samples: code style for sample_x86_32_gdt_and_seg_regs.c
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Nguyen Anh Quynh
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cf793122be
commit
e44f8f2981
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@ -27,40 +27,40 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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#include <unistd.h>
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struct SegmentDescriptor {
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union {
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struct {
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union {
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struct {
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# if __BYTE_ORDER == __LITTLE_ENDIAN
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unsigned short limit0;
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unsigned short base0;
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unsigned char base1;
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unsigned int type:4;
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unsigned int system:1; /* S flag */
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unsigned int dpl:2;
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unsigned int present:1; /* P flag */
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unsigned int limit1:4;
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unsigned int avail:1;
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unsigned int is_64_code:1; /* L flag */
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unsigned int db:1; /* DB flag */
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unsigned int granularity:1; /* G flag */
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unsigned char base2;
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unsigned short limit0;
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unsigned short base0;
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unsigned char base1;
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unsigned int type:4;
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unsigned int system:1; /* S flag */
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unsigned int dpl:2;
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unsigned int present:1; /* P flag */
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unsigned int limit1:4;
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unsigned int avail:1;
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unsigned int is_64_code:1; /* L flag */
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unsigned int db:1; /* DB flag */
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unsigned int granularity:1; /* G flag */
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unsigned char base2;
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# else
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unsigned char base2;
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unsigned int granularity:1; /* G flag */
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unsigned int db:1; /* DB flag */
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unsigned int is_64_code:1; /* L flag */
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unsigned int avail:1;
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unsigned int limit1:4;
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unsigned int present:1; /* P flag */
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unsigned int dpl:2;
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unsigned int system:1; /* S flag */
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unsigned int type:4;
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unsigned char base1;
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unsigned short base0;
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unsigned short limit0;
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unsigned char base2;
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unsigned int granularity:1; /* G flag */
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unsigned int db:1; /* DB flag */
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unsigned int is_64_code:1; /* L flag */
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unsigned int avail:1;
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unsigned int limit1:4;
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unsigned int present:1; /* P flag */
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unsigned int dpl:2;
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unsigned int system:1; /* S flag */
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unsigned int type:4;
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unsigned char base1;
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unsigned short base0;
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unsigned short limit0;
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# endif
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};
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uint64_t desc;
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};
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};
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uint64_t desc;
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};
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};
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#define SEGBASE(d) ((uint32_t)((((d).desc >> 16) & 0xffffff) | (((d).desc >> 32) & 0xff000000)))
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@ -103,42 +103,47 @@ do { \
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/******************************************************************************/
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void hook_mem(uc_engine *uc, uc_mem_type type, uint64_t address, int size, int64_t value, void *user_data) {
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switch(type) {
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case UC_MEM_WRITE:
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printf("mem write at 0x%"PRIx64 ", size = %u, value = 0x%"PRIx64 "\n", address, size, value);
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break;
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default: break;
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}
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static void hook_mem(uc_engine *uc, uc_mem_type type, uint64_t address, int size, int64_t value, void *user_data)
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{
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switch(type) {
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case UC_MEM_WRITE:
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printf("mem write at 0x%"PRIx64 ", size = %u, value = 0x%"PRIx64 "\n", address, size, value);
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break;
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default: break;
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}
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}
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void hook_code(uc_engine *uc, uint64_t address, uint32_t size, void *user_data) {
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static void hook_code(uc_engine *uc, uint64_t address, uint32_t size, void *user_data)
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{
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printf("Executing at 0x%"PRIx64 ", ilen = 0x%x\n", address, size);
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}
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//VERY basic descriptor init function, sets many fields to user space sane defaults
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void init_descriptor(struct SegmentDescriptor *desc, uint32_t base, uint32_t limit, uint8_t is_code) {
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desc->desc = 0; //clear the descriptor
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desc->base0 = base & 0xffff;
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desc->base1 = (base >> 16) & 0xff;
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desc->base2 = base >> 24;
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if (limit > 0xfffff) {
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//need Giant granularity
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limit >>= 12;
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desc->granularity = 1;
