linux-kernel - Re: [PATCH ghak46 V1] audit: normalize MAC

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Message-ID: <CAHC9VhQzt4-f5zYkh18NWcp0HALXNR3iB+jeGOPkxdZZx8SdLQ@mail.gmail.com>
Date:   Wed, 11 Apr 2018 17:08:34 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Richard Guy Briggs <rgb@...hat.com>
Cc:     Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        SElinux list <selinux@...ho.nsa.gov>,
        Linux Security Module list 
        <linux-security-module@...r.kernel.org>,
        Eric Paris <eparis@...hat.com>, Steve Grubb <sgrubb@...hat.com>
Subject: Re: [PATCH ghak46 V1] audit: normalize MAC_STATUS record

On Mon, Apr 9, 2018 at 7:34 PM, Richard Guy Briggs <rgb@...hat.com> wrote:
> There were two formats of the audit MAC_STATUS record, one of which was more
> standard than the other.  One listed enforcing status changes and the
> other listed enabled status changes with a non-standard label.  In
> addition, the record was missing information about which LSM was
> responsible and the operation's completion status.  While this record is
> only issued on success, the parser expects the res= field to be present.
>
> old enforcing/permissive:
> type=MAC_STATUS msg=audit(1523312831.378:24514): enforcing=0 old_enforcing=1 auid=0 ses=1
> old enable/disable:
> type=MAC_STATUS msg=audit(1523312831.378:24514): selinux=0 auid=0 ses=1
>
> List both sets of status and old values and add the lsm= field and the
> res= field.
>
> Here is the new format:
> type=MAC_STATUS msg=audit(1523293828.657:891): enforcing=0 old_enforcing=1 auid=0 ses=1 enabled=1 old-enabled=1 lsm=selinux res=1
>
> This record already accompanied a SYSCALL record.
>
> See: https://github.com/linux-audit/audit-kernel/issues/46
> Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> ---
>  security/selinux/selinuxfs.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
> index 00eed84..00b21b2 100644
> --- a/security/selinux/selinuxfs.c
> +++ b/security/selinux/selinuxfs.c
> @@ -145,10 +145,11 @@ static ssize_t sel_write_enforce(struct file *file, const char __user *buf,
>                 if (length)
>                         goto out;
>                 audit_log(current->audit_context, GFP_KERNEL, AUDIT_MAC_STATUS,
> -                       "enforcing=%d old_enforcing=%d auid=%u ses=%u",
> +                       "enforcing=%d old_enforcing=%d auid=%u ses=%u"
> +                       " enabled=%d old-enabled=%d lsm=selinux res=1",
>                         new_value, selinux_enforcing,
>                         from_kuid(&init_user_ns, audit_get_loginuid(current)),
> -                       audit_get_sessionid(current));
> +                       audit_get_sessionid(current), selinux_enabled, selinux_enabled);

This looks fine.

>                 selinux_enforcing = new_value;
>                 if (selinux_enforcing)
>                         avc_ss_reset(0);
> @@ -272,9 +273,11 @@ static ssize_t sel_write_disable(struct file *file, const char __user *buf,
>                 if (length)
>                         goto out;
>                 audit_log(current->audit_context, GFP_KERNEL, AUDIT_MAC_STATUS,
> -                       "selinux=0 auid=%u ses=%u",
> +                       "enforcing=%d old_enforcing=%d auid=%u ses=%u"
> +                       " enabled=%d old-enabled=%d lsm=selinux res=1",
> +                       selinux_enforcing, selinux_enforcing,
>                         from_kuid(&init_user_ns, audit_get_loginuid(current)),
> -                       audit_get_sessionid(current));
> +                       audit_get_sessionid(current), 0, 1);

It needs to be said again that I'm opposed to changes like this:
inserting new fields, removing fields, or otherwise changing the
format in ways that aren't strictly the addition of new fields to the
end of a record is a Bad Thing.  However, there are exceptions (there
are *always* exceptions), and this seems like a reasonable change that
shouldn't negatively affect anyone.

I'll merge this once the merge window comes to a close (we are going
to need to base selinux/next on v4.17-rc1).

>         }
>
>         length = count;
> --
> 1.8.3.1
>

-- 
paul moore
www.paul-moore.com