Пример #1
0
func packAddrs(u models.Usercorn, addrs []uint64) ([]byte, error) {
	buf := make([]byte, int(u.Bits())/8*(len(addrs)+1))
	pos := buf
	for _, v := range addrs {
		x, err := u.PackAddr(pos, v)
		if err != nil {
			return nil, err
		}
		pos = pos[len(x):]
	}
	return buf, nil
}
Пример #2
0
func StackInit(u models.Usercorn, args, env []string, auxv []byte) error {
	if _, err := u.Push(0); err != nil {
		return err
	}
	if len(args) > 0 {
		if _, err := u.PushBytes([]byte(args[0] + "\x00")); err != nil {
			return err
		}
	}
	// push argv and envp strings
	envp, err := pushStrings(u, env...)
	if err != nil {
		return err
	}
	argv, err := pushStrings(u, args...)
	if err != nil {
		return err
	}
	// precalc envp -> argc for stack alignment
	envpb, err := packAddrs(u, envp)
	if err != nil {
		return err
	}
	argvb, err := packAddrs(u, argv)
	if err != nil {
		return err
	}
	var tmp [8]byte
	argcb, err := u.PackAddr(tmp[:], uint64(len(argv)))
	init := append(argcb, argvb...)
	init = append(init, envpb...)
	// align stack pointer
	sp, _ := u.RegRead(u.Arch().SP)
	sp &= ^uint64(15)
	off := len(init) & 15
	if off > 0 {
		sp -= uint64(16 - off)
	}
	u.RegWrite(u.Arch().SP, sp)
	// auxv
	if len(auxv) > 0 {
		if _, err := u.PushBytes(auxv); err != nil {
			return err
		}
	}
	// write envp -> argc
	u.PushBytes(init)
	return err
}
Пример #3
0
func StackInit(u models.Usercorn, args, env []string) error {
	exe := u.Exe()
	addr, err := u.PushBytes([]byte(exe + "\x00"))
	if err != nil {
		return err
	}
	var tmp [8]byte
	auxv, err := u.PackAddr(tmp[:], addr)
	if err != nil {
		return err
	}
	err = posix.StackInit(u, args, env, auxv)
	if err != nil {
		return err
	}
	// offset to mach_header at exe[0:] in guest memory
	textOffset, _, _ := u.Loader().Header()
	offset := u.Base() + textOffset
	_, err = u.Push(offset)
	return err
}
Пример #4
0
func writeAddr(u models.Usercorn, addr, val uint64) {
	var buf [4]byte
	u.PackAddr(buf[:], val)
	u.MemWrite(addr, buf[:])
}
Пример #5
0
func setupTraps(u models.Usercorn, kernel *ArmLinuxKernel) error {
	// handle arm kernel traps
	// https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt
	if err := u.MemMap(0xffff0000, 0x10000); err != nil {
		return err
	}
	for addr := 0; addr < 0x10000; addr += 4 {
		// write "bx lr" to all kernel trap addresses so they will return
		bxlr := []byte{0x1e, 0xff, 0x2f, 0xe1}
		if err := u.MemWrite(0xffff0000+uint64(addr), bxlr); err != nil {
			return err
		}
	}
	_, err := u.HookAdd(uc.HOOK_CODE, func(_ uc.Unicorn, addr uint64, size uint32) {
		switch addr {
		case 0xffff0fa0:
			// __kuser_memory_barrier
			// *shrug*
		case 0xffff0f60:
			// __kuser_cmpxchg64
			// TODO: DRY possible here?
			oldval, _ := u.RegRead(uc.ARM_REG_R0)
			newval, _ := u.RegRead(uc.ARM_REG_R1)
			ptr, _ := u.RegRead(uc.ARM_REG_R2)
			var tmp [8]byte
			var status uint64
			if err := u.MemReadInto(tmp[:], ptr); err != nil {
				// error
			} else if u.ByteOrder().Uint64(tmp[:]) == oldval {
				u.ByteOrder().PutUint64(tmp[:], newval)
				u.MemWrite(ptr, tmp[:])
				status = 1
			}
			u.RegWrite(uc.ARM_REG_R0, status)
		case 0xffff0fc0:
			// __kuser_cmpxchg
			// TODO: would this throw a segfault?
			// TODO: flags are not set
			oldval, _ := u.RegRead(uc.ARM_REG_R0)
			newval, _ := u.RegRead(uc.ARM_REG_R1)
			ptr, _ := u.RegRead(uc.ARM_REG_R2)
			var tmp [4]byte
			var status uint64
			if err := u.MemReadInto(tmp[:], ptr); err != nil {
				// error
			} else if u.UnpackAddr(tmp[:]) == oldval {
				u.PackAddr(tmp[:], newval)
				u.MemWrite(ptr, tmp[:])
				status = 1
			}
			u.RegWrite(uc.ARM_REG_R0, status)
		case 0xffff0fe0:
			// __kuser_get_tls
			u.RegWrite(uc.ARM_REG_R0, kernel.tls)
		case 0xffff0ffc:
			// __kuser_helper_version
			u.RegWrite(uc.ARM_REG_R0, 2)
		default:
			panic(fmt.Sprintf("unsupported kernel trap: 0x%x\n", addr))
		}
	}, 0xffff0000, 0xffffffff)
	if err != nil {
		return err
	}
	return nil
}