From: Taylor Blau <firstname.lastname@example.org> To: Emily Shaffer <email@example.com> Cc: "Taylor Blau" <firstname.lastname@example.org>, "Glen Choo" <email@example.com>, "Git List" <firstname.lastname@example.org>, email@example.com, "Johannes Schindelin" <Johannes.Schindelin@gmx.de>, "Ævar Arnfjörð Bjarmason" <firstname.lastname@example.org>, "Derrick Stolee" <email@example.com>, "Junio C Hamano" <firstname.lastname@example.org>, "brian m. carlson" <email@example.com>, "Randall S. Becker" <firstname.lastname@example.org> Subject: Re: Bare repositories in the working tree are a security risk Date: Thu, 21 Apr 2022 15:09:06 -0400 [thread overview] Message-ID: <YmGr0upicQJML+9B@nand.local> (raw) In-Reply-To: <CAJoAoZkgnnvdymuBsM9Ja3+eYSnyohr=FQZMVX_uzZ_pkQhgaw@mail.gmail.com> On Thu, Apr 21, 2022 at 11:25:39AM -0700, Emily Shaffer wrote: > On Fri, Apr 15, 2022 at 6:28 PM Taylor Blau <email@example.com> wrote: > > > > On Fri, Apr 15, 2022 at 05:41:59PM -0700, Glen Choo wrote: > > > * We want additional protection on the client besides `git fsck`; there are > > > a few ways to do this: > > > > I'm a little late to chime into the thread, but I appreciate you > > summarizing some of the approaches discussed so far. Let me add my > > thoughts on each of these in order: > > > > > 1. Prevent checking out an embedded bare repo. > > > 2. Detect if the bare repo is embedded and refuse to work with it. > > > 3. Detect if the bare repo is embedded and do not read its config/hooks, but > > > everything else still 'works'. > > > 4. Don't detect bare repos. > > > 5. Only detect bare repos that are named `.git` . > > > > > > (I've responded with my thoughts on each of these approaches in-thread). > > > > 1. Likely disrupts too many legitimate workflows for us to adopt > > without designing some way to declare an embedded bare repository > > is "safe". > > 2. Ditto. > > 3. This seems the most promising approach so far. Similar to (1), I > > would also want to make sure we provide an easy way to declare a > > bare repository as "safe" in order to avoid permanently disrupting > > valid workflows that have accumulated over the past >15 years. > > I'd like to think a little more about how we want to determine that a > bare repo isn't embedded - wantonly scanning up the filesystem for any > gitdir above the current one is really expensive. When I tried that > approach for the purposes of including some shared config between > superproject and submodules, it slowed down the Git test suite by > something like 3-5x. So, I suppose that "we think this is bare" means > refs/ and objects/ present in a directory that isn't named '.git/', > and then we hunt anywhere above us for another .git/? Of course being > careful not to accept another bare repo as the "parent" gitdir. Definitely worth considering. Fundamentally I think if you're going to allow checking out embedded bare repositories (which I strongly think that we should), any search for "is this repository embedded in another one?" needs to walk along its entire path up to the filesystem root. I'd think that we could offer some tools, perhaps "safe.boundary", specifying a list of directories to halt our traversal at. IOW, if you have a bunch of bare repositories underneath /data/repositories, and know that they're all safe, you could set your boundary there to signal to Git "if my path is a subdirectory of anything in safe.boundary, then I don't care whether the repo is embedded or not". > Does it work for submodules? I suppose it works for non-bare > submodules - and for bare submodules, e.g. > 'submodule-having-project.git/modules/some-submodule/' we can rely on > the user to turn that flag on if they want their submodule's config > and hooks to be noticed from the gitdir. (From > 'worktree-for-submodule-having-project/some-submodule' there is a > '.git' pointer, so I'd expect things to work normally that way, > right?) I don't enough about submodules to comment here, sorry. > > Here's an alternative approach, which I haven't seen discussed thus > > far: [...] > > Nice - a more strict spin on proposal 3 from above, if I understand it > right. Rather than allowing any and all bare repos, avoid someone > sneaking in a malicious one next to legitimate ones by using an > allowlist. Seems reasonable to me. We'd probably want to allow saying "all embedded bare repositories are safe to read config/hooks from", too. I hadn't considered this approach as a way to read some embedded repos and not others; I suspect the overwhelmingly common use-case would be: `git config --local safe.embeddedRepo '*'`. Thanks, Taylor
next prev parent reply other threads:[~2022-04-21 19:09 UTC|newest] Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-04-06 22:43 Glen Choo 2022-04-06 23:22 ` [PATCH] fsck: detect bare repos in trees and warn Glen Choo 2022-04-07 12:42 ` Johannes Schindelin 2022-04-07 13:21 ` Derrick Stolee 2022-04-07 14:14 ` Ævar Arnfjörð Bjarmason 2022-04-14 20:02 ` Glen Choo 2022-04-15 12:46 ` Ævar Arnfjörð Bjarmason 2022-04-07 15:11 ` Junio C Hamano 2022-04-13 22:24 ` Glen Choo 2022-04-07 13:12 ` Ævar Arnfjörð Bjarmason 2022-04-07 15:20 ` Junio C Hamano 2022-04-07 18:38 ` Bare repositories in the working tree are a security risk John Cai 2022-04-07 21:24 ` brian m. carlson 2022-04-07 21:53 ` Justin Steven 2022-04-07 22:10 ` brian m. carlson 2022-04-07 22:40 ` rsbecker 2022-04-08 5:54 ` Junio C Hamano 2022-04-14 0:03 ` Junio C Hamano 2022-04-14 0:04 ` Glen Choo 2022-04-13 23:44 ` Glen Choo 2022-04-13 20:37 ` Glen Choo 2022-04-13 23:36 ` Junio C Hamano 2022-04-14 16:41 ` Glen Choo 2022-04-14 17:35 ` Junio C Hamano 2022-04-14 18:19 ` Junio C Hamano 2022-04-15 21:33 ` Glen Choo 2022-04-15 22:17 ` Junio C Hamano 2022-04-16 0:52 ` Taylor Blau 2022-04-15 22:43 ` Glen Choo 2022-04-15 20:13 ` Junio C Hamano 2022-04-15 23:45 ` Glen Choo 2022-04-15 23:59 ` Glen Choo 2022-04-16 1:00 ` Taylor Blau 2022-04-16 1:18 ` Junio C Hamano 2022-04-16 1:30 ` Taylor Blau 2022-04-16 0:34 ` Glen Choo 2022-04-16 0:41 ` Glen Choo 2022-04-16 1:28 ` Taylor Blau 2022-04-21 18:25 ` Emily Shaffer 2022-04-21 18:29 ` Emily Shaffer 2022-04-21 18:47 ` Junio C Hamano 2022-04-21 18:54 ` Taylor Blau 2022-04-21 19:09 ` Taylor Blau [this message] 2022-04-21 21:01 ` Emily Shaffer 2022-04-21 21:22 ` Taylor Blau 2022-04-29 23:57 ` Glen Choo 2022-04-30 1:14 ` Taylor Blau 2022-05-02 19:39 ` Glen Choo 2022-05-02 14:05 ` Philip Oakley 2022-05-02 18:50 ` Junio C Hamano
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=YmGr0upicQJML+9B@nand.local \ --firstname.lastname@example.org \ --cc=Johannes.Schindelin@gmx.de \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --subject='Re: Bare repositories in the working tree are a security risk' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).