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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH] EFI: Enable booting unified hypervisor/kernel/initrd images
This patch adds support for bundling the xen.efi hypervisor, the xen.cfg
configuration file, the Linux kernel and initrd, as well as the XSM, and
CPU microcode into a single "unified" EFI executable. The resulting EFI
executable can be invoked directly from the UEFI Boot Manager, removing
the need to use a separate loader like grub as well as removing
dependencies on local filesystem access.
It is inspired by systemd-boot's unified kernel technique and borrows the
function to locate PE sections from systemd's LGPL'ed code. During EFI
boot, Xen looks at its own loaded image to locate the PE sections for
the configuration, kernel, etc, which are included after building xen.efi
using objcopy to add named sections for each input file. This allows an
administrator to update the components independently without requiring
rebuilding xen.
The unified image can also be signed by sbsigntool for verification
by UEFI Secure Boot. If secure boot is enabled, the Xen command line
arguments are ignored. Unlike the shim based verification, the signature
covers the entire Xen+config+kernel+initrd unified file. This also ensures
that properly configured platforms will measure the entire runtime into
the TPM for unsealing secrets or remote attestation.
Signed-off-by: Trammell Hudson <hudson@xxxxxxxx>
diff --git a/xen/Makefile b/xen/Makefile
index a87bb225dc..e4e4c6d5c1 100644
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -355,7 +355,7 @@ $(TARGET): delete-unfresh-files
$(MAKE) -C tools
$(MAKE) -f $(BASEDIR)/Rules.mk include/xen/compile.h
[ -e include/asm ] || ln -sf asm-$(TARGET_ARCH) include/asm
- [ -e arch/$(TARGET_ARCH)/efi ] && for f in boot.c runtime.c compat.c
efi.h;\
+ [ -e arch/$(TARGET_ARCH)/efi ] && for f in boot.c pe.c runtime.c
compat.c efi.h;\
do test -r arch/$(TARGET_ARCH)/efi/$$f || \
ln -nsf ../../../common/efi/$$f arch/$(TARGET_ARCH)/efi/; \
done; \
diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
index 6527cb0bdf..483dec465d 100644
--- a/xen/arch/arm/efi/efi-boot.h
+++ b/xen/arch/arm/efi/efi-boot.h
@@ -395,7 +395,7 @@ static void __init efi_arch_cfg_file_early(EFI_FILE_HANDLE
dir_handle, char *sec
blexit(L"Unable to create new FDT");
}
-static void __init efi_arch_cfg_file_late(EFI_FILE_HANDLE dir_handle, char
*section)
+static void __init efi_arch_cfg_file_late(EFI_LOADED_IMAGE * image,
EFI_FILE_HANDLE dir_handle, char *section)
{
}
diff --git a/xen/arch/x86/efi/Makefile b/xen/arch/x86/efi/Makefile
index 4b2b010a80..ae666aa14c 100644
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -8,7 +8,7 @@ cmd_objcopy_o_ihex = $(OBJCOPY) -I ihex -O binary $< $@
boot.init.o: buildid.o
-EFIOBJ := boot.init.o compat.o runtime.o
+EFIOBJ := boot.init.o pe.init.o compat.o runtime.o
$(call cc-option-add,cflags-stack-boundary,CC,-mpreferred-stack-boundary=4)
$(EFIOBJ): CFLAGS-stack-boundary := $(cflags-stack-boundary)
diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index 7188c9a551..e2650c0440 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -276,9 +276,11 @@ static void __init efi_arch_cfg_file_early(EFI_FILE_HANDLE
dir_handle, char *sec
{
}
-static void __init efi_arch_cfg_file_late(EFI_FILE_HANDLE dir_handle, char
*section)
+static void __init efi_arch_cfg_file_late(EFI_LOADED_IMAGE * image,
EFI_FILE_HANDLE dir_handle, char *section)
{
union string name;
+ if ( read_section(image, ".ucode", &ucode, NULL) )
+ return;
name.s = get_value(&cfg, section, "ucode");
if ( !name.s )
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 0273f79152..ba691b1890 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -156,6 +156,7 @@ SECTIONS
__note_gnu_build_id_end = .;
} :note :text
