From: Bruno Meneguele <bmeneg@redhat.com>
To: Maurizio Drocco <maurizio.drocco@ibm.com>
Cc: zohar@linux.ibm.com, 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 v4] ima: extend boot_aggregate with kernel measurements
Date: Tue, 23 Jun 2020 15:53:00 -0300 [thread overview]
Message-ID: <20200623185300.GD4983@glitch> (raw)
In-Reply-To: <20200623155732.105-1-maurizio.drocco@ibm.com>
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On Tue, Jun 23, 2020 at 11:57:32AM -0400, Maurizio Drocco wrote:
> 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. Registers 8-9 should be
> only included in non-SHA1 digests to avoid ambiguity.
>
> Signed-off-by: Maurizio Drocco <maurizio.drocco@ibm.com>
> ---
> Changelog:
> v4:
> - Reworded comments: PCRs 8 & 9 are always included in non-sha1 digests
> v3:
> - Limit including PCRs 8 & 9 to non-sha1 hashes
> v2:
> - Minor comment improvements
> 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..011c3c76af86 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 */
> 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.
> + */
> + 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;
> --
> 2.17.1
>
Reviewed-by: Bruno Meneguele <bmeneg@redhat.com>
I've tested this patch with both TPM 1.2 and TPM 2.0 + ima-evm-utils
support patch. Everything seems fine.
Thanks.
--
bmeneg
PGP Key: http://bmeneg.com/pubkey.txt
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next prev parent reply other threads:[~2020-06-23 18:53 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 19:54 [PATCH] extend IMA boot_aggregate with kernel measurements 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
2020-06-23 15:57 ` [PATCH v4] " Maurizio Drocco
2020-06-23 18:53 ` Bruno Meneguele [this message]
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
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