[PATCH 3/4] tools: add fdtsig command

AKASHI Takahiro
2021-05-12T04:57:52Z

This command allows us to add a certificate (or public key) to dtb blob:
{
signature {
capsule-key = "...";
};
}

The value is actually a signature list in terms of UEFI specificaion,
and used in verifying UEFI capsules.

The code was originally developed by Sughosh and derived from
mkeficapsule.c.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
Makefile | 2 +-
tools/Makefile | 2 +
tools/fdtsig.c | 274 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 277 insertions(+), 1 deletion(-)
create mode 100644 tools/fdtsig.c

diff --git a/Makefile b/Makefile
index 9806464357e0..8b40987234a0 100644
--- a/Makefile
+++ b/Makefile
@@ -1016,7 +1016,7 @@ quiet_cmd_lzma = LZMA $@
cmd_lzma = lzma -c -z -k -9 $< > $@

quiet_cmd_fdtsig = FDTSIG $@
-cmd_fdtsig = $(srctree)/tools/fdtsig.sh $(CONFIG_EFI_PKEY_FILE) $@
+cmd_fdtsig = $(objtree)/tools/fdtsig -K $(CONFIG_EFI_PKEY_FILE) -D $@

cfg: u-boot.cfg

diff --git a/tools/Makefile b/tools/Makefile
index 71a52719620c..e6fd1dbade19 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -234,6 +234,8 @@ HOSTCFLAGS_asn1_compiler.o = -idirafter $(srctree)/include
ifneq ($(CONFIG_EFI_CAPSULE_AUTHENTICATE),)
HOSTLDLIBS_mkeficapsule += \
$(shell pkg-config --libs libssl libcrypto 2> /dev/null || echo "-lssl -lcrypto")
+ fdtsig-objs := fdtsig.o $(LIBFDT_OBJS)
+ hostprogs-y += fdtsig
endif
hostprogs-$(CONFIG_EFI_HAVE_CAPSULE_SUPPORT) += mkeficapsule

