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Date:   Mon, 20 Jul 2020 12:38:41 -0300
From:   Bruno Meneguele <bmeneg@redhat.com>
To:     Mimi Zohar <zohar@linux.ibm.com>
Cc:     Nayna <nayna@linux.vnet.ibm.com>, linux-kernel@vger.kernel.org,
        x86@kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-s390@vger.kernel.org, linux-integrity@vger.kernel.org,
        erichte@linux.ibm.com, nayna@linux.ibm.com, stable@vger.kernel.org
Subject: Re: [PATCH v6] ima: move APPRAISE_BOOTPARAM dependency on
 ARCH_POLICY to runtime
Message-ID: <20200720153841.GG10323@glitch>
References: <20200713164830.101165-1-bmeneg@redhat.com>
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On Mon, Jul 20, 2020 at 10:56:55AM -0400, Mimi Zohar wrote:
> On Mon, 2020-07-20 at 10:40 -0400, Nayna wrote:
> > On 7/13/20 12:48 PM, Bruno Meneguele wrote:
> > > The IMA_APPRAISE_BOOTPARAM config allows enabling different "ima_appr=
aise=3D"
> > > modes - log, fix, enforce - at run time, but not when IMA architectur=
e
> > > specific policies are enabled. =A0This prevents properly labeling the
> > > filesystem on systems where secure boot is supported, but not enabled=
 on the
> > > platform. =A0Only when secure boot is actually enabled should these I=
MA
> > > appraise modes be disabled.
> > >
> > > This patch removes the compile time dependency and makes it a runtime
> > > decision, based on the secure boot state of that platform.
> > >
> > > Test results as follows:
> > >
> > > -> x86-64 with secure boot enabled
> > >
> > > [    0.015637] Kernel command line: <...> ima_policy=3Dappraise_tcb i=
ma_appraise=3Dfix
> > > [    0.015668] ima: Secure boot enabled: ignoring ima_appraise=3Dfix =
boot parameter option
> > >
>=20
> Is it common to have two colons in the same line? =A0Is the colon being
> used as a delimiter when parsing the kernel logs? =A0Should the second
> colon be replaced with a hyphen? =A0(No need to repost. =A0I'll fix it
> up.)
> =A0

AFAICS it has been used without any limitations, e.g:

PM: hibernation: Registered nosave memory: [mem 0x00000000-0x00000fff]
clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 13=
3484873504 ns
microcode: CPU0: patch_level=3D0x08701013
Lockdown: modprobe: unsigned module loading is restricted; see man kernel_l=
ockdown.7
...

I'd say we're fine using it.

>=20
> > > -> powerpc with secure boot disabled
> > >
> > > [    0.000000] Kernel command line: <...> ima_policy=3Dappraise_tcb i=
ma_appraise=3Dfix
> > > [    0.000000] Secure boot mode disabled
> > >
> > > -> Running the system without secure boot and with both options set:
> > >
> > > CONFIG_IMA_APPRAISE_BOOTPARAM=3Dy
> > > CONFIG_IMA_ARCH_POLICY=3Dy
> > >
> > > Audit prompts "missing-hash" but still allow execution and, consequen=
tly,
> > > filesystem labeling:
> > >
> > > type=3DINTEGRITY_DATA msg=3Daudit(07/09/2020 12:30:27.778:1691) : pid=
=3D4976
> > > uid=3Droot auid=3Droot ses=3D2
> > > subj=3Dunconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 op=3Dapp=
raise_data
> > > cause=3Dmissing-hash comm=3Dbash name=3D/usr/bin/evmctl dev=3D"dm-0" =
ino=3D493150
> > > res=3Dno
> > >
> > > Cc: stable@vger.kernel.org
> > > Fixes: d958083a8f64 ("x86/ima: define arch_get_ima_policy() for x86")
> > > Signed-off-by: Bruno Meneguele <bmeneg@redhat.com>
> >=20
> >=20
> > Reviewed-by: Nayna Jain<nayna@linux.ibm.com>
> > Tested-by: Nayna Jain<nayna@linux.ibm.com>
>=20
> Thanks, Nayna.
>=20
> Mimi
>=20

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