Is there an FSDB Manual?

[Joerg Lehners]

Hello !

bill at pd1.ccd.harris.com (Bill Davis) writes:
>In article <4960 at cbnewsm.ATT.COM> szirin at cbnewsm.ATT.COM writes:
>>
>>Of course, anyone that can figure out how to use fsdb can easily read your
>>private file without ever touching the directory entry...

>If this were true, it would be a nasty security hole.
>Just by knowing fsdb, I could look anywhere in a file
>system and read the contents of files.

No, fsdb is not a security hole. The probabaly world-readable
character and block device special entries in /dev are the security holes.
I know about System V.2 and System V.3. In System V.2 all device
files are public readable to allow df to detremine the free block/inode
count. Maybe there are some other program that need direct filesystem
access.
System V.3 made all these special files unreadable for the normal user.
To determine the blocks/inodes count there s special systemcall.
The same things happened to /dev/mem and /dev/kmem.
System V.2: /dev/mem and /dev/kmem world readable;
System V.3: /dev/mem and /deb/kmem protected and s-bit on /bin/ps (non-root)

When fsdb is a security hole then the files in /usr/include/sys are
all security holes too, and Bach's Book 'The Design Of An Operating
System' is a security hole too. Almost all information to build
an fsdb on your own is in /usr/include/sys/* and some books.

>[a bit deleted]
>.....
>a version of Unix that lets someone other than
>root run fsdb and get information out of it (or
>worse yet, change it), perhaps you might want to tell
>your system vendor about it.  You probably don't
>want your system to remain that way.
Ok, I might be wise to protect fsdb from beeing executed by normal
user's (no problem, I think) to prevent looking at protected files.
But what about a copy of fsdb from somewhere else in some users directory ?

Get a machine and try out protecting the special files for the disks
and memory, and then do the right s-bit setting.

  Joerg
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