base/sys/linux/
capabilities.rs

1// Copyright 2019 The ChromiumOS Authors
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use libc::c_int;
6use libc::c_void;
7
8use super::errno_result;
9use super::Result;
10
11#[allow(non_camel_case_types)]
12type cap_t = *mut c_void;
13
14#[link(name = "cap")]
15extern "C" {
16    fn cap_init() -> cap_t;
17    fn cap_free(ptr: *mut c_void) -> c_int;
18    fn cap_set_proc(cap: cap_t) -> c_int;
19}
20
21/// Drops all capabilities (permitted, inheritable, and effective) from the current process.
22pub fn drop_capabilities() -> Result<()> {
23    // SAFETY:
24    // Safe because we do not actually manipulate any memory handled by libcap
25    // and we check errors.
26    unsafe {
27        let caps = cap_init();
28        if caps.is_null() {
29            return errno_result();
30        }
31
32        // Freshly initialized capabilities do not have any bits set, so applying them
33        // will drop all capabilities from the process.
34        // Safe because we will check the result and otherwise do not touch the memory.
35        let ret = cap_set_proc(caps);
36        // We need to free capabilities regardless of success of the operation above.
37        cap_free(caps);
38        // Now check if we managed to apply (drop) capabilities.
39        if ret < 0 {
40            return errno_result();
41        }
42    }
43    Ok(())
44}
base/sys/linux/capabilities.rs

base/sys/linux/
capabilities.rs
