programs: ProgramFd is owned

`ProgramData::fd` is now a `ProgramFd`. This means that `ProgramData`
now closes the file descriptor on drop. In the future we might consider
making `ProgramFd` hold a `BorrowedFd` but this requires API design work
due to overlapping borrows.

Since `ProgramFd` is no longer `Copy`, update methods to take it by
reference to allow callers to use it multiple times as they are
accustomed to doing.

`ProgramFd` is now returned by reference and implements `try_clone` to
allow callers to avoid file descriptor cloning when desired.

This is an API breaking change.

Updates #612.

aya/src/maps/array/program_array.rs

@@ -2,7 +2,7 @@
 
 use std::{
     borrow::{Borrow, BorrowMut},
-    os::fd::{AsRawFd, RawFd},
+    os::fd::{AsFd as _, AsRawFd as _, RawFd},
 };
 
 use crate::{
@@ -37,13 +37,13 @@ use crate::{
 /// let flags = 0;
 ///
 /// // bpf_tail_call(ctx, JUMP_TABLE, 0) will jump to prog_0
-/// prog_array.set(0, prog_0_fd, flags);
+/// prog_array.set(0, &prog_0_fd, flags);
 ///
 /// // bpf_tail_call(ctx, JUMP_TABLE, 1) will jump to prog_1
-/// prog_array.set(1, prog_1_fd, flags);
+/// prog_array.set(1, &prog_1_fd, flags);
 ///
 /// // bpf_tail_call(ctx, JUMP_TABLE, 2) will jump to prog_2
-/// prog_array.set(2, prog_2_fd, flags);
+/// prog_array.set(2, &prog_2_fd, flags);
 /// # Ok::<(), aya::BpfError>(())
 /// ```
 #[doc(alias = "BPF_MAP_TYPE_PROG_ARRAY")]
@@ -73,11 +73,12 @@ impl<T: BorrowMut<MapData>> ProgramArray<T> {
     ///
     /// When an eBPF program calls `bpf_tail_call(ctx, prog_array, index)`, control
     /// flow will jump to `program`.
-    pub fn set(&mut self, index: u32, program: ProgramFd, flags: u64) -> Result<(), MapError> {
+    pub fn set(&mut self, index: u32, program: &ProgramFd, flags: u64) -> Result<(), MapError> {
         let data = self.inner.borrow_mut();
         check_bounds(data, index)?;
         let fd = data.fd_or_err()?;
-        let prog_fd = program.as_raw_fd();
+        let prog_fd = program.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
 
         bpf_map_update_elem(fd, Some(&index), &prog_fd, flags).map_err(|(_, io_error)| {
             SyscallError {

aya/src/maps/perf/async_perf_event_array.rs

@@ -1,7 +1,7 @@
 use bytes::BytesMut;
 use std::{
     borrow::{Borrow, BorrowMut},
-    os::fd::{AsRawFd, RawFd},
+    os::fd::{AsRawFd as _, RawFd},
 };
 
 // See https://doc.rust-lang.org/cargo/reference/features.html#mutually-exclusive-features.

aya/src/programs/cgroup_device.rs

@@ -1,7 +1,7 @@
 //! Cgroup device programs.
 
 use crate::util::KernelVersion;
-use std::os::fd::AsRawFd;
+use std::os::fd::{AsFd as _, AsRawFd};
 
 use crate::{
     generated::{bpf_attach_type::BPF_CGROUP_DEVICE, bpf_prog_type::BPF_PROG_TYPE_CGROUP_DEVICE},
@@ -61,7 +61,9 @@ impl CgroupDevice {
     ///
     /// The returned value can be used to detach, see [CgroupDevice::detach]
     pub fn attach<T: AsRawFd>(&mut self, cgroup: T) -> Result<CgroupDeviceLinkId, ProgramError> {
-        let prog_fd = self.data.fd_or_err()?;
+        let prog_fd = self.fd()?;
+        let prog_fd = prog_fd.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
         let cgroup_fd = cgroup.as_raw_fd();
 
         if KernelVersion::current().unwrap() >= KernelVersion::new(5, 7, 0) {

aya/src/programs/cgroup_skb.rs

@@ -1,7 +1,11 @@
 //! Cgroup skb programs.
 
