X-Git-Url: http://git.ozlabs.org/?p=ppp.git;a=blobdiff_plain;f=pppd%2Fmain.c;h=7b57a2a570e6c771f2909f4c024ec3c5c93e9ba1;hp=2c2b8a2fcd853a4267c734f3af24e2c48bfe8596;hb=516eb9abe39cf49031bb1192232e6a49e96852fb;hpb=f53a48eb9d74db3c71938e114b7f489c339bc003 diff --git a/pppd/main.c b/pppd/main.c index 2c2b8a2..7b57a2a 100644 --- a/pppd/main.c +++ b/pppd/main.c @@ -40,7 +40,7 @@ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ -#define RCSID "$Id: main.c,v 1.120 2002/12/04 23:03:32 paulus Exp $" +#define RCSID "$Id: main.c,v 1.124 2003/03/04 05:37:22 fcusack Exp $" #include #include @@ -113,6 +113,7 @@ struct notifier *pidchange = NULL; struct notifier *phasechange = NULL; struct notifier *exitnotify = NULL; struct notifier *sigreceived = NULL; +struct notifier *fork_notifier = NULL; int hungup; /* terminal has been hung up */ int privileged; /* we're running as real uid root */ @@ -139,6 +140,7 @@ static int conn_running; /* we have a [dis]connector running */ static int devfd; /* fd of underlying device */ static int fd_ppp = -1; /* fd for talking PPP */ static int fd_loop; /* fd for getting demand-dial packets */ +static int fd_devnull; /* fd for /dev/null */ int phase; /* where the link is at */ int kill_link; @@ -190,8 +192,8 @@ static struct subprocess *children; /* Prototypes for procedures local to this file. */ static void setup_signals __P((void)); -static void create_pidfile __P((void)); -static void create_linkpidfile __P((void)); +static void create_pidfile __P((int pid)); +static void create_linkpidfile __P((int pid)); static void cleanup __P((void)); static void get_input __P((void)); static void calltimeout __P((void)); @@ -278,18 +280,6 @@ main(argc, argv) link_stats_valid = 0; new_phase(PHASE_INITIALIZE); - /* - * Ensure that fds 0, 1, 2 are open, to /dev/null if nowhere else. - * This way we can close 0, 1, 2 in detach() without clobbering - * a fd that we are using. - */ - if ((i = open("/dev/null", O_RDWR)) >= 0) { - while (0 <= i && i <= 2) - i = dup(i); - if (i >= 0) - close(i); - } - script_env = NULL; /* Initialize syslog facilities */ @@ -387,14 +377,6 @@ main(argc, argv) end_pr_log(); } - /* - * Early check for remote number authorization. - */ - if (!auth_number()) { - warn("calling number %q is not authorized", remote_number); - exit(EXIT_CNID_AUTH_FAILED); - } - if (dryrun) die(0); @@ -403,6 +385,17 @@ main(argc, argv) */ sys_init(); + /* Make sure fds 0, 1, 2 are open to somewhere. */ + fd_devnull = open(_PATH_DEVNULL, O_RDWR); + if (fd_devnull < 0) + fatal("Couldn't open %s: %m", _PATH_DEVNULL); + while (fd_devnull <= 2) { + i = dup(fd_devnull); + if (i < 0) + fatal("Critical shortage of file descriptors: dup failed: %m"); + fd_devnull = i; + } + #ifdef USE_TDB pppdb = tdb_open(_PATH_PPPDB, 0, 0, O_RDWR|O_CREAT, 0644); if (pppdb != NULL) { @@ -443,7 +436,7 @@ main(argc, argv) waiting = 0; - create_linkpidfile(); + create_linkpidfile(getpid()); /* * If we're doing dial-on-demand, set up the interface now. @@ -783,8 +776,8 @@ set_ifunit(iskey) slprintf(ifname, sizeof(ifname), "%s%d", PPP_DRV_NAME, ifunit); script_setenv("IFNAME", ifname, iskey); if (iskey) { - create_pidfile(); /* write pid to file */ - create_linkpidfile(); + create_pidfile(getpid()); /* write pid to file */ + create_linkpidfile(getpid()); } } @@ -796,9 +789,12 @@ detach() { int pid; char numbuf[16]; + int pipefd[2]; if (detached) return; + if (pipe(pipefd) == -1) + pipefd[0] = pipefd[1] = -1; if ((pid = fork()) < 0) { error("Couldn't detach (fork failed: %m)"); die(1); /* or just return? */ @@ -806,23 +802,28 @@ detach() if (pid != 0) { /* parent */ notify(pidchange, pid); + /* update pid files if they have been written already */ + if (pidfilename[0]) + create_pidfile(pid); + if (linkpidfile[0]) + create_linkpidfile(pid); exit(0); /* parent dies */ } setsid(); chdir("/"); - close(0); - close(1); - close(2); + dup2(fd_devnull, 0); + dup2(fd_devnull, 1); + dup2(fd_devnull, 2); detached = 1; if (log_default) log_to_fd = -1; - /* update pid files if they have been written already */ - if (pidfilename[0]) - create_pidfile(); - if (linkpidfile[0]) - create_linkpidfile(); slprintf(numbuf, sizeof(numbuf), "%d", getpid()); script_setenv("PPPD_PID", numbuf, 1); + + /* wait for parent to finish updating pid & lock files and die */ + close(pipefd[1]); + read(pipefd[0], numbuf, 1); + close(pipefd[0]); } /* @@ -843,7 +844,8 @@ reopen_log() * Create a file containing our process ID. */ static void -create_pidfile() +create_pidfile(pid) + int pid; { FILE *pidfile; @@ -859,7 +861,8 @@ create_pidfile() } static void -create_linkpidfile() +create_linkpidfile(pid) + int pid; { FILE *pidfile; @@ -1405,6 +1408,42 @@ bad_signal(sig) die(127); } +/* + * safe_fork - Create a child process. The child closes all the + * file descriptors that we don't want to leak to a script. + * The parent waits for the child to do this before returning. + */ +pid_t +safe_fork() +{ + pid_t pid; + int pipefd[2]; + char buf[1]; + + if (pipe(pipefd) == -1) + pipefd[0] = pipefd[1] = -1; + pid = fork(); + if (pid < 0) + return -1; + if (pid > 0) { + close(pipefd[1]); + /* this read() blocks until the close(pipefd[1]) below */ + while (read(pipefd[0], buf, 1) < 0) + if (errno != EINTR) + break; + close(pipefd[0]); + return pid; + } + sys_close(); +#ifdef USE_TDB + tdb_close(pppdb); +#endif + notify(fork_notifier, 0); + close(pipefd[0]); + /* this close unblocks the read() call above in the parent */ + close(pipefd[1]); + return 0; +} /* * device_script - run a program to talk to the specified fds @@ -1417,12 +1456,12 @@ device_script(program, in, out, dont_wait) int in, out; int dont_wait; { - int pid, fd; + int pid; int status = -1; int errfd; ++conn_running; - pid = fork(); + pid = safe_fork(); if (pid < 0) { --conn_running; @@ -1446,31 +1485,31 @@ device_script(program, in, out, dont_wait) } /* here we are executing in the child */ - /* make sure fds 0, 1, 2 are occupied */ - while ((fd = dup(in)) >= 0) { - if (fd > 2) { - close(fd); - break; - } - } /* dup in and out to fds > 2 */ - in = dup(in); - out = dup(out); - if (log_to_fd >= 0) { - errfd = dup(log_to_fd); - } else { - errfd = open(_PATH_CONNERRS, O_WRONLY | O_APPEND | O_CREAT, 0600); + { + int fd1 = in, fd2 = out, fd3 = log_to_fd; + + in = dup(in); + out = dup(out); + if (log_to_fd >= 0) { + errfd = dup(log_to_fd); + } else { + errfd = open(_PATH_CONNERRS, O_WRONLY | O_APPEND | O_CREAT, 0600); + } + close(fd1); + close(fd2); + close(fd3); } /* close fds 0 - 2 and any others we can think of */ close(0); close(1); close(2); - sys_close(); if (the_channel->close) (*the_channel->close)(); closelog(); + close(fd_devnull); /* dup the in, out, err fds to 0, 1, 2 */ dup2(in, 0); @@ -1530,66 +1569,54 @@ run_program(prog, args, must_exist, done, arg) return 0; } - pid = fork(); + pid = safe_fork(); if (pid == -1) { error("Failed to create child process for %s: %m", prog); return -1; } - if (pid == 0) { - int new_fd; + if (pid != 0) { + if (debug) + dbglog("Script %s started (pid %d)", prog, pid); + record_child(pid, prog, done, arg); + return pid; + } - /* Leave the current location */ - (void) setsid(); /* No controlling tty. */ - (void) umask (S_IRWXG|S_IRWXO); - (void) chdir ("/"); /* no current directory. */ - setuid(0); /* set real UID = root */ - setgid(getegid()); + /* Leave the current location */ + (void) setsid(); /* No controlling tty. */ + (void) umask (S_IRWXG|S_IRWXO); + (void) chdir ("/"); /* no current directory. */ + setuid(0); /* set real UID = root */ + setgid(getegid()); - /* Ensure that nothing of our device environment is inherited. */ - sys_close(); - closelog(); - close (0); - close (1); - close (2); - if (the_channel->close) - (*the_channel->close)(); - - /* Don't pass handles to the PPP device, even by accident. */ - new_fd = open (_PATH_DEVNULL, O_RDWR); - if (new_fd >= 0) { - if (new_fd != 0) { - dup2 (new_fd, 0); /* stdin <- /dev/null */ - close (new_fd); - } - dup2 (0, 1); /* stdout -> /dev/null */ - dup2 (0, 2); /* stderr -> /dev/null */ - } + /* Ensure that nothing of our device environment is inherited. */ + closelog(); + if (the_channel->close) + (*the_channel->close)(); + + /* Don't pass handles to the PPP device, even by accident. */ + dup2(fd_devnull, 0); + dup2(fd_devnull, 1); + dup2(fd_devnull, 2); + close(fd_devnull); #ifdef BSD - /* Force the priority back to zero if pppd is running higher. */ - if (setpriority (PRIO_PROCESS, 0, 0) < 0) - warn("can't reset priority to 0: %m"); + /* Force the priority back to zero if pppd is running higher. */ + if (setpriority (PRIO_PROCESS, 0, 0) < 0) + warn("can't reset priority to 0: %m"); #endif - /* SysV recommends a second fork at this point. */ + /* SysV recommends a second fork at this point. */ - /* run the program */ - execve(prog, args, script_env); - if (must_exist || errno != ENOENT) { - /* have to reopen the log, there's nowhere else - for the message to go. */ - reopen_log(); - syslog(LOG_ERR, "Can't execute %s: %m", prog); - closelog(); - } - _exit(-1); + /* run the program */ + execve(prog, args, script_env); + if (must_exist || errno != ENOENT) { + /* have to reopen the log, there's nowhere else + for the message to go. */ + reopen_log(); + syslog(LOG_ERR, "Can't execute %s: %m", prog); + closelog(); } - - if (debug) - dbglog("Script %s started (pid %d)", prog, pid); - record_child(pid, prog, done, arg); - - return pid; + _exit(-1); }