[v4,6/6] tpm: ensure that the output of PCR read contains the correct digest size
diff mbox series

Message ID 20181106150159.1136-7-roberto.sassu@huawei.com
State New
Headers show
Series
  • tpm: retrieve digest size of unknown algorithms from TPM
Related show

Commit Message

Roberto Sassu Nov. 6, 2018, 3:01 p.m. UTC
This patch protects against data corruption that could happen in the bus,
by checking that that the digest size returned by the TPM during a PCR read
matches the size of the algorithm passed as argument to tpm2_pcr_read().

This check is performed after information about the PCR banks has been
retrieved.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

Comments

Jarkko Sakkinen Nov. 8, 2018, 2:08 p.m. UTC | #1
On Tue, Nov 06, 2018 at 04:01:59PM +0100, Roberto Sassu wrote:
> This patch protects against data corruption that could happen in the bus,
> by checking that that the digest size returned by the TPM during a PCR read
> matches the size of the algorithm passed as argument to tpm2_pcr_read().
> 
> This check is performed after information about the PCR banks has been
> retrieved.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
>  drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index e2d5b84286a7..3b0b5b032901 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -187,15 +187,28 @@ struct tpm2_pcr_read_out {
>  int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
>  		  struct tpm_digest *digest_struct, u16 *digest_size_ptr)
>  {
> +	int i;
>  	int rc;
>  	struct tpm_buf buf;
>  	struct tpm2_pcr_read_out *out;
>  	u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
>  	u16 digest_size;
> +	u16 expected_digest_size = 0;
>  
>  	if (pcr_idx >= TPM2_PLATFORM_PCR)
>  		return -EINVAL;
>  
> +	if (!digest_size_ptr) {
> +		for (i = 0; i < chip->nr_active_banks &&
> +		     chip->active_banks[i].alg_id != digest_struct->alg_id; i++)
> +			;

Not sure if the semicolon should be in its own line.
`
> +
> +		if (i == chip->nr_active_banks)
> +			return -EINVAL;
> +
> +		expected_digest_size = chip->active_banks[i].digest_size;
> +	}
> +
>  	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
>  	if (rc)
>  		return rc;
> @@ -215,7 +228,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
>  
>  	out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
>  	digest_size = be16_to_cpu(out->digest_size);
> -	if (digest_size > sizeof(digest_struct->digest)) {
> +	if (digest_size > sizeof(digest_struct->digest) ||
> +	    (!digest_size_ptr && digest_size != expected_digest_size)) {
>  		rc = -EINVAL;
>  		goto out;
>  	}
> -- 
> 2.17.1
> 

Please add

Cc: stable@vger.kernel.org.

/Jarkko
Roberto Sassu Nov. 8, 2018, 2:47 p.m. UTC | #2
On 11/8/2018 3:08 PM, Jarkko Sakkinen wrote:
> On Tue, Nov 06, 2018 at 04:01:59PM +0100, Roberto Sassu wrote:
>> This patch protects against data corruption that could happen in the bus,
>> by checking that that the digest size returned by the TPM during a PCR read
>> matches the size of the algorithm passed as argument to tpm2_pcr_read().
>>
>> This check is performed after information about the PCR banks has been
>> retrieved.
>>
>> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
>> ---
>>   drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++-
>>   1 file changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
>> index e2d5b84286a7..3b0b5b032901 100644
>> --- a/drivers/char/tpm/tpm2-cmd.c
>> +++ b/drivers/char/tpm/tpm2-cmd.c
>> @@ -187,15 +187,28 @@ struct tpm2_pcr_read_out {
>>   int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
>>   		  struct tpm_digest *digest_struct, u16 *digest_size_ptr)
>>   {
>> +	int i;
>>   	int rc;
>>   	struct tpm_buf buf;
>>   	struct tpm2_pcr_read_out *out;
>>   	u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
>>   	u16 digest_size;
>> +	u16 expected_digest_size = 0;
>>   
>>   	if (pcr_idx >= TPM2_PLATFORM_PCR)
>>   		return -EINVAL;
>>   
>> +	if (!digest_size_ptr) {
>> +		for (i = 0; i < chip->nr_active_banks &&
>> +		     chip->active_banks[i].alg_id != digest_struct->alg_id; i++)
>> +			;
> 
> Not sure if the semicolon should be in its own line.

scripts/Lindent suggests:

for (i = 0; i < chip->nr_active_banks &&
      chip->active_banks[i].alg_id != digest_struct->alg_id;
      i++) ;

but this is not accepted by scripts/checkpatch.pl (there are no
warnings/errors on the patch I sent).


