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 #include "virt.h"
  34
  35 Condition* condition_new(ConditionType type, const char *parameter, bool trigger, bool negate) {
  36         Condition *c;
  37
  38         assert(type < _CONDITION_TYPE_MAX);
  39
  40         c = new0(Condition, 1);
  41         if (!c)
  42                 return NULL;
  43
  44         c->type = type;
  45         c->trigger = trigger;
  46         c->negate = negate;
  47
  48         if (parameter) {
  49                 c->parameter = strdup(parameter);
  50                 if (!c->parameter) {
  51                         free(c);
  52                         return NULL;
  53                 }
  54         }
  55
  56         return c;
  57 }
  58
  59 void condition_free(Condition *c) {
  60         assert(c);
  61
  62         free(c->parameter);
  63         free(c);
  64 }
  65
  66 void condition_free_list(Condition *first) {
  67         Condition *c, *n;
  68
  69         LIST_FOREACH_SAFE(conditions, c, n, first)
  70                 condition_free(c);
  71 }
  72
  73 static bool test_kernel_command_line(const char *parameter) {
  74         char *line, *w, *state, *word = NULL;
  75         bool equal;
  76         int r;
  77         size_t l, pl;
  78         bool found = false;
  79
  80         assert(parameter);
  81
  82         if (detect_container(NULL) > 0)
  83                 return false;
  84
  85         r = read_one_line_file("/proc/cmdline", &line);
  86         if (r < 0) {
  87                 log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
  88                 return false;
  89         }
  90
  91         equal = !!strchr(parameter, '=');
  92         pl = strlen(parameter);
  93
  94         FOREACH_WORD_QUOTED(w, l, line, state) {
  95
  96                 free(word);
  97                 word = strndup(w, l);
  98                 if (!word)
  99                         break;
 100
 101                 if (equal) {
 102                         if (streq(word, parameter)) {
 103                                 found = true;
 104                                 break;
 105                         }
 106                 } else {
 107                         if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
 108                                 found = true;
 109                                 break;
 110                         }
 111                 }
 112
 113         }
 114
 115         free(word);
 116         free(line);
 117
 118         return found;
 119 }
 120
 121 static bool test_virtualization(const char *parameter) {
 122         int b;
 123         Virtualization v;
 124         const char *id;
 125
 126         assert(parameter);
 127
 128         v = detect_virtualization(&id);
 129         if (v < 0) {
 130                 log_warning("Failed to detect virtualization, ignoring: %s", strerror(-v));
 131                 return false;
 132         }
 133
 134         /* First, compare with yes/no */
 135         b = parse_boolean(parameter);
 136
 137         if (v > 0 && b > 0)
 138                 return true;
 139
 140         if (v == 0 && b == 0)
 141                 return true;
 142
 143         /* Then, compare categorization */
 144         if (v == VIRTUALIZATION_VM && streq(parameter, "vm"))
 145                 return true;
 146
 147         if (v == VIRTUALIZATION_CONTAINER && streq(parameter, "container"))
 148                 return true;
 149
 150         /* Finally compare id */
 151         return streq(parameter, id);
 152 }
 153
 154 static bool test_security(const char *parameter) {
 155 #ifdef HAVE_SELINUX
 156         if (streq(parameter, "selinux"))
 157                 return is_selinux_enabled() > 0;
 158 #endif
 159         return false;
 160 }
 161
 162 bool condition_test(Condition *c) {
 163         assert(c);
 164
 165         switch(c->type) {
 166
 167         case CONDITION_PATH_EXISTS:
 168                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 169
 170         case CONDITION_PATH_EXISTS_GLOB:
 171                 return (glob_exists(c->parameter) > 0) == !c->negate;
 172
 173         case CONDITION_PATH_IS_DIRECTORY: {
 174                 struct stat st;
 175
 176                 if (stat(c->parameter, &st) < 0)
 177                         return c->negate;
 178                 return S_ISDIR(st.st_mode) == !c->negate;
 179         }
 180
 181         case CONDITION_PATH_IS_SYMBOLIC_LINK: {
 182                 struct stat st;
 183
 184                 if (lstat(c->parameter, &st) < 0)
 185                         return c->negate;
 186                 return S_ISLNK(st.st_mode) == !c->negate;
 187         }
 188
 189         case CONDITION_PATH_IS_MOUNT_POINT:
 190                 return (path_is_mount_point(c->parameter, true) > 0) == !c->negate;
 191
 192         case CONDITION_DIRECTORY_NOT_EMPTY: {
 193                 int k;
 194
 195                 k = dir_is_empty(c->parameter);
 196                 return !(k == -ENOENT || k > 0) == !c->negate;
 197         }
 198
 199         case CONDITION_FILE_IS_EXECUTABLE: {
 200                 struct stat st;
 201
 202                 if (stat(c->parameter, &st) < 0)
 203                         return c->negate;
 204
 205                 return (S_ISREG(st.st_mode) && (st.st_mode & 0111)) == !c->negate;
 206         }
 207
 208         case CONDITION_KERNEL_COMMAND_LINE:
 209                 return test_kernel_command_line(c->parameter) == !c->negate;
 210
 211         case CONDITION_VIRTUALIZATION:
 212                 return test_virtualization(c->parameter) == !c->negate;
 213
 214         case CONDITION_SECURITY:
 215                 return test_security(c->parameter) == !c->negate;
 216
 217         case CONDITION_NULL:
 218                 return !c->negate;
 219
 220         default:
 221                 assert_not_reached("Invalid condition type.");
 222         }
 223 }
 224
 225 bool condition_test_list(Condition *first) {
 226         Condition *c;
 227         int triggered = -1;
 228
 229         /* If the condition list is empty, then it is true */
 230         if (!first)
 231                 return true;
 232
 233         /* Otherwise, if all of the non-trigger conditions apply and
 234          * if any of the trigger conditions apply (unless there are
 235          * none) we return true */
 236         LIST_FOREACH(conditions, c, first) {
 237                 bool b;
 238
 239                 b = condition_test(c);
 240
 241                 if (!c->trigger && !b)
 242                         return false;
 243
 244                 if (c->trigger && triggered <= 0)
 245                         triggered = b;
 246         }
 247
 248         return triggered != 0;
 249 }
 250
 251 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 252         assert(c);
 253         assert(f);
 254
 255         if (!prefix)
 256                 prefix = "";
 257
 258         fprintf(f,
 259                 "%s\t%s: %s%s%s\n",
 260                 prefix,
 261                 condition_type_to_string(c->type),
 262                 c->trigger ? "|" : "",
 263                 c->negate ? "!" : "",
 264                 c->parameter);
 265 }
 266
 267 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 268         Condition *c;
 269
 270         LIST_FOREACH(conditions, c, first)
 271                 condition_dump(c, f, prefix);
 272 }
 273
 274 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 275         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 276         [CONDITION_PATH_EXISTS_GLOB] = "ConditionPathExistsGlob",
 277         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
 278         [CONDITION_PATH_IS_SYMBOLIC_LINK] = "ConditionPathIsSymbolicLink",
 279         [CONDITION_PATH_IS_MOUNT_POINT] = "ConditionPathIsMountPoint",
 280         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
 281         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 282         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
 283         [CONDITION_SECURITY] = "ConditionSecurity",
 284         [CONDITION_NULL] = "ConditionNull"
 285 };
 286
 287 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);