From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57965C28CC2 for ; Wed, 29 May 2019 15:54:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 30DE323C80 for ; Wed, 29 May 2019 15:54:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="qADd6C9d" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727120AbfE2Pxy (ORCPT ); Wed, 29 May 2019 11:53:54 -0400 Received: from sonic303-8.consmr.mail.bf2.yahoo.com ([74.6.131.47]:33479 "EHLO sonic303-8.consmr.mail.bf2.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727015AbfE2Pxx (ORCPT ); Wed, 29 May 2019 11:53:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1559145231; bh=Mhbbs/5zWDmSATWlWIaWSZbJKp7jJqyJaP5TnNMG0Cw=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From:Subject; b=qADd6C9dYyk8KS/JPMsgMG4dSY02lpjCx3eUrn3i8pPoaQZwpwXVOaljGU9u5kB8KHIYPQa9JunT+waccGB55AKFbHuWiQXTLZPfIlOsadSGQWce4R8t5X7yVT3Rxip9j60HgY+G4hVU3/ptICnzlwewJdUkeCaLXNcJJudrHcriKspDKrN/fRDCSfJZJxcWAlh2zFp/FbyZWxtxga81R18kPHV40pfSas4Eu3B2eQXvV/+WBdnIHxzmM02R7fh3D6S+Vo5PtUv1AXp9otJfWz/Kq6PtblUogqiSycCv9a6L69ORe4P0PEPC8X9UQ7t3AGD64udX3VEdir3jGwPH7Q== X-YMail-OSG: un8.J_sVM1kuGbHsYEm81uJHc1EgIo3WEUPpoKRMD88B4ckPYjIHzzu3KeSb98x Y5EsfcoCL8aaVWM26Xw4_KyP7tHf4ADBTaZPve5fZb2A91v0VuJ2Kk69t_rEFAk0iOMX7Z__Nyqt qAYNOQ7nhEXahnndv8QX45sGkCWwQpISHuw5nseb9UJMLc.FZHo6lVuMzEa.z41Yc.nlOfeF9LFT iG.NFhIMHl8fUhT9rxrvPwQWvJng0prtB920ojYer9ZUQwbpkhxa6BAATZubuY_BsqHtWi36waxq xfLOnA2RQ5x6Xd54IUTW8SOY8NPAegET5HYrnH2IrO89lYEpDlyDTPW2AMMabjzLVO_J5Mlzq99L I5vSBMEVOg9pJ4V.1sFjb0duC3SlbU5vTrQBDfVWWYjgUtwP1SRhCDyjKFxUQ2YxOBEh.XwyxYfU BKM41k33feB1SUQ4024vbWRSpTnCjx63UtxLNIdrlxv23VsO4SGgzX28APdEzu6XLw4.hQ0WD1WC mDswysk_zaD0uWc3z_Ff6jgCgyL.BgAUSEZs59scWzUdY0bYejhQYRc9nw43sNuKmtowK1C.rSUA BgAdyCN008k0cKyycfH0l91VvYMu6SixXnrLGlxnnwzx1AEpu9PFlfreiAP52iEzC9Rq53BAMZPm W6wiIe6hxOQ9KtA9HTqpHBaqj6wB_aF3KadJUr96rma1EARmY2b5L2oRG65h_E5HzGXM0ZblRc6J UW4h12ANx4CbV6mKSI_2cc0VV.y.TmAZe5VMG8pwIhYahKotMruLPZpfC.iw7BeReEsyTxzjpykW iC0bWqgm6tPwgbFHwiwm5mvH9z1GAMwdKYevY2GsZHqul2auRN5sYDzHp84kOK1WI7XpTndmJWWe KZOFTdqexV20nvXFEQ8PE0LeK.bjAmHvNwVoKuIiK.PV14pYo_G2SuNRSvYLJ3nhOwW.Y2hx6iZL uIkmj9ZaCEHEdFh0EZHvnY7BoZFTkC2_Dw4mQZ5JDZ_GXOpzoUqK1E0n8NufYZIJ0iB7GMHHS7tW Dp8KhOPlS9WCtb_vXu0v7GLez3rS9Qv8W14odbSUUBpPbCmTBY5hqlaY3kPwBCK5uBzxN5C3wly2 Sl75ILGM34._zWV818b0wwUVtYf692GLllUWrHdN1WZf.Ad3NxwLrBv8kAeRnUCjohfWVyxZqe93 Yj5UeurORKiMUBmXBc2Wja6QWyR0bvHk5BbvMIwgY7A0C._nmVF9mZxJH9tT3jpJwIjPFfQOhM18 