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 (stat(c->parameter, &st) < 0)
 166                         return !c->negate;
 167                 return S_ISDIR(st.st_mode) == !c->negate;
 168         }
 169
 170         case CONDITION_PATH_IS_SYMBOLIC_LINK: {
 171                 struct stat st;
 172
 173                 if (lstat(c->parameter, &st) < 0)
 174                         return !c->negate;
 175                 return S_ISLNK(st.st_mode) == !c->negate;
 176         }
 177
 178         case CONDITION_PATH_IS_MOUNT_POINT:
 179                 return (path_is_mount_point(c->parameter, true) > 0) == !c->negate;
 180
 181         case CONDITION_DIRECTORY_NOT_EMPTY: {
 182                 int k;
 183
 184                 k = dir_is_empty(c->parameter);
 185                 return !(k == -ENOENT || k > 0) == !c->negate;
 186         }
 187
 188         case CONDITION_FILE_IS_EXECUTABLE: {
 189                 struct stat st;
 190
 191                 if (stat(c->parameter, &st) < 0)
 192                         return !c->negate;
 193
 194                 return (S_ISREG(st.st_mode) && (st.st_mode & 0111)) == !c->negate;
 195         }
 196
 197         case CONDITION_KERNEL_COMMAND_LINE:
 198                 return test_kernel_command_line(c->parameter) == !c->negate;
 199
 200         case CONDITION_VIRTUALIZATION:
 201                 return test_virtualization(c->parameter) == !c->negate;
 202
 203         case CONDITION_SECURITY:
 204                 return test_security(c->parameter) == !c->negate;
 205
 206         case CONDITION_NULL:
 207                 return !c->negate;
 208
 209         default:
 210                 assert_not_reached("Invalid condition type.");
 211         }
 212 }
 213
 214 bool condition_test_list(Condition *first) {
 215         Condition *c;
 216         int triggered = -1;
 217
 218         /* If the condition list is empty, then it is true */
 219         if (!first)
 220                 return true;
 221
 222         /* Otherwise, if all of the non-trigger conditions apply and
 223          * if any of the trigger conditions apply (unless there are
 224          * none) we return true */
 225         LIST_FOREACH(conditions, c, first) {
 226                 bool b;
 227
 228                 b = condition_test(c);
 229
 230                 if (!c->trigger && !b)
 231                         return false;
 232
 233                 if (c->trigger && triggered <= 0)
 234                         triggered = b;
 235         }
 236
 237         return triggered != 0;
 238 }
 239
 240 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 241         assert(c);
 242         assert(f);
 243
 244         if (!prefix)
 245                 prefix = "";
 246
 247         fprintf(f,
 248                 "%s\t%s: %s%s%s\n",
 249                 prefix,
 250                 condition_type_to_string(c->type),
 251                 c->trigger ? "|" : "",
 252                 c->negate ? "!" : "",
 253                 c->parameter);
 254 }
 255
 256 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 257         Condition *c;
 258
 259         LIST_FOREACH(conditions, c, first)
 260                 condition_dump(c, f, prefix);
 261 }
 262
 263 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 264         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 265         [CONDITION_PATH_EXISTS_GLOB] = "ConditionPathExistsGlob",
 266         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
 267         [CONDITION_PATH_IS_SYMBOLIC_LINK] = "ConditionPathIsSymbolicLink",
 268         [CONDITION_PATH_IS_MOUNT_POINT] = "ConditionPathIsMountPoint",
 269         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
 270         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 271         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
 272         [CONDITION_SECURITY] = "ConditionSecurity",
 273         [CONDITION_NULL] = "ConditionNull"
 274 };
 275
 276 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);