do not leak file descriptors in lirc_mode2

aya/src/programs/extension.rs

@@ -1,8 +1,8 @@
 //! Extension programs.
-use std::os::fd::{AsRawFd, RawFd};
-use thiserror::Error;
+use std::os::fd::{AsFd, AsRawFd, OwnedFd};
 
 use object::Endianness;
+use thiserror::Error;
 
 use crate::{
     generated::{bpf_attach_type::BPF_CGROUP_INET_INGRESS, bpf_prog_type::BPF_PROG_TYPE_EXT},
@@ -71,11 +71,12 @@ impl Extension {
     /// There are no restrictions on what functions may be replaced, so you could replace
     /// the main entry point of your program with an extension.
     pub fn load(&mut self, program: ProgramFd, func_name: &str) -> Result<(), ProgramError> {
-        let target_prog_fd = program.as_raw_fd();
+        let target_prog_fd = program.as_fd();
         let (btf_fd, btf_id) = get_btf_info(target_prog_fd, func_name)?;
 
-        self.data.attach_btf_obj_fd = Some(btf_fd as u32);
-        self.data.attach_prog_fd = Some(target_prog_fd);
+        self.data.attach_btf_obj_fd = Some(btf_fd);
+        // TODO (AM)
+        self.data.attach_prog_fd = Some(target_prog_fd.as_raw_fd());
         self.data.attach_btf_id = Some(btf_id);
         load_program(BPF_PROG_TYPE_EXT, &mut self.data)
     }
@@ -118,11 +119,18 @@ impl Extension {
         program: ProgramFd,
         func_name: &str,
     ) -> Result<ExtensionLinkId, ProgramError> {
-        let target_fd = program.as_raw_fd();
+        let target_fd = program.as_fd();
         let (_, btf_id) = get_btf_info(target_fd, func_name)?;
         let prog_fd = self.data.fd_or_err()?;
         // the attach type must be set as 0, which is bpf_attach_type::BPF_CGROUP_INET_INGRESS
-        let link_fd = bpf_link_create(prog_fd, target_fd, BPF_CGROUP_INET_INGRESS, Some(btf_id), 0)
+        // TODO (AM)
+        let link_fd = bpf_link_create(
+            prog_fd,
+            target_fd.as_raw_fd(),
+            BPF_CGROUP_INET_INGRESS,
+            Some(btf_id),
+            0,
+        )
         .map_err(|(_, io_error)| ProgramError::SyscallError {
             call: "bpf_link_create".to_owned(),
             io_error,
@@ -151,7 +159,10 @@ impl Extension {
 
 /// Retrieves the FD of the BTF object for the provided `prog_fd` and the BTF ID of the function
 /// with the name `func_name` within that BTF object.
-fn get_btf_info(prog_fd: i32, func_name: &str) -> Result<(RawFd, u32), ProgramError> {
+fn get_btf_info(
+    prog_fd: std::os::fd::BorrowedFd<'_>,
+    func_name: &str,
+) -> Result<(OwnedFd, u32), ProgramError> {
     // retrieve program information
     let info =
         sys::bpf_prog_get_info_by_fd(prog_fd).map_err(|io_error| ProgramError::SyscallError {
@@ -174,12 +185,12 @@ fn get_btf_info(prog_fd: i32, func_name: &str) -> Result<(RawFd, u32), ProgramEr
     // we need to read the btf bytes into a buffer but we don't know the size ahead of time.
     // assume 4kb. if this is too small we can resize based on the size obtained in the response.
     let mut buf = vec![0u8; 4096];
-    let btf_info = match sys::btf_obj_get_info_by_fd(btf_fd, &mut buf) {
+    let btf_info = match sys::btf_obj_get_info_by_fd(btf_fd.as_fd(), &mut buf) {
         Ok(info) => {
             if info.btf_size > buf.len() as u32 {
                 buf.resize(info.btf_size as usize, 0u8);
                 let btf_info =
-                    sys::btf_obj_get_info_by_fd(btf_fd, &mut buf).map_err(|io_error| {
+                    sys::btf_obj_get_info_by_fd(btf_fd.as_fd(), &mut buf).map_err(|io_error| {
                         ProgramError::SyscallError {
                             call: "bpf_prog_get_info_by_fd".to_owned(),
                             io_error,

