[PATCH v4 1/2] treewide: Add a flag to detect the Apple T2 chip

[Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>]

Add a flag to detect Apple T2 chips on Intel Macs.
Cache the result to avoid repeated checks. That will
be used in upcoming patches.

Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>
---
 arch/x86/kernel/quirks.c                      | 37 ++++++++++++++++++
 include/linux/platform_data/x86/apple.h       |  5 +++
 .../platform_certs/keyring_handler.h          |  8 ----
 security/integrity/platform_certs/load_uefi.c | 38 ++++---------------
 4 files changed, 50 insertions(+), 38 deletions(-)

diff --git a/arch/x86/kernel/quirks.c b/arch/x86/kernel/quirks.c
index a92f18db9610..6651e5d4d106 100644
--- a/arch/x86/kernel/quirks.c
+++ b/arch/x86/kernel/quirks.c
@@ -664,8 +664,45 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2083, quirk_intel_purley_xeon_ras
 bool x86_apple_machine;
 EXPORT_SYMBOL(x86_apple_machine);
 
+bool has_apple_t2_chip;
+EXPORT_SYMBOL(has_apple_t2_chip);
+
+static const char * const __initconst apple_t2_models[] = {
+	"MacBookPro15,1",
+	"MacBookPro15,2",
+	"MacBookPro15,3",
+	"MacBookPro15,4",
+	"MacBookPro16,1",
+	"MacBookPro16,2",
+	"MacBookPro16,3",
+	"MacBookPro16,4",
+	"MacBookAir8,1",
+	"MacBookAir8,2",
+	"MacBookAir9,1",
+	"Macmini8,1",
+	"MacPro7,1",
+	"iMac20,1",
+	"iMac20,2",
+	"iMacPro1,1",
+};
+
 void __init early_platform_quirks(void)
 {
 	x86_apple_machine = dmi_match(DMI_SYS_VENDOR, "Apple Inc.") ||
 			    dmi_match(DMI_SYS_VENDOR, "Apple Computer, Inc.");
+
+	if (x86_apple_machine) {
+		const char *product_name = dmi_get_system_info(DMI_PRODUCT_NAME);
+		int i;
+
+		if (!product_name)
+			return;
+
+		for (i = 0; i < ARRAY_SIZE(apple_t2_models); i++) {
+			if (!strcmp(product_name, apple_t2_models[i])) {
+				has_apple_t2_chip = true;
+				break;
+			}
+		}
+	}
 }
diff --git a/include/linux/platform_data/x86/apple.h b/include/linux/platform_data/x86/apple.h
index 079e816c3c21..47b27dceab18 100644
--- a/include/linux/platform_data/x86/apple.h
+++ b/include/linux/platform_data/x86/apple.h
@@ -6,8 +6,13 @@
  * x86_apple_machine - whether the machine is an x86 Apple Macintosh
  */
 extern bool x86_apple_machine;
+/**
+ * has_apple_t2_chip - whether the machine has the Apple T2 chip
+ */
+extern bool has_apple_t2_chip;
 #else
 #define x86_apple_machine false
+#define has_apple_t2_chip false
 #endif
 
 #endif
diff --git a/security/integrity/platform_certs/keyring_handler.h b/security/integrity/platform_certs/keyring_handler.h
index f92895cc50f6..a355f4400179 100644
--- a/security/integrity/platform_certs/keyring_handler.h
+++ b/security/integrity/platform_certs/keyring_handler.h
@@ -45,11 +45,3 @@ efi_element_handler_t get_handler_for_code_signing_keys(const efi_guid_t *sig_ty
 efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type);
 
 #endif
-
-#ifndef UEFI_QUIRK_SKIP_CERT
-#define UEFI_QUIRK_SKIP_CERT(vendor, product) \
-		 .matches = { \
-			DMI_MATCH(DMI_BOARD_VENDOR, vendor), \
-			DMI_MATCH(DMI_PRODUCT_NAME, product), \
-		},
-#endif
diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
index c0d6948446c3..b4096d4c828d 100644
--- a/security/integrity/platform_certs/load_uefi.c
+++ b/security/integrity/platform_certs/load_uefi.c
@@ -3,42 +3,16 @@
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/cred.h>
-#include <linux/dmi.h>
 #include <linux/err.h>
 #include <linux/efi.h>
 #include <linux/slab.h>
 #include <linux/ima.h>
+#include <linux/platform_data/x86/apple.h>
 #include <keys/asymmetric-type.h>
 #include <keys/system_keyring.h>
 #include "../integrity.h"
 #include "keyring_handler.h"
 
-/*
- * On T2 Macs reading the db and dbx efi variables to load UEFI Secure Boot
- * certificates causes occurrence of a page fault in Apple's firmware and
- * a crash disabling EFI runtime services. The following quirk skips reading
- * these variables.
- */
-static const struct dmi_system_id uefi_skip_cert[] = {
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,2") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,3") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,4") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,2") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,3") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,4") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,2") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir9,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "Macmini8,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacPro7,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,2") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMacPro1,1") },
-	{ }
-};
-
 /*
  * Look to see if a UEFI variable called MokIgnoreDB exists and return true if
  * it does.
@@ -165,10 +139,14 @@ static int __init load_uefi_certs(void)
 	unsigned long dbsize = 0, dbxsize = 0, mokxsize = 0;
 	efi_status_t status;
 	int rc = 0;
-	const struct dmi_system_id *dmi_id;
 
-	dmi_id = dmi_first_match(uefi_skip_cert);
-	if (dmi_id) {
+	/*
+	 * On T2 Macs reading the db and dbx efi variables to load UEFI Secure Boot
+	 * certificates causes occurrence of a page fault in Apple's firmware and
+	 * a crash disabling EFI runtime services. The following quirk skips reading
+	 * these variables.
+	 */
+	if (has_apple_t2_chip) {
 		pr_err("Reading UEFI Secure Boot Certs is not supported on T2 Macs.\n");
 		return false;
 	}
-- 
2.43.0