src/daemon.c

   1 #ifdef HAVE_CONFIG_H
   2 #include <config.h>
   3 #endif
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <unistd.h>
   7 #include <fcntl.h>
   8 #include <errno.h>
   9 #include <signal.h>
  10 #include <string.h>
  11 #include <sys/types.h>
  12 #include <pwd.h>
  13 #include <grp.h>
  14 #include <pthread.h>
  15 #include <sys/wait.h>
  16 #include <sys/stat.h>
  17
  18 #include "common.h"
  19 #include "appconfig.h"
  20 #include "log.h"
  21 #include "web_client.h"
  22 #include "plugins_d.h"
  23 #include "rrd.h"
  24 #include "popen.h"
  25 #include "main.h"
  26 #include "daemon.h"
  27
  28 char pidfile[FILENAME_MAX + 1] = "";
  29 int pidfd = -1;
  30
  31 void sig_handler(int signo)
  32 {
  33         switch(signo) {
  34                 case SIGILL:
  35                 case SIGABRT:
  36                 case SIGFPE:
  37                 case SIGSEGV:
  38                 case SIGBUS:
  39                 case SIGSYS:
  40                 case SIGTRAP:
  41                 case SIGXCPU:
  42                 case SIGXFSZ:
  43                         infoerr("Death signaled exit (signal %d).", signo);
  44                         signal(signo, SIG_DFL);
  45                         break;
  46
  47                 case SIGKILL:
  48                 case SIGTERM:
  49                 case SIGQUIT:
  50                 case SIGINT:
  51                 case SIGHUP:
  52                 case SIGUSR1:
  53                 case SIGUSR2:
  54                         infoerr("Signaled exit (signal %d).", signo);
  55                         signal(SIGPIPE, SIG_IGN);
  56                         signal(SIGTERM, SIG_IGN);
  57                         signal(SIGQUIT, SIG_IGN);
  58                         signal(SIGHUP,  SIG_IGN);
  59                         signal(SIGINT,  SIG_IGN);
  60                         signal(SIGCHLD, SIG_IGN);
  61                         netdata_cleanup_and_exit(1);
  62                         break;
  63
  64                 case SIGPIPE:
  65                         infoerr("Signaled PIPE (signal %d).", signo);
  66                         // this is received when web clients send a reset
  67                         // no need to log it.
  68                         // infoerr("Ignoring signal %d.", signo);
  69                         break;
  70
  71                 default:
  72                         info("Signal %d received. Falling back to default action for it.", signo);
  73                         signal(signo, SIG_DFL);
  74                         break;
  75         }
  76 }
  77
  78 int become_user(const char *username)
  79 {
  80         struct passwd *pw = getpwnam(username);
  81         if(!pw) {
  82                 error("User %s is not present.", username);
  83                 return -1;
  84         }
  85
  86         uid_t uid = pw->pw_uid;
  87         gid_t gid = pw->pw_gid;
  88
  89         int ngroups =  sysconf(_SC_NGROUPS_MAX);
  90         gid_t *supplementary_groups = NULL;
  91         if(ngroups) {
  92                 supplementary_groups = malloc(sizeof(gid_t) * ngroups);
  93                 if(supplementary_groups) {
  94                         if(getgrouplist(username, gid, supplementary_groups, &ngroups) == -1) {
  95                                 error("Cannot get supplementary groups of user '%s'.", username);
  96                                 free(supplementary_groups);
  97                                 supplementary_groups = NULL;
  98                                 ngroups = 0;
  99                         }
 100                 }
 101                 else fatal("Cannot allocate memory for %d supplementary groups", ngroups);
 102         }
 103
 104         if(pidfile[0] && getuid() != uid) {
 105                 // we are dropping privileges
 106                 if(chown(pidfile, uid, gid) != 0)
 107                         error("Cannot chown pidfile '%s' to user '%s'", pidfile, username);
 108
 109                 else if(pidfd != -1) {
 110                         // not need to keep it open
 111                         close(pidfd);
 112                         pidfd = -1;
 113                 }
 114         }
 115         else if(pidfd != -1) {
 116                 // not need to keep it open
 117                 close(pidfd);
 118                 pidfd = -1;
 119         }
 120
 121         if(supplementary_groups && ngroups) {
 122                 if(setgroups(ngroups, supplementary_groups) == -1)
