From: Ernesto =?utf-8?Q?A=2E_Fern=C3=A1ndez?= Subject: [PATCH 2/5] ext2: preserve i_mode if ext2_set_acl() fails Date: Wed, 12 Jul 2017 06:54:19 -0300 Message-ID: <099e3ef2bf3a9ab2a1d545b65ba15fad359f2c03.1499805487.git.ernesto.mnd.fernandez@gmail.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit To: Jan Kara , Theodore Ts'o , Andreas Dilger , Dave Kleikamp , linux-ext4@vger.kernel.org, jfs-discussion@lists.sourceforge.net, reiserfs-devel@vger.kernel.org Return-path: Content-Disposition: inline In-Reply-To: Sender: reiserfs-devel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org When changing a file's acl mask, ext2_set_acl() will first set the group bits of i_mode to the value of the mask, and only then set the actual extended attribute representing the new acl. If the second part fails (due to lack of space, for example) and the file had no acl attribute to begin with, the system will from now on assume that the mask permission bits are actual group permission bits, potentially granting access to the wrong users. Prevent this by only changing the inode mode after the acl has been set. Signed-off-by: Ernesto A. Fernández --- A line in acl.c is too long, and checkpatch.pl complains about it when run against this patch. In case it matters, the next patch will fix that. fs/ext2/acl.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/fs/ext2/acl.c b/fs/ext2/acl.c index 79dafa7..4e04b7e 100644 --- a/fs/ext2/acl.c +++ b/fs/ext2/acl.c @@ -185,16 +185,17 @@ ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type) void *value = NULL; size_t size = 0; int error; + int update_mode = 0; + umode_t mode = inode->i_mode; switch(type) { case ACL_TYPE_ACCESS: name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS; if (acl) { - error = posix_acl_update_mode(inode, &inode->i_mode, &acl); + error = posix_acl_update_mode(inode, &mode, &acl); if (error) return error; - inode->i_ctime = current_time(inode); - mark_inode_dirty(inode); + update_mode = 1; } break; @@ -216,8 +217,14 @@ ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type) error = ext2_xattr_set(inode, name_index, "", value, size, 0); kfree(value); - if (!error) + if (!error) { set_cached_acl(inode, type, acl); + if (update_mode) { + inode->i_mode = mode; + inode->i_ctime = current_time(inode); + mark_inode_dirty(inode); + } + } return error; } -- 2.1.4