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 #include <execinfo.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 void sig_handler(int signo)
  29 {
  30         switch(signo) {
  31                 case SIGILL:
  32                 case SIGABRT:
  33                 case SIGFPE:
  34                 case SIGSEGV:
  35                 case SIGBUS:
  36                 case SIGSYS:
  37                 case SIGTRAP:
  38                 case SIGXCPU:
  39                 case SIGXFSZ:
  40                         infoerr("Death signaled exit (signal %d).", signo);
  41                         signal(signo, SIG_DFL);
  42                         break;
  43
  44                 case SIGKILL:
  45                 case SIGTERM:
  46                 case SIGQUIT:
  47                 case SIGINT:
  48                 case SIGHUP:
  49                 case SIGUSR1:
  50                 case SIGUSR2:
  51                         infoerr("Signaled exit (signal %d).", signo);
  52                         signal(SIGPIPE, SIG_IGN);
  53                         signal(SIGTERM, SIG_IGN);
  54                         signal(SIGQUIT, SIG_IGN);
  55                         signal(SIGHUP,  SIG_IGN);
  56                         signal(SIGINT,  SIG_IGN);
  57                         signal(SIGCHLD, SIG_IGN);
  58                         netdata_cleanup_and_exit(1);
  59                         break;
  60
  61                 case SIGPIPE:
  62                         infoerr("Signaled PIPE (signal %d).", signo);
  63                         // this is received when web clients send a reset
  64                         // no need to log it.
  65                         // infoerr("Ignoring signal %d.", signo);
  66                         break;
  67
  68                 default:
  69                         info("Signal %d received. Falling back to default action for it.", signo);
  70                         signal(signo, SIG_DFL);
  71                         break;
  72         }
  73 }
  74
  75 char rundir[FILENAME_MAX + 1] = "/var/run/netdata";
  76 char pidfile[FILENAME_MAX + 1] = "";
  77 void prepare_rundir() {
  78         if(getuid() != 0) {
  79                 mkdir("/run/user", 0775);
  80                 snprintf(rundir, FILENAME_MAX, "/run/user/%d", getuid());
  81                 mkdir(rundir, 0775);
  82                 snprintf(rundir, FILENAME_MAX, "/run/user/%d/netdata", getuid());
  83         }
  84
  85         snprintf(pidfile, FILENAME_MAX, "%s/netdata.pid", rundir);
  86
  87         if(mkdir(rundir, 0775) != 0) {
  88                 if(errno != EEXIST) error("Cannot create directory '%s'.", rundir);
  89         }
  90 }
  91
  92 int become_user(const char *username)
  93 {
  94         struct passwd *pw = getpwnam(username);
  95         if(!pw) {
  96                 error("User %s is not present.", username);
  97                 return -1;
  98         }
  99
 100         if(chown(rundir, pw->pw_uid, pw->pw_gid) != 0) {
 101                 error("Cannot chown directory '%s' to user %s.", rundir, username);
 102                 return -1;
 103         }
 104
 105         if(setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
 106                 error("Cannot switch to user's %s group (gid: %d).", username, pw->pw_gid);
 107                 return -1;
 108         }
 109
 110         if(setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) {
 111                 error("Cannot switch to user %s (uid: %d).", username, pw->pw_uid);
 112                 return -1;
 113         }
 114
 115         if(setgid(pw->pw_gid) != 0) {
 116                 error("Cannot switch to user's %s group (gid: %d).", username, pw->pw_gid);
 117                 return -1;
 118         }
 119         if(setegid(pw->pw_gid) != 0) {
 120                 error("Cannot effectively switch to user's %s group (gid: %d).", username, pw->pw_gid);
 121                 return -1;
 122         }
 123         if(setuid(pw->pw_uid) != 0) {
 124                 error("Cannot switch to user %s (uid: %d).", username, pw->pw_uid);
 125                 return -1;
 126         }
 127         if(seteuid(pw->pw_uid) != 0) {
 128                 error("Cannot effectively switch to user %s (uid: %d).", username, pw->pw_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 = -1;
 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 = 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         {
 298                 unlink(pidfile);
 299                 int fd = open(pidfile, O_RDWR | O_CREAT, 0666);
 300                 if(fd >= 0) {
 301                         char b[100];
 302                         sprintf(b, "%d\n", getpid());
 303                         int i = write(fd, b, strlen(b));
 304                         if(i <= 0) perror("Cannot write pid to file.");
 305                         close(fd);
 306                 }
 307         }
 308
 309         if(user && *user) {
 310                 if(become_user(user) != 0) {
 311                         error("Cannot become user '%s'. Continuing as we are.", user);
 312                 }
 313                 else info("Successfully became user '%s'.", user);
 314         }
 315
 316         return(0);
 317 }