[tpmdd-devel] tpm: fix byte order related arithmetic inconsistency in tpm_getcap()

Submitted by Jarkko Sakkinen on May 7, 2017, 5:50 p.m.

Details

Message ID 20170507175002.9558-1-jarkko.sakkinen@linux.intel.com
State New
Headers show

Commit Message

Jarkko Sakkinen May 7, 2017, 5:50 p.m.
You should not do arithmetic with __be32 or __le32 types because
sometimes it results incorrect results. Calculations must be done only
with integers that are in in the CPU byte order. This commit migrates
tpm_getcap() to struct tpm_buf in order to sort out these issues.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
Now this should work as Robertos patches move byte order conversion
where it should be. Sadly I'm out of reach to my Dell E6400 laptop
that I use for TPM 1.2 testing.
 drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++--------------
 drivers/char/tpm/tpm.h           | 13 -------------
 2 files changed, 16 insertions(+), 27 deletions(-)

Comments

Jarkko Sakkinen May 9, 2017, 2:13 p.m.
On Sun, May 07, 2017 at 08:50:02PM +0300, Jarkko Sakkinen wrote:
> You should not do arithmetic with __be32 or __le32 types because
> sometimes it results incorrect results. Calculations must be done only
> with integers that are in in the CPU byte order. This commit migrates
> tpm_getcap() to struct tpm_buf in order to sort out these issues.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
> Now this should work as Robertos patches move byte order conversion
> where it should be. Sadly I'm out of reach to my Dell E6400 laptop
> that I use for TPM 1.2 testing.
>  drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++--------------
>  drivers/char/tpm/tpm.h           | 13 -------------
>  2 files changed, 16 insertions(+), 27 deletions(-)

I've now tested this with TPM 1.2. Any complains?

/Jarkko

> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 4ed08ab4d2a8..7436422458c7 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -552,31 +552,33 @@ static const struct tpm_input_header tpm_getcap_header = {
>  ssize_t tpm_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
>  		   const char *desc, size_t min_cap_length)
>  {
> -	struct tpm_cmd_t tpm_cmd;
> +	struct tpm_buf buf;
>  	int rc;
>  
> -	tpm_cmd.header.in = tpm_getcap_header;
> +	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
> +	if (rc)
> +		return rc;
> +
>  	if (subcap_id == TPM_CAP_VERSION_1_1 ||
>  	    subcap_id == TPM_CAP_VERSION_1_2) {
> -		tpm_cmd.params.getcap_in.cap = cpu_to_be32(subcap_id);
> -		/*subcap field not necessary */
> -		tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(0);
> -		tpm_cmd.header.in.length -= cpu_to_be32(sizeof(__be32));
> +		tpm_buf_append_u32(&buf, subcap_id);
> +		tpm_buf_append_u32(&buf, 0);
>  	} else {
>  		if (subcap_id == TPM_CAP_FLAG_PERM ||
>  		    subcap_id == TPM_CAP_FLAG_VOL)
> -			tpm_cmd.params.getcap_in.cap =
> -				cpu_to_be32(TPM_CAP_FLAG);
> +			tpm_buf_append_u32(&buf, TPM_CAP_FLAG);
>  		else
> -			tpm_cmd.params.getcap_in.cap =
> -				cpu_to_be32(TPM_CAP_PROP);
> -		tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
> -		tpm_cmd.params.getcap_in.subcap = cpu_to_be32(subcap_id);
> +			tpm_buf_append_u32(&buf, TPM_CAP_PROP);
> +
> +		tpm_buf_append_u32(&buf, 4);
> +		tpm_buf_append_u32(&buf, subcap_id);
>  	}
> -	rc = tpm_transmit_cmd(chip, NULL, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
> +	rc = tpm_transmit_cmd(chip, NULL, buf.data, TPM_INTERNAL_RESULT_SIZE,
>  			      min_cap_length, 0, desc);
>  	if (!rc)
> -		*cap = tpm_cmd.params.getcap_out.cap;
> +		*cap = *(cap_t *)&buf.data[TPM_HEADER_SIZE + 4];
> +
> +	tpm_buf_destroy(&buf);
>  	return rc;
>  }
>  EXPORT_SYMBOL_GPL(tpm_getcap);
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index e81d8c7acb39..dd1173427fb2 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -339,17 +339,6 @@ enum tpm_sub_capabilities {
>  	TPM_CAP_PROP_TIS_DURATION = 0x120,
>  };
>  
> -struct	tpm_getcap_params_in {
> -	__be32	cap;
> -	__be32	subcap_size;
> -	__be32	subcap;
> -} __packed;
> -
> -struct	tpm_getcap_params_out {
> -	__be32	cap_size;
> -	cap_t	cap;
> -} __packed;
> -
>  struct	tpm_readpubek_params_out {
>  	u8	algorithm[4];
>  	u8	encscheme[2];
> @@ -399,10 +388,8 @@ struct tpm_startup_in {
>  } __packed;
>  
>  typedef union {
> -	struct	tpm_getcap_params_out getcap_out;
>  	struct	tpm_readpubek_params_out readpubek_out;
>  	u8	readpubek_out_buffer[sizeof(struct tpm_readpubek_params_out)];
> -	struct	tpm_getcap_params_in getcap_in;
>  	struct	tpm_pcrread_in	pcrread_in;
>  	struct	tpm_pcrread_out	pcrread_out;
>  	struct	tpm_pcrextend_in pcrextend_in;
> -- 
> 2.11.0
> 

