linux-kernel - Re: [RFC PATCH RESEND] vfs: Move security_inode

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]

Message-ID: <alpine.LRH.2.11.1501211014580.15885@namei.org>
Date:	Wed, 21 Jan 2015 10:17:29 +1100 (AEDT)
From:	James Morris <jmorris@...ei.org>
To:	Ben Hutchings <ben@...adent.org.uk>
cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>, 770492@...s.debian.org,
	Ben Harris <bjh21@....ac.uk>, oss-security@...ts.openwall.com,
	John Johansen <john.johansen@...onical.com>,
	Paul Moore <paul@...l-moore.com>,
	Stephen Smalley <sds@...ho.nsa.gov>,
	Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [RFC PATCH RESEND] vfs: Move security_inode_killpriv() after
 permission checks

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@...ei.org>

--
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/