src/condition.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <stdlib.h>
  23 #include <errno.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #ifdef HAVE_SELINUX
  28 #include <selinux/selinux.h>
  29 #endif
  30
  31 #include "util.h"
  32 #include "condition.h"
  33
  34 Condition* condition_new(ConditionType type, const char *parameter, bool trigger, bool negate) {
  35         Condition *c;
  36
  37         assert(type < _CONDITION_TYPE_MAX);
  38
  39         c = new0(Condition, 1);
  40         if (!c)
  41                 return NULL;
  42
  43         c->type = type;
  44         c->trigger = trigger;
  45         c->negate = negate;
  46
  47         if (parameter) {
  48                 c->parameter = strdup(parameter);
  49                 if (!c->parameter) {
  50                         free(c);
  51                         return NULL;
  52                 }
  53         }
  54
  55         return c;
  56 }
  57
  58 void condition_free(Condition *c) {
  59         assert(c);
  60
  61         free(c->parameter);
  62         free(c);
  63 }
  64
  65 void condition_free_list(Condition *first) {
  66         Condition *c, *n;
  67
  68         LIST_FOREACH_SAFE(conditions, c, n, first)
  69                 condition_free(c);
  70 }
  71
  72 static bool test_kernel_command_line(const char *parameter) {
  73         char *line, *w, *state, *word = NULL;
  74         bool equal;
  75         int r;
  76         size_t l, pl;
  77         bool found = false;
  78
  79         assert(parameter);
  80
  81         if (detect_container(NULL) > 0)
  82                 return false;
  83
  84         r = read_one_line_file("/proc/cmdline", &line);
  85         if (r < 0) {
  86                 log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
  87                 return false;
  88         }
  89
  90         equal = !!strchr(parameter, '=');
  91         pl = strlen(parameter);
  92
  93         FOREACH_WORD_QUOTED(w, l, line, state) {
  94
  95                 free(word);
  96                 word = strndup(w, l);
  97                 if (!word)
  98                         break;
  99
 100                 if (equal) {
 101                         if (streq(word, parameter)) {
 102                                 found = true;
 103                                 break;
 104                         }
 105                 } else {
 106                         if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
 107                                 found = true;
 108                                 break;
 109                         }
 110                 }
 111
 112         }
 113
 114         free(word);
 115         free(line);
 116
 117         return found;
 118 }
 119
 120 static bool test_virtualization(const char *parameter) {
 121         int r, b;
 122         const char *id;
 123
 124         assert(parameter);
 125
 126         r = detect_virtualization(&id);
 127         if (r < 0) {
 128                 log_warning("Failed to detect virtualization, ignoring: %s", strerror(-r));
 129                 return false;
 130         }
 131
 132         b = parse_boolean(parameter);
 133
 134         if (r > 0 && b > 0)
 135                 return true;
 136
 137         if (r == 0 && b == 0)
 138                 return true;
 139
 140         return streq(parameter, id);
 141 }
 142
 143 static bool test_security(const char *parameter) {
 144 #ifdef HAVE_SELINUX
 145         if (streq(parameter, "selinux"))
 146                 return is_selinux_enabled() > 0;
 147 #endif
 148         return false;
 149 }
 150
 151 bool condition_test(Condition *c) {
 152         assert(c);
 153
 154         switch(c->type) {
 155
 156         case CONDITION_PATH_EXISTS:
 157                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 158
 159         case CONDITION_PATH_EXISTS_GLOB:
 160                 return (glob_exists(c->parameter) > 0) == !c->negate;
 161
 162         case CONDITION_PATH_IS_DIRECTORY: {
 163                 struct stat st;
 164
 165                 if (lstat(c->parameter, &st) < 0)
 166                         return !c->negate;
 167                 return S_ISDIR(st.st_mode) == !c->negate;
 168         }
 169
 170         case CONDITION_PATH_IS_MOUNT_POINT:
 171                 return (path_is_mount_point(c->parameter, true) > 0) == !c->negate;
 172
 173         case CONDITION_DIRECTORY_NOT_EMPTY: {
 174                 int k;
 175
 176                 k = dir_is_empty(c->parameter);
 177                 return !(k == -ENOENT || k > 0) == !c->negate;
 178         }
 179
 180         case CONDITION_FILE_IS_EXECUTABLE: {
 181                 struct stat st;
 182
 183                 if (stat(c->parameter, &st) < 0)
 184                         return !c->negate;
 185
 186                 return (S_ISREG(st.st_mode) && (st.st_mode & 0111)) == !c->negate;
 187         }
 188
 189         case CONDITION_KERNEL_COMMAND_LINE:
 190                 return test_kernel_command_line(c->parameter) == !c->negate;
 191
 192         case CONDITION_VIRTUALIZATION:
 193                 return test_virtualization(c->parameter) == !c->negate;
 194
 195         case CONDITION_SECURITY:
 196                 return test_security(c->parameter) == !c->negate;
 197
 198         case CONDITION_NULL:
 199                 return !c->negate;
 200
 201         default:
 202                 assert_not_reached("Invalid condition type.");
 203         }
 204 }
 205
 206 bool condition_test_list(Condition *first) {
 207         Condition *c;
 208         int triggered = -1;
 209
 210         /* If the condition list is empty, then it is true */
 211         if (!first)
 212                 return true;
 213
 214         /* Otherwise, if all of the non-trigger conditions apply and
 215          * if any of the trigger conditions apply (unless there are
 216          * none) we return true */
 217         LIST_FOREACH(conditions, c, first) {
 218                 bool b;
 219
 220                 b = condition_test(c);
 221
 222                 if (!c->trigger && !b)
 223                         return false;
 224
 225                 if (c->trigger && triggered <= 0)
 226                         triggered = b;
 227         }
 228
 229         return triggered != 0;
 230 }
 231
 232 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 233         assert(c);
 234         assert(f);
 235
 236         if (!prefix)
 237                 prefix = "";
 238
 239         fprintf(f,
 240                 "%s\t%s: %s%s%s\n",
 241                 prefix,
 242                 condition_type_to_string(c->type),
 243                 c->trigger ? "|" : "",
 244                 c->negate ? "!" : "",
 245                 c->parameter);
 246 }
 247
 248 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 249         Condition *c;
 250
 251         LIST_FOREACH(conditions, c, first)
 252                 condition_dump(c, f, prefix);
 253 }
 254
 255 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 256         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 257         [CONDITION_PATH_EXISTS_GLOB] = "ConditionPathExistsGlob",
 258         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
 259         [CONDITION_PATH_IS_MOUNT_POINT] = "ConditionPathIsMountPoint",
 260         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
 261         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 262         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
 263         [CONDITION_SECURITY] = "ConditionSecurity",
 264         [CONDITION_NULL] = "ConditionNull"
 265 };
 266
 267 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);