usr.sbin/asf/asf_kvm.c

   1 /*-
   2  * Copyright (c) 2006 The FreeBSD Project
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  29
  30 #include <sys/types.h>
  31 #include <sys/param.h>
  32 #include <sys/queue.h>  /* for <sys/linker.h> with _KERNEL defined */
  33 #include <err.h>
  34 #include <fcntl.h>
  35 #include <kvm.h>
  36 #include <limits.h>
  37 #include <nlist.h>
  38 #include <stdlib.h>
  39 #include <string.h>
  40
  41 #define _KERNEL
  42 #include <sys/linker.h>
  43 #undef  _KERNEL
  44
  45 #include "asf.h"
  46
  47 /* Name of the head of the linker file list in /sys/kern/kern_linker.c */
  48 #define LINKER_HEAD     "linker_files"
  49
  50 /*
  51  * Get the list of linker files using kvm(3).
  52  * Can work with a live kernel as well as with a crash dump.
  53  */
  54 void
  55 asf_kvm(const char *kernfile, const char *corefile)
  56 {
  57         char errbuf[LINE_MAX];
  58         char name[PATH_MAX];
  59         kvm_t *kd;
  60         struct nlist nl[2];
  61         struct linker_file lf;
  62         linker_file_list_t linker_files;
  63         ssize_t n;
  64         void *kp;
  65
  66         kd = kvm_openfiles(kernfile, corefile, NULL, O_RDONLY, errbuf);
  67         if (kd == NULL)
  68                 errx(2, "open kernel memory: %s", errbuf);
  69
  70         /*
  71          * Locate the head of the linker file list using kernel symbols.
  72          */
  73         strcpy(name, LINKER_HEAD);
  74         nl[0].n_name = name; /* can't use LINKER_HEAD here because it's const */
  75         nl[1].n_name = NULL; /* terminate the array for kvm_nlist() */
  76         switch (kvm_nlist(kd, nl)) {
  77         case 0:
  78                 break;
  79         case -1:
  80                 warnx("%s: %s", LINKER_HEAD, kvm_geterr(kd));
  81                 kvm_close(kd);
  82                 exit(2);
  83         default:
  84                 kvm_close(kd);
  85                 errx(2, "%s: symbol not found", LINKER_HEAD);
  86         }
  87
  88         /*
  89          * Read the head of the linker file list from kernel memory.
  90          */
  91         n = kvm_read(kd, nl[0].n_value, &linker_files, sizeof(linker_files));
  92         if (n == -1)
  93                 goto read_err;
  94         if (n != sizeof(linker_files)) {
  95                 kvm_close(kd);
  96                 errx(2, "%s: short read", LINKER_HEAD);
  97         }
  98
  99         /*
 100          * Traverse the linker file list starting at its head.
 101          */
 102         for (kp = linker_files.tqh_first; kp; kp = lf.link.tqe_next) {
 103                 /* Read a linker file structure */
 104                 n = kvm_read(kd, (u_long)kp, &lf, sizeof(lf));
 105                 if (n == -1)
 106                         goto read_err;
 107                 if (n != sizeof(lf)) {
 108                         kvm_close(kd);
 109                         errx(2, "kvm: short read");
 110                 }
 111                 /* Read the name of the file stored separately */
 112                 bzero(name, sizeof(name));
 113                 n = kvm_read(kd, (u_long)lf.filename, name, sizeof(name) - 1);
 114                 if (n == -1)
 115                         goto read_err;
 116                 if (strcmp(name, KERNFILE) == 0)
 117                         continue;
 118                 /* Add this file to our list of linker files */
 119                 kfile_add(name, lf.address);
 120         }
 121         kvm_close(kd);
 122         return;
 123
 124 read_err:       /* A common error case */
 125         warnx("read kernel memory: %s", kvm_geterr(kd));
 126         kvm_close(kd);
 127         exit(2);
 128 }