[Skiboot] [PATCH v2 04/14] libstb/stb.c: change tb_measure() to use flash_lookup_resource_name()
Claudio Carvalho
cclaudio at linux.vnet.ibm.com
Thu Aug 31 17:24:35 AEST 2017
Trustedboot measures only images stored in known PNOR partitions. With
the flash_lookup_resource_name(), the PNOR partition information don't
need to be duplicated in libstb for trustedboot.
Additionally, an image can be measured to a PCR only if a PCR number has
been mapped to the respective partition.
This adds the pcr_map() function and replaces stb_resource_lookup() by
both flash_lookup_resource_name() and pcr_map().
Signed-off-by: Claudio Carvalho <cclaudio at linux.vnet.ibm.com>
---
libstb/stb.c | 76 +++++++++++++++++++++++++++++-------------------------------
1 file changed, 37 insertions(+), 39 deletions(-)
diff --git a/libstb/stb.c b/libstb/stb.c
index 949f81c..ed34c6a 100644
--- a/libstb/stb.c
+++ b/libstb/stb.c
@@ -34,8 +34,6 @@ static bool trusted_mode = false;
static struct rom_driver_ops *rom_driver = NULL;
-#define MAX_RESOURCE_NAME 15
-
/*
* This maps a PCR for each resource we can measure. The PCR number is
* mapped according to the TCG PC Client Platform Firmware Profile
@@ -43,21 +41,23 @@ static struct rom_driver_ops *rom_driver = NULL;
* Only resources included in this whitelist can be measured.
*/
static struct {
-
- /* PNOR partition id */
enum resource_id id;
-
- /* PCR mapping for the resource id */
TPM_Pcr pcr;
-
- /* Resource name */
- const char name[MAX_RESOURCE_NAME+1];
-
-} resource_map[] = {
- { RESOURCE_ID_KERNEL, PCR_4, "BOOTKERNEL" },
- { RESOURCE_ID_CAPP, PCR_2, "CAPP"},
+} resources[] = {
+ { RESOURCE_ID_KERNEL, PCR_4 },
+ { RESOURCE_ID_CAPP, PCR_2 },
};
+static TPM_Pcr map_pcr(enum resource_id id)
+{
+ int i;
+ for (i = 0; i < ARRAY_SIZE(resources); i++) {
+ if (resources[i].id == id)
+ return resources[i].pcr;
+ }
+ return -1;
+}
+
struct event_hash {
const unsigned char *sha1;
const unsigned char *sha256;
@@ -76,15 +76,6 @@ static struct event_hash evFF = {
"\xfd\x0e"
};
-static int stb_resource_lookup(enum resource_id id)
-{
- int i;
- for (i = 0; i < ARRAY_SIZE(resource_map); i++)
- if (resource_map[i].id == id)
- return i;
- return -1;
-}
-
static void sb_enforce(void)
{
/*
@@ -188,9 +179,10 @@ int stb_final(void)
int tb_measure(enum resource_id id, void *buf, size_t len)
{
- int r;
uint8_t digest[SHA512_DIGEST_LENGTH];
const uint8_t *digestp;
+ const char *name;
+ TPM_Pcr pcr;
digestp = NULL;
if (!trusted_mode) {
@@ -198,17 +190,25 @@ int tb_measure(enum resource_id id, void *buf, size_t len)
"trusted_mode=0\n", __func__, id);
return STB_TRUSTED_MODE_DISABLED;
}
- r = stb_resource_lookup(id);
- if (r == -1) {
+ name = flash_map_resource_name(id);
+ if (!name) {
/**
- * @fwts-label STBMeasureResourceNotMapped
- * @fwts-advice The resource is not registered in the resource_map[]
- * array, but it should be otherwise the resource cannot be
- * measured if trusted mode is on.
+ * @fwts-label ResourceNotMeasuredUnknown
+ * @fwts-advice This is a bug in the tb_measure() caller, which
+ * is passing an unknown resource_id.
*/
- prlog(PR_ERR, "STB: %s failed, resource %d not mapped\n",
- __func__, id);
- return STB_ARG_ERROR;
+ prerror("STB: resource NOT MEASURED, resource_id=%d unknown\n", id);
+ return -1;
+ }
+ pcr = map_pcr(id);
+ if (pcr == -1) {
+ /**
+ * @fwts-label ResourceNotMappedToPCR
+ * @fwts-advice This is a bug. The resource cannot be measured
+ * because it is not mapped to a PCR in the resources[] array.
+ */
+ prerror("STB: %s NOT MEASURED, it's not mapped to a PCR\n", name);
+ return -1;
}
if (!buf) {
/**
@@ -218,7 +218,7 @@ int tb_measure(enum resource_id id, void *buf, size_t len)
* bug in the framework.
*/
prlog(PR_ERR, "STB: %s failed: resource %s, buf null\n",
- __func__, resource_map[r].name);
+ __func__, name);
return STB_ARG_ERROR;
}
memset(digest, 0, SHA512_DIGEST_LENGTH);
@@ -239,8 +239,7 @@ int tb_measure(enum resource_id id, void *buf, size_t len)
(void*)((uint8_t*)buf + SECURE_BOOT_HEADERS_SIZE),
len - SECURE_BOOT_HEADERS_SIZE, digest);
- prlog(PR_INFO, "STB: %s sha512 hash re-calculated\n",
- resource_map[r].name);
+ prlog(PR_INFO, "STB: %s sha512 hash re-calculated\n", name);
if (memcmp(digestp, digest, TPM_ALG_SHA256_SIZE) != 0) {
prlog(PR_ALERT, "STB: HASH IN CONTAINER DOESN'T MATCH CONTENT!\n");
prlog(PR_ALERT, "STB: Container hash:\n");
@@ -253,8 +252,7 @@ int tb_measure(enum resource_id id, void *buf, size_t len)
}
} else {
rom_driver->sha512(buf, len, digest);
- prlog(PR_INFO, "STB: %s sha512 hash calculated\n",
- resource_map[r].name);
+ prlog(PR_INFO, "STB: %s sha512 hash calculated\n", name);
}
#ifdef STB_DEBUG
@@ -267,10 +265,10 @@ int tb_measure(enum resource_id id, void *buf, size_t len)
* algorithm, the sha512 hash is truncated to match the size required
* by each PCR bank.
*/
- return tpm_extendl(resource_map[r].pcr,
+ return tpm_extendl(pcr,
TPM_ALG_SHA256, digest, TPM_ALG_SHA256_SIZE,
TPM_ALG_SHA1, digest, TPM_ALG_SHA1_SIZE,
- EV_ACTION, resource_map[r].name);
+ EV_ACTION, name);
}
int sb_verify(enum resource_id id, void *buf, size_t len)
--
2.7.4
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