Re: [tpmdd-devel] [PATCH RFC v3 5/5] tpm2: expose resource manager via a device link /dev/tpms<n>

[Jarkko Sakkinen]

On Sat, Jan 21, 2017 at 11:28:55AM -0800, James Bottomley wrote:
> On Fri, 2017-01-20 at 23:05 +0200, Jarkko Sakkinen wrote:
> > On Fri, Jan 20, 2017 at 03:39:14PM +0200, Jarkko Sakkinen wrote:
> > > On Thu, Jan 19, 2017 at 07:19:40AM -0500, James Bottomley wrote:
> > > > On Thu, 2017-01-19 at 12:49 +0200, Jarkko Sakkinen wrote:
> > > > > On Wed, Jan 18, 2017 at 10:01:03AM -0500, James Bottomley
> > > > > wrote:
> > > > > > On Mon, 2017-01-16 at 15:12 +0200, Jarkko Sakkinen wrote:
> > > > > > > From: James Bottomley <
> > > > > > > James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> > > > > > > 
> > > > > > > Currently the Resource Manager (RM) is not exposed to
> > > > > > > userspace. 
> > > > > > >  Make this exposure via a separate device, which can now be
> > > > > > > opened multiple times because each read/write transaction
> > > > > > > goes 
> > > > > > > separately via the RM.
> > > > > > > 
> > > > > > > Concurrency is protected by the chip->tpm_mutex for each 
> > > > > > > read/write transaction separately.  The TPM is cleared of
> > > > > > > all 
> > > > > > > transient objects by the time the mutex is dropped, so
> > > > > > > there 
> > > > > > > should be no interference between the kernel and userspace.
> > > > > > 
> > > > > > There's actually a missing kfree of context_buf on the
> > > > > > tpms_release
> > > > > > path as well.  This patch fixes it up.
> > > > > 
> > > > > Can you send me a fresh version of the whole patch so that I
> > > > > can 
> > > > > include to v4 that includes also changes that I requested in my
> > > > > recent comments + all the fixes?
> > > > 
> > > > Sure, I think the attached is basically it
> > > > 
> > > > James
> > > 
> > > Thank you!
> > 
> > 'tabrm4' branch has been now rebased. It's now on top of master
> > branch
> > that contains Stefan's latest patch (min body length check) that I've
> > reviewed and tested. It also contains your updated /dev/tpms patch.
> > 
> > I guess the 5 commits that are there now are such that we have fairly
> > good consensus, don't we? If so, can I add your reviewed-by and
> > tested-by to my commits and vice versa?
> 
> Did you actually test it?  It doesn't work for me.  The bisected fault
> commit is this one (newly introduced into the tabrm4 branch)
> 
> commit 9b7f4252655228c8d0b86e1492cc7fb3feaa5686
> Author: Stefan Berger <stefanb@xxxxxxxxxxxxxxxxxx>
> Date:   Thu Jan 19 07:19:12 2017 -0500
> 
>     tpm: Check size of response before accessing data
>  
> The specific problem is that our min_rsp_length in
> tpm_{load,save}_context includes a header size and the check this
> introduces does the check is against the body size, meaning the load
> fails because tpm_transmit_cmd thinks the response is too short.
> 
> The patch to fix this is below.
> 
> James

I noticed the same thing last night. Sorry about that. It's now been
fixed. I did test it but somehow what went to my remote tree does not
have matching contents so I screwed something up at some point.

/Jarkko

> 
> ---
> commit 480f2bb484f5a7e6100c6b0d1c79f72a05a0ca88
> Author: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> Date:   Sat Jan 21 11:26:24 2017 -0800
> 
>     fix tpm_transmit_cmd min response size problem
> 
> diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
> index 4b5c714..3237d7c 100644
> --- a/drivers/char/tpm/tpm2-space.c
> +++ b/drivers/char/tpm/tpm2-space.c
> @@ -53,7 +53,7 @@ static int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
>  	tpm_buf_append(&tbuf, &buf[*offset], body_size);
>  
>  	rc = tpm_transmit_cmd(chip, NULL, tbuf.data, PAGE_SIZE,
> -			      TPM_HEADER_SIZE + 4, TPM_TRANSMIT_UNLOCKED, "load context");
> +			      4, TPM_TRANSMIT_UNLOCKED, "load context");
>  	if ((rc & TPM2_RC_HANDLE) == TPM2_RC_HANDLE) {
>  		rc = -ENOENT;
>  		tpm_buf_destroy(&tbuf);
> @@ -89,7 +89,7 @@ static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf,
>  
>  	tpm_buf_append_u32(&tbuf, handle);
>  
> -	rc = tpm_transmit_cmd(chip, NULL, tbuf.data, PAGE_SIZE, TPM_HEADER_SIZE,
> +	rc = tpm_transmit_cmd(chip, NULL, tbuf.data, PAGE_SIZE, 0,
>  			      TPM_TRANSMIT_UNLOCKED, NULL);
>  	if (rc < 0) {
>  		dev_warn(&chip->dev, "%s: saving failed with a system error %d\n",
> 
> 
>