Linux-Integrity Archive on lore.kernel.org
 help / color / Atom feed
From: Mimi Zohar <zohar@linux.ibm.com>
To: Maurizio Drocco <maurizio.drocco@ibm.com>
Cc: Silviu.Vlasceanu@huawei.com, dmitry.kasatkin@gmail.com,
	jejb@linux.ibm.com, jmorris@namei.org,
	linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	mdrocco@linux.vnet.ibm.com, roberto.sassu@huawei.com,
	serge@hallyn.com
Subject: Re: [PATCH] ima: extend boot_aggregate with kernel measurements
Date: Tue, 23 Jun 2020 10:03:10 -0400
Message-ID: <1592920990.5437.15.camel@linux.ibm.com> (raw)
In-Reply-To: <20200622045019.1636-1-maurizio.drocco@ibm.com>

Hi Maurizio,

When re-posting patches, please include the version number (e.g.
[PATCH v4] ima: ... ).

On Mon, 2020-06-22 at 00:50 -0400, Maurizio Drocco wrote:
> IMA is not considering TPM registers 8-9 when calculating the boot
> aggregate.

This line is unnecessary with the following change.

> When registers 8-9 are used to store measurements of the
> kernel and its command line (e.g., grub2 bootloader with tpm module
> enabled), IMA should include them in the boot aggregate.

The "When" clause makes this sound like PCRs 8 & 9 are not always
included.  I would split this into two sentences.

>  Registers
> 8-9 are only included in non-SHA1 boot_aggregate digests to avoid
> ambiguity.
> 
> Signed-off-by: Maurizio Drocco <maurizio.drocco@ibm.com>
> ---

Missing "Changelog:".

Changelog:
v2: 
- Limit including PCRs 8 & 9 to non-sha1 hashes
v1:
- Include non zero PCRs 8 & 9 in the boot_aggregate

>  security/integrity/ima/ima.h        |  2 +-
>  security/integrity/ima/ima_crypto.c | 15 ++++++++++++++-
>  2 files changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index df93ac258e01..9d94080bdad8 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -30,7 +30,7 @@
>  
>  enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_BINARY_NO_FIELD_LEN,
>  		     IMA_SHOW_BINARY_OLD_STRING_FMT, IMA_SHOW_ASCII };
> -enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 };
> +enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8, TPM_PCR10 = 10 };
>  
>  /* digest size for IMA, fits SHA1 or MD5 */
>  #define IMA_DIGEST_SIZE		SHA1_DIGEST_SIZE
> diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
> index 220b14920c37..d02917d85033 100644
> --- a/security/integrity/ima/ima_crypto.c
> +++ b/security/integrity/ima/ima_crypto.c
> @@ -823,13 +823,26 @@ static int ima_calc_boot_aggregate_tfm(char *digest, u16 alg_id,
>  	if (rc != 0)
>  		return rc;
>  
> -	/* cumulative sha1 over tpm registers 0-7 */
> +	/* cumulative digest over tpm registers 0-7 */

Please uppercase "tpm" here and below.

>  	for (i = TPM_PCR0; i < TPM_PCR8; i++) {
>  		ima_pcrread(i, &d);
>  		/* now accumulate with current aggregate */
>  		rc = crypto_shash_update(shash, d.digest,
>  					 crypto_shash_digestsize(tfm));
>  	}
> +	/*
> +	 * extend cumulative digest over tpm registers 8-9, which contain
> +	 * measurement for the kernel command line (reg. 8) and image (reg. 9)
> +	 * in a typical PCR allocation. Registers 8-9 are only included in
> +	 * non-SHA1 boot_aggregate digests to avoid ambiguity.
> +	 */

Comments that are full sentences should start with an uppercase letter
and end with a period (e.g. Extend).

thanks,

Mimi

> +	if (alg_id != TPM_ALG_SHA1) {
> +		for (i = TPM_PCR8; i < TPM_PCR10; i++) {
> +			ima_pcrread(i, &d);
> +			rc = crypto_shash_update(shash, d.digest,
> +						crypto_shash_digestsize(tfm));
> +		}
> +	}
>  	if (!rc)
>  		crypto_shash_final(shash, digest);
>  	return rc;


  reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-11 19:54 [PATCH] extend IMA " Maurizio Drocco
2020-06-12  0:29 ` Mimi Zohar
2020-06-12 14:38   ` Maurizio Drocco
2020-06-12 15:11     ` Roberto Sassu
2020-06-12 17:14       ` James Bottomley
2020-06-16 17:29         ` Roberto Sassu
2020-06-16 18:11           ` Mimi Zohar
2020-06-18 12:38             ` Roberto Sassu
2020-06-18 20:11               ` Maurizio Drocco
2020-06-18 20:11                 ` [PATCH] ima_evm_utils: extended calc_bootaggr to PCRs 8 - 9 Maurizio Drocco
2020-06-22 20:14                   ` Mimi Zohar
2020-06-22  4:50                     ` [PATCH] ima: extend boot_aggregate with kernel measurements Maurizio Drocco
2020-06-23 14:03                       ` Mimi Zohar [this message]
2020-06-23 15:57                         ` [PATCH v4] " Maurizio Drocco
2020-06-23 18:53                           ` Bruno Meneguele
2020-06-23 18:01                     ` [PATCH v2] ima_evm_utils: extended calc_bootaggr to PCRs 8 - 9 Maurizio Drocco
2020-06-23 18:13                       ` Bruno Meneguele
2020-06-24 21:17                         ` Stefan Berger
2020-06-24 21:33                           ` [PATCH] " Maurizio Drocco
2020-06-24 21:33                           ` [PATCH v2] " Bruno Meneguele
2020-06-24 21:35                             ` [PATCH v3] " Maurizio Drocco
2020-06-24 21:50                               ` Bruno Meneguele

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1592920990.5437.15.camel@linux.ibm.com \
    --to=zohar@linux.ibm.com \
    --cc=Silviu.Vlasceanu@huawei.com \
    --cc=dmitry.kasatkin@gmail.com \
    --cc=jejb@linux.ibm.com \
    --cc=jmorris@namei.org \
    --cc=linux-integrity@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=maurizio.drocco@ibm.com \
    --cc=mdrocco@linux.vnet.ibm.com \
    --cc=roberto.sassu@huawei.com \
    --cc=serge@hallyn.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Integrity Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-integrity/0 linux-integrity/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-integrity linux-integrity/ https://lore.kernel.org/linux-integrity \
		linux-integrity@vger.kernel.org
	public-inbox-index linux-integrity

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-integrity


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git