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Subject[PATCH 2/5] tpm: Change calc_tpm2_event_size signature
Date
From: Bartosz Szczepanek <bsz@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 <bsz@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
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