>> +
>> +		if (i == chip->nr_active_banks)
>> +			return -EINVAL;
>> +
>> +		expected_digest_size = chip->active_banks[i].digest_size;
>> +	}
>> +
>>   	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
>>   	if (rc)
>>   		return rc;
>> @@ -215,7 +228,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
>>   
>>   	out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
>>   	digest_size = be16_to_cpu(out->digest_size);
>> -	if (digest_size > sizeof(digest_struct->digest)) {
>> +	if (digest_size > sizeof(digest_struct->digest) ||
>> +	    (!digest_size_ptr && digest_size != expected_digest_size)) {
>>   		rc = -EINVAL;
>>   		goto out;
>>   	}
>> -- 
>> 2.17.1
>>
> 
> Please add
> 
> Cc: stable@vger.kernel.org.
> 
> /Jarkko
>
Jarkko Sakkinen Nov. 8, 2018, 6:52 p.m. UTC | #3
On Thu, Nov 08, 2018 at 03:47:39PM +0100, Roberto Sassu wrote:
> > > +		for (i = 0; i < chip->nr_active_banks &&
> > > +		     chip->active_banks[i].alg_id != digest_struct->alg_id; i++)
> > > +			;
> > 
> > Not sure if the semicolon should be in its own line.
> 
> scripts/Lindent suggests:
> 
> for (i = 0; i < chip->nr_active_banks &&
>      chip->active_banks[i].alg_id != digest_struct->alg_id;
>      i++) ;
> 
> but this is not accepted by scripts/checkpatch.pl (there are no
> warnings/errors on the patch I sent).

Yeah, not a really blocker for me.

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

/Jarkko
Roberto Sassu Nov. 13, 2018, 1:08 p.m. UTC | #4
On 11/8/2018 3:08 PM, Jarkko Sakkinen wrote:
> On Tue, Nov 06, 2018 at 04:01:59PM +0100, Roberto Sassu wrote:
>> This patch protects against data corruption that could happen in the bus,
>> by checking that that the digest size returned by the TPM during a PCR read
>> matches the size of the algorithm passed as argument to tpm2_pcr_read().
>>
>> This check is performed after information about the PCR banks has been
>> retrieved.
>>
>> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
>> ---
>>   drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++-
>>   1 file changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
>> index e2d5b84286a7..3b0b5b032901 100644
>> --- a/drivers/char/tpm/tpm2-cmd.c
>> +++ b/drivers/char/tpm/tpm2-cmd.c
>> @@ -187,15 +187,28 @@ struct tpm2_pcr_read_out {
>>   int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
>>   		  struct tpm_digest *digest_struct, u16 *digest_size_ptr)
>>   {
>> +	int i;
>>   	int rc;
>>   	struct tpm_buf buf;
>>   	struct tpm2_pcr_read_out *out;
>>   	u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
>>   	u16 digest_size;
>> +	u16 expected_digest_size = 0;
>>   
>>   	if (pcr_idx >= TPM2_PLATFORM_PCR)
>>   		return -EINVAL;
>>   
>> +	if (!digest_size_ptr) {
>> +		for (i = 0; i < chip->nr_active_banks &&
>> +		     chip->active_banks[i].alg_id != digest_struct->alg_id; i++)
>> +			;
> 
> Not sure if the semicolon should be in its own line.
> `
>> +
>> +		if (i == chip->nr_active_banks)
>> +			return -EINVAL;
>> +
>> +		expected_digest_size = chip->active_banks[i].digest_size;
>> +	}
>> +
>>   	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
>>   	if (rc)
>>   		return rc;
>> @@ -215,7 +228,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
>>   
>>   	out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
>>   	digest_size = be16_to_cpu(out->digest_size);
>> -	if (digest_size > sizeof(digest_struct->digest)) {
>> +	if (digest_size > sizeof(digest_struct->digest) ||
>> +	    (!digest_size_ptr && digest_size != expected_digest_size)) {
>>   		rc = -EINVAL;
>>   		goto out;
>>   	}
>> -- 
>> 2.17.1
>>
> 
> Please add
> 
> Cc: stable@vger.kernel.org.

Should I do the same for the previous patches? This patch cannot be
applied alone.

