From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Subject: Re: [PATCH v6 3/3] tpm: vtpm_proxy: Prevent userspace from sending driver command Date: Wed, 24 May 2017 17:10:49 -0700 Message-ID: <20170525001049.4e2zyxeihs3cvq2n@intel.com> References: <1495661981-27249-1-git-send-email-stefanb@linux.vnet.ibm.com> <1495661981-27249-4-git-send-email-stefanb@linux.vnet.ibm.com> <20170524222211.bweuzimsy2vm2lym@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20170524222211.bweuzimsy2vm2lym-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tpmdd-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Stefan Berger Cc: linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: tpmdd-devel@lists.sourceforge.net On Wed, May 24, 2017 at 03:22:11PM -0700, Jarkko Sakkinen wrote: > On Wed, May 24, 2017 at 05:39:41PM -0400, Stefan Berger wrote: > > To prevent userspace from sending the TPM driver command to set > > the locality, we need to check every command that is sent from > > user space. To distinguish user space commands from internally > > sent commands we introduce an additional state flag > > STATE_DRIVER_COMMAND that is set while the driver sends this > > command. Similar to the TPM 2 space commands we return an error > > code when this command is detected. > > > > Signed-off-by: Stefan Berger > > --- > > drivers/char/tpm/tpm_vtpm_proxy.c | 33 +++++++++++++++++++++++++++++++++ > > 1 file changed, 33 insertions(+) > > > > diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c > > index 66024bf..1d877cc 100644 > > --- a/drivers/char/tpm/tpm_vtpm_proxy.c > > +++ b/drivers/char/tpm/tpm_vtpm_proxy.c > > @@ -43,6 +43,7 @@ struct proxy_dev { > > #define STATE_OPENED_FLAG BIT(0) > > #define STATE_WAIT_RESPONSE_FLAG BIT(1) /* waiting for emulator response */ > > #define STATE_REGISTERED_FLAG BIT(2) > > +#define STATE_DRIVER_COMMAND BIT(3) /* sending a driver specific command */ > > > > size_t req_len; /* length of queued TPM request */ > > size_t resp_len; /* length of queued TPM response */ > > @@ -299,6 +300,28 @@ static int vtpm_proxy_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count) > > return len; > > } > > > > +static int vtpm_proxy_is_driver_command(struct tpm_chip *chip, > > + u8 *buf, size_t count) > > +{ > > + struct tpm_input_header *hdr = (struct tpm_input_header *)buf; > > + > > + if (count < sizeof(struct tpm_input_header)) > > + return 0; > > + > > + if (chip->flags & TPM_CHIP_FLAG_TPM2) { > > + switch (be32_to_cpu(hdr->ordinal)) { > > + case TPM2_CC_SET_LOCALITY: > > + return 1; > > + } > > + } else { > > + switch (be32_to_cpu(hdr->ordinal)) { > > + case TPM_ORD_SET_LOCALITY: > > + return 1; > > + } > > + } > > + return 0; > > +} > > + > > /* > > * Called when core TPM driver forwards TPM requests to 'server side'. > > * > > @@ -321,6 +344,10 @@ static int vtpm_proxy_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t count) > > return -EIO; > > } > > > > + if (!(proxy_dev->state & STATE_DRIVER_COMMAND) && > > + vtpm_proxy_is_driver_command(chip, buf, count)) > > + return -EFAULT; > > + > > mutex_lock(&proxy_dev->buf_lock); > > > > if (!(proxy_dev->state & STATE_OPENED_FLAG)) { > > @@ -376,6 +403,7 @@ static int vtpm_proxy_request_locality(struct tpm_chip *chip, int locality) > > struct tpm_buf buf; > > int rc; > > const struct tpm_output_header *header; > > + struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev); > > > > if (chip->flags & TPM_CHIP_FLAG_TPM2) > > rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, > > @@ -387,9 +415,14 @@ static int vtpm_proxy_request_locality(struct tpm_chip *chip, int locality) > > return rc; > > tpm_buf_append_u8(&buf, locality); > > > > + proxy_dev->state |= STATE_DRIVER_COMMAND; > > + > > rc = tpm_transmit_cmd(chip, NULL, buf.data, tpm_buf_length(&buf), 0, > > TPM_TRANSMIT_UNLOCKED | TPM_TRANSMIT_RAW, > > "attempting to set locality"); > > + > > + proxy_dev->state &= ~STATE_DRIVER_COMMAND; > > + > > if (rc < 0) { > > locality = rc; > > goto out; > > -- > > 2.4.3 > > > > Otherwise fine except for the redundant code. > > /Jarkko Reviewed-by: Jarkko Sakkinen Probably not yet merging and testing this this week though as I'm travelling in US right now. /Jarkko ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot