Re: /proc filesystem allows bypassing directory permissions on Linux

[Pavel Machek <pavel () ucw cz>]

On Mon 2009-10-26 13:42:17, Dan Yefimov wrote:
> On 25.10.2009 2:40, psz () maths usyd edu au wrote:
> > Dear Pavel,
> >
> > > ... that's exactly the problem.
> >
> > I see, the /proc/*/fd/* objects seem "confused": are they symlinks,
> > hardlinks, or open file descriptors? I guess should always act as
> > the latter, where access mode flags (O_RDONLY or O_RDWR) are set at
> > open() and not changeable afterwards in fcntl(). Any open() on them
> > should behave as a dup().
> Paul, in authentic kernels /proc/<PID>/fd/<FD> are symlinks, not
> anything other. There're no such publicly accessible file objects,
> as file descriptors, there're only files (including special ones),
> directories and symlinks. But the above words don't necessary relate
> to patched kernels like distributed by third parties.

Check your facts. Those symlinks are special.
                                                                        Pavel
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