src/core/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 Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 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   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser 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 #include <sys/statvfs.h>
  28 #include <fnmatch.h>
  29
  30 #include "sd-id128.h"
  31 #include "util.h"
  32 #include "condition.h"
  33 #include "virt.h"
  34 #include "path-util.h"
  35 #include "fileio.h"
  36 #include "unit.h"
  37 #include "smack-util.h"
  38 #include "apparmor-util.h"
  39 #include "ima-util.h"
  40 #include "selinux-util.h"
  41
  42 static bool condition_test_security(Condition *c) {
  43         assert(c);
  44         assert(c->parameter);
  45         assert(c->type == CONDITION_SECURITY);
  46
  47         if (streq(c->parameter, "selinux"))
  48                 return use_selinux() == !c->negate;
  49         if (streq(c->parameter, "apparmor"))
  50                 return use_apparmor() == !c->negate;
  51         if (streq(c->parameter, "ima"))
  52                 return use_ima() == !c->negate;
  53         if (streq(c->parameter, "smack"))
  54                 return use_smack() == !c->negate;
  55
  56         return c->negate;
  57 }
  58
  59 static bool condition_test_capability(Condition *c) {
  60         _cleanup_fclose_ FILE *f = NULL;
  61         cap_value_t value;
  62         char line[LINE_MAX];
  63         unsigned long long capabilities = -1;
  64
  65         assert(c);
  66         assert(c->parameter);
  67         assert(c->type == CONDITION_CAPABILITY);
  68
  69         /* If it's an invalid capability, we don't have it */
  70
  71         if (cap_from_name(c->parameter, &value) < 0)
  72                 return c->negate;
  73
  74         /* If it's a valid capability we default to assume
  75          * that we have it */
  76
  77         f = fopen("/proc/self/status", "re");
  78         if (!f)
  79                 return !c->negate;
  80
  81         while (fgets(line, sizeof(line), f)) {
  82                 truncate_nl(line);
  83
  84                 if (startswith(line, "CapBnd:")) {
  85                         (void) sscanf(line+7, "%llx", &capabilities);
  86                         break;
  87                 }
  88         }
  89
  90         return !!(capabilities & (1ULL << value)) == !c->negate;
  91 }
  92
  93 static bool condition_test_needs_update(Condition *c) {
  94         const char *p;
  95         struct stat usr, other;
  96
  97         assert(c);
  98         assert(c->parameter);
  99         assert(c->type == CONDITION_NEEDS_UPDATE);
 100
 101         /* If the file system is read-only we shouldn't suggest an update */
 102         if (path_is_read_only_fs(c->parameter) > 0)
 103                 return c->negate;
 104
 105         /* Any other failure means we should allow the condition to be true,
 106          * so that we rather invoke too many update tools then too
 107          * few. */
 108
 109         if (!path_is_absolute(c->parameter))
 110                 return !c->negate;
 111
 112         p = strappenda(c->parameter, "/.updated");
 113         if (lstat(p, &other) < 0)
 114                 return !c->negate;
 115
 116         if (lstat("/usr/", &usr) < 0)
 117                 return !c->negate;
 118
 119         return (usr.st_mtim.tv_sec > other.st_mtim.tv_sec ||
 120                 (usr.st_mtim.tv_sec == other.st_mtim.tv_sec && usr.st_mtim.tv_nsec > other.st_mtim.tv_nsec)) == !c->negate;
 121 }
 122
 123 static bool condition_test_first_boot(Condition *c) {
 124         int r;
 125
 126         assert(c);
 127         assert(c->parameter);
 128         assert(c->type == CONDITION_FIRST_BOOT);
 129
 130         r = parse_boolean(c->parameter);
 131         if (r < 0)
 132                 return c->negate;
 133
 134         return ((access("/run/systemd/first-boot", F_OK) >= 0) == !!r) == !c->negate;
 135 }
 136
 137 static bool condition_test(Condition *c) {
 138         assert(c);
 139
 140         switch(c->type) {
 141
 142         case CONDITION_PATH_EXISTS:
 143                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 144
 145         case CONDITION_PATH_EXISTS_GLOB:
