* [PATCH] x86/sgx: Fix ELDU MAC failures
@ 2019-08-23 2:00 Sean Christopherson
2019-08-23 13:35 ` Jarkko Sakkinen
0 siblings, 1 reply; 4+ messages in thread
From: Sean Christopherson @ 2019-08-23 2:00 UTC (permalink / raw)
To: Jarkko Sakkinen; +Cc: linux-sgx
Revert a change that directly propagates the page type from SECINFO into
encl_page->desc. encl_page->desc is a packed value, jamming the SECINFO
page_type sets bits that are intended for other uses.
Specifically, bits 11:3 are used to store the VA offset when a page is
swapped out and are available for other uses when the page is resident
in the EPC. To allow overloading bits 11:3, the VA offset is cleared at
ELDU and so is not explicitly cleared at EWB, e.g. the VA offset is OR'd
into encl_page->desc. As a result, a subsequent ELDU gets a MAC failure
due to loading the wrong VA offset.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kernel/cpu/sgx/driver/ioctl.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
index 85e36e530baf..355ce967a77f 100644
--- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
@@ -140,7 +140,8 @@ static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
return ERR_PTR(-ENOMEM);
encl_page->desc = addr;
- encl_page->desc |= page_type;
+ if (page_type == SGX_SECINFO_TCS)
+ encl_page->desc |= SGX_ENCL_PAGE_TCS;
encl_page->encl = encl;
/* Calculate maximum of the VM flags for the page. */
--
2.22.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] x86/sgx: Fix ELDU MAC failures
2019-08-23 2:00 [PATCH] x86/sgx: Fix ELDU MAC failures Sean Christopherson
@ 2019-08-23 13:35 ` Jarkko Sakkinen
2019-08-23 13:39 ` Jarkko Sakkinen
0 siblings, 1 reply; 4+ messages in thread
From: Jarkko Sakkinen @ 2019-08-23 13:35 UTC (permalink / raw)
To: Sean Christopherson; +Cc: linux-sgx, luto
On Thu, 2019-08-22 at 19:00 -0700, Sean Christopherson wrote:
> Revert a change that directly propagates the page type from SECINFO into
> encl_page->desc. encl_page->desc is a packed value, jamming the SECINFO
> page_type sets bits that are intended for other uses.
>
> Specifically, bits 11:3 are used to store the VA offset when a page is
> swapped out and are available for other uses when the page is resident
> in the EPC. To allow overloading bits 11:3, the VA offset is cleared at
> ELDU and so is not explicitly cleared at EWB, e.g. the VA offset is OR'd
> into encl_page->desc. As a result, a subsequent ELDU gets a MAC failure
> due to loading the wrong VA offset.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/kernel/cpu/sgx/driver/ioctl.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> index 85e36e530baf..355ce967a77f 100644
> --- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> @@ -140,7 +140,8 @@ static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
> return ERR_PTR(-ENOMEM);
>
> encl_page->desc = addr;
> - encl_page->desc |= page_type;
> + if (page_type == SGX_SECINFO_TCS)
> + encl_page->desc |= SGX_ENCL_PAGE_TCS;
> encl_page->encl = encl;
Oops. How embrassing from my side. Please also ignore my original review
comment about unreadability. The parameter type was right and everything
was right. I was just blind for a while.
This is exactly how it should be e.g. no boolean parameter. I think with
most of this kind of APIs we should follow a patttern the API takes PT
and the function does whatever encoding we have.
/Jarkko
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86/sgx: Fix ELDU MAC failures
2019-08-23 13:35 ` Jarkko Sakkinen
@ 2019-08-23 13:39 ` Jarkko Sakkinen
2019-08-23 13:54 ` Jarkko Sakkinen
0 siblings, 1 reply; 4+ messages in thread
From: Jarkko Sakkinen @ 2019-08-23 13:39 UTC (permalink / raw)
To: Sean Christopherson; +Cc: linux-sgx, luto
On Fri, 2019-08-23 at 16:35 +0300, Jarkko Sakkinen wrote:
> On Thu, 2019-08-22 at 19:00 -0700, Sean Christopherson wrote:
> > Revert a change that directly propagates the page type from SECINFO into
> > encl_page->desc. encl_page->desc is a packed value, jamming the SECINFO
> > page_type sets bits that are intended for other uses.
