2016-03-27 20:04:33 +00:00
|
|
|
#!/usr/bin/env ruby
|
|
|
|
|
require 'unicorn'
|
|
|
|
|
require 'unicorn/x86_const'
|
|
|
|
|
|
|
|
|
|
include Unicorn
|
|
|
|
|
|
|
|
|
|
F_GRANULARITY = 0x8
|
|
|
|
|
F_PROT_32 = 0x4
|
|
|
|
|
F_LONG = 0x2
|
|
|
|
|
F_AVAILABLE = 0x1
|
|
|
|
|
|
|
|
|
|
A_PRESENT = 0x80
|
|
|
|
|
|
|
|
|
|
A_PRIV_3 = 0x60
|
|
|
|
|
A_PRIV_2 = 0x40
|
|
|
|
|
A_PRIV_1 = 0x20
|
|
|
|
|
A_PRIV_0 = 0x0
|
|
|
|
|
|
2017-08-29 10:03:52 +00:00
|
|
|
A_CODE = 0x8
|
|
|
|
|
A_DATA = 0x0
|
2016-03-27 20:04:33 +00:00
|
|
|
A_TSS = 0x0
|
|
|
|
|
A_GATE = 0x0
|
|
|
|
|
|
|
|
|
|
A_DATA_WRITABLE = 0x2
|
|
|
|
|
A_CODE_READABLE = 0x2
|
|
|
|
|
|
|
|
|
|
A_DIR_CON_BIT = 0x4
|
|
|
|
|
|
|
|
|
|
S_GDT = 0x0
|
|
|
|
|
S_LDT = 0x4
|
|
|
|
|
S_PRIV_3 = 0x3
|
|
|
|
|
S_PRIV_2 = 0x2
|
|
|
|
|
S_PRIV_1 = 0x1
|
|
|
|
|
S_PRIV_0 = 0x0
|
|
|
|
|
|
|
|
|
|
def create_selector(idx, flags)
|
|
|
|
|
to_ret = flags
|
|
|
|
|
to_ret |= idx << 3
|
|
|
|
|
return to_ret
|
|
|
|
|
end
|
|
|
|
|
|
|
|
|
|
def create_gdt_entry(base, limit, access, flags)
|
|
|
|
|
|
|
|
|
|
to_ret = limit & 0xffff;
|
|
|
|
|
to_ret |= (base & 0xffffff) << 16;
|
|
|
|
|
to_ret |= (access & 0xff) << 40;
|
|
|
|
|
to_ret |= ((limit >> 16) & 0xf) << 48;
|
|
|
|
|
to_ret |= (flags & 0xff) << 52;
|
|
|
|
|
to_ret |= ((base >> 24) & 0xff) << 56;
|
|
|
|
|
return [to_ret].pack('Q')
|
|
|
|
|
end
|
|
|
|
|
|
|
|
|
|
def write_gdt(uc, gdt, mem)
|
|
|
|
|
gdt.each_index do |idx|
|
|
|
|
|
offset = idx * GDT_ENTRY_SIZE
|
|
|
|
|
uc.mem_write(mem + offset, gdt[idx])
|
|
|
|
|
end
|
|
|
|
|
end
|
|
|
|
|
|
|
|
|
|
CODE_ADDR = 0x40000
|
|
|
|
|
CODE_SIZE = 0x1000
|
|
|
|
|
|
|
|
|
|
GDT_ADDR = 0x3000
|
|
|
|
|
GDT_LIMIT = 0x1000
|
|
|
|
|
GDT_ENTRY_SIZE = 0x8
|
|
|
|
|
|
|
|
|
|
GS_SEGMENT_ADDR = 0x5000
|
|
|
|
|
GS_SEGMENT_SIZE = 0x1000
|
|
|
|
|
|
|
|
|
|
uc = Uc.new UC_ARCH_X86, UC_MODE_32
|
|
|
|
|
|
|
|
|
|
uc.mem_map(GDT_ADDR, GDT_LIMIT)
|
|
|
|
|
uc.mem_map(GS_SEGMENT_ADDR, GS_SEGMENT_SIZE)
|
|
|
|
|
uc.mem_map(CODE_ADDR, CODE_SIZE)
|
|
|
|
|
|
|
|
|
|
gdt = Array.new (31) {|i| create_gdt_entry(0,0,0,0)}
|
|
|
|
|
gdt[15] = create_gdt_entry(GS_SEGMENT_ADDR, GS_SEGMENT_SIZE, A_PRESENT | A_DATA | A_DATA_WRITABLE | A_PRIV_3 | A_DIR_CON_BIT, F_PROT_32)
|
|
|
|
|
gdt[16] = create_gdt_entry(0, 0xfffff000 , A_PRESENT | A_DATA | A_DATA_WRITABLE | A_PRIV_3 | A_DIR_CON_BIT, F_PROT_32) # Data Segment
|
|
|
|
|
gdt[17] = create_gdt_entry(0, 0xfffff000 , A_PRESENT | A_CODE | A_CODE_READABLE | A_PRIV_3 | A_DIR_CON_BIT, F_PROT_32) # Code Segment
|
|
|
|
|
gdt[18] = create_gdt_entry(0, 0xfffff000 , A_PRESENT | A_DATA | A_DATA_WRITABLE | A_PRIV_0 | A_DIR_CON_BIT, F_PROT_32) # Stack Segment
|
|
|
|
|
|
|
|
|
|
write_gdt(uc, gdt, GDT_ADDR)
|
|
|
|
|
uc.reg_write(UC_X86_REG_GDTR, [0, GDT_ADDR, gdt.length * GDT_ENTRY_SIZE-1, 0x0])
|
|
|
|
|
|
|
|
|
|
selector = create_selector(15, S_GDT | S_PRIV_3)
|
|
|
|
|
uc.reg_write(UC_X86_REG_GS, selector)
|
|
|
|
|
|
|
|
|
|
selector = create_selector(16, S_GDT | S_PRIV_3)
|
|
|
|
|
uc.reg_write(UC_X86_REG_DS, selector)
|
|
|
|
|
|
|
|
|
|
selector = create_selector(17, S_GDT | S_PRIV_3)
|
|
|
|
|
uc.reg_write(UC_X86_REG_CS, selector)
|
|
|
|
|
|
|
|
|
|
selector = create_selector(18, S_GDT | S_PRIV_0)
|
|
|
|
|
uc.reg_write(UC_X86_REG_SS, selector)
|
|
|
|
|
|
|
|
|
|
|
