redhook is a helper crate for writing interposition libraries
(LD_PRELOAD
, DYLD_INSERT_LIBRARIES
, etc.) in Rust.
To use redhook, add the lines
#[macro_use]
extern crate redhook;
to your library, then use the hook!
macro to declare the function you
want to hook, and the name you want to give to your hook function:
hook! {
unsafe fn existing_function(x: i32) -> i32 => my_function {
42
}
}
To access the underlying function, use real!(existing_function)
.
Compile your library as a dylib
, which can be done via
rustc --crate-type=dylib
, or by adding
[lib]
name = "mylib"
crate_type = ["dylib"]
to your Cargo.toml
. Then find the resulting .so
file (./mylib.so
for rustc, or inside target
for Cargo) and set the LD_PRELOAD
environment variable to that.
There are a few examples included, as separate crates:
geofft@cactuar:~/src/rust/redhook/examples/readlinkspy$ cargo build
Compiling redhook v0.0.1 (file:///home/geofft/src/rust/redhook/examples/readlinkspy)
Compiling redhook_ex_readlinkspy v0.0.1 (file:///home/geofft/src/rust/redhook/examples/readlinkspy)
geofft@cactuar:~/src/rust/redhook/examples/readlinkspy$ LD_PRELOAD=target/debug/libreadlinkspy.so ls -l /bin/sh
readlink("/bin/sh")
lrwxrwxrwx 1 root root 4 Feb 19 2014 /bin/sh -> dash
geofft@cactuar:~/src/rust/redhook/examples/fakeroot$ cargo build
geofft@cactuar:~/src/rust/redhook/examples/fakeroot$ LD_PRELOAD=target/debug/libfakeroot.so id
uid=0(root) gid=1001(geofft) euid=1001(geofft) groups=1001(geofft),27(sudo),111(sbuild)
redhook currently supports building interposition libraries for
LD_PRELOAD
on glibc (GNU/Linux) and DYLD_INSERT_LIBRARIES
on Apple's
libc (Mac OS X) from the same source code. If you're interested in
support for other platforms, please file an issue or pull request.
redhook is named after the Red Hook
neighborhood in Brooklyn, New York. Portions of the implementation
borrow heavily from concepts in @Kimundi's
lazy_static!
macro.
redhook is free software, available under the terms of the 2-clause BSD license.