From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lamorak.hansenpartnership.com (lamorak.hansenpartnership.com [198.37.111.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0817A2040B6; Sun, 14 Dec 2025 22:18:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.37.111.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765750731; cv=none; b=Tl977lcTvuGTnoaqfN8oHTQBodEK5tDMvFOJe5zgHBagfyVyzr6BS0pWHyqOS4AYZcio2bjTxaHz6ChesE8PoV6QWS0G+rSnuaRf4XTNYMbtV9ERHCFrMLl31Adkl3mdLtbEsumaJjQsU0vq7KnfbKvKk17X3cJQgrDZLGL12cs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765750731; c=relaxed/simple; bh=9bqt5vhV3V0sLffhhCOQZh7auNGkn0Uq0cEn122q6y4=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=ij3pGJh1vHidjHcn3rTinufPEyJfEOQN7TMmkfm/hy2YD0x9YM5416tpjNlBHtD1PqkVU6nLT0S2NBHbQTDuFCXydeB81ETZxbYBG+cIsB74kqnNlWQKQHRGGi71LRNSzOLXpyhUXN8yBimz3CLrMy1RN3WpJRGnScKjAeImZKU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com; spf=pass smtp.mailfrom=HansenPartnership.com; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=kc30vtuu; arc=none smtp.client-ip=198.37.111.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="kc30vtuu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1765750726; bh=9bqt5vhV3V0sLffhhCOQZh7auNGkn0Uq0cEn122q6y4=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=kc30vtuuEcmki+nfD5kutaEYLZSYym38TkUsffn8E80uGD0OiEo+FQVTLDWmdc9pa 170TIzdQUUsVz3FRW4/NrjsE0V4hkG7Z4EWsQsobW6IbajOc+x6rmzCpZZl7pR+0Lq PMW+EVvK1uZ0FEx10BPoIMy8n/KFlMPF7pewm3WA= Received: from [172.20.4.117] (122x212x32x58.ap122.ftth.ucom.ne.jp [122.212.32.58]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lamorak.hansenpartnership.com (Postfix) with ESMTPSA id C88D51C0202; Sun, 14 Dec 2025 17:18:44 -0500 (EST) Message-ID: <64e3e4e0a92848fd3b02a213c754f096d2026463.camel@HansenPartnership.com> Subject: Re: [PATCH] KEYS: trusted: Use get_random-fallback for TPM From: James Bottomley To: Jarkko Sakkinen , linux-integrity@vger.kernel.org Cc: David Howells , Paul Moore , James Morris , "Serge E. Hallyn" , Mimi Zohar , "open list:KEYS/KEYRINGS" , "open list:SECURITY SUBSYSTEM" , open list Date: Mon, 15 Dec 2025 07:18:41 +0900 In-Reply-To: <20251214213236.339586-1-jarkko@kernel.org> References: <20251214213236.339586-1-jarkko@kernel.org> Autocrypt: addr=James.Bottomley@HansenPartnership.com; prefer-encrypt=mutual; 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MAdnPcDVFzaXJdlAAJdjfg/lyJtAyxifflG8NnXJ3elwGqoBso84XBNWWzbc5VKmatzhYLOvXtfzDhu4mNPv/z7S1HTtRguI0NlH5RVBzSvfzybin9hysE3/+r3C0HJ2xiOHzucNAmG03aztzZYDMTbKQW4bQqeD5MJxT68vBYu8MtzfIe41lSLpb/qlwq1qg0iQElBBgBAgAPBQJUdhaZAhsMBQkA7U4AAAoJEIFK5HwhSFTW3YgH/AyJL2rlCvGrkLcas94ND9Pmn0cUlVrPl7wVGcIV+6I4nrw6u49TyqNMmsYam2YpjervJGgbvIbMzoHFCREi6R9XyUsw5w7GCRoWegw2blZYi5A52xe500+/RruG//MKfOtVUotu3N+u7FcXaYAg9gbYeGNZCV70vI+cnFgq0AEJRdjidzfCWVKPjafTo7jHeFxX7Q22kUfWOkMzzhoDbFg0jPhVYNiEXpNyXCwirzvKA7bvFwZPlRkbfihaiXDE7QKIUtQ10i5kw4C9rqDKwx8F0PaWDRF9gGaKd7/IJGHJaac/OcSJ36zxgkNgLsVX5GUroJ2GaZcR7W9Vppj5H+C4UgRkuRyTEwgqhkjOPQMBBwIDBOySomnsW2SkApXv1zUBaD38dFEj0LQeDEMdSE7bm1fnrdjAYt0f/CtbUUiDaPodQk2qeHzOP6wA/2K6rrjwNIWJAT0EGAEIACcDGyAEFiEE1WBuc8i0YnG+rZrfgUrkfCFIVNYFAmWoM/gFCQSxfmUACgkQgUrkfCFIVNZhTgf/VQxtQ5rgu2aoXh2KOH6naGzPKDkYDJ/K7XCJAq3nJYEpYN8G+F8mL/ql0hrihAsHfjmoDOlt+INa3AcG3v0jDZIMEzmcjAlu7g5NcXS3kntcMHgw3dCgE9eYDaKGipUCubdXvBaZWU6AUlTldaB8FE6u7It7+UO+IW4/L+KpLYKs8V5POInu2rqahlm7vgxY5iv4Txz4EvCW2e4dAlG 8mT2Eh9SkH+YVOmaKsajgZgrBxA7fWmGoxXswEVxJIFj3vW7yNc0C5HaUdYa5iGOMs4kg2ht4s7yy7NRQuh7BifWjo6BQ6k4S1H+6axZucxhSV1L6zN9d+lr3Xo/vy1unzA== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Sun, 2025-12-14 at 23:32 +0200, Jarkko Sakkinen wrote: > 1. tpm2_get_random() is costly when TCG_TPM2_HMAC is enabled and thus > its > =C2=A0=C2=A0 use should be pooled rather than directly used. This both re= duces > =C2=A0=C2=A0 latency and improves its predictability. >=20 > 2. Linux is better off overall if every subsystem uses the same > source for > =C2=A0=C2=A0 the random bistream as the de-facto choice, unless *force ma= jeure* > =C2=A0=C2=A0 reasons point to some other direction. >=20 > In the case, of TPM there is no reason for trusted keys to invoke TPM > directly. That assertion isn't correct: you seem to have forgotten we had this argument six or seven years ago, but even that was a reprise of an even earlier one. Lore doesn't go back far enough for the intermediate one on the tpm list, but the original was cc'd to lkml: https://lore.kernel.org/all/1378920168.26698.64.camel@localhost/ The decision then was to use the same random source as the key protection. Unfortunately most of the active participants have moved on from IBM and I don't have their current email addresses, but the bottom line is there were good reasons to do trusted keys this way that your assertions above don't overcome. I'm not saying we shouldn't reconsider the situation, but we need a reasoned debate rather than simply doing it by fiat. Regards, James =20