Make various Program::attach_* methods work on shared receiver

Attaching a BPF program currently provides exclusive access to the
Program object, but it's not exactly clear why that is. Given that
libbpf work on const pointers, let's switch over to having those methods
work on a shared receiver instead, eliminating a bunch of possible
borrow conflicts.

Refs: #953

Signed-off-by: Daniel Müller <deso@posteo.net>

examples/tcp_option/src/main.rs

@@ -106,7 +106,7 @@ fn main() -> Result<()> {
     open.maps.rodata_data.targ_ip = u32::from_be_bytes(ip.octets()).to_be();
     open.maps.rodata_data.data_such_as_trace_id = opts.trace_id;
 
-    let mut skel = open.load()?;
+    let skel = open.load()?;
 
     let cgroup_fd = OpenOptions::new()
         .read(true)

libbpf-rs/CHANGELOG.md

@@ -4,6 +4,8 @@ Unreleased
   - Deprecated `Program::get_id_by_fd`
 - Renamed `Program::get_fd_by_id` to `fd_from_id`
   - Deprecated `Program::get_fd_by_id`
+- Adjusted various `Program::attach_*` methods to work on shared
+  receivers
 - Adjusted `PerfBufferBuilder` to work with `MapCore` objects
 
 

libbpf-rs/src/program.rs

@@ -743,7 +743,7 @@ impl<'obj> ProgramMut<'obj> {
     }
 
     /// Auto-attach based on prog section
-    pub fn attach(&mut self) -> Result<Link> {
+    pub fn attach(&self) -> Result<Link> {
         let ptr = unsafe { libbpf_sys::bpf_program__attach(self.ptr.as_ptr()) };
         let ptr = validate_bpf_ret(ptr).context("failed to attach BPF program")?;
         // SAFETY: the pointer came from libbpf and has been checked for errors.
@@ -753,7 +753,7 @@ impl<'obj> ProgramMut<'obj> {
 
     /// Attach this program to a
     /// [cgroup](https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html).
-    pub fn attach_cgroup(&mut self, cgroup_fd: i32) -> Result<Link> {
+    pub fn attach_cgroup(&self, cgroup_fd: i32) -> Result<Link> {
         let ptr = unsafe { libbpf_sys::bpf_program__attach_cgroup(self.ptr.as_ptr(), cgroup_fd) };
         let ptr = validate_bpf_ret(ptr).context("failed to attach cgroup")?;
         // SAFETY: the pointer came from libbpf and has been checked for errors.
@@ -762,7 +762,7 @@ impl<'obj> ProgramMut<'obj> {
     }
 
     /// Attach this program to a [perf event](https://linux.die.net/man/2/perf_event_open).
-    pub fn attach_perf_event(&mut self, pfd: i32) -> Result<Link> {
+    pub fn attach_perf_event(&self, pfd: i32) -> Result<Link> {
         let ptr = unsafe { libbpf_sys::bpf_program__attach_perf_event(self.ptr.as_ptr(), pfd) };
         let ptr = validate_bpf_ret(ptr).context("failed to attach perf event")?;
         // SAFETY: the pointer came from libbpf and has been checked for errors.
@@ -773,7 +773,7 @@ impl<'obj> ProgramMut<'obj> {
     /// Attach this program to a [userspace
     /// probe](https://www.kernel.org/doc/html/latest/trace/uprobetracer.html).
     pub fn attach_uprobe<T: AsRef<Path>>(
-        &mut self,
+        &self,
         retprobe: bool,
         pid: i32,
         binary_path: T,
@@ -800,7 +800,7 @@ impl<'obj> ProgramMut<'obj> {
     /// probe](https://www.kernel.org/doc/html/latest/trace/uprobetracer.html),
     /// providing additional options.
     pub fn attach_uprobe_with_opts(
-        &mut self,
+        &self,
         pid: i32,
         binary_path: impl AsRef<Path>,
         func_offset: usize,
@@ -843,7 +843,7 @@ impl<'obj> ProgramMut<'obj> {
 
     /// Attach this program to a [kernel
     /// probe](https://www.kernel.org/doc/html/latest/trace/kprobetrace.html).
-    pub fn attach_kprobe<T: AsRef<str>>(&mut self, retprobe: bool, func_name: T) -> Result<Link> {
+    pub fn attach_kprobe<T: AsRef<str>>(&self, retprobe: bool, func_name: T) -> Result<Link> {
         let func_name = util::str_to_cstring(func_name.as_ref())?;
         let func_name_ptr = func_name.as_ptr();
         let ptr = unsafe {
@@ -856,11 +856,7 @@ impl<'obj> ProgramMut<'obj> {
     }
 
