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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4EFF9C44512 for ; Thu, 16 Jul 2026 14:59:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3C7CE6B0114; Thu, 16 Jul 2026 10:59:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 379826B0116; Thu, 16 Jul 2026 10:59:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 268556B0117; Thu, 16 Jul 2026 10:59:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id EF7C36B0114 for ; Thu, 16 Jul 2026 10:59:34 -0400 (EDT) Received: from smtpin12.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id DD777C019E for ; Thu, 16 Jul 2026 13:43:40 +0000 (UTC) X-FDA: 84994757400.12.DFA9368 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf01.hostedemail.com (Postfix) with ESMTP id 243C340008 for ; Thu, 16 Jul 2026 13:43:38 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="ddRFPeB/"; spf=pass (imf01.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784209419; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc: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=oWUsUTsHTYC4oF1+U1zCOlOpJa+o/HcjMqULEm1jNKI=; b=dDa4PWs4PRF43IlBIBcWk7DelwZTIl7MEx9ymLbA94I5yDQGhnzsp1DnHQo39Fqh9r7Edr Qw+oFWdfGs4Mr52IUqt+gvDTdrs/Q516X9AZEEkw6uScCZ/4ZpmkqMT44Jij23r3dBfwTH r5M7xUEpXdOdRJzXRq+hQSgxgq+Koxw= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784209419; b=dBlkWK+WDVYvOBpbaVO0mcWFlN7CYWcQHJQHpG2FXQTZsKjWNEHv2nOdwAK12R459+SW8J GrkXi2L794LqH5r2VDNahu/Y9203AZRoMiOkwyVf0AtLo5W1W0SKjqRyEVi+giQKRS6tcN oFWHpSsKOn01+AEaqyVEfBRYTHwhbS8= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="ddRFPeB/"; spf=pass (imf01.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 8F77C601ED; Thu, 16 Jul 2026 13:43:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D11B41F00A3A; Thu, 16 Jul 2026 13:43:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784209418; bh=oWUsUTsHTYC4oF1+U1zCOlOpJa+o/HcjMqULEm1jNKI=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=ddRFPeB/dy4N9t+1VV61tUOy6RSwcG9ODLZw+J8v/DsHFuvLSCm+SEyltiVJaOJNq zfJEikRpZms7kR5FsxnW/wY68XiDM/HWCi7PgE+3mtkbuQC7zlsu+x9UM1MxQo71pB L7i5hBbUGDOVT7oE57f976DdElPde+afbcy8vQ5PFOO+I32bG9ryUvKL4s1FGTIiKn tI2Phf7XpCYEruV/Pcz11uYKUlbxmiCmMo9YcJdQwQ8bbrjgLRkkB+5hVvrV9f0xot zjF/I+b9w6nqb3R9uLXQHPiwG9dOe6iwPzAHQxhwLMWUlVAwdKTyXNhRj3DgrjEkUU VW1D68HV5+d+g== From: "Lorenzo Stoakes (ARM)" Date: Thu, 16 Jul 2026 14:43:11 +0100 Subject: [PATCH 3/3] mm/mseal: remove further superfluous comments, do_mseal() MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260716-mseal-fixups-v1-3-3a9609bf041b@kernel.org> References: <20260716-mseal-fixups-v1-0-3a9609bf041b@kernel.org> In-Reply-To: <20260716-mseal-fixups-v1-0-3a9609bf041b@kernel.org> To: Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Alexander Viro , Christian Brauner , Jan Kara , Kees Cook , David Hildenbrand , Mike Rapoport , Suren Baghdasaryan , Michal Hocko Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Lorenzo Stoakes (ARM)" X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=4242; i=ljs@kernel.org; h=from:subject:message-id; bh=3XEOElWo0Iax9roa0jK1sDNI5MbeHwqjApf5pqY6yz0=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLIi7n+adExAyarM7UFw98yGhv+zX/n8V1ryQedU13Xv7 fJWT64WdZSyMIhxMciKKbI8/yK+P0gkbF7nBX83mDmsTCBDGLg4BWAiU8UYGTZdV2ExVnl8xdrM TzDynwdjRGP87vUdSg/3zqvgrD3C7cXwP/rh4aR5i1REq12Cd/AFBBhurriRJ3MixZtjhbT/4XU JnAA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 243C340008 X-Stat-Signature: dttudihczby3msotcefg5hd3719ywyge X-HE-Tag: 1784209418-892948 X-HE-Meta: U2FsdGVkX18vBz6O+LC9OcuwGfNZ0aJPnmGfSaiTbgxJCA55xCCGkyqyxfioNyNVpvTKIdhtfLv8I8aFEMO1GsTS0CBRyNXDfsgvqVs+6WiKy1IihgwVhaQjdmWD9GK5V4AVEY56SfiAKD6GJCusy3UTRW7ZyFZ9OKTc/ZMRNwVhiPIs3aa3uSBmwweFif9XUlvPlYb44crQVzmxIdjrxKIx5y9BRmB7KhDsXW2lqIJsRd58TNiXJ0f922rbyfMa6fgjCnUgJNirBMZSKyuTAHiwyOE8Ud+UmTbc3491bRgK35qDxGNxgxAHZ3HSRcBaaAuTsqULb07hUWQIv8Qcg1e9ONmjiBUXxXMIGPIDhxzkxQdOv0geblmyl46t0Gm/XFAXuw+Hf7NcOAHy2KCRZhN4fXc1OGm6SK3dklME+rbilnINSU/hLrAvBI58XTxcOt9nH2XTeHmXNNCzUIUWJAjpM/99ld+Q6jpFy/4/BHCUilTiJfCyaVttQGeH9ujbz/93BN1AN1GY+vVD2vD9iB63yggojq5VwlUqf6NjbVOkWJ3c+wG0u5cBA7aJ5mu05BGochn9CVETid5iBJ+Sz1lS29T//HmZIqbXv3BdsF95cQoZRH3FhhKZT5EpDyQ0qrUWLssLO7rX6D3wv44NlEhA1e6Y0NvjxionB2RKCeV4gOegcAscadL21U9iRYIkRsRVS1iR2o6BjQu+Vdi+k/HVQRCNRyv3nUKLs4neadlQYmbbaz2w6V2gLB7kf7FzZd2PqAiig49I2E0VJpSGL64eblpigRBCn1r/cY2H0f2s5LAby3Ipe0ScsbgukzDilQ4F637faASI5YUyoIMnwjxb/uGbrTBsVPhyKtPiwI3/VgjYZQE3xaxmCzS5dawF4AH/hNjAlYEaGsgF52we5uG9nXlz5ZBmVehUFQkr59/7P4rvtQUuTQJmmy0TzFYNUPmPMp2TEekgzuTwm3Q