TSS GDT Gate

[0xBADC0DE]

Is my code for my TSS GDT Gate good?

Code: Select all

struct KeGDTEntry gdte[6];
struct KeGDTPtr gdt;




void KeGDTSetGate(int num, unsigned long base, unsigned long limit, unsigned char access,unsigned char gran)
{
   gdte[num].base_low = (base & 0xFFFF);
   gdte[num].base_middle = (base >> 16) & 0xFF;
   gdte[num].base_high = (base >> 24) & 0xFF;
   gdte[num].limit_low = (limit & 0xFFFF);
   gdte[num].granularity = ((limit >> 16) & 0x0F);
   gdte[num].granularity |= (gran & 0xF0);
   gdte[num].access = access;
}

void KeGDTSetTSS(int num)
{
   gdte[num].base_low = 0;
   gdte[num].base_middle=0;
   gdte[num].base_high=0;
   gdte[num].limit_low = 103;
   gdte[num].access = 0x89;
   gdte[num].granularity = 0;

}

void KeGDTInstall()
{
   gdt.limit = (sizeof(struct KeGDTEntry)*6) - 1;
   gdt.base = (unsigned int)&gdte;

   /* [0x00] */   KeGDTSetGate(0,0,0,0,0);
   /* [0x08] */   KeGDTSetGate(1,0,0xFFFFFFFF,0x9A,0xCF); // Ring0 CS
   /* [0x10] */   KeGDTSetGate(2,0,0xFFFFFFFF,0x92,0xCF); // Ring0 DS
   /* [0x18] */   KeGDTSetTSS(3);
   /* [0x20] */   KeGDTSetGate(4,0,0xFFFFFFFF,0xFA,0xCF); // Ring3 CS
   /* [0x28] */   KeGDTSetGate(5,0,0xFFFFFFFF,0xF2,0xCF); // Ring3 DS

   KeSetGDT();
}

[Pype.Clicker]

i don't see why you call them "gates": CS and DS are loaded with _segments_, not gates.

I think you should read about TSSes again too: a TSS typically _do_ have a base address so i don't see why you load it with 0 by default.

[0Scoder]

yes, like pype said you need to change the naming for your functions. Also, seen as the 'gate' code you use seems to be for segments, you will also need a function for adding gate descriptors.