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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7ABE7C64EC4 for ; Fri, 10 Mar 2023 17:16:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230426AbjCJRQv (ORCPT ); Fri, 10 Mar 2023 12:16:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230369AbjCJRQp (ORCPT ); Fri, 10 Mar 2023 12:16:45 -0500 Received: from mail-wm1-x329.google.com (mail-wm1-x329.google.com [IPv6:2a00:1450:4864:20::329]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA782F28A8 for ; Fri, 10 Mar 2023 09:16:21 -0800 (PST) Received: by mail-wm1-x329.google.com with SMTP id bg16-20020a05600c3c9000b003eb34e21bdfso6600636wmb.0 for ; Fri, 10 Mar 2023 09:16:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1678468579; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :from:to:cc:subject:date:message-id:reply-to; bh=hAR+tMsmaLBFht+LOOo6dlI0N6MA2He87h1FBYd556U=; b=GgkXGPRYJD1/1urxX2uFNloozieprwnGBXW20LtiPUWOPXlneOPVOP8cgbBUJjU+HW OJA+rvAJJTc3m53enR+tP+rPGkhxOITNNeKC8+rL74m+7HwUwKHgkHS5CklSp5/e4l8b xc7OjOmOZGUlLWpofLetfpEQbBhjJ0RcVCbNwVKhZMnuvrQ9nGq6FxARxOb5543igWwm Um7sGDsQveroqRyU7Rcj1w/75Oz6hywGtoXX0S4x1RTkcY6z4XVtv7jxxeF2bqI71AyV 9IZrjfQy4u4OGNNpNqASHy/GjP04vsWF6K4vBEnADj6JgtdNlytnunoQLnMsLBBULlAo Hwsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678468579; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=hAR+tMsmaLBFht+LOOo6dlI0N6MA2He87h1FBYd556U=; b=cgLbTxaDh6wisfBXWxd1nHerA4isQa9Jj9PB81y8NsYfHRM+fJb2/VCOKbN5ttKo9G PnU7sL1R9ui3nF0m2h5j2PzjhUgi56G7efiHkPaUmrO3zB164/PJSfzJ0MOQyKwtyRi+ 5hxo+HxwQwClQjh4M8Cp1eIJmbwDMqaDBfgjV1s86ndEB96uORcmlAQ/UpoPdJZ5fEIH daL0iWFKscj7hmmYexmth6l6MTqK/6mvGkbTkq3o45RB5cYiWvDFxc8AjNlcZ0cIJ7uX Ik4HD7GF0EmzgnIhrSkeCMPiGxitKterC4+BuPNIwdxnLShHDk/Rl3ajTh0iviyECrZz GPSQ== X-Gm-Message-State: AO0yUKXG7sZgWzcMrXzHfvKfaZ537rIsMN/CMSmhcOjSKOgvh2F/K7jB 8+pT+oNCCCae5lzIRg7R0yGD/3+gozYAtA== X-Google-Smtp-Source: AK7set/lS3wOFh5G2z0zqZSDgneiAy5uHUpEj6yjIO9vtmogf89N2COYP70UlHfslHyih10vrE94eg== X-Received: by 2002:a05:600c:35c1:b0:3df:deb5:6ff5 with SMTP id r1-20020a05600c35c100b003dfdeb56ff5mr3633557wmq.24.1678468579241; Fri, 10 Mar 2023 09:16:19 -0800 (PST) Received: from archlinux (p200300e7370bbe5f73e3aef84e627e25.dip0.t-ipconnect.de. [2003:e7:370b:be5f:73e3:aef8:4e62:7e25]) by smtp.gmail.com with ESMTPSA id i1-20020a05600c290100b003e89e3284fasm414421wmd.36.2023.03.10.09.16.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Mar 2023 09:16:18 -0800 (PST) Date: Fri, 10 Mar 2023 18:16:17 +0100 From: Nils Hartmann To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] Using MAP_SHARE_VALIDATE in mmap without fd Message-ID: <20230310171617.wqnqs42l2viwjsz5@archlinux> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey, I have a rather simple question about the MAP_SHARED_VALIDATE flag in mmap. When used without a file pointer, EINVAL is returned. Is there a reason for this? I researched a bit but could not find anything. I attached a simple patch that adds MAP_SHARE_VALIDATE to the flags switch and checks for invalid flags. Signed-off-by: Nils Hartmann --- mm/mmap.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 740b54be3..fd7db51af 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1196,6 +1196,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr, { struct mm_struct *mm = current->mm; vm_flags_t vm_flags; + unsigned long flags_mask; int pkey = 0; validate_mm(mm); @@ -1266,14 +1267,14 @@ unsigned long do_mmap(struct file *file, unsigned long addr, if (mlock_future_check(mm, vm_flags, len)) return -EAGAIN; + flags_mask = LEGACY_MAP_MASK; if (file) { struct inode *inode = file_inode(file); - unsigned long flags_mask; if (!file_mmap_ok(file, inode, pgoff, len)) return -EOVERFLOW; - flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; + flags_mask |= file->f_op->mmap_supported_flags; switch (flags & MAP_TYPE) { case MAP_SHARED: @@ -1327,6 +1328,10 @@ unsigned long do_mmap(struct file *file, unsigned long addr, } } else { switch (flags & MAP_TYPE) { + case MAP_SHARED_VALIDATE: + if (flags & ~flags_mask) + return -EOPNOTSUPP; + fallthrough; case MAP_SHARED: if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) return -EINVAL; -- 2.39.2