event_log: obtain event log location from SLRT and log SKL measurements

SKL hashes are no longer passed from the bootloader. Measured code and
read-only data are not changed, and all other data is created at runtime
so SKL is able to measure itself, which it now does. Those hashes are
only used for event log entries, PCR was extended as a result of SKINIT
instruction on Dynamic Launch Event.

Signed-off-by: Krystian Hebel <[email protected]>

Author: krystian-hebel

event_log.c

@@ -17,8 +17,10 @@
  */
 
 #include <boot.h>
+#include <sha1sum.h>
+#include <sha256.h>
+#include <slrt.h>
 #include <string.h>
-#include <tags.h>
 #include "tpmlib/tpm.h"
 #include "tpmlib/tpm2_constants.h"
 
@@ -204,9 +206,12 @@ int log_event_tpm20(u32 pcr, u8 sha1[20], u8 sha256[32], char *event)
 int event_log_init(struct tpm *tpm)
 {
     unsigned int min_size;
-    struct skl_tag_evtlog *t = next_of_type(&bootloader_data, SKL_TAG_EVENT_LOG);
+    struct slr_entry_log_info *info;
+    u8 hash[SHA1_DIGEST_SIZE];
 
-    if ( t == NULL || next_of_type(t, SKL_TAG_EVENT_LOG) != NULL )
+    info = next_entry_with_tag(NULL, SLR_ENTRY_LOG_INFO);
+
+    if ( info == NULL || next_entry_with_tag(info, SLR_ENTRY_LOG_INFO) != NULL )
         goto err;
 
     min_size = sizeof (tpm12_event_t);
@@ -227,11 +232,11 @@ int event_log_init(struct tpm *tpm)
     }
 
     /* Note that min_size does not include tpmXX_event_t.event[] entries */
-    if ( t->size < min_size )
+    if ( info->size < min_size )
         goto err;
 
-    ptr_current = evtlog_base = _p(t->address);
-    limit = _p(t->address + t->size);
+    ptr_current = evtlog_base = _p(info->addr);
+    limit = _p(info->addr + info->size);
 
     /* Check for overflow */
     if ( ptr_current > limit )
@@ -245,7 +250,12 @@ int event_log_init(struct tpm *tpm)
     if ( !(_p(limit) < _p(_start) || _p(_start + SLB_SIZE) < _p(ptr_current)) )
         goto err;
 
-    memset(ptr_current, 0, t->size);
+    memset(ptr_current, 0, info->size);
+
+    /* Check if log format matches TPM family */
+    if ((tpm->family == TPM12 && info->format != SLR_LOG_FORMAT_TPM12_TXT) ||
+        (tpm->family == TPM20 && info->format != SLR_LOG_FORMAT_TPM20_TCG))
+        goto err;
 
     /* Write log header */
     {
@@ -266,52 +276,26 @@ int event_log_init(struct tpm *tpm)
     if ( tpm->family == TPM12 ) {
         tpm12_spec_id_ev_t *id = (tpm12_spec_id_ev_t *)ptr_current;
         log_write(&tpm12_id_struct, sizeof(tpm12_id_struct));
-        id->hdr.container_size = t->size;
+        id->hdr.container_size = info->size;
     } else {
         tpm20_spec_id_ev_t *id = (tpm20_spec_id_ev_t *)ptr_current;
         log_write(&tpm20_id_struct, sizeof(tpm20_id_struct));
-        id->el.allocated_event_container_size = t->size;
+        id->el.allocated_event_container_size = info->size;
         id->el.phys_addr = _u(evtlog_base);
     }
 
     /* Log what was done by SKINIT */
+    sha1sum(hash, _start, _end_of_measured - _start);
     if ( tpm->family == TPM12 )
     {
-        struct skl_tag_hash *h = next_of_type(&bootloader_data, SKL_TAG_SKL_HASH);
-
-        while ( h != NULL )
-        {
-            if ( h->algo_id == TPM_ALG_SHA1 )
-                return log_event_tpm12(17, h->digest, "SKINIT");
-
-            h = next_of_type(h, SKL_TAG_SKL_HASH);
-        }
-
-        /* No SHA1 hash was passed by a bootloader? */
-        return 1;
+        return log_event_tpm12(17, hash, "SKINIT");
     }
-     else
+    else if ( tpm->family == TPM20 )
     {
-        struct skl_tag_hash *h = next_of_type(&bootloader_data, SKL_TAG_SKL_HASH);
-        u8 *sha1 = NULL;
-        u8 *sha256 = NULL;
-
-        while ( h != NULL )
-        {
-            if ( h->algo_id == TPM_ALG_SHA1 )
-                sha1 = h->digest;
-
-            if ( h->algo_id == TPM_ALG_SHA256 )
-                sha256 = h->digest;
+        u8 sha256_hash[SHA256_DIGEST_SIZE];
 
-            if ( sha1 != NULL && sha256 != NULL )
-                return log_event_tpm20(17, sha1, sha256, "SKINIT");
-
-            h = next_of_type(h, SKL_TAG_SKL_HASH);
-        }
-
-        /* Either SHA1 or SHA256 hash wasn't passed by a bootloader? */
-        return 1;
+        sha256sum(sha256_hash, _start, _end_of_measured - _start);
+        return log_event_tpm20(17, hash, sha256_hash, "SKINIT");
     }
 
 err:

include/boot.h

@@ -40,6 +40,7 @@
 #define __BOOT_H__
 
 extern const char _start[];
+extern const char _end_of_measured[];
 
 typedef struct __packed sl_header {
     u16 skl_entry_point;