aya/src/programs/lirc_mode2.rs

@@ -71,7 +71,7 @@ impl LircMode2 {
 
         // TODO (AM)
         self.data.links.insert(LircLink::new(
-            prog_fd.as_raw_fd(),
+            prog_fd.try_clone_to_owned()?,
             lircdev_fd.try_clone_to_owned()?,
         ))
     }
@@ -104,7 +104,7 @@ impl LircMode2 {
                 io_error,
             })?;
 
-            prog_fds.push(fd as RawFd);
+            prog_fds.push(fd);
         }
 
         prog_fds
@@ -121,18 +121,18 @@ pub struct LircLinkId(RawFd, RawFd);
 #[derive(Debug)]
 /// An LircMode2 Link
 pub struct LircLink {
-    prog_fd: RawFd,
+    prog_fd: OwnedFd,
     target_fd: OwnedFd,
 }
 
 impl LircLink {
-    pub(crate) fn new(prog_fd: RawFd, target_fd: OwnedFd) -> LircLink {
+    pub(crate) fn new(prog_fd: OwnedFd, target_fd: OwnedFd) -> LircLink {
         LircLink { prog_fd, target_fd }
     }
 
     /// Get ProgramInfo from this link
     pub fn info(&self) -> Result<ProgramInfo, ProgramError> {
-        match bpf_prog_get_info_by_fd(self.prog_fd) {
+        match bpf_prog_get_info_by_fd(self.prog_fd.as_fd()) {
             Ok(info) => Ok(ProgramInfo(info)),
             Err(io_error) => Err(ProgramError::SyscallError {
                 call: "bpf_prog_get_info_by_fd".to_owned(),
@@ -147,12 +147,16 @@ impl Link for LircLink {
 
     fn id(&self) -> Self::Id {
         // TODO (AM)
-        LircLinkId(self.prog_fd, self.target_fd.as_raw_fd())
+        LircLinkId(self.prog_fd.as_raw_fd(), self.target_fd.as_raw_fd())
     }
 
     fn detach(self) -> Result<(), ProgramError> {
         // TODO (AM)
-        let _ = bpf_prog_detach(self.prog_fd, self.target_fd.as_raw_fd(), BPF_LIRC_MODE2);
+        let _ = bpf_prog_detach(
+            self.prog_fd.as_raw_fd(),
+            self.target_fd.as_raw_fd(),
+            BPF_LIRC_MODE2,
+        );
         Ok(())
     }
 }

aya/src/programs/mod.rs

@@ -418,7 +418,7 @@ pub(crate) struct ProgramData<T: Link> {
     pub(crate) fd: Option<OwnedFd>,
     pub(crate) links: LinkMap<T>,
     pub(crate) expected_attach_type: Option<bpf_attach_type>,
-    pub(crate) attach_btf_obj_fd: Option<u32>,
+    pub(crate) attach_btf_obj_fd: Option<OwnedFd>,
     pub(crate) attach_btf_id: Option<u32>,
     pub(crate) attach_prog_fd: Option<RawFd>,
     pub(crate) btf_fd: Option<RawFd>,
@@ -468,7 +468,7 @@ impl<T: Link> ProgramData<T> {
                     io_error,
                 }
             })?;
-            Some(fd as u32)
+            Some(fd)
         } else {
             None
         };
@@ -500,12 +500,10 @@ impl<T: Link> ProgramData<T> {
                 io_error,
             })?;
 
