From: James Morris <jmorris@namei.org>
To: Ben Hutchings <ben@decadent.org.uk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
770492@bugs.debian.org, Ben Harris <bjh21@cam.ac.uk>,
oss-security@lists.openwall.com,
John Johansen <john.johansen@canonical.com>,
Paul Moore <paul@paul-moore.com>,
Stephen Smalley <sds@tycho.nsa.gov>,
Casey Schaufler <casey@schaufler-ca.com>
Subject: Re: [RFC PATCH RESEND] vfs: Move security_inode_killpriv() after permission checks
Date: Wed, 21 Jan 2015 10:17:29 +1100 (AEDT) [thread overview]
Message-ID: <alpine.LRH.2.11.1501211014580.15885@namei.org> (raw)
In-Reply-To: <1421537206.31046.74.camel@decadent.org.uk>
On Sat, 17 Jan 2015, Ben Hutchings wrote:
> chown() and write() should clear all privilege attributes on
> a file - setuid, setgid, setcap and any other extended
> privilege attributes.
>
> However, any attributes beyond setuid and setgid are managed by the
> LSM and not directly by the filesystem, so they cannot be set along
> with the other attributes.
>
> Currently we call security_inode_killpriv() in notify_change(),
> but in case of a chown() this is too early - we have not called
> inode_change_ok() or made any filesystem-specific permission/sanity
> checks.
>
> Add a new function setattr_killpriv() which calls
> security_inode_killpriv() if necessary, and change the setattr()
> implementation to call this in each filesystem that supports xattrs.
> This assumes that extended privilege attributes are always stored in
> xattrs.
It'd be useful to get some input from LSM module maintainers on this.
e.g. doesn't SELinux already handle this via policy directives?
--
James Morris
<jmorris@namei.org>
next prev parent reply other threads:[~2015-01-20 23:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-17 23:26 Ben Hutchings
2015-01-20 23:17 ` James Morris [this message]
2015-01-20 23:32 ` Casey Schaufler
2015-01-21 14:03 ` Stephen Smalley
2015-01-21 16:15 ` Casey Schaufler
2015-02-16 19:50 ` Josh Boyer
2015-04-08 21:43 ` Mateusz Guzik
2015-04-13 1:39 ` James Morris
2015-06-03 17:57 ` Mateusz Guzik
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