Adding upstream version 2:2.1.0.upstream/2%2.1.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 371 insertions, 0 deletions

diff --git a/misc/keyslot_checker/chk_luks_keyslots.c b/misc/keyslot_checker/chk_luks_keyslots.c
new file mode 100644
index 0000000..d05aad8
--- /dev/null
+++ b/misc/keyslot_checker/chk_luks_keyslots.c
@@ -0,0 +1,371 @@
+/*
+ * LUKS keyslot entropy tester. Works only for header version 1.
+ *
+ * Functionality: Determines sample entropy (symbols: bytes) for
+ * each (by default) 512B sector in each used keyslot. If it
+ * is lower than a threshold, the sector address is printed
+ * as it is suspected of having non-"random" data in it, indicating
+ * damage by overwriting. This can obviously not find overwriting
+ * with random or random-like data (encrypted, compressed).
+ *
+ * Version history:
+ *    v0.1: 09.09.2012 Initial release
+ *    v0.2: 08.10.2012 Converted to use libcryptsetup
+ *
+ * Copyright (C) 2012, Arno Wagner <arno@wagner.name>
+ *
+ * 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.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <math.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <libcryptsetup.h>
+
+const char *help =
+"Version 0.2 [8.10.2012]\n"
+"\n"
+"    chk_luks_keyslots [options] luks-device \n"
+"\n"
+"This tool checks all keyslots of a LUKS device for \n"
+"low entropy sections. If any are found, they are reported. \n"
+"This allows to find areas damaged by things like filesystem \n"
+"creation or RAID superblocks. \n"
+"\n"
+"Options: \n"
+"  -t <num>  Entropy threshold. Possible values 0.0 ... 1.0 \n"
+"            Default: 0.90, which works well for 512B sectors.\n"
+"            For 512B sectors, you will get frequent misdetections\n"
+"            at thresholds around 0.94\n"
+"            Higher value: more sensitive but more false detections.\n"
+"  -s <num>  Sector size. Must divide keyslot-size.\n"
+"            Default: 512 Bytes.\n"
+"            Values smaller than 128 are generally not very useful.\n"
+"            For values smaller than the default, you need to adjust\n"
+"            the threshold down to reduce misdetection. For values\n"
+"            larger than the default you need to adjust the threshold\n"
+"            up to retain sensitivity.\n"
+"  -v        Print found suspicious sectors verbosely. \n"
+"  -d        Print decimal addresses instead of hex ones.\n"
+"\n";
+
+
+/* Config defaults */
+
+static int sector_size = 512;
+static double threshold = 0.90;
+static int print_decimal = 0;
+static int verbose = 0;
+
+/* tools */
+
+/* Calculates and returns sample entropy on byte level for
+ * The argument.
+ */
+static double ent_samp(unsigned char * buf, int len)
+{
+	int freq[256];   /* stores symbol frequencies */
+	int i;
+	double e, f;
+
+	/* 0. Plausibility checks */
+	if (len <= 0)
+		return 0.0;
+
+	/* 1. count all frequencies */
+	for (i = 0; i < 256; i++) {
+		freq[i] = 0.0;
+	}
+
+	for (i = 0; i < len; i ++)
+		freq[buf[i]]++;
+
+	/* 2. calculate sample entropy */
+	e = 0.0;
+	for (i = 0; i < 256; i++) {
+		f = freq[i];
+		if (f > 0) {
+			f =  f / (double)len;
+			e += f * log2(f);
+		}
+	}
+
+	if (e != 0.0)
+		e = -1.0 * e;
+
+	e = e / 8.0;
+	return e;
+}
+
