lsm :: cgroup attachment type support

Cargo.toml

@@ -78,7 +78,7 @@ indoc = { version = "2.0", default-features = false }
 libc = { version = "0.2.105", default-features = false }
 log = { version = "0.4", default-features = false }
 netns-rs = { version = "0.1", default-features = false }
-nix = { version = "0.29.0", default-features = false }
+nix = { version = "0.29.0", default-features = true }
 num_enum = { version = "0.7", default-features = false }
 object = { version = "0.36", default-features = false }
 octorust = { version = "0.9.0", default-features = false }

aya-ebpf-macros/src/lib.rs

@@ -10,6 +10,7 @@ mod fentry;
 mod fexit;
 mod kprobe;
 mod lsm;
+mod lsm_cgroup;
 mod map;
 mod perf_event;
 mod raw_tracepoint;
@@ -34,6 +35,7 @@ use fentry::FEntry;
 use fexit::FExit;
 use kprobe::{KProbe, KProbeKind};
 use lsm::Lsm;
+use lsm_cgroup::LsmCgroup;
 use map::Map;
 use perf_event::PerfEvent;
 use proc_macro::TokenStream;
@@ -326,6 +328,49 @@ pub fn lsm(attrs: TokenStream, item: TokenStream) -> TokenStream {
     .into()
 }
 
+/// Marks a function as an LSM program that can be attached to cgroups.
+/// This program will only trigger for workloads in the attached cgroups.
+/// Used to implement security policy and audit logging.
+///
+/// The hook name is the first and only argument to the macro.
+///
+/// LSM probes can be attached to the kernel's security hooks to implement mandatory
+/// access control policy and security auditing.
+///
+/// LSM probes require a kernel compiled with `CONFIG_BPF_LSM=y` and `CONFIG_DEBUG_INFO_BTF=y`.
+/// In order for the probes to fire, you also need the BPF LSM to be enabled through your
+/// kernel's boot paramters (like `lsm=lockdown,yama,bpf`).
+///
+/// # Minimum kernel version
+///
+/// The minimum kernel version required to use this feature is 6.0.
+///
+/// # Examples
+///
+/// ```no_run
+/// use aya_ebpf::{macros::lsm_cgroup, programs::LsmContext};
+///
+/// #[lsm_cgroup(hook = "file_open")]
+/// pub fn file_open(ctx: LsmContext) -> i32 {
+///     match unsafe { try_file_open(ctx) } {
+///         Ok(ret) => ret,
+///         Err(ret) => ret,
+///     }
+/// }
+///
+/// unsafe fn try_file_open(_ctx: LsmContext) -> Result<i32, i32> {
+///     Err(0)
+/// }
+/// ```
+#[proc_macro_attribute]
+pub fn lsm_cgroup(attrs: TokenStream, item: TokenStream) -> TokenStream {
+    match LsmCgroup::parse(attrs.into(), item.into()) {
+        Ok(prog) => prog.expand(),
+        Err(err) => err.into_compile_error(),
+    }
+    .into()
+}
+
 /// Marks a function as a [BTF-enabled raw tracepoint][1] eBPF program that can be attached at
 /// a pre-defined kernel trace point.
 ///

aya-ebpf-macros/src/lsm.rs

@@ -19,6 +19,7 @@ impl Lsm {
         let hook = pop_string_arg(&mut args, "hook");
         let sleepable = pop_bool_arg(&mut args, "sleepable");
         err_on_unknown_args(&args)?;
+
         Ok(Self {
             item,
             hook,
@@ -39,15 +40,15 @@ impl Lsm {
             block: _,
         } = item;
         let section_prefix = if *sleepable { "lsm.s" } else { "lsm" };
-        let section_name: Cow<'_, _> = if let Some(hook) = hook {
-            format!("{}/{}", section_prefix, hook).into()
+        let section_name: Cow<'_, _> = if let Some(name) = hook {
+            format!("{}/{}", section_prefix, name).into()
         } else {
             section_prefix.into()
         };
+        let fn_name = &sig.ident;
         // LSM probes need to return an integer corresponding to the correct
         // policy decision. Therefore we do not simply default to a return value
         // of 0 as in other program types.
-        let fn_name = &sig.ident;
         quote! {
             #[no_mangle]
             #[link_section = #section_name]

