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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 468F6C021A4 for ; Mon, 24 Feb 2025 19:07:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D203D28000D; Mon, 24 Feb 2025 14:07:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id CCEF628000A; Mon, 24 Feb 2025 14:07:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B48F628000D; Mon, 24 Feb 2025 14:07:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 940CA28000A for ; Mon, 24 Feb 2025 14:07:31 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 53A98121B77 for ; Mon, 24 Feb 2025 19:07:31 +0000 (UTC) X-FDA: 83155771902.12.944C2F5 Received: from mail-ot1-f46.google.com (mail-ot1-f46.google.com [209.85.210.46]) by imf18.hostedemail.com (Postfix) with ESMTP id 6E4591C001B for ; Mon, 24 Feb 2025 19:07:29 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=mC1JG6xl; spf=pass (imf18.hostedemail.com: domain of jeffxu@chromium.org designates 209.85.210.46 as permitted sender) smtp.mailfrom=jeffxu@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1740424049; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=wQCHGb/1mEcTjB0ohJkHDUAZUcOj91T5VUbYgnfzfKs=; b=zr41MA75r6KJeHEKC8Okl7Jum2dXRnAfDxpWqXo2zLIgDHHHa7neYUGb8lLxncGt90Bc5c K5CUPNcS/cJ8+34JZUOFLJf3xa701fJymgeaQAwQboznI03gnk/EPclUbuTfeLD0d5rWq5 OnGUVPTW35Xwatg1iX+ToWlZIKNIqWs= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=mC1JG6xl; spf=pass (imf18.hostedemail.com: domain of jeffxu@chromium.org designates 209.85.210.46 as permitted sender) smtp.mailfrom=jeffxu@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1740424049; a=rsa-sha256; cv=none; b=6XCUwoB5iVdceh4B+5LaN53DoKVEkiwH7cneZlk3rL3WX9306CcTBZmkk4QCXg6pCJJh5x zdaspWIREkgSkS6uqG3FBmpt1Gq1t1aWdsWgs96FRux3+2+6Vsd2/qZIod6GeUEVxwmPiQ LdD5mW2EOhuvSp/9DiDBpYkgo1LqYMQ= Received: by mail-ot1-f46.google.com with SMTP id 46e09a7af769-7272c81328bso367243a34.1 for ; Mon, 24 Feb 2025 11:07:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1740424048; x=1741028848; darn=kvack.org; h=content-transfer-encoding:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=wQCHGb/1mEcTjB0ohJkHDUAZUcOj91T5VUbYgnfzfKs=; b=mC1JG6xlxAk5DS3OJymieA8qPAoi4G74GKfqACLc+pAgkHW+AijOZ3YpL5BiCPIOxo XrkfFEOUWehZ2zDnLv4vItVDxZlzV9S146A59q5Zn8AtqjjfPSUGhVHXdxD8znsSLO2M PSxOYoxJoBYWI/WP+XqdOnozrwFEFL0tTvgJc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740424048; x=1741028848; h=content-transfer-encoding:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=wQCHGb/1mEcTjB0ohJkHDUAZUcOj91T5VUbYgnfzfKs=; b=nLLXrFfSYY8fvIulxDtj+GvEWcU2xNsXqms2xtWO90a5nGC99ar/eAcL/8tKGaZoXM IbPaNiiy7QrStzc72U2Kn0mMJ4kPEB4JbjgNvJjrQXcXbbU/DGYuibZIGgLH4QKZF4Zg Jto/TGokkkGv220wx8xGZScKqhCQmvNmcEAuk1AwKFP9nXGaCC+LBi9dstFX/ECzdr/J IDWOUcJ3b9C1cEo9ka3BCqoS/SzeaUbltO2mLVBw9JwVtJLkgCBkNwimhxyDBa+qi+L/ lCA6qFG4no+FqoyQ48GopQcm6PSMohHh604i/+Vi0OXqDbKrb2r3PsiZjUnDQbemfZnp m+gQ== X-Forwarded-Encrypted: i=1; AJvYcCUh1jUN/r2pSWK9EWJHdJ2W4aZb5E44g0IlGaknSe7YoBqrnj+7sdSv3Xoe3EjIN3oDDC3M3cJB+w==@kvack.org X-Gm-Message-State: AOJu0YwqxDgx4oQNNB3eAc8Nn8RCymP7CbVCSus/zPmPIzE5zKZN3Z5G c6bEI642ft0VxmGq9DOg6cG32Sf2hEwdIw+6HN3kZuvc5rRStfCIoQnl7kyGphbQENBeQl0DdJ6 6ilKPAFBWPmHXPWVaioFkr0jXbWFft9XT0DZL X-Gm-Gg: ASbGnctVMeTXO4f0qRo12/NxZzZJ+FIMa/ad0h89B89BdO5P+KnlvSUrfMJoUDvSlD/ 9PaGZQ5zPKXgBqAVLBqSiMQGnLTp5xUUO3hHHf5m5j6f+9aFGR5qVT/0/USqqpFwEyc9TU9Bl38 HVWirupTJIxIC0tpDFMr6qxrI5A8DijcA2M6G7 X-Google-Smtp-Source: AGHT+IFrbrwEmuYOunYtHNdMni7okQkt3QFjQtD8vHn5l5zTdcXfnyAMvDD/7Ae+veDhcxsJz6JhhrxQ5jvSrdRN1DM= X-Received: by 2002:a05:6808:201f:b0:3f4:11a1:615a with SMTP id 5614622812f47-3f4247a9cd8mr4184198b6e.6.1740424048367; Mon, 24 Feb 2025 11:07:28 -0800 (PST) MIME-Version: 1.0 References: <20250224174513.3600914-1-jeffxu@google.com> <20250224174513.3600914-2-jeffxu@google.com> <443992d7-f694-4e46-b120-545350a5d598@intel.com> <3nxcy7zshqxmjia7y6cyajeoclcxizkrhhsitji5ujbafbvhlu@7hqs6uodor56> In-Reply-To: <3nxcy7zshqxmjia7y6cyajeoclcxizkrhhsitji5ujbafbvhlu@7hqs6uodor56> From: Jeff Xu Date: Mon, 24 Feb 2025 11:07:17 -0800 X-Gm-Features: AWEUYZnFbU7bWMO5mDGdFqrYIJo2aJVDJw1Nuop8sup_tSwiXkOaJwtHACFOP_4 Message-ID: Subject: Re: [PATCH v6 1/7] mseal, system mappings: kernel config and header change To: "Liam R. Howlett" , Jeff Xu , Dave Hansen , akpm@linux-foundation.org, keescook@chromium.org, jannh@google.com, torvalds@linux-foundation.org, vbabka@suse.cz, lorenzo.stoakes@oracle.com, adhemerval.zanella@linaro.org, oleg@redhat.com, avagin@gmail.com, benjamin@sipsolutions.net, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-mm@kvack.org, jorgelo@chromium.org, sroettger@google.com, hch@lst.de, ojeda@kernel.org, thomas.weissschuh@linutronix.de, adobriyan@gmail.com, johannes@sipsolutions.net, pedro.falcato@gmail.com, hca@linux.ibm.com, willy@infradead.org, anna-maria@linutronix.de, mark.rutland@arm.com, linus.walleij@linaro.org, Jason@zx2c4.com, deller@gmx.de, rdunlap@infradead.org, davem@davemloft.net, peterx@redhat.com, f.fainelli@gmail.com, gerg@kernel.org, dave.hansen@linux.intel.com, mingo@kernel.org, ardb@kernel.org, mhocko@suse.com, 42.hyeyoo@gmail.com, peterz@infradead.org, ardb@google.com, enh@google.com, rientjes@google.com, groeck@chromium.org, mpe@ellerman.id.au, aleksandr.mikhalitsyn@canonical.com, mike.rapoport@gmail.