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ima-evm-utils: calculate the per TPM bank boot_aggregate

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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 PCRs 0 - 7.

Reading the TPM PCRs requires root permission, unless access to the
device (/dev/tpm0 or /dev/tpmrm0) has been granted.

Prior to calculating the boot_aggregate, the TPM PCRs themselves should
be validated by walking the TPM event log and re-calculating the PCRs.
(Such a test should be included as part of the TSS regression testsuites.)

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Mimi Zohar 2020-02-24 17:25:48 -05:00
parent 03f99ea6d0
commit dc00c92adf
1 changed files with 72 additions and 0 deletions
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72
src/evmctl.c
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@ -1900,6 +1900,77 @@ static int cmd_ima_measurement(struct command *cmd)
return ima_measurement(file);
}
static void calc_bootaggr(struct tpm_bank_info *bank)
{
EVP_MD_CTX *pctx;
unsigned int mdlen;
const EVP_MD *md;
#if OPENSSL_VERSION_NUMBER < 0x10100000
EVP_MD_CTX ctx;
pctx = &ctx;
#else
pctx = EVP_MD_CTX_new();
#endif
int err = 0;
int i;
md = EVP_get_digestbyname(bank->algo_name);
err = EVP_DigestInit(pctx, md);
if (!err) {
printf("EVP_DigestInit() failed\n");
goto out;
}
for (i = 0; i < 8; i++) {
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");
goto out;
}
out:
printf("%s:", bank->algo_name);
imaevm_hexdump(bank->digest, bank->digest_size);
#if OPENSSL_VERSION_NUMBER >= 0x10100000
EVP_MD_CTX_free(pctx);
#endif
}
/*
* 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.
*/
static int cmd_ima_bootaggr(struct command *cmd)
{
struct tpm_bank_info *tpm_banks;
int num_banks = 0;
int i;
tpm_banks = init_tpm_banks(&num_banks);
if (read_tpm_banks(num_banks, tpm_banks) != 0) {
log_info("Failed to read any TPM PCRs\n");
return -1;
}
for (i = 0; i < num_banks; i++) {
if (!tpm_banks[i].supported)
continue;
calc_bootaggr(&tpm_banks[i]);
}
return 0;
}
static void print_usage(struct command *cmd)
{
printf("usage: %s %s\n", cmd->name, cmd->arg ? cmd->arg : "");
@ -2015,6 +2086,7 @@ struct command cmds[] = {
{"ima_setxattr", cmd_setxattr_ima, 0, "[--sigfile file]", "Set IMA signature from sigfile\n"},
{"ima_hash", cmd_hash_ima, 0, "file", "Make file content hash.\n"},
{"ima_measurement", cmd_ima_measurement, 0, "file", "Verify measurement list (experimental).\n"},
{"ima_boot_aggregate", cmd_ima_bootaggr, 0, "", "Calculate per TPM bank boot_aggregate digests\n"},
{"ima_fix", cmd_ima_fix, 0, "[-t fdsxm] path", "Recursively fix IMA/EVM xattrs in fix mode.\n"},
{"ima_clear", cmd_ima_clear, 0, "[-t fdsxm] path", "Recursively remove IMA/EVM xattrs.\n"},
{"sign_hash", cmd_sign_hash, 0, "[--key key] [--pass [password]", "Sign hashes from shaXsum output.\n"},