Re: [PATCH] new syscall: flink

[Vitaly]

On 7 Apr 2003 06:43:40 GMT
[e-mail] (David Wagner) wrote:

> H. Peter Anvin wrote:
> >Here is a better piece of sample code that actually shows a
> >permissions violation happening:
> >
> >[...]
> >mkdir("testdir", 0700)                  = 0
> >open("testdir/testfile", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3
> >write(3, "Ansiktsburk\n", 12)           = 12
> >close(3)                                = 0
> >open("testdir/testfile", O_RDONLY)      = 3
> >chmod("testdir", 0)                     = 0
> >open("/proc/self/fd/3", O_RDWR)         = 4
> >write(4, "Tjo fidelittan hatt!\n", 21)  = 21
> 
> You're right!  Good point. I retract the comments in my previous email.
> (I did try an experiment like this, but apparently not the right one.)
> 
> My conclusion: /proc/*/fd is a security hole.  It should be fixed.
> Do you agree?
open("/proc/self/fd/3", O_RDWR) -- i thought, it just makes a copy for fd/3, and fd/3 should have the same permissions as it was opened.

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