From patchwork Thu Sep 29 15:30:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12994269 X-Patchwork-Delegate: paul@paul-moore.com 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 48D99C4332F for ; Thu, 29 Sep 2022 15:34:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235224AbiI2Per (ORCPT ); Thu, 29 Sep 2022 11:34:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235259AbiI2Pc5 (ORCPT ); Thu, 29 Sep 2022 11:32:57 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D1B0177341; Thu, 29 Sep 2022 08:32:01 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 3DD46B824F2; Thu, 29 Sep 2022 15:32:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 044E8C4347C; Thu, 29 Sep 2022 15:31:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664465519; bh=TALios6GJy/9Xg/rNe0HSqPJhJrlpV6C67TbXwjDa+8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ExF8x3nsS76oZRnO6pNjzcwx8w+G2yS27REl7tsMNAYd3kdvacOZeEnPTpYo8LWZ8 lnI24p5qGoGhGf6E1gZcb7KBKcFg0L7nNaC+OXUMP45aTl9vrEHmkDQk70o/Dx1LCC RJn1609WJKQVB3cFhU7Df+YwzQizcm1+Dkw08iRjwYSazIHYFg3G553f6ANmX75h07 H+DFC2heacb80xaUeo5pLw0hKtVqOGVsTOjEeDzFMnhy2FXWpHVv32VBL4rZov8Pc0 5jjuyfcA47MPC2gFJhba2UssBc8d9pCqKZEiW4kzRXNBCz118aFqXTXRVHb7qDrQr3 /nxsN0X0KfkpQ== From: Christian Brauner To: linux-fsdevel@vger.kernel.org Cc: Christian Brauner , Seth Forshee , Christoph Hellwig , Al Viro , Mimi Zohar , linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, Paul Moore Subject: [PATCH v4 25/30] evm: remove evm_xattr_acl_change() Date: Thu, 29 Sep 2022 17:30:35 +0200 Message-Id: <20220929153041.500115-26-brauner@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220929153041.500115-1-brauner@kernel.org> References: <20220929153041.500115-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3891; i=brauner@kernel.org; h=from:subject; bh=TALios6GJy/9Xg/rNe0HSqPJhJrlpV6C67TbXwjDa+8=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMSSb7hJjkbOt/fZYhnsH4+GWnN6v2S7M3U9ebDqyu/N4i6eR 0bGvHaUsDGJcDLJiiiwO7Sbhcst5KjYbZWrAzGFlAhnCwMUpABNhcWL4p9k0c8cl/0X8i28tffh7dk u+6ctmYY+OkgZdU1fT7BCjGEaGjsQW/SxrXv3+rliWyqKmXS8mHfJ0MJBJFc52K95efJcJAA== X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: The security and integrity infrastructure has dedicated hooks now so evm_xattr_acl_change() is dead code. Before this commit the callchain was: evm_protect_xattr() -> evm_xattr_change() -> evm_xattr_acl_change() where evm_protect_xattr() was hit from evm_inode_setxattr() and evm_inode_removexattr(). But now we have evm_inode_set_acl() and evm_inode_remove_acl() and have switched over the vfs to rely on the posix acl api so the code isn't hit anymore. Suggested-by: Paul Moore Signed-off-by: Christian Brauner (Microsoft) --- Notes: /* v2 */ unchanged /* v3 */ Paul Moore : - Remove evm_xattr_acl_change() completely. /* v4 */ unchanged security/integrity/evm/evm_main.c | 64 ------------------------------- 1 file changed, 64 deletions(-) diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 7904786b610f..e0d120383870 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -434,66 +434,6 @@ static enum integrity_status evm_verify_current_integrity(struct dentry *dentry) return evm_verify_hmac(dentry, NULL, NULL, 0, NULL); } -/* - * evm_xattr_acl_change - check if passed ACL changes the inode mode - * @mnt_userns: user namespace of the idmapped mount - * @dentry: pointer to the affected dentry - * @xattr_name: requested xattr - * @xattr_value: requested xattr value - * @xattr_value_len: requested xattr value length - * - * Check if passed ACL changes the inode mode, which is protected by EVM. - * - * Returns 1 if passed ACL causes inode mode change, 0 otherwise. - */ -static int evm_xattr_acl_change(struct user_namespace *mnt_userns, - struct dentry *dentry, const char *xattr_name, - const void *xattr_value, size_t xattr_value_len) -{ -#ifdef CONFIG_FS_POSIX_ACL - umode_t mode; - struct posix_acl *acl = NULL, *acl_res; - struct inode *inode = d_backing_inode(dentry); - int rc; - - /* - * An earlier comment here mentioned that the idmappings for - * ACL_{GROUP,USER} don't matter since EVM is only interested in the - * mode stored as part of POSIX ACLs. Nonetheless, if it must translate - * from the uapi POSIX ACL representation to the VFS internal POSIX ACL - * representation it should do so correctly. There's no guarantee that - * we won't change POSIX ACLs in a way that ACL_{GROUP,USER} matters - * for the mode at some point and it's difficult to keep track of all - * the LSM and integrity modules and what they do to POSIX ACLs. - * - * Frankly, EVM shouldn't try to interpret the uapi struct for POSIX - * ACLs it received. It requires knowledge that only the VFS is - * guaranteed to have. - */ - acl = vfs_set_acl_prepare(mnt_userns, i_user_ns(inode), - xattr_value, xattr_value_len); - if (IS_ERR_OR_NULL(acl)) - return 1; - - acl_res = acl; - /* - * Passing mnt_userns is necessary to correctly determine the GID in - * an idmapped mount, as the GID is used to clear the setgid bit in - * the inode mode. - */ - rc = posix_acl_update_mode(mnt_userns, inode, &mode, &acl_res); - - posix_acl_release(acl); - - if (rc) - return 1; - - if (inode->i_mode != mode) - return 1; -#endif - return 0; -} - /* * evm_xattr_change - check if passed xattr value differs from current value * @mnt_userns: user namespace of the idmapped mount @@ -513,10 +453,6 @@ static int evm_xattr_change(struct user_namespace *mnt_userns, char *xattr_data = NULL; int rc = 0; - if (posix_xattr_acl(xattr_name)) - return evm_xattr_acl_change(mnt_userns, dentry, xattr_name, - xattr_value, xattr_value_len); - rc = vfs_getxattr_alloc(&init_user_ns, dentry, xattr_name, &xattr_data, 0, GFP_NOFS); if (rc < 0)