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