Re: [PATCH v20 43/48] refs.c: move the check for valid refname to lock_ref_sha1_basic

On Wed, Aug 20, 2014 at 10:49 AM, Jonathan Nieder [off-list ref] wrote:

Hi,

Ronnie Sahlberg wrote:

quoted

On Wed, Aug 20, 2014 at 7:52 AM, Michael Haggerty [off-list ref] wrote:

quoted

quoted

I'm a little worried that abandoning *all* refname checks could open us
up to somehow trying to delete a "reference" with a name like
"../../../../etc/passwd".  Either such names have to be prohibited
somehow, or we have to be very sure that they can only come from trusted
sources.

I only set this flag from builtin/branch.c so it should only be used
when a user runs 'git branch -D' from the command line.
All other places where we delete branches we should still be checking
the rename for badness.

Right, this should be safe for 'git branch -D' and 'git update-ref -d'.

But if we wanted to open it up in the future for 'git push --delete',
too, then it would be a way to break out of the repository on hosts where
people use git-shell instead of relying on filesystem permissions.  And
that wouldn't be good.

I think elsewhere git has some checks for "does this pathname fall in
this directory".  Could that be reused here, too, to make sure the
resolved path is under the resolved $GIT_DIR/refs directory?

Alternatively, when a ref being deleted doesn't meet the
'check-ref-format' checks, would it make sense to check that it is one
of the refs you can get by iteration?

Good idea! I will add such a check using the iterator.
That means that "we can git branch -D anything that shows up in the
iterator regardless if the ref is badly named or unresolvable" which
sounds like fairly sane semantics.

Thanks!

Ronnie