IABSD.fr/src/usr.sbin/installboot/bootstrap.c

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• Author : deraadt
  Date : 2019-06-28 13:32:41
  Hash : df69c215
  Message : When system calls indicate an error they return -1, not some arbitrary value < 0. errno is only updated in this case. Change all (most?) callers of syscalls to follow this better, and let's see if this strictness helps us in the future.

• usr.sbin/installboot/bootstrap.c

• /*	$OpenBSD: bootstrap.c,v 1.13 2019/06/28 13:32:48 deraadt Exp $	*/
  
  /*
   * Copyright (c) 2013 Joel Sing <jsing@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <sys/param.h>	/* DEV_BSIZE */
  #include <sys/disklabel.h>
  #include <sys/dkio.h>
  #include <sys/ioctl.h>
  #include <sys/stat.h>
  
  #include <err.h>
  #include <fcntl.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include "installboot.h"
  
  void
  bootstrap(int devfd, char *dev, char *bootfile)
  {
  	struct disklabel dl;
  	struct disklabel *lp;
  	struct partition *pp;
  	char *boot, *p, part;
  	size_t bootsize;
  	size_t bootsec;
  	struct stat sb;
  	int fd, i;
  
  	/*
  	 * Install bootstrap code onto the given disk, preserving the
  	 * existing disklabel.
  	 */
  
  	/* Read disklabel from disk. */
  	if (ioctl(devfd, DIOCGDINFO, &dl) == -1)
  		err(1, "disklabel");
  	if (dl.d_secsize == 0) {
  		warnx("disklabel has sector size of 0, assuming %d", DEV_BSIZE);
  		dl.d_secsize = DEV_BSIZE;
  	}
  
  	/* Read bootstrap file. */
  	if (verbose)
  		fprintf(stderr, "reading bootstrap from %s\n", bootfile);
  	fd = open(bootfile, O_RDONLY);
  	if (fd == -1)
  		err(1, "open %s", bootfile);
  	if (fstat(fd, &sb) == -1)
  		err(1, "fstat %s", bootfile);
  	bootsec = howmany((ssize_t)sb.st_size, dl.d_secsize);
  	bootsize = bootsec * dl.d_secsize;
  	if (verbose)
  		fprintf(stderr, "bootstrap is %zu bytes "
  		    "(%zu sectors @ %u bytes = %zu bytes)\n",
  		    (ssize_t)sb.st_size, bootsec, dl.d_secsize, bootsize);
  	boot = calloc(1, bootsize);
  	if (boot == NULL)
  		err(1, "calloc");
  	if (read(fd, boot, bootsize) != (ssize_t)sb.st_size)
  		err(1, "read");
  	close(fd);
  
  	/*
  	 * Check that the bootstrap will fit - partitions must not overlap,
  	 * or if they do, the partition type must be either FS_BOOT or
  	 * FS_UNUSED. The 'c' partition will always overlap and is ignored.
  	 */
  	if (verbose)
  		fprintf(stderr, "ensuring used partitions do not overlap "
  		    "with bootstrap sectors 0-%zu\n", bootsec);
  	for (i = 0; i < dl.d_npartitions; i++) {
  		part = 'a' + i;
  		pp = &dl.d_partitions[i];
  		if (i == RAW_PART)
  			continue;
  		if (DL_GETPSIZE(pp) == 0)
  			continue;
  		if ((u_int64_t)bootsec <= DL_GETPOFFSET(pp))
  			continue;
  		switch (pp->p_fstype) {
  		case FS_BOOT:
  			break;
  		case FS_UNUSED:
  			warnx("bootstrap overlaps with unused partition %c",
  			    part);
  			break;
  		default:
  			errx(1, "bootstrap overlaps with partition %c", part);
  		}
  	}
  
  	/*
  	 * Make sure the bootstrap has left space for the disklabel.
  	 * N.B.: LABELSECTOR *is* a DEV_BSIZE quantity!
  	 */
  	lp = (struct disklabel *)(boot + (LABELSECTOR * DEV_BSIZE) +
  	    LABELOFFSET);
  	for (i = 0, p = (char *)lp; i < (int)sizeof(*lp); i++)
  		if (p[i] != 0)
  			errx(1, "bootstrap has data in disklabel area");
  
  	/* Patch the disklabel into the bootstrap code. */
  	memcpy(lp, &dl, sizeof(dl));
  
  	/* Write the bootstrap out to the disk. */
  	if (verbose)
  		fprintf(stderr, "%s bootstrap to disk\n",
  		    (nowrite ? "would write" : "writing"));
  	if (nowrite)
  		return;
  	if (pwrite(devfd, boot, bootsize, 0) != (ssize_t)bootsize)
  		err(1, "pwrite");
  }