[Xen-devel] [PATCH RFC 6/7] xen/x86/efi: Verify dom0 kernel with SHIM_LOCK protocol in efi_multiboot2()

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
---
 xen/arch/x86/boot/head.S    |   20 ++++++++++++++++++--
 xen/arch/x86/efi/efi-boot.h |   12 +++++++++++-
 xen/arch/x86/efi/stub.c     |    5 ++++-
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 90db661..65b3358 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -383,9 +383,13 @@ __efi64_mb2_start:
         jmp     x86_32_switch
 
 .Lefi_multiboot2_proto:
-        /* Zero EFI SystemTable and EFI ImageHandle addresses. */
+        /*
+         * Zero EFI SystemTable, EFI ImageHandle and
+         * dom0 kernel module struct addresses.
+         */
         xor     %esi,%esi
         xor     %edi,%edi
+        xor     %r14d,%r14d
 
         /* Skip Multiboot2 information fixed part. */
         lea     (MB2_fixed_sizeof+MULTIBOOT2_TAG_ALIGN-1)(%rbx),%ecx
@@ -423,6 +427,15 @@ __efi64_mb2_start:
         cmove   MB2_efi64_ih(%rcx),%rdi
         je      .Lefi_mb2_next_tag
 
+        /* Get dom0 kernel module struct address from Multiboot2 information. 
*/
+        cmpl    $MULTIBOOT2_TAG_TYPE_MODULE,MB2_tag_type(%rcx)
+        jne     .Lefi_mb2_end
+
+        test    %r14d,%r14d
+        cmovz   %ecx,%r14d
+        jmp     .Lefi_mb2_next_tag
+
+.Lefi_mb2_end:
         /* Is it the end of Multiboot2 information? */
         cmpl    $MULTIBOOT2_TAG_TYPE_END,MB2_tag_type(%rcx)
         je      .Lrun_bs
@@ -484,9 +497,12 @@ __efi64_mb2_start:
         /* Keep the stack aligned. Do not pop a single item off it. */
         mov     (%rsp),%rdi
 
+        mov     %r14d,%edx
+
         /*
          * efi_multiboot2() is called according to System V AMD64 ABI:
-         *   - IN:  %rdi - EFI ImageHandle, %rsi - EFI SystemTable.
+         *   - IN: %rdi - EFI ImageHandle, %rsi - EFI SystemTable,
+         *         %rdx - dom0 kernel module struct address.
          */
         call    efi_multiboot2
 
diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index bedac5c..6813196 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -3,6 +3,8 @@
  * is intended to be included by common/efi/boot.c _only_, and
  * therefore can define arch specific global variables.
  */
+#include <xen/types.h>
+#include <xen/multiboot2.h>
 #include <xen/vga.h>
 #include <asm/e820.h>
 #include <asm/edd.h>
@@ -47,6 +49,7 @@ extern const struct pe_base_relocs {
 
 static void __init efi_arch_relocate_image(unsigned long delta)
 {
+#if 0
     const struct pe_base_relocs *base_relocs;
 
     for ( base_relocs = __base_relocs_start; base_relocs < __base_relocs_end; )
@@ -95,6 +98,7 @@ static void __init efi_arch_relocate_image(unsigned long 
delta)
         }
         base_relocs = (const void *)(base_relocs->entries + i + (i & 1));
     }
+#endif
 }
 
 extern const s32 __trampoline_rel_start[], __trampoline_rel_stop[];
@@ -669,7 +673,9 @@ static bool __init 
efi_arch_use_config_file(EFI_SYSTEM_TABLE *SystemTable)
 
 static void efi_arch_flush_dcache_area(const void *vaddr, UINTN size) { }
 
-void __init efi_multiboot2(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE 
*SystemTable)
+void __init efi_multiboot2(EFI_HANDLE ImageHandle,
+                           EFI_SYSTEM_TABLE *SystemTable,
+                           multiboot2_tag_module_t *dom0_kernel)
 {
     EFI_GRAPHICS_OUTPUT_PROTOCOL *gop;
     UINTN cols, gop_mode = ~0, rows;
@@ -687,6 +693,10 @@ void __init efi_multiboot2(EFI_HANDLE ImageHandle, 
EFI_SYSTEM_TABLE *SystemTable
 
     gop = efi_get_gop();
 
+    if ( dom0_kernel && dom0_kernel->mod_end > dom0_kernel->mod_start )
+        efi_shim_lock((VOID *)(unsigned long)dom0_kernel->mod_start,
+                      dom0_kernel->mod_end - dom0_kernel->mod_start);
+
     if ( gop )
         gop_mode = efi_find_gop_mode(gop, 0, 0, 0);
 
diff --git a/xen/arch/x86/efi/stub.c b/xen/arch/x86/efi/stub.c
index 0c481e3..d0cba1d 100644
--- a/xen/arch/x86/efi/stub.c
+++ b/xen/arch/x86/efi/stub.c
@@ -1,7 +1,9 @@
+#include <xen/types.h>
 #include <xen/efi.h>
 #include <xen/errno.h>
 #include <xen/init.h>
 #include <xen/lib.h>
+#include <xen/multiboot2.h>
 #include <asm/page.h>
 #include <asm/efibind.h>
 #include <efi/efidef.h>
@@ -18,7 +20,8 @@
  */
 
 void __init noreturn efi_multiboot2(EFI_HANDLE ImageHandle,
-                                    EFI_SYSTEM_TABLE *SystemTable)
+                                    EFI_SYSTEM_TABLE *SystemTable,
+                                    multiboot2_tag_module_t *dom0_kernel)
 {
     static const CHAR16 __initconst err[] =
         L"Xen does not have EFI code build in!\r\nSystem halted!\r\n";
-- 
1.7.10.4


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