 123                         error("Cannot set supplementary groups for user '%s'", username);
 124
 125                 free(supplementary_groups);
 126                 supplementary_groups = NULL;
 127                 ngroups = 0;
 128         }
 129
 130         if(setresgid(gid, gid, gid) != 0) {
 131                 error("Cannot switch to user's %s group (gid: %d).", username, gid);
 132                 return -1;
 133         }
 134
 135         if(setresuid(uid, uid, uid) != 0) {
 136                 error("Cannot switch to user %s (uid: %d).", username, uid);
 137                 return -1;
 138         }
 139
 140         if(setgid(gid) != 0) {
 141                 error("Cannot switch to user's %s group (gid: %d).", username, gid);
 142                 return -1;
 143         }
 144         if(setegid(gid) != 0) {
 145                 error("Cannot effectively switch to user's %s group (gid: %d).", username, gid);
 146                 return -1;
 147         }
 148         if(setuid(uid) != 0) {
 149                 error("Cannot switch to user %s (uid: %d).", username, uid);
 150                 return -1;
 151         }
 152         if(seteuid(uid) != 0) {
 153                 error("Cannot effectively switch to user %s (uid: %d).", username, uid);
 154                 return -1;
 155         }
 156
 157         return(0);
 158 }
 159
 160 int become_daemon(int dont_fork, int close_all_files, const char *user, const char *input, const char *output, const char *error, const char *access, int *access_fd, FILE **access_fp)
 161 {
 162         fflush(NULL);
 163
 164         // open the files before forking
 165         int input_fd = -1, output_fd = -1, error_fd = -1, dev_null;
 166
 167         if(input && *input) {
 168                 if((input_fd = open(input, O_RDONLY, 0666)) == -1) {
 169                         error("Cannot open input file '%s'.", input);
 170                         return -1;
 171                 }
 172         }
 173
 174         if(output && *output) {
 175                 if((output_fd = open(output, O_RDWR | O_APPEND | O_CREAT, 0666)) == -1) {
 176                         error("Cannot open output log file '%s'", output);
 177                         if(input_fd != -1) close(input_fd);
 178                         return -1;
 179                 }
 180         }
 181
 182         if(error && *error) {
 183                 if((error_fd = open(error, O_RDWR | O_APPEND | O_CREAT, 0666)) == -1) {
 184                         error("Cannot open error log file '%s'.", error);
 185                         if(input_fd != -1) close(input_fd);
 186                         if(output_fd != -1) close(output_fd);
 187                         return -1;
 188                 }
 189         }
 190
 191         if(access && *access && access_fd) {
 192                 if((*access_fd = open(access, O_RDWR | O_APPEND | O_CREAT, 0666)) == -1) {
 193                         error("Cannot open access log file '%s'", access);
 194                         if(input_fd != -1) close(input_fd);
 195                         if(output_fd != -1) close(output_fd);
 196                         if(error_fd != -1) close(error_fd);
 197                         return -1;
 198                 }
 199
 200                 if(access_fp) {
 201                         *access_fp = fdopen(*access_fd, "w");
 202                         if(!*access_fp) {
 203                                 error("Cannot migrate file's '%s' fd %d.", access, *access_fd);
 204                                 if(input_fd != -1) close(input_fd);
 205                                 if(output_fd != -1) close(output_fd);
 206                                 if(error_fd != -1) close(error_fd);
 207                                 close(*access_fd);
 208                                 *access_fd = -1;
 209                                 return -1;
 210                         }
 211                 }
 212         }
 213
 214         if((dev_null = open("/dev/null", O_RDWR, 0666)) == -1) {
 215                 perror("Cannot open /dev/null");
 216                 if(input_fd != -1) close(input_fd);
 217                 if(output_fd != -1) close(output_fd);
 218                 if(error_fd != -1) close(error_fd);
 219                 if(access && access_fd && *access_fd != -1) {
 220                         close(*access_fd);
 221                         *access_fd = -1;
 222                         if(access_fp) {
 223                                 fclose(*access_fp);
 224                                 *access_fp = NULL;
 225                         }
