setuid file question

[dictum9]

If the file has the ownership of:

-rwSr-----

As far as I understand, that "S" means it's setuid, but what is the point of having setuid if nobody else can execute the file?

[A. Clay Stephenson · Accepted solution]

Actually 'S' as opposed to 's' indicates that no execute bit is set so that this is not, if fact, an executable but a data file. ie. the mode of the file is 4640 rather than 4740. In this case because this is a data file rather than an executable, the setuid bit may be serving as a flag for the application as it has no significance in any other context.

[Rodney Hills]

FYI- And if this is a directory it has a special meaning. If any user could create files under the directory the "S" specifies that only the owners of a file can delete them.

Rod Hills

[A. Clay Stephenson]

Except that it's not a directory and a directory would be especially useless without the search bit enabled for the owner.

[A. Clay Stephenson]

Oh, and even if it were a directory, it's the "sticky" bit (octal 1000) that applies as opposed to the setuid bit (octal 4000). Sorry, Rodney.

[dictum9]

> the setuid bit may be serving as a flag for the application


What do you mean by that?

[James R. Ferguson]

Hi:

The suggetion that "...the setuid bit may be serving as a flag for the application..." derives from a discussion last month wherein it was noted that the SUID bit could serve as a marker for a data file instead of its normal use to confer access rights for an executable. Follow the discussion here:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1015500

Regards!

...JRF...