[PATCH] efi: Do not import certificates from UEFI Secure Boot for T2 Macs

[Matthew Garrett]

On Fri, Feb 11, 2022 at 04:51:22AM +0000, Aditya Garg wrote:

> With this patch, I built 2 kernels, one with CONFIG_LOAD_UEFI_KEYS=y and other with CONFIG_LOAD_UEFI_KEYS=n. I have got different variables causing panics in both cases. The logs couldn't get saved in journalctl so, I clicked a picture of the same. The kernel anyways was refusing to boot after these logs.

Oh gosh I'm an idiot. Please try this one instead.

diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index f3e54f6616f0..79a003c2f7b6 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -32,6 +32,8 @@
 #include <linux/stringify.h>
 #include <linux/workqueue.h>
 #include <linux/completion.h>
+#include <linux/ucs2_string.h>
+#include <linux/slab.h>
 
 #include <asm/efi.h>
 
@@ -179,6 +181,9 @@ static void efi_call_rts(struct work_struct *work)
 {
 	void *arg1, *arg2, *arg3, *arg4, *arg5;
 	efi_status_t status = EFI_NOT_FOUND;
+	unsigned long utf8_name_size;
+	char *utf8_name;
+	char guid_str[UUID_STRING_LEN + 1];
 
 	arg1 = efi_rts_work.arg1;
 	arg2 = efi_rts_work.arg2;
@@ -203,6 +208,17 @@ static void efi_call_rts(struct work_struct *work)
 				       (efi_time_t *)arg2);
 		break;
 	case EFI_GET_VARIABLE:
+		utf8_name_size = ucs2_utf8size((efi_char16_t *)arg1);
+		utf8_name = kmalloc(utf8_name_size+1, GFP_KERNEL);
+		if (!utf8_name) {
+			printk(KERN_INFO "failed to allocate UTF8 buffer\n");
+			break;
+		}
+
+		ucs2_as_utf8(utf8_name, (efi_char16_t *)arg1, utf8_name_size + 1);
+		efi_guid_to_str((efi_guid_t *)arg2, guid_str);
+
+		printk(KERN_INFO "Reading EFI variable %s-%s\n", utf8_name, guid_str);
 		status = efi_call_virt(get_variable, (efi_char16_t *)arg1,
 				       (efi_guid_t *)arg2, (u32 *)arg3,
 				       (unsigned long *)arg4, (void *)arg5);