tpm_extendpcr: Extend digests into a TPM PCR

2017-12-13 07:10:28 +01:00
parent 5d3eb57cfd
commit 0fb293fc91
7 changed files with 424 additions and 4 deletions
@@ -0,0 +1 @@
+tpm_extendpcr
@@ -0,0 +1,14 @@
+bin_PROGRAMS = tpm_extendpcr
+
+tpm_extendpcr_SOURCES = tpm_extendpcr.c
+
+tpm_extendpcr_LDADD = \
+	$(top_builddir)/src/libstrongswan/libstrongswan.la \
+	$(top_builddir)/src/libtpmtss/libtpmtss.la
+
+tpm_extendpcr.o :	$(top_builddir)/config.status
+
+AM_CPPFLAGS = \
+	-I$(top_srcdir)/src/libstrongswan \
+	-I$(top_srcdir)/src/libtpmtss \
+	-DIPSEC_CONFDIR=\"${sysconfdir}\"
@@ -0,0 +1,317 @@
+/*
+ * Copyright (C) 2017 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include <tpm_tss.h>
+
+#include <library.h>
+#include <crypto/hashers/hasher.h>
+#include <utils/debug.h>
+
+#include <syslog.h>
+#include <getopt.h>
+#include <errno.h>
+
+
+/* logging */
+static bool log_to_stderr = TRUE;
+static bool log_to_syslog = TRUE;
+static level_t default_loglevel = 1;
+
+/* global variables */
+tpm_tss_t *tpm;
+chunk_t digest;
+chunk_t pcr_value;
+
+/**
+ * logging function for tpm_extendpcr
+ */
+static void tpm_extendpcr_dbg(debug_t group, level_t level, char *fmt, ...)
+{
+	char buffer[8192];
+	char *current = buffer, *next;
+	va_list args;
+
+	if (level <= default_loglevel)
+	{
+		if (log_to_stderr)
+		{
+			va_start(args, fmt);
+			vfprintf(stderr, fmt, args);
+			va_end(args);
+			fprintf(stderr, "\n");
+		}
+		if (log_to_syslog)
+		{
+			/* write in memory buffer first */
+			va_start(args, fmt);
+			vsnprintf(buffer, sizeof(buffer), fmt, args);
+			va_end(args);
+
+			/* do a syslog with every line */
+			while (current)
+			{
+				next = strchr(current, '\n');
+				if (next)
+				{
+					*(next++) = '\0';
+				}
+				syslog(LOG_INFO, "%s\n", current);
+				current = next;
+			}
+		}
+	}
+}
+
+/**
+ * Initialize logging to stderr/syslog
+ */
+static void init_log(const char *program)
+{
+	dbg = tpm_extendpcr_dbg;
+
+	if (log_to_stderr)
+	{
+		setbuf(stderr, NULL);
+	}
+	if (log_to_syslog)
+	{
+		openlog(program, LOG_CONS | LOG_NDELAY | LOG_PID, LOG_AUTHPRIV);
+	}
+}
+
+/**
+ * @brief exit tpm_extendpcr
+ *
+ * @param status 0 = OK, -1 = general discomfort
+ */
+static void exit_tpm_extendpcr(err_t message, ...)
+{
+	int status = 0;
+
+	DESTROY_IF(tpm);
+	chunk_free(&digest);
+	chunk_free(&pcr_value);
+
+	/* print any error message to stderr */
+	if (message != NULL && *message != '\0')
+	{
+		va_list args;
+		char m[8192];
+
+		va_start(args, message);
+		vsnprintf(m, sizeof(m), message, args);
+		va_end(args);
+
+		fprintf(stderr, "tpm_extendpcr error: %s\n", m);
+		status = -1;
+	}
+	library_deinit();
+	exit(status);
+}
+
+/**
+ * @brief prints the usage of the program to the stderr output
+ *
+ * If message is set, program is exited with 1 (error)
+ * @param message message in case of an error
+ */
+static void usage(const char *message)
+{
+	fprintf(stderr,
+		"Usage: tpm_extendpcr [--alg <name>] --pcr <nr> --digest <hex>|--in"
+		" <file>\n"
+		"                     [--hash] [--out <file>] [--quiet]"
+		" [--debug <level>]\n"
+		"       tpm_extendpcr  --help\n"
+		"\n"
+		"Options:\n"
+		" --alg (-a)     hash algorithm (sha1|sha256)\n"
+		" --pcr (-p)     platform configuration register (0..23)\n"
+		" --digest (-d)  digest in hex format to be extended\n"
+		" --in (-i)      binary input file with digest to be extended\n"
+		" --hash (-x)    prehash the input file to create digest\n"
+		" --out (-o)     binary output file with updated PCR value\n"
+		" --help (-h)    show usage and exit\n"
+		"\n"
+		"Debugging output:\n"
+		" --debug (-l)   changes the log level (-1..4, default: 1)\n"
+		" --quiet (-q)   do not write log output to stderr\n"
+		);
+	exit_tpm_extendpcr(message);
+}
+
+/**
