8fc0d7a9c3
This closes a hole pointed out by Thor Lancelot Simon on tech-kern ~3 years ago. The problem was with running binaries from remote storage, where our kernel (and Veriexec) has no control over any changes to files. An attacker could, after the fingerprint has been verified and program loaded to memory, inject malicious code into the backing store on the remote storage, followed by a forced flush, causing a page-in of the malicious data from backing store, bypassing integrity checks. Initial implementation by Brett Lymn.
245 lines
5.4 KiB
C
245 lines
5.4 KiB
C
/* $NetBSD: veriexecctl.c,v 1.17 2005/10/05 13:48:48 elad Exp $ */
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/*-
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* Copyright 2005 Elad Efrat <elad@bsd.org.il>
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* Copyright 2005 Brett Lymn <blymn@netbsd.org>
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*
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* All rights reserved.
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*
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* This code has been donated to The NetBSD Foundation by the Author.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. The name of the author may not be used to endorse or promote products
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* derived from this software withough specific prior written permission
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*
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*/
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#include <sys/ioctl.h>
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#include <sys/param.h>
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#include <sys/queue.h>
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#include <sys/verified_exec.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <err.h>
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#include <errno.h>
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#include "veriexecctl.h"
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#define VERIEXEC_DEVICE "/dev/veriexec"
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extern struct veriexec_params params; /* in veriexecctl_parse.y */
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extern char *filename; /* in veriexecctl_conf.l */
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extern int yynerrs;
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int gfd, verbose = 0, phase;
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size_t line;
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/*
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* Prototypes
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*/
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static FILE *openlock(const char *);
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static void phase1_preload(void);
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static int fingerprint_load(char*);
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static void usage(void) __attribute__((__noreturn__));
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static FILE *
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openlock(const char *path)
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{
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int lfd;
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if ((lfd = open(path, O_RDONLY|O_EXLOCK, 0)) == -1)
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return NULL;
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return fdopen(lfd, "r");
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}
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struct veriexec_up *
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dev_lookup(dev_t d)
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{
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struct veriexec_up *p;
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CIRCLEQ_FOREACH(p, ¶ms_list, vu_list)
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if (p->vu_param.dev == d)
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return (p);
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return NULL;
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}
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struct veriexec_up *
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dev_add(dev_t d)
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{
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struct veriexec_up *up;
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if ((up = calloc((size_t)1, sizeof(*up))) == NULL)
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err(1, "No memory");
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up->vu_param.dev = d;
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up->vu_param.hash_size = 1;
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CIRCLEQ_INSERT_TAIL(¶ms_list, up, vu_list);
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return up;
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}
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/* Load all devices, get rid of the list. */
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static void
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phase1_preload(void)
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{
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if (verbose)
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printf("Phase 1: Calculating hash table sizes:\n");
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while (!CIRCLEQ_EMPTY(¶ms_list)) {
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struct veriexec_up *vup;
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vup = CIRCLEQ_FIRST(¶ms_list);
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if (ioctl(gfd, VERIEXEC_TABLESIZE, &(vup->vu_param)) == -1) {
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if (errno != EEXIST)
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err(1, "Error in phase 1: Can't "
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"set hash table size for device %d",
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vup->vu_param.dev);
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}
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if (verbose) {
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printf(" => Hash table sizing successful for device "
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"%d. (%zu entries)\n", vup->vu_param.dev,
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vup->vu_param.hash_size);
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}
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CIRCLEQ_REMOVE(¶ms_list, vup, vu_list);
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free(vup);
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}
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}
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/*
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* Load the fingerprint. Assumes that the fingerprint pseudo-device is
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* opened and the file handle is in gfd.
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*/
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void
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phase2_load(void)
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{
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/*
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* If there's no access type specified, use the default.
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*/
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if (!(params.type & (VERIEXEC_DIRECT|VERIEXEC_INDIRECT|VERIEXEC_FILE)))
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params.type |= VERIEXEC_DIRECT;
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if (ioctl(gfd, VERIEXEC_LOAD, ¶ms) == -1)
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warn("Cannot load params from `%s'", params.file);
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free(params.fingerprint);
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}
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/*
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* Fingerprint load handling.
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*/
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static int
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fingerprint_load(char *ifile)
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{
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CIRCLEQ_INIT(¶ms_list);
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memset(¶ms, 0, sizeof(params));
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if ((yyin = openlock(ifile)) == NULL)
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err(1, "Cannot open `%s'", ifile);
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/*
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* Phase 1: Scan all config files, creating the list of devices
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* we have fingerprinted files on, and the amount of
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* files per device. Lock all files to maintain sync.
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*/
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phase = 1;
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if (verbose) {
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(void)printf("Phase 1: Building hash table information:\n");
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(void)printf("=> Parsing \"%s\"\n", ifile);
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}
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line = 1;
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yyparse();
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if (yynerrs)
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return -1;
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phase1_preload();
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/*
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* Phase 2: After we have a circular queue containing all the
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* devices we care about and the sizes for the hash
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* tables, do a rescan, this time actually loading the
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* file data.
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*/
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rewind(yyin);
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phase = 2;
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if (verbose) {
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(void)printf("Phase 2: Loading per-file fingerprints.\n");
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(void)printf("=> Parsing \"%s\"\n", ifile);
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}
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line = 1;
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yyparse();
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(void)fclose(yyin);
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return 0;
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}
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static void
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usage(void)
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{
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(void)fprintf(stderr, "Usage: %s [-v] [load <signature_file>]\n",
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getprogname());
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exit(1);
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}
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int
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main(int argc, char **argv)
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{
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int c;
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setprogname(argv[0]);
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while ((c = getopt(argc, argv, "v")) != -1)
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switch (c) {
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case 'v':
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verbose = 1;
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break;
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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if ((gfd = open(VERIEXEC_DEVICE, O_RDWR, 0)) == -1)
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err(1, "Cannot open `%s'", VERIEXEC_DEVICE);
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/*
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* Handle the different commands we can do.
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*/
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if (argc == 2 && strcasecmp(argv[0], "load") == 0) {
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filename = argv[1];
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fingerprint_load(argv[1]);
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} else
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usage();
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(void)close(gfd);
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return 0;
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}
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