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 A2332C6FA8E for ; Mon, 27 Feb 2023 02:35:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231653AbjB0CfF (ORCPT ); Sun, 26 Feb 2023 21:35:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231681AbjB0Cep (ORCPT ); Sun, 26 Feb 2023 21:34:45 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7772A1717; Sun, 26 Feb 2023 18:34:00 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id EEED460DC4; Mon, 27 Feb 2023 02:08:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B317EC4339C; Mon, 27 Feb 2023 02:08:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677463726; bh=QoI2PXhqmogKXG3961AQtVobVI5PmRj5LpILM6/Fihg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ufnj2gsfLNlg00BBmFKFQCQnKURc+7iI14NhywfcSg4drKujoOg7YpasoxIlFyC+p PvpE2MKQbV0a153YF0xLqOqbGwO9w8ifdSlQZhTeIqgrH0jRgu9StO42SGW7Pm3yso PRClgqe5O/Y8n6ob691IA0cWhAPsivmkTAxx7kXz+oEy/i0Q9vv/1nTfkxF/khfiOq j3EIyPzCcE0viU+uq+MNLIbKt7Des4Oh2FlFtfq8eXaLUKrCrVp5lYYhuNrGJ1u6Ue uWmqLoOYLktkGcTPRBCLNs5dwDpY9hicE5I+cYkuEL7yTGTDtRIhEue+0qOj83iCau ix8dGXKQ0D0dw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jeff Layton , Boyang Xue , Chuck Lever , Sasha Levin , linux-nfs@vger.kernel.org Subject: [PATCH AUTOSEL 6.1 57/58] nfsd: don't hand out delegation on setuid files being opened for write Date: Sun, 26 Feb 2023 21:04:55 -0500 Message-Id: <20230227020457.1048737-57-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230227020457.1048737-1-sashal@kernel.org> References: <20230227020457.1048737-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jeff Layton [ Upstream commit 826b67e6376c2a788e3a62c4860dcd79500a27d5 ] We had a bug report that xfstest generic/355 was failing on NFSv4.0. This test sets various combinations of setuid/setgid modes and tests whether DIO writes will cause them to be stripped. What I found was that the server did properly strip those bits, but the client didn't notice because it held a delegation that was not recalled. The recall didn't occur because the client itself was the one generating the activity and we avoid recalls in that case. Clearing setuid bits is an "implicit" activity. The client didn't specifically request that we do that, so we need the server to issue a CB_RECALL, or avoid the situation entirely by not issuing a delegation. The easiest fix here is to simply not give out a delegation if the file is being opened for write, and the mode has the setuid and/or setgid bit set. Note that there is a potential race between the mode and lease being set, so we test for this condition both before and after setting the lease. This patch fixes generic/355, generic/683 and generic/684 for me. (Note that 355 fails only on v4.0, and 683 and 684 require NFSv4.2 to run and fail). Reported-by: Boyang Xue Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/nfs4state.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 2247d107da90b..925a963aea00f 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -5397,6 +5397,23 @@ nfsd4_verify_deleg_dentry(struct nfsd4_open *open, struct nfs4_file *fp, return 0; } +/* + * We avoid breaking delegations held by a client due to its own activity, but + * clearing setuid/setgid bits on a write is an implicit activity and the client + * may not notice and continue using the old mode. Avoid giving out a delegation + * on setuid/setgid files when the client is requesting an open for write. + */ +static int +nfsd4_verify_setuid_write(struct nfsd4_open *open, struct nfsd_file *nf) +{ + struct inode *inode = file_inode(nf->nf_file); + + if ((open->op_share_access & NFS4_SHARE_ACCESS_WRITE) && + (inode->i_mode & (S_ISUID|S_ISGID))) + return -EAGAIN; + return 0; +} + static struct nfs4_delegation * nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, struct svc_fh *parent) @@ -5430,6 +5447,8 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, spin_lock(&fp->fi_lock); if (nfs4_delegation_exists(clp, fp)) status = -EAGAIN; + else if (nfsd4_verify_setuid_write(open, nf)) + status = -EAGAIN; else if (!fp->fi_deleg_file) { fp->fi_deleg_file = nf; /* increment early to prevent fi_deleg_file from being @@ -5470,6 +5489,14 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, if (status) goto out_unlock; + /* + * Now that the deleg is set, check again to ensure that nothing + * raced in and changed the mode while we weren't lookng. + */ + status = nfsd4_verify_setuid_write(open, fp->fi_deleg_file); + if (status) + goto out_unlock; + spin_lock(&state_lock); spin_lock(&fp->fi_lock); if (fp->fi_had_conflict) -- 2.39.0