+ * @brief main of tpm_extendpcr which extends digest into a PCR
+ *
+ * @param argc number of arguments
+ * @param argv pointer to the argument values
+ */
+int main(int argc, char *argv[])
+{
+	hash_algorithm_t alg = HASH_SHA1;
+	hasher_t *hasher = NULL;
+	char *infile = NULL, *outfile = NULL;
+	uint32_t pcr = 16;
+	bool hash = FALSE;
+
+	atexit(library_deinit);
+	if (!library_init(NULL, "tpm_extendpcr"))
+	{
+		exit(SS_RC_LIBSTRONGSWAN_INTEGRITY);
+	}
+	if (lib->integrity &&
+		!lib->integrity->check_file(lib->integrity, "tpm_extendpcr", argv[0]))
+	{
+		fprintf(stderr, "integrity check of tpm_extendpcr failed\n");
+		exit(SS_RC_DAEMON_INTEGRITY);
+	}
+
+	for (;;)
+	{
+		static const struct option long_opts[] = {
+			/* name, has_arg, flag, val */
+			{ "help", no_argument, NULL, 'h' },
+			{ "alg", required_argument, NULL, 'a' },
+			{ "pcr", required_argument, NULL, 'p' },
+			{ "digest", required_argument, NULL, 'd' },
+			{ "in", required_argument, NULL, 'i' },
+			{ "hash", no_argument, NULL, 'x' },
+			{ "out", required_argument, NULL, 'o' },
+			{ "quiet", no_argument, NULL, 'q' },
+			{ "debug", required_argument, NULL, 'l' },
+			{ 0,0,0,0 }
+		};
+
+		/* parse next option */
+		int c = getopt_long(argc, argv, "ha:p:d:i:xo:ql:", long_opts, NULL);
+
+		switch (c)
+		{
+			case EOF:       /* end of flags */
+				break;
+
+			case 'h':       /* --help */
+				usage(NULL);
+
+			case 'a':       /* --alg <name> */
+				if (!enum_from_name(hash_algorithm_short_names, optarg, &alg))
+				{
+					usage("unsupported hash algorithm");
+				}
+				continue;
+			case 'p':       /* --pcr <nr> */
+				pcr = atoi(optarg);
+				continue;
+
+			case 'd':       /* --digest <hex> */
+				digest = chunk_from_hex(chunk_from_str(optarg), NULL);
+				continue;
+
+			case 'i':       /* --in <file> */
+				infile = optarg;
+				continue;
+
+			case 'x':       /* --hash */
+				hash = TRUE;
+				continue;
+
+			case 'o':       /* --out <file> */
+				outfile = optarg;
+				continue;
+
+			case 'q':       /* --quiet */
+				log_to_stderr = FALSE;
+				continue;
+
+			case 'l':		/* --debug <level> */
+				default_loglevel = atoi(optarg);
+				continue;
+
+			default:
+				usage("unknown option");
+		}
+		/* break from loop */
+		break;
+	}
+
+	init_log("tpm_extendpcr");
+
+	if (!lib->plugins->load(lib->plugins,
+			lib->settings->get_str(lib->settings, "tpm_extendpcr.load",
+												  "tpm sha1 sha2")))
+	{
+		exit_tpm_extendpcr("plugin loading failed");
+	}
+
+	/* try to find a TPM */
+	tpm = tpm_tss_probe(TPM_VERSION_ANY);
+	if (!tpm)
+	{
+		exit_tpm_extendpcr("no TPM found");
+	}
+
+	/* read digest from file */
+	if (digest.len == 0)
+	{
+		chunk_t *chunk;
+
+		if (!infile)
+		{
+			exit_tpm_extendpcr("--digest or --in option required");
+		}
+		chunk = chunk_map(infile, FALSE);
+		if (!chunk)
+		{
+			exit_tpm_extendpcr("reading input file failed");
+		}
+		if (hash)
+		{
+			hasher = lib->crypto->create_hasher(lib->crypto, alg);
+			if (!hasher || !hasher->allocate_hash(hasher, *chunk, &digest))
+			{
+				DESTROY_IF(hasher);
+				chunk_unmap(chunk);
+				exit_tpm_extendpcr("prehashing infile failed");
+			}
+			hasher->destroy(hasher);
+		}
+		else
+		{
+			digest = chunk_clone(*chunk);
+		}
+		chunk_unmap(chunk);
+	}
+	DBG1(DBG_PTS, "Digest: %#B", &digest);
+
+	/* extend digest into PCR */
+	if (!tpm->extend_pcr(tpm, pcr, &pcr_value, digest, alg))
+	{
+		exit_tpm_extendpcr("extending PCR failed");
+	}
+	DBG1(DBG_PTS, "PCR %02u: %#B", pcr, &pcr_value);
+
+	/* write PCR value to file */
+	if (outfile)
+	{
+		if (!chunk_write(pcr_value, outfile, 022, TRUE))
+		{
+			DBG1(DBG_PTS, "writing '%s' failed", outfile);
+		}
+	}
+	chunk_free(&pcr_value);
+
+	exit_tpm_extendpcr(NULL);
+	return -1; /* should never be reached */
+}