[RFC PATCH v3 9/9] mkeficapsule: Add support for generating empty capsules

Sughosh Ganu sughosh.ganu at linaro.org
Wed Jan 19 19:55:48 CET 2022


The Dependable Boot specification describes the structure of the
firmware accept and revert capsules. These are empty capsules which
are used for signalling the acceptance or rejection of the updated
firmware by the OS. Add support for generating these empty capsules.

Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
---

Changes since V2:
* New patch for generating empty capsules

 tools/eficapsule.h   |   8 ++++
 tools/mkeficapsule.c | 102 ++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 100 insertions(+), 10 deletions(-)

diff --git a/tools/eficapsule.h b/tools/eficapsule.h
index 8c1560bb06..6001952bdc 100644
--- a/tools/eficapsule.h
+++ b/tools/eficapsule.h
@@ -50,6 +50,14 @@ typedef struct {
 	EFI_GUID(0x4aafd29d, 0x68df, 0x49ee, 0x8a, 0xa9, \
 		 0x34, 0x7d, 0x37, 0x56, 0x65, 0xa7)
 
+#define FW_ACCEPT_OS_GUID \
+	EFI_GUID(0x0c996046, 0xbcc0, 0x4d04, 0x85, 0xec, \
+		 0xe1, 0xfc, 0xed, 0xf1, 0xc6, 0xf8)
+
+#define FW_REVERT_OS_GUID \
+	EFI_GUID(0xacd58b4b, 0xc0e8, 0x475f, 0x99, 0xb5, \
+		 0x6b, 0x3f, 0x7e, 0x07, 0xaa, 0xf0)
+
 /* flags */
 #define CAPSULE_FLAGS_PERSIST_ACROSS_RESET      0x00010000
 
diff --git a/tools/mkeficapsule.c b/tools/mkeficapsule.c
index 161affdd15..643da3849d 100644
--- a/tools/mkeficapsule.c
+++ b/tools/mkeficapsule.c
@@ -29,6 +29,7 @@
 #include "eficapsule.h"
 
 static const char *tool_name = "mkeficapsule";
+static unsigned char empty_capsule;
 
 efi_guid_t efi_guid_fm_capsule = EFI_FIRMWARE_MANAGEMENT_CAPSULE_ID_GUID;
 efi_guid_t efi_guid_image_type_uboot_fit =
@@ -38,9 +39,9 @@ efi_guid_t efi_guid_image_type_uboot_raw =
 efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID;
 
 #ifdef CONFIG_TOOLS_LIBCRYPTO
-static const char *opts_short = "frg:i:I:v:p:c:m:dh";
+static const char *opts_short = "frg:i:I:v:p:c:m:dhAR";
 #else
-static const char *opts_short = "frg:i:I:v:h";
+static const char *opts_short = "frg:i:I:v:hAR";
 #endif
 
 static struct option options[] = {
@@ -55,15 +56,23 @@ static struct option options[] = {
 	{"monotonic-count", required_argument, NULL, 'm'},
 	{"dump-sig", no_argument, NULL, 'd'},
 #endif
+	{"fw-accept", no_argument, NULL, 'A'},
+	{"fw-revert", no_argument, NULL, 'R'},
 	{"help", no_argument, NULL, 'h'},
 	{NULL, 0, NULL, 0},
 };
 
 static void print_usage(void)
 {
-	fprintf(stderr, "Usage: %s [options] <image blob> <output file>\n"
-		"Options:\n"
+	if (empty_capsule) {
+		fprintf(stderr, "Usage: %s [options]  <output file>\n",
+			tool_name);
+	} else {
+		fprintf(stderr, "Usage: %s [options] <image blob> <output file>\n",
+			tool_name);
+	}
 
+	fprintf(stderr, "Options:\n"
 		"\t-f, --fit                   FIT image type\n"
 		"\t-r, --raw                   raw image type\n"
 		"\t-g, --guid <guid string>    guid for image blob type\n"
@@ -75,8 +84,9 @@ static void print_usage(void)
 		"\t-m, --monotonic-count <count>     monotonic count\n"
 		"\t-d, --dump_sig              dump signature (*.p7)\n"
 #endif
-		"\t-h, --help                  print a help message\n",
-		tool_name);
+	       "\t-A, --fw-accept          firmware accept capsule\n"
+	       "\t-R, --fw-revert          firmware revert capsule\n"
+	       "\t-h, --help                  print a help message\n");
 }
 
