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143 lines
4.5 KiB
Rust
143 lines
4.5 KiB
Rust
use core::{cell::UnsafeCell, mem, num::NonZeroU32};
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use aya_ebpf_bindings::bindings::bpf_devmap_val;
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use super::{dev_map::DevMapValue, try_redirect_map};
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use crate::{
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bindings::{bpf_map_def, bpf_map_type::BPF_MAP_TYPE_DEVMAP_HASH},
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lookup,
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maps::PinningType,
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};
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/// A map of network devices.
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///
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/// XDP programs can use this map to redirect packets to other network devices. It is similar to
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/// [`DevMap`](super::DevMap), but is an hash map rather than an array. Keys do not need to be
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/// contiguous nor start at zero, but there is a hashing cost to every lookup.
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///
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/// # Minimum kernel version
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///
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/// The minimum kernel version required to use this feature is 5.4.
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///
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/// # Examples
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///
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/// ```rust,no_run
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/// use aya_ebpf::{bindings::xdp_action, macros::{map, xdp}, maps::DevMapHash, programs::XdpContext};
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///
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/// #[map]
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/// static MAP: DevMapHash = DevMapHash::with_max_entries(1, 0);
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///
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/// #[xdp]
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/// fn xdp(_ctx: XdpContext) -> u32 {
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/// MAP.redirect(42, xdp_action::XDP_PASS as u64).unwrap_or(xdp_action::XDP_DROP)
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/// }
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/// ```
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#[repr(transparent)]
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pub struct DevMapHash {
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def: UnsafeCell<bpf_map_def>,
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}
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unsafe impl Sync for DevMapHash {}
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impl DevMapHash {
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/// Creates a [`DevMapHash`] with a set maximum number of elements.
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///
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/// # Examples
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///
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/// ```rust,no_run
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/// use aya_ebpf::{macros::map, maps::DevMapHash};
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///
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/// #[map]
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/// static MAP: DevMapHash = DevMapHash::with_max_entries(8, 0);
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/// ```
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pub const fn with_max_entries(max_entries: u32, flags: u32) -> DevMapHash {
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DevMapHash {
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def: UnsafeCell::new(bpf_map_def {
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type_: BPF_MAP_TYPE_DEVMAP_HASH,
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key_size: mem::size_of::<u32>() as u32,
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value_size: mem::size_of::<bpf_devmap_val>() as u32,
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max_entries,
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map_flags: flags,
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id: 0,
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pinning: PinningType::None as u32,
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}),
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}
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}
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/// Creates a [`DevMapHash`] with a set maximum number of elements that can be pinned to the BPF
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/// File System (bpffs).
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///
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/// # Examples
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///
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/// ```rust,no_run
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/// use aya_ebpf::{macros::map, maps::DevMapHash};
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///
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/// #[map]
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/// static MAP: DevMapHash = DevMapHash::pinned(8, 0);
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/// ```
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pub const fn pinned(max_entries: u32, flags: u32) -> DevMapHash {
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DevMapHash {
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def: UnsafeCell::new(bpf_map_def {
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type_: BPF_MAP_TYPE_DEVMAP_HASH,
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key_size: mem::size_of::<u32>() as u32,
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value_size: mem::size_of::<bpf_devmap_val>() as u32,
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max_entries,
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map_flags: flags,
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id: 0,
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pinning: PinningType::ByName as u32,
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}),
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}
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}
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/// Retrieves the interface index with `key` in the map.
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///
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/// To actually redirect a packet, see [`DevMapHash::redirect`].
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///
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/// # Examples
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///
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/// ```rust,no_run
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/// use aya_ebpf::{macros::map, maps::DevMapHash};
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///
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/// #[map]
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/// static MAP: DevMapHash = DevMapHash::with_max_entries(1, 0);
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///
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/// let target_if_index = MAP.get(42).unwrap().if_index;
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///
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/// // redirect to ifindex
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/// ```
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#[inline(always)]
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pub fn get(&self, key: u32) -> Option<DevMapValue> {
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let value = lookup(self.def.get(), &key)?;
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let value: &bpf_devmap_val = unsafe { value.as_ref() };
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Some(DevMapValue {
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if_index: value.ifindex,
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// SAFETY: map writes use fd, map reads use id.
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// https://elixir.bootlin.com/linux/v6.2/source/include/uapi/linux/bpf.h#L6136
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prog_id: NonZeroU32::new(unsafe { value.bpf_prog.id }),
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})
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}
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/// Redirects the current packet on the interface at `key`.
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///
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/// The lower two bits of `flags` are used for the return code if the map lookup fails, which
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/// can be used as the XDP program's return code if a CPU cannot be found.
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///
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/// # Examples
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///
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/// ```rust,no_run
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/// use aya_ebpf::{bindings::xdp_action, macros::{map, xdp}, maps::DevMapHash, programs::XdpContext};
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///
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/// #[map]
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/// static MAP: DevMapHash = DevMapHash::with_max_entries(8, 0);
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///
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/// #[xdp]
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/// fn xdp(_ctx: XdpContext) -> u32 {
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/// MAP.redirect(7, 0).unwrap_or(xdp_action::XDP_DROP)
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/// }
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/// ```
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#[inline(always)]
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pub fn redirect(&self, key: u32, flags: u64) -> Result<u32, u32> {
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try_redirect_map(&self.def, key, flags)
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}
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}
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