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¶
Anyone with access to any namespace within a repository can potentially access
objects from any other namespace stored in the same repository. You
can’t directly say "give me object ABCD" if you don’t
have a ref to it, but you can do some other sneaky things like:
1.Claiming to push ABCD, at which point the
server will optimize out the need for you to actually send it. Now you have a
ref to ABCD and can fetch it (claiming not to have it, of course).
2.Requesting other refs, claiming that you
have ABCD, at which point the server may generate deltas against ABCD.
None of this causes a problem if you only host public repositories, or if
everyone who may read one namespace may also read everything in every other
namespace (for instance, if everyone in an organization has read permission to
every repository).