gitnamespaces(7) — Linux manual page

NAME \| SYNOPSIS \| DESCRIPTION \| SECURITY \| GIT \| 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.

GIT top

       Part of the git(1) suite

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 2025-08-11.  (At that time,
       the date of the most recent commit that was found in the
       repository was 2025-08-07.)  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 2.51.0.rc1                  2025-08-07               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)