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samples: code style for sample_x86_32_gdt_and_seg_regs.c

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This commit is contained in:
Nguyen Anh Quynh
2016-03-27 10:25:46 +08:00
parent cf793122be
commit e44f8f2981
1 changed files with 88 additions and 81 deletions
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169
samples/sample_x86_32_gdt_and_seg_regs.c
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@ -27,40 +27,40 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#include <unistd.h> #include <unistd.h>
struct SegmentDescriptor { struct SegmentDescriptor {
union { union {
struct { struct {
# if __BYTE_ORDER == __LITTLE_ENDIAN # if __BYTE_ORDER == __LITTLE_ENDIAN
unsigned short limit0; unsigned short limit0;
unsigned short base0; unsigned short base0;
unsigned char base1; unsigned char base1;
unsigned int type:4; unsigned int type:4;
unsigned int system:1; /* S flag */ unsigned int system:1; /* S flag */
unsigned int dpl:2; unsigned int dpl:2;
unsigned int present:1; /* P flag */ unsigned int present:1; /* P flag */
unsigned int limit1:4; unsigned int limit1:4;
unsigned int avail:1; unsigned int avail:1;
unsigned int is_64_code:1; /* L flag */ unsigned int is_64_code:1; /* L flag */
unsigned int db:1; /* DB flag */ unsigned int db:1; /* DB flag */
unsigned int granularity:1; /* G flag */ unsigned int granularity:1; /* G flag */
unsigned char base2; unsigned char base2;
# else # else
unsigned char base2; unsigned char base2;
unsigned int granularity:1; /* G flag */ unsigned int granularity:1; /* G flag */
unsigned int db:1; /* DB flag */ unsigned int db:1; /* DB flag */
unsigned int is_64_code:1; /* L flag */ unsigned int is_64_code:1; /* L flag */
unsigned int avail:1; unsigned int avail:1;
unsigned int limit1:4; unsigned int limit1:4;
unsigned int present:1; /* P flag */ unsigned int present:1; /* P flag */
unsigned int dpl:2; unsigned int dpl:2;
unsigned int system:1; /* S flag */ unsigned int system:1; /* S flag */
unsigned int type:4; unsigned int type:4;
unsigned char base1; unsigned char base1;
unsigned short base0; unsigned short base0;
unsigned short limit0; unsigned short limit0;
# endif # endif
}; };
uint64_t desc; uint64_t desc;
}; };
}; };
#define SEGBASE(d) ((uint32_t)((((d).desc >> 16) & 0xffffff) | (((d).desc >> 32) & 0xff000000))) #define SEGBASE(d) ((uint32_t)((((d).desc >> 16) & 0xffffff) | (((d).desc >> 32) & 0xff000000)))
@ -103,42 +103,47 @@ do { \
/******************************************************************************/ /******************************************************************************/
void hook_mem(uc_engine *uc, uc_mem_type type, uint64_t address, int size, int64_t value, void *user_data) { static void hook_mem(uc_engine *uc, uc_mem_type type, uint64_t address, int size, int64_t value, void *user_data)
switch(type) { {
case UC_MEM_WRITE: switch(type) {
printf("mem write at 0x%"PRIx64 ", size = %u, value = 0x%"PRIx64 "\n", address, size, value); case UC_MEM_WRITE:
break; printf("mem write at 0x%"PRIx64 ", size = %u, value = 0x%"PRIx64 "\n", address, size, value);
default: break; break;
} default: break;
}
} }
void hook_code(uc_engine *uc, uint64_t address, uint32_t size, void *user_data) { static void hook_code(uc_engine *uc, uint64_t address, uint32_t size, void *user_data)
{
printf("Executing at 0x%"PRIx64 ", ilen = 0x%x\n", address, size); printf("Executing at 0x%"PRIx64 ", ilen = 0x%x\n", address, size);
} }
//VERY basic descriptor init function, sets many fields to user space sane defaults //VERY basic descriptor init function, sets many fields to user space sane defaults
void init_descriptor(struct SegmentDescriptor *desc, uint32_t base, uint32_t limit, uint8_t is_code) { static void init_descriptor(struct SegmentDescriptor *desc, uint32_t base, uint32_t limit, uint8_t is_code)
desc->desc = 0; //clear the descriptor {
desc->base0 = base & 0xffff; desc->desc = 0; //clear the descriptor