#elif defined(BUILD_ID_EFI)
+ . = ALIGN(32); /* workaround binutils section overlap bug */
DECL_SECTION(.buildid) {
__note_gnu_build_id_start = .;
*(.buildid)
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index 5a520bf21d..258433331f 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -102,6 +102,7 @@ union string {
struct file {
UINTN size;
+ bool need_to_free;
union {
EFI_PHYSICAL_ADDRESS addr;
void *ptr;
@@ -121,6 +122,8 @@ static CHAR16 *s2w(union string *str);
static char *w2s(const union string *str);
static bool read_file(EFI_FILE_HANDLE dir_handle, CHAR16 *name,
struct file *file, char *options);
+static bool read_section(EFI_LOADED_IMAGE * image,
+ char * name, struct file *file, char *options);
static size_t wstrlen(const CHAR16 * s);
static int set_color(u32 mask, int bpp, u8 *pos, u8 *sz);
static bool match_guid(const EFI_GUID *guid1, const EFI_GUID *guid2);
@@ -330,13 +333,13 @@ static void __init noreturn blexit(const CHAR16 *str)
if ( !efi_bs )
efi_arch_halt();
- if ( cfg.addr )
+ if ( cfg.addr && cfg.need_to_free)
efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
- if ( kernel.addr )
+ if ( kernel.addr && kernel.need_to_free)
efi_bs->FreePages(kernel.addr, PFN_UP(kernel.size));
- if ( ramdisk.addr )
+ if ( ramdisk.addr && ramdisk.need_to_free)
efi_bs->FreePages(ramdisk.addr, PFN_UP(ramdisk.size));
- if ( xsm.addr )
+ if ( xsm.addr && xsm.need_to_free)
efi_bs->FreePages(xsm.addr, PFN_UP(xsm.size));
efi_arch_blexit();
@@ -589,6 +592,21 @@ static char * __init split_string(char *s)
return NULL;
}
+static void __init display_file_info(CHAR16 * name, struct file * file, char *
options)
+{
+ if ( file == &cfg )
+ return;
+
+ PrintStr(name);
+ PrintStr(L": ");
+ DisplayUint(file->addr, 2 * sizeof(file->addr));
+ PrintStr(L"-");
+ DisplayUint(file->addr + file->size, 2 * sizeof(file->addr));
+ PrintStr(newline);
+
+ efi_arch_handle_module(file, name, options);
+}
+
static bool __init read_file(EFI_FILE_HANDLE dir_handle, CHAR16 *name,
struct file *file, char *options)
{
@@ -619,6 +637,7 @@ static bool __init read_file(EFI_FILE_HANDLE dir_handle,
CHAR16 *name,
what = what ?: L"Seek";
else
{
+ file->need_to_free = true;
file->addr = min(1UL << (32 + PAGE_SHIFT),
HYPERVISOR_VIRT_END - DIRECTMAP_VIRT_START);
ret = efi_bs->AllocatePages(AllocateMaxAddress, EfiLoaderData,
@@ -632,16 +651,7 @@ static bool __init read_file(EFI_FILE_HANDLE dir_handle,
CHAR16 *name,
else
{
file->size = size;
- if ( file != &cfg )
- {
- PrintStr(name);
- PrintStr(L": ");
- DisplayUint(file->addr, 2 * sizeof(file->addr));
- PrintStr(L"-");
- DisplayUint(file->addr + size, 2 * sizeof(file->addr));
- PrintStr(newline);
- efi_arch_handle_module(file, name, options);
- }
+ display_file_info(name, file, options);
ret = FileHandle->Read(FileHandle, &file->size, file->ptr);
if ( !EFI_ERROR(ret) && file->size != size )
@@ -665,6 +675,25 @@ static bool __init read_file(EFI_FILE_HANDLE dir_handle,
CHAR16 *name,
return true;
}
+static bool __init read_section(EFI_LOADED_IMAGE * image,
+ char * const name, struct file *file, char
*options)
+{
+ /* skip the leading "." in the section name */
+ union string name_string = { .s = name + 1 };
+
+ file->ptr = (void*) pe_find_section(image->ImageBase, image->ImageSize,
name, &file->size);
+ if ( !file->ptr )
+ return false;
+
+ file->need_to_free = false;
+
+ s2w(&name_string);
+ display_file_info(name_string.w, file, options);
+ efi_bs->FreePool(name_string.w);
+
+ return true;
+}
+
static void __init pre_parse(const struct file *cfg)
{
char *ptr = cfg->ptr, *end = ptr + cfg->size;
@@ -968,6 +997,26 @@ static void __init setup_efi_pci(void)
efi_bs->FreePool(handles);
}
+/*
+ * Logic should remain sync'ed with linux/arch/x86/xen/efi.c
+ * Secure Boot is enabled iff 'SecureBoot' is set and the system is
+ * not in Setup Mode.
