Re[2]: SECURITY.NNOV: file locking and security (group policy DoS on Windows 2000 domain)

From: 3APA3A (3APA3Aat_private)
Date: Sat Dec 08 2001 - 01:21:45 PST

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    Hello Seth,
    
    I never intended to review all possible locking mechanism. In advisory I
    ment  BSD-compliant  flock()/fcntl()/open()  file locking implemented in
    most unix-like systems.
    
    X/Open  lockf()  mechanism ported to few operation systems requires file
    to be open for writing, so, it's behind advisory (I'm talking about READ
    access).
    
    P.S. I don't use linux.
    
    --Saturday, December 08, 2001, 4:15:48 AM, you wrote to bugtraqat_private:
    
    SA> On Fri, Dec 07, 2001 at 11:57:58AM +0300, 3APA3A wrote:
    >> The way file locks interfere with file access depends on OS. There are 2
    >> possible  situations:  moderate  and  non-moderate  file locks. *BSD and
    >> linux  use  non-moderate  locking, while Windows NT locking is moderate.
    >> What  does it mean? Under Unix file locking is only checked then another
    >> application  tries  to  lock  the  file. If application doesn't use file
    >> locking  it  will  not be affected by file locking.
    
    SA> 3APA3A -- close....
    
    SA> A long-time feature of many Unix systems, including Linux (and probably
    SA> all the BSDs too, but I don't know this for sure) is mandatory file
    SA> locking, implemented in the kernel. It can be turned on using the setgid
    SA> bit on regular files.
    
    SA> Look for Documentation/mandatory.txt in the linux kernel source tree. It
    SA> has all the gory details on mandary file locking, as it is implemented
    SA> in the linux kernel. (Or, was implemented, in 1996.. :)
    
    SA> Cheers!
    
    
    -- 
    ~/ZARAZA
    Ñýð Èñààê Íüþòîí îòêðûë, ÷òî ÿáëîêè ïàäàþò íà çåìëþ. (Òâåí)
    



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