5 releases
0.1.2 | Nov 24, 2023 |
---|---|
0.1.1 | Nov 19, 2023 |
0.1.1-rc.4 | Nov 14, 2023 |
0.1.1-rc.3 | Nov 13, 2023 |
#6 in #ld-preload
32 downloads per month
Used in upgrayedd
10KB
95 lines
upgrayedd
"Two Ds for a double dose of debugging."
[!WARNING] You do not need this library. Do not use this library, especially in production systems. It is not safe, even if you only use safe Rust with it. It cannot be made safe.
upgrayedd
is a convenience proc macro for building function interposition
tools in Rust. When used in a shared library build (which is the only
way you should be using it), it makes LD_PRELOAD
-style interposition
look like (relatively) idiomatic Rust.
Usage
Interposing on an OpenSSL API:
use upgrayedd::upgrayedd;
#[upgrayedd]
fn X509_VERIFY_PARAM_set_auth_level(param: *mut std::ffi::c_void, level: std::ffi::c_int) {
eprintln!("before!");
unsafe { upgrayedd(param, level) };
eprintln!("after!");
}
Rewriting parameters:
use upgrayedd::upgrayedd;
#[upgrayedd]
fn frobulate(size: libc::size_t) {
unsafe { upgrayedd(size + 42) };
}
Stubbing functions out:
use upgrayedd::upgrayedd;
#[upgrayedd]
fn verify_cert(cert: *mut std::ffi::c_void) -> libc::c_int {
// nothing to see here
1
}
See the docs for more usage examples.
Limitations
- Fundamentally unsafe. Again: please do not use this for anything serious.
- Hooking "basic" routines (like
malloc
andfree
) may or may not work, depending on what you put in your hook. In particular, if you accidentally recurse while holding a lock (which is easy to do when hookingmalloc
and callingprintln!
), you'll probably end up deadlocking. - Bad things will definitely happen if you try to pass Rust types into
wrapped C functions, which
upgrayedd
will happily let you do. - Bad things will definitely happen if you supply the wrong function
signature, which
upgrayedd
will happily let you do. - Only C functions can currently be wrapped; C++ would probably work with small tweaks.
- Currently Linux only. Other OSes would probably work with small tweaks.
Dependencies
~240–680KB
~16K SLoC