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Jason Gunthorpe May 9, 2017, 3:13 p.m.
On Tue, May 09, 2017 at 05:13:53PM +0300, Jarkko Sakkinen wrote:
> On Sun, May 07, 2017 at 08:50:02PM +0300, Jarkko Sakkinen wrote:
> > You should not do arithmetic with __be32 or __le32 types because
> > sometimes it results incorrect results. Calculations must be done only
> > with integers that are in in the CPU byte order. This commit migrates
> > tpm_getcap() to struct tpm_buf in order to sort out these issues.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > Now this should work as Robertos patches move byte order conversion
> > where it should be. Sadly I'm out of reach to my Dell E6400 laptop
> > that I use for TPM 1.2 testing.
> >  drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++--------------
> >  drivers/char/tpm/tpm.h           | 13 -------------
> >  2 files changed, 16 insertions(+), 27 deletions(-)
> 
> I've now tested this with TPM 1.2. Any complains?

Seems reasonable, but which linke had the problematic arithmetic?

Jason

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Jarkko Sakkinen May 10, 2017, 12:34 p.m.
On Tue, May 09, 2017 at 09:13:08AM -0600, Jason Gunthorpe wrote:
> On Tue, May 09, 2017 at 05:13:53PM +0300, Jarkko Sakkinen wrote:
> > On Sun, May 07, 2017 at 08:50:02PM +0300, Jarkko Sakkinen wrote:
> > > You should not do arithmetic with __be32 or __le32 types because
> > > sometimes it results incorrect results. Calculations must be done only
> > > with integers that are in in the CPU byte order. This commit migrates
> > > tpm_getcap() to struct tpm_buf in order to sort out these issues.
> > > 
> > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > Now this should work as Robertos patches move byte order conversion
> > > where it should be. Sadly I'm out of reach to my Dell E6400 laptop
> > > that I use for TPM 1.2 testing.
> > >  drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++--------------
> > >  drivers/char/tpm/tpm.h           | 13 -------------
> > >  2 files changed, 16 insertions(+), 27 deletions(-)
> > 
> > I've now tested this with TPM 1.2. Any complains?
> 
> Seems reasonable, but which linke had the problematic arithmetic?
> 
> Jason

Arithmetic should work but it's not a good practice to do additions,
substractions or multiplications in any other byte order than the CPU
byte order.

sparse also complains about this.

/Jarkko

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Luc Van Oostenryck May 10, 2017, 11:41 p.m.
On Wed, May 10, 2017 at 2:34 PM, Jarkko Sakkinen
<jarkko.sakkinen@linux.intel.com> wrote:

> Arithmetic should work but it's not a good practice to do additions,
> substractions or multiplications in any other byte order than the CPU
> byte order.
>
> sparse also complains about this.
>
> /Jarkko

Arithmetic should work?
let's try with 0x0080:
in native order: 0x0080 + 0x0080 = 0x0100
in reverse order: 0x8000 + 0x8000 = 0x0000 != swap16(0x0100)

Or do I misunderstand what you mean by "arithmetic should work"?

-- Luc Van Oostenryck

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Jarkko Sakkinen May 11, 2017, 10:16 a.m.
On Thu, May 11, 2017 at 01:41:15AM +0200, Luc Van Oostenryck wrote:
> On Wed, May 10, 2017 at 2:34 PM, Jarkko Sakkinen
> <jarkko.sakkinen@linux.intel.com> wrote:
> 
> > Arithmetic should work but it's not a good practice to do additions,
> > substractions or multiplications in any other byte order than the CPU
> > byte order.
> >
> > sparse also complains about this.
> >
> > /Jarkko
> 
> Arithmetic should work?
> let's try with 0x0080:
> in native order: 0x0080 + 0x0080 = 0x0100
> in reverse order: 0x8000 + 0x8000 = 0x0000 != swap16(0x0100)
> 
> Or do I misunderstand what you mean by "arithmetic should work"?
> 
> -- Luc Van Oostenryck

I was referring to the specific code snippet in tpm-interface.c.