 use crate::util::KernelVersion;
-use std::{hash::Hash, os::fd::AsRawFd, path::Path};
+use std::{
+    hash::Hash,
+    os::fd::{AsFd as _, AsRawFd},
+    path::Path,
+};
 
 use crate::{
     generated::{
@@ -88,7 +92,9 @@ impl CgroupSkb {
         cgroup: T,
         attach_type: CgroupSkbAttachType,
     ) -> Result<CgroupSkbLinkId, ProgramError> {
-        let prog_fd = self.data.fd_or_err()?;
+        let prog_fd = self.fd()?;
+        let prog_fd = prog_fd.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
         let cgroup_fd = cgroup.as_raw_fd();
 
         let attach_type = match attach_type {

aya/src/programs/cgroup_sock.rs

@@ -3,7 +3,11 @@
 pub use aya_obj::programs::CgroupSockAttachType;
 
 use crate::util::KernelVersion;
-use std::{hash::Hash, os::fd::AsRawFd, path::Path};
+use std::{
+    hash::Hash,
+    os::fd::{AsFd as _, AsRawFd},
+    path::Path,
+};
 
 use crate::{
     generated::bpf_prog_type::BPF_PROG_TYPE_CGROUP_SOCK,
@@ -67,7 +71,9 @@ impl CgroupSock {
     ///
     /// The returned value can be used to detach, see [CgroupSock::detach].
     pub fn attach<T: AsRawFd>(&mut self, cgroup: T) -> Result<CgroupSockLinkId, ProgramError> {
-        let prog_fd = self.data.fd_or_err()?;
+        let prog_fd = self.fd()?;
+        let prog_fd = prog_fd.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
         let cgroup_fd = cgroup.as_raw_fd();
         let attach_type = self.data.expected_attach_type.unwrap();
         if KernelVersion::current().unwrap() >= KernelVersion::new(5, 7, 0) {

aya/src/programs/cgroup_sock_addr.rs

@@ -3,7 +3,11 @@
 pub use aya_obj::programs::CgroupSockAddrAttachType;
 
 use crate::util::KernelVersion;
-use std::{hash::Hash, os::fd::AsRawFd, path::Path};
+use std::{
+    hash::Hash,
+    os::fd::{AsFd as _, AsRawFd},
+    path::Path,
+};
 
 use crate::{
     generated::bpf_prog_type::BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
@@ -68,7 +72,9 @@ impl CgroupSockAddr {
     ///
     /// The returned value can be used to detach, see [CgroupSockAddr::detach].
     pub fn attach<T: AsRawFd>(&mut self, cgroup: T) -> Result<CgroupSockAddrLinkId, ProgramError> {
-        let prog_fd = self.data.fd_or_err()?;
+        let prog_fd = self.fd()?;
+        let prog_fd = prog_fd.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
         let cgroup_fd = cgroup.as_raw_fd();
         let attach_type = self.data.expected_attach_type.unwrap();
         if KernelVersion::current().unwrap() >= KernelVersion::new(5, 7, 0) {

aya/src/programs/cgroup_sockopt.rs

@@ -3,7 +3,11 @@
 pub use aya_obj::programs::CgroupSockoptAttachType;
 
 use crate::util::KernelVersion;
-use std::{hash::Hash, os::fd::AsRawFd, path::Path};
+use std::{
+    hash::Hash,
+    os::fd::{AsFd as _, AsRawFd},
+    path::Path,
+};
 
 use crate::{
     generated::bpf_prog_type::BPF_PROG_TYPE_CGROUP_SOCKOPT,
@@ -65,7 +69,9 @@ impl CgroupSockopt {
     ///
     /// The returned value can be used to detach, see [CgroupSockopt::detach].
     pub fn attach<T: AsRawFd>(&mut self, cgroup: T) -> Result<CgroupSockoptLinkId, ProgramError> {
-        let prog_fd = self.data.fd_or_err()?;
+        let prog_fd = self.fd()?;
+        let prog_fd = prog_fd.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
         let cgroup_fd = cgroup.as_raw_fd();
         let attach_type = self.data.expected_attach_type.unwrap();
         if KernelVersion::current().unwrap() >= KernelVersion::new(5, 7, 0) {

aya/src/programs/cgroup_sysctl.rs

@@ -1,7 +1,10 @@
 //! Cgroup sysctl programs.
 
 use crate::util::KernelVersion;
-use std::{hash::Hash, os::fd::AsRawFd};
+use std::{
+    hash::Hash,
+    os::fd::{AsFd as _, AsRawFd},
+};
 
 use crate::{
     generated::{bpf_attach_type::BPF_CGROUP_SYSCTL, bpf_prog_type::BPF_PROG_TYPE_CGROUP_SYSCTL},
@@ -60,7 +63,9 @@ impl CgroupSysctl {
     ///
     /// The returned value can be used to detach, see [CgroupSysctl::detach].
     pub fn attach<T: AsRawFd>(&mut self, cgroup: T) -> Result<CgroupSysctlLinkId, ProgramError> {
-        let prog_fd = self.data.fd_or_err()?;
+        let prog_fd = self.fd()?;
+        let prog_fd = prog_fd.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
         let cgroup_fd = cgroup.as_raw_fd();
 
