From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f47.google.com (mail-wr1-f47.google.com [209.85.221.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7659D7F for ; Thu, 5 May 2022 23:16:31 +0000 (UTC) Received: by mail-wr1-f47.google.com with SMTP id d5so7891063wrb.6 for ; Thu, 05 May 2022 16:16:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paul-moore-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=BNb5FwciOrnmYbDhJp90kHEHFZ0681UtkEHiY9rBD84=; b=Ohr3X3EP78LxuYDKhnz8KuPiuz1PhY8VlacN2n0UZF33p11lrzHmoTg5FkuLveaWWc B+PHWzpGocOw99rYrrwOT2j6K7yl6TZjHfwiwfQv58T2SgC8RJjpZCrBvbUHRa3tAEjw vBvW2uixSk3X4wocsWWICUIdWEyFIPpXBQF7km3BjP4lO/AiOmnrqBvYof/Hmrk8g3Ui VsyTbQQECGTWGpH9GRnc/7V1pdbEyCgAuGzq4iO4E+9FajCsxUmBzSMnYaru+xQE/MDx VovhSYGTu5JLsFhCQL0rb2sLJwJC/ZTQ8Ao2n8UXvDJkacdd5/9qZgjSKryNtgTW6CEs aKmg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=BNb5FwciOrnmYbDhJp90kHEHFZ0681UtkEHiY9rBD84=; b=3vAHCIGragpmxG0Od6/KNyit3tAsHgfScjNlw08gGeeEEHNhDrbHpFgBHDk+WklLDO yyYnzQBed2Rn7arGbCrXOJK/Up7heb9Uez55SL7W/5uxkToeaDGcGPmvdAP1wgkJfFeN YRyrc2DXLlvnBWK0oVpx2jMgkiPy04xLpCJLi0ut3wVyp0xLx/J4F20/tslJxL3YUgko wh7ULC31qQQPl1xkQ0PoELarQgX/PUTymEHg/7TqdQhmXWp24RtNZECc/d9aGW1oNdXq CqyznvSDQ/In86JjRm/0XrhYIsC/GHG6XCquADUciBE9QxDW4RJosMSIRtRbtBKTE0Bs Bnsw== X-Gm-Message-State: AOAM530PLpnOCB7UCaCJVJEr3ASLkIwXERD6gGke6Zpo5dLjsv9fRQxL Yjrlv7gJoEnhBuGQtIcwryHlKSmjgVn1LxCOxq8o X-Google-Smtp-Source: ABdhPJyI6zIzqRKP45wkz/HSJ9ebgV2/QaH+Jh5XG21YfFQB+clnUfHaAanM4WnjOyZZ77zPKKT04iIWWkNblva8IBo= X-Received: by 2002:a5d:590d:0:b0:20a:c3eb:2584 with SMTP id v13-20020a5d590d000000b0020ac3eb2584mr325652wrd.18.1651792589559; Thu, 05 May 2022 16:16:29 -0700 (PDT) Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20220504014440.3697851-1-keescook@chromium.org> <20220504014440.3697851-29-keescook@chromium.org> <20220504234324.GA12556@embeddedor> <202205051124.6D80ABAE32@keescook> In-Reply-To: <202205051124.6D80ABAE32@keescook> From: Paul Moore Date: Thu, 5 May 2022 19:16:18 -0400 Message-ID: Subject: Re: [PATCH 28/32] selinux: Use mem_to_flex_dup() with xfrm and sidtab To: Kees Cook Cc: "Gustavo A. R. Silva" , Steffen Klassert , Herbert Xu , "David S. Miller" , Stephen Smalley , Eric Paris , Nick Desaulniers , Xiu Jianfeng , =?UTF-8?Q?Christian_G=C3=B6ttsche?= , netdev@vger.kernel.org, selinux@vger.kernel.org, Alexei Starovoitov , alsa-devel@alsa-project.org, Al Viro , Andrew Gabbasov , Andrew Morton , Andy Gross , Andy Lavr , Arend van Spriel , Baowen Zheng , Bjorn Andersson , Boris Ostrovsky , Bradley Grove , brcm80211-dev-list.pdl@broadcom.com, Christian Brauner , Christian Lamparter , Chris Zankel , Cong Wang , Daniel Axtens , Daniel Vetter , Dan Williams , David Gow , David Howells , Dennis Dalessandro , devicetree@vger.kernel.org, Dexuan Cui , Dmitry Kasatkin , Eli Cohen , Eric Dumazet , Eugeniu Rosca , Felipe Balbi , Francis Laniel , Frank Rowand , Franky Lin , Greg Kroah-Hartman , Gregory Greenman , Guenter Roeck , Haiyang Zhang , Hante Meuleman , Hulk Robot , Jakub Kicinski , "James E.J. Bottomley" , James Morris , Jarkko Sakkinen , Jaroslav Kysela , Jason Gunthorpe , Jens Axboe , Johan Hedberg , Johannes Berg , Johannes Berg , John Keeping , Juergen Gross , Kalle Valo , Keith Packard , keyrings@vger.kernel.org, kunit-dev@googlegroups.com, Kuniyuki Iwashima , "K. Y. Srinivasan" , Lars-Peter Clausen , Lee Jones , Leon Romanovsky , Liam Girdwood , linux1394-devel@lists.sourceforge.net, linux-afs@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-bluetooth@vger.kernel.org, linux-hardening@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-integrity@vger.kernel.org, linux-rdma@vger.kernel.org, linux-scsi@vger.kernel.org, linux-security-module@vger.kernel.org, linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org, linux-xtensa@linux-xtensa.org, llvm@lists.linux.dev, Loic Poulain , Louis Peens , Luca Coelho , Luiz Augusto von Dentz , Marc Dionne , Marcel Holtmann , Mark Brown , "Martin K. Petersen" , Max Filippov , Mimi Zohar , Muchun Song , Nathan Chancellor , =?UTF-8?B?TnVubyBTw6E=?