|
 |
c4e390 |
From 02bdaed98f9a17a06f71ce7e21d9af2bd6547dfc Mon Sep 17 00:00:00 2001
|
|
|
c4e390 |
From: Dimitri John Ledkov <xnox@ubuntu.com>
|
|
|
c4e390 |
Date: Wed, 22 Jul 2020 11:31:43 +0100
|
|
|
c4e390 |
Subject: [PATCH 333/336] linuxefi: fail kernel validation without shim
|
|
|
c4e390 |
protocol.
|
|
|
c4e390 |
|
|
|
c4e390 |
If certificates that signed grub are installed into db, grub can be
|
|
|
c4e390 |
booted directly. It will then boot any kernel without signature
|
|
|
c4e390 |
validation. The booted kernel will think it was booted in secureboot
|
|
|
c4e390 |
mode and will implement lockdown, yet it could have been tampered.
|
|
|
c4e390 |
|
|
|
c4e390 |
This version of the patch skips calling verification, when booted
|
|
|
c4e390 |
without secureboot. And is indented with gnu ident.
|
|
|
c4e390 |
|
|
|
c4e390 |
CVE-2020-15705
|
|
|
c4e390 |
|
|
|
c4e390 |
Reported-by: Mathieu Trudel-Lapierre <cyphermox@ubuntu.com>
|
|
|
c4e390 |
Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
|
|
|
c4e390 |
---
|
|
|
c4e390 |
grub-core/loader/arm64/linux.c | 12 ++++++++----
|
|
|
c4e390 |
grub-core/loader/efi/chainloader.c | 4 +---
|
|
|
c4e390 |
grub-core/loader/efi/linux.c | 1 +
|
|
|
c4e390 |
grub-core/loader/i386/efi/linux.c | 13 ++++++++-----
|
|
|
c4e390 |
4 files changed, 18 insertions(+), 12 deletions(-)
|
|
|
c4e390 |
|
|
|
c4e390 |
diff --git a/grub-core/loader/arm64/linux.c b/grub-core/loader/arm64/linux.c
|
|
|
c4e390 |
index 1eb332a892c..d0a428d05fc 100644
|
|
|
c4e390 |
--- a/grub-core/loader/arm64/linux.c
|
|
|
c4e390 |
+++ b/grub-core/loader/arm64/linux.c
|
|
|
c4e390 |
@@ -439,11 +439,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
|
|
|
c4e390 |
|
|
|
c4e390 |
grub_dprintf ("linux", "kernel @ %p\n", kernel_addr);
|
|
|
c4e390 |
|
|
|
c4e390 |
- rc = grub_linuxefi_secure_validate (kernel_addr, kernel_size);
|
|
|
c4e390 |
- if (rc < 0)
|
|
|
c4e390 |
+ if (grub_efi_secure_boot ())
|
|
|
c4e390 |
{
|
|
|
c4e390 |
- grub_error (GRUB_ERR_INVALID_COMMAND, N_("%s has invalid signature"), argv[0]);
|
|
|
c4e390 |
- goto fail;
|
|
|
c4e390 |
+ rc = grub_linuxefi_secure_validate (kernel_addr, kernel_size);
|
|
|
c4e390 |
+ if (rc <= 0)
|
|
|
c4e390 |
+ {
|
|
|
c4e390 |
+ grub_error (GRUB_ERR_INVALID_COMMAND,
|
|
|
c4e390 |
+ N_("%s has invalid signature"), argv[0]);
|
|
|
c4e390 |
+ goto fail;
|
|
|
c4e390 |
+ }
|
|
|
c4e390 |
}
|
|
|
c4e390 |
|
|
|
c4e390 |
pe = (void *)((unsigned long)kernel_addr + lh.hdr_offset);
|
|
|
c4e390 |
diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
|
|
|
c4e390 |
index dbcdf333b62..001766bdf68 100644
|
|
|
c4e390 |
--- a/grub-core/loader/efi/chainloader.c
|
|
|
c4e390 |
+++ b/grub-core/loader/efi/chainloader.c
|
|
|
c4e390 |
@@ -1082,9 +1082,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
|
|
|
c4e390 |
|
|
|
c4e390 |
return 0;
|
|
|
c4e390 |
}
|
|
|
c4e390 |
-
|
|
|
c4e390 |
- grub_file_close (file);
|
|
|
c4e390 |
- grub_device_close (dev);
|
|
|
c4e390 |
+ // -1 fall-through to fail
|
|
|
c4e390 |
|
|
|
c4e390 |
fail:
|
|
|
c4e390 |
if (dev)
|
|
|
c4e390 |
diff --git a/grub-core/loader/efi/linux.c b/grub-core/loader/efi/linux.c
|
|
|
c4e390 |
index 7fe7201a388..d9b5380cfd3 100644
|
|
|
c4e390 |
--- a/grub-core/loader/efi/linux.c
|
|
|
c4e390 |
+++ b/grub-core/loader/efi/linux.c
|
|
|
c4e390 |
@@ -33,6 +33,7 @@ struct grub_efi_shim_lock
|
|
|
c4e390 |
};
|
|
|
c4e390 |
typedef struct grub_efi_shim_lock grub_efi_shim_lock_t;
|
|
|
c4e390 |
|
|
|
c4e390 |
+// Returns 1 on success, -1 on error, 0 when not available
|
|
|
c4e390 |
int
|
|
|
c4e390 |
grub_linuxefi_secure_validate (void *data, grub_uint32_t size)
|
|
|
c4e390 |
{
|
|
|
c4e390 |
diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c
|
|
|
c4e390 |
index 95dbb9e20af..c146bc58e3d 100644
|
|
|
c4e390 |
--- a/grub-core/loader/i386/efi/linux.c
|
|
|
c4e390 |
+++ b/grub-core/loader/i386/efi/linux.c
|
|
|
c4e390 |
@@ -201,12 +201,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
|
|
|
c4e390 |
goto fail;
|
|
|
c4e390 |
}
|
|
|
c4e390 |
|
|
|
c4e390 |
- rc = grub_linuxefi_secure_validate (kernel, filelen);
|
|
|
c4e390 |
- if (rc < 0)
|
|
|
c4e390 |
+ if (grub_efi_secure_boot ())
|
|
|
c4e390 |
{
|
|
|
c4e390 |
- grub_error (GRUB_ERR_INVALID_COMMAND, N_("%s has invalid signature"),
|
|
|
c4e390 |
- argv[0]);
|
|
|
c4e390 |
- goto fail;
|
|
|
c4e390 |
+ rc = grub_linuxefi_secure_validate (kernel, filelen);
|
|
|
c4e390 |
+ if (rc <= 0)
|
|
|
c4e390 |
+ {
|
|
|
c4e390 |
+ grub_error (GRUB_ERR_INVALID_COMMAND,
|
|
|
c4e390 |
+ N_("%s has invalid signature"), argv[0]);
|
|
|
c4e390 |
+ goto fail;
|
|
|
c4e390 |
+ }
|
|
|
c4e390 |
}
|
|
|
c4e390 |
|
|
|
c4e390 |
params = grub_efi_allocate_pages_max (0x3fffffff,
|
|
|
c4e390 |
--
|
|
|
c4e390 |
2.26.2
|
|
|
c4e390 |
|