Re: securety related question...

* Erika Pacholleck <[email protected]> [2002-10-08 00:08]:
> [07.10.2002] Richard Lightman <-- :
> 
> They are if 1.) you use the remount option for an already mounted
> partition and 2.) you apply it to partitions and not directories.
> 
> > I do not see any harm in mounting a partition ro, and binding a part
> > of it rw somewhere else if that is what I explicitly tell the kernel
> > to do.
> 
> What about a program which uses these kind of bindings arbitrarily and
> then deletes whatever is in it, and before you can do anything just
> starts it(not)self. I'm no programmer but I guess it is possible to
> write a program which withstands a kill signal by catching it and the
> only chance you might have then, would be to pull the power supply.
> If you can tell the kernel explicitly anything else might also, same
> would go for that new `mount --move` command - that's why I think it is
> better not to have this possibility at all.
> 
I do not follow this bit. You cannot assume a file has gone just
because you deleted it. Try this:

cd /var/tmp
seq 1000 >a
cat a | while read i; do echo $i; sleep 1; done
# on another terminal:
cd /var/tmp
rm a
ls


BTW, you cannot prevent the kill signal:
info '(libc)Delivery of Signal'

Richard
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