From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from atuin.qyliss.net (localhost [IPv6:::1]) by atuin.qyliss.net (Postfix) with ESMTP id 126FD2AFB; Mon, 13 Jul 2026 11:12:01 +0000 (UTC) Received: by atuin.qyliss.net (Postfix, from userid 993) id 212452B1B; Mon, 13 Jul 2026 11:11:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on atuin.qyliss.net X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,DMARC_MISSING,RCVD_IN_DNSWL_LOW,SPF_HELO_PASS autolearn=unavailable autolearn_force=no version=4.0.1 Received: from fout-a5-smtp.messagingengine.com (fout-a5-smtp.messagingengine.com [103.168.172.148]) by atuin.qyliss.net (Postfix) with ESMTPS id C94082B19 for ; Mon, 13 Jul 2026 11:11:53 +0000 (UTC) Received: from phl-compute-11.internal (phl-compute-11.internal [10.202.2.51]) by mailfout.phl.internal (Postfix) with ESMTP id 27BDAEC0208; Mon, 13 Jul 2026 07:11:52 -0400 (EDT) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-11.internal (MEProxy); Mon, 13 Jul 2026 07:11:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alyssa.is; h=cc :cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:subject :subject:to:to; s=fm1; t=1783941112; x=1784027512; bh=Bgl7mEKEqb 7vfBRE0eKF7tQpEpcGyzUjNXGNse6hMwM=; b=W13FN/ZDIsq5gxemPDqcYdja2Y cn8tB9F7m9IiwOJKCBge6GUCIQUzIQxx5m04sj3ELzBDaIaYJ44/zRfX+49QqH4b wiGabJVUdo1s2SlikH//TgtIOV+vmruDakEug6Ls8CMlerV0kZpPXgZlwI33mB9L roF7KfcTM0NIiF+IR6H6sbXNQPcTlT4uDCokjR+biv2G246ptn7FhxA0CZ5I7V6A P5vi5Xxu0cjuanRx+31kJ7fySOGnRdpiaRmG0MfkDacYM38S1DAe1Kb88vwQCO3R tLlj89R/Lw37P1boRLxpDNxhoQNt7KeNEbt4CkKjWNnnRc4r1EffdiRMBBfQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; t= 1783941112; x=1784027512; bh=Bgl7mEKEqb7vfBRE0eKF7tQpEpcGyzUjNXG Nse6hMwM=; b=lGshdoY5XaOuXynOdQpC4CfaKX/TyfD8CUjnZ4X6PGB+T+zMyqx UBTsOT/ahhC7pJAiGvAGYCB5oKQUH/7NXadniga5RMusDTSarxHjMtYBg/OKzSkK yvFsDNciHu6F2ypgG5P6G7rEcNn+Fk6mGX13U0HyJhiQOMa8Kc2SbfNJ2jK1xQ9C SzCKNbRF314DO67TbM5vpqvTboDyGE5LZ5NkCaNa+v5PY2Bg8BhYu9qQgPqGvWIc cxNNQpXdS+aXBpp+c1aWUux3CMmWT63t0xRgtEhaZy5dgYDrVYL+zAQOCIZkOSgd c66xDsYm6zGqD4oINDIvlGlKK0PDgLtRM9w== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTGb9xMqHXYkxoYsmbi8oavNeeoyNKGD2cJSIuIFG5cAjyfGNJyHsuY/Qj64+rNf20 Qlvnkbaf8rvftFX+uZk9pCt5DXsgqGO9T77pa2dduQoiL8hhIH2Lr95KJynso/EKdX8inR ngAtJ8/Gcps+Pl2EU7oAtcXbOwzWS9VPr56pMkDX5tk8HyVyeQ/bbmKTKWI4i+AC+T/oGx fFep3IHOtnHeKWxhgg+xzMq3xkqsgBPtjtRPmMnc2g95ur2ePH06BtQmaDYXoUbIIZH+67 e1r1pahySmgSz/m4WNcee8oXFfd/PmXDujVJ4hw34EWozqE2KksO8/zslzN0NK1+V8hkQf pgekj28ieuGPcTzKhIcihv8tXs9ltphADXY1saGZ+YljQzkdmW71hwkcG5rnsIAG76G6vV iDL/6VF76IO14+aWy8ltRhhm8tDDM0FsWnWdIVhmHJpP9ASBCFdUKcGgwORGuObLCP89Da z2zSfrfsvMboXkHVNHBrbZXfmlcCEV1M7tXp4dmCky30Jni2R+TwA1BF/9u2/QM+BFsDTL hrV9wyKkc0y/XHlvccJYtKw3EPrAOxVB50xKAhNrlfIzsTizlwVXBqvO3akYIHYBBX9aoX frnHIwQA7DRcTEvxXkW8zaFp5GvNK45cXZ82WvcbVK8bVbGYU++7m6mgf9mA X-ME-Proxy: Feedback-ID: i12284293:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 13 Jul 2026 07:11:51 -0400 (EDT) Received: by mbp.qyliss.net (Postfix, from userid 1000) id 7C8D5890F497; Mon, 13 Jul 2026 11:04:37 +0200 (CEST) From: Alyssa Ross To: Demi Marie Obenour Subject: Re: Why is /run/vm/by-id/${VM} writable by the VMM? In-Reply-To: References: Date: Mon, 13 Jul 2026 11:04:36 +0200 Message-ID: <87ech71crf.fsf@alyssa.is> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Message-ID-Hash: U2HEZDVFALZOOFT7WG4JBWCQXR4RRQ4X X-Message-ID-Hash: U2HEZDVFALZOOFT7WG4JBWCQXR4RRQ4X X-MailFrom: hi@alyssa.is X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; header-match-devel.spectrum-os.org-0; header-match-devel.spectrum-os.org-1; header-match-devel.spectrum-os.org-2; header-match-devel.spectrum-os.org-3; header-match-devel.spectrum-os.org-4; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Spectrum OS Development X-Mailman-Version: 3.3.10 Precedence: list List-Id: Patches and low-level development discussion Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --=-=-= Content-Type: text/plain Demi Marie Obenour writes: > This seems to be a fairly significant hole in the VMM's sandbox. > Various code operates in that directory and isn't secure against > symlink attacks. > > Does the VMM really need write access to that directory? Could it > be given access to a subdirectory that is mounted "nosymfollow"? I think it's just so it can create e.g. the serial file. That could indeed be moved to a subdirectory. The ideal solution is of course for Cloud Hypervisor to be able to accept every file it would otherwise create as an open file descriptor, which I expect will happen eventually. --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQRV/neXydHjZma5XLJbRZGEIw/wogUCalSqJAAKCRBbRZGEIw/w oviGAP0Tgm3Aq/pfpsO7MU4ZJFmvJKZMGACXoKXaguuFVxFf6wEAgPOEdHYdOUk8 8laYMRwO1czUKb75PtDyd6+KNlgu6Qo= =Iw/P -----END PGP SIGNATURE----- --=-=-=--