     /// Attach this program to the specified syscall
-    pub fn attach_ksyscall<T: AsRef<str>>(
-        &mut self,
-        retprobe: bool,
-        syscall_name: T,
-    ) -> Result<Link> {
+    pub fn attach_ksyscall<T: AsRef<str>>(&self, retprobe: bool, syscall_name: T) -> Result<Link> {
         let opts = libbpf_sys::bpf_ksyscall_opts {
             sz: size_of::<libbpf_sys::bpf_ksyscall_opts>() as _,
             retprobe,
@@ -879,7 +875,7 @@ impl<'obj> ProgramMut<'obj> {
     }
 
     fn attach_tracepoint_impl(
-        &mut self,
+        &self,
         tp_category: &str,
         tp_name: &str,
         tp_opts: Option<TracepointOpts>,
@@ -918,7 +914,7 @@ impl<'obj> ProgramMut<'obj> {
     /// Attach this program to a [kernel
     /// tracepoint](https://www.kernel.org/doc/html/latest/trace/tracepoints.html).
     pub fn attach_tracepoint(
-        &mut self,
+        &self,
         tp_category: impl AsRef<str>,
         tp_name: impl AsRef<str>,
     ) -> Result<Link> {
@@ -929,7 +925,7 @@ impl<'obj> ProgramMut<'obj> {
     /// tracepoint](https://www.kernel.org/doc/html/latest/trace/tracepoints.html),
     /// providing additional options.
     pub fn attach_tracepoint_with_opts(
-        &mut self,
+        &self,
         tp_category: impl AsRef<str>,
         tp_name: impl AsRef<str>,
         tp_opts: TracepointOpts,
@@ -939,7 +935,7 @@ impl<'obj> ProgramMut<'obj> {
 
     /// Attach this program to a [raw kernel
     /// tracepoint](https://lwn.net/Articles/748352/).
-    pub fn attach_raw_tracepoint<T: AsRef<str>>(&mut self, tp_name: T) -> Result<Link> {
+    pub fn attach_raw_tracepoint<T: AsRef<str>>(&self, tp_name: T) -> Result<Link> {
         let tp_name = util::str_to_cstring(tp_name.as_ref())?;
         let tp_name_ptr = tp_name.as_ptr();
         let ptr = unsafe {
@@ -952,7 +948,7 @@ impl<'obj> ProgramMut<'obj> {
     }
 
     /// Attach to an [LSM](https://en.wikipedia.org/wiki/Linux_Security_Modules) hook
-    pub fn attach_lsm(&mut self) -> Result<Link> {
+    pub fn attach_lsm(&self) -> Result<Link> {
         let ptr = unsafe { libbpf_sys::bpf_program__attach_lsm(self.ptr.as_ptr()) };
         let ptr = validate_bpf_ret(ptr).context("failed to attach LSM")?;
         // SAFETY: the pointer came from libbpf and has been checked for errors.
@@ -961,7 +957,7 @@ impl<'obj> ProgramMut<'obj> {
     }
 
     /// Attach to a [fentry/fexit kernel probe](https://lwn.net/Articles/801479/)
-    pub fn attach_trace(&mut self) -> Result<Link> {
+    pub fn attach_trace(&self) -> Result<Link> {
         let ptr = unsafe { libbpf_sys::bpf_program__attach_trace(self.ptr.as_ptr()) };
         let ptr = validate_bpf_ret(ptr).context("failed to attach fentry/fexit kernel probe")?;
         // SAFETY: the pointer came from libbpf and has been checked for errors.
@@ -983,7 +979,7 @@ impl<'obj> ProgramMut<'obj> {
     }
 
     /// Attach this program to [XDP](https://lwn.net/Articles/825998/)
-    pub fn attach_xdp(&mut self, ifindex: i32) -> Result<Link> {
+    pub fn attach_xdp(&self, ifindex: i32) -> Result<Link> {
         let ptr = unsafe { libbpf_sys::bpf_program__attach_xdp(self.ptr.as_ptr(), ifindex) };
         let ptr = validate_bpf_ret(ptr).context("failed to attach XDP program")?;
         // SAFETY: the pointer came from libbpf and has been checked for errors.
@@ -992,7 +988,7 @@ impl<'obj> ProgramMut<'obj> {
     }
 
