From: Matthias Urlichs <matthias@urlichs.de>
To: wireguard@lists.zx2c4.com
Subject: Re: Openbsd update recommendation
Date: Sat, 2 Jun 2018 13:56:33 +0200 [thread overview]
Message-ID: <5eef1dc6-2f95-a15e-731d-bab2baa290a5@urlichs.de> (raw)
In-Reply-To: <CAHmME9p7ZkaJO7FYTbyp39tQAKtfZhkD_5Lo5TfQpiOkM1a3kA@mail.gmail.com>
On 02.06.2018 05:15, Jason A. Donenfeld wrote:
> # ksh -c pwd
> /root/a
>
> That's pretty weird behavior, but maybe there's an interesting reason
> for it
Yes.
# mv ../a ../xx
# /bin/pwd
Basically you have three choices, (a) check whether $PWD points to the
current directory, (b) reconstruct the current path by walking up and
"readdir()" on each level, (c) ask the kernel.
In order to make some interesting attacks via symlinks more difficult,
(b) is somewhat safer. However, it's also significantly more expensive.
(c) works on Linux, just readlink("/proc/self/cwd"); it's equivalent to
(b). I don't know whether OpenBSD can do that, though.
--
-- Matthias Urlichs
prev parent reply other threads:[~2018-06-02 11:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-01 23:26 jungle Boogie
2018-06-02 3:15 ` Jason A. Donenfeld
2018-06-02 7:08 ` Jungle Boogie
2018-06-02 14:39 ` Jason A. Donenfeld
2018-06-02 20:07 ` Jungle Boogie
2018-06-02 11:56 ` Matthias Urlichs [this message]
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