89 lines
3.0 KiB
Diff
89 lines
3.0 KiB
Diff
From b01dc9aaedb5a5e91e2ca10748fce65406d657c0 Mon Sep 17 00:00:00 2001
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From: Fedora Ninjas <grub2-owner@fedoraproject.org>
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Date: Mon, 10 Aug 2020 14:54:34 +0800
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Subject: [PATCH 7/7] linuxefi: fail kernel validation without shim protocol.
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If certificates that signed grub are installed into db, grub can be
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booted directly. It will then boot any kernel without signature
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validation. The booted kernel will think it was booted in secureboot
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mode and will implement lockdown, yet it could have been tampered.
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This version of the patch skips calling verification, when booted
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without secureboot. And is indented with gnu ident.
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CVE-2020-15705
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Reported-by: Mathieu Trudel-Lapierre <cyphermox@ubuntu.com>
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Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
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Signed-off-by: Baogen Shang <baogen.shang@windriver.com.cn>
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---
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grub-core/loader/arm64/linux.c | 12 ++++++++----
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grub-core/loader/efi/linux.c | 1 +
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grub-core/loader/i386/efi/linux.c | 13 ++++++++-----
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3 files changed, 17 insertions(+), 9 deletions(-)
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diff --git a/grub-core/loader/arm64/linux.c b/grub-core/loader/arm64/linux.c
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index 8791b35..a18c487 100644
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--- a/grub-core/loader/arm64/linux.c
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+++ b/grub-core/loader/arm64/linux.c
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@@ -383,11 +383,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
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grub_dprintf ("linux", "kernel @ %p\n", kernel_addr);
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- rc = grub_linuxefi_secure_validate (kernel_addr, kernel_size);
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- if (rc < 0)
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+ if (grub_efi_secure_boot ())
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{
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- grub_error (GRUB_ERR_INVALID_COMMAND, N_("%s has invalid signature"), argv[0]);
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- goto fail;
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+ rc = grub_linuxefi_secure_validate (kernel_addr, kernel_size);
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+ if (rc <= 0)
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+ {
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+ grub_error (GRUB_ERR_INVALID_COMMAND,
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+ N_("%s has invalid signature"), argv[0]);
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+ goto fail;
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+ }
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}
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pe = (void *)((unsigned long)kernel_addr + lh.hdr_offset);
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diff --git a/grub-core/loader/efi/linux.c b/grub-core/loader/efi/linux.c
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index e09f824..927d89a 100644
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--- a/grub-core/loader/efi/linux.c
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+++ b/grub-core/loader/efi/linux.c
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@@ -33,6 +33,7 @@ struct grub_efi_shim_lock
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};
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typedef struct grub_efi_shim_lock grub_efi_shim_lock_t;
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+// Returns 1 on success, -1 on error, 0 when not available
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int
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grub_linuxefi_secure_validate (void *data, grub_uint32_t size)
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{
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diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c
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index e5b2736..e613115 100644
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--- a/grub-core/loader/i386/efi/linux.c
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+++ b/grub-core/loader/i386/efi/linux.c
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@@ -301,12 +301,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
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goto fail;
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}
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- rc = grub_linuxefi_secure_validate (kernel, filelen);
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- if (rc < 0)
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+ if (grub_efi_secure_boot ())
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{
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- grub_error (GRUB_ERR_INVALID_COMMAND, N_("%s has invalid signature"),
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- argv[0]);
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- goto fail;
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+ rc = grub_linuxefi_secure_validate (kernel, filelen);
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+ if (rc <= 0)
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+ {
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+ grub_error (GRUB_ERR_INVALID_COMMAND,
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+ N_("%s has invalid signature"), argv[0]);
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+ goto fail;
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+ }
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}
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lh = (struct linux_i386_kernel_header *)kernel;
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--
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1.8.3.1
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