From patchwork Tue May 2 13:36:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 13228926 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 C8DD0C77B73 for ; Tue, 2 May 2023 13:36:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234212AbjEBNg3 (ORCPT ); Tue, 2 May 2023 09:36:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234299AbjEBNg0 (ORCPT ); Tue, 2 May 2023 09:36:26 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7DCFD6A5A for ; Tue, 2 May 2023 06:36:15 -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 dfw.source.kernel.org (Postfix) with ESMTPS id C182462480 for ; Tue, 2 May 2023 13:36:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 94D39C4339C; Tue, 2 May 2023 13:36:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683034574; bh=cREU9j+BYCVPtChZc46xMyHx5WzMy5qtAL1TmQg1vgU=; h=From:To:Cc:Subject:Date:From; b=Uh/ft862Wdbet1pnQFLpFUNyQ5lN9Fix2MTfuPtDqb/oNI+AwUJZ5VWaqwP9S34TC hHKjF1N0fx9EZnNCzYYaJLN8NFpGqqSRI6phVlN5HvtepXywK8ajm+uLlcN4yKV0gA TbFF4fiqLu55DZOw5hLzSpLxzUCI3Crbrwsw0v0bYX2WcguzrB804GQpJ206JFBgCT fiUJV5dn5Wn3vFlOiMrQUbpbPWmeOIkdBdO/dhgHI9pw6TGBVIMTZ2l7MCBUvBbeF/ aHi6Kwb2nfMBjBbP+7gYsT8HQoPPj1nYzh4fhCwk+pr/wV+WW5f9l+7RTb0hpIpbi7 ul/pDBtz2hllA== From: Christian Brauner To: Chuck Lever , Jeff Layton Cc: Christian Brauner , linux-nfs@vger.kernel.org, Sherry Yang Subject: [PATCH] nfsd: use vfs setgid helper Date: Tue, 2 May 2023 15:36:02 +0200 Message-Id: <20230502-agenda-regeln-04d2573bd0fd@brauner> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2712; i=brauner@kernel.org; h=from:subject:message-id; bh=cREU9j+BYCVPtChZc46xMyHx5WzMy5qtAL1TmQg1vgU=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMaQECjyOftpsf/hxUXfloRgn6xcXs37XZj7ecZpnrcgjg3pR b0GnjlIWBjEuBlkxRRaHdpNwueU8FZuNMjVg5rAygQxh4OIUgIkYL2RkmPc7Q3fP/1UztH1ueQSa6W iFHtiR1FL32nzL/xXT4mNX/mL4XzrrrLq3zXoZ9bA3TALfF6dZTdmizH71xr3oxb4Vpuc5WAE= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org We've aligned setgid behavior over multiple kernel releases. The details can be found in commit cf619f891971 ("Merge tag 'fs.ovl.setgid.v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping") and commit 426b4ca2d6a5 ("Merge tag 'fs.setgid.v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux"). Consistent setgid stripping behavior is now encapsulated in the setattr_should_drop_sgid() helper which is used by all filesystems that strip setgid bits outside of vfs proper. Usually ATTR_KILL_SGID is raised in e.g., chown_common() and is subject to the setattr_should_drop_sgid() check to determine whether the setgid bit can be retained. Since nfsd is raising ATTR_KILL_SGID unconditionally it will cause notify_change() to strip it even if the caller had the necessary privileges to retain it. Ensure that nfsd only raises ATR_KILL_SGID if the caller lacks the necessary privileges to retain the setgid bit. Without this patch the setgid stripping tests in LTP will fail: > As you can see, the problem is S_ISGID (0002000) was dropped on a > non-group-executable file while chown was invoked by super-user, while [...] > fchown02.c:66: TFAIL: testfile2: wrong mode permissions 0100700, expected 0102700 [...] > chown02.c:57: TFAIL: testfile2: wrong mode permissions 0100700, expected 0102700 With this patch all tests pass. Reported-by: Sherry Yang Signed-off-by: Christian Brauner Reviewed-by: Jeff Layton --- ubuntu@imp1-vm:~/ltp-install$ sudo ./runltp -d /mnt -s chown02 INFO: ltp-pan reported all tests PASS LTP Version: 20230127-112-gf41e8a2fa ubuntu@imp1-vm:~/ltp-install$ sudo ./runltp -d /mnt -s fchown02 INFO: ltp-pan reported all tests PASS LTP Version: 20230127-112-gf41e8a2fa ubuntu@imp1-vm:~/src/git/xfstests$ sudo ./check -g perms FSTYP -- nfs PLATFORM -- Linux/x86_64 imp1-vm 6.3.0-nfs-setgid-3a3cfe624076 #20 SMP PREEMPT_DYNAMIC Tue May 2 12:35:51 UTC 2023 MKFS_OPTIONS -- 127.0.0.1:/nfsscratch MOUNT_OPTIONS -- -o vers=3,noacl 127.0.0.1:/nfsscratch /mnt/scratch Passed all 41 tests --- fs/nfsd/vfs.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index bb9d47172162..c4ef24c5ffd0 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -388,7 +388,9 @@ nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap) iap->ia_mode &= ~S_ISGID; } else { /* set ATTR_KILL_* bits and let VFS handle it */ - iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID); + iap->ia_valid |= ATTR_KILL_SUID; + iap->ia_valid |= + setattr_should_drop_sgid(&nop_mnt_idmap, inode); } } }