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* [PATCH] extend IMA boot_aggregate with kernel measurements
@ 2020-06-11 19:54 Maurizio Drocco
  2020-06-12  0:29 ` Mimi Zohar
  0 siblings, 1 reply; 24+ messages in thread
From: Maurizio Drocco @ 2020-06-11 19:54 UTC (permalink / raw)
  To: linux-integrity
  Cc: jejb, Maurizio Drocco, Mimi Zohar, Dmitry Kasatkin, James Morris,
	Serge E. Hallyn, open list:SECURITY SUBSYSTEM, open list

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.

Signed-off-by: Maurizio Drocco <maurizio.drocco@ibm.com>
---
 security/integrity/ima/ima.h        |  2 +-
 security/integrity/ima/ima_crypto.c | 11 ++++++++++-
 2 files changed, 11 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..6f0137bdaf61 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -809,7 +809,7 @@ static void ima_pcrread(u32 idx, struct tpm_digest *d)
 static int ima_calc_boot_aggregate_tfm(char *digest, u16 alg_id,
 				       struct crypto_shash *tfm)
 {
-	struct tpm_digest d = { .alg_id = alg_id, .digest = {0} };
+	struct tpm_digest d = { .alg_id = alg_id, .digest = {0} }, d0 = d;
 	int rc;
 	u32 i;
 	SHASH_DESC_ON_STACK(shash, tfm);
@@ -830,6 +830,15 @@ static int ima_calc_boot_aggregate_tfm(char *digest, u16 alg_id,
 		rc = crypto_shash_update(shash, d.digest,
 					 crypto_shash_digestsize(tfm));
 	}
+	/* extend cumulative sha1 over tpm registers 8-9 */
+	for (i = TPM_PCR8; i < TPM_PCR10; i++) {
+		ima_pcrread(i, &d);
+		/* if not zero, accumulate with current aggregate */
+		if (memcmp(d.digest, d0.digest,
+					crypto_shash_digestsize(tfm) != 0))
+			rc = crypto_shash_update(shash, d.digest,
+					crypto_shash_digestsize(tfm));
+	}
 	if (!rc)
 		crypto_shash_final(shash, digest);
 	return rc;
-- 
2.17.1


^ permalink raw reply	[flat|nested] 24+ messages in thread
* [PATCH] ima_evm_utils: extended calc_bootaggr to PCRs 8 - 9
@ 2020-06-16 12:02 Maurizio Drocco
  2020-06-16 17:19 ` Mimi Zohar
  0 siblings, 1 reply; 24+ messages in thread
From: Maurizio Drocco @ 2020-06-16 12:02 UTC (permalink / raw)
  To: linux-integrity; +Cc: zohar, Maurizio

From: Maurizio <maurizio.drocco@ibm.com>

If PCRs 8 - 9 are set (i.e. not all-zeros), cal_bootaggr should include
them into the digest.

Signed-off-by: Maurizio Drocco <maurizio.drocco@ibm.com>
---
 src/evmctl.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/evmctl.c b/src/evmctl.c
index 1d065ce..701d643 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -1930,6 +1930,16 @@ static void calc_bootaggr(struct tpm_bank_info *bank)
 		}
 	}
 
+	for (i = 8; i < 10; i++) {
+		if (memcmp(bank->pcr[i], zero, bank->digest_size) != 0) {
+			err = EVP_DigestUpdate(pctx, bank->pcr[i], bank->digest_size);
+			if (!err) {
+				log_err("EVP_DigestUpdate() failed\n");
+				return;
+			}
+		}
+	}
+
 	err = EVP_DigestFinal(pctx, bank->digest, &mdlen);
 	if (!err) {
 		log_err("EVP_DigestFinal() failed\n");
@@ -1973,7 +1983,8 @@ static int append_bootaggr(char *bootaggr, struct tpm_bank_info *tpm_banks)
  * The IMA measurement list boot_aggregate is the link between the preboot
  * event log and the IMA measurement list.  Read and calculate all the
  * possible per TPM bank boot_aggregate digests based on the existing
- * PCRs 0 - 7 to validate against the IMA boot_aggregate record.
+ * PCRs 0 - 9 to validate against the IMA boot_aggregate record. If PCRs
+ * 8 - 9 are not set (i.e. all-zeros), only PCRs 0 - 7 are considered.
  */
 static int cmd_ima_bootaggr(struct command *cmd)
 {
-- 
2.17.1


^ permalink raw reply	[flat|nested] 24+ messages in thread

end of thread, back to index

Thread overview: 24+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
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
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
2020-06-16 12:02 [PATCH] " Maurizio Drocco
2020-06-16 17:19 ` Mimi Zohar

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