[PATCH v2 06/10] platform/x86/intel/ifs: Authenticate and copy to secured memory

Jithu Joseph
2022-04-07T19:14:53Z

The IFS image contains hashes that will be used to authenticate the ifs
test chunks. First, use WRMSR to copy the hashes and enumerate the number
of test chunks, chunk size and the maximum number of cores that can run
scan test simultaneously.

Next, use WRMSR to authenticate each and every scan test chunk which is
also stored in the IFS image. The CPU will check if the test chunks match
the hashes, otherwise failure is indicated to system software. If the test
chunk is authenticated, it is automatically copied to secured memory.

The ifs hash copy and authentication only needs to be done on the first
logical cpu of each socket.

Reviewed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
---
drivers/platform/x86/intel/ifs/ifs.h | 33 ++++++
drivers/platform/x86/intel/ifs/load.c | 142 ++++++++++++++++++++++++++
2 files changed, 175 insertions(+)

diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h
index e1c9c16cbadb..4d12f8e71c67 100644
--- a/drivers/platform/x86/intel/ifs/ifs.h
+++ b/drivers/platform/x86/intel/ifs/ifs.h
@@ -10,13 +10,46 @@

#define IFS_BLOB_REV_ERR_INJ BIT(30)
#define IFS_BLOB_REV_DEBUG BIT(31)
+#define MSR_COPY_SCAN_HASHES 0x000002c2
+#define MSR_SCAN_HASHES_STATUS 0x000002c3
+#define MSR_AUTHENTICATE_AND_COPY_CHUNK 0x000002c4
+#define MSR_CHUNKS_AUTHENTICATION_STATUS 0x000002c5
+
+/* MSR_SCAN_HASHES_STATUS bit fields */
+union ifs_scan_hashes_status {
+ u64 data;
+ struct {
+ u64 chunk_size :16;
+ u64 num_chunks :8;
+ u64 rsvd1 :8;
+ u64 error_code :8;
+ u64 rsvd2 :11;
+ u64 max_core_limit :12;
+ u64 valid :1;
+ };
+};
+
+/* MSR_CHUNKS_AUTH_STATUS bit fields */
+union ifs_chunks_auth_status {
+ u64 data;
+ struct {
+ u64 valid_chunks :8;
+ u64 total_chunks :8;
+ u64 rsvd1 :16;
+ u64 error_code :8;
+ u64 rsvd2 :24;
+ };
+};
+
/**
* struct ifs_binary - attributes related to test binary
* @loaded_version: stores the currently loaded ifs image version.
+ * @valid_chunks: number of chunks which could be validated.
* @loaded: If a valid test binary has been loaded into the memory
*/
struct ifs_binary {
int loaded_version;
+ int valid_chunks;
bool loaded;
};

diff --git a/drivers/platform/x86/intel/ifs/load.c b/drivers/platform/x86/intel/ifs/load.c
index 8f2735775f5b..8778be87fee6 100644
--- a/drivers/platform/x86/intel/ifs/load.c
+++ b/drivers/platform/x86/intel/ifs/load.c
@@ -3,10 +3,13 @@

#include <linux/firmware.h>
#include <linux/platform_device.h>
+#include <linux/slab.h>
#include <asm/microcode_intel.h>

#include "ifs.h"
+
static const char *ifs_path = "intel/ifs/";
+static bool ifs_loading_error; /* error occurred during ifs hashes/chunk authentication.*/