         if KernelVersion::current().unwrap() >= KernelVersion::new(5, 7, 0) {

aya/src/programs/extension.rs

@@ -1,5 +1,5 @@
 //! Extension programs.
-use std::os::fd::{AsFd as _, AsRawFd as _, OwnedFd};
+use std::os::fd::{AsFd as _, AsRawFd as _, BorrowedFd, OwnedFd};
 use thiserror::Error;
 
 use object::Endianness;
@@ -42,8 +42,9 @@ pub enum ExtensionError {
 /// prog.attach("eth0", XdpFlags::default())?;
 ///
 /// let prog_fd = prog.fd().unwrap();
+/// let prog_fd = prog_fd.try_clone().unwrap();
 /// let ext: &mut Extension = bpf.program_mut("extension").unwrap().try_into()?;
-/// ext.load(prog_fd, "function_to_replace")?;
+/// ext.load(&prog_fd, "function_to_replace")?;
 /// ext.attach()?;
 /// Ok::<(), aya::BpfError>(())
 /// ```
@@ -68,12 +69,12 @@ impl Extension {
     /// The extension code will be loaded but inactive until it's attached.
     /// 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();
+    pub fn load(&mut self, program: &ProgramFd, func_name: &str) -> Result<(), ProgramError> {
+        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);
-        self.data.attach_prog_fd = Some(target_prog_fd);
+        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)
     }
@@ -86,7 +87,9 @@ impl Extension {
     /// The returned value can be used to detach the extension and restore the
     /// original function, see [Extension::detach].
     pub fn attach(&mut self) -> Result<ExtensionLinkId, ProgramError> {
-        let prog_fd = self.data.fd_or_err()?;
+        let prog_fd = self.fd()?;
+        let prog_fd = prog_fd.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
         let target_fd = self.data.attach_prog_fd.ok_or(ProgramError::NotLoaded)?;
         let btf_id = self.data.attach_btf_id.ok_or(ProgramError::NotLoaded)?;
         // the attach type must be set as 0, which is bpf_attach_type::BPF_CGROUP_INET_INGRESS
@@ -113,18 +116,26 @@ impl Extension {
     /// original function, see [Extension::detach].
     pub fn attach_to_program(
         &mut self,
-        program: ProgramFd,
+        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()?;
+        let prog_fd = self.fd()?;
+        let prog_fd = prog_fd.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
         // 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)
-            .map_err(|(_, io_error)| SyscallError {
-                call: "bpf_link_create",
-                io_error,
-            })?;
+        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)| SyscallError {
+            call: "bpf_link_create",
+            io_error,
+        })?;
         self.data
             .links
             .insert(ExtensionLink::new(FdLink::new(link_fd)))
@@ -149,7 +160,7 @@ 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<(OwnedFd, u32), ProgramError> {
+fn get_btf_info(prog_fd: BorrowedFd<'_>, func_name: &str) -> Result<(OwnedFd, u32), ProgramError> {
     // retrieve program information
     let info = sys::bpf_prog_get_info_by_fd(prog_fd, &mut [])?;
 

aya/src/programs/lirc_mode2.rs

@@ -1,5 +1,5 @@
 //! Lirc programs.
-use std::os::fd::{AsRawFd, IntoRawFd as _, RawFd};
+use std::os::fd::{AsFd as _, AsRawFd, BorrowedFd, IntoRawFd as _, RawFd};
 
 use crate::{
     generated::{bpf_attach_type::BPF_LIRC_MODE2, bpf_prog_type::BPF_PROG_TYPE_LIRC_MODE2},
@@ -61,7 +61,9 @@ impl LircMode2 {
     ///
     /// The returned value can be used to detach, see [LircMode2::detach].
     pub fn attach<T: AsRawFd>(&mut self, lircdev: T) -> Result<LircLinkId, ProgramError> {
-        let prog_fd = self.data.fd_or_err()?;
+        let prog_fd = self.fd()?;
+        let prog_fd = prog_fd.as_fd();
+        let prog_fd = prog_fd.as_raw_fd();
         let lircdev_fd = lircdev.as_raw_fd();
 
         bpf_prog_attach(prog_fd, lircdev_fd, BPF_LIRC_MODE2).map_err(|(_, io_error)| {
@@ -128,7 +130,9 @@ impl LircLink {
 
     /// Get ProgramInfo from this link
     pub fn info(&self) -> Result<ProgramInfo, ProgramError> {
-        ProgramInfo::new_from_fd(self.prog_fd)
+        // SAFETY: TODO(https://github.com/aya-rs/aya/issues/612): make this safe by not holding `RawFd`s.
+        let prog_fd = unsafe { BorrowedFd::borrow_raw(self.prog_fd) };
+        ProgramInfo::new_from_fd(prog_fd)
     }
 }