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// Copyright (C) 2023 Tomasz Kramkowski <tomasz@kramkow.ski>
// SPDX-License-Identifier: MIT
mod pam;
mod passwd;
mod syslog;
use cap_std::fs::{Dir, OpenOptions};
use pam::PAMHandle;
use std::ffi::{c_char, c_int, CStr, CString};
use std::io::{ErrorKind, Write};
use std::panic;
use std::path::Path;
use std::process;
use syslog::{Facility, Level, Priority};
fn create_and_open_dir<P: AsRef<Path> + ?Sized>(
d: &Dir,
path: &P,
) -> std::io::Result<Dir> {
if let Err(e) = d.create_dir(path) {
if e.kind() != ErrorKind::AlreadyExists {
return Err(e);
}
}
d.open_dir(path)
}
struct SessionError;
impl From<std::io::Error> for SessionError {
fn from(_: std::io::Error) -> Self {
SessionError
}
}
const PRIORITY: Priority = Priority {
level: Level::Debug,
facility: Facility::Auth,
};
fn open_session(h: &PAMHandle, mountpoint: &str) -> Result<(), SessionError> {
let user = match h.get_user::<CStr>(None) {
Ok(user) => user,
Err(e) => {
if let Ok(message) =
CString::new(format!("Failure to get username: {e}"))
{
h.syslog(PRIORITY, &message);
}
return Err(SessionError);
}
};
let uid = match passwd::get_uid_by_name(&user) {
Some(uid) => uid.to_string(),
None => {
if let Ok(message) =
CString::new(format!("Failure to map user {user:?} to passwd entry"))
{
h.syslog(PRIORITY, &message);
}
return Err(SessionError);
}
};
let d = Dir::open_ambient_dir(mountpoint, cap_std::ambient_authority())?;
let d = create_and_open_dir(&d, "user")?;
let d = create_and_open_dir(&d, &uid)?;
let d = create_and_open_dir(&d, "leaf")?;
let pid = process::id().to_string();
let mut options = OpenOptions::new();
options.write(true);
let mut procs = d.open_with("cgroup.procs", &options)?;
procs.write_all(pid.as_bytes())?;
Ok(())
}
const CG_MOUNT: &str = "/sys/fs/cgroup";
#[no_mangle]
pub extern "C" fn pam_sm_open_session(
h: &mut PAMHandle,
_flags: c_int,
_argc: c_int,
_argv: *const *const c_char,
) -> c_int {
match panic::catch_unwind(|| open_session(h, CG_MOUNT)) {
Ok(Ok(())) => pam::SUCCESS,
_ => pam::SESSION_ERR,
}
}
#[no_mangle]
pub extern "C" fn pam_sm_close_session(
_h: &mut PAMHandle,
_flags: c_int,
_argc: c_int,
_argv: *const *const c_char,
) -> c_int {
pam::IGNORE
}
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