+ */
+static bool __init efi_secure_boot(void)
+{
+ static const __initconst EFI_GUID global_guid = EFI_GLOBAL_VARIABLE;
+ uint8_t secboot, setupmode;
+ UINTN secboot_size = sizeof(secboot);
+ UINTN setupmode_size = sizeof(setupmode);
+
+ if ( efi_rs->GetVariable(L"SecureBoot", (EFI_GUID *)&global_guid, NULL,
&secboot_size, &secboot) != EFI_SUCCESS )
+ return false;
+ if ( efi_rs->GetVariable(L"SetupMode", (EFI_GUID *)&global_guid, NULL,
&setupmode_size, &setupmode) != EFI_SUCCESS )
+ return false;
+
+ return secboot == 1 && setupmode == 0;
+}
+
static void __init efi_variables(void)
{
EFI_STATUS status;
@@ -1144,8 +1193,8 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
static EFI_GUID __initdata shim_lock_guid = SHIM_LOCK_PROTOCOL_GUID;
EFI_LOADED_IMAGE *loaded_image;
EFI_STATUS status;
- unsigned int i, argc;
- CHAR16 **argv, *file_name, *cfg_file_name = NULL, *options = NULL;
+ unsigned int i, argc = 0;
+ CHAR16 **argv = NULL, *file_name, *cfg_file_name = NULL, *options = NULL;
UINTN gop_mode = ~0;
EFI_SHIM_LOCK_PROTOCOL *shim_lock;
EFI_GRAPHICS_OUTPUT_PROTOCOL *gop = NULL;
@@ -1153,6 +1202,7 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
bool base_video = false;
char *option_str;
bool use_cfg_file;
+ bool secure = false;
__set_bit(EFI_BOOT, &efi_flags);
__set_bit(EFI_LOADER, &efi_flags);
@@ -1171,8 +1221,10 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
PrintErrMesg(L"No Loaded Image Protocol", status);
efi_arch_load_addr_check(loaded_image);
+ secure = efi_secure_boot();
- if ( use_cfg_file )
+ /* If UEFI Secure Boot is enabled, do not parse the command line */
+ if ( use_cfg_file && !secure )
{
UINTN offset = 0;
@@ -1230,6 +1282,8 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
PrintStr(L"Xen " __stringify(XEN_VERSION) "." __stringify(XEN_SUBVERSION)
XEN_EXTRAVERSION " (c/s " XEN_CHANGESET ") EFI loader\r\n");
+ if ( secure )
+ PrintStr(L"UEFI Secure Boot enabled\r\n");
efi_arch_relocate_image(0);
@@ -1249,9 +1303,13 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
/* Get the file system interface. */
dir_handle = get_parent_handle(loaded_image, &file_name);
- /* Read and parse the config file. */
- if ( !cfg_file_name )
+ if ( read_section(loaded_image, ".config", &cfg, NULL) )
{
+ PrintStr(L"Using unified config file\r\n");
+ }
+ else if ( !cfg_file_name )
+ {
+ /* Read and parse the config file. */
CHAR16 *tail;
while ( (tail = point_tail(file_name)) != NULL )
@@ -1303,26 +1361,36 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
efi_arch_cfg_file_early(dir_handle, section.s);
option_str = split_string(name.s);
- read_file(dir_handle, s2w(&name), &kernel, option_str);
- efi_bs->FreePool(name.w);
-
- if ( !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
- (void **)&shim_lock)) &&
- (status = shim_lock->Verify(kernel.ptr, kernel.size)) !=
EFI_SUCCESS )
- PrintErrMesg(L"Dom0 kernel image could not be verified", status);
- name.s = get_value(&cfg, section.s, "ramdisk");
- if ( name.s )