-        // TODO: AM
-        let info = bpf_prog_get_info_by_fd(fd.as_raw_fd()).map_err(|io_error| {
-            ProgramError::SyscallError {
+        let info =
+            bpf_prog_get_info_by_fd(fd.as_fd()).map_err(|io_error| ProgramError::SyscallError {
                 call: "bpf_prog_get_info_by_fd".to_owned(),
                 io_error,
-            }
             })?;
 
         let info = ProgramInfo(info);
@@ -615,7 +613,7 @@ fn load_program<T: Link>(
         kernel_version: target_kernel_version,
         expected_attach_type: data.expected_attach_type,
         prog_btf_fd: data.btf_fd,
-        attach_btf_obj_fd: data.attach_btf_obj_fd,
+        attach_btf_obj_fd: data.attach_btf_obj_fd.as_ref().map(|f| f.as_fd()),
         attach_btf_id: data.attach_btf_id,
         attach_prog_fd: data.attach_prog_fd,
         func_info_rec_size: *func_info_rec_size,
@@ -955,15 +953,13 @@ impl ProgramInfo {
     }
 
     /// Returns the fd associated with the program.
-    ///
-    /// The returned fd must be closed when no longer needed.
-    pub fn fd(&self) -> Result<RawFd, ProgramError> {
+    pub fn fd(&self) -> Result<OwnedFd, ProgramError> {
         let fd =
             bpf_prog_get_fd_by_id(self.0.id).map_err(|io_error| ProgramError::SyscallError {
                 call: "bpf_prog_get_fd_by_id".to_owned(),
                 io_error,
             })?;
-        Ok(fd as RawFd)
+        Ok(fd)
     }
 
     /// Loads a program from a pinned path in bpffs.
@@ -975,12 +971,10 @@ impl ProgramInfo {
                 io_error,
             })?;
 
-        // TODO (AM)
-        let info = bpf_prog_get_info_by_fd(fd.as_raw_fd()).map_err(|io_error| {
-            ProgramError::SyscallError {
+        let info =
+            bpf_prog_get_info_by_fd(fd.as_fd()).map_err(|io_error| ProgramError::SyscallError {
                 call: "bpf_prog_get_info_by_fd".to_owned(),
                 io_error,
-            }
             })?;
 
         Ok(ProgramInfo(info))
@@ -1012,14 +1006,12 @@ impl Iterator for ProgramsIter {
                             io_error,
                         })
                         .and_then(|fd| {
-                            let info = bpf_prog_get_info_by_fd(fd)
+                            bpf_prog_get_info_by_fd(fd.as_fd())
                                 .map_err(|io_error| ProgramError::SyscallError {
                                     call: "bpf_prog_get_info_by_fd".to_owned(),
                                     io_error,
                                 })
-                                .map(ProgramInfo);
-                            unsafe { libc::close(fd) };
-                            info
+                                .map(ProgramInfo)
                         }),
                 )
             }

aya/src/sys/bpf.rs

@@ -125,7 +125,7 @@ pub(crate) struct BpfLoadProgramAttrs<'a> {
     pub(crate) kernel_version: u32,
     pub(crate) expected_attach_type: Option<bpf_attach_type>,
     pub(crate) prog_btf_fd: Option<RawFd>,
-    pub(crate) attach_btf_obj_fd: Option<u32>,
+    pub(crate) attach_btf_obj_fd: Option<BorrowedFd<'a>>,
     pub(crate) attach_btf_id: Option<u32>,
     pub(crate) attach_prog_fd: Option<RawFd>,
     pub(crate) func_info_rec_size: usize,
@@ -189,7 +189,7 @@ pub(crate) fn bpf_load_program(
         u.log_size = log_buf.capacity() as u32;
     }
     if let Some(v) = aya_attr.attach_btf_obj_fd {
-        u.__bindgen_anon_1.attach_btf_obj_fd = v;
+        u.__bindgen_anon_1.attach_btf_obj_fd = v.as_raw_fd() as u32;
     }
     if let Some(v) = aya_attr.attach_prog_fd {
         u.__bindgen_anon_1.attach_prog_fd = v as u32;
@@ -474,23 +474,24 @@ pub(crate) fn bpf_prog_query(
     ret
 }
 
