Struct aya::programs::fentry::FEntry

pub struct FEntry { /* private fields */ }

A program that can be attached to the entry point of (almost) any kernel function.

FEntry programs are similar to kprobes, but the difference is that fentry has practically zero overhead to call before kernel function. Fentry programs can be also attached to other eBPF programs.

Minimum kernel version

The minimum kernel version required to use this feature is 5.5.

Examples

use aya::{Bpf, programs::FEntry, BtfError, Btf};
use std::convert::TryInto;

let btf = Btf::from_sys_fs()?;
let program: &mut FEntry = bpf.program_mut("filename_lookup").unwrap().try_into()?;
program.load("filename_lookup", &btf)?;
program.attach()?;

Implementations

impl FEntry

pub fn load(&mut self, fn_name: &str, btf: &Btf) -> Result<(), ProgramError>

Loads the program inside the kernel.

Loads the program so it’s executed when the kernel function fn_name is entered. The btf argument must contain the BTF info for the running kernel.

pub fn attach(&mut self) -> Result<FEntryLinkId, ProgramError>

Attaches the program.

The returned value can be used to detach, see FEntry::detach.

pub fn detach(&mut self, link_id: FEntryLinkId) -> Result<(), ProgramError>

Detaches the program.

See FEntry::attach.

pub fn take_link(
    &mut self,
    link_id: FEntryLinkId
) -> Result<OwnedLink<FEntryLink>, ProgramError>

Takes ownership of the link referenced by the provided link_id.

The link will be detached on Drop and the caller is now responsible for managing its lifetime.

impl FEntry

pub fn unload(&mut self) -> Result<(), ProgramError>

Unloads the program from the kernel.

Links will be detached before unloading the program. Note that owned links obtained using take_link() will not be detached.

Trait Implementations

impl Debug for FEntry

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl ProgramFd for FEntry

fn fd(&self) -> Option<RawFd>

Returns the RawFd of the program if it has been loaded, or None

impl ProgramFd for &mut FEntry

fn fd(&self) -> Option<RawFd>

Returns the RawFd of the program if it has been loaded, or None

impl<'a> TryFrom<&'a Program> for &'a FEntry

type Error = ProgramError

The type returned in the event of a conversion error.

fn try_from(program: &'a Program) -> Result<&'a FEntry, ProgramError>

Performs the conversion.

impl<'a> TryFrom<&'a mut Program> for &'a mut FEntry

type Error = ProgramError

The type returned in the event of a conversion error.

fn try_from(program: &'a mut Program) -> Result<&'a mut FEntry, ProgramError>

Performs the conversion.