1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
//! A simple example showing how to manipulate capabilities.
//!
//! It drops and raises `CAP_SYS_NICE` to show its interaction
//! with `getpriority(2)`.
//!
//! This is an example ONLY: do NOT panic/unwrap/assert
//! in production code!
type ExResult<T> = Result<T, Box<dyn std::error::Error + 'static>>;
fn main() -> ExResult<()> {
use caps::{CapSet, Capability};
// Any process can lower its own priority.
println!("-> Current process priority is {}.", proc_nice());
let r = renice(19);
assert_eq!(r, 0);
println!("Lowered priority to +19.");
println!("-> Current process priority is {}.", proc_nice());
// Without `CAP_SYS_NICE` increasing priority is not possible.
let r = caps::drop(None, CapSet::Effective, Capability::CAP_SYS_NICE);
assert!(r.is_ok());
println!("Dropped CAP_SYS_NICE.");
let has_sys_nice = caps::has_cap(None, CapSet::Effective, Capability::CAP_SYS_NICE);
assert!(has_sys_nice.is_ok());
assert_eq!(has_sys_nice.unwrap_or(true), false);
let r = renice(-20);
assert_eq!(r, -1);
println!("Unprivileged, unable to raise priority to -20.");
// If `CAP_SYS_NICE` is still in permitted set, it can be raised again.
let perm_sys_nice = caps::has_cap(None, CapSet::Permitted, Capability::CAP_SYS_NICE);
assert!(perm_sys_nice.is_ok());
if !perm_sys_nice? {
return Err(
"Try running this again as root/sudo or with CAP_SYS_NICE file capability!".into(),
);
}
let r = caps::raise(None, CapSet::Effective, Capability::CAP_SYS_NICE);
assert!(r.is_ok());
println!("Raised CAP_SYS_NICE.");
// With CAP_SYS_NICE, priority can be raised further.
let r = renice(-20);
assert_eq!(r, 0);
println!("Privileged, raised priority to -20.");
println!("-> Current process priority is {}.", proc_nice());
Ok(())
}
#[cfg(target_env = "musl")]
const PRIO_PROCESS: i32 = libc::PRIO_PROCESS;
#[cfg(not(target_env = "musl"))]
const PRIO_PROCESS: u32 = libc::PRIO_PROCESS as u32;
fn renice(prio: libc::c_int) -> libc::c_int {
// This is not proper logic, as it does not record errno value on error.
unsafe { libc::setpriority(PRIO_PROCESS, 0, prio) }
}
fn proc_nice() -> libc::c_int {
// This is not proper logic, as it does not special-case -1 nor record errno.
let r = unsafe { libc::getpriority(PRIO_PROCESS as u32, 0) };
if r == -1 {
panic!("getpriority failed.");
}
r
}
|
