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stalker.rs
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stalker.rs
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/*
* Copyright © 2020-2021 Keegan Saunders
*
* Licence: wxWindows Library Licence, Version 3.1
*/
//! Code tracing engine.
//!
//! More details about the Frida Stalker can be found on the [Stalker page](https://frida.re/docs/stalker/)
//! of the Frida documentation.
//!
//! The Rust interface to the Stalker provides a best-effort "safe" interface,
//! but naturally runtime code modification takes great caution and
//! these bindings cannot prevent all types of misbehaviour resulting in misuse
//! of the Stalker interface.
//!
//! # Examples
//! To trace the current thread with the Stalker, create a new [`Stalker`] and [`Transformer`] and call
//! [`Stalker::follow_me()`]:
//! ```
//! # use frida_gum::Gum;
//! # use frida_gum::stalker::{Stalker, Transformer};
//! #[cfg(feature = "event-sink")]
//! use frida_gum::stalker::NoneEventSink;
//! let gum = unsafe { Gum::obtain() };
//! let mut stalker = Stalker::new(&gum);
//!
//! let transformer = Transformer::from_callback(&gum, |basic_block, _output| {
//! for instr in basic_block {
//! instr.keep();
//! }
//! });
//!
//! #[cfg(feature = "event-sink")]
//! stalker.follow_me::<NoneEventSink>(&transformer, None);
//!
//! #[cfg(not(feature = "event-sink"))]
//! stalker.follow_me(&transformer);
//!
//! stalker.unfollow_me();
//! ```
use frida_gum_sys as gum_sys;
use std::marker::PhantomData;
use std::os::raw::c_void;
use crate::{Gum, MemoryRange, NativePointer};
#[cfg(feature = "event-sink")]
mod event_sink;
#[cfg(feature = "event-sink")]
pub use event_sink::*;
mod transformer;
pub use transformer::*;
#[cfg(feature = "event-sink")]
#[cfg_attr(doc_cfg, doc(cfg(feature = "event-sink")))]
pub struct NoneEventSink;
#[cfg(feature = "event-sink")]
#[cfg_attr(doc_cfg, doc(cfg(feature = "event-sink")))]
impl EventSink for NoneEventSink {
fn query_mask(&mut self) -> EventMask {
unreachable!()
}
fn start(&mut self) {
unreachable!()
}
fn process(&mut self, _event: &Event) {
unreachable!()
}
fn flush(&mut self) {
unreachable!()
}
fn stop(&mut self) {
unreachable!()
}
}
/// Code tracing engine interface.
pub struct Stalker<'a> {
stalker: *mut frida_gum_sys::GumStalker,
phantom: PhantomData<&'a frida_gum_sys::GumStalker>,
}
impl<'a> Stalker<'a> {
/// Checks if the Stalker is supported on the current platform.
pub fn is_supported(_gum: &Gum) -> bool {
unsafe { frida_gum_sys::gum_stalker_is_supported() != 0 }
}
/// Create a new Stalker.
///
/// This call has the overhead of checking if the Stalker is
/// available on the current platform, as creating a Stalker on an
/// unsupported platform results in unwanted behaviour.
pub fn new<'b>(gum: &'b Gum) -> Stalker
where
'b: 'a,
{
assert!(Self::is_supported(gum));
Stalker {
stalker: unsafe { frida_gum_sys::gum_stalker_new() },
phantom: PhantomData,
}
}
/// Exclude a range of address from the Stalker engine.
///
/// This exclusion will prevent the Stalker from tracing into the memory range,
/// reducing instrumentation overhead as well as potential noise from the [`EventSink`].
pub fn exclude(&mut self, range: &MemoryRange) {
unsafe { gum_sys::gum_stalker_exclude(self.stalker, &range.memory_range as *const _) };
}
/// Set how many times a piece of code needs to be executed before it is assumed it can be
/// trusted to not mutate.
///
/// Specify -1 for no trust (slow), 0 to trust code from the get-go,
/// and N to trust code after it has been executed N times. Defaults to 1.
pub fn set_trust_threshold(&mut self, threshold: i32) {
unsafe { gum_sys::gum_stalker_set_trust_threshold(self.stalker, threshold) };
}
/// Get the Stalker trust treshold, see [`Stalker::set_trust_threshold()`] for more details.
pub fn get_trust_threshold(&self) -> i32 {
unsafe { gum_sys::gum_stalker_get_trust_threshold(self.stalker) }
}
/// Flush all buffered events.
pub fn flush(&mut self) {
unsafe { gum_sys::gum_stalker_flush(self.stalker) }
}
pub fn stop(&mut self) {
unsafe { gum_sys::gum_stalker_stop(self.stalker) }
}
/// Free accumulated memory at a safe point after [`Stalker::unfollow_me()`].
///
/// This is needed to avoid race-conditions where the thread just unfollowed is executing its last instructions.
pub fn garbage_collect(&mut self) -> bool {
unsafe { gum_sys::gum_stalker_garbage_collect(self.stalker) != 0 }
}
/// Begin the Stalker on the current thread.
///
/// A [`Transformer`] must be specified, and will be updated with all events.
///
/// If reusing an existing [`Transformer`], make sure to call [`Stalker::garbage_collect()`]
/// periodically.
#[cfg(feature = "event-sink")]
#[cfg_attr(doc_cfg, doc(cfg(feature = "event-sink")))]
pub fn follow_me<S: EventSink>(
&mut self,
transformer: &Transformer,
event_sink: Option<&mut S>,
) {
let sink = if let Some(sink) = event_sink {
event_sink_transform(sink)
} else {
std::ptr::null_mut()
};
unsafe { gum_sys::gum_stalker_follow_me(self.stalker, transformer.transformer, sink) };
}
/// Begin the Stalker on the current thread.
///
/// A [`Transformer`] must be specified, and will be updated with all events.
///
/// If reusing an existing [`Transformer`], make sure to call [`Stalker::garbage_collect()`]
/// periodically.
#[cfg(not(feature = "event-sink"))]
#[cfg_attr(doc_cfg, doc(cfg(not(feature = "event-sink"))))]
pub fn follow_me(&mut self, transformer: &Transformer) {
unsafe {
gum_sys::gum_stalker_follow_me(
self.stalker,
transformer.transformer,
std::ptr::null_mut(),
)
};
}
/// Stop stalking the current thread.
pub fn unfollow_me(&mut self) {
unsafe { gum_sys::gum_stalker_unfollow_me(self.stalker) };
}
/// Check if the Stalker is running on the current thread.
pub fn is_following_me(&mut self) -> bool {
unsafe { gum_sys::gum_stalker_is_following_me(self.stalker) != 0 }
}
/// Re-activate the Stalker at the specified start point.
pub fn activate(&mut self, start: NativePointer) {
unsafe { gum_sys::gum_stalker_activate(self.stalker, start.0) }
}
/// Pause the Stalker.
pub fn deactivate(&mut self) {
unsafe { gum_sys::gum_stalker_deactivate(self.stalker) }
}
/// Enable (experimental) unwind hooking
pub fn enable_unwind_hooking(&mut self) {
unsafe { gum_sys::gum_stalker_activate_experimental_unwind_support() }
}
}
impl<'a> Drop for Stalker<'a> {
fn drop(&mut self) {
unsafe { gum_sys::g_object_unref(self.stalker as *mut c_void) };
}
}