     /// Attach this program to [netns-based programs](https://lwn.net/Articles/819618/)
-    pub fn attach_netns(&mut self, netns_fd: i32) -> Result<Link> {
+    pub fn attach_netns(&self, netns_fd: i32) -> Result<Link> {
         let ptr = unsafe { libbpf_sys::bpf_program__attach_netns(self.ptr.as_ptr(), netns_fd) };
         let ptr = validate_bpf_ret(ptr).context("failed to attach network namespace program")?;
         // SAFETY: the pointer came from libbpf and has been checked for errors.
@@ -1001,7 +997,7 @@ impl<'obj> ProgramMut<'obj> {
     }
 
     fn attach_usdt_impl(
-        &mut self,
+        &self,
         pid: i32,
         binary_path: &Path,
         usdt_provider: &str,
@@ -1040,7 +1036,7 @@ impl<'obj> ProgramMut<'obj> {
     /// point. The entry point of the program must be defined with
     /// `SEC("usdt")`.
     pub fn attach_usdt(
-        &mut self,
+        &self,
         pid: i32,
         binary_path: impl AsRef<Path>,
         usdt_provider: impl AsRef<str>,
@@ -1059,7 +1055,7 @@ impl<'obj> ProgramMut<'obj> {
     /// point, providing additional options. The entry point of the program must
     /// be defined with `SEC("usdt")`.
     pub fn attach_usdt_with_opts(
-        &mut self,
+        &self,
         pid: i32,
         binary_path: impl AsRef<Path>,
         usdt_provider: impl AsRef<str>,
@@ -1078,7 +1074,7 @@ impl<'obj> ProgramMut<'obj> {
     /// Attach this program to a
     /// [BPF Iterator](https://www.kernel.org/doc/html/latest/bpf/bpf_iterators.html).
     /// The entry point of the program must be defined with `SEC("iter")` or `SEC("iter.s")`.
-    pub fn attach_iter(&mut self, map_fd: BorrowedFd<'_>) -> Result<Link> {
+    pub fn attach_iter(&self, map_fd: BorrowedFd<'_>) -> Result<Link> {
         let mut linkinfo = libbpf_sys::bpf_iter_link_info::default();
         linkinfo.map.map_fd = map_fd.as_raw_fd() as _;
         let attach_opt = libbpf_sys::bpf_iter_attach_opts {

libbpf-rs/tests/test.rs

@@ -861,7 +861,7 @@ fn test_object_link_pin() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("runqslower.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__sched_wakeup");
+    let prog = get_prog_mut(&mut obj, "handle__sched_wakeup");
     let mut link = prog.attach().expect("failed to attach prog");
 
     let path = "/sys/fs/bpf/mylink";
@@ -941,7 +941,7 @@ fn test_object_ringbuf_raw() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("ringbuf.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
+    let prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
     let _link = prog.attach().expect("failed to attach prog");
 
     static mut V1: i32 = 0;
@@ -1022,7 +1022,7 @@ fn test_object_ringbuf_err_callback() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("ringbuf.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
+    let prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
     let _link = prog.attach().expect("failed to attach prog");
 
     // Immediately trigger an error that should be reported back to the consume_raw() or poll_raw()
@@ -1084,7 +1084,7 @@ fn test_object_ringbuf() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("ringbuf.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
+    let prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
     let _link = prog.attach().expect("failed to attach prog");
 
     static mut V1: i32 = 0;
@@ -1169,7 +1169,7 @@ fn test_object_ringbuf_closure() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("ringbuf.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
+    let prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
     let _link = prog.attach().expect("failed to attach prog");
 
     let (sender1, receiver1) = channel();
@@ -1243,7 +1243,7 @@ fn test_object_ringbuf_with_closed_map() {
 
