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 #include <sys/capability.h>
  27
  28 #ifdef HAVE_SELINUX
  29 #include <selinux/selinux.h>
  30 #endif
  31
  32 #include "util.h"
  33 #include "condition.h"
  34 #include "virt.h"
  35
  36 Condition* condition_new(ConditionType type, const char *parameter, bool trigger, bool negate) {
  37         Condition *c;
  38
  39         assert(type < _CONDITION_TYPE_MAX);
  40
  41         c = new0(Condition, 1);
  42         if (!c)
  43                 return NULL;
  44
  45         c->type = type;
  46         c->trigger = trigger;
  47         c->negate = negate;
  48
  49         if (parameter) {
  50                 c->parameter = strdup(parameter);
  51                 if (!c->parameter) {
  52                         free(c);
  53                         return NULL;
  54                 }
  55         }
  56
  57         return c;
  58 }
  59
  60 void condition_free(Condition *c) {
  61         assert(c);
  62
  63         free(c->parameter);
  64         free(c);
  65 }
  66
  67 void condition_free_list(Condition *first) {
  68         Condition *c, *n;
  69
  70         LIST_FOREACH_SAFE(conditions, c, n, first)
  71                 condition_free(c);
  72 }
  73
  74 static bool test_kernel_command_line(const char *parameter) {
  75         char *line, *w, *state, *word = NULL;
  76         bool equal;
  77         int r;
  78         size_t l, pl;
  79         bool found = false;
  80
  81         assert(parameter);
  82
  83         if (detect_container(NULL) > 0)
  84                 return false;
  85
  86         r = read_one_line_file("/proc/cmdline", &line);
  87         if (r < 0) {
  88                 log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
  89                 return false;
  90         }
  91
  92         equal = !!strchr(parameter, '=');
  93         pl = strlen(parameter);
  94
  95         FOREACH_WORD_QUOTED(w, l, line, state) {
  96
  97                 free(word);
  98                 word = strndup(w, l);
  99                 if (!word)
 100                         break;
 101
 102                 if (equal) {
 103                         if (streq(word, parameter)) {
 104                                 found = true;
 105                                 break;
 106                         }
 107                 } else {
 108                         if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
 109                                 found = true;
 110                                 break;
 111                         }
 112                 }
 113
 114         }
 115
 116         free(word);
 117         free(line);
 118
 119         return found;
 120 }
 121
 122 static bool test_virtualization(const char *parameter) {
 123         int b;
 124         Virtualization v;
 125         const char *id;
 126
 127         assert(parameter);
 128
 129         v = detect_virtualization(&id);
 130         if (v < 0) {
 131                 log_warning("Failed to detect virtualization, ignoring: %s", strerror(-v));
 132                 return false;
 133         }
 134
 135         /* First, compare with yes/no */
 136         b = parse_boolean(parameter);
 137
 138         if (v > 0 && b > 0)
 139                 return true;
 140
 141         if (v == 0 && b == 0)
 142                 return true;
 143
 144         /* Then, compare categorization */
 145         if (v == VIRTUALIZATION_VM && streq(parameter, "vm"))
 146                 return true;
 147
 148         if (v == VIRTUALIZATION_CONTAINER && streq(parameter, "container"))
 149                 return true;
 150
 151         /* Finally compare id */
 152         return v > 0 && streq(parameter, id);
 153 }
 154
 155 static bool test_security(const char *parameter) {
 156 #ifdef HAVE_SELINUX
 157         if (streq(parameter, "selinux"))
 158                 return is_selinux_enabled() > 0;
 159 #endif
 160         return false;
 161 }
 162
 163 static bool test_capability(const char *parameter) {
 164         cap_value_t value;
 165         FILE *f;
 166         char line[LINE_MAX];
 167         unsigned long long capabilities = (unsigned long long) -1;
 168
 169         /* If it's an invalid capability, we don't have it */
 170
 171         if (cap_from_name(parameter, &value) < 0)
 172                 return false;
 173
 174         /* If it's a valid capability we default to assume
 175          * that we have it */
 176
 177         f = fopen("/proc/self/status", "re");
 178         if (!f)
 179                 return true;
 180
 181         while (fgets(line, sizeof(line), f)) {
 182                 truncate_nl(line);
 183
 184                 if (startswith(line, "CapBnd:")) {
