diff mbox series

[03/11] tpm: add cursor based buffer functions for response parsing

Message ID 20221209160611.30207-4-James.Bottomley@HansenPartnership.com (mailing list archive)
State New, archived
Headers show
Series add integrity and security to TPM2 transactions | expand

Commit Message

James Bottomley Dec. 9, 2022, 4:06 p.m. UTC
It's very convenient when parsing responses to have a cursor you
simply move over the response extracting the data.  Add such cursor
functions for the TPM unsigned integer types.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
 drivers/char/tpm/tpm-buf.c | 29 +++++++++++++++++++++++++++++
 include/linux/tpm.h        |  3 +++
 2 files changed, 32 insertions(+)

Comments

Jarkko Sakkinen Dec. 12, 2022, 12:50 a.m. UTC | #1
On Fri, Dec 09, 2022 at 11:06:03AM -0500, James Bottomley wrote:
> It's very convenient when parsing responses to have a cursor you
> simply move over the response extracting the data.  Add such cursor
> functions for the TPM unsigned integer types.
> 
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

Saying that something is convenient is not really an argument.

What you are going to use it for? Is it complex enough that what we have
not doesn't scale. I'd just answer these questions and write more
reasonable commit message.

BR, Jarkko
James Bottomley Dec. 12, 2022, 3:13 a.m. UTC | #2
On Mon, 2022-12-12 at 00:50 +0000, Jarkko Sakkinen wrote:
> On Fri, Dec 09, 2022 at 11:06:03AM -0500, James Bottomley wrote:
> > It's very convenient when parsing responses to have a cursor you
> > simply move over the response extracting the data.  Add such cursor
> > functions for the TPM unsigned integer types.
> > 
> > Signed-off-by: James Bottomley
> > <James.Bottomley@HansenPartnership.com>
> 
> Saying that something is convenient is not really an argument.
> 
> What you are going to use it for? Is it complex enough that what we
> have not doesn't scale. I'd just answer these questions and write
> more reasonable commit message.

It's all used int patch 6 which gets into the complex building of
authenticated and hmac'd requests and responses via sessions using
these primitives.

James
Jarkko Sakkinen Dec. 26, 2022, 8:06 p.m. UTC | #3
On Sun, Dec 11, 2022 at 10:13:12PM -0500, James Bottomley wrote:
> On Mon, 2022-12-12 at 00:50 +0000, Jarkko Sakkinen wrote:
> > On Fri, Dec 09, 2022 at 11:06:03AM -0500, James Bottomley wrote:
> > > It's very convenient when parsing responses to have a cursor you
> > > simply move over the response extracting the data.  Add such cursor
> > > functions for the TPM unsigned integer types.
> > > 
> > > Signed-off-by: James Bottomley
> > > <James.Bottomley@HansenPartnership.com>
> > 
> > Saying that something is convenient is not really an argument.
> > 
> > What you are going to use it for? Is it complex enough that what we
> > have not doesn't scale. I'd just answer these questions and write
> > more reasonable commit message.
> 
> It's all used int patch 6 which gets into the complex building of
> authenticated and hmac'd requests and responses via sessions using
> these primitives.

Again state obvious, even if you think it is obvious. It is really useful
to have that kind of that as refresher in the commit log.

I'm setting rpi 3b + tpm2 chip gpio to try this out. I thought it would be
a cool test sytem because later on I can test both fTPM in TZ and SPI dTPM
with it...

BR, Jarkko
diff mbox series

Patch

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index f1d48f22d4b4..046b00bf7a81 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -7,6 +7,8 @@ 
 #include <linux/module.h>
 #include <linux/tpm.h>
 
+#include <asm/unaligned.h>
+
 static int __tpm_buf_init(struct tpm_buf *buf)
 {
 	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
@@ -155,3 +157,30 @@  void tpm_buf_append_2b(struct tpm_buf *buf, struct tpm_buf *tpm2b)
 	tpm_buf_reset_int(tpm2b);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_append_2b);
+
+/* functions for unmarshalling data and moving the cursor */
+u8 tpm_get_inc_u8(const u8 **ptr)
+{
+	return *((*ptr)++);
+}
+EXPORT_SYMBOL_GPL(tpm_get_inc_u8);
+
+u16 tpm_get_inc_u16(const u8 **ptr)
+{
+	u16 val;
+
+	val = get_unaligned_be16(*ptr);
+	*ptr += sizeof(val);
+	return val;
+}
+EXPORT_SYMBOL_GPL(tpm_get_inc_u16);
+
+u32 tpm_get_inc_u32(const u8 **ptr)
+{
+	u32 val;
+
+	val = get_unaligned_be32(*ptr);
+	*ptr += sizeof(val);
+	return val;
+}
+EXPORT_SYMBOL_GPL(tpm_get_inc_u32);
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index f2d4dab6d832..f7cff1d114b0 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -335,6 +335,9 @@  void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value);
 void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value);
 void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value);
 void tpm_buf_append_2b(struct tpm_buf *buf, struct tpm_buf *tpm2b);
+u8 tpm_get_inc_u8(const u8 **ptr);
+u16 tpm_get_inc_u16(const u8 **ptr);
+u32 tpm_get_inc_u32(const u8 **ptr);
 
 /*
  * Check if TPM device is in the firmware upgrade mode.