From: Jason Gunthorpe <jgg@ziepe.ca>
To: Tadeusz Struk <tadeusz.struk@intel.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tpm: add support for partial reads
Date: Mon, 23 Jul 2018 15:56:20 -0600 [thread overview]
Message-ID: <20180723215620.GH532@ziepe.ca> (raw)
In-Reply-To: <7441b5ef-18d8-13aa-ef4d-40fe684c9218@intel.com>
On Mon, Jul 23, 2018 at 02:38:08PM -0700, Tadeusz Struk wrote:
> On 07/23/2018 02:13 PM, James Bottomley wrote:
> > The current patch does, you even provided a use case in your last email
> > (it's do command to get sizing followed by do command with correctly
> > sized buffer).
>
> The example I provided was: #1 send a command, #2 read the response header
> (10 bytes), get the actual response size from the header and then #3 read
> the full response (response size - size of the header bytes).
The proposed patch doesn't clear the data_pending if the entire buffer
is not consumed, so of course it is ABI breaking, that really isn't OK.
> > However, if you tie it to O_NONBLOCK, it won't because no-one currently
> > opens the TPM device non blocking so it's an ABI conformant
> > discriminator of the uses. Tying to O_NONBLOCK should be simple
> > because it's in file->f_flags.
>
> I think that it might be an option. Especially that I have this on top of
> the async patch. Let's discuss this when Jarkko is back.
Maybe you could do this by requiring the userspace to call pread()
with a non-zero offset to get the trailing segment of the last
executed command and leave normal read/pread(off=0) with the semantics
as they have today.
Jason
next prev parent reply other threads:[~2018-07-23 21:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-19 15:52 [PATCH] tpm: add support for partial reads Tadeusz Struk
2018-07-19 15:55 ` Tadeusz Struk
2018-07-19 17:19 ` James Bottomley
2018-07-19 17:54 ` Tadeusz Struk
2018-07-19 18:47 ` James Bottomley
2018-07-19 19:05 ` Tadeusz Struk
2018-07-19 19:52 ` James Bottomley
2018-07-19 20:12 ` Tadeusz Struk
2018-07-19 20:27 ` James Bottomley
2018-07-19 21:01 ` Tadeusz Struk
2018-07-23 20:19 ` Jarkko Sakkinen
2018-07-23 20:53 ` Tadeusz Struk
2018-07-23 21:13 ` James Bottomley
2018-07-23 21:38 ` Tadeusz Struk
2018-07-23 21:56 ` Jason Gunthorpe [this message]
2018-07-23 22:00 ` Tadeusz Struk
2018-07-23 22:08 ` Jason Gunthorpe
2018-07-23 23:42 ` Tadeusz Struk
2018-07-24 2:05 ` Jason Gunthorpe
2018-07-23 21:48 ` Jason Gunthorpe
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