aya-ebpf-macros/src/lsm_cgroup.rs

@@ -0,0 +1,87 @@
+use std::borrow::Cow;
+
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{ItemFn, Result};
+
+use crate::args::{err_on_unknown_args, pop_string_arg};
+
+pub(crate) struct LsmCgroup {
+    item: ItemFn,
+    hook: Option<String>,
+}
+
+impl LsmCgroup {
+    pub(crate) fn parse(attrs: TokenStream, item: TokenStream) -> Result<Self> {
+        let item = syn::parse2(item)?;
+        let mut args = syn::parse2(attrs)?;
+        let hook = pop_string_arg(&mut args, "hook");
+        err_on_unknown_args(&args)?;
+
+        Ok(Self { item, hook })
+    }
+
+    pub(crate) fn expand(&self) -> TokenStream {
+        let Self { item, hook } = self;
+        let ItemFn {
+            attrs: _,
+            vis,
+            sig,
+            block: _,
+        } = item;
+        let section_prefix = "lsm_cgroup";
+        let section_name: Cow<'_, _> = if let Some(name) = hook {
+            format!("{}/{}", section_prefix, name).into()
+        } else {
+            section_prefix.into()
+        };
+        let fn_name = &sig.ident;
+        // LSM probes need to return an integer corresponding to the correct
+        // policy decision. Therefore we do not simply default to a return value
+        // of 0 as in other program types.
+        quote! {
+            #[no_mangle]
+            #[link_section = #section_name]
+            #vis fn #fn_name(ctx: *mut ::core::ffi::c_void) -> i32 {
+                return #fn_name(::aya_ebpf::programs::LsmContext::new(ctx));
+
+                #item
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use syn::parse_quote;
+
+    use super::*;
+
+    #[test]
+    fn test_lsm_cgroup() {
+        let prog = LsmCgroup::parse(
+            parse_quote! {
+                hook = "bprm_committed_creds",
+            },
+            parse_quote! {
+                fn bprm_committed_creds(ctx: &mut ::aya_ebpf::programs::LsmContext) -> i32 {
+                    0
+                }
+            },
+        )
+        .unwrap();
+        let expanded = prog.expand();
+        let expected = quote! {
+            #[no_mangle]
+            #[link_section = "lsm_cgroup/bprm_committed_creds"]
+            fn bprm_committed_creds(ctx: *mut ::core::ffi::c_void) -> i32 {
+                return bprm_committed_creds(::aya_ebpf::programs::LsmContext::new(ctx));
+
+                fn bprm_committed_creds(ctx: &mut ::aya_ebpf::programs::LsmContext) -> i32 {
+                    0
+                }
+            }
+        };
+        assert_eq!(expected.to_string(), expanded.to_string());
+    }
+}

aya-obj/src/obj.rs

@@ -27,7 +27,8 @@ use crate::{
     },
     maps::{bpf_map_def, BtfMap, BtfMapDef, LegacyMap, Map, PinningType, MINIMUM_MAP_SIZE},
     programs::{
-        CgroupSockAddrAttachType, CgroupSockAttachType, CgroupSockoptAttachType, XdpAttachType,
+        CgroupSockAddrAttachType, CgroupSockAttachType, CgroupSockoptAttachType, LsmAttachType,
+        XdpAttachType,
     },
     relocation::*,
     util::HashMap,
@@ -274,6 +275,10 @@ pub enum ProgramSection {
     RawTracePoint,
     Lsm {
         sleepable: bool,
+        attach_type: LsmAttachType,
+    },
+    LsmCgroup {
+        attach_type: LsmAttachType,
     },
     BtfTracePoint,
     FEntry {
@@ -434,8 +439,17 @@ impl FromStr for ProgramSection {
             "lirc_mode2" => LircMode2,
             "perf_event" => PerfEvent,
             "raw_tp" | "raw_tracepoint" => RawTracePoint,
-            "lsm" => Lsm { sleepable: false },
-            "lsm.s" => Lsm { sleepable: true },
+            "lsm" => Lsm {
+                sleepable: false,
+                attach_type: LsmAttachType::Mac,
+            },
+            "lsm.s" => Lsm {
+                sleepable: true,
+                attach_type: LsmAttachType::Mac,
+            },
+            "lsm_cgroup" => LsmCgroup {
+                attach_type: LsmAttachType::Cgroup,
+            },
             "fentry" => FEntry { sleepable: false },
             "fentry.s" => FEntry { sleepable: true },
             "fexit" => FExit { sleepable: false },
@@ -2190,7 +2204,7 @@ mod tests {
             Some(Program {
                 section: ProgramSection::Lsm {
                     sleepable: false,
-                    ..
+                    attach_type: LsmAttachType::Mac
                 },
                 ..
             })
@@ -2223,6 +2237,31 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_parse_section_lsm_cgroup() {
+        let mut obj = fake_obj();
+        fake_sym(&mut obj, 0, 0, "foo", FAKE_INS_LEN);
+
+        assert_matches!(
+            obj.parse_section(fake_section(
+                EbpfSectionKind::Program,
+                "lsm_cgroup/foo",
+                bytes_of(&fake_ins()),
+                None
+            )),
+            Ok(())
+        );
+        assert_matches!(
+            obj.programs.get("foo"),
+            Some(Program {
+                section: ProgramSection::LsmCgroup {
+                    attach_type: LsmAttachType::Cgroup,
+                },
+                ..
+            })
+        );
+    }
+
     #[test]
     fn test_parse_section_btf_tracepoint() {
         let mut obj = fake_obj();

