[Patch 1/2] selinux: ajust rules for ATTR_FORCE

[Amerigo Wang <amwang@redhat.com>]

As suggested by OGAWA Hirofumi in thread: http://lkml.org/lkml/2009/8/7/132,
we should let selinux_inode_setattr() to match our ATTR_* rules.
ATTR_FORCE should not force things like ATTR_SIZE.

Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: WANG Cong <amwang@redhat.com>

---
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 1e8cfc4..3ee3365 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2708,18 +2708,24 @@ static int selinux_inode_permission(struct inode *inode, int mask)
 			      file_mask_to_av(inode->i_mode, mask), NULL);
 }
 
+#define SELINUX_FORCED_MASK	(ATTR_MODE | ATTR_UID | ATTR_GID | \
+				ATTR_ATIME_SET | ATTR_MTIME_SET)
 static int selinux_inode_setattr(struct dentry *dentry, struct iattr *iattr)
 {
 	const struct cred *cred = current_cred();
+	unsigned int ia_valid = iattr->ia_valid;
+	int err = 0;
 
-	if (iattr->ia_valid & ATTR_FORCE)
-		return 0;
-
-	if (iattr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID |
-			       ATTR_ATIME_SET | ATTR_MTIME_SET))
-		return dentry_has_perm(cred, NULL, dentry, FILE__SETATTR);
-
-	return dentry_has_perm(cred, NULL, dentry, FILE__WRITE);
+	if ((ia_valid & ATTR_FORCE) && (ia_valid & SELINUX_FORCED_MASK)) {
+		err = dentry_has_perm(cred, NULL, dentry, FILE__SETATTR);
+		if (err)
+			return err;
+		ia_valid &= ~SELINUX_FORCED_MASK;
+		ia_valid &= ~ATTR_FORCE;
+	}
+	if (ia_valid)
+		err = dentry_has_perm(cred, NULL, dentry, FILE__WRITE);
+	return err;
 }
 
 static int selinux_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)