You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
105 lines
3.4 KiB
105 lines
3.4 KiB
4 years ago
|
From 02bdaed98f9a17a06f71ce7e21d9af2bd6547dfc Mon Sep 17 00:00:00 2001
|
||
|
|
From: Dimitri John Ledkov <xnox@ubuntu.com>
|
||
|
|
Date: Wed, 22 Jul 2020 11:31:43 +0100
|
||
|
|
Subject: [PATCH 333/336] linuxefi: fail kernel validation without shim
|
||
|
|
protocol.
|
||
|
|
|
||
|
|
If certificates that signed grub are installed into db, grub can be
|
||
|
|
booted directly. It will then boot any kernel without signature
|
||
|
|
validation. The booted kernel will think it was booted in secureboot
|
||
|
|
mode and will implement lockdown, yet it could have been tampered.
|
||
|
|
|
||
|
|
This version of the patch skips calling verification, when booted
|
||
|
|
without secureboot. And is indented with gnu ident.
|
||
|
|
|
||
|
|
CVE-2020-15705
|
||
|
|
|
||
|
|
Reported-by: Mathieu Trudel-Lapierre <cyphermox@ubuntu.com>
|
||
|
|
Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
|
||
|
|
---
|
||
|
|
grub-core/loader/arm64/linux.c | 12 ++++++++----
|
||
|
|
grub-core/loader/efi/chainloader.c | 4 +---
|
||
|
|
grub-core/loader/efi/linux.c | 1 +
|
||
|
|
grub-core/loader/i386/efi/linux.c | 13 ++++++++-----
|
||
|
|
4 files changed, 18 insertions(+), 12 deletions(-)
|
||
|
|
|
||
|
|
diff --git a/grub-core/loader/arm64/linux.c b/grub-core/loader/arm64/linux.c
|
||
|
|
index 1eb332a892c..d0a428d05fc 100644
|
||
|
|
--- a/grub-core/loader/arm64/linux.c
|
||
|
|
+++ b/grub-core/loader/arm64/linux.c
|
||
|
|
@@ -439,11 +439,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
|
||
|
|
|
||
|
|
grub_dprintf ("linux", "kernel @ %p\n", kernel_addr);
|
||
|
|
|
||
|
|
- rc = grub_linuxefi_secure_validate (kernel_addr, kernel_size);
|
||
|
|
- if (rc < 0)
|
||
|
|
+ if (grub_efi_secure_boot ())
|
||
|
|
{
|
||
|
|
- grub_error (GRUB_ERR_INVALID_COMMAND, N_("%s has invalid signature"), argv[0]);
|
||
|
|
- goto fail;
|
||
|
|
+ rc = grub_linuxefi_secure_validate (kernel_addr, kernel_size);
|
||
|
|
+ if (rc <= 0)
|
||
|
|
+ {
|
||
|
|
+ grub_error (GRUB_ERR_INVALID_COMMAND,
|
||
|
|
+ N_("%s has invalid signature"), argv[0]);
|
||
|
|
+ goto fail;
|
||
|
|
+ }
|
||
|
|
}
|
||
|
|
|
||
|
|
pe = (void *)((unsigned long)kernel_addr + lh.hdr_offset);
|
||
|
|
diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
|
||
|
|
index dbcdf333b62..001766bdf68 100644
|
||
|
|
--- a/grub-core/loader/efi/chainloader.c
|
||
|
|
+++ b/grub-core/loader/efi/chainloader.c
|
||
|
|
@@ -1082,9 +1082,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
-
|
||
|
|
- grub_file_close (file);
|
||
|
|
- grub_device_close (dev);
|
||
|
|
+ // -1 fall-through to fail
|
||
|
|
|
||
|
|
fail:
|
||
|
|
if (dev)
|
||
|
|
diff --git a/grub-core/loader/efi/linux.c b/grub-core/loader/efi/linux.c
|
||
|
|
index 7fe7201a388..d9b5380cfd3 100644
|
||
|
|
--- a/grub-core/loader/efi/linux.c
|
||
|
|
+++ b/grub-core/loader/efi/linux.c
|
||
|
|
@@ -33,6 +33,7 @@ struct grub_efi_shim_lock
|
||
|
|
};
|
||
|
|
typedef struct grub_efi_shim_lock grub_efi_shim_lock_t;
|
||
|
|
|
||
|
|
+// Returns 1 on success, -1 on error, 0 when not available
|
||
|
|
int
|
||
|
|
grub_linuxefi_secure_validate (void *data, grub_uint32_t size)
|
||
|
|
{
|
||
|
|
diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c
|
||
|
|
index 95dbb9e20af..c146bc58e3d 100644
|
||
|
|
--- a/grub-core/loader/i386/efi/linux.c
|
||
|
|
+++ b/grub-core/loader/i386/efi/linux.c
|
||
|
|
@@ -201,12 +201,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
|
||
|
|
goto fail;
|
||
|
|
}
|
||
|
|
|
||
|
|
- rc = grub_linuxefi_secure_validate (kernel, filelen);
|
||
|
|
- if (rc < 0)
|
||
|
|
+ if (grub_efi_secure_boot ())
|
||
|
|
{
|
||
|
|
- grub_error (GRUB_ERR_INVALID_COMMAND, N_("%s has invalid signature"),
|
||
|
|
- argv[0]);
|
||
|
|
- goto fail;
|
||
|
|
+ rc = grub_linuxefi_secure_validate (kernel, filelen);
|
||
|
|
+ if (rc <= 0)
|
||
|
|
+ {
|
||
|
|
+ grub_error (GRUB_ERR_INVALID_COMMAND,
|
||
|
|
+ N_("%s has invalid signature"), argv[0]);
|
||
|
|
+ goto fail;
|
||
|
|
+ }
|
||
|
|
}
|
||
|
|
|
||
|
|
params = grub_efi_allocate_pages_max (0x3fffffff,
|
||
|
|
--
|
||
|
|
2.26.2
|
||
|
|
|