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 6E4591C001B X-Stat-Signature: b3c6iy44kgm4yjaewzyq95uupfipt358 X-Rspam-User: X-HE-Tag: 1740424049-290166 X-HE-Meta: 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 bL2ciVjr vyWmJAmeCymv8popZgbCSVNiVWhLzuYPOo3K9wdXcSQac/MhO5VDmLzzTOuhc0yl0F3JI6fsB0msx6MZWZ/VjBIEGMjBgNzWb1zBpV/Ea7Tf2HuhcR0iNqVILJCNJQf2V4luILXoXOwhWpT1CTRLZBM2mW4h9o1o0ITiNIgV1VS9FKV05FDQ1o3bWfKV+WWngt8GJun2hqXAuqq0HHRRh96GjXQ3/j8rmWHf4SzbTj8HXztRbkaBRauVllVXDa3gLF1NmmX3qs86cB+Nnnh8MrixicGQ5H8ruJvni0hjVDHvs/k4N5BZBA2pr3AgcU+QNc5S5Ic/fyDN+m/aoeYFM0jZaQw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Feb 24, 2025 at 11:03=E2=80=AFAM Liam R. Howlett wrote: > > * Jeff Xu [250224 13:44]: > > On Mon, Feb 24, 2025 at 10:21=E2=80=AFAM Dave Hansen wrote: > > > > > > On 2/24/25 09:45, jeffxu@chromium.org wrote: > > > > +/* > > > > + * mseal of userspace process's system mappings. > > > > + */ > > > > +#ifdef CONFIG_MSEAL_SYSTEM_MAPPINGS > > > > +#define MSEAL_SYSTEM_MAPPINGS_VM_FLAG VM_SEALED > > > > +#else > > > > +#define MSEAL_SYSTEM_MAPPINGS_VM_FLAG VM_NONE > > > > +#endif > > > > > > This ends up looking pretty wonky in practice: > > > > > > > + vm_flags =3D VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|VM_PFNMAP; > > > > + vm_flags |=3D MSEAL_SYSTEM_MAPPINGS_VM_FLAG; > > > > > > because MSEAL_SYSTEM_MAPPINGS_VM_FLAG is so much different from the > > > other ones. > > > > > > Would it really hurt to have > > > > > > #ifdef CONFIG_64BIT > > > /* VM is sealed, in vm_flags */ > > > #define VM_SEALED _BITUL(63) > > > +#else > > > +#define VM_SEALED VM_NONE > > > #endif > > > > > > ? > > > > > VM_SEALED isn't defined in 32-bit systems, and mseal.c isn't part of > > the build. This is intentional. Any 32-bit code trying to use the > > sealing function or the VM_SEALED flag will immediately fail > > compilation. This makes it easier to identify incorrect usage. > > > > The reason that two #defines are needed is because you can have mseal > enabled while not sealing system mappings, so for this to be clean we > need two defines. > > However MSEAL_SYSTEM_MAPPINGS_VM_FLAG, is _way_ too long, in my opinion. > Keeping with "VM_SEALED" I'd suggest "VM_SYSTEM_SEALED". > > > For example: > > Consider the case below in src/third_party/kernel/v6.6/fs/proc/task_mmu= .c, > > third_party? > Sorry, I pasted the code path from ChromeOS code base, it is actually in the kernel itself. fs/proc/task_mmu.c > > > > #ifdef CONFIG_64BIT > > [ilog2(VM_SEALED)] =3D "sl", > > #endif > > > > Redefining VM_SEALED to VM_NONE for 32 bit won't detect the problem > > in case that "#ifdef CONFIG_64BIT" line is missing. > > I don't think it is reasonable to insist on doing things differently in > the kernel because you have external tests that would need updating. > These things can change independently, so I don't think this is a valid > argument. > > If these are upstream tests, and we need these tests to work then they > can be fixed. > As above, this is actually kernel code, not test. -Jeff > > > > Please note, this has been like this since the first version of > > mseal() RFC patch, and I prefer to keep it this way. > > Thanks, > Liam