Roberto


> /Jarkko
>
Jarkko Sakkinen Nov. 13, 2018, 4:59 p.m. UTC | #5
On Tue, Nov 13, 2018 at 02:08:39PM +0100, Roberto Sassu wrote:
> On 11/8/2018 3:08 PM, Jarkko Sakkinen wrote:
> > On Tue, Nov 06, 2018 at 04:01:59PM +0100, Roberto Sassu wrote:
> > > This patch protects against data corruption that could happen in the bus,
> > > by checking that that the digest size returned by the TPM during a PCR read
> > > matches the size of the algorithm passed as argument to tpm2_pcr_read().
> > > 
> > > This check is performed after information about the PCR banks has been
> > > retrieved.
> > > 
> > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > > ---
> > >   drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++-
> > >   1 file changed, 15 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> > > index e2d5b84286a7..3b0b5b032901 100644
> > > --- a/drivers/char/tpm/tpm2-cmd.c
> > > +++ b/drivers/char/tpm/tpm2-cmd.c
> > > @@ -187,15 +187,28 @@ struct tpm2_pcr_read_out {
> > >   int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
> > >   		  struct tpm_digest *digest_struct, u16 *digest_size_ptr)
> > >   {
> > > +	int i;
> > >   	int rc;
> > >   	struct tpm_buf buf;
> > >   	struct tpm2_pcr_read_out *out;
> > >   	u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
> > >   	u16 digest_size;
> > > +	u16 expected_digest_size = 0;
> > >   	if (pcr_idx >= TPM2_PLATFORM_PCR)
> > >   		return -EINVAL;
> > > +	if (!digest_size_ptr) {
> > > +		for (i = 0; i < chip->nr_active_banks &&
> > > +		     chip->active_banks[i].alg_id != digest_struct->alg_id; i++)
> > > +			;
> > 
> > Not sure if the semicolon should be in its own line.
> > `
> > > +
> > > +		if (i == chip->nr_active_banks)
> > > +			return -EINVAL;
> > > +
> > > +		expected_digest_size = chip->active_banks[i].digest_size;
> > > +	}
> > > +
> > >   	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
> > >   	if (rc)
> > >   		return rc;
> > > @@ -215,7 +228,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
> > >   	out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
> > >   	digest_size = be16_to_cpu(out->digest_size);
> > > -	if (digest_size > sizeof(digest_struct->digest)) {
> > > +	if (digest_size > sizeof(digest_struct->digest) ||
> > > +	    (!digest_size_ptr && digest_size != expected_digest_size)) {
> > >   		rc = -EINVAL;
> > >   		goto out;
> > >   	}
> > > -- 
> > > 2.17.1
> > > 
> > 
> > Please add
> > 
> > Cc: stable@vger.kernel.org.
> 
> Should I do the same for the previous patches? This patch cannot be
> applied alone.
> 
> Roberto

No need. It is an issue that we deal with depenendent commits once it is
being backported. This could be dependent for example of a commit that
is even not in the series so does not make sense to do it now.

/Jarkko

Patch
diff mbox series

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index e2d5b84286a7..3b0b5b032901 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -187,15 +187,28 @@  struct tpm2_pcr_read_out {
 int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
 		  struct tpm_digest *digest_struct, u16 *digest_size_ptr)
 {
+	int i;
 	int rc;
 	struct tpm_buf buf;
 	struct tpm2_pcr_read_out *out;
 	u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
 	u16 digest_size;
+	u16 expected_digest_size = 0;
 
 	if (pcr_idx >= TPM2_PLATFORM_PCR)
 		return -EINVAL;
 
+	if (!digest_size_ptr) {
+		for (i = 0; i < chip->nr_active_banks &&
+		     chip->active_banks[i].alg_id != digest_struct->alg_id; i++)
+			;
+
+		if (i == chip->nr_active_banks)
+			return -EINVAL;
+
+		expected_digest_size = chip->active_banks[i].digest_size;
+	}
+
 	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
 	if (rc)
 		return rc;
@@ -215,7 +228,8 @@  int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
 
 	out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
 	digest_size = be16_to_cpu(out->digest_size);
-	if (digest_size > sizeof(digest_struct->digest)) {
+	if (digest_size > sizeof(digest_struct->digest) ||
+	    (!digest_size_ptr && digest_size != expected_digest_size)) {
 		rc = -EINVAL;
 		goto out;
 	}