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tpm2-util: split out code that derives "good" TPM2 banks into an strv from pcrphase and generalize it in tpm2-util.c

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That way we can reuse it later from different places.
This commit is contained in:
Lennart Poettering
2022-10-11 18:07:46 +02:00
parent ab250890c0
commit e4481cc512
3 changed files with 50 additions and 22 deletions
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28
src/boot/pcrphase.c
View File

@@ -124,35 +124,19 @@ static int parse_argv(int argc, char *argv[]) {
}
static int determine_banks(struct tpm2_context *c) {
_cleanup_free_ TPMI_ALG_HASH *algs = NULL;
int n_algs, r;
_cleanup_strv_free_ char **l = NULL;
int r;
assert(c);
if (!strv_isempty(arg_banks)) /* Explicitly configured? Then use that */
return 0;
n_algs = tpm2_get_good_pcr_banks(c->esys_context, UINT32_C(1) << TPM_PCR_INDEX_KERNEL_IMAGE, &algs);
if (n_algs <= 0)
return n_algs;
for (int i = 0; i < n_algs; i++) {
const EVP_MD *implementation;
const char *salg;
salg = tpm2_pcr_bank_to_string(algs[i]);
if (!salg)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 operates with unknown PCR algorithm, can't measure.");
implementation = EVP_get_digestbyname(salg);
if (!implementation)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 operates with unsupported PCR algorithm, can't measure.");
r = strv_extend(&arg_banks, EVP_MD_name(implementation));
if (r < 0)
return log_oom();
}
r = tpm2_get_good_pcr_banks_strv(c->esys_context, UINT32_C(1) << TPM_PCR_INDEX_KERNEL_IMAGE, &l);
if (r < 0)
return r;
strv_free_and_replace(arg_banks, l);
return 0;
}

43
src/shared/tpm2-util.c
View File

@@ -730,6 +730,49 @@ int tpm2_get_good_pcr_banks(
return 0;
}
int tpm2_get_good_pcr_banks_strv(
ESYS_CONTEXT *c,
uint32_t pcr_mask,
char ***ret) {
_cleanup_free_ TPMI_ALG_HASH *algs = NULL;
_cleanup_strv_free_ char **l = NULL;
int n_algs;
assert(c);
assert(ret);
n_algs = tpm2_get_good_pcr_banks(c, pcr_mask, &algs);
if (n_algs < 0)
return n_algs;
for (int i = 0; i < n_algs; i++) {
_cleanup_free_ char *n = NULL;
const EVP_MD *implementation;
const char *salg;
salg = tpm2_pcr_bank_to_string(algs[i]);
if (!salg)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 operates with unknown PCR algorithm, can't measure.");
implementation = EVP_get_digestbyname(salg);
if (!implementation)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 operates with unsupported PCR algorithm, can't measure.");
n = strdup(ASSERT_PTR(EVP_MD_name(implementation)));
if (!n)
return log_oom();
ascii_strlower(n); /* OpenSSL uses uppercase digest names, we prefer them lower case. */
if (strv_consume(&l, TAKE_PTR(n)) < 0)
return log_oom();
}
*ret = TAKE_PTR(l);
return 0;
}
static void hash_pin(const char *pin, size_t len, TPM2B_AUTH *auth) {
struct sha256_ctx hash;

1
src/shared/tpm2-util.h
View File

@@ -68,6 +68,7 @@ static inline void Esys_Freep(void *p) {
}
int tpm2_get_good_pcr_banks(ESYS_CONTEXT *c, uint32_t pcr_mask, TPMI_ALG_HASH **ret_banks);
int tpm2_get_good_pcr_banks_strv(ESYS_CONTEXT *c, uint32_t pcr_mask, char ***ret);
#else
struct tpm2_context;