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From:   rishi gupta <gupt21@gmail.com>
Date:   Mon, 9 Nov 2020 21:14:14 +0530
Message-ID: <CALUj-gtQsSnU0Yq5Syc7aOkN0PH_MHvziuuG1-9zotVUAJ2QoQ@mail.gmail.com>
Subject: Re: Selinux policy for x509_ima.der public certificate loaded by
 kernel during boot
To:     Mikhail Novosyolov <m.novosyolov@rosalinux.ru>
Cc:     linux-integrity <linux-integrity@vger.kernel.org>,
        selinux-refpolicy@vger.kernel.org, selinux@vger.kernel.org
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On Sat, Nov 7, 2020 at 3:45 AM Mikhail Novosyolov
<m.novosyolov@rosalinux.ru> wrote:
>
>
> 06.11.2020 18:50, rishi gupta =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> > On Fri, Nov 6, 2020 at 8:42 PM Mikhail Novosyolov
> > <m.novosyolov@rosalinux.ru> wrote:
> >> 06.11.2020 15:22, rishi gupta =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> >>> I am getting below error as selinux is denying access to the .ima
> >>> keyring. Looking for guidance for asymmetric public key selinux
> >>> policy.
> >>>
> >>> [  172.014855] integrity: Request for unknown key 'id:87deb3bf' err -=
13
> >> I am getting the same error without selinux.
> > If I make selinux permissive, it works for me. So I know in my case
> > the problem is selinux.
> >>> [  172.015035] audit: type=3D1800 audit(1604596570.579:240): pid=3D82=
5
> >>> uid=3D1021 auid=3D4294967295 ses=3D4294967295
> >>> subj=3Dsystem_u:system_r:mydaemon_t:s0-s15:c0.c1023 op=3D"appraise_da=
ta"
> >>> cause=3D"invalid-signature" comm=3D"mydaemon"
> >>> name=3D"/usr/lib/libstdc++.so.6.0.25" dev=3D"ubifs" ino=3D14353 res=
=3D0
> >> Selinux context is just logged here. It has nothing to do with reasons=
 of ivalid signature. Public key seems to be not loaded.
> > Basically when we access a file, driver checks if selinux allow access
> > to it or not. In my case this function is returning -EACCES
> > https://github.com/torvalds/linux/blob/master/security/keys/permission.=
c#L88
> >>> (a) Do I need to set the selinux context of file
> >>> /etc/keys/x509_ima.der. If yes what it should be.
> >>> (b) Do I need to set some selinux rule for .ima keyring. If yes how. =
I
> >>> tried a lot but could not find any resource.
> >> Usually IMA policy is loaded before SELinux policy I think
> > I am using the policy defined in ima_policy driver as of now. My kernel=
 is 4.14.
> What is "ima_policy driver"? How does selinux and IMA policies get loaded=
 on your system?

For test purpose I am using "ima_policy=3Dtcb ima_appraise_tcb" in the
commandline.
I have not changed anything in the policy defined in 4.14 kernel driver for=
 now.
https://github.com/torvalds/linux/blob/bebc6082da0a9f5d47a1ea2edc099bf67105=
8bd4/security/integrity/ima/ima_policy.c#L132
https://github.com/torvalds/linux/blob/bebc6082da0a9f5d47a1ea2edc099bf67105=
8bd4/security/integrity/ima/ima_policy.c#L88

> >>> Regards,
> >>> Rishi