Merge ecb68d1ebb into 9379a18c8a

src/agent/rustjail/src/cgroups/fs/mod.rs

@@ -1167,21 +1167,37 @@ impl Manager {
         })
     }
 
-    pub fn subcgroup(&self) -> &str {
-        // Check if we're in a Docker-in-Docker setup by verifying:
-        // 1. We're using cgroups v2 (which restricts direct process control)
-        // 2. An "init" subdirectory exists (used by DinD for process delegation)
-        let is_dind = cgroups::hierarchies::is_cgroup2_unified_mode()
-            && cgroups::hierarchies::auto()
-                .root()
-                .join(&self.cpath)
-                .join("init")
-                .exists();
-        if is_dind {
-            "/init/"
-        } else {
-            "/"
+    pub fn subcgroup(&self, init_pid: pid_t, container_cgroup: &str) -> Result<String> {
+        if init_pid <= 0 || !cgroups::hierarchies::is_cgroup2_unified_mode() {
+            return Ok("/".into());
         }
+        // get sub-cgroup from container init pid
+        let cgroup_info = fs::read_to_string(format!("/proc/{}/cgroup", init_pid))?;
+        for line in cgroup_info.lines() {
+            // the entry for cgroup v2 is always in the format "0::$PATH"
+            // see https://docs.kernel.org/admin-guide/cgroup-v2.html
+            if let Some((_, init_cgroup_path)) = line.split_once("0::") {
+                let container_cgroup_path = format!("/{}", container_cgroup);
+                debug!(
+                    sl(),
+                    "subcgroup info: init_pid {}, init_cgroup_path {}, container_cgroup_path {}",
+                    init_pid,
+                    init_cgroup_path,
+                    container_cgroup_path
+                );
+                // get relative cgroup path of init_cgroup_path to container_cgroup_path
+                // container_cgroup_path: /a/b/c.slice
+                // init_cgroup_path: /a/b/c.slice/d.scope or /a/b/c.slice
+                if let Some((_, sub_path)) = init_cgroup_path.split_once(&container_cgroup_path) {
+                    match sub_path {
+                        "" => return Ok("/".into()),
+                        _ => return Ok(sub_path.into()),
+                    }
+                };
+                break;
+            }
+        }
+        Ok("/".into())
     }
 
     fn get_paths_and_mounts(

src/agent/rustjail/src/cgroups/mod.rs

@@ -30,6 +30,10 @@ pub trait Manager {
         Err(anyhow!("not supported!".to_string()))
     }
 
+    fn set_init_pid(&mut self, _pid: i32) -> Result<()> {
+        Err(anyhow!("not supported!"))
+    }
+
     fn get_pids(&self) -> Result<Vec<i32>> {
         Err(anyhow!("not supported!"))
     }

src/agent/rustjail/src/cgroups/systemd/manager.rs

@@ -37,13 +37,15 @@ pub struct Manager {
     fs_manager: FsManager,
     // cgroup version for different dbus properties
     cg_hierarchy: CgroupHierarchy,
+    // pid of first process in container
+    init_pid: pid_t,
 }
 
 impl CgroupManager for Manager {
     fn apply(&self, pid: pid_t) -> Result<()> {
         if self.dbus_client.unit_exists()? {
-            let subcgroup = self.fs_manager.subcgroup();
-            self.dbus_client.add_process(pid, subcgroup)?;
+            let subcgroup = self.fs_manager.subcgroup(self.init_pid, &self.cpath)?;
+            self.dbus_client.add_process(pid, subcgroup.as_str())?;
         } else {
             self.dbus_client.start_unit(
                 (pid as u32).try_into().unwrap(),
@@ -55,6 +57,13 @@ impl CgroupManager for Manager {
         Ok(())
     }
 
+    fn set_init_pid(&mut self, pid: pid_t) -> Result<()> {
+        if self.init_pid == 0 {
+            self.init_pid = pid;
+        }
+        Ok(())
+    }
+
     fn set(&self, r: &LinuxResources, _: bool) -> Result<()> {
         let mut properties: Properties = vec![];
 
@@ -130,6 +139,7 @@ impl Manager {
             } else {
                 CgroupHierarchy::Legacy
             },
+            init_pid: 0,
         })
     }
 }

src/agent/rustjail/src/container.rs

@@ -1216,7 +1216,7 @@ impl BaseContainer for LinuxContainer {
             &logger,
             spec,
             &p,
-            self.cgroup_manager.as_ref(),
+            self.cgroup_manager.as_mut(),
             self.config.use_systemd_cgroup,
             &st,
             &mut pipe_w,
@@ -1517,7 +1517,7 @@ async fn join_namespaces(
     logger: &Logger,
     spec: &Spec,
     p: &Process,
-    cm: &(dyn Manager + Send + Sync),
+    cm: &mut (dyn Manager + Send + Sync),
     use_systemd_cgroup: bool,
     st: &OCIState,
     pipe_w: &mut PipeStream,
@@ -1583,6 +1583,8 @@ async fn join_namespaces(
     }
 
     if p.init && res.is_some() {
+        info!(logger, "set init pid {} for {:p}", p.pid, cm);
+        cm.set_init_pid(p.pid)?;
         info!(logger, "set properties to cgroups!");
         cm.set(res.unwrap(), false)?;
     }