         {
             let mut obj = get_test_object("tracepoint.bpf.o");
-            let mut prog = get_prog_mut(&mut obj, "handle__tracepoint");
+            let prog = get_prog_mut(&mut obj, "handle__tracepoint");
             let _link = prog
                 .attach_tracepoint("syscalls", "sys_enter_getpid")
                 .expect("failed to attach prog");
@@ -1293,7 +1293,7 @@ fn test_object_user_ringbuf() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("user_ringbuf.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
+    let prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
     let _link = prog.attach().expect("failed to attach prog");
     let urb_map = get_map_mut(&mut obj, "user_ringbuf");
     let user_ringbuf = UserRingBuffer::new(&urb_map).expect("failed to create user ringbuf");
@@ -1334,7 +1334,7 @@ fn test_object_user_ringbuf_reservation_too_big() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("user_ringbuf.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
+    let prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
     let _link = prog.attach().expect("failed to attach prog");
     let urb_map = get_map_mut(&mut obj, "user_ringbuf");
     let user_ringbuf = UserRingBuffer::new(&urb_map).expect("failed to create user ringbuf");
@@ -1351,7 +1351,7 @@ fn test_object_user_ringbuf_not_enough_space() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("user_ringbuf.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
+    let prog = get_prog_mut(&mut obj, "handle__sys_enter_getpid");
     let _link = prog.attach().expect("failed to attach prog");
     let urb_map = get_map_mut(&mut obj, "user_ringbuf");
     let user_ringbuf = UserRingBuffer::new(&urb_map).expect("failed to create user ringbuf");
@@ -1372,7 +1372,7 @@ fn test_object_task_iter() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("taskiter.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "dump_pid");
+    let prog = get_prog_mut(&mut obj, "dump_pid");
     let link = prog.attach().expect("failed to attach prog");
     let mut iter = Iter::new(&link).expect("failed to create iterator");
 
@@ -1433,7 +1433,7 @@ fn test_object_map_iter() {
     }
 
     let mut obj = get_test_object("mapiter.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "map_iter");
+    let prog = get_prog_mut(&mut obj, "map_iter");
     let link = prog
         .attach_iter(map.as_fd())
         .expect("failed to attach map iter prog");
@@ -1571,7 +1571,7 @@ fn test_object_usdt() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("usdt.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__usdt");
+    let prog = get_prog_mut(&mut obj, "handle__usdt");
 
     let path = current_exe().expect("failed to find executable name");
     let _link = prog
@@ -1600,7 +1600,7 @@ fn test_object_usdt_cookie() {
 
     let cookie_val = 1337u16;
     let mut obj = get_test_object("usdt.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__usdt_with_cookie");
+    let prog = get_prog_mut(&mut obj, "handle__usdt_with_cookie");
 
     let path = current_exe().expect("failed to find executable name");
     let _link = prog
@@ -1703,7 +1703,7 @@ fn test_object_tracepoint() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("tracepoint.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__tracepoint");
+    let prog = get_prog_mut(&mut obj, "handle__tracepoint");
     let _link = prog
         .attach_tracepoint("syscalls", "sys_enter_getpid")
         .expect("failed to attach prog");
@@ -1726,7 +1726,7 @@ fn test_object_tracepoint_with_opts() {
 
     let cookie_val = 42u16;
     let mut obj = get_test_object("tracepoint.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__tracepoint_with_cookie");
+    let prog = get_prog_mut(&mut obj, "handle__tracepoint_with_cookie");
 
     let opts = TracepointOpts {
         cookie: cookie_val.into(),
@@ -1759,7 +1759,7 @@ fn test_object_uprobe_with_opts() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("uprobe.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__uprobe");
+    let prog = get_prog_mut(&mut obj, "handle__uprobe");
 
     let pid = unsafe { libc::getpid() };
     let path = current_exe().expect("failed to find executable name");
@@ -1790,7 +1790,7 @@ fn test_object_uprobe_with_cookie() {
 
     let cookie_val = 5u16;
     let mut obj = get_test_object("uprobe.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__uprobe_with_cookie");
+    let prog = get_prog_mut(&mut obj, "handle__uprobe_with_cookie");
 
     let pid = unsafe { libc::getpid() };
     let path = current_exe().expect("failed to find executable name");
@@ -1869,7 +1869,7 @@ fn test_object_perf_buffer_raw() {
 
     let cookie_val = 42u16;
     let mut obj = get_test_object("tracepoint.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__tracepoint_with_cookie_pb");
+    let prog = get_prog_mut(&mut obj, "handle__tracepoint_with_cookie_pb");
 
     let opts = TracepointOpts {
         cookie: cookie_val.into(),
@@ -2002,7 +2002,7 @@ fn test_attach_ksyscall() {
     bump_rlimit_mlock();
 
     let mut obj = get_test_object("ksyscall.bpf.o");
-    let mut prog = get_prog_mut(&mut obj, "handle__ksyscall");
+    let prog = get_prog_mut(&mut obj, "handle__ksyscall");
     let _link = prog
         .attach_ksyscall(false, "kill")
         .expect("failed to attach prog");