mirror of https://github.com/aya-rs/aya
aya: rework links
Remove LinkRef and remove the Rc<RefCell<_>> that was used to store
type-erased link values in ProgramData. Among other things, this allows
`Bpf` to be `Send`, which makes it easier to use it with async runtimes.
Change the link API to:
let link_id = prog.attach(...)?;
...
prog.detach(link_id)?;
Link ids are strongly typed, so it's impossible to eg:
let link_id = uprobe.attach(...)?;
xdp.detach(link_id);
As it would result in a compile time error.
Links are still stored inside ProgramData, and unless detached
explicitly, they are automatically detached when the parent program gets
dropped.
pull/249/head
Alessandro Decina
3 years ago
parent
29d539751a
commit
cb57d10d25
@ -0,0 +1,260 @@
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use libc::{close, dup};
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use std::{
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collections::{hash_map::Entry, HashMap},
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os::unix::prelude::RawFd,
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};
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use crate::{generated::bpf_attach_type, programs::ProgramError, sys::bpf_prog_detach};
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pub(crate) trait Link: std::fmt::Debug + 'static {
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type Id: std::fmt::Debug + std::hash::Hash + Eq + PartialEq;
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fn id(&self) -> Self::Id;
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fn detach(self) -> Result<(), ProgramError>;
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}
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#[derive(Debug)]
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pub(crate) struct LinkMap<T: Link> {
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links: HashMap<T::Id, T>,
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}
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impl<T: Link> LinkMap<T> {
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pub(crate) fn new() -> LinkMap<T> {
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LinkMap {
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links: HashMap::new(),
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}
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}
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pub(crate) fn insert(&mut self, link: T) -> Result<T::Id, ProgramError> {
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let id = link.id();
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match self.links.entry(link.id()) {
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Entry::Occupied(_) => return Err(ProgramError::AlreadyAttached),
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Entry::Vacant(e) => e.insert(link),
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};
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Ok(id)
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}
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pub(crate) fn remove(&mut self, link_id: T::Id) -> Result<(), ProgramError> {
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self.links
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.remove(&link_id)
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.ok_or(ProgramError::NotAttached)?
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.detach()
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}
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}
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impl<T: Link> Drop for LinkMap<T> {
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fn drop(&mut self) {
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for (_, link) in self.links.drain() {
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let _ = link.detach();
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}
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}
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}
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#[derive(Debug, Hash, Eq, PartialEq)]
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pub(crate) struct FdLinkId(pub(crate) RawFd);
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#[derive(Debug)]
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pub(crate) struct FdLink {
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fd: RawFd,
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}
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impl FdLink {
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pub(crate) fn new(fd: RawFd) -> FdLink {
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FdLink { fd }
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}
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}
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impl Link for FdLink {
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type Id = FdLinkId;
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fn id(&self) -> Self::Id {
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FdLinkId(self.fd)
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}
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fn detach(self) -> Result<(), ProgramError> {
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unsafe { close(self.fd) };
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Ok(())
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}
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}
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#[derive(Debug, Hash, Eq, PartialEq)]
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pub(crate) struct ProgAttachLinkId(RawFd, RawFd, bpf_attach_type);
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#[derive(Debug)]
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pub(crate) struct ProgAttachLink {
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prog_fd: RawFd,
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target_fd: RawFd,
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attach_type: bpf_attach_type,
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}
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impl ProgAttachLink {
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pub(crate) fn new(
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prog_fd: RawFd,
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target_fd: RawFd,
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attach_type: bpf_attach_type,
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) -> ProgAttachLink {
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ProgAttachLink {
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prog_fd,
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target_fd: unsafe { dup(target_fd) },
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attach_type,
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}
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}
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}
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impl Link for ProgAttachLink {
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type Id = ProgAttachLinkId;
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fn id(&self) -> Self::Id {
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ProgAttachLinkId(self.prog_fd, self.target_fd, self.attach_type)
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}
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fn detach(self) -> Result<(), ProgramError> {
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let _ = bpf_prog_detach(self.prog_fd, self.target_fd, self.attach_type);
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unsafe { close(self.target_fd) };
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Ok(())
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}
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}
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macro_rules! define_link_wrapper {
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($wrapper:ident, #[$doc:meta] $wrapper_id:ident, $base:ident, $base_id:ident) => {
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#[$doc]
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#[derive(Debug, Hash, Eq, PartialEq)]
