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         if (!(c = new0(Condition, 1)))
  40                 return NULL;
  41
  42         c->type = type;
  43         c->trigger = trigger;
  44         c->negate = negate;
  45
  46         if (parameter)
  47                 if (!(c->parameter = strdup(parameter))) {
  48                         free(c);
  49                         return NULL;
  50                 }
  51
  52         return c;
  53 }
  54
  55 void condition_free(Condition *c) {
  56         assert(c);
  57
  58         free(c->parameter);
  59         free(c);
  60 }
  61
  62 void condition_free_list(Condition *first) {
  63         Condition *c, *n;
  64
  65         LIST_FOREACH_SAFE(conditions, c, n, first)
  66                 condition_free(c);
  67 }
  68
  69 static bool test_kernel_command_line(const char *parameter) {
  70         char *line, *w, *state, *word = NULL;
  71         bool equal;
  72         int r;
  73         size_t l, pl;
  74         bool found = false;
  75
  76         assert(parameter);
  77
  78         if (detect_virtualization(NULL) > 0)
  79                 return false;
  80
  81         if ((r = read_one_line_file("/proc/cmdline", &line)) < 0) {
  82                 log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
  83                 return false;
  84         }
  85
  86         equal = !!strchr(parameter, '=');
  87         pl = strlen(parameter);
  88
  89         FOREACH_WORD_QUOTED(w, l, line, state) {
  90
  91                 free(word);
  92                 if (!(word = strndup(w, l)))
  93                         break;
  94
  95                 if (equal) {
  96                         if (streq(word, parameter)) {
  97                                 found = true;
  98                                 break;
  99                         }
 100                 } else {
 101                         if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
 102                                 found = true;
 103                                 break;
 104                         }
 105                 }
 106
 107         }
 108
 109         free(word);
 110         free(line);
 111
 112         return found;
 113 }
 114
 115 static bool test_virtualization(const char *parameter) {
 116         int r, b;
 117         const char *id;
 118
 119         assert(parameter);
 120
 121         if ((r = detect_virtualization(&id)) < 0) {
 122                 log_warning("Failed to detect virtualization, ignoring: %s", strerror(-r));
 123                 return false;
 124         }
 125
 126         b = parse_boolean(parameter);
 127
 128         if (r > 0 && b > 0)
 129                 return true;
 130
 131         if (r == 0 && b == 0)
 132                 return true;
 133
 134         return streq(parameter, id);
 135 }
 136
 137 static bool test_security(const char *parameter) {
 138 #ifdef HAVE_SELINUX
 139         if (streq(parameter, "selinux"))
 140                 return is_selinux_enabled() > 0;
 141 #endif
 142         return false;
 143 }
 144
 145 bool condition_test(Condition *c) {
 146         assert(c);
 147
 148         switch(c->type) {
 149
 150         case CONDITION_PATH_EXISTS:
 151                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 152
 153         case CONDITION_PATH_EXISTS_GLOB:
 154                 return (glob_exists(c->parameter) > 0) == !c->negate;
 155
 156         case CONDITION_PATH_IS_DIRECTORY: {
 157                 struct stat st;
 158
 159                 if (lstat(c->parameter, &st) < 0)
 160                         return !c->negate;
 161                 return S_ISDIR(st.st_mode) == !c->negate;
 162         }
 163
 164         case CONDITION_DIRECTORY_NOT_EMPTY: {
 165                 int k;
 166
 167                 k = dir_is_empty(c->parameter);
 168                 return !(k == -ENOENT || k > 0) == !c->negate;
 169         }
 170
 171         case CONDITION_FILE_IS_EXECUTABLE: {
 172                 struct stat st;
 173
 174                 if (lstat(c->parameter, &st) < 0)
 175                         return !c->negate;
 176
 177                 return (S_ISREG(st.st_mode) && (st.st_mode & 0111)) == !c->negate;
 178         }
 179
 180         case CONDITION_KERNEL_COMMAND_LINE:
 181                 return test_kernel_command_line(c->parameter) == !c->negate;
 182
 183         case CONDITION_VIRTUALIZATION:
 184                 return test_virtualization(c->parameter) == !c->negate;
 185
 186         case CONDITION_SECURITY:
 187                 return test_security(c->parameter) == !c->negate;
 188
 189         case CONDITION_NULL:
 190                 return !c->negate;
 191
 192         default:
 193                 assert_not_reached("Invalid condition type.");
 194         }
 195 }
 196
 197 bool condition_test_list(Condition *first) {
 198         Condition *c;
 199         int triggered = -1;
 200
 201         /* If the condition list is empty, then it is true */
 202         if (!first)
 203                 return true;
 204
 205         /* Otherwise, if all of the non-trigger conditions apply and
 206          * if any of the trigger conditions apply (unless there are
 207          * none) we return true */
 208         LIST_FOREACH(conditions, c, first) {
 209                 bool b;
 210
 211                 b = condition_test(c);
 212
 213                 if (!c->trigger && !b)
 214                         return false;
 215
 216                 if (c->trigger && triggered <= 0)
 217                         triggered = b;
 218         }
 219
 220         return triggered != 0;
 221 }
 222
 223 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 224         assert(c);
 225         assert(f);
 226
 227         if (!prefix)
 228                 prefix = "";
 229
 230         fprintf(f,
 231                 "%s\t%s: %s%s%s\n",
 232                 prefix,
 233                 condition_type_to_string(c->type),
 234                 c->trigger ? "|" : "",
 235                 c->negate ? "!" : "",
 236                 c->parameter);
 237 }
 238
 239 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 240         Condition *c;
 241
 242         LIST_FOREACH(conditions, c, first)
 243                 condition_dump(c, f, prefix);
 244 }
 245
 246 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 247         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 248         [CONDITION_PATH_EXISTS_GLOB] = "ConditionPathExistsGlob",
 249         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
 250         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
 251         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 252         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
 253         [CONDITION_SECURITY] = "ConditionSecurity",
 254         [CONDITION_NULL] = "ConditionNull"
 255 };
 256
 257 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);