a new one.
     */
    /* try to get the token saved in $HOME */
    const char *home_dir = getpwuid(getuid())->pw_dir;
    
    if (home_dir != NULL && 
        (strlen(home_dir)+strlen("/")+sizeof(TOKEN_FILENAME)+1) <= MAX_PATH) {
        /* compose the token path */
        strncpy(token_path, home_dir, strlen(home_dir));
        strncat(token_path, "/", strlen("/"));
        strncat(token_path, TOKEN_FILENAME, sizeof(TOKEN_FILENAME)+1);
    } else {
        /* if token path is too long or $HOME is NULL */
        strncpy(token_path, TOKEN_FILENAME, sizeof(TOKEN_FILENAME));
    }

    FILE *fp = fopen(token_path, "rb");
    if (fp == NULL && (fp = fopen(token_path, "wb")) == NULL) {
        printf("Warning: Failed to create/open the launch token file \"%s\".\n", token_path);
    }

    if (fp != NULL) {
        /* read the token from saved file */
        size_t read_num = fread(token, 1, sizeof(sgx_launch_token_t), fp);
        if (read_num != 0 && read_num != sizeof(sgx_launch_token_t)) {
            /* if token is invalid, clear the buffer */
            memset(&token, 0x0, sizeof(sgx_launch_token_t));
            printf("Warning: Invalid launch token read from \"%s\".\n", token_path);
        }
    }
    /* Step 2: call sgx_create_enclave to initialize an enclave instance */
    /* Debug Support: set 2nd parameter to 1 */
    ret = sgx_create_enclave(ENCLAVE_FILENAME, SGX_DEBUG_FLAG, &token, &updated, &global_eid, NULL);
    if (ret != SGX_SUCCESS) {
        print_error_message(ret);
        if (fp != NULL) fclose(fp);
        return -1;
    }

    /* Step 3: save the launch token if it is updated */
    if (updated == FALSE || fp == NULL) {
        /* if the token is not updated, or file handler is invalid, do not perform saving */
        if (fp != NULL) fclose(fp);
        return 0;
    }

    /* reopen the file with write capablity */
    fp = freopen(token_path, "wb", fp);
    if (fp == NULL) return 0;
    size_t write_num = fwrite(token, 1, sizeof(sgx_launch_token_t), fp);
    if (write_num != sizeof(sgx_launch_token_t))
        printf("Warning: Failed to save launch token to \"%s\".\n", token_path);
    fclose(fp);
    return 0;
}

/* OCall functions */
void ocall_print_string(const char *str)
{
    /* Proxy/Bridge will check the length and null-terminate 
     * the input string to prevent buffer overflow. 
     */
    printf("%s", str);
}


/* Application entry */
int SGX_CDECL main(int argc, char *argv[])
{
    (void)(argc);
    (void)(argv);

	register long long esp asm("esp");
	printf("esp = %lld\n" , esp);

    /* Initialize the enclave */
    if(initialize_enclave() < 0){
        printf("Enter a character before exit ...\n");
        getchar();
        return -1; 
    }
 
    printf_helloworld(global_eid, 0);
	
	printf("hello2222\n");

	printf_helloworld(global_eid, 1);

	//__asm( "mov register_URSP, %(gs)+0x20+0x90;" );

/*	int offset = 36;
	int gs;
	asm ("mov %%gs:(%1), %0" : "=r"(gs) : "r"(offset));

	printf("gs = %d\n", gs);
*/
    /* Destroy the enclave */
    sgx_destroy_enclave(global_eid);
    
    printf("already_destroyed_enclave\n");

    return 0;
}

Enclave.cpp

/*
 * 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 <stdarg.h>
#include <stdio.h>      /* vsnprintf */

#include "Enclave.h"
#include "Enclave_t.h"  /* print_string */

#include "thread_data.h"
#include "arch.h"

//extern "C" void* get_thread_data();

/* 
 * printf: 
 *   Invokes OCALL to display the enclave buffer to the terminal.
 */

void printf(const char *fmt, ...)
{
    char buf[BUFSIZ] = {'\0'};
    va_list ap;
    va_start(ap, fmt);
    vsnprintf(buf, BUFSIZ, fmt, ap);
    va_end(ap);
    ocall_print_string(buf);
}

void printf_helloworld(int flag)
{
    printf("xxxHello World\n");

	// https://web.cse.ohio-state.edu/~lin.3021/file/RAID17.pdf#page=10
	// %gs:0x20 always points to the GPRSGX region

	// Layout of GPRSGX Portion of the State Save Area :
	// https://www.intel.com/content/dam/www/public/emea/xe/en/documents/manuals/64-ia-32-architectures-software-developer-vol-3d-part-4-manual.pdf#page=15

    uintptr_t offset = 176; // 32 bytes + 144 bytes = 0x20 + 0x90 = 0xB0
    long long ursp;

	//asm ("mov %%gs:%1, %0" : "=r"(ursp) : "m"(*(char *)offset)); // 2338810765860929536
    //asm ("mov %%gs:(%1), %0" : "=r"(ursp) : "r"(offset)); // -4290487885628440576
	//asm ("mov %%gs:0xB0, %0" : "=r"(ursp)); // 0
	asm ("mov %%gs:0x20 , %0" : "=r"(ursp)); // 140306321915720

	printf("divisor = %d\n", divisor);

	if(flag == 0) divisor = 0;

//	else divisor = 1;

	dividend = 10;

	printf("Before divison operation\n");

	printf("divisor = %d\n", divisor);
	printf("dividend = %d\n", dividend);

	try {
		if(divisor == 0) throw "Division by zero condition!\n";
		
		else 
		{
			quotient = dividend / divisor;
			printf("inside the else\n");
			printf("ursp = %lld\n", ursp);
			printf("quotient = %d\n", quotient);
		}
	} 
	catch (const char* msg) {

		printf("Inside catch()\n");			

		printf("ursp = %lld\n", ursp);

		printf("divisor = %d\n", divisor);

		divisor = 1; // test the value persistence of enclave variables after enclave re-entry
		
		printf(msg);

		printf("After divison operation\n");
		printf("divisor = %d\n", divisor);
	}

	printf("Outside of throw-catch exception block\n");

	printf("ursp = %lld\n", ursp);

	printf("divisor = %d\n", divisor);


    // 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);

	// https://github.com/intel/linux-sgx/blob/master/common/inc/internal/arch.h#L129-L155
    size_t rax_addr = ssa_gpr->REG(ax); // RAX
	size_t ursp_addr = ssa_gpr->REG(sp_u); // URSP

	// rax_addr and ursp_addr do not match the value of %%gs:0x20 and host's ESP respectively
	printf("using API call, start of GPRSGX region = %lld\n", rax_addr); 
	printf("using API call, URSP of GPRSGX region = %lld\n", ursp_addr);


	//printf("using API call, start of GPRSGX region = %lld\n", *(long long*) (p+0x20));
}