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pub struct $wrapper_id($base_id);
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#[derive(Debug)]
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pub(crate) struct $wrapper($base);
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impl crate::programs::Link for $wrapper {
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type Id = $wrapper_id;
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fn id(&self) -> Self::Id {
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$wrapper_id(self.0.id())
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}
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fn detach(self) -> Result<(), ProgramError> {
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self.0.detach()
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}
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}
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impl From<$base> for $wrapper {
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fn from(b: $base) -> $wrapper {
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$wrapper(b)
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}
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}
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};
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}
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pub(crate) use define_link_wrapper;
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#[cfg(test)]
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mod tests {
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use std::{cell::RefCell, rc::Rc};
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use crate::programs::ProgramError;
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use super::{Link, LinkMap};
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#[derive(Debug, Hash, Eq, PartialEq)]
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struct TestLinkId(u8, u8);
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#[derive(Debug)]
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struct TestLink {
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id: (u8, u8),
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detached: Rc<RefCell<u8>>,
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}
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impl TestLink {
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fn new(a: u8, b: u8) -> TestLink {
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TestLink {
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id: (a, b),
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detached: Rc::new(RefCell::new(0)),
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}
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}
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}
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impl Link for TestLink {
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type Id = TestLinkId;
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fn id(&self) -> Self::Id {
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TestLinkId(self.id.0, self.id.1)
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}
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fn detach(self) -> Result<(), ProgramError> {
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*self.detached.borrow_mut() += 1;
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Ok(())
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}
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}
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#[test]
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fn test_link_map() {
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let mut links = LinkMap::new();
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let l1 = TestLink::new(1, 2);
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let l1_detached = Rc::clone(&l1.detached);
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let l2 = TestLink::new(1, 3);
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let l2_detached = Rc::clone(&l2.detached);
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let id1 = links.insert(l1).unwrap();
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let id2 = links.insert(l2).unwrap();
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assert!(*l1_detached.borrow() == 0);
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assert!(*l2_detached.borrow() == 0);
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assert!(links.remove(id1).is_ok());
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assert!(*l1_detached.borrow() == 1);
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assert!(*l2_detached.borrow() == 0);
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assert!(links.remove(id2).is_ok());
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assert!(*l1_detached.borrow() == 1);
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assert!(*l2_detached.borrow() == 1);
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}
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#[test]
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fn test_already_attached() {
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let mut links = LinkMap::new();
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links.insert(TestLink::new(1, 2)).unwrap();
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assert!(matches!(
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links.insert(TestLink::new(1, 2)),
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Err(ProgramError::AlreadyAttached)
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));
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}
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#[test]
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fn test_not_attached() {
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let mut links = LinkMap::new();
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let l1 = TestLink::new(1, 2);
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let l1_id1 = l1.id();
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let l1_id2 = l1.id();
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links.insert(TestLink::new(1, 2)).unwrap();
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links.remove(l1_id1).unwrap();
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assert!(matches!(
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links.remove(l1_id2),
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Err(ProgramError::NotAttached)
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));
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}
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#[test]
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fn test_drop_detach() {
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let l1 = TestLink::new(1, 2);
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let l1_detached = Rc::clone(&l1.detached);
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let l2 = TestLink::new(1, 3);
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let l2_detached = Rc::clone(&l2.detached);
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{
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let mut links = LinkMap::new();
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let id1 = links.insert(l1).unwrap();
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links.insert(l2).unwrap();
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// manually remove one link
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assert!(links.remove(id1).is_ok());
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assert!(*l1_detached.borrow() == 1);
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assert!(*l2_detached.borrow() == 0);
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}
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// remove the other on drop
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assert!(*l1_detached.borrow() == 1);
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assert!(*l2_detached.borrow() == 1);
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}
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}
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