vdltt8BI fp3Mmd3iHBck4JEmLu4u2HqS7XK5LgV8GSOjdZjRpAOkpIPbE32Raj8JHAZTZWlRd8mo8MBneLmggcc3ax8jrGoFjvuewUGcp7u2mW4AZkOsxWsok8kJdIVZ1ca/6ddmMnPxXV//lsJmoXbniREoVxtvchdkSK7z2hma9jJJKgCioqXMoGHX3FlWUvSUtj11SSOxSwfDNubCcyBJKQI70PP+A2Mtnr/8o89j7GelV3T1Gyt/UtXIem3GeP7xNO7A6o19mNKP0bJdyU/8y+6sF7LfO4qb75BoeDEHK Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: There's no need to abstract do_mseal() any longer so put the system call implementation in the system call declaration. The comment around do_mseal() is strangely formatted, overly long and adds a lot of superfluous information that the code already provides, so boil it down to the essentials. Signed-off-by: Lorenzo Stoakes (ARM) --- mm/mseal.c | 74 ++++++++++++++------------------------------------------------ 1 file changed, 16 insertions(+), 58 deletions(-) diff --git a/mm/mseal.c b/mm/mseal.c index 5930551d84f2..d01ab35d3f0f 100644 --- a/mm/mseal.c +++ b/mm/mseal.c @@ -99,60 +99,24 @@ void mseal_mmap_page_zero(void) } /* - * mseal(2) seals the VM's meta data from - * selected syscalls. + * Seal VMAs in the specified input range to prevent an attacker replacing what + * is mapped in the range with something else. * - * addr/len: VM address range. + * Disallows: + * - VMA unmapping, remapping or shrinking. + * - Overwriting the VMA with another one via mmap(), mremap() or similar. + * - Alteration of properties via mprotect()/pkey_mprotect(). + * - Destructive madvise() behaviours (like MADV_DONTNEED) on anonymous read-only + * ranges. * - * The address range by addr/len must meet: - * start (addr) must be in a valid VMA. - * end (addr + len) must be in a valid VMA. - * no gap (unallocated memory) between start and end. - * start (addr) must be page aligned. + * Since unmapped ranges can be mapped at any time, the input range must span + * mapped ranges only. * - * len: len will be page aligned implicitly. - * - * Below VMA operations are blocked after sealing. - * 1> Unmapping, moving to another location, and shrinking - * the size, via munmap() and mremap(), can leave an empty - * space, therefore can be replaced with a VMA with a new - * set of attributes. - * 2> Moving or expanding a different vma into the current location, - * via mremap(). - * 3> Modifying a VMA via mmap(MAP_FIXED). - * 4> Size expansion, via mremap(), does not appear to pose any - * specific risks to sealed VMAs. It is included anyway because - * the use case is unclear. In any case, users can rely on - * merging to expand a sealed VMA. - * 5> mprotect and pkey_mprotect. - * 6> Some destructive madvice() behavior (e.g. MADV_DONTNEED) - * for anonymous memory, when users don't have write permission to the - * memory. Those behaviors can alter region contents by discarding pages, - * effectively a memset(0) for anonymous memory. - * - * flags: reserved. - * - * return values: - * zero: success. - * -EINVAL: - * invalid input flags. - * start address is not page aligned. - * Address range (start + len) overflow. - * -ENOMEM: - * addr is not a valid address (not allocated). - * end (start + len) is not a valid address. - * a gap (unallocated memory) between start and end. - * -EPERM: - * - In 32 bit architecture, sealing is not supported. - * Note: - * user can call mseal(2) multiple times, adding a seal on an - * already sealed memory is a no-action (no error). - * - * unseal() is not supported. + * The flags parameter is currently reserved. */ -static int do_mseal(unsigned long start, size_t len_in, unsigned long flags) +SYSCALL_DEFINE3(mseal, unsigned long, start, size_t, len, unsigned long, flags) { - size_t len; + size_t len_aligned; unsigned long end; /* Verify flags not set. */ @@ -163,12 +127,12 @@ static int do_mseal(unsigned long start, size_t len_in, unsigned long flags) if (!PAGE_ALIGNED(start)) return -EINVAL; - len = PAGE_ALIGN(len_in); + len_aligned = PAGE_ALIGN(len); /* Check to see whether len was rounded up from small -ve to zero. */ - if (len_in && !len) + if (len && !len_aligned) return -EINVAL; - end = start + len; + end = start + len_aligned; if (end < start) return -EINVAL; @@ -177,9 +141,3 @@ static int do_mseal(unsigned long start, size_t len_in, unsigned long flags) return mseal(start, end); } - -SYSCALL_DEFINE3(mseal, unsigned long, start, size_t, len, unsigned long, - flags) -{ - return do_mseal(start, len, flags); -} -- 2.55.0