linux-kernel - Re: [PATCH v4 3/5] security: Allow all LSMs to provide xattrs for inode_init

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: <6b4d47765a4ddcfdf07158f3ad0737fa3aa5823e.camel@linux.ibm.com>
Date:   Thu, 17 Nov 2022 12:24:54 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Casey Schaufler <casey@...aufler-ca.com>,
        Roberto Sassu <roberto.sassu@...weicloud.com>,
        dmitry.kasatkin@...il.com, paul@...l-moore.com, jmorris@...ei.org,
        serge@...lyn.com, stephen.smalley.work@...il.com,
        eparis@...isplace.org
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, selinux@...r.kernel.org,
        reiserfs-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
        keescook@...omium.org, nicolas.bouchinet@...p-os.org,
        Roberto Sassu <roberto.sassu@...wei.com>
Subject: Re: [PATCH v4 3/5] security: Allow all LSMs to provide xattrs for
 inode_init_security hook

On Thu, 2022-11-17 at 09:18 -0800, Casey Schaufler wrote:
> On 11/17/2022 8:05 AM, Mimi Zohar wrote:
> > hOn Thu, 2022-11-10 at 10:46 +0100, Roberto Sassu wrote:
> >> From: Roberto Sassu <roberto.sassu@...wei.com>
> >>
> >> Currently, security_inode_init_security() supports only one LSM providing
> >> an xattr and EVM calculating the HMAC on that xattr, plus other inode
> >> metadata.
> >>
> >> Allow all LSMs to provide one or multiple xattrs, by extending the security
> >> blob reservation mechanism. Introduce the new lbs_xattr field of the
> >> lsm_blob_sizes structure, so that each LSM can specify how many xattrs it
> >> needs, and the LSM infrastructure knows how many xattr slots it should
> >> allocate.
> > Perhaps supporting per LSM multiple xattrs is a nice idea, but EVM
> > doesn't currently support it.  The LSM xattrs are hard coded in
> > evm_config_default_xattrnames[],  based on whether the LSM is
> > configured.  Additional security xattrs may be included in the
> > security.evm calculation, by extending the list via
> > security/integrity/evm/evm_xattrs.
> 
> Smack uses multiple xattrs. All file system objects have a SMACK64
> attribute, which is used for access control. A program file may have
> a SMACK64EXEC attribute, which is the label the program will run with.
> A library may have a SMACK64MMAP attribute to restrict loading. A
> directory may have a SMACK64TRANSMUTE attribute, which modifies the
> new object creation behavior.
> 
> The point being that it may be more than a "nice idea" to support
> multiple xattrs. It's not a hypothetical situation.

And each of these addiitonal Smack xattrs are already defined in 
evm_config_default_xattrnames[].

Mimi