mJOFCgs_8nJ2ch1wn6DSN4AE1IiERihrII.S3iQ-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic303.consmr.mail.bf2.yahoo.com with HTTP; Wed, 29 May 2019 15:53:51 +0000 Received: from c-73-223-4-185.hsd1.ca.comcast.net (EHLO [192.168.0.103]) ([73.223.4.185]) by smtp410.mail.bf1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID 9da4e0a2a8856f6c7fc42e042e64d391; Wed, 29 May 2019 15:53:47 +0000 (UTC) Subject: Re: [PATCH 3/7] vfs: Add a mount-notification facility To: David Howells , Jann Horn Cc: Al Viro , raven@themaw.net, linux-fsdevel , Linux API , linux-block@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module , kernel list References: <155905930702.7587.7100265859075976147.stgit@warthog.procyon.org.uk> <155905933492.7587.6968545866041839538.stgit@warthog.procyon.org.uk> <14347.1559127657@warthog.procyon.org.uk> From: Casey Schaufler Openpgp: preference=signencrypt Autocrypt: addr=casey@schaufler-ca.com; keydata= mQINBFzV9HABEAC/mmv3jeJyF7lR7QhILYg1+PeBLIMZv7KCzBSc/4ZZipoWdmr77Lel/RxQ 1PrNx0UaM5r6Hj9lJmJ9eg4s/TUBSP67mTx+tsZ1RhG78/WFf9aBe8MSXxY5cu7IUwo0J/CG vdSqACKyYPV5eoTJmnMxalu8/oVUHyPnKF3eMGgE0mKOFBUMsb2pLS/enE4QyxhcZ26jeeS6 3BaqDl1aTXGowM5BHyn7s9LEU38x/y2ffdqBjd3au2YOlvZ+XUkzoclSVfSR29bomZVVyhMB h1jTmX4Ac9QjpwsxihT8KNGvOM5CeCjQyWcW/g8LfWTzOVF9lzbx6IfEZDDoDem4+ZiPsAXC SWKBKil3npdbgb8MARPes2DpuhVm8yfkJEQQmuLYv8GPiJbwHQVLZGQAPBZSAc7IidD2zbf9 XAw1/SJGe1poxOMfuSBsfKxv9ba2i8hUR+PH7gWwkMQaQ97B1yXYxVEkpG8Y4MfE5Vd3bjJU kvQ/tOBUCw5zwyIRC9+7zr1zYi/3hk+OG8OryZ5kpILBNCo+aePeAJ44znrySarUqS69tuXd a3lMPHUJJpUpIwSKQ5UuYYkWlWwENEWSefpakFAIwY4YIBkzoJ/t+XJHE1HTaJnRk6SWpeDf CreF3+LouP4njyeLEjVIMzaEpwROsw++BX5i5vTXJB+4UApTAQARAQABtChDYXNleSBTY2hh dWZsZXIgPGNhc2V5QHNjaGF1Zmxlci1jYS5jb20+iQJUBBMBCAA+FiEEC+9tH1YyUwIQzUIe OKUVfIxDyBEFAlzV9HACGwMFCRLMAwAFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AACgkQOKUV fIxDyBG6ag/6AiRl8yof47YOEVHlrmewbpnlBTaYNfJ5cZflNRKRX6t4bp1B2YV1whlDTpiL vNOwFkh+ZE0eI5M4x8Gw2Oiok+4Q5liA9PHTozQYF+Ia+qdL5EehfbLGoEBqklpGvG3h8JsO 7SvONJuFDgvab/U/UriDYycJwzwKZuhVtK9EMpnTtUDyP3DY+Q8h7MWsniNBLVXnh4yBIEJg SSgDn3COpZoFTPGKE+rIzioo/GJe8CTa2g+ZggJiY/myWTS3quG0FMvwvNYvZ4I2g6uxSl7n bZVqAZgqwoTAv1HSXIAn9muwZUJL03qo25PFi2gQmX15BgJKQcV5RL0GHFHRThDS3IyadOgK P2j78P8SddTN73EmsG5OoyzwZAxXfck9A512BfVESqapHurRu2qvMoUkQaW/2yCeRQwGTsFj /rr0lnOBkyC6wCmPSKXe3dT2mnD5KnCkjn7KxLqexKt4itGjJz4/ynD/qh+gL7IPbifrQtVH JI7cr0fI6Tl8V6efurk5RjtELsAlSR6fKV7hClfeDEgLpigHXGyVOsynXLr59uE+g/+InVic jKueTq7LzFd0BiduXGO5HbGyRKw4MG5DNQvC//85EWmFUnDlD3WHz7Hicg95D+2IjD2ZVXJy