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From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Mimi Zohar <zohar@linux.ibm.com>,
	linuxppc-dev@ozlabs.org, linux-efi@vger.kernel.org,
	linux-integrity@vger.kernel.org
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Eric Ricther <erichte@linux.ibm.com>,
	Nayna Jain <nayna@linux.ibm.com>,
	linux-kernel@vger.kernel.org, Mimi Zohar <zohar@linux.ibm.com>,
	David Howells <dhowells@redhat.com>,
	Paul Mackerras <paulus@samba.org>, Jeremy Kerr <jk@ozlabs.org>,
	Jessica Yu <jeyu@kernel.org>,
	Oliver O'Halloran <oohall@gmail.com>
Subject: Re: [PATCH v10 7/9] ima: check against blacklisted hashes for files with modsig
Date: Thu, 14 Nov 2019 20:08:11 +1100 (AEDT)	[thread overview]
Message-ID: <47DFy33C6Yz9sSP@ozlabs.org> (raw)
In-Reply-To: <1572492694-6520-8-git-send-email-zohar@linux.ibm.com>

On Thu, 2019-10-31 at 03:31:32 UTC, Mimi Zohar wrote:
> From: Nayna Jain <nayna@linux.ibm.com>
> 
> Asymmetric private keys are used to sign multiple files.  The kernel
> currently supports checking against blacklisted keys.  However, if the
> public key is blacklisted, any file signed by the blacklisted key will
> automatically fail signature verification.  Blacklisting the public
> key is not fine enough granularity, as we might want to only blacklist
> a particular file.
> 
> This patch adds support for checking against the blacklisted hash of
> the file, without the appended signature, based on the IMA policy.  It
> defines a new policy option "appraise_flag=check_blacklist".
> 
> In addition to the blacklisted binary hashes stored in the firmware "dbx"
> variable, the Linux kernel may be configured to load blacklisted binary
> hashes onto the .blacklist keyring as well.  The following example shows
> how to blacklist a specific kernel module hash.
> 
> $ sha256sum kernel/kheaders.ko
> 77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3
> kernel/kheaders.ko
> 
> $ grep BLACKLIST .config
> CONFIG_SYSTEM_BLACKLIST_KEYRING=y
> CONFIG_SYSTEM_BLACKLIST_HASH_LIST="blacklist-hash-list"
> 
> $ cat certs/blacklist-hash-list
> "bin:77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3"
> 
> Update the IMA custom measurement and appraisal policy rules
> (/etc/ima-policy):
> 
> measure func=MODULE_CHECK template=ima-modsig
> appraise func=MODULE_CHECK appraise_flag=check_blacklist
> appraise_type=imasig|modsig
> 
> After building, installing, and rebooting the kernel:
> 
>  545660333 ---lswrv      0     0   \_ blacklist:
> bin:77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3
> 
> measure func=MODULE_CHECK template=ima-modsig
> appraise func=MODULE_CHECK appraise_flag=check_blacklist
> appraise_type=imasig|modsig
> 
> modprobe: ERROR: could not insert 'kheaders': Permission denied
> 
> 10 0c9834db5a0182c1fb0cdc5d3adcf11a11fd83dd ima-sig
> sha256:3bc6ed4f0b4d6e31bc1dbc9ef844605abc7afdc6d81a57d77a1ec9407997c40
> 2 /usr/lib/modules/5.4.0-rc3+/kernel/kernel/kheaders.ko
> 
> 10 82aad2bcc3fa8ed94762356b5c14838f3bcfa6a0 ima-modsig
> sha256:3bc6ed4f0b4d6e31bc1dbc9ef844605abc7afdc6d81a57d77a1ec9407997c40
> 2 /usr/lib/modules/5.4.0rc3+/kernel/kernel/kheaders.ko  sha256:77fa889b3
> 5a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3
> 3082029a06092a864886f70d010702a082028b30820287020101310d300b0609608648
> 016503040201300b06092a864886f70d01070131820264....
> 
> 10 25b72217cc1152b44b134ce2cd68f12dfb71acb3 ima-buf
> sha256:8b58427fedcf8f4b20bc8dc007f2e232bf7285d7b93a66476321f9c2a3aa132
> b blacklisted-hash
> 77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3
> 
> Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
> Cc: Jessica Yu <jeyu@kernel.org>
> Cc: David Howells <dhowells@redhat.com>
> [zohar@linux.ibm.com: updated patch description]
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/273df864cf7466fb170b8dcc1abd672cd08ad8d3

cheers

  reply	other threads:[~2019-11-14 10:07 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-31  3:31 [PATCH v10 0/9] powerpc: Enabling IMA arch specific secure boot policies Mimi Zohar
2019-10-31  3:31 ` [PATCH v10 1/9] powerpc: detect the secure boot mode of the system Mimi Zohar
2019-11-05  5:14   ` Eric Richter
2019-11-05 23:00   ` [PATCH v10a " Eric Richter
2019-11-14  9:08     ` Michael Ellerman
2019-10-31  3:31 ` [PATCH v10 2/9] powerpc/ima: add support to initialize ima policy rules Mimi Zohar
2019-11-14  9:08   ` Michael Ellerman
2019-10-31  3:31 ` [PATCH v10 3/9] powerpc: detect the trusted boot state of the system Mimi Zohar
2019-11-05 23:02   ` [PATCH v10a " Eric Richter
2019-11-14  9:08     ` Michael Ellerman
2019-10-31  3:31 ` [PATCH v10 4/9] powerpc/ima: define trusted boot policy Mimi Zohar
2019-11-14  9:08   ` Michael Ellerman
2019-10-31  3:31 ` [PATCH v10 5/9] ima: make process_buffer_measurement() generic Mimi Zohar
2019-10-31 17:02   ` Lakshmi Ramasubramanian
2019-10-31 17:22     ` Lakshmi Ramasubramanian
2019-11-14  9:08   ` Michael Ellerman
2019-10-31  3:31 ` [PATCH v10 6/9] certs: add wrapper function to check blacklisted binary hash Mimi Zohar
2019-11-14  9:08   ` Michael Ellerman
2019-10-31  3:31 ` [PATCH v10 7/9] ima: check against blacklisted hashes for files with modsig Mimi Zohar
2019-11-14  9:08   ` Michael Ellerman [this message]
2019-10-31  3:31 ` [PATCH v10 8/9] powerpc/ima: update ima arch policy to check for blacklist Mimi Zohar
2019-11-14  9:08   ` Michael Ellerman
2019-10-31  3:31 ` [RFC PATCH v10 9/9] powerpc/ima: indicate kernel modules appended signatures are enforced Mimi Zohar
2019-11-14  9:08   ` Michael Ellerman
2019-12-09 20:27 ` [PATCH v10 0/9] powerpc: Enabling IMA arch specific secure boot policies Lakshmi Ramasubramanian
2019-12-09 21:36   ` Mimi Zohar

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