From: Daniel Kiper <daniel.kiper@oracle.com>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: linux-doc@vger.kernel.org, dpsmith@apertussolutions.com,
Ross Philipson <ross.philipson@oracle.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
luto@amacapital.net, iommu@lists.linux-foundation.org,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
linux-integrity@vger.kernel.org,
trenchboot-devel@googlegroups.com, tglx@linutronix.de
Subject: Re: [PATCH 07/13] x86: Secure Launch kernel early boot stub
Date: Thu, 15 Oct 2020 20:26:54 +0200 [thread overview]
Message-ID: <20201015182654.lgtht5fd2aaunczu@tomti.i.net-space.pl> (raw)
In-Reply-To: <d34c189c-4528-0458-0b84-cfd36dc068b3@oracle.com>
On Tue, Sep 29, 2020 at 10:03:47AM -0400, Ross Philipson wrote:
> On 9/25/20 3:18 PM, Arvind Sankar wrote:
[...]
> > You should see them if you do
> > readelf -r arch/x86/boot/compressed/vmlinux
> >
> > In terms of the code, things like:
> >
> > addl %ebx, (sl_gdt_desc + 2)(%ebx)
> >
> > will create a relocation, because the linker interprets this as wanting
> > the runtime address of sl_gdt_desc, rather than just the offset from
> > startup_32.
> >
> > https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/tree/arch/x86/boot/compressed/head_64.S*n48__;Iw!!GqivPVa7Brio!JpZWv1cCPZdjD2jbCCGT7P9UIVl_lhX7YjckAnUcvi927jwZI7X3nX0MpIAZOyktJds$
> >
> > has a comment with some explanation and a macro that the 32-bit code in
> > startup_32 uses to avoid creating relocations.
> >
> > Since the SL code is in a different assembler file (and a different
> > section), you can't directly use the same macro. I would suggest getting
> > rid of sl_stub_entry and entering directly at sl_stub, and then the code
> > in sl_stub.S can use sl_stub for the base address, defining the rva()
> > macro there as
> >
> > #define rva(X) ((X) - sl_stub)
> >
> > You will also need to avoid initializing data with symbol addresses.
> >
> > .long mle_header
> > .long sl_stub_entry
> > .long sl_gdt
> >
> > will create relocations. The third one is easy, just replace it with
> > sl_gdt - sl_gdt_desc and initialize it at runtime with
> >
> > leal rva(sl_gdt_desc)(%ebx), %eax
> > addl %eax, 2(%eax)
> > lgdt (%eax)
> >
> > The other two are more messy, unfortunately there is no easy way to tell
> > the linker what we want here. The other entry point addresses (for the
> > EFI stub) are populated in a post-processing step after the compressed
> > kernel has been linked, we could teach it to also update kernel_info.
> >
> > Without that, for kernel_info, you could change it to store the offset
> > of the MLE header from kernel_info, instead of from the start of the
> > image.
> >
> > For the MLE header, it could be moved to .head.text in head_64.S, and
> > initialized with
> > .long rva(sl_stub)
> > This will also let it be placed at a fixed offset from startup_32, so
> > that kernel_info can just be populated with a constant.
I am discussing with Ross the other option. We can create
.rodata.mle_header section and put it at fixed offset as
kernel_info is. So, we would have, e.g.:
arch/x86/boot/compressed/vmlinux.lds.S:
.rodata.kernel_info KERNEL_INFO_OFFSET : {
*(.rodata.kernel_info)
}
ASSERT(ABSOLUTE(kernel_info) == KERNEL_INFO_OFFSET, "kernel_info at bad address!")
.rodata.mle_header MLE_HEADER_OFFSET : {
*(.rodata.mle_header)
}
ASSERT(ABSOLUTE(mle_header) == MLE_HEADER_OFFSET, "mle_header at bad address!")
arch/x86/boot/compressed/sl_stub.S:
#define mleh_rva(X) (((X) - mle_header) + MLE_HEADER_OFFSET)
.section ".rodata.mle_header", "a"
SYM_DATA_START(mle_header)
.long 0x9082ac5a /* UUID0 */
.long 0x74a7476f /* UUID1 */
.long 0xa2555c0f /* UUID2 */
.long 0x42b651cb /* UUID3 */
.long 0x00000034 /* MLE header size */
.long 0x00020002 /* MLE version 2.2 */
.long mleh_rva(sl_stub_entry) /* Linear entry point of MLE (virt. address) */
.long 0x00000000 /* First valid page of MLE */
.long 0x00000000 /* Offset within binary of first byte of MLE */
.long 0x00000000 /* Offset within binary of last byte + 1 of MLE */
.long 0x00000223 /* Bit vector of MLE-supported capabilities */
.long 0x00000000 /* Starting linear address of command line (unused) */
.long 0x00000000 /* Ending linear address of command line (unused) */
SYM_DATA_END(mle_header)
Of course MLE_HEADER_OFFSET has to be defined as a constant somewhere.
