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From: Maurizio Drocco <maurizio.drocco@ibm.com>
To: zohar@linux.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, maurizio.drocco@ibm.com,
	mdrocco@linux.vnet.ibm.com, roberto.sassu@huawei.com,
	serge@hallyn.com
Subject: [PATCH] ima: extend boot_aggregate with kernel measurements
Date: Mon, 22 Jun 2020 00:50:19 -0400
Message-ID: <20200622045019.1636-1-maurizio.drocco@ibm.com> (raw)
In-Reply-To: <1592856871.4987.21.camel@linux.ibm.com>

IMA is not considering TPM registers 8-9 when calculating the boot
aggregate. 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. Registers
8-9 are only included in non-SHA1 boot_aggregate digests to avoid
ambiguity.

Signed-off-by: Maurizio Drocco <maurizio.drocco@ibm.com>
---
 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 */
 	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


  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                     ` Maurizio Drocco [this message]
2020-06-23 14:03                       ` [PATCH] ima: extend boot_aggregate with kernel measurements Mimi Zohar
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

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