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Date: Tue, 12 Mar 2019 10:34:54 -0700
From: hpa@...or.com
To: Ross Philipson <ross.philipson@...cle.com>,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
CC: x86@...nel.org, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
corbet@....net, konrad.wilk@...cle.com, kanth.ghatraju@...cle.com,
daniel.kiper@...cle.com, boris.ostrovsky@...cle.com,
dpsmith@...rtussolutions.com, ross.philipson@...cle.com
Subject: Re: [PATCH 1/1] x86: Secure Launch boot protocol
On March 11, 2019 8:04:23 AM PDT, Ross Philipson <ross.philipson@...cle.com> wrote:
>The open source project called Trenchboot aims to make Linux directly
>bootable
>into a secure late launch environment via Intel TXT or AMD SKINIT.
>Though the
>project name is Trenchboot, this new feature is referred to as Secure
>Launch.
>In this scheme, the entire Linux image becomes the Measured Launch
>Environment
>(MLE). This term comes from the Intel TXT specification and means the
>image
>whose measurement is rooted in the TXT hardware. AMD's SKINIT does
>something
>similar with the same end result. For TXT, see the "Intel Trusted
>Execution
>Technology" specification. For SKINIT, see the "AMD64 Architecture
>Programmer’s Manual Volume 2: System Programming", section 15.27.
>
>The boot protocol extension introduces a new Linux boot parameter in
>the
>setup_header to convey the offset of the MLE header within the
>compressed kernel
>image (NOTE the MLE header is in the uncompressed protected mode entry
>portion).
>This header is used to initiate the entire secure late launch process.
>The
>header offset is written using the same method that is used to setup
>the
>handover_offset of the EFI handover protocol.
>
>Signed-off-by: Ross Philipson <ross.philipson@...cle.com>
>Reviewed-by: Daniel Kiper <daniel.kiper@...cle.com>
>---
> Documentation/x86/boot.txt | 15 +++++++++++++++
> arch/x86/Kconfig | 7 +++++++
> arch/x86/boot/Makefile | 2 +-
> arch/x86/boot/header.S | 3 ++-
> arch/x86/boot/tools/build.c | 16 ++++++++++++++++
> arch/x86/include/uapi/asm/bootparam.h | 1 +
> 6 files changed, 42 insertions(+), 2 deletions(-)
>
>diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
>index f4c2a97bfdbd..958acd71815f 100644
>--- a/Documentation/x86/boot.txt
>+++ b/Documentation/x86/boot.txt
>@@ -61,6 +61,9 @@ Protocol 2.12: (Kernel 3.8) Added the xloadflags
>field and extension fields
> to struct boot_params for loading bzImage and ramdisk
> above 4G in 64bit.
>
>+Protocol 2.14: (Kernel 5.1) Added a field for offset of measured
>launch
>+ environment (MLE) header.
>+
> **** MEMORY LAYOUT
>
> The traditional memory map for the kernel loader, used for Image or
>@@ -197,6 +200,7 @@ Offset Proto Name Meaning
> 0258/8 2.10+ pref_address Preferred loading address
> 0260/4 2.10+ init_size Linear memory required during initialization
> 0264/4 2.11+ handover_offset Offset of handover entry point
>+0268/4 2.14+ mle_header_offset Offset of measured launch environement
>header
>
>(1) For backwards compatibility, if the setup_sects field contains 0,
>the
> real value is 4.
>@@ -744,6 +748,17 @@ Offset/size: 0x264/4
>
> See EFI HANDOVER PROTOCOL below for more details.
>
>+Field name: mle_header_offset
>+Type: read
>+Offset/size: 0x268/4
>+
>+ This field is the offset from the beginning of the kernel image to
>+ the measured launch environment header structure. Boot loaders
>launching
>+ a kernel using Intel TXT or AMD SKINT secure late launch features
>use
>+ this header to set up the launch environment. It is called
>mle_header
>+ and is embedded in the Linux image in the uncompressed protected
>mode
>+ entry region.
>+
>
> **** THE IMAGE CHECKSUM
>
>diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>index 68261430fe6e..508f1cc6795f 100644
>--- a/arch/x86/Kconfig
>+++ b/arch/x86/Kconfig
>@@ -1965,6 +1965,13 @@ config EFI_MIXED
>
> If unsure, say N.