/Jarkko

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Jarkko Sakkinen May 15, 2017, 11:36 a.m.
On Wed, May 10, 2017 at 03:34:58PM +0300, Jarkko Sakkinen wrote:
> On Tue, May 09, 2017 at 09:13:08AM -0600, Jason Gunthorpe wrote:
> > On Tue, May 09, 2017 at 05:13:53PM +0300, Jarkko Sakkinen wrote:
> > > On Sun, May 07, 2017 at 08:50:02PM +0300, Jarkko Sakkinen wrote:
> > > > You should not do arithmetic with __be32 or __le32 types because
> > > > sometimes it results incorrect results. Calculations must be done only
> > > > with integers that are in in the CPU byte order. This commit migrates
> > > > tpm_getcap() to struct tpm_buf in order to sort out these issues.
> > > > 
> > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > > Now this should work as Robertos patches move byte order conversion
> > > > where it should be. Sadly I'm out of reach to my Dell E6400 laptop
> > > > that I use for TPM 1.2 testing.
> > > >  drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++--------------
> > > >  drivers/char/tpm/tpm.h           | 13 -------------
> > > >  2 files changed, 16 insertions(+), 27 deletions(-)
> > > 
> > > I've now tested this with TPM 1.2. Any complains?
> > 
> > Seems reasonable, but which linke had the problematic arithmetic?
> > 
> > Jason
> 
> Arithmetic should work but it's not a good practice to do additions,
> substractions or multiplications in any other byte order than the CPU
> byte order.
> 
> sparse also complains about this.

Can I get your Reviewed-by for this one?

/Jarkko

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Jason Gunthorpe May 15, 2017, 3:39 p.m.
On Mon, May 15, 2017 at 02:36:02PM +0300, Jarkko Sakkinen wrote:
> On Wed, May 10, 2017 at 03:34:58PM +0300, Jarkko Sakkinen wrote:
> > On Tue, May 09, 2017 at 09:13:08AM -0600, Jason Gunthorpe wrote:
> > > On Tue, May 09, 2017 at 05:13:53PM +0300, Jarkko Sakkinen wrote:
> > > > On Sun, May 07, 2017 at 08:50:02PM +0300, Jarkko Sakkinen wrote:
> > > > > You should not do arithmetic with __be32 or __le32 types because
> > > > > sometimes it results incorrect results. Calculations must be done only
> > > > > with integers that are in in the CPU byte order. This commit migrates
> > > > > tpm_getcap() to struct tpm_buf in order to sort out these issues.
> > > > > 
> > > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > > > Now this should work as Robertos patches move byte order conversion
> > > > > where it should be. Sadly I'm out of reach to my Dell E6400 laptop
> > > > > that I use for TPM 1.2 testing.
> > > > >  drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++--------------
> > > > >  drivers/char/tpm/tpm.h           | 13 -------------
> > > > >  2 files changed, 16 insertions(+), 27 deletions(-)
> > > > 
> > > > I've now tested this with TPM 1.2. Any complains?
> > > 
> > > Seems reasonable, but which linke had the problematic arithmetic?
> > > 
> > > Jason
> > 
> > Arithmetic should work but it's not a good practice to do additions,
> > substractions or multiplications in any other byte order than the CPU
> > byte order.
> > 
> > sparse also complains about this.
> 
> Can I get your Reviewed-by for this one?

Sure, but I'm still wondering what the sparse warning was?

