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SubjectRe: caps in elf, next itteration (the hack get's bigger)

It was my understanding that CAPs substracted privs: I.e.

#ls -l sendmail
-rwsr-sr-x 1 root mail 276044 May 5 1998 sendmail
#listcap sendmail
-all but open root port

So if sometool copied the sendmail bin and understood suid but didn't
understand caps...

#ls -l sendmail
-rwsr-sr-x 1 root mail 276044 May 5 1998 sendmail2
#listcap sendmail2
+all (no caps).

This is not good. Since caps stored in files would be used to limit the
abilities of suid bins, it's important to keep them..

Now if some sysadm were to remove the suid bit on one of the sendmail bins
(because he wants to increase security) that's fine, because the caps dont
ever increase security..

Because of this, it's at best important that caps be in the file, and at
worst not harmful that they are there.



On Sat, 10 Apr 1999, Steffen Zahn wrote:

> The content of executable files never carried around special
> privileges in Unix, they are always stored in metadata. And never
> are such privileges carelessly copied around. Transfer of
> privileges needs careful considerations and itself special
> privileges. For example even if you can read /bin/login as a
> normal user you can not copy its privilege with the file
> content. The only reasonable approach is that all tools and
> transfer protocols, that are not aware of capabilities, erase all
> capabilities by default. This means that default behavior of
> system calls (open,creat etc.) has to be set accordingly. This
> also means that transfer protocols (NFS), that are not aware of
> capabilities, do not transfer capabilities.
>
> Best regards
> Steffen Zahn
>
> --
> home email: user@domain where domain=berlin.snafu.de, user=zahn
> Use of my address for unsolicited commercial advertising is forbidden.
> 2^3021377 - 1 | "Where do you want to crash today?"
>
> -
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