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
       2017-03-13.  If you discover any rendering problems in this HTML ver‐
       sion 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 man‐
       ual page), send a mail to man-pages@man7.org

Git 2.12.0.rc2                   02/18/2017                 GITNAMESPACES(7)