Files
av-club/sidecar
pastilhas a467000b3d a symlink the owner put inside the root may lead out of it
Two failures on 2026-09-09, one cause each, both found by a 212-track album that would not convert.

── Symlinks ──

paths.ts ran realpath FIRST and required the resolved path to be inside WORK_ROOT, so a link in the
owner's home pointing at another disk was refused. On a machine whose home is BUILT from such links —
~/Music, ~/Movies, ~/Torrents each pointing at a mount — that leaves av-club able to see almost
nothing. It refused every track of a folder the owner had open in the file browser at the time.

That is the tell. The file browser decides what the owner may touch and it launches these jobs; its
resolveUserPath checks the path as written and never calls realpath. Two confinement rules over the
same files means the platform offers a right-click action its own sidecar cannot perform.

What the strict rule was worth is smaller than it looks: this process runs AS the owner, so it reads
nothing the owner cannot already read, and a link out of home reaches only more of the owner's disks.
realpath-first was never the privilege boundary — the OS is.

`..` is now refused rather than normalised, which is what realpath-first actually bought. Normalising
is not what the kernel does: for /home/me/Music/.. the string says /home/me while the kernel follows
Music to another filesystem first. Refusing removes the divergence instead of picking a side.

The narrower claim that remains, and is the one to defend: a caller cannot NAME a path outside the
root; they can only follow a link the owner put inside it.

── The token ──

requireToken() threw when AV_CLUB_TOKEN was unset. That is right for a service a person starts with a
shell and wrong for a sidecar the platform starts: not a safe default, a crash loop nobody sees. It
was exactly that — 15 restarts, every proxied request 503, and an error that named the files rather
than the missing variable.

Generating one loses nothing: authorised() already accepts the platform's X-Officer-User header with
no token at all, so no real caller carried this secret. It guards the direct loopback door, and 32
random bytes guard it better than a value copied into a shell profile. Kept 0600 beside the assets so
replacing the working tree does not change the service's identity.

AV_CLUB_TOKEN still wins when set. There is no unauthenticated mode; this only decides where the
token comes from.
2026-09-09 23:34:39 +01:00
..
2026-08-28 22:36:53 +01:00
2026-08-28 22:36:53 +01:00
2026-08-28 22:36:53 +01:00