> >
> > Specifically, bits 11:3 are used to store the VA offset when a page is
> > swapped out and are available for other uses when the page is resident
> > in the EPC. To allow overloading bits 11:3, the VA offset is cleared at
> > ELDU and so is not explicitly cleared at EWB, e.g. the VA offset is OR'd
> > into encl_page->desc. As a result, a subsequent ELDU gets a MAC failure
> > due to loading the wrong VA offset.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > ---
> > arch/x86/kernel/cpu/sgx/driver/ioctl.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> > index 85e36e530baf..355ce967a77f 100644
> > --- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> > +++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> > @@ -140,7 +140,8 @@ static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
> > return ERR_PTR(-ENOMEM);
> >
> > encl_page->desc = addr;
> > - encl_page->desc |= page_type;
> > + if (page_type == SGX_SECINFO_TCS)
> > + encl_page->desc |= SGX_ENCL_PAGE_TCS;
> > encl_page->encl = encl;
>
> Oops. How embrassing from my side. Please also ignore my original review
> comment about unreadability. The parameter type was right and everything
> was right. I was just blind for a while.
>
> This is exactly how it should be e.g. no boolean parameter. I think with
> most of this kind of APIs we should follow a patttern the API takes PT
> and the function does whatever encoding we have.
In any case the issue is fixed now on my tree and I also rewrote commit
message for the driver.
/Jarkko
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86/sgx: Fix ELDU MAC failures
2019-08-23 13:39 ` Jarkko Sakkinen
@ 2019-08-23 13:54 ` Jarkko Sakkinen
0 siblings, 0 replies; 4+ messages in thread
From: Jarkko Sakkinen @ 2019-08-23 13:54 UTC (permalink / raw)
To: Sean Christopherson; +Cc: linux-sgx, luto
On Fri, 2019-08-23 at 16:39 +0300, Jarkko Sakkinen wrote:
> On Fri, 2019-08-23 at 16:35 +0300, Jarkko Sakkinen wrote:
> > On Thu, 2019-08-22 at 19:00 -0700, Sean Christopherson wrote:
> > > Revert a change that directly propagates the page type from SECINFO into
> > > encl_page->desc. encl_page->desc is a packed value, jamming the SECINFO
> > > page_type sets bits that are intended for other uses.
> > >
> > > Specifically, bits 11:3 are used to store the VA offset when a page is
> > > swapped out and are available for other uses when the page is resident
> > > in the EPC. To allow overloading bits 11:3, the VA offset is cleared at
> > > ELDU and so is not explicitly cleared at EWB, e.g. the VA offset is OR'd
> > > into encl_page->desc. As a result, a subsequent ELDU gets a MAC failure
> > > due to loading the wrong VA offset.
> > >
> > > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > > ---
> > > arch/x86/kernel/cpu/sgx/driver/ioctl.c | 3 ++-
> > > 1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> > > index 85e36e530baf..355ce967a77f 100644
> > > --- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> > > +++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> > > @@ -140,7 +140,8 @@ static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
> > > return ERR_PTR(-ENOMEM);
> > >
> > > encl_page->desc = addr;
> > > - encl_page->desc |= page_type;
> > > + if (page_type == SGX_SECINFO_TCS)
> > > + encl_page->desc |= SGX_ENCL_PAGE_TCS;
> > > encl_page->encl = encl;
> >
> > Oops. How embrassing from my side. Please also ignore my original review
> > comment about unreadability. The parameter type was right and everything
> > was right. I was just blind for a while.
> >
> > This is exactly how it should be e.g. no boolean parameter. I think with
> > most of this kind of APIs we should follow a patttern the API takes PT
> > and the function does whatever encoding we have.
>
> In any case the issue is fixed now on my tree and I also rewrote commit
> message for the driver.
The stress test that I've been using is temporarily broken ATM so could not
exercise the code path.
/Jarkko
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-08-23 2:00 [PATCH] x86/sgx: Fix ELDU MAC failures Sean Christopherson
2019-08-23 13:35 ` Jarkko Sakkinen
2019-08-23 13:39 ` Jarkko Sakkinen
2019-08-23 13:54 ` Jarkko Sakkinen
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