kern/121559: [patch] [geom] geom label class allows to create inaccessible labels

[Jaakko Heinonen]

>Number:         121559
>Category:       kern
>Synopsis:       [patch] [geom] geom label class allows to create inaccessible labels
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Mar 10 13:10:03 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Jaakko Heinonen
>Release:        7.0-RELEASE / 8.0-CURRENT
>Organization:
>Environment:
>Description:
GEOM label class allows to create labels which are inaccessible through the label names and causes invalid entries to be created under /dev tree. Here are examples of such names:

/ (slash)
/foo (label starting with slash)
foo/ (label ending with slash)
/..bar/.. (label ending with /..)
(empty string)

There's supposedly a code in g_label_is_name_ok() (src/sys/geom/label/g_label.c) that prevents labels ending with "/.." to be created:

       /* Check is the label ends at ../ */
       if ((s = strstr(label, "/..")) != NULL && s[3] == '\0')
                return (0);

However the code is incorrect and it allow for example a label named "/..bar/.." to be created.

Following patch disallows these label names:
- empty labels
- labels starting or ending with '/'
- labels ending with "/.."

The patch also corrects some typos in comments, adds a proper error reporting when invalid labels are tried to create with glabel(8) and corrects a typo in error message.

>How-To-Repeat:
(You need sysutils/e2fsprogs from ports.)

# dd if=/dev/zero of=e2img bs=1M count=10
10+0 records in
10+0 records out
10485760 bytes transferred in 0.334605 secs (31337729 bytes/sec)
# mdconfig -a -t vnode -f e2img
md0
# mke2fs /dev/md0
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: