From e4234d2c74ebfbac18198a14943d45b913649f78 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ernesto=20A=2E=20Fern=C3=A1ndez?= Date: Sun, 30 Jul 2017 22:43:41 -0400 Subject: [PATCH] ext4: preserve i_mode if __ext4_set_acl() fails MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit 397e434176bb62bc6068d2210af1d876c6212a7e upstream. When changing a file's acl mask, __ext4_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 Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- fs/ext4/acl.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c index 5d419a496d96d..b060bce2a67ff 100644 --- a/fs/ext4/acl.c +++ b/fs/ext4/acl.c @@ -190,6 +190,8 @@ ext4_set_acl(handle_t *handle, struct inode *inode, int type, void *value = NULL; size_t size = 0; int error; + int update_mode = 0; + umode_t mode = inode->i_mode; if (S_ISLNK(inode->i_mode)) return -EOPNOTSUPP; @@ -198,11 +200,10 @@ ext4_set_acl(handle_t *handle, struct inode *inode, int type, case ACL_TYPE_ACCESS: name_index = EXT4_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 = ext4_current_time(inode); - ext4_mark_inode_dirty(handle, inode); + update_mode = 1; } break; @@ -225,8 +226,14 @@ ext4_set_acl(handle_t *handle, struct inode *inode, int type, 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 = ext4_current_time(inode); + ext4_mark_inode_dirty(handle, inode); + } + } return error; } -- 2.47.3