-pub(crate) fn bpf_prog_get_fd_by_id(prog_id: u32) -> io::Result<RawFd> {
+pub(crate) fn bpf_prog_get_fd_by_id(prog_id: u32) -> io::Result<OwnedFd> {
     let mut attr = unsafe { mem::zeroed::<bpf_attr>() };
 
     attr.__bindgen_anon_6.__bindgen_anon_1.prog_id = prog_id;
 
     match sys_bpf(bpf_cmd::BPF_PROG_GET_FD_BY_ID, &attr) {
-        Ok(v) => Ok(v as RawFd),
+        // SAFETY: BPF_PROG_GET_FD_BY_ID returns new fd
+        Ok(v) => Ok(unsafe { OwnedFd::from_raw_fd(v as RawFd) }),
         Err((_, err)) => Err(err),
     }
 }
 
-pub(crate) fn bpf_prog_get_info_by_fd(prog_fd: RawFd) -> io::Result<bpf_prog_info> {
+pub(crate) fn bpf_prog_get_info_by_fd(prog_fd: BorrowedFd<'_>) -> io::Result<bpf_prog_info> {
     let mut attr = unsafe { mem::zeroed::<bpf_attr>() };
     // info gets entirely populated by the kernel
     let info = MaybeUninit::zeroed();
 
-    attr.info.bpf_fd = prog_fd as u32;
+    attr.info.bpf_fd = prog_fd.as_raw_fd() as u32;
     attr.info.info = &info as *const _ as u64;
     attr.info.info_len = mem::size_of::<bpf_prog_info>() as u32;
 
@@ -530,13 +531,16 @@ pub(crate) fn bpf_link_get_info_by_fd(link_fd: BorrowedFd<'_>) -> io::Result<bpf
     }
 }
 
-pub(crate) fn btf_obj_get_info_by_fd(prog_fd: RawFd, buf: &mut [u8]) -> io::Result<bpf_btf_info> {
+pub(crate) fn btf_obj_get_info_by_fd(
+    prog_fd: BorrowedFd<'_>,
+    buf: &mut [u8],
+) -> io::Result<bpf_btf_info> {
     let mut attr = unsafe { mem::zeroed::<bpf_attr>() };
     let mut info = unsafe { mem::zeroed::<bpf_btf_info>() };
     let buf_size = buf.len() as u32;
     info.btf = buf.as_ptr() as u64;
     info.btf_size = buf_size;
-    attr.info.bpf_fd = prog_fd as u32;
+    attr.info.bpf_fd = prog_fd.as_raw_fd() as u32;
     attr.info.info = &info as *const bpf_btf_info as u64;
     attr.info.info_len = mem::size_of::<bpf_btf_info>() as u32;
 
@@ -579,12 +583,13 @@ pub(crate) fn bpf_load_btf(raw_btf: &[u8], log: &mut VerifierLog) -> Result<Owne
     Ok(unsafe { OwnedFd::from_raw_fd(fd) })
 }
 
-pub(crate) fn bpf_btf_get_fd_by_id(id: u32) -> io::Result<RawFd> {
+pub(crate) fn bpf_btf_get_fd_by_id(id: u32) -> io::Result<OwnedFd> {
     let mut attr = unsafe { mem::zeroed::<bpf_attr>() };
     attr.__bindgen_anon_6.__bindgen_anon_1.btf_id = id;
 
     match sys_bpf(bpf_cmd::BPF_BTF_GET_FD_BY_ID, &attr) {
-        Ok(v) => Ok(v as RawFd),
+        // SAFETY: BPF_BTF_GET_FD_BY_ID returns new fd
+        Ok(v) => Ok(unsafe { OwnedFd::from_raw_fd(v as RawFd) }),
         Err((_, err)) => Err(err),
     }
 }