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Tue, 29 Mar 2022 12:46:10 -0700 (PDT) Received: from [10.0.0.2] ([162.156.254.107]) by smtp.gmail.com with ESMTPSA id n143-20020a37a495000000b0067b12bc1d7bsm9971750qke.13.2022.03.29.12.46.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Mar 2022 12:46:10 -0700 (PDT) Message-ID: Date: Tue, 29 Mar 2022 15:46:09 -0400 List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Content-Language: en-US To: Shawn Webb Cc: freebsd-hackers@FreeBSD.org References: <25b5c60f-b9cc-78af-86d7-1cc714232364@gmail.com> <20220329181428.n3db2x57nnn64yfx@mutt-hbsd> From: Mathieu Subject: Re: curtain: WIP sandboxing mechanism with pledge()/unveil() support In-Reply-To: <20220329181428.n3db2x57nnn64yfx@mutt-hbsd> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 4KSg6W3W7Mz57N6 X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20210112 header.b=OJ6XGQBb; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of sigsys@gmail.com designates 2607:f8b0:4864:20::f2b as permitted sender) smtp.mailfrom=sigsys@gmail.com X-Spamd-Result: default: False [-4.00 / 15.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36:c]; FREEMAIL_FROM(0.00)[gmail.com]; RCVD_COUNT_THREE(0.00)[3]; DKIM_TRACE(0.00)[gmail.com:+]; RCPT_COUNT_TWO(0.00)[2]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; NEURAL_HAM_SHORT(-1.00)[-1.000]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; MID_RHS_MATCH_FROM(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-0.998]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20210112]; FROM_HAS_DN(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[2607:f8b0:4864:20::f2b:from]; MLMMJ_DEST(0.00)[freebsd-hackers]; RCVD_TLS_ALL(0.00)[] X-ThisMailContainsUnwantedMimeParts: N On 3/29/22 14:14, Shawn Webb wrote: > On Mon, Mar 28, 2022 at 05:37:44AM -0400, Mathieu wrote: >> Hello list.  Since a while I've been working on and off on a >> pledge()/unveil() implementation for FreeBSD.  I also wanted it to be able >> to sandbox arbitrary programs that might not expect it with no (or very >> minor) modifications.  So I just kept adding to it until it could do that >> well enough.  I'm still working on it, and there are some known issues and >> some things I'm not sure are done correctly, but overall it's in a very >> functional state now. It can run unmodified most utilities and desktop apps >> (though dbus/dconf/etc are trouble), server daemons, buildworld and whole >> shell/desktop sessions sandboxed. >> >> https://github.com/Math2/freebsd-pledge >> https://github.com/Math2/freebsd-pledge/blob/main/CURTAIN-README.md >> >> It can be broken up in 4 parts: 1) A MAC module that implements most of the >> functionality.  2) The userland library, sandboxing utility, configs and >> tests.  3) Various kernel changes needed to support it (including new MAC >> handlers and extended syscall filtering).  4) Small changes/fixes to the >> base userland (things like adding reporting to ps and modifying some >> utilities to use $TMPDIR so that they can be properly sandboxed).  So 1) and >> 2) could be in a port.  And I tried to minimize 3) and 4) as much as >> possible. >> >> I noted some problems/limitations in the CURTAIN-ISSUES file.  At this point >> I'm mostly wondering about the general design being acceptable for merging >> eventually.  Because most of this could be part of a port, but not all of >> it.  And the way that it deals with filesystem access restrictions in >> particular is kludgy.  So any feedback/testing welcome. >> >> It still lacks documentation (in part because I'm not sure of what could >> still change) so I'm going to give an overview of it here and show some >> examples and that's going to be the documentation for now.  And I'll >> describe the kernel changes that it needed.  So that's going to be a bit of >> a long email. > Hey Mathieu, > > Thanks a lot for working on this! I'm incredibly excited to see this > work progress and mature. Hey! Thanks, nice to hear that. > I'd love to start reviewing your work. One thing that would make it > easier to review would be if you used a feature branch rather than > relying on the main branch. That way, a simple `git diff` command > could be used to generate a diff between your code and stock freebsd. > > If you'd like an example of that, take a look at HardenedBSD's > repo[0]. We have two relevant branches: > > freebsd/current/main <- FreeBSD's sources > hardened/current/main <- HardenedBSD's patches applied on top of > FreeBSD's sources > > Users can then simply run `git diff origin/freebsd/current/main` to > see all the changes we've made (assuming the user is currently working > on the hardened/current/master branch.) > > [0]: https://git.hardenedbsd.org/HardenedBSD/hardenedbsd I gotta be honest, I'm never too sure if I understand what git is doing. So I try to keep it simple. I'm going to create a "stock" branch and keep it pointing *exactly* to what I've been merging from. Lemme know if that works. I'm not too sure I'd be using a more elaborate branch layout correctly... This is going to be a lot of work to review so yeah I'd try to set this up to make it easier but I could just make it worse too heh. The way I've been comparing my changes to stock so far was with 3 dots diff: `git diff freebsd/main...main`. Also, I gotta warn you, the lack of comments is just terrible in some places. This project turned out to be a lot more complicated than I had hoped. Correctly handling "slots" and inheritance/masking between sandboxes was harder than I thought. Most of the complexity are in the library and MAC module. But I think it probably was necessary complexity to get the (mostly) seamlessly nestable sandboxing system that I wanted... > > Thanks, >