[RFC PATCH 1/8] ima-evm-utils: treat unallocated banks as an error

From: Mimi Zohar <zohar@linux.ibm.com>
To: linux-integrity@vger.kernel.org
Cc: Roberto Sassu <roberto.sassu@huawei.com>,
	Vitaly Chikunov <vt@altlinux.org>,
	Patrick Uiterwijk <puiterwi@redhat.com>,
	Petr Vorel <pvorel@suse.cz>, Mimi Zohar <zohar@linux.ibm.com>
Subject: [RFC PATCH 1/8] ima-evm-utils: treat unallocated banks as an error
Date: Fri, 21 Feb 2020 13:38:51 -0500	[thread overview]
Message-ID: <1582310338-1562-2-git-send-email-zohar@linux.ibm.com> (raw)
In-Reply-To: <1582310338-1562-1-git-send-email-zohar@linux.ibm.com>

The TPM spec differentiates between an unknown bank and an unallocated
bank.  In terms of re-calculating the PCR, treat them as equivalent.

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
---
 src/evmctl.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/evmctl.c b/src/evmctl.c
index be59ead45189..704615694cec 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -1449,6 +1449,11 @@ static int tpm2_pcr_read(int idx, uint8_t *hwpcr, int len, char **errmsg)
 
 	/* get the popen "cmd" return code */
 	ret = pclose(fp);
+
+	/* Treat an unallocated bank as an error */
+	if (!ret && (strlen(pcr) < SHA_DIGEST_LENGTH))
+		ret = -1;
+
 	if (!ret)
 		hex2bin(hwpcr, pcr, SHA_DIGEST_LENGTH);
 	else
-- 
2.7.5

