Re: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
On Wed, Feb 06, 2019 at 12:55:55PM +, Winkler, Tomas wrote: > > Fixed comments and applied the patch, thank you. Do I amend your acked-by? > > Please, do. > Thanks > Tomas Great, thank you. /Jarkko
RE: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
()
>
> On Tue, Feb 05, 2019 at 10:57:19PM +0200, Jarkko Sakkinen wrote:
> > On Tue, Feb 05, 2019 at 02:56:02PM +, Winkler, Tomas wrote:
> > >
> > >
> > > > -Original Message-
> > > > From: Jarkko Sakkinen [mailto:jarkko.sakki...@linux.intel.com]
> > > > Sent: Tuesday, February 05, 2019 16:36
> > > > To: Winkler, Tomas
> > > > Cc: linux-integr...@vger.kernel.org; linux-kernel@vger.kernel.org;
> > > > linux- security-mod...@vger.kernel.org; sta...@vger.kernel.org;
> > > > James Morris ; Jerry Snitselaar
> > > >
> > > > Subject: Re: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in
> > > > crb_recv()
> > > >
> > > > On Tue, Feb 05, 2019 at 11:07:16AM +, Winkler, Tomas wrote:
> > > > > > The current approach to read first 6 bytes from the response
> > > > > > and then tail of the response, can cause the 2nd
> > > > > > memcpy_fromio() to do an unaligned read (e.g. read 32-bit word
> > > > > > from address aligned to a 16-bits), depending on how
> > > > > > memcpy_fromio() is implemented. If this happens, the read will
> > > > > > fail and the memory controller will fill the read with 1's.
> > > > > >
> > > > > > This was triggered by 170d13ca3a2f, which should be probably
> > > > > > refined to check and react to the address alignment. Before
> > > > > > that commit, on
> > > > > > x86
> > > > > > memcpy_fromio() turned out to be memcpy(). By a luck GCC has
> > > > > > done the right thing (from tpm_crb's perspective) for us so
> > > > > > far, but we should not
> > > > rely on that.
> > > > > > Thus, it makes sense to fix this also in tpm_crb, not least
> > > > > > because the fix can be then backported to stable kernels and
> > > > > > make them more robust when compiled in differing environments.
> > > > > >
> > > > > > Cc: sta...@vger.kernel.org
> > > > > > Cc: James Morris
> > > > > > Cc: Tomas Winkler
> > > > > > Cc: Jerry Snitselaar
> > > > > > Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface")
> > > > > > Signed-off-by: Jarkko Sakkinen
> > > > > >
> > > > > > Reviewed-by: Jerry Snitselaar
> > > > > > ---
> > > > > > v3:
> > > > > > * Fix typo i.e. %s/reminding/remaining/g
> > > > >
> > > > > Why you haven't fixed all the typos I've pointed out? I think you
> > > > > missed
> that.
> > > >
> > > > I saw only comment about remaining. Was there something else? Can fix.
> > >
> > > https://www.spinics.net/lists/stable/msg283648.html
> > >
> > > 1. unrecovable -> unrecoverable
> > > 2. /* Read 8 bytes (not just 6 bytes, which would cover the tag and
> > > the response length
> > > > +* fields) in order to make sure that the remaining memory
> > > > +accesses */
> >
> > Thanks and apologies for missing these.
>
> Fixed comments and applied the patch, thank you. Do I amend your acked-by?
Please, do.
Thanks
Tomas
Re: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
On Tue, Feb 05, 2019 at 10:57:19PM +0200, Jarkko Sakkinen wrote:
> On Tue, Feb 05, 2019 at 02:56:02PM +, Winkler, Tomas wrote:
> >
> >
> > > -Original Message-
> > > From: Jarkko Sakkinen [mailto:jarkko.sakki...@linux.intel.com]
> > > Sent: Tuesday, February 05, 2019 16:36
> > > To: Winkler, Tomas
> > > Cc: linux-integr...@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
> > > security-mod...@vger.kernel.org; sta...@vger.kernel.org; James Morris
> > > ; Jerry Snitselaar
> > > Subject: Re: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
> > >
> > > On Tue, Feb 05, 2019 at 11:07:16AM +, Winkler, Tomas wrote:
> > > > > The current approach to read first 6 bytes from the response and
> > > > > then tail of the response, can cause the 2nd memcpy_fromio() to do
> > > > > an unaligned read (e.g. read 32-bit word from address aligned to a
> > > > > 16-bits), depending on how
> > > > > memcpy_fromio() is implemented. If this happens, the read will fail
> > > > > and the memory controller will fill the read with 1's.
> > > > >
> > > > > This was triggered by 170d13ca3a2f, which should be probably refined
> > > > > to check and react to the address alignment. Before that commit, on
> > > > > x86
> > > > > memcpy_fromio() turned out to be memcpy(). By a luck GCC has done
> > > > > the right thing (from tpm_crb's perspective) for us so far, but we
> > > > > should not
> > > rely on that.
> > > > > Thus, it makes sense to fix this also in tpm_crb, not least because
> > > > > the fix can be then backported to stable kernels and make them more
> > > > > robust when compiled in differing environments.
