fs: Refuse uid/gid changes which don't map into s_user_ns
Add checks to notify_change to verify that uid and gid changes
will map into the superblock's user namespace. If they do not
fail with -EOVERFLOW.
This is mandatory so that fileystems don't have to even think
of dealing with ia_uid and ia_gid that
--EWB Moved the test from inode_change_ok to notify_change
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/fs/attr.c b/fs/attr.c
index 25b24d0..dd72357 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -255,6 +255,17 @@
if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
return 0;
+ /*
+ * Verify that uid/gid changes are valid in the target
+ * namespace of the superblock.
+ */
+ if (ia_valid & ATTR_UID &&
+ !kuid_has_mapping(inode->i_sb->s_user_ns, attr->ia_uid))
+ return -EOVERFLOW;
+ if (ia_valid & ATTR_GID &&
+ !kgid_has_mapping(inode->i_sb->s_user_ns, attr->ia_gid))
+ return -EOVERFLOW;
+
error = security_inode_setattr(dentry, attr);
if (error)
return error;