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}
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desc->limit0 = limit & 0xffff;
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desc->limit1 = limit >> 16;
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//some sane defaults
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desc->dpl = 3;
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desc->present = 1;
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desc->db = 1; //32 bit
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desc->type = is_code ? 0xb : 3;
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desc->system = 1; //code or data
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static void init_descriptor(struct SegmentDescriptor *desc, uint32_t base, uint32_t limit, uint8_t is_code)
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{
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desc->desc = 0; //clear the descriptor
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desc->base0 = base & 0xffff;
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desc->base1 = (base >> 16) & 0xff;
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desc->base2 = base >> 24;
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if (limit > 0xfffff) {
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//need Giant granularity
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limit >>= 12;
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desc->granularity = 1;
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}
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desc->limit0 = limit & 0xffff;
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desc->limit1 = limit >> 16;
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//some sane defaults
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desc->dpl = 3;
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desc->present = 1;
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desc->db = 1; //32 bit
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desc->type = is_code ? 0xb : 3;
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desc->system = 1; //code or data
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}
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void hex_dump(unsigned char *ptr, unsigned int len) {
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/*
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static void hex_dump(unsigned char *ptr, unsigned int len)
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{
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int i;
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for (i = 0; i < len; i++) {
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if (i != 0 && (i & 0xf) == 0) {
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@ -148,23 +153,25 @@ void hex_dump(unsigned char *ptr, unsigned int len) {
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}
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fprintf(stderr, "\n");
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}
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*/
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static void gdt_demo() {
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static void gdt_demo()
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{
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uc_engine *uc;
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uc_hook hook1, hook2;
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uc_err err;
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uint8_t buf[128];
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uc_x86_mmr gdtr;
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/*
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bits 32
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/*
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bits 32
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push dword 0x01234567
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push dword 0x89abcdef
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push dword 0x01234567
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push dword 0x89abcdef
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mov dword [fs:0], 0x01234567
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mov dword [fs:4], 0x89abcdef
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*/
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mov dword [fs:0], 0x01234567
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mov dword [fs:4], 0x89abcdef
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*/
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const uint8_t code[] = "\x68\x67\x45\x23\x01\x68\xef\xcd\xab\x89\x64\xc7\x05\x00\x00\x00\x00\x67\x45\x23\x01\x64\xc7\x05\x04\x00\x00\x00\xef\xcd\xab\x89";
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const uint64_t code_address = 0x1000000;
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@ -183,17 +190,17 @@ mov dword [fs:4], 0x89abcdef
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gdtr.base = gdt_address;
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gdtr.limit = 31 * sizeof(struct SegmentDescriptor) - 1;
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init_descriptor(&gdt[14], 0, 0xfffff000, 1); //code segment
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init_descriptor(&gdt[15], 0, 0xfffff000, 0); //data segment
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init_descriptor(&gdt[16], 0x7efdd000, 0xfff, 0); //one page data segment simulate fs
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init_descriptor(&gdt[17], 0, 0xfffff000, 0); //ring 0 data
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gdt[17].dpl = 0; //set descriptor privilege level
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/*
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fprintf(stderr, "GDT: \n");
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hex_dump((unsigned char*)gdt, 31 * sizeof(struct SegmentDescriptor));
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*/
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/*
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fprintf(stderr, "GDT: \n");
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hex_dump((unsigned char*)gdt, 31 * sizeof(struct SegmentDescriptor));
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*/
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// Initialize emulator in X86-32bit mode
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err = uc_open(UC_ARCH_X86, UC_MODE_32, &uc);
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@ -257,10 +264,10 @@ mov dword [fs:4], 0x89abcdef
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// read from memory
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err = uc_mem_read(uc, r_esp - 8, buf, 8);
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uc_assert_success(err);
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int i;
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for (i = 0; i < 8; i++) {
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fprintf(stderr, "%02hhx", buf[i]);
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fprintf(stderr, "%02hhx", buf[i]);
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}
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fprintf(stderr, "\n");
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@ -273,15 +280,15 @@ mov dword [fs:4], 0x89abcdef
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assert(memcmp(buf, "\x67\x45\x23\x01\xef\xcd\xab\x89", 8) == 0);
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uc_close(uc);
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}
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/******************************************************************************/
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int main(int argc, char **argv) {
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gdt_demo();
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fprintf(stderr, "success\n");
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return 0;
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int main(int argc, char **argv)
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{
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gdt_demo();
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fprintf(stderr, "success\n");
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return 0;
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}
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