x3LTfKWdC8bU8am1fi+d6tVEFAe/KbUfe+stXkgmfB7pxqW5Ag0EXNX0cAEQAPIEYtPebJzT wHpKLu1/j4jQcke06Kmu5RNuj1pEje7kX5IKzQSs+CPH0NbSNGvrA4dNGcuDUTNHgb5Be9hF zVqRCEvF2j7BFbrGe9jqMBWHuWheQM8RRoa2UMwQ704mRvKr4sNPh01nKT52ASbWpBPYG3/t WbYaqfgtRmCxBnqdOx5mBJIBh9Q38i63DjQgdNcsTx2qS7HFuFyNef5LCf3jogcbmZGxG/b7 yF4OwmGsVc8ufvlKo5A9Wm+tnRjLr/9Mn9vl5Xa/tQDoPxz26+aWz7j1in7UFzAarcvqzsdM Em6S7uT+qy5jcqyuipuenDKYF/yNOVSNnsiFyQTFqCPCpFihOnuaWqfmdeUOQHCSo8fD4aRF emsuxqcsq0Jp2ODq73DOTsdFxX2ESXYoFt3Oy7QmIxeEgiHBzdKU2bruIB5OVaZ4zWF+jusM Uh+jh+44w9DZkDNjxRAA5CxPlmBIn1OOYt1tsphrHg1cH1fDLK/pDjsJZkiH8EIjhckOtGSb aoUUMMJ85nVhN1EbU/A3DkWCVFEA//Vu1+BckbSbJKE7Hl6WdW19BXOZ7v3jo1q6lWwcFYth esJfk3ZPPJXuBokrFH8kqnEQ9W2QgrjDX3et2WwZFLOoOCItWxT0/1QO4ikcef/E7HXQf/ij Dxf9HG2o5hOlMIAkJq/uLNMvABEBAAGJAjwEGAEIACYWIQQL720fVjJTAhDNQh44pRV8jEPI EQUCXNX0cAIbDAUJEswDAAAKCRA4pRV8jEPIEWkzEACKFUnpp+wIVHpckMfBqN8BE5dUbWJc GyQ7wXWajLtlPdw1nNw0Wrv+ob2RCT7qQlUo6GRLcvj9Fn5tR4hBvR6D3m8aR0AGHbcC62cq I7LjaSDP5j/em4oVL2SMgNTrXgE2w33JMGjAx9oBzkxmKUqprhJomPwmfDHMJ0t7y39Da724 oLPTkQDpJL1kuraM9TC5NyLe1+MyIxqM/8NujoJbWeQUgGjn9uxQAil7o/xSCjrWCP3kZDID vd5ZaHpdl8e1mTExQoKr4EWgaMjmD/a3hZ/j3KfTVNpM2cLfD/QwTMaC2fkK8ExMsz+rUl1H icmcmpptCwOSgwSpPY1Zfio6HvEJp7gmDwMgozMfwQuT9oxyFTxn1X3rn1IoYQF3P8gsziY5 qtTxy2RrgqQFm/hr8gM78RhP54UPltIE96VywviFzDZehMvuwzW//fxysIoK97Y/KBZZOQs+ /T+Bw80Pwk/dqQ8UmIt2ffHEgwCTbkSm711BejapWCfklxkMZDp16mkxSt2qZovboVjXnfuq wQ1QL4o4t1hviM7LyoflsCLnQFJh6RSBhBpKQinMJl/z0A6NYDkQi6vEGMDBWX/M2vk9Jvwa v0cEBfY3Z5oFgkh7BUORsu1V+Hn0fR/Lqq/Pyq+nTR26WzGDkolLsDr3IH0TiAVH5ZuPxyz6 abzjfg== Message-ID: <312a138c-e5b2-4bfb-b50b-40c82c55773f@schaufler-ca.com> Date: Wed, 29 May 2019 08:53:34 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <14347.1559127657@warthog.procyon.org.uk> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="cNkJJFaLGPzGj0MrH4stT0km9ovmzGP9Z" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --cNkJJFaLGPzGj0MrH4stT0km9ovmzGP9Z Content-Type: multipart/mixed; boundary="CGJ0IeN7E9pxspTs8jkc4kNwow51RM68Y"; protected-headers="v1" From: Casey Schaufler To: David Howells , Jann Horn Cc: Al Viro , raven@themaw.net, linux-fsdevel , Linux API , linux-block@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module , kernel list Message-ID: <312a138c-e5b2-4bfb-b50b-40c82c55773f@schaufler-ca.com> Subject: Re: [PATCH 3/7] vfs: Add a mount-notification facility References: <155905930702.7587.7100265859075976147.stgit@warthog.procyon.org.uk> <155905933492.7587.6968545866041839538.stgit@warthog.procyon.org.uk> <14347.1559127657@warthog.procyon.org.uk> In-Reply-To: <14347.1559127657@warthog.procyon.org.uk> --CGJ0IeN7E9pxspTs8jkc4kNwow51RM68Y Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US On 5/29/2019 4:00 AM, David Howells wrote: > Jann Horn wrote: > >>> +void post_mount_notification(struct mount *changed, >>> + struct mount_notification *notify) >>> +{ >>> + const struct cred *cred =3D current_cred(); >> This current_cred() looks bogus to me. Can't mount topology changes >> come from all sorts of places? For example, umount_mnt() from >> umount_tree() from dissolve_on_fput() from __fput(), which could >> happen pretty much anywhere depending on where the last reference gets= >> dropped? > IIRC, that's what Casey argued is the right thing to do from a security= PoV. > Casey? You need to identify the credential of the subject that triggered the event. If it isn't current_cred(), the cred needs to be passed in to post_mount_notification(), or derived by some other means. > Maybe I should pass in NULL creds in the case that an event is being ge= nerated > because an object is being destroyed due to the last usage[*] being rem= oved. You should pass the cred of the process that removed the last usage. If the last usage was removed by something like the power being turned off on a disk drive a system cred should be used. Someone or something caused the event. It can be important who it was. > [*] Usage, not ref - Superblocks are a bit weird in their accounting. > > David --CGJ0IeN7E9pxspTs8jkc4kNwow51RM68Y-- --cNkJJFaLGPzGj0MrH4stT0km9ovmzGP9Z Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEC+9tH1YyUwIQzUIeOKUVfIxDyBEFAlzuqwkACgkQOKUVfIxD yBEWag//SJA6JpQHXqyOeXOtCod82vVguKxz7q2fheSMMS+T8bB0rX2XTO4rho9D t5wUt9c1+HtGk8HBvbS7vOnjhXso6RshvI2uUEfE0MOQ/Y1FBIqXwrTzpSs8/FVE tv3YFqCWlcaLOfnh/Gl0GvK+o5DGMVFDVsv0j3ke5VihJ4enHnn18AncowE5nVu3 n9GahTQcWaRIgYIHJ9Wr0olwAQsa2TQpj/0wJR3I5ni1hY10wknm9jCIw2L612xU l5rZ73EqvgIjqsq9m1rgZqjH3QypYvTgdDCd9I/AdZmAI8QJ3JISRzZlKGw2o6GL ZIExEzQCVMzGyqEDkTxQQlXjczfF7jHCWQ9+iyyz747JMRrx1Kr6LqZlTJsfQCc0 F+Ytx0D8RVkwkpkrzIQz5eS/R2ib2lYH7Jtk9RhreDagrzkieeyZ3A3Y0feYqIb3 O7tGYBfQVWx5dVjB5nZ7v/aUw7Wc929yiONfiHLxSg8U4xlj0mFSa0HFOYC4DzaG C0NSVb7xvoDfpyt6m9Wv1mF7cJKkLFffeMfqUREZAcNEdiYrg90Ho6cJ5tZVreSu rVgR81R7SSVANygbfauj9X3N3D4fsWxu+D81zz0B9CBgy8GP+p/kWrL45hRC4CLN hG3yC60hUm54xq2H3YT775eyGBcDixyPsh5qmTXQ21MtLLm3W1c= =qEff -----END PGP SIGNATURE----- --cNkJJFaLGPzGj0MrH4stT0km9ovmzGP9Z--