From: Alexey Izbyshev <izbyshev@ispras.ru>
To: musl@lists.openwall.com
Subject: Re: [musl] Calling setxid() in a vfork()-child
Date: Tue, 13 Oct 2020 19:52:28 +0300 [thread overview]
Message-ID: <422e80eccf76a8937d3528c3cfe52aa2@ispras.ru> (raw)
In-Reply-To: <fcfe55b416f8225de3875699bc126250@ispras.ru>
On 2020-10-12 23:30, Alexey Izbyshev wrote:
> ...However, thinking about it
> more, I see that dropping privileges could open the child to new ways
> of interaction from outside of the app in a window before execve(),
> so, if, say, another unprivileged process can ptrace it at the right
> moment, bad things could happen.
>
Alexander Monakov pointed out to me that this particular naive attack is
not possible (unless "/proc/sys/fs/suid_dumpable" is changed or the
application resets "dumpable" bit via prctl() after setxid()):
https://elixir.bootlin.com/linux/v5.9/source/kernel/cred.c#L466
Alexey
next prev parent reply other threads:[~2020-10-13 16:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-12 9:27 Alexey Izbyshev
2020-10-12 14:55 ` Rich Felker
2020-10-12 20:30 ` Alexey Izbyshev
2020-10-13 2:47 ` Markus Wichmann
2020-10-13 9:52 ` Laurent Bercot
2020-10-13 15:48 ` Alexey Izbyshev
2020-10-13 15:24 ` Alexey Izbyshev
2020-10-13 16:07 ` Rich Felker
2020-10-13 16:52 ` Alexey Izbyshev [this message]
2020-10-13 17:05 ` Rich Felker
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