rmmod.c

   1 /* rmmod.c: remove a module from the kernel.
   2     Copyright (C) 2001  Rusty Russell.
   3     Copyright (C) 2002  Rusty Russell, IBM Corporation.
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 */
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <errno.h>
  24 #include <fcntl.h>
  25 #include <asm/unistd.h>
  26 #include <stdarg.h>
  27 #include <getopt.h>
  28 #include <syslog.h>
  29
  30 #include "util.h"
  31 #include "logging.h"
  32 #include "testing.h"
  33
  34 extern long delete_module(const char *, unsigned int);
  35
  36 static char *next_field(const char *line)
  37 {
  38         const char *rest;
  39
  40         rest = line + strcspn(line, " ");
  41         rest += strspn(rest, " ");
  42         return (char *)rest;
  43 }
  44
  45 /* Report that the module is in use. */
  46 static void mod_in_use(const char *modname, char *usedby)
  47 {
  48         /* New /proc/modules uses a single "-" to mean "nothing".  Old
  49            one just puts nothing there. */
  50         if (usedby[0] == '-' || streq(usedby, "")) {
  51                 error("Module %s is in use\n", modname);
  52                 return;
  53         }
  54
  55         /* New /proc/modules *always* prints commas (even if only one) */
  56         if (strchr(usedby, ','))
  57                 /* Blatt over trailing comma for neatness */
  58                 usedby[strcspn(usedby, " \n")-1] = '\0';
  59         else {
  60                 /* Older /proc/modules just put them as
  61                    space-separated names.  Blatt over trailing \n */
  62                 usedby[strlen(usedby)-1] = '\0';
  63         }
  64
  65         error("Module %s is in use by %s\n", modname, usedby);
  66 }
  67
  68 /* If we can check usage without entering kernel, do so. */
  69 static int check_usage(const char *modname)
  70 {
  71         FILE *module_list;
  72         char line[10240], name[64];
  73         unsigned long size, refs;
  74         int scanned;
  75
  76         module_list = fopen("/proc/modules", "r");
  77         if (!module_list) {
  78                 if (errno == ENOENT) /* /proc may not be mounted. */
  79                         return 0;
  80                 fatal("can't open /proc/modules: %s\n", strerror(errno));
  81         }
  82         while (fgets(line, sizeof(line)-1, module_list) != NULL) {
  83                 if (strchr(line, '\n') == NULL) {
  84                         fatal("V. v. long line broke rmmod.\n");
  85                         exit(1);
  86                 }
  87
  88                 scanned = sscanf(line, "%s %lu %lu", name, &size, &refs);
  89                 if (strcmp(name, modname) != 0)
  90                         continue;
  91
  92                 if (scanned < 2)
  93                         fatal("Unknown format in /proc/modules: %s\n", line);
  94
  95                 if (scanned == 2)
  96                         fatal("Kernel does not have unload support.\n");
  97
  98                 /* Hand it fields 3 onwards. */
  99                 if (refs != 0)
 100                         mod_in_use(modname,
 101                                    next_field(next_field(next_field(line))));
 102                 goto out;
 103         }
 104         error("Module %s does not exist in /proc/modules\n", modname);
 105         refs = 1;
 106  out:
 107         fclose(module_list);
 108         return (refs == 0) ? 0 : -EINVAL;
 109 }
 110
 111 static int rmmod(const char *path, int flags)
 112 {
 113         long ret;
 114         char name[strlen(path) + 1];
 115
 116         filename2modname(name, path);
 117
 118         if ((flags & O_NONBLOCK) && !(flags & O_TRUNC)) {
 119                 if (check_usage(name) != 0)
 120                         return 1;
 121         }
 122
 123         info("rmmod %s, wait=%s%s\n", name,
 124              (flags & O_NONBLOCK) ? "no" : "yes",
 125              (flags & O_TRUNC) ? " force" : "");
 126
 127         ret = delete_module(name, flags);
 128         if (ret != 0)
 129                 error("Removing '%s': %s\n", name, strerror(errno));
 130         return ret;
 131 }
 132
 133 static const struct option options[] = { { "all", 0, NULL, 'a' },
 134                                    { "force", 0, NULL, 'f' },
 135                                    { "help", 0, NULL, 'h' },
 136                                    { "syslog", 0, NULL, 's' },
 137                                    { "verbose", 0, NULL, 'v' },
 138                                    { "version", 0, NULL, 'V' },
 139                                    { "wait", 0, NULL, 'w' },
 140                                    { NULL, 0, NULL, 0 } };
 141
 142 static void print_usage(const char *progname)
 143 {
 144         fprintf(stderr,
 145                 "Usage: %s [-fhswvV] modulename ...\n"
 146                 // " -a (or --all) to remove all modules (no names needed)\n"
 147                 " -f (or --force) forces a module unload, and may crash your\n"
 148                 "    machine.  This requires the Forced Module Removal option\n"
 149                 "    when the kernel was compiled.\n"
 150                 " -h (or --help) prints this help text\n"
 151                 " -s (or --syslog) says use syslog, not stderr\n"
 152                 " -v (or --verbose) enables more messages\n"
 153                 " -V (or --version) prints the version code\n"
 154                 " -w (or --wait) begins a module removal even if it is used\n"
 155                 "    and will stop new users from accessing the module (so it\n"
 156                 "    should eventually fall to zero).\n"
 157                 , progname);
 158         exit(1);
 159 }
 160
 161 int main(int argc, char *argv[])
 162 {
 163         /* O_EXCL so kernels can spot old rmmod versions */
 164         unsigned int flags = O_NONBLOCK|O_EXCL;
 165         int i, opt, all = 0;
 166         int ret, err;
 167
 168         while ((opt = getopt_long(argc, argv,
 169                         "afh?swvV", options, NULL)) != EOF) {
 170                 switch (opt) {
 171                 case 'a':       // --all
 172                         all = 1;
 173                         break;
 174                 case 'f':       // --force
 175                         flags |= O_TRUNC;
 176                         break;
 177                 case 's':       // --syslog
 178                         openlog("rmmod", LOG_CONS, LOG_DAEMON);
 179                         logging = 1;
 180                         break;
 181                 case 'w':       // --wait
 182                         flags &= ~O_NONBLOCK;
 183                         break;
 184                 case 'v':       // --verbose
 185                         verbose++;
 186                         break;
 187                 case 'V':       // --version
 188                         puts(PACKAGE " version " VERSION);
 189                         return 0;
 190
 191                 default:
 192                         print_usage(argv[0]);
 193                 }
 194         }
 195         if (!argv[optind]) {
 196                 fprintf(stderr, "no module names given\n");
 197                 print_usage(argv[0]);
 198         }
 199
 200         err = 0;
 201         /* remove each specified module */
 202         for (i = optind; i < argc; i++) {
 203                 ret = rmmod(argv[i], flags);
 204                 if (ret != 0)
 205                         err = 1;
 206         }
 207
 208         if (logging)
 209                 closelog();
 210         exit(err);
 211 }