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kprobe.rs
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kprobe.rs
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//! Kernel space probes.
use std::io;
use thiserror::Error;
use crate::{
generated::bpf_prog_type::BPF_PROG_TYPE_KPROBE,
programs::{
define_link_wrapper, load_program,
perf_attach::{PerfLink, PerfLinkId},
probe::{attach, ProbeKind},
OwnedLink, ProgramData, ProgramError,
},
};
/// A kernel probe.
///
/// Kernel probes are eBPF programs that can be attached to almost any function inside
/// the kernel. They can be of two kinds:
///
/// - `kprobe`: get attached to the *start* of the target functions
/// - `kretprobe`: get attached to the *return address* of the target functions
///
/// # Minimum kernel version
///
/// The minimum kernel version required to use this feature is 4.1.
///
/// # Examples
///
/// ```no_run
/// # let mut bpf = Bpf::load_file("ebpf_programs.o")?;
/// use aya::{Bpf, programs::KProbe};
/// use std::convert::TryInto;
///
/// let program: &mut KProbe = bpf.program_mut("intercept_wakeups").unwrap().try_into()?;
/// program.load()?;
/// program.attach("try_to_wake_up", 0)?;
/// # Ok::<(), aya::BpfError>(())
/// ```
#[derive(Debug)]
#[doc(alias = "BPF_PROG_TYPE_KPROBE")]
pub struct KProbe {
pub(crate) data: ProgramData<KProbeLink>,
pub(crate) kind: ProbeKind,
}
impl KProbe {
/// Loads the program inside the kernel.
pub fn load(&mut self) -> Result<(), ProgramError> {
load_program(BPF_PROG_TYPE_KPROBE, &mut self.data)
}
/// Returns `KProbe` if the program is a `kprobe`, or `KRetProbe` if the
/// program is a `kretprobe`.
pub fn kind(&self) -> ProbeKind {
self.kind
}
/// Attaches the program.
///
/// Attaches the probe to the given function name inside the kernel. If
/// `offset` is non-zero, it is added to the address of the target
/// function.
///
/// If the program is a `kprobe`, it is attached to the *start* address of the target function.
/// Conversely if the program is a `kretprobe`, it is attached to the return address of the
/// target function.
///
/// The returned value can be used to detach from the given function, see [KProbe::detach].
pub fn attach(&mut self, fn_name: &str, offset: u64) -> Result<KProbeLinkId, ProgramError> {
attach(&mut self.data, self.kind, fn_name, offset, None)
}
/// Detaches the program.
///
/// See [KProbe::attach].
pub fn detach(&mut self, link_id: KProbeLinkId) -> Result<(), ProgramError> {
self.data.links.remove(link_id)
}
/// 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.
pub fn take_link(
&mut self,
link_id: KProbeLinkId,
) -> Result<OwnedLink<KProbeLink>, ProgramError> {
Ok(OwnedLink::new(self.data.take_link(link_id)?))
}
}
define_link_wrapper!(
/// The link used by [KProbe] programs.
KProbeLink,
/// The type returned by [KProbe::attach]. Can be passed to [KProbe::detach].
KProbeLinkId,
PerfLink,
PerfLinkId
);
/// The type returned when attaching a [`KProbe`] fails.
#[derive(Debug, Error)]
pub enum KProbeError {
/// Error detaching from debugfs
#[error("`{filename}`")]
FileError {
/// The file name
filename: String,
/// The [`io::Error`] returned from the file operation
#[source]
io_error: io::Error,
},
}