phpman > man > gitnamespaces(7)

GITNAMESPACES(7)                             Git Manual                             GITNAMESPACES(7)



NAME
       gitnamespaces - Git namespaces

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


DESCRIPTION
       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
       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
       Part of the git(1) suite



Git 2.34.1                                   02/26/2026                             GITNAMESPACES(7)