From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Subject: Re: [PATCH RFC] tpm: migrate pubek_show to struct tpm_buf Date: Thu, 25 May 2017 15:28:01 -0700 Message-ID: <20170525222801.mayost6gxcggurjo@intel.com> References: <20170525211105.843-1-jarkko.sakkinen@linux.intel.com> <20170525211613.GA14802@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170525211613.GA14802@obsidianresearch.com> Sender: owner-linux-security-module@vger.kernel.org To: Jason Gunthorpe Cc: tpmdd-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, Peter Huewe , Marcel Selhorst , open list List-Id: tpmdd-devel@lists.sourceforge.net On Thu, May 25, 2017 at 03:16:13PM -0600, Jason Gunthorpe wrote: > On Thu, May 25, 2017 at 02:11:04PM -0700, Jarkko Sakkinen wrote: > > struct tpm_chip *chip = to_tpm_chip(dev); > > + char anti_replay[20]; > > > > - tpm_cmd.header.in = tpm_readpubek_header; > > - err = tpm_transmit_cmd(chip, NULL, &tpm_cmd, READ_PUBEK_RESULT_SIZE, > > + rc = tpm_buf_init(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK); > > + if (rc) > > + return rc; > > + > > + /* The checksum is ignored so it doesn't matter what the contents are. > > + */ > > + tpm_buf_append(&tpm_buf, anti_replay, sizeof(anti_replay)); > > It does matter, we do not want to leak random kernel memory incase it > has something sensitive. Zero anti_replay. If there was a leak it has existed before this change as tpm_cmd was also allocated from stack. And there is not leak because the checksum is not printed. > > + > > - /* > > - ignore header 10 bytes > > - algorithm 32 bits (1 == RSA ) > > - encscheme 16 bits > > - sigscheme 16 bits > > - parameters (RSA 12->bytes: keybit, #primes, expbit) > > - keylenbytes 32 bits > > - 256 byte modulus > > - ignore checksum 20 bytes > > - */ > > Not sure we should delete the comment, tpm buf does not make the parse > any clearer. I think better idea would be to move struct tpm_readpubek_params_out declaration here and use it to refer different fields. Previously this has been a complete mess. The structure has been declared but it has not been used for anything. I wonder what is the history here... /Jarkko