Fix Unprivileged user-namespaces can bypass exePath validation on Linux machine

[Zhidong Peng (ZhidongPeng)]

• extend linux eBPF program and maps to capture executable identity (device and inode numbers).
• when match identity exePath for linux platform, it compares its file metadata.dev() and metadata.ino() instead of the exePath string match.
• Impl pentest C3 and ensure the test result passed

=== WS-S9-exepath-identity: enforce + deny; identity restricts to exePath=/usr/bin/curl
  ... waiting 20s for rule refresh ...
[PASS] WS-S9-exepath-identity/python_caller_denied  expected=403 actual=403 path=/machine/?comp=goalstate
[PASS] WS-S9-exepath-identity/curl_caller_allowed  expected=200 actual=200 (curl invocation)
[PASS] C3  expected=403 actual=403; caller /proc/<pid>/exe bind-mounted over allow-listed /usr/bin/curl