linux-kernel - Re: [RFC 2/2] fs,proc: Respect FMODE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 22 Apr 2014 17:19:42 +0200
From:	David Herrmann <dh.herrmann@...il.com>
To:	Pavel Machek <pavel@....cz>
Cc:	Andy Lutomirski <luto@...capital.net>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	"Theodore Ts'o" <tytso@....edu>
Subject: Re: [RFC 2/2] fs,proc: Respect FMODE_WRITE when opening /proc/pid/fd/N

Hi

On Tue, Apr 22, 2014 at 4:31 PM, Pavel Machek <pavel@....cz> wrote:
> Such as here?
>
> http://www.securityfocus.com/archive/1/507386

Thanks, that's the first real example someone mentioned.

Quoted from your link:

> The reopen does check the inode permission, but it does not require
> you have any reachable path to the file. Someone _might_ use that as
> a traditional unix security mechanism, but if so it's probably quite rare.

In other words, the bug you describe is that /proc/pid/fd/ allows
access to objects without a reachable path to the only _real_
filesystem link. But isn't the same true for openat()?

Thanks
David
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/