From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 0ABA0522EF5; Thu, 17 Sep 2026 17:25:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789665931; cv=none; b=ZjxrBE68/yJ/RPZf+aXaeSIb/Wn3pY71XFgiPrMcxr3zzxu+Ll9Kw6JDw0vpZvL0C+9OD8FsC8knneCbLvSqYRD+9uBN/yoNxo+eU7Zifjh8cmWxuO9gIiWsifHqPBxEBq7mpJevKH7JCjvZQMwSxNemtRqpbwLgaUJeQhbO+nE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789665931; c=relaxed/simple; bh=z67KlTeWdWUfckdrR3+nSagyP8g7QLmUq4qSmxvPpiU=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=CUNS5U4PpTqJGgW15kOn4nKCjImxDD1ChwZ62+l0oINhWPJgB7RW14Ov+qlCs2uzzh1qvMLyfTtAarNcmGlAs2UGaOtJl/fdgwSCtddhKz0cefQAjdKftCPLkckDfvZ2Z68/VHyw8UzJ3Bv59z5IBBxxXrsPC8lNzV4prrgAThU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DNP1bLwf; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DNP1bLwf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0365D1F00898; Thu, 17 Sep 2026 17:25:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789665929; bh=z67KlTeWdWUfckdrR3+nSagyP8g7QLmUq4qSmxvPpiU=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=DNP1bLwfXsSv7FB5Dqn1iXc9cwqzYVpipsMv/WqB+Liau2yasgds0BzoUsIMzpPD+ PlkJTOSTmZzDUTa37vRHRMlPf8fRc2uhyHJUlTXH/VA61WFVEJ2U1mZZr6r+TR7tGx ZpPCB3FLAat7SZ4qz+3PmCsqVOLMc+wQBajrWmHe3C1Jh87ulDaan82s3vn7DCQr1t J0oIAO3HvTUzRNM9czotxmUPVtEbxrUaVt4i3lsAtHf94Qk8SaSorDkxts1xKQ92Ey PQfmYQ143EX/ToZRDC4sdsE1WMgsddVdSDpQehSuKM3w7cR0ziqFtbkEuWlKLgYkBO NY578Lh+qCkxA== From: sashiko-bot@kernel.org Subject: Re: [PATCH v3 12/40] selinux: reject writable opens of policy file, drop mmap shared/write check Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?TG9yZW56byBTdG9ha2VzIChBUk0p?= Cc: "Oliver Upton" , linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, selinux@vger.kernel.org, "Vasily Gorbik" , "Christian Borntraeger" , kvm@vger.kernel.org, linux-scsi@vger.kernel.org, kvmarm@lists.linux.dev, linux-rdma@vger.kernel.org, "Marc Zyngier" , "Alexander Gordeev" , dri-devel@lists.freedesktop.org, linux-perf-users@vger.kernel.org, bpf@vger.kernel.org, "Heiko Carstens" In-Reply-To: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-12-4583d8a23bca@kernel.org> References: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org> <20260917-b4-mmap-prepare-vma-flag-sanify-v3-12-4583d8a23bca@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 17 Sep 2026 17:25:28 +0000 Message-Id: <20260917172529.0365D1F00898@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > The policy file has no write method and is exposed read-only (S_IRUGO in > selinux_files[]), yet sel_open_policy() performs no open mode check, so a > CAP_DAC_OVERRIDE caller can open it O_RDWR. Reject FMODE_WRITE at open, as > kernfs does. >=20 > The file can then never be mapped with FMODE_WRITE, so do_mmap() always > clears VM_MAYWRITE and VM_SHARED for MAP_SHARED mappings and the VM_SHARED > check in sel_mmap_policy() cannot be reached. Remove it. >=20 > This also stops sel_mmap_policy() clearing VM_MAYWRITE on a mapping that = is > neither a PFN map nor a mixed map, ahead of the core enforcing that only > such mappings may do so. >=20 > Acked-by: Stephen Smalley > Reviewed-by: Jann Horn > Acked-by: Paul Moore > Signed-off-by: Lorenzo Stoakes (ARM) Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260917-b4-mmap-pr= epare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org?part=3D12