From: Denys Vlasenko Date: Fri, 4 Aug 2017 21:04:17 +0000 (+0200) Subject: libbb: use _exit, not exit, in bb_daemonize_or_rexec() X-Git-Tag: 1_28_0~234 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=b182e9ad6011909fdb76358431d23d195febaf54;p=oweals%2Fbusybox.git libbb: use _exit, not exit, in bb_daemonize_or_rexec() By the time we reach exit in parent, child already exited or execed. We should not re-run libc cleanup code. While at it, introduce bb_daemon_helper() and add a few comments. Signed-off-by: Denys Vlasenko --- diff --git a/console-tools/openvt.c b/console-tools/openvt.c index f3db28367..423122fe9 100644 --- a/console-tools/openvt.c +++ b/console-tools/openvt.c @@ -99,7 +99,7 @@ static int find_free_vtno(void) /*xfunc_error_retval = 3; - do we need compat? */ if (ioctl(fd, VT_OPENQRY, &vtno) != 0 || vtno <= 0) bb_perror_msg_and_die("can't find open VT"); -// Not really needed, grep for DAEMON_ONLY_SANITIZE +// Not really needed, grep for DAEMON_CLOSE_EXTRA_FDS // if (fd > 2) // close(fd); return vtno; @@ -155,7 +155,7 @@ int openvt_main(int argc UNUSED_PARAM, char **argv) /* Grab new VT */ sprintf(vtname, VC_FORMAT, vtno); /* (Try to) clean up stray open fds above fd 2 */ - bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS | DAEMON_ONLY_SANITIZE, NULL); + bb_daemon_helper(DAEMON_CLOSE_EXTRA_FDS); close(STDIN_FILENO); /*setsid(); - BAD IDEA: after we exit, child is SIGHUPed... */ xopen(vtname, O_RDWR); diff --git a/debianutils/start_stop_daemon.c b/debianutils/start_stop_daemon.c index 9d60b2c7f..07c104baa 100644 --- a/debianutils/start_stop_daemon.c +++ b/debianutils/start_stop_daemon.c @@ -516,6 +516,11 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv) /* DAEMON_DEVNULL_STDIO is superfluous - * it's always done by bb_daemonize() */ #else + /* Daemons usually call bb_daemonize_or_rexec(), but SSD can do + * without: SSD is not itself a daemon, it _execs_ a daemon. + * The usual NOMMU problem of "child can't run indefinitely, + * it must exec" does not bite us: we exec anyway. + */ pid_t pid = xvfork(); if (pid != 0) { /* parent */ @@ -525,12 +530,8 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv) } /* Child */ setsid(); /* detach from controlling tty */ - /* Redirect stdio to /dev/null, close extra FDs. - * We do not actually daemonize because of DAEMON_ONLY_SANITIZE */ - bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO - + DAEMON_CLOSE_EXTRA_FDS - + DAEMON_ONLY_SANITIZE, - NULL /* argv, unused */ ); + /* Redirect stdio to /dev/null, close extra FDs */ + bb_daemon_helper(DAEMON_DEVNULL_STDIO + DAEMON_CLOSE_EXTRA_FDS); #endif } if (opt & OPT_MAKEPID) { diff --git a/include/libbb.h b/include/libbb.h index bb27c59a1..6a2a2d640 100644 --- a/include/libbb.h +++ b/include/libbb.h @@ -1169,6 +1169,7 @@ enum { #endif void bb_daemonize_or_rexec(int flags, char **argv) FAST_FUNC; void bb_sanitize_stdio(void) FAST_FUNC; +#define bb_daemon_helper(arg) bb_daemonize_or_rexec((arg) | DAEMON_ONLY_SANITIZE, NULL) /* Clear dangerous stuff, set PATH. Return 1 if was run by different user. */ int sanitize_env_if_suid(void) FAST_FUNC; diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c index 98512bb00..f84e678b5 100644 --- a/libbb/vfork_daemon_rexec.c +++ b/libbb/vfork_daemon_rexec.c @@ -209,6 +209,9 @@ pid_t FAST_FUNC fork_or_rexec(char **argv) /* Maybe we are already re-execed and come here again? */ if (re_execed) return 0; + + /* fflush_all(); ? - so far all callers had no buffered output to flush */ + pid = xvfork(); if (pid) /* parent */ return pid; @@ -245,8 +248,11 @@ void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv) fd = dup(fd); /* have 0,1,2 open at least to /dev/null */ if (!(flags & DAEMON_ONLY_SANITIZE)) { + + /* fflush_all(); - add it in fork_or_rexec() if necessary */ + if (fork_or_rexec(argv)) - exit(EXIT_SUCCESS); /* parent */ + _exit(EXIT_SUCCESS); /* parent */ /* if daemonizing, detach from stdio & ctty */ setsid(); dup2(fd, 0); @@ -258,7 +264,7 @@ void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv) * Prevent this: stop being a session leader. */ if (fork_or_rexec(argv)) - exit(EXIT_SUCCESS); /* parent */ + _exit(EXIT_SUCCESS); /* parent */ } } while (fd > 2) { diff --git a/loginutils/login.c b/loginutils/login.c index 381468d81..fcdb9592c 100644 --- a/loginutils/login.c +++ b/loginutils/login.c @@ -350,8 +350,8 @@ int login_main(int argc UNUSED_PARAM, char **argv) /* Mandatory paranoia for suid applet: * ensure that fd# 0,1,2 are opened (at least to /dev/null) * and any extra open fd's are closed. - * (The name of the function is misleading. Not daemonizing here.) */ - bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE | DAEMON_CLOSE_EXTRA_FDS, NULL); + */ + bb_daemon_helper(DAEMON_CLOSE_EXTRA_FDS); username[0] = '\0'; opt = getopt32(argv, "f:h:p", &opt_user, &opt_host); diff --git a/printutils/lpd.c b/printutils/lpd.c index 3fdba5d2b..662d3a224 100644 --- a/printutils/lpd.c +++ b/printutils/lpd.c @@ -198,9 +198,8 @@ int lpd_main(int argc UNUSED_PARAM, char *argv[]) q = p; // next line } // helper should not talk over network. - // this call reopens stdio fds to "/dev/null" - // (no daemonization is done) - bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO | DAEMON_ONLY_SANITIZE, NULL); + // this call reopens stdio fds to "/dev/null". + bb_daemon_helper(DAEMON_DEVNULL_STDIO); BB_EXECVP_or_die(argv); }