+static void print_address(FILE *out, uint64_t value)
+{
+	if (print_decimal) {
+		fprintf(out,"%08" PRIu64 " ", value);
+	} else {
+		fprintf(out,"%#08" PRIx64 " ", value);
+	}
+}
+
+/* uses default "hd" style, i.e. 16 bytes followed by ASCII */
+static void hexdump_line(FILE *out, uint64_t address, unsigned char *buf) {
+	int i;
+	static char tbl[16] = "0123456789ABCDEF";
+
+	fprintf(out,"  ");
+	print_address(out, address);
+	fprintf(out," ");
+
+	/* hex */
+	for (i = 0; i < 16; i++) {
+		fprintf(out, "%c%c",
+			tbl[(unsigned char)buf[i]>> 4],
+			tbl[(unsigned char)buf[i] & 0x0f]);
+		fprintf(out," ");
+		if (i == 7)
+			fprintf(out," ");
+	}
+
+	fprintf(out," ");
+
+	/* ascii */
+	for (i = 0; i < 16; i++) {
+		if (isprint(buf[i])) {
+			fprintf(out, "%c", buf[i]);
+		} else {
+			fprintf(out, ".");
+		}
+	}
+	fprintf(out, "\n");
+}
+
+static void hexdump_sector(FILE *out, unsigned char *buf, uint64_t address, int len)
+{
+	int done;
+
+	done = 0;
+	while (len - done >= 16) {
+		hexdump_line(out, address + done, buf + done);
+		done += 16;
+	}
+}
+
+static int check_keyslots(FILE *out, struct crypt_device *cd, int f_luks)
+{
+	int i;
+	double ent;
+	off_t ofs;
+	uint64_t start, length, end;
+	crypt_keyslot_info ki;
+	unsigned char buffer[sector_size];
+
+	for (i = 0; i < crypt_keyslot_max(CRYPT_LUKS1) ; i++) {
+		fprintf(out, "- processing keyslot %d:", i);
+		ki = crypt_keyslot_status(cd, i);
+		if (ki == CRYPT_SLOT_INACTIVE) {
+			fprintf(out, "  keyslot not in use\n");
+			continue;
+		}
+
+		if (ki == CRYPT_SLOT_INVALID) {
+			fprintf(out, "\nError: keyslot invalid.\n");
+			return EXIT_FAILURE;
+		}
+
+		if (crypt_keyslot_area(cd, i, &start, &length) < 0) {
+			fprintf(stderr,"\nError: querying keyslot area failed for slot %d\n", i);
+			perror(NULL);
+			return EXIT_FAILURE;
+		}
+		end = start + length;
+
+		fprintf(out, "  start: ");
+		print_address(out, start);
+		fprintf(out, "  end: ");
+		print_address(out, end);
+		fprintf(out, "\n");
+
+		/* check whether sector-size divides size */
+		if (length % sector_size != 0) {
+			fprintf(stderr,"\nError: Argument to -s does not divide keyslot size\n");
+			return EXIT_FAILURE;
+		}
+
+		for (ofs = start; (uint64_t)ofs < end; ofs += sector_size) {
+			if (lseek(f_luks, ofs, SEEK_SET) != ofs) {
+				fprintf(stderr,"\nCannot seek to keyslot area.\n");
+				return EXIT_FAILURE;
+			}
+			if (read(f_luks, buffer, sector_size) != sector_size) {
+				fprintf(stderr,"\nCannot read keyslot area.\n");
+				return EXIT_FAILURE;
+			}
+			ent = ent_samp(buffer, sector_size);
+			if (ent < threshold) {
+				fprintf(out, "  low entropy at: ");
+				print_address(out, ofs);
+				fprintf(out, "   entropy: %f\n", ent);
+				if (verbose) {
+					fprintf(out, "  Binary dump:\n");
+					hexdump_sector(out, buffer, (uint64_t)ofs, sector_size);
+					fprintf(out,"\n");
+				}
+			}
+		}
+	}
+
+	return EXIT_SUCCESS;
+}
+
+/* Main */
+int main(int argc, char **argv)
+{
+	/* for option processing */
+	int c, r;
+	char *device;
+
+	/* for use of libcryptsetup */
+	struct crypt_device *cd;
+
+	/* Other vars */
+	int f_luks;   /* device file for the luks device */
+	FILE *out;
+
+	/* temporary helper vars */
+	int res;
+
+	/* getopt values */
+	char *s, *end;
