# When yama is enabled in the kernel it might be used to filter any user # space access which requires PTRACE_MODE_ATTACH like ptrace attach, access # to /proc/PID/{mem,personality,stack,syscall}, and the syscalls # process_vm_readv and process_vm_writev which are used for interprocess # services, communication and introspection (like synchronisation, signaling, # debugging, tracing and profiling) of processes. # # Usage of ptrace attach is restricted by normal user permissions. Normal # unprivileged processes cannot interact through ptrace with processes # that they cannot send signals to or processes that are running set-uid # or set-gid. # # yama ptrace scope can be used to reduce these permissions even more. # This should normally not be done because it will break various programs # relying on the default ptrace security restrictions. But can be used # if you don't have any other way to separate processes in their own # domains. A different way to restrict ptrace is to set the selinux # deny_ptrace boolean. Both mechanisms will break some programs relying # on the ptrace system call and might force users to elevate their # priviliges to root to do their work. # # For more information see Documentation/security/Yama.txt in the kernel # sources. Which also describes the defaults when CONFIG_SECURITY_YAMA # is enabled in a kernel build (currently 1 for ptrace_scope). # # This runtime kernel parameter can be set to the following options: # (Note that setting this to anything except zero will break programs!) # # 0 - Default attach security permissions. # 1 - Restricted attach. Only child processes plus normal permissions. # 2 - Admin-only attach. Only executables with CAP_SYS_PTRACE. # 3 - No attach. No process may call ptrace at all. Irrevocable. # kernel.yama.ptrace_scope = 0