 226                 }
 227                 return -1;
 228         }
 229
 230         // all files opened
 231         // lets do it
 232
 233         if(!dont_fork) {
 234                 int i = fork();
 235                 if(i == -1) {
 236                         perror("cannot fork");
 237                         exit(1);
 238                 }
 239                 if(i != 0) {
 240                         exit(0); // the parent
 241                 }
 242
 243                 // become session leader
 244                 if (setsid() < 0) {
 245                         perror("Cannot become session leader.");
 246                         exit(2);
 247                 }
 248         }
 249
 250         signal(SIGCHLD,  SIG_IGN);
 251         signal(SIGHUP,   SIG_IGN);
 252         signal(SIGWINCH, SIG_IGN);
 253
 254         // fork() again
 255         if(!dont_fork) {
 256                 int i = fork();
 257                 if(i == -1) {
 258                         perror("cannot fork");
 259                         exit(1);
 260                 }
 261                 if(i != 0) {
 262                         exit(0); // the parent
 263                 }
 264         }
 265
 266         // Set new file permissions
 267         umask(0);
 268
 269         // close all files
 270         if(close_all_files) {
 271                 int i;
 272                 for(i = (int) (sysconf(_SC_OPEN_MAX) - 1); i > 0; i--)
 273                         if(
 274                                 ((access_fd && i != *access_fd) || !access_fd)
 275                                 && i != dev_null
 276                                 && i != input_fd
 277                                 && i != output_fd
 278                                 && i != error_fd
 279                                 && fd_is_valid(i)
 280                                 ) close(i);
 281         }
 282         else {
 283                 close(STDIN_FILENO);
 284                 close(STDOUT_FILENO);
 285                 close(STDERR_FILENO);
 286         }
 287
 288         // put the opened files
 289         // to our standard file descriptors
 290         if(input_fd != -1) {
 291                 if(input_fd != STDIN_FILENO) {
 292                         dup2(input_fd, STDIN_FILENO);
 293                         close(input_fd);
 294                 }
 295                 input_fd = -1;
 296         }
 297         else dup2(dev_null, STDIN_FILENO);
 298
 299         if(output_fd != -1) {
 300                 if(output_fd != STDOUT_FILENO) {
 301                         dup2(output_fd, STDOUT_FILENO);
 302                         close(output_fd);
 303                 }
 304                 output_fd = -1;
 305         }
 306         else dup2(dev_null, STDOUT_FILENO);
 307
 308         if(error_fd != -1) {
 309                 if(error_fd != STDERR_FILENO) {
 310                         dup2(error_fd, STDERR_FILENO);
 311                         close(error_fd);
 312                 }
 313                 error_fd = -1;
 314         }
 315         else dup2(dev_null, STDERR_FILENO);
 316
 317         // close /dev/null
 318         if(dev_null != STDIN_FILENO && dev_null != STDOUT_FILENO && dev_null != STDERR_FILENO)
 319                 close(dev_null);
 320
 321         // generate our pid file
 322         if(pidfile[0]) {
 323                 pidfd = open(pidfile, O_RDWR | O_CREAT, 0644);
 324                 if(pidfd >= 0) {
 325                         if(ftruncate(pidfd, 0) != 0)
 326                                 error("Cannot truncate pidfile '%s'.", pidfile);
 327
 328                         char b[100];
 329                         sprintf(b, "%d\n", getpid());
 330                         ssize_t i = write(pidfd, b, strlen(b));
 331                         if(i <= 0)
 332                                 error("Cannot write pidfile '%s'.", pidfile);
 333
 334                         // don't close it, we might need it at exit
 335                         // close(pidfd);
 336                 }
 337                 else error("Failed to open pidfile '%s'.", pidfile);
 338         }
 339
 340         if(user && *user) {
 341                 if(become_user(user) != 0) {
 342                         error("Cannot become user '%s'. Continuing as we are.", user);
 343                 }
 344                 else info("Successfully became user '%s'.", user);
 345         }
 346         else if(pidfd != -1)
 347                 close(pidfd);
 348
 349         return(0);
 350 }