[PATCH 3.2 50/74] ext3: Don't clear SGID when inheriting ACLs

[Ben Hutchings]

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

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

From: Ben Hutchings <b...@decadent.org.uk>

Based on Jan Kara's fix for ext2 (commit a992f2d38e4c), from which the
following description is taken:

> 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 creating __ext2_set_acl() function that does not call
> posix_acl_update_mode() and use it when inheriting ACLs. That prevents
> SGID bit clearing and the mode has been properly set by
> posix_acl_create() anyway.

Fixes: 073931017b49 ("posix_acl: Clear SGID bit when setting file permissions")
Cc: linux-e...@vger.kernel.org
Cc: Jan Kara <j...@suse.cz>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 fs/ext3/acl.c | 36 ++++++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 14 deletions(-)

--- a/fs/ext3/acl.c
+++ b/fs/ext3/acl.c
@@ -178,14 +178,9 @@ ext3_get_acl(struct inode *inode, int ty
        return acl;
 }
 
-/*
- * Set the access or default ACL of an inode.
- *
- * inode->i_mutex: down unless called from ext3_new_inode
- */
 static int
-ext3_set_acl(handle_t *handle, struct inode *inode, int type,
-            struct posix_acl *acl)
+__ext3_set_acl(handle_t *handle, struct inode *inode, int type,
+              struct posix_acl *acl)
 {
        int name_index;
        void *value = NULL;
@@ -198,13 +193,6 @@ ext3_set_acl(handle_t *handle, struct in
        switch(type) {
                case ACL_TYPE_ACCESS:
                        name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
-                       if (acl) {
-                               error = posix_acl_update_mode(inode, 
&inode->i_mode, &acl);
-                               if (error)
-                                       return error;
-                               inode->i_ctime = CURRENT_TIME_SEC;
-                               ext3_mark_inode_dirty(handle, inode);
-                       }
                        break;
 
                case ACL_TYPE_DEFAULT:
@@ -234,6 +222,27 @@ ext3_set_acl(handle_t *handle, struct in
 }
 
 /*
+ * Set the access or default ACL of an inode.
+ *
+ * inode->i_mutex: down
+ */
+static int
+ext3_set_acl(handle_t *handle, struct inode *inode, int type,
+            struct posix_acl *acl)
+{
+       int error;
+
+       if (type == ACL_TYPE_ACCESS && acl) {
+               error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+               if (error)
+                       return error;
+               inode->i_ctime = CURRENT_TIME_SEC;
+               ext3_mark_inode_dirty(handle, inode);
+       }
+       return __ext3_set_acl(handle, inode, type, acl);
+}
+
+/*
  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
  *
  * dir->i_mutex: down
@@ -256,8 +265,8 @@ ext3_init_acl(handle_t *handle, struct i
        }
        if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
                if (S_ISDIR(inode->i_mode)) {
-                       error = ext3_set_acl(handle, inode,
-                                            ACL_TYPE_DEFAULT, acl);
+                       error = __ext3_set_acl(handle, inode,
+                                              ACL_TYPE_DEFAULT, acl);
                        if (error)
                                goto cleanup;
                }
@@ -267,7 +276,7 @@ ext3_init_acl(handle_t *handle, struct i
 
                if (error > 0) {
                        /* This is an extended ACL */
-                       error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, 
acl);
+                       error = __ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, 
acl);
                }
        }
 cleanup: