|
 |
9723a8 |
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
|
|
c294fc |
From: Dimitri John Ledkov <xnox@ubuntu.com>
|
|
|
c294fc |
Date: Wed, 22 Jul 2020 11:31:43 +0100
|
|
|
9723a8 |
Subject: [PATCH] linuxefi: fail kernel validation without shim protocol.
|
|
|
c294fc |
|
|
|
c294fc |
If certificates that signed grub are installed into db, grub can be
|
|
|
c294fc |
booted directly. It will then boot any kernel without signature
|
|
|
c294fc |
validation. The booted kernel will think it was booted in secureboot
|
|
|
c294fc |
mode and will implement lockdown, yet it could have been tampered.
|
|
|
c294fc |
|
|
|
c294fc |
This version of the patch skips calling verification, when booted
|
|
|
c294fc |
without secureboot. And is indented with gnu ident.
|
|
|
c294fc |
|
|
|
c294fc |
CVE-2020-15705
|
|
|
c294fc |
|
|
|
c294fc |
Reported-by: Mathieu Trudel-Lapierre <cyphermox@ubuntu.com>
|
|
|
c294fc |
Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
|
|
|
c294fc |
---
|
|
|
c294fc |
grub-core/loader/arm64/linux.c | 12 ++++++++----
|
|
|
c294fc |
grub-core/loader/efi/chainloader.c | 1 +
|
|
|
c294fc |
grub-core/loader/efi/linux.c | 1 +
|
|
|
c294fc |
grub-core/loader/i386/efi/linux.c | 13 ++++++++-----
|
|
|
c294fc |
4 files changed, 18 insertions(+), 9 deletions(-)
|
|
|
c294fc |
|
|
|
c294fc |
diff --git a/grub-core/loader/arm64/linux.c b/grub-core/loader/arm64/linux.c
|
|
|
b71686 |
index e1110749e..7a076c131 100644
|
|
|
c294fc |
--- a/grub-core/loader/arm64/linux.c
|
|
|
c294fc |
+++ b/grub-core/loader/arm64/linux.c
|
|
|
c294fc |
@@ -381,11 +381,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
|
|
|
c294fc |
|
|
|
c294fc |
grub_dprintf ("linux", "kernel @ %p\n", kernel_addr);
|
|
|
c294fc |
|
|
|
c294fc |
- rc = grub_linuxefi_secure_validate (kernel_addr, kernel_size);
|
|
|
c294fc |
- if (rc < 0)
|
|
|
c294fc |
+ if (grub_efi_secure_boot ())
|
|
|
c294fc |
{
|
|
|
c294fc |
- grub_error (GRUB_ERR_INVALID_COMMAND, N_("%s has invalid signature"), argv[0]);
|
|
|
c294fc |
- goto fail;
|
|
|
c294fc |
+ rc = grub_linuxefi_secure_validate (kernel_addr, kernel_size);
|
|
|
c294fc |
+ if (rc <= 0)
|
|
|
c294fc |
+ {
|
|
|
c294fc |
+ grub_error (GRUB_ERR_INVALID_COMMAND,
|
|
|
c294fc |
+ N_("%s has invalid signature"), argv[0]);
|
|
|
c294fc |
+ goto fail;
|
|
|
c294fc |
+ }
|
|
|
c294fc |
}
|
|
|
c294fc |
|
|
|
c294fc |
pe = (void *)((unsigned long)kernel_addr + lh.hdr_offset);
|
|
|
c294fc |
diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
|
|
|
b71686 |
index 8b99cf23e..a93edc975 100644
|
|
|
c294fc |
--- a/grub-core/loader/efi/chainloader.c
|
|
|
c294fc |
+++ b/grub-core/loader/efi/chainloader.c
|
|
|
c294fc |
@@ -1079,6 +1079,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
|
|
|
c294fc |
|
|
|
c294fc |
return 0;
|
|
|
c294fc |
}
|
|
|
c294fc |
+ // -1 fall-through to fail
|
|
|
c294fc |
|
|
|
c294fc |
fail:
|
|
|
c294fc |
if (dev)
|
|
|
c294fc |
diff --git a/grub-core/loader/efi/linux.c b/grub-core/loader/efi/linux.c
|
|
|
b71686 |
index e09f82486..927d89a90 100644
|
|
|
c294fc |
--- a/grub-core/loader/efi/linux.c
|
|
|
c294fc |
+++ b/grub-core/loader/efi/linux.c
|
|
|
c294fc |
@@ -33,6 +33,7 @@ struct grub_efi_shim_lock
|
|
|
c294fc |
};
|
|
|
c294fc |
typedef struct grub_efi_shim_lock grub_efi_shim_lock_t;
|
|
|
c294fc |
|
|
|
c294fc |
+// Returns 1 on success, -1 on error, 0 when not available
|
|
|
c294fc |
int
|
|
|
c294fc |
grub_linuxefi_secure_validate (void *data, grub_uint32_t size)
|
|
|
c294fc |
{
|
|
|
c294fc |
diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c
|
|
|
b71686 |
index ade7ab8f5..361e503cb 100644
|
|
|
c294fc |
--- a/grub-core/loader/i386/efi/linux.c
|
|
|
c294fc |
+++ b/grub-core/loader/i386/efi/linux.c
|
|
|
c294fc |
@@ -206,12 +206,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
|
|
|
c294fc |
grub_tpm_measure (kernel, filelen, GRUB_BINARY_PCR, "grub_linuxefi", "Kernel");
|
|
|
c294fc |
grub_print_error();
|
|
|
c294fc |
|
|
|
c294fc |
- rc = grub_linuxefi_secure_validate (kernel, filelen);
|
|
|
c294fc |
- if (rc < 0)
|
|
|
c294fc |
+ if (grub_efi_secure_boot ())
|
|
|
c294fc |
{
|
|
|
c294fc |
- grub_error (GRUB_ERR_INVALID_COMMAND, N_("%s has invalid signature"),
|
|
|
c294fc |
- argv[0]);
|
|
|
c294fc |
- goto fail;
|
|
|
c294fc |
+ rc = grub_linuxefi_secure_validate (kernel, filelen);
|
|
|
c294fc |
+ if (rc <= 0)
|
|
|
c294fc |
+ {
|
|
|
c294fc |
+ grub_error (GRUB_ERR_INVALID_COMMAND,
|
|
|
c294fc |
+ N_("%s has invalid signature"), argv[0]);
|
|
|
c294fc |
+ goto fail;
|
|
|
c294fc |
+ }
|
|
|
c294fc |
}
|
|
|
c294fc |
|
|
|
c294fc |
params = grub_efi_allocate_pages_max (0x3fffffff,
|