Skip to content

Commit

Permalink
ebpf: Add TcContext for classifier programs
Browse files Browse the repository at this point in the history 
This change separates the previous `SkBuffContext` into three structs:

* `SkBuff` which is a wrapper around `__sk_buff` which contains all
  possible methods operating on it.
* `SkBuffContext` which is a program context for programs which
  **cannot** access `__sk_buff` directly and instead can only use
  `load_bytes`.
* `TcContext` which is a classifier context which can access `__sk_buff`
  directly, hence exposes `data` and `data_end`.

Signed-off-by: Michal Rostecki <[email protected]>
  • Loading branch information
@vadorovsky
vadorovsky committed Sep 6, 2022
1 parent 9451699 commit 895f96e
Show file tree
Hide file tree
Showing 4 changed files with 359 additions and 50 deletions.
2 changes: 1 addition & 1 deletion aya-bpf-macros/src/expand.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -250,7 +250,7 @@ impl SchedClassifier {
#[no_mangle]
#[link_section = #section_name]
fn #fn_name(ctx: *mut ::aya_bpf::bindings::__sk_buff) -> i32 {
return #fn_name(::aya_bpf::programs::SkBuffContext::new(ctx));
return #fn_name(::aya_bpf::programs::TcContext::new(ctx));

#item
}
Expand Down
2 changes: 2 additions & 0 deletions bpf/aya-bpf/src/programs/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ pub mod sock_addr;
pub mod sock_ops;
pub mod sockopt;
pub mod sysctl;
pub mod tc;
pub mod tp_btf;
pub mod tracepoint;
pub mod xdp;
Expand All @@ -30,6 +31,7 @@ pub use sock_addr::SockAddrContext;
pub use sock_ops::SockOpsContext;
pub use sockopt::SockoptContext;
pub use sysctl::SysctlContext;
pub use tc::TcContext;
pub use tp_btf::BtfTracePointContext;
pub use tracepoint::TracePointContext;
pub use xdp::XdpContext;
221 changes: 172 additions & 49 deletions bpf/aya-bpf/src/programs/sk_buff.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,13 +13,13 @@ use aya_bpf_cty::c_long;

use crate::{bindings::__sk_buff, BpfContext};

pub struct SkBuffContext {
pub struct SkBuff {
pub skb: *mut __sk_buff,
}

impl SkBuffContext {
pub fn new(skb: *mut __sk_buff) -> SkBuffContext {
SkBuffContext { skb }
impl SkBuff {
pub fn new(skb: *mut __sk_buff) -> SkBuff {
SkBuff { skb }
}

#[allow(clippy::len_without_is_empty)]
Expand All @@ -28,6 +28,16 @@ impl SkBuffContext {
unsafe { *self.skb }.len
}

#[inline]
pub(crate) fn data(&self) -> usize {
unsafe { (*self.skb).data as usize }
}

#[inline]
pub(crate) fn data_end(&self) -> usize {
unsafe { (*self.skb).data_end as usize }
}

#[inline]
pub fn set_mark(&mut self, mark: u32) {
unsafe { *self.skb }.mark = mark;
Expand Down Expand Up @@ -76,43 +86,6 @@ impl SkBuffContext {
/// # Examples
///
/// Read into a `PerCpuArray`.
///
/// ```no_run
/// use core::mem;
///
/// use aya_bpf::{bindings::TC_ACT_PIPE, macros::map, maps::PerCpuArray, programs::SkBuffContext};
/// # #[allow(non_camel_case_types)]
/// # struct ethhdr {};
/// # #[allow(non_camel_case_types)]
/// # struct iphdr {};
/// # #[allow(non_camel_case_types)]
/// # struct tcphdr {};
///
/// const ETH_HDR_LEN: usize = mem::size_of::<ethhdr>();
/// const IP_HDR_LEN: usize = mem::size_of::<iphdr>();
/// const TCP_HDR_LEN: usize = mem::size_of::<tcphdr>();
///
/// #[repr(C)]
/// pub struct Buf {
/// pub buf: [u8; 1500],
/// }
///
/// #[map]
/// pub static mut BUF: PerCpuArray<Buf> = PerCpuArray::with_max_entries(1, 0);
///
/// fn try_classifier(ctx: SkBuffContext) -> Result<i32, i32> {
/// let buf = unsafe {
/// let ptr = BUF.get_ptr_mut(0).ok_or(TC_ACT_PIPE)?;
/// &mut *ptr
/// };
/// let offset = ETH_HDR_LEN + IP_HDR_LEN + TCP_HDR_LEN;
/// ctx.load_bytes(offset, &mut buf.buf).map_err(|_| TC_ACT_PIPE)?;
///
/// // do something with `buf`
///
/// Ok(TC_ACT_PIPE)
/// }
/// ```
#[inline(always)]
pub fn load_bytes(&self, offset: usize, dst: &mut [u8]) -> Result<usize, c_long> {
if offset >= self.len() as usize {
Expand Down Expand Up @@ -226,6 +199,161 @@ impl SkBuffContext {
}
}

/// Pulls in non-linear data in case the skb is non-linear.
///
/// Make len bytes from skb readable and writable. If a zero value is passed for
/// `len`, then the whole length of the skb is pulled. This helper is only needed
/// for reading and writing with direct packet access.
#[inline(always)]
pub fn pull_data(&self, len: u32) -> Result<(), c_long> {
let ret = unsafe { bpf_skb_pull_data(self.as_ptr() as *mut _, len) };
if ret == 0 {
Ok(())
} else {
Err(ret)
}
}

pub(crate) fn as_ptr(&self) -> *mut c_void {
self.skb as *mut _
}
}

pub struct SkBuffContext {
pub skb: SkBuff,
}

impl SkBuffContext {
pub fn new(skb: *mut __sk_buff) -> SkBuffContext {
let skb = SkBuff { skb };
SkBuffContext { skb }
}

