[PATCH ima-evm-utils] cmd_ima_bootaggr: Fix for systems without TPM 2.0

[Petr Vorel <pvorel@suse.cz>]

For both kernel with and without CONFIG_IMA=y.

NOTE: ima_boot_aggregate was added in dc00c92, without TPM 2.0
it just reported:
EVP_DigestInit() failed
(null):

Fixes: 917317a ("ima_evm_utils: emit the per TPM PCR bank
"boot_aggregate" values")

Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 src/evmctl.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/evmctl.c b/src/evmctl.c
index 1d065ce..94ec56b 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -1998,11 +1998,17 @@ static int cmd_ima_bootaggr(struct command *cmd)
 	 * Format: <hash algorithm name>:<boot_aggregate digest>\n ...
 	 */
 	for (i = 0; i < num_banks; i++) {
-		if (!tpm_banks[i].supported)
+		if (!tpm_banks[i].supported || !tpm_banks[i].algo_name)
 			continue;
 		bootaggr_len += strlen(tpm_banks[i].algo_name) + 1;
 		bootaggr_len += (tpm_banks[i].digest_size * 2) + 1;
 	}
+
+	if (!bootaggr_len) {
+		log_info("No TPM 2.0 PCR bank algorithm found (no TPM 2.0?)\n");
+		return -1;
+	}
+
 	bootaggr = malloc(bootaggr_len);
 
 	/*
@@ -2012,7 +2018,7 @@ static int cmd_ima_bootaggr(struct command *cmd)
 	 * strings.
 	 */
 	for (i = 0; i < num_banks; i++) {
-		if (!tpm_banks[i].supported)
+		if (!tpm_banks[i].supported || !tpm_banks[i].algo_name)
 			continue;
 		calc_bootaggr(&tpm_banks[i]);
 		offset += append_bootaggr(bootaggr + offset, tpm_banks + i);
-- 
2.27.0.rc0