linux-kernel - [PATCH 02/28] efi/x86: Add RNG seed EFI table to unencrypted mapping check

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Message-Id: <20200308080859.21568-3-ardb@kernel.org>
Date:   Sun,  8 Mar 2020 09:08:33 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ard Biesheuvel <ardb@...nel.org>, linux-kernel@...r.kernel.org,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Christoph Hellwig <hch@....de>,
        David Hildenbrand <david@...hat.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Guenter Roeck <linux@...ck-us.net>,
        Heinrich Schuchardt <xypron.glpk@....de>,
        Jonathan Corbet <corbet@....net>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nikolai Merinov <n.merinov@...ngo-systems.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Vladis Dronov <vdronov@...hat.com>
Subject: [PATCH 02/28] efi/x86: Add RNG seed EFI table to unencrypted mapping check

From: Tom Lendacky <thomas.lendacky@....com>

When booting with SME active, EFI tables must be mapped unencrypted since
they were built by UEFI in unencrypted memory. Update the list of tables
to be checked during early_memremap() processing to account for the EFI
RNG seed table.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Link: https://lore.kernel.org/r/b64385fc13e5d7ad4b459216524f138e7879234f.1582662842.git.thomas.lendacky@amd.com
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/platform/efi/efi.c |  1 +
 drivers/firmware/efi/efi.c  | 18 ++++++++++--------
 include/linux/efi.h         |  2 ++
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 3ce695501681..1aae5302501d 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -90,6 +90,7 @@ static const unsigned long * const efi_tables[] = {
 #endif
 	&efi.tpm_log,
 	&efi.tpm_final_log,
+	&efi_rng_seed,
 };
 
 u64 efi_setup;		/* efi setup_data physical address */
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index f3dda0c82187..5f77cb8756ef 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -46,7 +46,7 @@ struct efi __read_mostly efi = {
 };
 EXPORT_SYMBOL(efi);
 
-static unsigned long __ro_after_init rng_seed = EFI_INVALID_TABLE_ADDR;
+unsigned long __ro_after_init efi_rng_seed = EFI_INVALID_TABLE_ADDR;
 static unsigned long __initdata mem_reserve = EFI_INVALID_TABLE_ADDR;
 static unsigned long __initdata rt_prop = EFI_INVALID_TABLE_ADDR;
 
@@ -508,7 +508,7 @@ static const efi_config_table_type_t common_tables[] __initconst = {
 	{SMBIOS3_TABLE_GUID, "SMBIOS 3.0", &efi.smbios3},
 	{EFI_SYSTEM_RESOURCE_TABLE_GUID, "ESRT", &efi.esrt},
 	{EFI_MEMORY_ATTRIBUTES_TABLE_GUID, "MEMATTR", &efi_mem_attr_table},
-	{LINUX_EFI_RANDOM_SEED_TABLE_GUID, "RNG", &rng_seed},
+	{LINUX_EFI_RANDOM_SEED_TABLE_GUID, "RNG", &efi_rng_seed},
 	{LINUX_EFI_TPM_EVENT_LOG_GUID, "TPMEventLog", &efi.tpm_log},
 	{LINUX_EFI_TPM_FINAL_LOG_GUID, "TPMFinalLog", &efi.tpm_final_log},
 	{LINUX_EFI_MEMRESERVE_TABLE_GUID, "MEMRESERVE", &mem_reserve},
@@ -576,11 +576,11 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
 	pr_cont("\n");
 	set_bit(EFI_CONFIG_TABLES, &efi.flags);
 
-	if (rng_seed != EFI_INVALID_TABLE_ADDR) {
+	if (efi_rng_seed != EFI_INVALID_TABLE_ADDR) {
 		struct linux_efi_random_seed *seed;
 		u32 size = 0;
 
-		seed = early_memremap(rng_seed, sizeof(*seed));
+		seed = early_memremap(efi_rng_seed, sizeof(*seed));
 		if (seed != NULL) {
 			size = seed->size;
 			early_memunmap(seed, sizeof(*seed));
@@ -588,7 +588,8 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
 			pr_err("Could not map UEFI random seed!\n");
 		}
 		if (size > 0) {
-			seed = early_memremap(rng_seed, sizeof(*seed) + size);
+			seed = early_memremap(efi_rng_seed,
+					      sizeof(*seed) + size);
 			if (seed != NULL) {
 				pr_notice("seeding entropy pool\n");
 				add_bootloader_randomness(seed->bits, seed->size);
@@ -980,7 +981,7 @@ static int update_efi_random_seed(struct notifier_block *nb,
 	if (!kexec_in_progress)
 		return NOTIFY_DONE;
 
-	seed = memremap(rng_seed, sizeof(*seed), MEMREMAP_WB);
+	seed = memremap(efi_rng_seed, sizeof(*seed), MEMREMAP_WB);
 	if (seed != NULL) {
 		size = min(seed->size, EFI_RANDOM_SEED_SIZE);
 		memunmap(seed);
@@ -988,7 +989,8 @@ static int update_efi_random_seed(struct notifier_block *nb,
 		pr_err("Could not map UEFI random seed!\n");
 	}
 	if (size > 0) {
-		seed = memremap(rng_seed, sizeof(*seed) + size, MEMREMAP_WB);
+		seed = memremap(efi_rng_seed, sizeof(*seed) + size,
+				MEMREMAP_WB);
 		if (seed != NULL) {
 			seed->size = size;
 			get_random_bytes(seed->bits, seed->size);
@@ -1006,7 +1008,7 @@ static struct notifier_block efi_random_seed_nb = {
 
 static int __init register_update_efi_random_seed(void)
 {
-	if (rng_seed == EFI_INVALID_TABLE_ADDR)
+	if (efi_rng_seed == EFI_INVALID_TABLE_ADDR)
 		return 0;
 	return register_reboot_notifier(&efi_random_seed_nb);
 }
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 08186e0f98f1..abfc98e4dfe1 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -526,6 +526,8 @@ typedef struct {
 	efi_time_t time_of_revocation;
 } efi_cert_x509_sha256_t;
 
+extern unsigned long __ro_after_init efi_rng_seed;		/* RNG Seed table */
+
 /*
  * All runtime access to EFI goes through this structure:
  */
-- 
2.17.1