> > > > >
> > > > > Cc: sta...@vger.kernel.org
> > > > > Cc: James Morris
> > > > > Cc: Tomas Winkler
> > > > > Cc: Jerry Snitselaar
> > > > > Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface")
> > > > > Signed-off-by: Jarkko Sakkinen
> > > > > Reviewed-by: Jerry Snitselaar
> > > > > ---
> > > > > v3:
> > > > > * Fix typo i.e. %s/reminding/remaining/g
> > > >
> > > > Why you haven't fixed all the typos I've pointed out? I think you
> > > > missed that.
> > >
> > > I saw only comment about remaining. Was there something else? Can fix.
> >
> > https://www.spinics.net/lists/stable/msg283648.html
> >
> > 1. unrecovable -> unrecoverable
> > 2. /* Read 8 bytes (not just 6 bytes, which would cover the tag and the
> > response length
> > > + * fields) in order to make sure that the remaining memory accesses */
>
> Thanks and apologies for missing these.
Fixed comments and applied the patch, thank you. Do I amend your
acked-by?
/Jarkko
Re: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
On Tue, Feb 05, 2019 at 02:56:02PM +, Winkler, Tomas wrote:
>
>
> > -Original Message-
> > From: Jarkko Sakkinen [mailto:jarkko.sakki...@linux.intel.com]
> > Sent: Tuesday, February 05, 2019 16:36
> > To: Winkler, Tomas
> > Cc: linux-integr...@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
> > security-mod...@vger.kernel.org; sta...@vger.kernel.org; James Morris
> > ; Jerry Snitselaar
> > Subject: Re: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
> >
> > On Tue, Feb 05, 2019 at 11:07:16AM +, Winkler, Tomas wrote:
> > > > The current approach to read first 6 bytes from the response and
> > > > then tail of the response, can cause the 2nd memcpy_fromio() to do
> > > > an unaligned read (e.g. read 32-bit word from address aligned to a
> > > > 16-bits), depending on how
> > > > memcpy_fromio() is implemented. If this happens, the read will fail
> > > > and the memory controller will fill the read with 1's.
> > > >
> > > > This was triggered by 170d13ca3a2f, which should be probably refined
> > > > to check and react to the address alignment. Before that commit, on
> > > > x86
> > > > memcpy_fromio() turned out to be memcpy(). By a luck GCC has done
> > > > the right thing (from tpm_crb's perspective) for us so far, but we
> > > > should not
> > rely on that.
> > > > Thus, it makes sense to fix this also in tpm_crb, not least because
> > > > the fix can be then backported to stable kernels and make them more
> > > > robust when compiled in differing environments.
> > > >
> > > > Cc: sta...@vger.kernel.org
> > > > Cc: James Morris
> > > > Cc: Tomas Winkler
> > > > Cc: Jerry Snitselaar
> > > > Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface")
> > > > Signed-off-by: Jarkko Sakkinen
> > > > Reviewed-by: Jerry Snitselaar
> > > > ---
> > > > v3:
> > > > * Fix typo i.e. %s/reminding/remaining/g
> > >
> > > Why you haven't fixed all the typos I've pointed out? I think you missed
> > > that.
> >
> > I saw only comment about remaining. Was there something else? Can fix.
>
> https://www.spinics.net/lists/stable/msg283648.html
>
> 1. unrecovable -> unrecoverable
> 2. /* Read 8 bytes (not just 6 bytes, which would cover the tag and the
> response length
> > +* fields) in order to make sure that the remaining memory accesses */
Thanks and apologies for missing these.
/Jarkko
RE: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
> -Original Message-
> From: Jarkko Sakkinen [mailto:jarkko.sakki...@linux.intel.com]
> Sent: Tuesday, February 05, 2019 16:36
> To: Winkler, Tomas
> Cc: linux-integr...@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
> security-mod...@vger.kernel.org; sta...@vger.kernel.org; James Morris
> ; Jerry Snitselaar
> Subject: Re: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
>
> On Tue, Feb 05, 2019 at 11:07:16AM +, Winkler, Tomas wrote:
> > > The current approach to read first 6 bytes from the response and
> > > then tail of the response, can cause the 2nd memcpy_fromio() to do
> > > an unaligned read (e.g. read 32-bit word from address aligned to a
> > > 16-bits), depending on how
> > > memcpy_fromio() is implemented. If this happens, the read will fail
> > > and the memory controller will fill the read with 1's.
> > >
> > > This was triggered by 170d13ca3a2f, which should be probably refined
> > > to check and react to the address alignment. Before that commit, on
> > > x86
> > > memcpy_fromio() turned out to be memcpy(). By a luck GCC has done
> > > the right thing (from tpm_crb's perspective) for us so far, but we should
> > > not
> rely on that.
> > > Thus, it makes sense to fix this also in tpm_crb, not least because
> > > the fix can be then backported to stable kernels and make them more
> > > robust when compiled in differing environments.
