- Child installs a seccomp filter with a listener; a supervisor thread
resolves the path of write-type syscalls (cwd, dirfd, .., symlinks,
/proc/self, /dev/stdout, both ends of rename/link) and answers
CONTINUE or EACCES; IPv4/IPv6 sockets are refused
- Probe order Landlock -> seccomp -> none, checked in a throwaway child;
CST_SANDBOX=landlock|seccomp|off
- curl connect failures count as sandbox refusals
- test_sandbox runs the detected sandbox and forced seccomp, with escape,
symlink, rename, link, chmod, stdout, ENOENT, background and network cases
- Docs: platform matrix, limits (not a security boundary, Yama and
background jobs)