>
>+config SECURE_LAUNCH_STUB
>+ bool "Secure Launch stub support"
>+ depends on X86_64
>+ ---help---
>+ This kernel feature allows a bzImage to be loaded directly
>+ through Intel TXT or AMD SKINIT measured launch.
>+
> config SECCOMP
> def_bool y
> prompt "Enable seccomp to safely compute untrusted bytecode"
>diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
>index 9b5adae9cc40..03c989bb36ab 100644
>--- a/arch/x86/boot/Makefile
>+++ b/arch/x86/boot/Makefile
>@@ -87,7 +87,7 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
>
> SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
>
>-sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW]
>\(startup_32\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|input_data\|_end\|_ehead\|_text\|z_.*\)$$/\#define
>ZO_\2 0x\1/p'
>+sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW]
>\(startup_32\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|mle_header\|input_data\|_end\|_ehead\|_text\|z_.*\)$$/\#define
>ZO_\2 0x\1/p'
>
> quiet_cmd_zoffset = ZOFFSET $@
> cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@
>diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
>index 850b8762e889..9f8f8c1db11a 100644
>--- a/arch/x86/boot/header.S
>+++ b/arch/x86/boot/header.S
>@@ -300,7 +300,7 @@ _start:
> # Part 2 of the header, from the old setup.S
>
> .ascii "HdrS" # header signature
>- .word 0x020d # header version number (>= 0x0105)
>+ .word 0x020e # header version number (>= 0x0105)
> # or else old loadlin-1.5 will fail)
> .globl realmode_swtch
> realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
>@@ -557,6 +557,7 @@ pref_address: .quad LOAD_PHYSICAL_ADDR # preferred
>load addr
>
> init_size: .long INIT_SIZE # kernel initialization size
> handover_offset: .long 0 # Filled in by build.c
>+mle_header_offset: .long 0 # Filled in by build.c
>
># End of setup header
>#####################################################
>
>diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
>index a93d44e58f9c..0dd6f1ffc66d 100644
>--- a/arch/x86/boot/tools/build.c
>+++ b/arch/x86/boot/tools/build.c
>@@ -56,6 +56,7 @@ u8 buf[SETUP_SECT_MAX*512];
> unsigned long efi32_stub_entry;
> unsigned long efi64_stub_entry;
> unsigned long efi_pe_entry;
>+unsigned long mle_header;
> unsigned long startup_64;
>
>/*----------------------------------------------------------------------*/
>@@ -289,6 +290,18 @@ static inline int reserve_pecoff_reloc_section(int
>c)
> }
> #endif /* CONFIG_EFI_STUB */
>
>+#ifdef CONFIG_SECURE_LAUNCH_STUB
>+
>+static void slaunch_stub_entry_update(void)
>+{
>+ put_unaligned_le32(mle_header, &buf[0x268]);
>+}
>+
>+#else
>+
>+static void slaunch_stub_entry_update(void) {}
>+
>+#endif /* CONFIG_SECURE_LAUNCH_STUB */
>
> /*
>* Parse zoffset.h and find the entry points. We could just #include
>zoffset.h
>@@ -321,6 +334,7 @@ static void parse_zoffset(char *fname)
> PARSE_ZOFS(p, efi32_stub_entry);
> PARSE_ZOFS(p, efi64_stub_entry);
> PARSE_ZOFS(p, efi_pe_entry);
>+ PARSE_ZOFS(p, mle_header);
> PARSE_ZOFS(p, startup_64);
>
> p = strchr(p, '\n');
>@@ -410,6 +424,8 @@ int main(int argc, char ** argv)
>
> efi_stub_entry_update();
>
>+ slaunch_stub_entry_update();
>+
> crc = partial_crc32(buf, i, crc);
> if (fwrite(buf, 1, i, dest) != i)
> die("Writing setup failed");
>diff --git a/arch/x86/include/uapi/asm/bootparam.h
>b/arch/x86/include/uapi/asm/bootparam.h
>index 60733f137e9a..92cd63c99c9e 100644
>--- a/arch/x86/include/uapi/asm/bootparam.h
>+++ b/arch/x86/include/uapi/asm/bootparam.h
>@@ -86,6 +86,7 @@ struct setup_header {
> __u64 pref_address;
> __u32 init_size;
> __u32 handover_offset;
>+ __u32 mle_header_offset;
> } __attribute__((packed));
>
> struct sys_desc_table {
Double NAK – I'm in a meeting right now but with clarify shortly.
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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