linux-kernel - [PATCH v6 14/14] x86: EFI stub DRTM launch support for Secure Launch

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Message-Id: <20230504145023.835096-15-ross.philipson@oracle.com>
Date:   Thu,  4 May 2023 14:50:23 +0000
From:   Ross Philipson <ross.philipson@...cle.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-integrity@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-crypto@...r.kernel.org, iommu@...ts.linux-foundation.org,
        kexec@...ts.infradead.org, linux-efi@...r.kernel.org
Cc:     ross.philipson@...cle.com, dpsmith@...rtussolutions.com,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        ardb@...nel.org, mjg59@...f.ucam.org,
        James.Bottomley@...senpartnership.com, luto@...capital.net,
        nivedita@...m.mit.edu, kanth.ghatraju@...cle.com,
        trenchboot-devel@...glegroups.com
Subject: [PATCH v6 14/14] x86: EFI stub DRTM launch support for Secure Launch

This support allows the DRTM launch to be initiated after and EFI stub
launch of the Linux kernel is done. This is accomplished by providing
a handler to jump to when a Secure Launch is in progress.

Signed-off-by: Ross Philipson <ross.philipson@...cle.com>
---
 drivers/firmware/efi/libstub/x86-stub.c | 55 +++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
index a0bfd31..66ff922 100644
--- a/drivers/firmware/efi/libstub/x86-stub.c
+++ b/drivers/firmware/efi/libstub/x86-stub.c
@@ -9,6 +9,7 @@
 #include <linux/efi.h>
 #include <linux/pci.h>
 #include <linux/stddef.h>
+#include <linux/slr_table.h>
 
 #include <asm/efi.h>
 #include <asm/e820/types.h>
@@ -760,6 +761,57 @@ static efi_status_t exit_boot(struct boot_params *boot_params, void *handle)
 	return EFI_SUCCESS;
 }
 
+static void efi_secure_launch(struct boot_params *boot_params)
+{
+	struct slr_entry_uefi_config *uefi_config;
+	struct slr_uefi_cfg_entry *uefi_entry;
+	struct slr_entry_dl_info *dlinfo;
+	efi_guid_t guid = SLR_TABLE_GUID;
+	struct slr_table *slrt;
+	u64 memmap_hi;
+	void *table;
+	u8 buf[64] = {0};
+
+	table = get_efi_config_table(guid);
+
+	/*
+	 * The presence of this table indicated a Secure Launch
+	 * is being requested.
+	 */
+	if (!table)
+		return;
+
+	slrt = (struct slr_table *)table;
+
+	if (slrt->magic != SLR_TABLE_MAGIC)
+		return;
+
+	/* Add config information to measure the UEFI memory map */
+	uefi_config = (struct slr_entry_uefi_config *)buf;
+	uefi_config->hdr.tag = SLR_ENTRY_UEFI_CONFIG;
+	uefi_config->hdr.size = sizeof(*uefi_config) + sizeof(*uefi_entry);
+	uefi_config->revision = SLR_UEFI_CONFIG_REVISION;
+	uefi_config->nr_entries = 1;
+	uefi_entry = (struct slr_uefi_cfg_entry *)(buf + sizeof(*uefi_config));
+	uefi_entry->pcr = 18;
+	uefi_entry->cfg = boot_params->efi_info.efi_memmap;
+	memmap_hi = boot_params->efi_info.efi_memmap_hi;
+	uefi_entry->cfg |= memmap_hi << 32;
+	uefi_entry->size = boot_params->efi_info.efi_memmap_size;
+	memcpy(&uefi_entry->evt_info[0], "Measured UEFI memory map",
+		strlen("Measured UEFI memory map"));
+
+	if (slr_add_entry(slrt, (struct slr_entry_hdr *)uefi_config))
+		return;
+
+	/* Jump through DL stub to initiate Secure Launch */
+	dlinfo = (struct slr_entry_dl_info *)
+		slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_DL_INFO);
+
+	asm volatile ("jmp *%%rax"
+		      : : "a" (dlinfo->dl_handler), "D" (&dlinfo->bl_context));
+}
+
 /*
  * On success, we return the address of startup_32, which has potentially been
  * relocated by efi_relocate_kernel.
@@ -905,6 +957,9 @@ asmlinkage unsigned long efi_main(efi_handle_t handle,
 		goto fail;
 	}
 
+	/* If a secure launch is in progress, this never returns */
+	efi_secure_launch(boot_params);
+
 	return bzimage_addr;
 fail:
 	efi_err("efi_main() failed!\n");
-- 
1.8.3.1