 146                 return (glob_exists(c->parameter) > 0) == !c->negate;
 147
 148         case CONDITION_PATH_IS_DIRECTORY: {
 149                 struct stat st;
 150
 151                 if (stat(c->parameter, &st) < 0)
 152                         return c->negate;
 153                 return S_ISDIR(st.st_mode) == !c->negate;
 154         }
 155
 156         case CONDITION_PATH_IS_SYMBOLIC_LINK: {
 157                 struct stat st;
 158
 159                 if (lstat(c->parameter, &st) < 0)
 160                         return c->negate;
 161                 return S_ISLNK(st.st_mode) == !c->negate;
 162         }
 163
 164         case CONDITION_PATH_IS_MOUNT_POINT:
 165                 return (path_is_mount_point(c->parameter, true) > 0) == !c->negate;
 166
 167         case CONDITION_PATH_IS_READ_WRITE:
 168                 return (path_is_read_only_fs(c->parameter) > 0) == c->negate;
 169
 170         case CONDITION_DIRECTORY_NOT_EMPTY: {
 171                 int k;
 172
 173                 k = dir_is_empty(c->parameter);
 174                 return !(k == -ENOENT || k > 0) == !c->negate;
 175         }
 176
 177         case CONDITION_FILE_NOT_EMPTY: {
 178                 struct stat st;
 179
 180                 if (stat(c->parameter, &st) < 0)
 181                         return c->negate;
 182
 183                 return (S_ISREG(st.st_mode) && st.st_size > 0) == !c->negate;
 184         }
 185
 186         case CONDITION_FILE_IS_EXECUTABLE: {
 187                 struct stat st;
 188
 189                 if (stat(c->parameter, &st) < 0)
 190                         return c->negate;
 191
 192                 return (S_ISREG(st.st_mode) && (st.st_mode & 0111)) == !c->negate;
 193         }
 194
 195         case CONDITION_KERNEL_COMMAND_LINE:
 196                 return condition_test_kernel_command_line(c);
 197
 198         case CONDITION_VIRTUALIZATION:
 199                 return condition_test_virtualization(c);
 200
 201         case CONDITION_SECURITY:
 202                 return condition_test_security(c);
 203
 204         case CONDITION_CAPABILITY:
 205                 return condition_test_capability(c);
 206
 207         case CONDITION_HOST:
 208                 return condition_test_host(c);
 209
 210         case CONDITION_AC_POWER:
 211                 return condition_test_ac_power(c);
 212
 213         case CONDITION_ARCHITECTURE:
 214                 return condition_test_architecture(c);
 215
 216         case CONDITION_NEEDS_UPDATE:
 217                 return condition_test_needs_update(c);
 218
 219         case CONDITION_FIRST_BOOT:
 220                 return condition_test_first_boot(c);
 221
 222         case CONDITION_NULL:
 223                 return !c->negate;
 224
 225         default:
 226                 assert_not_reached("Invalid condition type.");
 227         }
 228 }
 229
 230 bool condition_test_list(const char *unit, Condition *first) {
 231         Condition *c;
 232         int triggered = -1;
 233
 234         /* If the condition list is empty, then it is true */
 235         if (!first)
 236                 return true;
 237
 238         /* Otherwise, if all of the non-trigger conditions apply and
 239          * if any of the trigger conditions apply (unless there are
 240          * none) we return true */
 241         LIST_FOREACH(conditions, c, first) {
 242                 bool b;
 243
 244                 b = condition_test(c);
 245                 if (unit)
 246                         log_debug_unit(unit,
 247                                        "%s=%s%s%s %s for %s.",
 248                                        condition_type_to_string(c->type),
 249                                        c->trigger ? "|" : "",
 250                                        c->negate ? "!" : "",
 251                                        c->parameter,
 252                                        b ? "succeeded" : "failed",
 253                                        unit);
 254                 c->state = b ? 1 : -1;
 255
 256                 if (!c->trigger && !b)
 257                         return false;
 258
 259                 if (c->trigger && triggered <= 0)
 260                         triggered = b;
 261         }
 262
 263         return triggered != 0;
 264 }