We run `git rev-parse` though the shell, and quote its
argument only with single-quotes. This prevents most
metacharacters from being a problem, but misses the obvious
case when $name itself has single-quotes in it. We can fix
this by applying the usual shell-quoting formula.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refnames can contain shell metacharacters which need to be
passed verbatim to sub-processes. Using safe_pipe_capture
skips the shell entirely.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The git-cvsserver script is old and largely unmaintained
these days. But git-shell allows untrusted users to run it
out of the box, significantly increasing its attack surface.
Let's drop it from git-shell's list of internal handlers so
that it cannot be run by default. This is not backwards
compatible. But given the age and development activity on
CVS-related parts of Git, this is likely to impact very few
users, while helping many more (i.e., anybody who runs
git-shell and had no intention of supporting CVS).
There's no configuration mechanism in git-shell for us to
add a boolean and flip it to "off". But there is a mechanism
for adding custom commands, and adding CVS support here is
fairly trivial. Let's document it to give guidance to
anybody who really is still running cvsserver.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This makes the script pass arguments that are derived from end-user
input in safer way when invoking subcommands.
Reported-by: joernchen <joernchen@phenoelit.de>
Signed-off-by: joernchen <joernchen@phenoelit.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As a preparation for replacing `command` with a call to this
function from outside GITCVS::updater package, move it to the main
package.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If we get a repo path like "-repo.git", we may try to invoke
"git-upload-pack -repo.git". This is going to fail, since
upload-pack will interpret it as a set of bogus options. But
let's reject this before we even run the sub-program, since
we would not want to allow any mischief with repo names that
actually are real command-line options.
You can still ask for such a path via git-daemon, but there's no
security problem there, because git-daemon enters the repo itself
and then passes "." on the command line.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If you have a GIT_PROXY_COMMAND configured, we will run it
with the host/port on the command-line. If a URL contains a
mischievous host like "--foo", we don't know how the proxy
command may handle it. It's likely to break, but it may also
do something dangerous and unwanted (technically it could
even do something useful, but that seems unlikely).
We should err on the side of caution and reject this before
we even run the command.
The hostname check matches the one we do in a similar
circumstance for ssh. The port check is not present for ssh,
but there it's not necessary because the syntax is "-p
<port>", and there's no ambiguity on the parsing side.
It's not clear whether you can actually get a negative port
to the proxy here or not. Doing:
git fetch git://remote:-1234/repo.git
keeps the "-1234" as part of the hostname, with the default
port of 9418. But it's a good idea to keep this check close
to the point of running the command to make it clear that
there's no way to circumvent it (and at worst it serves as a
belt-and-suspenders check).
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We reject hostnames that start with a dash because they may
be confused for command-line options. Let's factor out that
notion into a helper function, as we'll use it in more
places. And while it's simple now, it's not clear if some
systems might need more complex logic to handle all cases.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Per the explanation in the previous patch, this should be
(and is) rejected.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When commands like "git fetch" talk with ssh://$rest_of_URL/, the
code splits $rest_of_URL into components like host, port, etc., and
then spawns the underlying "ssh" program by formulating argv[] array
that has:
- the path to ssh command taken from GIT_SSH_COMMAND, etc.
- dashed options like '-batch' (for Tortoise), '-p <port>' as
needed.
- ssh_host, which is supposed to be the hostname parsed out of
$rest_of_URL.
- then the command to be run on the other side, e.g. git
upload-pack.
If the ssh_host ends up getting '-<anything>', the argv[] that is
used to spawn the command becomes something like:
{ "ssh", "-p", "22", "-<anything>", "command", "to", "run", NULL }
which obviously is bogus, but depending on the actual value of
"<anything>", will make "ssh" parse and use it as an option.
Prevent this by forbidding ssh_host that begins with a "-".
Noticed-by: Joern Schneeweisz of Recurity Labs
Reported-by: Brian at GitLab
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a remote server uses git-shell, the client side will
connect to it like:
ssh server "git-upload-pack 'foo.git'"
and we literally exec ("git-upload-pack", "foo.git"). In
early versions of upload-pack and receive-pack, we took a
repository argument and nothing else. But over time they
learned to accept dashed options. If the user passes a
repository name that starts with a dash, the results are
confusing at best (we complain of a bogus option instead of
a non-existent repository) and malicious at worst (the user
can start an interactive pager via "--help").
We could pass "--" to the sub-process to make sure the
user's argument is interpreted as a branch name. I.e.:
git-upload-pack -- -foo.git
But adding "--" automatically would make us inconsistent
with a normal shell (i.e., when git-shell is not in use),
where "-foo.git" would still be an error. For that case, the
client would have to specify the "--", but they can't do so
reliably, as existing versions of git-shell do not allow
more than a single argument.
The simplest thing is to simply disallow "-" at the start of
the repo name argument. This hasn't worked either with or
without git-shell since version 1.0.0, and nobody has
complained.
Note that this patch just applies to do_generic_cmd(), which
runs upload-pack, receive-pack, and upload-archive. There
are two other types of commands that git-shell runs:
- do_cvs_cmd(), but this already restricts the argument to
be the literal string "server"
- admin-provided commands in the git-shell-commands
directory. We'll pass along arbitrary arguments there,
so these commands could have similar problems. But these
commands might actually understand dashed arguments, so
we cannot just block them here. It's up to the writer of
the commands to make sure they are safe. With great
power comes great responsibility.
Reported-by: Timo Schmid <tschmid@ernw.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Typing ^C to pager, which usually does not kill it, killed Git and
took the pager down as a collateral damage in certain process-tree
structure. This has been fixed.
* jk/execv-dashed-external:
execv_dashed_external: wait for child on signal death
execv_dashed_external: stop exiting with negative code
execv_dashed_external: use child_process struct
