feat: add auto bpf mount

examples/daemonset/agent.yaml

@@ -142,6 +142,7 @@ spec:
           volumeMounts:
             - name: bpf
               mountPath: /sys/fs/bpf
+              mountPropagation: Bidirectional
             - name: cgroup
               mountPath: /sys/fs/cgroup
               readOnly: true

internal/ebpf/mount_linux.go

@@ -0,0 +1,38 @@
+package ebpf
+
+import (
+	"fmt"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+// mountBPFFS ensures that /sys/fs/bpf is mounted as a BPF filesystem.
+func mountBPFFS() error {
+	const bpfPath = "/sys/fs/bpf"
+
+	// Check if directory exists, create if not
+	if err := os.MkdirAll(bpfPath, 0o750); err != nil {
+		return fmt.Errorf("create bpf mount point: %w", err)
+	}
+
+	// Check if already mounted
+	var stat unix.Statfs_t
+	if err := unix.Statfs(bpfPath, &stat); err != nil {
+		return fmt.Errorf("statfs %s: %w", bpfPath, err)
+	}
+
+	// Magic number for BPF_FS is 0xCAFE4A11
+	const bpfFsMagic = 0xCAFE4A11
+	if stat.Type == bpfFsMagic {
+		return nil // Already mounted
+	}
+
+	// Mount it
+	// mount(source, target, fstype, flags, data)
+	if err := unix.Mount("bpf", bpfPath, "bpf", 0, "mode=0700"); err != nil {
+		return fmt.Errorf("mount bpffs: %w", err)
+	}
+
+	return nil
+}

internal/ebpf/preflight.go

@@ -30,6 +30,13 @@ func (r PreflightReport) HasErrors() bool {
 func Preflight(cfg config.Config) PreflightReport {
 	report := PreflightReport{}
 
+	if err := mountBPFFS(); err != nil {
+		report.Issues = append(report.Issues, PreflightIssue{
+			Component: "bpffs",
+			Message:   fmt.Sprintf("failed to mount bpffs: %v", err),
+		})
+	}
+
 	if err := rlimit.RemoveMemlock(); err != nil {
 		report.Issues = append(report.Issues, PreflightIssue{
 			Component: "memlock",