+ if ( !read_section(loaded_image, ".kernel", &kernel, option_str) )
{
- read_file(dir_handle, s2w(&name), &ramdisk, NULL);
+ read_file(dir_handle, s2w(&name), &kernel, option_str);
efi_bs->FreePool(name.w);
+
+ if ( !EFI_ERROR(efi_bs->LocateProtocol(&shim_lock_guid, NULL,
+ (void **)&shim_lock)) &&
+ (status = shim_lock->Verify(kernel.ptr, kernel.size)) !=
EFI_SUCCESS )
+ PrintErrMesg(L"Dom0 kernel image could not be verified",
status);
}
- name.s = get_value(&cfg, section.s, "xsm");
- if ( name.s )
+ if ( !read_section(loaded_image, ".ramdisk", &ramdisk, NULL) )
{
- read_file(dir_handle, s2w(&name), &xsm, NULL);
- efi_bs->FreePool(name.w);
+ name.s = get_value(&cfg, section.s, "ramdisk");
+ if ( name.s )
+ {
+ read_file(dir_handle, s2w(&name), &ramdisk, NULL);
+ efi_bs->FreePool(name.w);
+ }
+ }
+
+ if ( !read_section(loaded_image, ".xsm", &xsm, NULL) )
+ {
+ name.s = get_value(&cfg, section.s, "xsm");
+ if ( name.s )
+ {
+ read_file(dir_handle, s2w(&name), &xsm, NULL);
+ efi_bs->FreePool(name.w);
+ }
}
/*
@@ -1358,7 +1426,7 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
}
}
- efi_arch_cfg_file_late(dir_handle, section.s);
+ efi_arch_cfg_file_late(loaded_image, dir_handle, section.s);
efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
cfg.addr = 0;
diff --git a/xen/common/efi/efi.h b/xen/common/efi/efi.h
index 2e38d05f3d..d3018f81a1 100644
--- a/xen/common/efi/efi.h
+++ b/xen/common/efi/efi.h
@@ -41,3 +41,6 @@ extern UINT64 efi_apple_properties_addr;
extern UINTN efi_apple_properties_len;
const CHAR16 *wmemchr(const CHAR16 *s, CHAR16 c, UINTN n);
+
+const void * pe_find_section(const UINT8 * image_base, const size_t image_size,
+ const char * section_name, UINTN * size_out);
diff --git a/xen/common/efi/pe.c b/xen/common/efi/pe.c
new file mode 100644
index 0000000000..3440d82598
--- /dev/null
+++ b/xen/common/efi/pe.c
@@ -0,0 +1,181 @@
+/*
+ * xen/common/efi/pe.c
+ *
+ * PE executable header parser.
+ *
+ * Derived from
https://github.com/systemd/systemd/blob/master/src/boot/efi/pe.c
+ *
+ * Copyright (C) 2015 Kay Sievers <kay@xxxxxxxx>
+ * Copyright (C) 2020 Trammell Hudson <hudson@xxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ */
+
+/*
+ * The "Unified" kernel image can be generated by adding additional
+ * sections to the Xen EFI executable with objcopy, similar to how
+ * systemd-boot uses the stub to add them to the Linux kernel:
+ *
+ *
https://wiki.archlinux.org/index.php/systemd-boot#Preparing_a_unified_kernel_image
+ *
+ * The sections for the xen configuration file, the dom0 kernel, dom0 initrd,
+ * XSM and CPU microcode should be added after the Xen `.pad` section, the
+ * ending address of which can be located with:
+ *
+ * objdump -h xen.efi \
+ * | perl -ane '/\.pad/ && printf "0x%016x\n", hex($F[2]) + hex($F[3])'
+ *
+ * All the additional sections are optional and the order does not
+ * matter. The addresses do not need to be contiguous, although
+ * they should not be overlapping.
