Omar ElsayedandZen Dodd a68b32cd5c Fix ENOENT when resolving kernel pseudo-paths in ona_open (#1054) ...

* Fix ona_open to safely resolve bash process substitution pseudo-paths
Bash process substitution (e.g., `<(...)` or `>(...)`) exposes file
descriptors as symlinks under `/proc/self/fd/X` pointing to kernel
pseudo-paths such as `pipe:[12345]`. Previously, `ona_open()` would read
this target and attempt to resolve it as a literal file path on disk,
causing the operation to fail with `ENOENT` and breaking legitimate local
process substitution.

This patch safely intercepts and resolves these pseudo-paths while
maintaining strict confinement boundaries and averting TOCTOU risks:

- Detects kernel pseudo-paths (`pipe:[`, `socket:[`, `anon_inode:`)
  only when `fd_pin_tail` confirms the path resolves precisely to a
  direct child of a valid FD directory.
- Categorically rejects pseudo-path resolution if `confine_root` is
  active (yielding `ENOENT`).
- Strips `O_NOFOLLOW` for legitimate leaf pseudo-paths, allowing
  `openat()` to correctly delegate resolution.
- Reverts `fd_pin_tail` to its upstream signature, as manual PID
  validation is no longer required due to the secure `openat()` design.

* testsuite: expect pseudo-path skip on Alma
* syscall: reject trailing pseudo-path components

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Co-authored-by: Zen Dodd <mail@steadytao.com>

2026-09-03 08:11:16 +10:00

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Fix ENOENT when resolving kernel pseudo-paths in ona_open (#1054)

2026-09-03 08:11:16 +10:00

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