desc->base1 = (base >> 16) & 0xff; desc->base0 = base & 0xffff;
desc->base2 = base >> 24; desc->base1 = (base >> 16) & 0xff;
if (limit > 0xfffff) { desc->base2 = base >> 24;
//need Giant granularity if (limit > 0xfffff) {
limit >>= 12; //need Giant granularity
desc->granularity = 1; limit >>= 12;
} desc->granularity = 1;
desc->limit0 = limit & 0xffff; }
desc->limit1 = limit >> 16; desc->limit0 = limit & 0xffff;
desc->limit1 = limit >> 16;
//some sane defaults
desc->dpl = 3; //some sane defaults
desc->present = 1; desc->dpl = 3;
desc->db = 1; //32 bit desc->present = 1;
desc->type = is_code ? 0xb : 3; desc->db = 1; //32 bit
desc->system = 1; //code or data desc->type = is_code ? 0xb : 3;
desc->system = 1; //code or data
} }
void hex_dump(unsigned char *ptr, unsigned int len) { /*
static void hex_dump(unsigned char *ptr, unsigned int len)
{
int i; int i;
for (i = 0; i < len; i++) { for (i = 0; i < len; i++) {
if (i != 0 && (i & 0xf) == 0) { if (i != 0 && (i & 0xf) == 0) {
@ -148,23 +153,25 @@ void hex_dump(unsigned char *ptr, unsigned int len) {
} }
fprintf(stderr, "\n"); fprintf(stderr, "\n");
} }
*/
static void gdt_demo() { static void gdt_demo()
{
uc_engine *uc; uc_engine *uc;
uc_hook hook1, hook2; uc_hook hook1, hook2;
uc_err err; uc_err err;
uint8_t buf[128]; uint8_t buf[128];
uc_x86_mmr gdtr; uc_x86_mmr gdtr;
/* /*
bits 32 bits 32
push dword 0x01234567 push dword 0x01234567
push dword 0x89abcdef push dword 0x89abcdef
mov dword [fs:0], 0x01234567 mov dword [fs:0], 0x01234567
mov dword [fs:4], 0x89abcdef mov dword [fs:4], 0x89abcdef
*/ */
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"; 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";
const uint64_t code_address = 0x1000000; const uint64_t code_address = 0x1000000;
@ -183,17 +190,17 @@ mov dword [fs:4], 0x89abcdef
gdtr.base = gdt_address; gdtr.base = gdt_address;
gdtr.limit = 31 * sizeof(struct SegmentDescriptor) - 1; gdtr.limit = 31 * sizeof(struct SegmentDescriptor) - 1;
init_descriptor(&gdt[14], 0, 0xfffff000, 1); //code segment init_descriptor(&gdt[14], 0, 0xfffff000, 1); //code segment
init_descriptor(&gdt[15], 0, 0xfffff000, 0); //data segment init_descriptor(&gdt[15], 0, 0xfffff000, 0); //data segment
init_descriptor(&gdt[16], 0x7efdd000, 0xfff, 0); //one page data segment simulate fs init_descriptor(&gdt[16], 0x7efdd000, 0xfff, 0); //one page data segment simulate fs
init_descriptor(&gdt[17], 0, 0xfffff000, 0); //ring 0 data init_descriptor(&gdt[17], 0, 0xfffff000, 0); //ring 0 data
gdt[17].dpl = 0; //set descriptor privilege level gdt[17].dpl = 0; //set descriptor privilege level
/* /*
fprintf(stderr, "GDT: \n"); fprintf(stderr, "GDT: \n");
hex_dump((unsigned char*)gdt, 31 * sizeof(struct SegmentDescriptor)); hex_dump((unsigned char*)gdt, 31 * sizeof(struct SegmentDescriptor));
*/ */
// Initialize emulator in X86-32bit mode // Initialize emulator in X86-32bit mode
err = uc_open(UC_ARCH_X86, UC_MODE_32, &uc); err = uc_open(UC_ARCH_X86, UC_MODE_32, &uc);
@ -257,10 +264,10 @@ mov dword [fs:4], 0x89abcdef
// read from memory // read from memory
err = uc_mem_read(uc, r_esp - 8, buf, 8); err = uc_mem_read(uc, r_esp - 8, buf, 8);
uc_assert_success(err); uc_assert_success(err);
int i; int i;
for (i = 0; i < 8; i++) { for (i = 0; i < 8; i++) {
fprintf(stderr, "%02hhx", buf[i]); fprintf(stderr, "%02hhx", buf[i]);
} }
fprintf(stderr, "\n"); fprintf(stderr, "\n");
@ -273,15 +280,15 @@ mov dword [fs:4], 0x89abcdef
assert(memcmp(buf, "\x67\x45\x23\x01\xef\xcd\xab\x89", 8) == 0); assert(memcmp(buf, "\x67\x45\x23\x01\xef\xcd\xab\x89", 8) == 0);
uc_close(uc); uc_close(uc);
} }
/******************************************************************************/ /******************************************************************************/
int main(int argc, char **argv) { int main(int argc, char **argv)
gdt_demo(); {
gdt_demo();
fprintf(stderr, "success\n");
fprintf(stderr, "success\n");
return 0;
return 0;
} }