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From: Roberto Sassu <roberto.sassu@huawei.com>
To: Mimi Zohar <zohar@linux.ibm.com>,
	"James.Bottomley@HansenPartnership.com" 
	<James.Bottomley@HansenPartnership.com>,
	"jarkko.sakkinen@linux.intel.com"
	<jarkko.sakkinen@linux.intel.com>
Cc: "linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Silviu Vlasceanu <Silviu.Vlasceanu@huawei.com>
Subject: RE: [PATCH v2 5/8] ima: Switch to dynamically allocated buffer for template digests
Date: Thu, 6 Feb 2020 16:36:28 +0000
Message-ID: <5bbf950910db4a5a853aaaeba5b18529@huawei.com> (raw)
In-Reply-To: <1581006834.5585.430.camel@linux.ibm.com>

> -----Original Message-----
> From: owner-linux-security-module@vger.kernel.org [mailto:owner-linux-
> security-module@vger.kernel.org] On Behalf Of Mimi Zohar
> Sent: Thursday, February 6, 2020 5:34 PM
> To: Roberto Sassu <roberto.sassu@huawei.com>;
> James.Bottomley@HansenPartnership.com;
> jarkko.sakkinen@linux.intel.com
> Cc: linux-integrity@vger.kernel.org; linux-security-module@vger.kernel.org;
> linux-kernel@vger.kernel.org; Silviu Vlasceanu
> <Silviu.Vlasceanu@huawei.com>
> Subject: Re: [PATCH v2 5/8] ima: Switch to dynamically allocated buffer for
> template digests
> 
> On Thu, 2020-02-06 at 16:27 +0000, Roberto Sassu wrote:
> > > -----Original Message-----
> > > From: Mimi Zohar [mailto:zohar@linux.ibm.com]
> > > Sent: Thursday, February 6, 2020 5:08 PM
> > > To: Roberto Sassu <roberto.sassu@huawei.com>;
> > > James.Bottomley@HansenPartnership.com;
> > > jarkko.sakkinen@linux.intel.com
> > > Cc: linux-integrity@vger.kernel.org; linux-security-
> module@vger.kernel.org;
> > > linux-kernel@vger.kernel.org; Silviu Vlasceanu
> > > <Silviu.Vlasceanu@huawei.com>
> > > Subject: Re: [PATCH v2 5/8] ima: Switch to dynamically allocated buffer
> for
> > > template digests
> > >
> > > Hi Roberto,
> > >
> > > On Wed, 2020-02-05 at 11:33 +0100, Roberto Sassu wrote:
> > > > This patch dynamically allocates the array of tpm_digest structures in
> > > > ima_alloc_init_template() and ima_restore_template_data(). The size
> of
> > > the
> > > > array, stored in ima_num_template_digests, is initially equal to 1
> (SHA1)
> > > > and will be determined in the upcoming patches depending on the
> > > allocated
> > > > PCR banks and the chosen default IMA algorithm.
> > > >
> > > > Calculating the SHA1 digest is mandatory, as SHA1 still remains the
> default
> > > > hash algorithm for the measurement list. When IMA will support the
> > > Crypto
> > > > Agile format, remaining digests will be also provided.
> > > >
> > > > The position in the array of the SHA1 digest is stored in the
> ima_sha1_idx
> > > > global variable and it is determined at IMA initialization time.
> > > >
> > > > Changelog
> > > >
> > > > v1:
> > > > - move ima_sha1_idx to ima_crypto.c
> > > > - introduce ima_num_template_digests (suggested by Mimi)
> > >
> > > Instead of hardcoding "nr_allocated_banks + 1" or nr_allocated_banks +
> > > 2", I suggested defining "nr_allocated_banks + extra", where "extra"
> > > could be 0, 1, or 2.
> > >
> > > The rest of the code would remain exactly the same as you had.
> >
> > Ok. I did a small improvement. Since we determine the number of
> > required elements of ima_algo_array before kmalloc() I thought it
> > was ok to directly set that number of elements in a single variable.
> >
> > If you think that having two variables is better, I will change it.
> 
> The connection to nr_allocated_banks is then not as visible.  Using
> two variables is clearer.

Ok, no problem. I will change it in the next version.

Roberto

HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Li Peng, Li Jian, Shi Yanli

  reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05 10:33 [PATCH v2 0/8] ima: support stronger algorithms for attestation Roberto Sassu
2020-02-05 10:33 ` [PATCH v2 1/8] tpm: Initialize crypto_id of allocated_banks to HASH_ALGO__LAST Roberto Sassu
2020-02-05 21:57   ` Jarkko Sakkinen
2020-02-05 10:33 ` [PATCH v2 2/8] ima: Switch to ima_hash_algo for boot aggregate Roberto Sassu
     [not found]   ` <20200205144515.1DDE4217F4@mail.kernel.org>
2020-02-05 15:36     ` Roberto Sassu
2020-02-05 20:41   ` Mimi Zohar
2020-02-06  9:33     ` Roberto Sassu
2020-02-05 21:00   ` Mimi Zohar
2020-02-06  9:36     ` Roberto Sassu
2020-02-06 12:17       ` Mimi Zohar
2020-02-06 12:28         ` Roberto Sassu
2020-02-06 12:31           ` Mimi Zohar
2020-02-05 10:33 ` [PATCH v2 3/8] ima: Evaluate error in init_ima() Roberto Sassu
2020-02-05 10:39   ` Roberto Sassu
2020-02-05 10:33 ` [PATCH v2 4/8] ima: Store template digest directly in ima_template_entry Roberto Sassu
2020-02-05 10:33 ` [PATCH v2 5/8] ima: Switch to dynamically allocated buffer for template digests Roberto Sassu
2020-02-05 16:39   ` Roberto Sassu
2020-02-06 16:08   ` Mimi Zohar
2020-02-06 16:27     ` Roberto Sassu
2020-02-06 16:33       ` Mimi Zohar
2020-02-06 16:36         ` Roberto Sassu [this message]
2020-02-05 10:33 ` [PATCH v2 6/8] ima: Allocate and initialize tfm for each PCR bank Roberto Sassu
2020-02-05 23:41   ` kbuild test robot
2020-02-05 23:41   ` [RFC PATCH] ima: ima_init_ima_crypto() can be static kbuild test robot
2020-02-05 10:33 ` [PATCH v2 7/8] ima: Calculate and extend PCR with digests in ima_template_entry Roberto Sassu
2020-02-05 10:33 ` [PATCH v2 8/8] ima: Use ima_hash_algo for collision detection in the measurement list Roberto Sassu
     [not found]   ` <20200302012218.GU6548@shao2-debian>
2020-03-02  9:46     ` [ima] 9165b814d2: BUG:kernel_NULL_pointer_dereference,address Roberto Sassu

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