linux-kernel - [PATCH 3.16 124/192] jfs: Don't clear SGID when inheriting ACLs

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Message-ID: <lsq.1507553064.376114980@decadent.org.uk>
Date:   Mon, 09 Oct 2017 13:44:24 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Dave Kleikamp" <dave.kleikamp@...cle.com>,
        jfs-discussion@...ts.sourceforge.net, "Jan Kara" <jack@...e.cz>
Subject: [PATCH 3.16 124/192] jfs: Don't clear SGID when inheriting ACLs

3.16.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@...e.cz>

commit 9bcf66c72d726322441ec82962994e69157613e4 upstream.

When new directory 'DIR1' is created in a directory 'DIR0' with SGID bit
set, DIR1 is expected to have SGID bit set (and owning group equal to
the owning group of 'DIR0'). However when 'DIR0' also has some default
ACLs that 'DIR1' inherits, setting these ACLs will result in SGID bit on
'DIR1' to get cleared if user is not member of the owning group.

Fix the problem by moving posix_acl_update_mode() out of
__jfs_set_acl() into jfs_set_acl(). That way the function will not be
called when inheriting ACLs which is what we want as it prevents SGID
bit clearing and the mode has been properly set by posix_acl_create()
anyway.

Fixes: 073931017b49d9458aa351605b43a7e34598caef
CC: jfs-discussion@...ts.sourceforge.net
Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Dave Kleikamp <dave.kleikamp@...cle.com>
[bwh: Backported to 3.16:
 - Keep using CURRENT_TIME
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/jfs/acl.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

--- a/fs/jfs/acl.c
+++ b/fs/jfs/acl.c
@@ -83,13 +83,6 @@ static int __jfs_set_acl(tid_t tid, stru
 	switch (type) {
 	case ACL_TYPE_ACCESS:
 		ea_name = POSIX_ACL_XATTR_ACCESS;
-		if (acl) {
-			rc = posix_acl_update_mode(inode, &inode->i_mode, &acl);
-			if (rc)
-				return rc;
-			inode->i_ctime = CURRENT_TIME;
-			mark_inode_dirty(inode);
-		}
 		break;
 	case ACL_TYPE_DEFAULT:
 		ea_name = POSIX_ACL_XATTR_DEFAULT;
@@ -124,9 +117,17 @@ int jfs_set_acl(struct inode *inode, str
 
 	tid = txBegin(inode->i_sb, 0);
 	mutex_lock(&JFS_IP(inode)->commit_mutex);
+	if (type == ACL_TYPE_ACCESS && acl) {
+		rc = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+		if (rc)
+			goto end_tx;
+		inode->i_ctime = CURRENT_TIME;
+		mark_inode_dirty(inode);
+	}
 	rc = __jfs_set_acl(tid, inode, type, acl);
 	if (!rc)
 		rc = txCommit(tid, 1, &inode, 0);
+end_tx:
 	txEnd(tid);
 	mutex_unlock(&JFS_IP(inode)->commit_mutex);
 	return rc;