Jason

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Jarkko Sakkinen May 24, 2017, 4:59 p.m.
On Mon, May 15, 2017 at 09:39:34AM -0600, Jason Gunthorpe wrote:
> On Mon, May 15, 2017 at 02:36:02PM +0300, Jarkko Sakkinen wrote:
> > On Wed, May 10, 2017 at 03:34:58PM +0300, Jarkko Sakkinen wrote:
> > > On Tue, May 09, 2017 at 09:13:08AM -0600, Jason Gunthorpe wrote:
> > > > On Tue, May 09, 2017 at 05:13:53PM +0300, Jarkko Sakkinen wrote:
> > > > > On Sun, May 07, 2017 at 08:50:02PM +0300, Jarkko Sakkinen wrote:
> > > > > > You should not do arithmetic with __be32 or __le32 types because
> > > > > > sometimes it results incorrect results. Calculations must be done only
> > > > > > with integers that are in in the CPU byte order. This commit migrates
> > > > > > tpm_getcap() to struct tpm_buf in order to sort out these issues.
> > > > > > 
> > > > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > > > > Now this should work as Robertos patches move byte order conversion
> > > > > > where it should be. Sadly I'm out of reach to my Dell E6400 laptop
> > > > > > that I use for TPM 1.2 testing.
> > > > > >  drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++--------------
> > > > > >  drivers/char/tpm/tpm.h           | 13 -------------
> > > > > >  2 files changed, 16 insertions(+), 27 deletions(-)
> > > > > 
> > > > > I've now tested this with TPM 1.2. Any complains?
> > > > 
> > > > Seems reasonable, but which linke had the problematic arithmetic?
> > > > 
> > > > Jason
> > > 
> > > Arithmetic should work but it's not a good practice to do additions,
> > > substractions or multiplications in any other byte order than the CPU
> > > byte order.
> > > 
> > > sparse also complains about this.
> > 
> > Can I get your Reviewed-by for this one?
> 
> Sure, but I'm still wondering what the sparse warning was?
> 
> Jason

This type of errors

drivers/char/tpm//tpm-interface.c:492:42: warning: bad assignment (-=) to restricted __be32

/Jarkko

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Patch hide | download patch | download mbox

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 4ed08ab4d2a8..7436422458c7 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -552,31 +552,33 @@  static const struct tpm_input_header tpm_getcap_header = {
 ssize_t tpm_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 		   const char *desc, size_t min_cap_length)
 {
-	struct tpm_cmd_t tpm_cmd;
+	struct tpm_buf buf;
 	int rc;
 
-	tpm_cmd.header.in = tpm_getcap_header;
+	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
+	if (rc)
+		return rc;
+
 	if (subcap_id == TPM_CAP_VERSION_1_1 ||
 	    subcap_id == TPM_CAP_VERSION_1_2) {
-		tpm_cmd.params.getcap_in.cap = cpu_to_be32(subcap_id);
-		/*subcap field not necessary */
-		tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(0);
-		tpm_cmd.header.in.length -= cpu_to_be32(sizeof(__be32));
+		tpm_buf_append_u32(&buf, subcap_id);
+		tpm_buf_append_u32(&buf, 0);
 	} else {
 		if (subcap_id == TPM_CAP_FLAG_PERM ||
 		    subcap_id == TPM_CAP_FLAG_VOL)
-			tpm_cmd.params.getcap_in.cap =
-				cpu_to_be32(TPM_CAP_FLAG);
+			tpm_buf_append_u32(&buf, TPM_CAP_FLAG);
 		else
-			tpm_cmd.params.getcap_in.cap =
-				cpu_to_be32(TPM_CAP_PROP);
-		tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
-		tpm_cmd.params.getcap_in.subcap = cpu_to_be32(subcap_id);
+			tpm_buf_append_u32(&buf, TPM_CAP_PROP);
+
+		tpm_buf_append_u32(&buf, 4);
+		tpm_buf_append_u32(&buf, subcap_id);
 	}
-	rc = tpm_transmit_cmd(chip, NULL, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
+	rc = tpm_transmit_cmd(chip, NULL, buf.data, TPM_INTERNAL_RESULT_SIZE,
 			      min_cap_length, 0, desc);
 	if (!rc)
-		*cap = tpm_cmd.params.getcap_out.cap;
+		*cap = *(cap_t *)&buf.data[TPM_HEADER_SIZE + 4];
+
+	tpm_buf_destroy(&buf);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm_getcap);
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index e81d8c7acb39..dd1173427fb2 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -339,17 +339,6 @@  enum tpm_sub_capabilities {
 	TPM_CAP_PROP_TIS_DURATION = 0x120,
 };
 
-struct	tpm_getcap_params_in {
-	__be32	cap;
-	__be32	subcap_size;
-	__be32	subcap;
-} __packed;
-
-struct	tpm_getcap_params_out {
-	__be32	cap_size;
-	cap_t	cap;
-} __packed;
-
 struct	tpm_readpubek_params_out {
 	u8	algorithm[4];
 	u8	encscheme[2];
@@ -399,10 +388,8 @@  struct tpm_startup_in {
 } __packed;
 
 typedef union {
-	struct	tpm_getcap_params_out getcap_out;
 	struct	tpm_readpubek_params_out readpubek_out;
 	u8	readpubek_out_buffer[sizeof(struct tpm_readpubek_params_out)];
-	struct	tpm_getcap_params_in getcap_in;
 	struct	tpm_pcrread_in	pcrread_in;
 	struct	tpm_pcrread_out	pcrread_out;
 	struct	tpm_pcrextend_in pcrextend_in;