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getrandom: test with and without isolation

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also add some comments for why we keep certain old obscure APIs supported
This commit is contained in:
Ralf Jung 2024-05-05 22:38:19 +02:00
parent 6a47bd4cf7
commit a5baa150e3
3 changed files with 16 additions and 23 deletions
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33
src/tools/miri/src/shims/unix/linux/foreign_items.rs
View file

@ -117,6 +117,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
// `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
// is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
id if id == sys_getrandom => {
// Used by getrandom 0.1
// The first argument is the syscall id, so skip over it.
if args.len() < 4 {
throw_ub_format!(
@ -124,7 +125,16 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
args.len()
);
}
getrandom(this, &args[1], &args[2], &args[3], dest)?;
let ptr = this.read_pointer(&args[1])?;
let len = this.read_target_usize(&args[2])?;
// The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
// neither of which have any effect on our current PRNG.
// See <https://github.com/rust-lang/rust/pull/79196> for a discussion of argument sizes.
let _flags = this.read_scalar(&args[3])?.to_i32();
this.gen_random(ptr, len)?;
this.write_scalar(Scalar::from_target_usize(len, this), dest)?;
}
// `futex` is used by some synchronization primitives.
id if id == sys_futex => {
@ -196,24 +206,3 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
Ok(EmulateItemResult::NeedsJumping)
}
}
// Shims the linux `getrandom` syscall.
fn getrandom<'tcx>(
this: &mut MiriInterpCx<'_, 'tcx>,
ptr: &OpTy<'tcx, Provenance>,
len: &OpTy<'tcx, Provenance>,
flags: &OpTy<'tcx, Provenance>,
dest: &MPlaceTy<'tcx, Provenance>,
) -> InterpResult<'tcx> {
let ptr = this.read_pointer(ptr)?;
let len = this.read_target_usize(len)?;
// The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
// neither of which have any effect on our current PRNG.
// See <https://github.com/rust-lang/rust/pull/79196> for a discussion of argument sizes.
let _flags = this.read_scalar(flags)?.to_i32();
this.gen_random(ptr, len)?;
this.write_scalar(Scalar::from_target_usize(len, this), dest)?;
Ok(())
}

3
src/tools/miri/src/shims/windows/foreign_items.rs
View file

@ -513,6 +513,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
throw_machine_stop!(TerminationInfo::Exit { code: code.into(), leak_check: false });
}
"SystemFunction036" => {
// used by getrandom 0.1
// This is really 'RtlGenRandom'.
let [ptr, len] =
this.check_shim(abi, Abi::System { unwind: false }, link_name, args)?;
@ -522,6 +523,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
this.write_scalar(Scalar::from_bool(true), dest)?;
}
"ProcessPrng" => {
// used by `std`
let [ptr, len] =
this.check_shim(abi, Abi::System { unwind: false }, link_name, args)?;
let ptr = this.read_pointer(ptr)?;
@ -530,6 +532,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
this.write_scalar(Scalar::from_i32(1), dest)?;
}
"BCryptGenRandom" => {
// used by getrandom 0.2
let [algorithm, ptr, len, flags] =
this.check_shim(abi, Abi::System { unwind: false }, link_name, args)?;
let algorithm = this.read_scalar(algorithm)?;

3
src/tools/miri/tests/pass-dep/getrandom.rs
View file

@ -1,8 +1,9 @@
// mac-os `getrandom_01` does some pointer shenanigans
//@compile-flags: -Zmiri-permissive-provenance
//@revisions: isolation no_isolation
//@[no_isolation]compile-flags: -Zmiri-disable-isolation
/// Test direct calls of getrandom 0.1 and 0.2.
/// Make sure they work even with isolation enabled (i.e., we do not hit a file-based fallback path).
fn main() {
let mut data = vec![0; 16];
getrandom_01::getrandom(&mut data).unwrap();