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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AC30AC432C0 for ; Tue, 19 Nov 2019 18:41:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A41822409 for ; Tue, 19 Nov 2019 18:41:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574188871; bh=3m7sna6+G+TQL2w+vr9AGbmik1zbuRAz/wJpe/P3i6Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=fV2g2syMgyp5phOcTdLNFIF8g/QReCLLWOUulqzALAdxBirfZA99Ot/TNSTPyXIiW PCF3e3NaB9hqvVQ8ESb8ysWPpphS1nvSDCDDvIX6yl4rrvdro/tJfc+HvOKxNxrjoI Y7/DrNqdKPB8oiPhdPQotqiehMvwR0dVw5dWkcYY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727450AbfKSSlH (ORCPT ); Tue, 19 Nov 2019 13:41:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:52826 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727205AbfKSSlG (ORCPT ); Tue, 19 Nov 2019 13:41:06 -0500 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 40E6422409; Tue, 19 Nov 2019 18:41:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574188866; bh=3m7sna6+G+TQL2w+vr9AGbmik1zbuRAz/wJpe/P3i6Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oAGrncSLLMav3KH009Hn91MYEcG3QZYlOy9gCkO4ViFtZqwknzcxVMH9HxMmYruN/ ljeSnoc6en8McivZisV03omqYhbqL1Vl5IljpFmCWETsqtOdyAdV8bBlnPxvQdgFTV u7c/poT6uNg7/5ubDDfOsEf1lRvIUA5ytm8UVzyk= From: Will Deacon To: selinux@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Will Deacon Subject: [RFC PATCH 2/2] selinux: Propagate RCU walk status from 'security_inode_follow_link()' Date: Tue, 19 Nov 2019 18:40:57 +0000 Message-Id: <20191119184057.14961-3-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191119184057.14961-1-will@kernel.org> References: <20191119184057.14961-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org 'selinux_inode_follow_link()' can be called as part of an RCU path walk, and is passed a 'bool rcu' parameter to indicate whether or not it is being called from within an RCU read-side critical section. Unfortunately, this knowledge is not propagated further and, instead, 'avc_has_perm()' unconditionally passes a flags argument of '0' to both 'avc_has_perm_noaudit()' and 'avc_audit()' which may block. Introduce 'avc_has_perm_flags()' which can be used safely from within an RCU read-side critical section. Signed-off-by: Will Deacon --- security/selinux/avc.c | 12 +++++++----- security/selinux/hooks.c | 5 +++-- security/selinux/include/avc.h | 12 ++++++++---- 3 files changed, 18 insertions(+), 11 deletions(-) diff --git a/security/selinux/avc.c b/security/selinux/avc.c index 9c183c899e92..7d99dadd24d0 100644 --- a/security/selinux/avc.c +++ b/security/selinux/avc.c @@ -1177,11 +1177,12 @@ inline int avc_has_perm_noaudit(struct selinux_state *state, } /** - * avc_has_perm - Check permissions and perform any appropriate auditing. + * avc_has_perm_flags - Check permissions and perform any appropriate auditing. * @ssid: source security identifier * @tsid: target security identifier * @tclass: target security class * @requested: requested permissions, interpreted based on @tclass + * @flags: AVC_STRICT, AVC_NONBLOCKING, or 0 * @auditdata: auxiliary audit data * * Check the AVC to determine whether the @requested permissions are granted @@ -1192,17 +1193,18 @@ inline int avc_has_perm_noaudit(struct selinux_state *state, * permissions are granted, -%EACCES if any permissions are denied, or * another -errno upon other errors. */ -int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass, - u32 requested, struct common_audit_data *auditdata) +int avc_has_perm_flags(struct selinux_state *state, u32 ssid, u32 tsid, + u16 tclass, u32 requested, unsigned int flags, + struct common_audit_data *auditdata) { struct av_decision avd; int rc, rc2; - rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0, + rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, flags, &avd); rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc, - auditdata, 0); + auditdata, flags); if (rc2) return rc2; return rc; diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 9625b99e677f..0c09f59a2740 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3008,8 +3008,9 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct inode *inode, if (IS_ERR(isec)) return PTR_ERR(isec); - return avc_has_perm(&selinux_state, - sid, isec->sid, isec->sclass, FILE__READ, &ad); + return avc_has_perm_flags(&selinux_state, sid, isec->sid, isec->sclass, + rcu ? AVC_NONBLOCKING : 0, + FILE__READ, &ad); } static noinline int audit_inode_permission(struct inode *inode, diff --git a/security/selinux/include/avc.h b/security/selinux/include/avc.h index 7be0e1e90e8b..0450e1b88182 100644 --- a/security/selinux/include/avc.h +++ b/security/selinux/include/avc.h @@ -149,10 +149,14 @@ int avc_has_perm_noaudit(struct selinux_state *state, unsigned flags, struct av_decision *avd); -int avc_has_perm(struct selinux_state *state, - u32 ssid, u32 tsid, - u16 tclass, u32 requested, - struct common_audit_data *auditdata); +int avc_has_perm_flags(struct selinux_state *state, + u32 ssid, u32 tsid, + u16 tclass, u32 requested, + unsigned flags, + struct common_audit_data *auditdata); + +#define avc_has_perm(state, ssid, tsid, tclass, requested, auditdata) \ + avc_has_perm_flags(state, ssid, tsid, tclass, requested, 0, auditdata) int avc_has_extended_perms(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass, u32 requested, -- 2.24.0.432.g9d3f5f5b63-goog