gitnamespaces(7) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | SECURITY | COLOPHON

GITNAMESPACES(7)               Git Manual               GITNAMESPACES(7)

NAME         top

       gitnamespaces - Git namespaces

SYNOPSIS         top

       GIT_NAMESPACE=<namespace> git upload-pack
       GIT_NAMESPACE=<namespace> git receive-pack

DESCRIPTION         top

       Git supports dividing the refs of a single repository into
       multiple namespaces, each of which has its own branches, tags,
       and HEAD. Git can expose each namespace as an independent
       repository to pull from and push to, while sharing the object
       store, and exposing all the refs to operations such as git-gc(1).

       Storing multiple repositories as namespaces of a single
       repository avoids storing duplicate copies of the same objects,
       such as when storing multiple branches of the same source. The
       alternates mechanism provides similar support for avoiding
       duplicates, but alternates do not prevent duplication between new
       objects added to the repositories without ongoing maintenance,
       while namespaces do.

       To specify a namespace, set the GIT_NAMESPACE environment
       variable to the namespace. For each ref namespace, Git stores the
       corresponding refs in a directory under refs/namespaces/. For
       example, GIT_NAMESPACE=foo will store refs under
       refs/namespaces/foo/. You can also specify namespaces via the
       --namespace option to git(1).

       Note that namespaces which include a / will expand to a hierarchy
       of namespaces; for example, GIT_NAMESPACE=foo/bar will store refs
       under refs/namespaces/foo/refs/namespaces/bar/. This makes paths
       in GIT_NAMESPACE behave hierarchically, so that cloning with
       GIT_NAMESPACE=foo/bar produces the same result as cloning with
       GIT_NAMESPACE=foo and cloning from that repo with
       GIT_NAMESPACE=bar. It also avoids ambiguity with strange
       namespace paths such as foo/refs/heads/, which could otherwise
       generate directory/file conflicts within the refs directory.

       git-upload-pack(1) and git-receive-pack(1) rewrite the names of
       refs as specified by GIT_NAMESPACE. git-upload-pack and
       git-receive-pack will ignore all references outside the specified
       namespace.

       The smart HTTP server, git-http-backend(1), will pass
       GIT_NAMESPACE through to the backend programs; see
       git-http-backend(1) for sample configuration to expose repository
       namespaces as repositories.

       For a simple local test, you can use git-remote-ext(1):

           git clone ext::'git --namespace=foo %s /tmp/prefixed.git'

SECURITY         top

       The fetch and push protocols are not designed to prevent one side
       from stealing data from the other repository that was not
       intended to be shared. If you have private data that you need to
       protect from a malicious peer, your best option is to store it in
       another repository. This applies to both clients and servers. In
       particular, namespaces on a server are not effective for read
       access control; you should only grant read access to a namespace
       to clients that you would trust with read access to the entire
       repository.

       The known attack vectors are as follows:

        1. The victim sends "have" lines advertising the IDs of objects
           it has that are not explicitly intended to be shared but can
           be used to optimize the transfer if the peer also has them.
           The attacker chooses an object ID X to steal and sends a ref
           to X, but isn’t required to send the content of X because the
           victim already has it. Now the victim believes that the
           attacker has X, and it sends the content of X back to the
           attacker later. (This attack is most straightforward for a
           client to perform on a server, by creating a ref to X in the
           namespace the client has access to and then fetching it. The
           most likely way for a server to perform it on a client is to
           "merge" X into a public branch and hope that the user does
           additional work on this branch and pushes it back to the
           server without noticing the merge.)

        2. As in #1, the attacker chooses an object ID X to steal. The
           victim sends an object Y that the attacker already has, and
           the attacker falsely claims to have X and not Y, so the
           victim sends Y as a delta against X. The delta reveals
           regions of X that are similar to Y to the attacker.

COLOPHON         top

       This page is part of the git (Git distributed version control
       system) project.  Information about the project can be found at
       ⟨http://git-scm.com/⟩.  If you have a bug report for this manual
       page, see ⟨http://git-scm.com/community⟩.  This page was obtained
       from the project's upstream Git repository
       ⟨https://github.com/git/git.git⟩ on 2021-04-01.  (At that time,
       the date of the most recent commit that was found in the
       repository was 2021-03-30.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

Git 2.31.1.163.ga65ce7         04/01/2021               GITNAMESPACES(7)

Pages that refer to this page: git(1)git-config(1)git-http-backend(1)git-receive-pack(1)git-upload-pack(1)