 185                         (void) sscanf(line+7, "%llx", &capabilities);
 186                         break;
 187                 }
 188         }
 189
 190         return !!(capabilities & (1ULL << value));
 191 }
 192
 193 bool condition_test(Condition *c) {
 194         assert(c);
 195
 196         switch(c->type) {
 197
 198         case CONDITION_PATH_EXISTS:
 199                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 200
 201         case CONDITION_PATH_EXISTS_GLOB:
 202                 return (glob_exists(c->parameter) > 0) == !c->negate;
 203
 204         case CONDITION_PATH_IS_DIRECTORY: {
 205                 struct stat st;
 206
 207                 if (stat(c->parameter, &st) < 0)
 208                         return c->negate;
 209                 return S_ISDIR(st.st_mode) == !c->negate;
 210         }
 211
 212         case CONDITION_PATH_IS_SYMBOLIC_LINK: {
 213                 struct stat st;
 214
 215                 if (lstat(c->parameter, &st) < 0)
 216                         return c->negate;
 217                 return S_ISLNK(st.st_mode) == !c->negate;
 218         }
 219
 220         case CONDITION_PATH_IS_MOUNT_POINT:
 221                 return (path_is_mount_point(c->parameter, true) > 0) == !c->negate;
 222
 223         case CONDITION_DIRECTORY_NOT_EMPTY: {
 224                 int k;
 225
 226                 k = dir_is_empty(c->parameter);
 227                 return !(k == -ENOENT || k > 0) == !c->negate;
 228         }
 229
 230         case CONDITION_FILE_IS_EXECUTABLE: {
 231                 struct stat st;
 232
 233                 if (stat(c->parameter, &st) < 0)
 234                         return c->negate;
 235
 236                 return (S_ISREG(st.st_mode) && (st.st_mode & 0111)) == !c->negate;
 237         }
 238
 239         case CONDITION_KERNEL_COMMAND_LINE:
 240                 return test_kernel_command_line(c->parameter) == !c->negate;
 241
 242         case CONDITION_VIRTUALIZATION:
 243                 return test_virtualization(c->parameter) == !c->negate;
 244
 245         case CONDITION_SECURITY:
 246                 return test_security(c->parameter) == !c->negate;
 247
 248         case CONDITION_CAPABILITY:
 249                 return test_capability(c->parameter) == !c->negate;
 250
 251         case CONDITION_NULL:
 252                 return !c->negate;
 253
 254         default:
 255                 assert_not_reached("Invalid condition type.");
 256         }
 257 }
 258
 259 bool condition_test_list(Condition *first) {
 260         Condition *c;
 261         int triggered = -1;
 262
 263         /* If the condition list is empty, then it is true */
 264         if (!first)
 265                 return true;
 266
 267         /* Otherwise, if all of the non-trigger conditions apply and
 268          * if any of the trigger conditions apply (unless there are
 269          * none) we return true */
 270         LIST_FOREACH(conditions, c, first) {
 271                 bool b;
 272
 273                 b = condition_test(c);
 274
 275                 if (!c->trigger && !b)
 276                         return false;
 277
 278                 if (c->trigger && triggered <= 0)
 279                         triggered = b;
 280         }
 281
 282         return triggered != 0;
 283 }
 284
 285 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 286         assert(c);
 287         assert(f);
 288
 289         if (!prefix)
 290                 prefix = "";
 291
 292         fprintf(f,
 293                 "%s\t%s: %s%s%s\n",
 294                 prefix,
 295                 condition_type_to_string(c->type),
 296                 c->trigger ? "|" : "",
 297                 c->negate ? "!" : "",
 298                 c->parameter);
 299 }
 300
 301 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 302         Condition *c;
 303
 304         LIST_FOREACH(conditions, c, first)
 305                 condition_dump(c, f, prefix);
 306 }
 307
 308 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 309         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 310         [CONDITION_PATH_EXISTS_GLOB] = "ConditionPathExistsGlob",
 311         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
 312         [CONDITION_PATH_IS_SYMBOLIC_LINK] = "ConditionPathIsSymbolicLink",
 313         [CONDITION_PATH_IS_MOUNT_POINT] = "ConditionPathIsMountPoint",
 314         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
 315         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 316         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
 317         [CONDITION_SECURITY] = "ConditionSecurity",
 318         [CONDITION_NULL] = "ConditionNull"
 319 };
 320
 321 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);