[lkml]   [2002]   [May]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: suid bit on directories
    Jesse Pollard writes:
    > Michael Hoennig <>:
    >> [Jesse Pollard???]

    >>> No. You loose the fact that the file was NOT created by the user.
    >> the user in my example above would be wwwrun or httpd - and that does not
    >> make any sense at all! It would make much more sense if the new files
    >> belonged to the owner of the directory, who is the one who owns the
    >> virtual host.
    > You can't tell who the user is. ANY user would be able to do that.

    If you have a setuid directory, then you accept responsibility
    for anything that other people place in that directory.

    If you are the admin, you hold the owner of a setuid directory
    responsible for everything that gets put in it.

    >>>> I do not even see a security hole if nobody other than the user itself
    >>>> and httpd/web can reach this area in the file system, anyway. And it
    >>>> is still the users decision that files in this (his) directory should
    >>>> belong to him.
    >>> 1. users will steal/bypass quota controls
    >> Not in my example - acutally even the other way around.
    > And just how is it prevented? quotas are applied based on either group
    > or user. Normally it is based on user. Once the uid is set, then the
    > quotas start being deducted. If the the user procedes to store 10 G of
    > music files, who is charged? And how do you know who put them there.

    Duh, this is a web server.

    If you really don't understand, then read up on dynamic
    web stuff and web authentication:

    cgi-bin, PHP, WebDAV, Java servlets, SSL...

    >>> 2. Consider what happens if a user creates a file in such a directory
    >>> and it is executable. - since the file is fully owned by a different
    >>> user, it appears to have been created by that user. What protection
    >>> mask is on the file? Can the creator (not owner) make it setuid?
    >>> (nasty worm propagation method)

    Oh please. Do you know that Linux supports a setgid bit
    on directories? Well, it does, just the same as SysV.
    Go ahead, try to get setgid for a group you aren't in.
    Linux will even take away your setuid bit for trying.
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 13:26    [W:0.025 / U:59.988 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site