Introducing encryption sessions changes where the return parameters
are located in the buffer because if a return session is present
they're 4 bytes beyond the header with those 4 bytes showing the
parameter length. If there is no return session, then they're in the
usual place immediately after the header. The tpm_buf_parameters()
encapsulates this calculation and should be used everywhere
&buf.data[TPM_HEADER_SIZE] is used now
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/char/tpm/tpm-buf.c | 10 ++++++++++
drivers/char/tpm/tpm.h | 2 ++
2 files changed, 12 insertions(+)
diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index f56350123a08..a5d793d8180d 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -190,3 +190,13 @@ u32 tpm_get_inc_u32(const u8 **ptr)
return val;
}
EXPORT_SYMBOL_GPL(tpm_get_inc_u32);
+
+u8 *tpm_buf_parameters(struct tpm_buf *buf)
+{
+ int offset = TPM_HEADER_SIZE;
+
+ if (tpm_buf_tag(buf) == TPM2_ST_SESSIONS)
+ offset += 4;
+
+ return &buf->data[offset];
+}
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index ebead8e4c3fe..c88eee6376e4 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -311,6 +311,8 @@ u8 tpm_get_inc_u8(const u8 **ptr);
u16 tpm_get_inc_u16(const u8 **ptr);
u32 tpm_get_inc_u32(const u8 **ptr);
+u8 *tpm_buf_parameters(struct tpm_buf *buf);
+
/* opaque structure, holds auth session parameters like the session key */
struct tpm2_auth;
--
2.16.4