aya-obj/src/programs/lsm.rs

@@ -0,0 +1,21 @@
+//! XDP programs.
+
+use crate::generated::bpf_attach_type;
+
+/// Defines where to attach an `XDP` program.
+#[derive(Copy, Clone, Debug)]
+pub enum LsmAttachType {
+    /// Cgroup based LSM program
+    Cgroup,
+    /// MAC based LSM program
+    Mac,
+}
+
+impl From<LsmAttachType> for bpf_attach_type {
+    fn from(value: LsmAttachType) -> Self {
+        match value {
+            LsmAttachType::Cgroup => bpf_attach_type::BPF_LSM_CGROUP,
+            LsmAttachType::Mac => bpf_attach_type::BPF_LSM_MAC,
+        }
+    }
+}

aya-obj/src/programs/mod.rs

@@ -3,10 +3,12 @@
 pub mod cgroup_sock;
 pub mod cgroup_sock_addr;
 pub mod cgroup_sockopt;
+pub mod lsm;
 mod types;
 pub mod xdp;
 
 pub use cgroup_sock::CgroupSockAttachType;
 pub use cgroup_sock_addr::CgroupSockAddrAttachType;
 pub use cgroup_sockopt::CgroupSockoptAttachType;
+pub use lsm::LsmAttachType;
 pub use xdp::XdpAttachType;

aya/src/bpf.rs

@@ -30,8 +30,9 @@ use crate::{
     programs::{
         BtfTracePoint, CgroupDevice, CgroupSkb, CgroupSkbAttachType, CgroupSock, CgroupSockAddr,
         CgroupSockopt, CgroupSysctl, Extension, FEntry, FExit, Iter, KProbe, LircMode2, Lsm,
-        PerfEvent, ProbeKind, Program, ProgramData, ProgramError, RawTracePoint, SchedClassifier,
-        SkLookup, SkMsg, SkSkb, SkSkbKind, SockOps, SocketFilter, TracePoint, UProbe, Xdp,
+        LsmCgroup, PerfEvent, ProbeKind, Program, ProgramData, ProgramError, RawTracePoint,
+        SchedClassifier, SkLookup, SkMsg, SkSkb, SkSkbKind, SockOps, SocketFilter, TracePoint,
+        UProbe, Xdp,
     },
     sys::{
         bpf_load_btf, is_bpf_cookie_supported, is_bpf_global_data_supported,
@@ -411,7 +412,11 @@ impl<'a> EbpfLoader<'a> {
                                 ProgramSection::Extension
                                 | ProgramSection::FEntry { sleepable: _ }
                                 | ProgramSection::FExit { sleepable: _ }
-                                | ProgramSection::Lsm { sleepable: _ }
+                                | ProgramSection::Lsm {
+                                    sleepable: _,
+                                    attach_type: _,
+                                }
+                                | ProgramSection::LsmCgroup { attach_type: _ }
                                 | ProgramSection::BtfTracePoint
                                 | ProgramSection::Iter { sleepable: _ } => {
                                     return Err(EbpfError::BtfError(err))
@@ -649,13 +654,25 @@ impl<'a> EbpfLoader<'a> {
                         ProgramSection::RawTracePoint => Program::RawTracePoint(RawTracePoint {
                             data: ProgramData::new(prog_name, obj, btf_fd, *verifier_log_level),
                         }),
-                        ProgramSection::Lsm { sleepable } => {
+                        ProgramSection::Lsm {
+                            sleepable,
+                            attach_type,
+                        } => {
                             let mut data =
                                 ProgramData::new(prog_name, obj, btf_fd, *verifier_log_level);
                             if *sleepable {
                                 data.flags = BPF_F_SLEEPABLE;
                             }
-                            Program::Lsm(Lsm { data })
+                            Program::Lsm(Lsm {
+                                data,
+                                attach_type: *attach_type,
+                            })
+                        }
+                        ProgramSection::LsmCgroup { attach_type } => {
+                            Program::LsmCgroup(LsmCgroup {
+                                data: ProgramData::new(prog_name, obj, btf_fd, *verifier_log_level),
+                                attach_type: *attach_type,
+                            })
                         }
                         ProgramSection::BtfTracePoint => Program::BtfTracePoint(BtfTracePoint {
                             data: ProgramData::new(prog_name, obj, btf_fd, *verifier_log_level),