[2/6] ima-evm-utils: Change PCR iterater from int to uint32_t

Commit Message

Ken Goldman Oct. 5, 2020, 10:27 p.m. UTC

PCR numbers are naturally unsigned values.  Further, they are
32 bits, even on 64-bit machines. This change eliminates the
need for negative value and overflow tests.

The parameter name is changed from j and idx to pcrHandle,
which is more descriptive and is the parameter name used in
the TPM 2.0 specification.

Signed-off-by: Ken Goldman <[e-mail]>
---
  src/evmctl.c         | 9 +++++----
  src/pcr.h            | 2 +-
  src/pcr_tss.c        | 4 ++--
  src/pcr_tsspcrread.c | 4 ++--
  4 files changed, 10 insertions(+), 9 deletions(-)

Patch

diff --git a/src/evmctl.c b/src/evmctl.c
index 1815f55..b056a1e 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -1895,7 +1895,8 @@  static int read_tpm_banks(int num_banks, struct tpm_bank_info *bank)
  {
  	int tpm_enabled = 0;
  	char *errmsg = NULL;
-	int i, j;
+	int i;
+	uint32_t pcrHandle;
  	int err;

  	/* If --pcrs was specified, read only from the specified file(s) */
@@ -1915,9 +1916,9 @@  static int read_tpm_banks(int num_banks, struct tpm_bank_info *bank)
  	/* Read PCRs from multiple TPM 2.0 banks */
  	for (i = 0; i < num_banks; i++) {
  		err = 0;
-		for (j = 0; j < NUM_PCRS && !err; j++) {
-			err = tpm2_pcr_read(bank[i].algo_name, j,
-					    bank[i].pcr[j], bank[i].digest_size,
+		for (pcrHandle = 0; pcrHandle < NUM_PCRS && !err; pcrHandle++) {
+			err = tpm2_pcr_read(bank[i].algo_name, pcrHandle,
+					    bank[i].pcr[pcrHandle], bank[i].digest_size,
  					    &errmsg);
  			if (err) {
  				log_debug("Failed to read %s PCRs: (%s)\n",
diff --git a/src/pcr.h b/src/pcr.h
index 79547bd..dd8311a 100644
--- a/src/pcr.h
+++ b/src/pcr.h
@@ -1,3 +1,3 @@ 
  int tpm2_pcr_supported(void);
-int tpm2_pcr_read(const char *algo_name, int idx, uint8_t *hwpcr,
+int tpm2_pcr_read(const char *algo_name, uint32_t pcrHandle, uint8_t *hwpcr,
  		 int len, char **errmsg);
diff --git a/src/pcr_tss.c b/src/pcr_tss.c
index feb1ff7..5e00524 100644
--- a/src/pcr_tss.c
+++ b/src/pcr_tss.c
@@ -106,7 +106,7 @@  static TPM2_ALG_ID algo_to_tss2(const char *algo_name)
  	return TPM2_ALG_ERROR;
  }

-int tpm2_pcr_read(const char *algo_name, int idx, uint8_t *hwpcr,
+int tpm2_pcr_read(const char *algo_name, uint32_t pcrHandle, uint8_t *hwpcr,
  		 int len, char **errmsg)
  {
  	TSS2_ABI_VERSION abi_version = {
@@ -140,7 +140,7 @@  int tpm2_pcr_read(const char *algo_name, int idx, uint8_t *hwpcr,
  		}
  	};

-	pcr_select_in.pcrSelections[0].pcrSelect[idx / 8] = (1 << (idx % 8));
+	pcr_select_in.pcrSelections[0].pcrSelect[pcrHandle / 8] = (1 << (pcrHandle % 8));

  	ret = Esys_Initialize(&ctx, NULL, &abi_version);
  	if (ret != TPM2_RC_SUCCESS) {
diff --git a/src/pcr_tsspcrread.c b/src/pcr_tsspcrread.c
index 462f270..118c7d2 100644
--- a/src/pcr_tsspcrread.c
+++ b/src/pcr_tsspcrread.c
@@ -68,7 +68,7 @@  int tpm2_pcr_supported(void)
  	return 1;
  }

-int tpm2_pcr_read(const char *algo_name, int idx, uint8_t *hwpcr,
+int tpm2_pcr_read(const char *algo_name, uint32_t pcrHandle, uint8_t *hwpcr,
  		 int len, char **errmsg)
  {
  	FILE *fp;
@@ -77,7 +77,7 @@  int tpm2_pcr_read(const char *algo_name, int idx, uint8_t *hwpcr,
  	int ret;

  	sprintf(cmd, "%s -halg %s -ha %d -ns 2> /dev/null",
-		path, algo_name, idx);
+		path, algo_name, pcrHandle);
  	fp = popen(cmd, "r");
  	if (!fp) {
  		ret = asprintf(errmsg, "popen failed: %s", strerror(errno));