+ *
+ * objcopy \
+ * --add-section .config=xen.cfg \
+ * --change-section-vma .config=0xffff82d041000000
+ * --add-section .ucode=ucode.bin \
+ * --change-section-vma .ucode=0xffff82d041010000 \
+ * --add-section .xsm=xsm.cfg \
+ * --change-section-vma .xsm=0xffff82d041080000 \
+ * --add-section .kernel=vmlinux \
+ * --change-section-vma .kernel=0xffff82d041100000 \
+ * --add-section .ramdisk=initrd.img \
+ * --change-section-vma .initrd=0xffff82d042000000 \
+ * xen.efi \
+ * xen.unified.efi
+ *
+ * The unified executable can be signed with sbsigntool to make
+ * it usable with UEFI secure boot:
+ *
+ * sbsign \
+ * --key signing.key \
+ * --cert cert.pem \
+ * --output xen.signed.efi \
+ * xen.unified.efi
+ */
+
+#include "efi.h"
+
+struct DosFileHeader {
+ UINT8 Magic[2];
+ UINT16 LastSize;
+ UINT16 nBlocks;
+ UINT16 nReloc;
+ UINT16 HdrSize;
+ UINT16 MinAlloc;
+ UINT16 MaxAlloc;
+ UINT16 ss;
+ UINT16 sp;
+ UINT16 Checksum;
+ UINT16 ip;
+ UINT16 cs;
+ UINT16 RelocPos;
+ UINT16 nOverlay;
+ UINT16 reserved[4];
+ UINT16 OEMId;
+ UINT16 OEMInfo;
+ UINT16 reserved2[10];
+ UINT32 ExeHeader;
+} __attribute__((packed));
+
+#define PE_HEADER_MACHINE_ARM64 0xaa64
+#define PE_HEADER_MACHINE_X64 0x8664
+#define PE_HEADER_MACHINE_I386 0x014c
+
+struct PeFileHeader {
+ UINT16 Machine;
+ UINT16 NumberOfSections;
+ UINT32 TimeDateStamp;
+ UINT32 PointerToSymbolTable;
+ UINT32 NumberOfSymbols;
+ UINT16 SizeOfOptionalHeader;
+ UINT16 Characteristics;
+} __attribute__((packed));
+
+struct PeHeader {
+ UINT8 Magic[4];
+ struct PeFileHeader FileHeader;
+} __attribute__((packed));
+
+struct PeSectionHeader {
+ UINT8 Name[8];
+ UINT32 VirtualSize;
+ UINT32 VirtualAddress;
+ UINT32 SizeOfRawData;
+ UINT32 PointerToRawData;
+ UINT32 PointerToRelocations;
+ UINT32 PointerToLinenumbers;
+ UINT16 NumberOfRelocations;
+ UINT16 NumberOfLinenumbers;
+ UINT32 Characteristics;
+} __attribute__((packed));
+
+const void * __init pe_find_section(const CHAR8 * image, const UINTN
image_size,
+ const char * section_name, UINTN * size_out)
+{
+ const struct DosFileHeader * dos = (const void*) image;
+ const struct PeHeader * pe;
+ const struct PeSectionHeader * sect;
+ const UINTN name_len = strlen(section_name);
+ UINTN offset = 0;
+
+ if ( name_len > sizeof(sect->Name) )
+ return NULL;
+
+ if ( image_size < sizeof(*dos) )
+ return NULL;
+ if ( memcmp(dos->Magic, "MZ", 2) != 0 )
+ return NULL;
+
+ offset = dos->ExeHeader;
+ pe = (const void *) &image[offset];
+
+ offset += sizeof(*pe);
+ if ( image_size < offset)
+ return NULL;
+
+ if ( memcmp(pe->Magic, "PE\0\0", 4) != 0 )
+ return NULL;
+
+ /* PE32+ Subsystem type */
+#if defined(__ARM__)
+ if (pe->FileHeader.Machine != PE_HEADER_MACHINE_ARM64)
+ return NULL;
+#elif defined(__x86_64__)
+ if (pe->FileHeader.Machine != PE_HEADER_MACHINE_X64)
+ return NULL;
+#else
+ /* unknown architecture */
+ return NULL;
+#endif
+
+ offset += pe->FileHeader.SizeOfOptionalHeader;
+
+ for (UINTN i = 0 ; i < pe->FileHeader.NumberOfSections ; i++)
+ {
+ sect = (const void *) &image[offset];
+ if ( image_size < offset + sizeof(*sect) )
+ return NULL;
+
+ if ( memcmp(sect->Name, section_name, name_len) != 0
+ || image_size < sect->VirtualSize + sect->VirtualAddress )
+ {
+ offset += sizeof(*sect);
+ continue;
+ }
+
+ if ( size_out )
+ *size_out = sect->VirtualSize;
+
+ return &image[sect->VirtualAddress];
+ }
+
+ return NULL;
+}
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