diff --git a/tools/fdtsig.c b/tools/fdtsig.c
new file mode 100644
index 000000000000..daa1e63c3b33
--- /dev/null
+++ b/tools/fdtsig.c
@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2021 Linaro Limited
+ * The code in this file was extracted from mkeficapsule.c
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <malloc.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#include <linux/libfdt.h>
+
+#define SIGNATURE_NODENAME "signature"
+#define OVERLAY_NODENAME "__overlay__"
+
+static const char *tool_name = "fdtsig";
+
+static const char *opts_short = "D:K:Oh";
+
+static struct option options[] = {
+ {"dtb", required_argument, NULL, 'D'},
+ {"public key", required_argument, NULL, 'K'},
+ {"overlay", no_argument, NULL, 'O'},
+ {"help", no_argument, NULL, 'h'},
+ {NULL, 0, NULL, 0},
+};
+
+static void print_usage(void)
+{
+ printf("Usage: %s [options]\n"
+ "Options:\n"
+
+ "\t-K, --public-key <key file> public key esl file\n"
+ "\t-D, --dtb <dtb file> dtb file\n"
+ "\t-O, --overlay the dtb file is an overlay\n"
+ "\t-h, --help print a help message\n",
+ tool_name);
+}
+
+static int fdt_add_pub_key_data(void *sptr, void *dptr, size_t key_size,
+ bool overlay)
+{
+ int parent;
+ int ov_node;
+ int frag_node;
+ int ret = 0;
+
+ if (overlay) {
+ /*
+ * The signature would be stored in the
+ * first fragment node of the overlay
+ */
+ frag_node = fdt_first_subnode(dptr, 0);
+ if (frag_node == -FDT_ERR_NOTFOUND) {
+ fprintf(stderr,
+ "Couldn't find the fragment node: %s\n",
+ fdt_strerror(frag_node));
+ goto done;
+ }
+
+ ov_node = fdt_subnode_offset(dptr, frag_node, OVERLAY_NODENAME);
+ if (ov_node == -FDT_ERR_NOTFOUND) {
+ fprintf(stderr,
+ "Couldn't find the __overlay__ node: %s\n",
+ fdt_strerror(ov_node));
+ goto done;
+ }
+ } else {
+ ov_node = 0;
+ }
+
+ parent = fdt_subnode_offset(dptr, ov_node, SIGNATURE_NODENAME);
+ if (parent == -FDT_ERR_NOTFOUND) {
+ parent = fdt_add_subnode(dptr, ov_node, SIGNATURE_NODENAME);
+ if (parent < 0) {
+ ret = parent;
+ if (ret != -FDT_ERR_NOSPACE) {
+ fprintf(stderr,
+ "Couldn't create signature node: %s\n",
+ fdt_strerror(parent));
+ }
+ }
+ }
+ if (ret)
+ goto done;
+
+ /* Write the key to the FDT node */
+ ret = fdt_setprop(dptr, parent, "capsule-key",
+ sptr, key_size);
+
+done:
+ if (ret)
+ ret = ret == -FDT_ERR_NOSPACE ? -ENOSPC : -EIO;
+
+ return ret;
+}
+
+static int add_public_key(const char *pkey_file, const char *dtb_file,
+ bool overlay)
+{
+ int ret;
+ int srcfd = -1;
+ int destfd = -1;
+ void *sptr = NULL;
+ void *dptr = NULL;
+ off_t src_size;
+ struct stat pub_key;
+ struct stat dtb;
+
+ /* Find out the size of the public key */
+ srcfd = open(pkey_file, O_RDONLY);
+ if (srcfd == -1) {
+ fprintf(stderr, "%s: Can't open %s: %s\n",
+ __func__, pkey_file, strerror(errno));
+ ret = -1;
+ goto err;
+ }
+
+ ret = fstat(srcfd, &pub_key);
+ if (ret == -1) {
+ fprintf(stderr, "%s: Can't stat %s: %s\n",
+ __func__, pkey_file, strerror(errno));
+ ret = -1;
+ goto err;
+ }
+
+ src_size = pub_key.st_size;
+
+ /* mmap the public key esl file */
+ sptr = mmap(0, src_size, PROT_READ, MAP_SHARED, srcfd, 0);
+ if (sptr == MAP_FAILED) {
+ fprintf(stderr, "%s: Failed to mmap %s:%s\n",
+ __func__, pkey_file, strerror(errno));
+ ret = -1;
+ goto err;
+ }
+
+ /* Open the dest FDT */
+ destfd = open(dtb_file, O_RDWR);
+ if (destfd == -1) {
+ fprintf(stderr, "%s: Can't open %s: %s\n",
+ __func__, dtb_file, strerror(errno));
+ ret = -1;
+ goto err;
+ }
+
+ ret = fstat(destfd, &dtb);
+ if (ret == -1) {
+ fprintf(stderr, "%s: Can't stat %s: %s\n",
+ __func__, dtb_file, strerror(errno));
+ goto err;
+ }
+
+ dtb.st_size += src_size + 0x30;
+ if (ftruncate(destfd, dtb.st_size)) {
+ fprintf(stderr, "%s: Can't expand %s: %s\n",
+ __func__, dtb_file, strerror(errno));
+ ret = -1;
+ goto err;
+ }
+
+ errno = 0;
+ /* mmap the dtb file */
+ dptr = mmap(0, dtb.st_size, PROT_READ | PROT_WRITE, MAP_SHARED,
+ destfd, 0);
+ if (dptr == MAP_FAILED) {
+ fprintf(stderr, "%s: Failed to mmap %s:%s\n",
+ __func__, dtb_file, strerror(errno));
+ ret = -1;
+ goto err;
+ }
+
+ if (fdt_check_header(dptr)) {
+ fprintf(stderr, "%s: Invalid FDT header\n", __func__);
+ ret = -1;
+ goto err;
+ }
+
+ ret = fdt_open_into(dptr, dptr, dtb.st_size);
+ if (ret) {
+ fprintf(stderr, "%s: Cannot expand FDT: %s\n",
+ __func__, fdt_strerror(ret));
+ ret = -1;
+ goto err;
+ }
+
+ /* Copy the esl file to the expanded FDT */
+ ret = fdt_add_pub_key_data(sptr, dptr, src_size, overlay);
+ if (ret < 0) {
+ fprintf(stderr, "%s: Unable to add public key to the FDT\n",
+ __func__);
+ ret = -1;
+ goto err;
+ }
+
+ ret = 0;
+
+err:
+ if (sptr)
+ munmap(sptr, src_size);
+
+ if (dptr)
+ munmap(dptr, dtb.st_size);
+
+ if (srcfd != -1)
+ close(srcfd);
+
+ if (destfd != -1)
+ close(destfd);
+
+ return ret;
+}
+
+int main(int argc, char **argv)
+{
+ char *pkey_file;
+ char *dtb_file;
+ bool overlay;
+ int c, idx, ret;
+
+ pkey_file = NULL;
+ dtb_file = NULL;
+ overlay = false;
+
+ for (;;) {
+ c = getopt_long(argc, argv, opts_short, options, &idx);
+ if (c == -1)
+ break;
+
+ switch (c) {
+ case 'K':
+ if (pkey_file) {
+ printf("Public Key already specified\n");
+ return -1;
+ }
+ pkey_file = optarg;
+ break;
+ case 'D':
+ if (dtb_file) {
+ printf("DTB file already specified\n");
+ return -1;
+ }
+ dtb_file = optarg;
+ break;
+ case 'O':
+ overlay = true;
+ break;
+ case 'h':
+ print_usage();
+ return 0;
+ }
+ }
+
+ /* check necessary parameters */
+ if (!pkey_file || !dtb_file) {
+ print_usage();
+ exit(EXIT_FAILURE);
+ }
+
+ ret = add_public_key(pkey_file, dtb_file, overlay);
+ if (ret == -1) {
+ printf("Adding public key to the dtb failed\n");
+ exit(EXIT_FAILURE);
+ }
+
+ exit(EXIT_SUCCESS);
+}
--
2.31.0