 /**
@@ -598,6 +608,59 @@ void convert_uuid_to_guid(unsigned char *buf)
 	buf[7] = c;
 }
 
+static int create_empty_capsule(char *path, efi_guid_t *guid, bool fw_accept)
+{
+	struct efi_capsule_header header;
+	FILE *f;
+	int ret;
+	efi_guid_t fw_accept_guid = FW_ACCEPT_OS_GUID;
+	efi_guid_t fw_revert_guid = FW_REVERT_OS_GUID;
+	efi_guid_t payload, capsule_guid;
+
+	f = NULL;
+	ret = -1;
+
+	f = fopen(path, "w");
+	if (!f) {
+		printf("cannot open %s\n", path);
+		goto err;
+	}
+
+	if (fw_accept)
+		capsule_guid = fw_accept_guid;
+	else
+		capsule_guid = fw_revert_guid;
+
+	memcpy(&header.capsule_guid, &capsule_guid, sizeof(efi_guid_t));
+	header.header_size = sizeof(header);
+	header.flags = 0;
+
+	if (fw_accept) {
+		header.capsule_image_size = sizeof(header) + sizeof(efi_guid_t);
+	} else {
+		header.capsule_image_size = sizeof(header);
+	}
+
+	if (write_capsule_file(f, &header, sizeof(header),
+			       "Capsule header"))
+		goto err;
+
+	if (fw_accept) {
+		memcpy(&payload, guid, sizeof(efi_guid_t));
+		if (write_capsule_file(f, &payload, sizeof(payload),
+				       "FW Accept Capsule Payload"))
+			goto err;
+	}
+
+	ret = 0;
+
+err:
+	if (f)
+		fclose(f);
+
+	return ret;
+}
+
 /**
  * main - main entry function of mkeficapsule
  * @argc:	Number of arguments
@@ -616,6 +679,7 @@ int main(int argc, char **argv)
 	unsigned char uuid_buf[16];
 	unsigned long index, instance;
 	uint64_t mcount;
+	unsigned char accept_fw_capsule, revert_fw_capsule;
 	char *privkey_file, *cert_file;
 	int c, idx;
 
@@ -625,6 +689,8 @@ int main(int argc, char **argv)
 	mcount = 0;
 	privkey_file = NULL;
 	cert_file = NULL;
+	accept_fw_capsule = 0;
+	revert_fw_capsule = 0;
 	dump_sig = 0;
 	for (;;) {
 		c = getopt_long(argc, argv, opts_short, options, &idx);
@@ -691,22 +757,38 @@ int main(int argc, char **argv)
 			dump_sig = 1;
 			break;
 #endif /* CONFIG_TOOLS_LIBCRYPTO */
+		case 'A':
+			accept_fw_capsule = 1;
+			break;
+		case 'R':
+			revert_fw_capsule = 1;
+			break;
 		case 'h':
 			print_usage();
 			exit(EXIT_SUCCESS);
 		}
 	}
 
+	empty_capsule = (accept_fw_capsule || revert_fw_capsule);
+
 	/* check necessary parameters */
-	if ((argc != optind + 2) || !guid ||
-	    ((privkey_file && !cert_file) ||
+	if ((!empty_capsule && argc != optind + 2) ||
+	    (empty_capsule && argc != optind + 1) ||
+	    (!revert_fw_capsule && !guid) || ((privkey_file && !cert_file) ||
 	     (!privkey_file && cert_file))) {
 		print_usage();
 		exit(EXIT_FAILURE);
 	}
 
-	if (create_fwbin(argv[argc - 1], argv[argc - 2], guid, index, instance,
-			 mcount, privkey_file, cert_file) < 0) {
+	if (empty_capsule) {
+		if (create_empty_capsule(argv[argc - 1], guid,
+					 accept_fw_capsule ? 1 : 0) < 0) {
+			printf("Creating empty capsule failed\n");
+			exit(EXIT_FAILURE);
+		}
+	} else 	if (create_fwbin(argv[argc - 1], argv[argc - 2], guid,
+				 index, instance, mcount, privkey_file,
+				 cert_file) < 0) {
 		fprintf(stderr, "Creating firmware capsule failed\n");
 		exit(EXIT_FAILURE);
 	}
-- 
2.17.1



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