= , Paolo Abeni , Rich Felker , Rob Herring , Russell King , "Serge E. Hallyn" , SHA-cyfmac-dev-list@infineon.com, Simon Horman , Stefano Stabellini , Stefan Richter , Stephen Hemminger , Tadeusz Struk , Takashi Iwai , Tom Rix , Udipto Goswami , Vincenzo Frascino , wcn36xx@lists.infradead.org, Wei Liu , xen-devel@lists.xenproject.org, Yang Yingliang Content-Type: text/plain; charset="UTF-8" On Thu, May 5, 2022 at 2:39 PM Kees Cook wrote: > On Wed, May 04, 2022 at 11:14:42PM -0400, Paul Moore wrote: > > On Wed, May 4, 2022 at 7:34 PM Gustavo A. R. Silva > > wrote: > > > > > > Hi Paul, > > > > > > On Wed, May 04, 2022 at 06:57:28PM -0400, Paul Moore wrote: > > > > On Tue, May 3, 2022 at 9:57 PM Kees Cook wrote: > > > > > > [..] > > > > > > > > +++ b/include/uapi/linux/xfrm.h > > > > > @@ -31,9 +31,9 @@ struct xfrm_id { > > > > > struct xfrm_sec_ctx { > > > > > __u8 ctx_doi; > > > > > __u8 ctx_alg; > > > > > - __u16 ctx_len; > > > > > + __DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(__u16, ctx_len); > > > > > __u32 ctx_sid; > > > > > - char ctx_str[0]; > > > > > + __DECLARE_FLEX_ARRAY_ELEMENTS(char, ctx_str); > > > > > }; > > > > > > > > While I like the idea of this in principle, I'd like to hear about the > > > > testing you've done on these patches. A previous flex array > > > > conversion in the audit uapi headers ended up causing a problem with > > > > > > I'm curious about which commit caused those problems...? > > > > Commit ed98ea2128b6 ("audit: replace zero-length array with > > flexible-array member"), however, as I said earlier, the problem was > > actually with SWIG, it just happened to be triggered by the kernel > > commit. There was a brief fedora-devel mail thread about the problem, > > see the link below: > > > > * https://www.spinics.net/lists/fedora-devel/msg297991.html > > Wow, that's pretty weird -- it looks like SWIG was scraping the headers > to build its conversions? I assume SWIG has been fixed now? I honestly don't know, the audit userspace was hacking around it with some header file duplication/munging last I heard, but I try to avoid having to touch Steve's audit userspace code. > > To reiterate, I'm supportive of changes like this, but I would like to > > hear how it was tested to ensure there are no unexpected problems with > > userspace. If there are userspace problems it doesn't mean we can't > > make changes like this, it just means we need to ensure that the > > userspace issues are resolved first. > > Well, as this is the first and only report of any problems with [0] -> [] > conversions (in UAPI or anywhere) that I remember seeing, and they've > been underway since at least v5.9, I hadn't been doing any new testing. ... and for whatever it is worth, I wasn't expecting it to be a problem either. Surprise :) > So, for this case, I guess I should ask what tests you think would be > meaningful here? Anything using #include should be fine: > https://codesearch.debian.net/search?q=linux%2Fxfrm.h&literal=1&perpkg=1 > Which leaves just this, which may be doing something weird: > > libabigail_2.0-1/tests/data/test-diff-filter/test-PR27569-v0.abi > > > > > > > But I see that SWIG doesn't show up in a search for linux/audit.h: > https://codesearch.debian.net/search?q=linux%2Faudit.h&literal=1&perpkg=1 > > So this may not be a sufficient analysis... I think from a practical perspective ensuring that the major IPsec/IKE tools, e.g. the various *SWANs, that know about labeled IPSec still build and can set/get the SA/SPD labels correctly would be sufficient. I seriously doubt there would be any problems, but who knows. -- paul-moore.com