+	double tvalue;
+	int svalue;
+
+	/* global initializations */
+	out = stdout;
+
+	/* get commandline parameters */
+	while ((c = getopt (argc, argv, "t:s:vd")) != -1) {
+		switch (c) {
+		case 't':
+			s = optarg;
+			tvalue = strtod(s, &end);
+			if (s == end) {
+				fprintf(stderr, "\nError: Parsing of argument to -t failed.\n");
+				exit(EXIT_FAILURE);
+			}
+
+			if (tvalue < 0.0 || tvalue > 1.0) {
+				fprintf(stderr,"\nError: Argument to -t must be in 0.0 ... 1.0\n");
+				exit(EXIT_FAILURE);
+			}
+			threshold = tvalue;
+			break;
+		case 's':
+			s = optarg;
+			svalue = strtol(s, &end, 10);
+			if (s == end) {
+				fprintf(stderr, "\nError: Parsing of argument to -s failed.\n");
+				exit(EXIT_FAILURE);
+			}
+
+			if (svalue < 1) {
+				fprintf(stderr,"\nError: Argument to -s must be >= 1 \n");
+				exit(EXIT_FAILURE);
+			}
+			sector_size = svalue;
+			break;
+		case 'v':
+			verbose = 1;
+			break;
+		case 'd':
+			print_decimal = 1;
+			break;
+		case '?':
+			if (optopt == 't' || optopt == 's')
+				fprintf (stderr,"\nError: Option -%c requires an argument.\n",
+					 optopt);
+			else if (isprint (optopt)) {
+				fprintf(stderr,"\nError: Unknown option `-%c'.\n", optopt);
+				fprintf(stderr,"\n\n%s", help);
+			} else {
+				fprintf (stderr, "\nError: Unknown option character `\\x%x'.\n",
+					 optopt);
+				fprintf(stderr,"\n\n%s", help);
+			}
+			exit(EXIT_SUCCESS);
+		default:
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	/* parse non-option stuff. Should be exactly one, the device. */
+	if (optind+1 != argc) {
+		fprintf(stderr,"\nError: exactly one non-option argument expected!\n");
+		fprintf(stderr,"\n\n%s", help);
+		exit(EXIT_FAILURE);
+	}
+	device = argv[optind];
+
+	/* test whether we can open and read device */
+	/* This is needed as we are reading the actual data
+	* in the keyslots directly from the LUKS container.
+	*/
+	f_luks = open(device, O_RDONLY);
+	if (f_luks == -1) {
+		fprintf(stderr,"\nError: Opening of device %s failed:\n", device);
+		perror(NULL);
+		exit(EXIT_FAILURE);
+	}
+
+	/* now get the parameters we need via libcryptsetup */
+	/* Basically we need all active keyslots and their placement on disk */
+
+	/* first init. This does the following:
+	 *   - gets us a crypt_device struct with some values filled in
+	 *     Note: This does some init stuff we do not need, but that
+	 *     should not cause trouble.
+	 */
+
+	res = crypt_init(&cd, device);
+	if (res < 0) {
+		fprintf(stderr, "crypt_init() failed. Maybe not running as root?\n");
+		close(f_luks);
+		exit(EXIT_FAILURE);
+	}
+
+	/* now load LUKS header into the crypt_device
+	 * This should also make sure a valid LUKS1 header is on disk
+	 * and hence we should be able to skip magic and version checks.
+	 */
+	res = crypt_load(cd, CRYPT_LUKS1, NULL);
+	if (res < 0) {
+		fprintf(stderr, "crypt_load() failed. LUKS header too broken/absent?\n");
+		crypt_free(cd);
+		close(f_luks);
+		exit(EXIT_FAILURE);
+	}
+
+	fprintf(out, "\nparameters (commandline and LUKS header):\n");
+	fprintf(out, "  sector size: %d\n", sector_size);
+	fprintf(out, "  threshold:   %0f\n\n", threshold);
+
+	r = check_keyslots(out, cd, f_luks);
+
+	crypt_free(cd);
+	close(f_luks);
+	return r;
+}