From: Jann Horn <jann@thejh.net>
To: kernel-hardening@lists.openwall.com
Cc: linux-security-module@vger.kernel.org, keescook@chromium.org,
spender@grsecurity.net, jmorris@namei.org,
casey.schaufler@intel.com, michael.leibowitz@intel.com,
william.c.roberts@intel.com,
Elena Reshetova <elena.reshetova@intel.com>
Subject: Re: [kernel-hardening] [RFC] [PATCH 1/5] path_fchdir and path_fhandle LSM hooks
Date: Fri, 29 Jul 2016 20:12:13 +0200 [thread overview]
Message-ID: <20160729181213.GD11621@pc.thejh.net> (raw)
In-Reply-To: <1469777680-3687-2-git-send-email-elena.reshetova@intel.com>
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On Fri, Jul 29, 2016 at 10:34:36AM +0300, Elena Reshetova wrote:
> This introduces two new LSM hooks operating on paths.
>
> - security_path_fchdir() checks for permission on
> changing working directory. It can be used by
> LSMs concerned on fchdir system call
I don't think security_path_fchdir() is a good abstraction
level. It neither covers the whole case of "cwd is changed" nor does
it cover the whole case of "someone uses a file descriptor to a
directory to look up stuff outside that directory".
For example, security_path_fchdir() seems to be intended to prevent
the use of a leaked file descriptor to the outside world for accessing
other files in the outside world. But this is trivially bypassed by
first using openat() directly instead of fchdir()+open() (something
that used to work against grsecurity, but was fixed quite a while
ago).
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next prev parent reply other threads:[~2016-07-29 18:12 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-29 7:34 [kernel-hardening] [RFC] [PATCH 0/5] Hardchroot LSM + additional hooks Elena Reshetova
2016-07-29 7:34 ` [kernel-hardening] [RFC] [PATCH 1/5] path_fchdir and path_fhandle LSM hooks Elena Reshetova
2016-07-29 18:12 ` Jann Horn [this message]
2016-07-31 10:55 ` Reshetova, Elena
2016-07-31 12:02 ` Jann Horn
2016-07-31 18:28 ` Reshetova, Elena
2016-07-31 21:23 ` Jann Horn
2016-08-01 8:38 ` Reshetova, Elena
2016-07-29 7:34 ` [kernel-hardening] [RFC] [PATCH 2/5] task_unshare LSM hook Elena Reshetova
2016-07-29 17:58 ` Jann Horn
2016-07-29 18:17 ` Reshetova, Elena
2016-07-29 7:34 ` [kernel-hardening] [RFC] [PATCH 3/5] sb_unsharefs " Elena Reshetova
2016-07-29 18:02 ` Jann Horn
2016-07-29 18:09 ` Reshetova, Elena
2016-07-29 18:15 ` Jann Horn
2016-07-29 18:19 ` Reshetova, Elena
2016-07-29 7:34 ` [kernel-hardening] [RFC] [PATCH 4/5] invoke path_chroot() LSM hook on mntns_install() Elena Reshetova
2016-07-29 18:11 ` Jann Horn
2016-07-31 10:39 ` Reshetova, Elena
2016-07-31 11:29 ` Jann Horn
2016-08-01 9:26 ` Reshetova, Elena
2016-07-29 7:34 ` [kernel-hardening] [RFC] [PATCH 5/5] Hardchroot LSM Elena Reshetova
2016-07-29 11:44 ` [kernel-hardening] " Brad Spengler
2016-07-29 12:15 ` [kernel-hardening] " Reshetova, Elena
2016-07-29 12:25 ` Reshetova, Elena
2016-07-29 18:53 ` [kernel-hardening] " Jann Horn
2016-07-29 19:20 ` Casey Schaufler
2016-07-29 20:53 ` Jann Horn
2016-07-29 21:10 ` Casey Schaufler
2016-07-29 21:50 ` Jann Horn
2016-07-30 6:10 ` Reshetova, Elena
2016-08-03 6:36 ` [kernel-hardening] Re: [RFC] [PATCH 0/5] Hardchroot LSM + additional hooks James Morris
2016-08-05 7:53 ` [kernel-hardening] " Reshetova, Elena
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