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ima-evm-utils: read the PCRs for the requested TPM banks

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Read and store the PCRs for the requested banks to compare with the
re-calculated PCR values.

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Mimi Zohar
2020-02-18 10:56:02 -05:00
parent 2f482a6989
commit 3472f9ba9c
1 changed files with 50 additions and 0 deletions
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50
src/evmctl.c
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@@ -1423,6 +1423,7 @@ static int tpm_pcr_read(int idx, uint8_t *pcr, int len)
}
#ifdef HAVE_TSSPCRREAD
static int tpm2_pcrread = 1;
static int tpm2_pcr_read(const char *algo_name, int idx, uint8_t *hwpcr,
int len, char **errmsg)
{
@@ -1464,6 +1465,13 @@ static int tpm2_pcr_read(const char *algo_name, int idx, uint8_t *hwpcr,
return ret;
}
#else
static int tpm2_pcrread = 0;
static int tpm2_pcr_read(const char *algo_name, int idx, uint8_t *hwpcr,
int len, char **errmsg)
{
return -1;
}
#endif
#define TCG_EVENT_NAME_LEN_MAX 255
@@ -1804,9 +1812,47 @@ static void extend_tpm_banks(struct template_entry *entry, int num_banks,
#endif
}
/*
* Attempt to read TPM PCRs from the multiple TPM 2.0 banks.
*
* On success reading from any TPM bank, return 0.
*/
static int read_tpm_banks(int num_banks, struct tpm_bank_info *bank)
{
int tpm_enabled = 0;
char *errmsg = NULL;
int i, j;
int err;
/* Any userspace applications available for reading TPM 2.0 PCRs? */
if (!tpm2_pcrread) {
log_info("Failed to read TPM 2.0 PCRs\n");
return 1;
}
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,
&errmsg);
if (err) {
log_info("Failed to read %s PCRs: (%s)\n",
bank[i].algo_name, errmsg);
free(errmsg);
bank[i].supported = 0;
}
}
if (bank[i].supported)
tpm_enabled = 1;
}
return tpm_enabled ? 0 : 1;
}
static int ima_measurement(const char *file)
{
struct tpm_bank_info *pseudo_banks;
struct tpm_bank_info *tpm_banks;
int num_banks = 0;
uint8_t pcr[NUM_PCRS][SHA_DIGEST_LENGTH] = {{0}};
@@ -1825,6 +1871,7 @@ static int ima_measurement(const char *file)
log_debug_dump(pcr, sizeof(pcr));
pseudo_banks = init_tpm_banks(&num_banks);
tpm_banks = init_tpm_banks(&num_banks);
fp = fopen(file, "rb");
if (!fp) {
@@ -1912,6 +1959,9 @@ static int ima_measurement(const char *file)
if (!verify_failed)
err = 0;
else
read_tpm_banks(num_banks, tpm_banks);
out:
fclose(fp);
return err;