1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246
#![feature(fn_traits)]
#![feature(unboxed_closures)]
#![feature(tuple_trait)]
#![feature(naked_functions)]
#![feature(auto_traits)]
#![feature(negative_impls)]
use core::ffi::CStr;
use std::{cell::UnsafeCell, marker::Tuple, mem::MaybeUninit};
pub use secgate_macros::*;
use twizzler_abi::object::ObjID;
pub mod util;
/// Enum of possible return codes, similar to [Result], but with specific
/// variants of possible failures of initializing or invoking the secure gate call.
#[derive(Debug, Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Hash)]
#[repr(C, u32)]
pub enum SecGateReturn<T> {
/// Call succeeded, and returned T.
Success(T),
/// Permission was denied for this call.
PermissionDenied,
/// The callee panic'd inside the other compartment.
CalleePanic,
/// The call went through, but no return value was given.
NoReturnValue,
}
impl<T> SecGateReturn<T> {
#[track_caller]
pub fn unwrap(self) -> T {
match self {
SecGateReturn::Success(data) => data,
_ => panic!("failed to unwrap non-successful secure gate return"),
}
}
pub fn ok(self) -> Option<T> {
match self {
SecGateReturn::Success(x) => Some(x),
_ => None,
}
}
}
/// A struct of information about a secure gate. These are auto-generated by the
/// [crate::secure_gate] macro, and stored in a special ELF section (.twz_secgate_info) as an array.
/// The dynamic linker and monitor can then use this to easily enumerate gates.
#[repr(C)]
pub struct SecGateInfo<F> {
/// A pointer to the implementation entry function. This must be a pointer, and we statically
/// check that is has the same size as usize (sorry cheri, we'll fix this another time)
pub imp: F,
/// The name of this secure gate. This must be a pointer to a null-terminated C string.
name: *const i8,
}
impl<F> SecGateInfo<F> {
pub const fn new(imp: F, name: &'static CStr) -> Self {
Self {
imp,
name: name.as_ptr(),
}
}
pub fn name(&self) -> &CStr {
// Safety: we only ever construct self from a static CStr.
unsafe { CStr::from_ptr(self.name) }
}
}
// Safety: If F is Send, we are too because the name field points to a static C string that cannot
// be written to.
unsafe impl<F: Send> Send for SecGateInfo<F> {}
// Safety: If F is Sync, we are too because the name field points to a static C string that cannot
// be written to.
unsafe impl<F: Sync> Sync for SecGateInfo<F> {}
/// Minimum alignment of secure trampolines.
pub const SECGATE_TRAMPOLINE_ALIGN: usize = 0x10;
/// Non-generic and non-pointer-based SecGateInfo, for use during dynamic linking.
pub type RawSecGateInfo = SecGateInfo<usize>;
// Ensure that these are the same size because the dynamic linker uses the raw variant.
static_assertions::assert_eq_size!(RawSecGateInfo, SecGateInfo<&fn()>);
/// Arguments that will be passed to the secure call. Concrete versions of this are generated by the
/// macro.
#[derive(Clone, Copy)]
#[repr(C)]
pub struct Arguments<Args: Tuple + Crossing + Copy> {
args: Args,
}
impl<Args: Tuple + Crossing + Copy> Arguments<Args> {
pub fn with_alloca<F, R>(args: Args, f: F) -> R
where
F: FnOnce(&mut Self) -> R,
{
alloca::alloca(|stack_space| {
stack_space.write(Self { args });
// Safety: we init the MaybeUninit just above.
f(unsafe { stack_space.assume_init_mut() })
})
}
pub fn into_inner(self) -> Args {
self.args
}
}
/// Return value to be filled by the secure call. Concrete versions of this are generated by the
/// macro.
#[derive(Copy)]
#[repr(C)]
pub struct Return<T: Crossing + Copy> {
isset: bool,
ret: MaybeUninit<T>,
}
impl<T: Copy + Crossing> Clone for Return<T> {
fn clone(&self) -> Self {
*self
}
}
impl<T: Crossing + Copy> Return<T> {
pub fn with_alloca<F, R>(f: F) -> R
where
F: FnOnce(&mut Self) -> R,
{
alloca::alloca(|stack_space| {
stack_space.write(Self {
isset: false,
ret: MaybeUninit::uninit(),
});
// Safety: we init the MaybeUninit just above.
f(unsafe { stack_space.assume_init_mut() })
})
}
/// If a previous call to set is made, or this was constructed by new(), then into_inner
/// returns the inner value. Otherwise, returns None.
pub fn into_inner(self) -> Option<T> {
if self.isset {
Some(unsafe { self.ret.assume_init() })
} else {
None
}
}
/// Construct a new, uninitialized Self.
pub fn new_uninit() -> Self {
Self {
isset: false,
ret: MaybeUninit::uninit(),
}
}
/// Set the inner value. Future call to into_inner will return Some(val).
pub fn set(&mut self, val: T) {
self.ret.write(val);
self.isset = true;
}
}
/// An auto trait that limits the types that can be send across to another compartment. These are:
/// 1. Types other than references, UnsafeCell, raw pointers, slices.
/// 2. #[repr(C)] structs and enums made from Crossing types.
///
/// # Safety
/// The type must meet the above requirements.
pub unsafe auto trait Crossing {}
impl<T> !Crossing for &T {}
impl<T> !Crossing for &mut T {}
impl<T> !Crossing for UnsafeCell<T> {}
impl<T> !Crossing for *const T {}
impl<T> !Crossing for *mut T {}
impl<T> !Crossing for &[T] {}
impl<T> !Crossing for &mut [T] {}
unsafe impl<T: Crossing + Copy> Crossing for SecGateReturn<T> {}
/// Required to put in your source if you call any secure gates.
// TODO: this isn't ideal, but it's the only solution I have at the moment. For some reason,
// the linker doesn't even bother linking the libcalloca.a library that alloca creates. This forces
// that to happen.
#[macro_export]
macro_rules! secgate_prelude {
() => {
#[link(name = "calloca", kind = "static")]
extern "C" {
pub fn c_with_alloca();
}
};
}
#[derive(Debug, Clone, Copy, PartialEq, PartialOrd, Ord, Eq, Hash)]
#[repr(C)]
pub struct GateCallInfo {
thread_id: ObjID,
src_ctx: ObjID,
}
impl GateCallInfo {
/// Allocate a new GateCallInfo on the stack for the closure.
pub fn with_alloca<F, R>(thread_id: ObjID, src_ctx: ObjID, f: F) -> R
where
F: FnOnce(&mut Self) -> R,
{
alloca::alloca(|stack_space| {
stack_space.write(Self { thread_id, src_ctx });
// Safety: we init the MaybeUninit just above.
f(unsafe { stack_space.assume_init_mut() })
})
}
/// Get the ID of the source context, or None if the call was not cross-context.
pub fn source_context(&self) -> Option<ObjID> {
if self.src_ctx.as_u128() == 0 {
None
} else {
Some(self.src_ctx)
}
}
/// Get the ID of the calling thread.
pub fn thread_id(&self) -> ObjID {
if self.thread_id.as_u128() == 0 {
twizzler_abi::syscall::sys_thread_self_id()
} else {
self.thread_id
}
}
/// Ensures that the data is filled out (may read thread ID from kernel if necessary).
pub fn canonicalize(self) -> Self {
Self {
thread_id: self.thread_id(),
src_ctx: self.src_ctx,
}
}
}