struct ifs_header {
u32 header_ver;
@@ -25,6 +28,144 @@ struct ifs_header {
#define IFS_HEADER_SIZE (sizeof(struct ifs_header))
static struct ifs_header *ifs_header_ptr; /* pointer to the ifs image header */
static u64 ifs_hash_ptr; /* Address of ifs metadata (hash) */
+static u64 ifs_test_image_ptr; /* 256B aligned address of test pattern */
+
+static const char * const scan_hash_status[] = {
+ "Reserved",
+ "Attempt to copy scan hashes when copy already in progress",
+ "Secure Memory not set up correctly",
+ "FuSaInfo.ProgramID does not match or ff-mm-ss does not match",
+ "Reserved",
+ "Integrity check failed",
+ "Scan test is in progress"
+};
+
+static const char * const scan_authentication_status[] = {
+ "No error reported",
+ "Attempt to authenticate a chunk which is already marked as authentic",
+ "Chunk authentication error. The hash of chunk did not match expected value"
+};
+
+/*
+ * To copy scan hashes and authenticate test chunks, the initiating cpu must point
+ * to the EDX:EAX to the test image in linear address.
+ * Run wrmsr(MSR_COPY_SCAN_HASHES) for scan hash copy and run wrmsr(MSR_AUTHENTICATE_AND_COPY_CHUNK)
+ * for scan hash copy and test chunk authentication.
+ */
+static int copy_hashes_authenticate_chunks(void *arg)
+{
+ union ifs_scan_hashes_status hashes_status;
+ union ifs_chunks_auth_status chunk_status;
+ int i, num_chunks, chunk_size;
+ u64 linear_addr, base;
+ u32 err_code;
+
+ /* run scan hash copy */
+ wrmsrl(MSR_COPY_SCAN_HASHES, ifs_hash_ptr);
+ rdmsrl(MSR_SCAN_HASHES_STATUS, hashes_status.data);
+
+ /* enumerate the scan image information */
+ num_chunks = hashes_status.num_chunks;
+ chunk_size = hashes_status.chunk_size * 1024;
+ err_code = hashes_status.error_code;
+
+ if (!hashes_status.valid) {
+ ifs_loading_error = true;
+ if (err_code >= ARRAY_SIZE(scan_hash_status)) {
+ dev_err(&ifs_pdev->dev,
+ "invalid error code 0x%x for hash copy\n", err_code);
+ return -EINVAL;
+ }
+ dev_err(&ifs_pdev->dev, "Hash copy error : %s", scan_hash_status[err_code]);
+ return -ENODEV;
+ }
+ dev_info(&ifs_pdev->dev, "the total chunk number: %d\n", num_chunks);
+
+ /* base linear address to the scan data */
+ base = ifs_test_image_ptr;
+
+ /* scan data authentication and copy chunks to secured memory */
+ for (i = 0; i < num_chunks; i++) {
+ linear_addr = base + i * chunk_size;
+ linear_addr |= i;
+
+ wrmsrl(MSR_AUTHENTICATE_AND_COPY_CHUNK, linear_addr);
+ rdmsrl(MSR_CHUNKS_AUTHENTICATION_STATUS, chunk_status.data);
+
+ ifs_binary.valid_chunks = chunk_status.valid_chunks;
+ err_code = chunk_status.error_code;
+
+ if (err_code) {
+ ifs_loading_error = true;
+ if (err_code >= ARRAY_SIZE(scan_authentication_status)) {
+ dev_err(&ifs_pdev->dev,
+ "invalid error code 0x%x for authentication\n", err_code);
+ return -EINVAL;
+ }
+ dev_err(&ifs_pdev->dev, "Chunk authentication error %s\n",
+ scan_authentication_status[err_code]);
+ return -ENODEV;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * IFS requires scan chunks authenticated per each socket in the platform.
+ * Once the test chunk is authenticated, it is automatically copied to secured memory
+ * and proceed the authentication for the next chunk.
+ */
+static int scan_chunks_sanity_check(void)
+{
+ int metadata_size, curr_pkg, cpu, ret = -ENOMEM;
+ bool *package_authenticated;
+ char *test_ptr;
+
+ package_authenticated = kcalloc(topology_max_packages(), sizeof(bool), GFP_KERNEL);
+ if (!package_authenticated)
+ return ret;
+
+ metadata_size = ifs_header_ptr->metadata_size;
+
+ /* Spec says that if the Meta Data Size = 0 then it should be treated as 2000 */
+ if (metadata_size == 0)
+ metadata_size = 2000;
+
+ /* Scan chunk start must be 256 byte aligned */
+ if ((metadata_size + IFS_HEADER_SIZE) % 256) {
+ dev_err(&ifs_pdev->dev,
+ "Scan pattern offset within the binary is not 256 byte aligned\n");
+ return -EINVAL;
+ }
+
+ test_ptr = (char *)ifs_header_ptr + IFS_HEADER_SIZE + metadata_size;
+
+ ifs_test_image_ptr = (u64)test_ptr;
+ ifs_binary.loaded_version = ifs_header_ptr->blob_revision;
+
+ /* copy the scan hash and authenticate per package */
+ cpus_read_lock();
+ for_each_online_cpu(cpu) {
+ curr_pkg = topology_physical_package_id(cpu);
+ if (package_authenticated[curr_pkg])
+ continue;
+ package_authenticated[curr_pkg] = 1;
+ ret = smp_call_function_single(cpu, (void *)copy_hashes_authenticate_chunks,
+ NULL, 1);
+ if (ret || ifs_loading_error) {
+ ret = ifs_loading_error ? -ENOMEM : ret;
+ goto out;
+ }
+ }
+
+out:
+ cpus_read_unlock();
+ kfree(package_authenticated);
+
+ return ret;
+}
+
static int ifs_sanity_check(void *mc)
{
struct microcode_header_intel *mc_header = mc;
@@ -137,6 +278,7 @@ int load_ifs_binary(void)
ifs_hash_ptr = (u64)(ifs_header_ptr + 1);

check_binary_flags(ifs_header_ptr);
+ ret = scan_chunks_sanity_check();
release_firmware(scan_fw);

return ret;
--
2.17.1