Re: [PATCH] tftpd: strip leading slashes from the requested file name

Guillermo Rodriguez Garcia via busybox <[email protected]>
Newsgroups gmane.linux.busybox
Message-ID <CABDcavZRxGiO5YF-PgOkAe4C4vN5Hugon=cn9sSrnjJf_Vrg2Q@mail.gmail.com>
El mar, 18 ago 2026 a las 9:10, Ali Ahmet Memis (<[email protected]>) escribió:
>
> tftpd-hpa's model needs a list of directories to validate an absolute
> path against. BusyBox tftpd does not currently have such an allowlist
> model. DIR just chroots into a single directory, nothing else.
>
> I went back to bug 4874, the one this patch closes. The reporter's
> own expected behavior was: absolute path translated to the tftpd dir
> (/vmlinuz -> /boot/vmlinuz), or rejected if it falls outside. That's
> stripping, not reject, not validate-against-a-list.

That may be the reporter's expectation but that does not necessarily
mean it's the right thing to do.

The reporter's needs can be easily met by just passing /boot as a DIR.

Your patch is equivalent to assuming "if not DIR is given, behave
exactly as if DIR=<cwd>" was specified. I am not sure this should be
the case.

Guillermo Rodriguez Garcia
[email protected]
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