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Mark Johnston
8e6bc7b3e9
When an fdescfs mount has the nodup option set, fdesc_lookup(/dev/fd/n) returns the vnode referenced by file descriptor n, rather than returning an fdescfs vnode. This meant that fd metadata attached to fd n was not preserved when reopening the file, which is contrary to the expected semantics for capsicum rights and the UF_RESOLVE_BENEATH fd flag. For regular fdescfs mounts, this metadata is copied via dupfdopen(). Fix the problem by passing up this metadata through the nameidata structure. Thus, if one opens /dev/fd/n, the returned fd will inherit UF_RESOLVE_BENEATH and the capability rights of fd n. Add some regression tests as well. Approved by: so Security: FreeBSD-SA-26:66.jail Security: CVE-2026-101304 Reported by: Jan Bramkamp Reviewed by: kib Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D59886