[PATCH 2/5] tpm: Change calc_tpm2_event_size signature

[bsz]

From: Bartosz Szczepanek <b...@semihalf.com>

Pass tcg_efi_specid_event as an argument instead of tcg_pcr_event, as the
former is what is actually needed to compute event size. tcg_pcr_event
structure describes TPM event log header (even though its name), from where
efispecid can be extracted -- it seems cleaner and less misleading to do it
out of calc_tpm2_event_size function.

Also, use ssize_t instead of int for event log size.

Signed-off-by: Bartosz Szczepanek <b...@semihalf.com>
---
 lib/tpm.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/lib/tpm.c b/lib/tpm.c
index aaeeafe52426..263ccfdaefa5 100644
--- a/lib/tpm.c
+++ b/lib/tpm.c
@@ -15,6 +15,7 @@
 #include <linux/export.h>
 #include <linux/string.h>
 #include <linux/tpm_eventlog.h>
+#include <linux/errno.h>
 
 /*
  * calc_tpm2_event_size() - calculate the event size, where event
@@ -23,19 +24,18 @@
  * Family "2.0".
 
  * @event: event whose size is to be calculated.
- * @event_header: the first event in the event log.
+ * @efispecid: pointer to structure describing algorithms used.
  *
- * Returns size of the event. If it is an invalid event, returns 0.
+ * Returns size of the event. If it is an invalid event, returns -EINVAL.
  */
-int calc_tpm2_event_size(struct tcg_pcr_event2 *event,
-                        struct tcg_pcr_event *event_header)
+ssize_t calc_tpm2_event_size(struct tcg_pcr_event2 *event,
+                            struct tcg_efi_specid_event *efispecid)
 {
-       struct tcg_efi_specid_event *efispecid;
        struct tcg_event_field *event_field;
        void *marker;
        void *marker_start;
        u32 halg_size;
-       size_t size;
+       ssize_t size;
        u16 halg;
        int i;
        int j;
@@ -45,11 +45,9 @@ int calc_tpm2_event_size(struct tcg_pcr_event2 *event,
        marker = marker + sizeof(event->pcr_idx) + sizeof(event->event_type)
                + sizeof(event->count);
 
-       efispecid = (struct tcg_efi_specid_event *)event_header->event;
-
        /* Check if event is malformed. */
        if (event->count > efispecid->num_algs)
-               return 0;
+               return -EINVAL;
 
        for (i = 0; i < event->count; i++) {
                halg_size = sizeof(event->digests[i].alg_id);
@@ -64,7 +62,7 @@ int calc_tpm2_event_size(struct tcg_pcr_event2 *event,
                }
                /* Algorithm without known length. Such event is unparseable. */
                if (j == efispecid->num_algs)
-                       return 0;
+                       return -EINVAL;
        }
 
        event_field = (struct tcg_event_field *)marker;
@@ -73,7 +71,7 @@ int calc_tpm2_event_size(struct tcg_pcr_event2 *event,
        size = marker - marker_start;
 
        if ((event->event_type == 0) && (event_field->event_size == 0))
-               return 0;
+               return -EINVAL;
 
        return size;
 }
-- 
2.14.4