#[allow(clippy::len_without_is_empty)]
#[inline]
pub fn len(&self) -> u32 {
self.skb.len()
}

#[inline]
pub fn set_mark(&mut self, mark: u32) {
self.skb.set_mark(mark)
}

#[inline]
pub fn cb(&self) -> &[u32] {
self.skb.cb()
}

#[inline]
pub fn cb_mut(&mut self) -> &mut [u32] {
self.skb.cb_mut()
}

/// Returns the owner UID of the socket associated to the SKB context.
#[inline]
pub fn get_socket_uid(&self) -> u32 {
self.skb.get_socket_uid()
}

#[inline]
pub fn load<T>(&self, offset: usize) -> Result<T, c_long> {
self.skb.load(offset)
}

/// Reads some bytes from the packet into the specified buffer, returning
/// how many bytes were read.
///
/// Starts reading at `offset` and reads at most `dst.len()` or
/// `self.len() - offset` bytes, depending on which one is smaller.
///
/// # Examples
///
/// Read into a `PerCpuArray`.
///
/// ```no_run
/// use core::mem;
///
/// use aya_bpf::{bindings::TC_ACT_PIPE, macros::map, maps::PerCpuArray, programs::SkBuffContext};
/// # #[allow(non_camel_case_types)]
/// # struct ethhdr {};
/// # #[allow(non_camel_case_types)]
/// # struct iphdr {};
/// # #[allow(non_camel_case_types)]
/// # struct tcphdr {};
///
/// const ETH_HDR_LEN: usize = mem::size_of::<ethhdr>();
/// const IP_HDR_LEN: usize = mem::size_of::<iphdr>();
/// const TCP_HDR_LEN: usize = mem::size_of::<tcphdr>();
///
/// #[repr(C)]
/// pub struct Buf {
/// pub buf: [u8; 1500],
/// }
///
/// #[map]
/// pub static mut BUF: PerCpuArray<Buf> = PerCpuArray::with_max_entries(1, 0);
///
/// fn try_cgroup_skb(ctx: SkBuffContext) -> Result<i32, i32> {
/// let buf = unsafe {
/// let ptr = BUF.get_ptr_mut(0).ok_or(TC_ACT_PIPE)?;
/// &mut *ptr
/// };
/// let offset = ETH_HDR_LEN + IP_HDR_LEN + TCP_HDR_LEN;
/// ctx.load_bytes(offset, &mut buf.buf).map_err(|_| TC_ACT_PIPE)?;
///
/// // do something with `buf`
///
/// Ok(TC_ACT_PIPE)
/// }
/// ```
#[inline(always)]
pub fn load_bytes(&self, offset: usize, dst: &mut [u8]) -> Result<usize, c_long> {
self.skb.load_bytes(offset, dst)
}

#[inline]
pub fn store<T>(&mut self, offset: usize, v: &T, flags: u64) -> Result<(), c_long> {
self.skb.store(offset, v, flags)
}

#[inline]
pub fn l3_csum_replace(
&self,
offset: usize,
from: u64,
to: u64,
size: u64,
) -> Result<(), c_long> {
self.skb.l3_csum_replace(offset, from, to, size)
}

#[inline]
pub fn l4_csum_replace(
&self,
offset: usize,
from: u64,
to: u64,
flags: u64,
) -> Result<(), c_long> {
self.skb.l4_csum_replace(offset, from, to, flags)
}

#[inline]
pub fn adjust_room(&self, len_diff: i32, mode: u32, flags: u64) -> Result<(), c_long> {
self.skb.adjust_room(len_diff, mode, flags)
}

#[inline]
pub fn clone_redirect(&self, if_index: u32, flags: u64) -> Result<(), c_long> {
self.skb.clone_redirect(if_index, flags)
}

#[inline]
pub fn change_type(&self, ty: u32) -> Result<(), c_long> {
self.skb.change_type(ty)
}

/// Pulls in non-linear data in case the skb is non-linear.
///
/// Make len bytes from skb readable and writable. If a zero value is passed for
Expand All @@ -242,7 +370,7 @@ impl SkBuffContext {
/// const IP_HLEN: usize = core::mem::size_of::<iphdr>();
/// const UDP_HLEN: usize = core::mem::size_of::<udphdr>();
///
/// fn try_classifier(ctx: SkBuffContext) -> Result<i32, i32> {
/// fn try_cgroup_skb(ctx: SkBuffContext) -> Result<i32, i32> {
/// let len = ETH_HLEN + IP_HLEN + UDP_HLEN;
/// match ctx.pull_data(len as u32) {
/// Ok(_) => return Ok(0),
Expand All @@ -252,17 +380,12 @@ impl SkBuffContext {
/// ```
#[inline(always)]
pub fn pull_data(&self, len: u32) -> Result<(), c_long> {
let ret = unsafe { bpf_skb_pull_data(self.as_ptr() as *mut _, len) };
if ret == 0 {
Ok(())
} else {
Err(ret)
}
self.skb.pull_data(len)
}
}

impl BpfContext for SkBuffContext {
fn as_ptr(&self) -> *mut c_void {
self.skb as *mut _
self.skb.as_ptr()
}
}
Loading

0 comments on commit 895f96e

Please sign in to comment.