Anyway, is it acceptable?
There is also another problem. We have to put into mle_header size of
the Linux kernel image. Currently it is done by the bootloader but
I think it is not a role of the bootloader. The kernel image should
provide all data describing its properties and do not rely on the
bootloader to do that. Ross and I investigated various options but we
did not find a good/simple way to do that. Could you suggest how we
should do that or at least where we should take a look to get some
ideas?
Daniel
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next prev parent reply other threads:[~2020-10-15 18:27 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 14:58 [PATCH 00/13] x86: Trenchboot secure dynamic launch Linux kernel support Ross Philipson
2020-09-24 14:58 ` [PATCH 01/13] x86: Secure Launch Kconfig Ross Philipson
2020-09-25 2:08 ` Randy Dunlap
2020-09-25 14:59 ` Ross Philipson
2020-09-24 14:58 ` [PATCH 02/13] x86: Secure Launch main header file Ross Philipson
2020-09-24 14:58 ` [PATCH 03/13] x86: Add early SHA support for Secure Launch early measurements Ross Philipson
2020-09-29 17:26 ` Jason Andryuk
2020-09-24 14:58 ` [PATCH 04/13] x86: Add early TPM TIS/CRB interface support for Secure Launch Ross Philipson
2020-09-24 14:58 ` [PATCH 05/13] x86: Add early TPM1.2/TPM2.0 " Ross Philipson
2020-09-25 5:43 ` Jarkko Sakkinen
2020-09-29 23:47 ` Daniel P. Smith
2020-09-30 3:19 ` Jarkko Sakkinen
2020-09-30 3:24 ` Jarkko Sakkinen
2021-01-20 0:33 ` Daniel P. Smith
2020-09-24 14:58 ` [PATCH 06/13] x86: Add early general TPM " Ross Philipson
2020-09-24 14:58 ` [PATCH 07/13] x86: Secure Launch kernel early boot stub Ross Philipson
2020-09-24 17:38 ` Arvind Sankar
2020-09-25 14:56 ` Ross Philipson
2020-09-25 19:18 ` Arvind Sankar
2020-09-29 14:03 ` Ross Philipson
2020-09-29 14:53 ` Arvind Sankar
2020-10-15 18:26 ` Daniel Kiper [this message]
2020-10-16 20:51 ` Arvind Sankar
2020-10-19 14:38 ` Ross Philipson
2020-10-19 17:06 ` Arvind Sankar
2020-10-19 19:00 ` Ross Philipson
2020-10-19 14:51 ` Daniel Kiper
2020-10-19 17:18 ` Arvind Sankar
2020-10-21 15:28 ` Daniel Kiper
2020-10-21 16:18 ` Arvind Sankar
2020-10-21 20:36 ` Ross Philipson
2020-09-24 14:58 ` [PATCH 08/13] x86: Secure Launch kernel late " Ross Philipson
2020-09-24 14:58 ` [PATCH 09/13] x86: Secure Launch SMP bringup support Ross Philipson
2020-09-24 14:58 ` [PATCH 10/13] x86: Secure Launch adding event log securityfs Ross Philipson
2020-09-24 14:58 ` [PATCH 11/13] kexec: Secure Launch kexec SEXIT support Ross Philipson
2020-09-24 14:58 ` [PATCH 12/13] reboot: Secure Launch SEXIT support on reboot paths Ross Philipson
2020-09-24 14:58 ` [PATCH 13/13] tpm: Allow locality 2 to be set when initializing the TPM for Secure Launch Ross Philipson
2020-09-25 5:30 ` [PATCH 00/13] x86: Trenchboot secure dynamic launch Linux kernel support Jarkko Sakkinen
2020-09-25 21:32 ` Daniel P. Smith
2020-09-27 23:59 ` Jarkko Sakkinen
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