> > >
> > > Cc: sta...@vger.kernel.org
> > > Cc: James Morris
> > > Cc: Tomas Winkler
> > > Cc: Jerry Snitselaar
> > > Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface")
> > > Signed-off-by: Jarkko Sakkinen
> > > Reviewed-by: Jerry Snitselaar
> > > ---
> > > v3:
> > > * Fix typo i.e. %s/reminding/remaining/g
> >
> > Why you haven't fixed all the typos I've pointed out? I think you missed
> > that.
>
> I saw only comment about remaining. Was there something else? Can fix.
https://www.spinics.net/lists/stable/msg283648.html
1. unrecovable -> unrecoverable
2. /* Read 8 bytes (not just 6 bytes, which would cover the tag and the
response length
> + * fields) in order to make sure that the remaining memory accesses */
Thanks
Tomas
Re: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
On Tue, Feb 05, 2019 at 11:07:16AM +, Winkler, Tomas wrote:
> > The current approach to read first 6 bytes from the response and then tail
> > of
> > the response, can cause the 2nd memcpy_fromio() to do an unaligned read
> > (e.g. read 32-bit word from address aligned to a 16-bits), depending on how
> > memcpy_fromio() is implemented. If this happens, the read will fail and the
> > memory controller will fill the read with 1's.
> >
> > This was triggered by 170d13ca3a2f, which should be probably refined to
> > check
> > and react to the address alignment. Before that commit, on x86
> > memcpy_fromio() turned out to be memcpy(). By a luck GCC has done the right
> > thing (from tpm_crb's perspective) for us so far, but we should not rely on
> > that.
> > Thus, it makes sense to fix this also in tpm_crb, not least because the fix
> > can be
> > then backported to stable kernels and make them more robust when compiled
> > in differing environments.
> >
> > Cc: sta...@vger.kernel.org
> > Cc: James Morris
> > Cc: Tomas Winkler
> > Cc: Jerry Snitselaar
> > Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface")
> > Signed-off-by: Jarkko Sakkinen
> > Reviewed-by: Jerry Snitselaar
> > ---
> > v3:
> > * Fix typo i.e. %s/reminding/remaining/g
>
> Why you haven't fixed all the typos I've pointed out? I think you missed that.
I saw only comment about remaining. Was there something else? Can fix.
/Jarkko
RE: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv()
> The current approach to read first 6 bytes from the response and then tail of
> the response, can cause the 2nd memcpy_fromio() to do an unaligned read
> (e.g. read 32-bit word from address aligned to a 16-bits), depending on how
> memcpy_fromio() is implemented. If this happens, the read will fail and the
> memory controller will fill the read with 1's.
>
> This was triggered by 170d13ca3a2f, which should be probably refined to check
> and react to the address alignment. Before that commit, on x86
> memcpy_fromio() turned out to be memcpy(). By a luck GCC has done the right
> thing (from tpm_crb's perspective) for us so far, but we should not rely on
> that.
> Thus, it makes sense to fix this also in tpm_crb, not least because the fix
> can be
> then backported to stable kernels and make them more robust when compiled
> in differing environments.
>
> Cc: sta...@vger.kernel.org
> Cc: James Morris
> Cc: Tomas Winkler
> Cc: Jerry Snitselaar
> Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface")
> Signed-off-by: Jarkko Sakkinen
> Reviewed-by: Jerry Snitselaar
> ---
> v3:
> * Fix typo i.e. %s/reminding/remaining/g
Why you haven't fixed all the typos I've pointed out? I think you missed that.
Tomas
> v2:
> * There was a trailing double colon in the end of the short summary.
> * Check requested and expected length against TPM_HEADER_SIZE.
> * Add some explanatory comments to crb_recv().
> drivers/char/tpm/tpm_crb.c | 22 --
> 1 file changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index
> 36952ef98f90..ee4df7815912 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -287,19 +287,29 @@ static int crb_recv(struct tpm_chip *chip, u8 *buf,
> size_t count)
> struct crb_priv *priv = dev_get_drvdata(>dev);
> unsigned int expected;
>
> - /* sanity check */
> - if (count < 6)
> + /* A sanity check that the upper layer wants to get at least the header
> + * as that is the minimum size for any TPM response.
> + */
> + if (count < TPM_HEADER_SIZE)
> return -EIO;
>
> + /* If this bit is set, according to the spec, the TPM is in unrecovable
> + * condition.
> + */
> if (ioread32(>regs_t->ctrl_sts) & CRB_CTRL_STS_ERROR)
> return -EIO;
>
> - memcpy_fromio(buf, priv->rsp, 6);
> - expected = be32_to_cpup((__be32 *) [2]);
> - if (expected > count || expected < 6)
> + /* Read 8 bytes (not just 6 bytes, which would cover the response
> length
> + * field) in order to make sure that the remaining memory accesses
> will
> + * be aligned.
> + */
> + memcpy_fromio(buf, priv->rsp, 8);
> +
> + expected = be32_to_cpup((__be32 *)[2]);
> + if (expected > count || expected < TPM_HEADER_SIZE)
> return -EIO;
>
> - memcpy_fromio([6], >rsp[6], expected - 6);
> + memcpy_fromio([8], >rsp[8], expected - 8);
>
> return expected;
> }
> --
> 2.19.1
