diff options
Diffstat (limited to 'contrib/ntp/ntpd/ntpd.c')
| -rw-r--r-- | contrib/ntp/ntpd/ntpd.c | 104 |
1 files changed, 91 insertions, 13 deletions
diff --git a/contrib/ntp/ntpd/ntpd.c b/contrib/ntp/ntpd/ntpd.c index 529e6ce..a517391 100644 --- a/contrib/ntp/ntpd/ntpd.c +++ b/contrib/ntp/ntpd/ntpd.c @@ -27,6 +27,14 @@ #include "ntp_libopts.h" #include "ntpd-opts.h" +/* there's a short treatise below what the thread stuff is for */ +#if defined(HAVE_PTHREADS) && HAVE_PTHREADS && !defined(NO_THREADS) +# ifdef HAVE_PTHREAD_H +# include <pthread.h> +# endif +# define NEED_PTHREAD_WARMUP +#endif + #ifdef HAVE_UNISTD_H # include <unistd.h> #endif @@ -180,12 +188,6 @@ int waitsync_fd_to_close = -1; /* -w/--wait-sync */ #endif /* - * Initializing flag. All async routines watch this and only do their - * thing when it is clear. - */ -int initializing; - -/* * Version declaration */ extern const char *Version; @@ -238,6 +240,68 @@ static void library_unexpected_error(const char *, int, #endif /* !SIM */ +/* Bug2332 unearthed a problem in the interaction of reduced user + * privileges, the limits on memory usage and some versions of the + * pthread library on Linux systems. The 'pthread_cancel()' function and + * likely some others need to track the stack of the thread involved, + * and uses a function that comes from GCC (--> libgcc_s.so) to do + * this. Unfortunately the developers of glibc decided to load the + * library on demand, which speeds up program start but can cause + * trouble here: Due to all the things NTPD does to limit its resource + * usage, this deferred load of libgcc_s does not always work once the + * restrictions are in effect. + * + * One way out of this was attempting a forced link against libgcc_s + * when possible because it makes the library available immediately + * without deferred load. (The symbol resolution would still be dynamic + * and on demand, but the code would already be in the process image.) + * + * This is a tricky thing to do, since it's not necessary everywhere, + * not possible everywhere, has shown to break the build of other + * programs in the NTP suite and is now generally frowned upon. + * + * So we take a different approach here: We creat a worker thread that does + * actually nothing except waiting for cancellation and cancel it. If + * this is done before all the limitations are put in place, the + * machinery is pre-heated and all the runtime stuff should be in place + * and useable when needed. + * + * This uses only the standard pthread API and should work with all + * implementations of pthreads. It is not necessary everywhere, but it's + * cheap enough to go on nearly unnoticed. + */ +#ifdef NEED_PTHREAD_WARMUP + +/* simple thread function: sleep until cancelled, just to exercise + * thread cancellation. + */ +static void* +my_pthread_warmup_worker( + void *thread_args) +{ + (void)thread_args; + for (;;) + sleep(10); + return NULL; +} + +/* pre-heat threading: create a thread and cancel it, just to exercise + * thread cancellation. + */ +static void +my_pthread_warmup(void) +{ + pthread_t thread; + int rc; + rc = pthread_create( + &thread, NULL, my_pthread_warmup_worker, NULL); + if (0 == rc) { + pthread_cancel(thread); + pthread_join(thread, NULL); + } +} + +#endif /*defined(NEED_PTHREAD_WARMUP)*/ void @@ -451,6 +515,10 @@ ntpdmain( int zero; # endif +# ifdef NEED_PTHREAD_WARMUP + my_pthread_warmup(); +# endif + # ifdef HAVE_UMASK uv = umask(0); if (uv) @@ -791,13 +859,16 @@ ntpdmain( */ getconfig(argc, argv); - if (do_memlock) { + if (-1 == cur_memlock) { # if defined(HAVE_MLOCKALL) /* * lock the process into memory */ - if (!HAVE_OPT(SAVECONFIGQUIT) && - 0 != mlockall(MCL_CURRENT|MCL_FUTURE)) + if ( !HAVE_OPT(SAVECONFIGQUIT) +# ifdef RLIMIT_MEMLOCK + && -1 != DFLT_RLIMIT_MEMLOCK +# endif + && 0 != mlockall(MCL_CURRENT|MCL_FUTURE)) msyslog(LOG_ERR, "mlockall(): %m"); # else /* !HAVE_MLOCKALL follows */ # ifdef HAVE_PLOCK @@ -937,10 +1008,17 @@ getgroup: msyslog(LOG_ERR, "Cannot setegid() to group `%s': %m", group); exit (-1); } - if (group) - setgroups(1, &sw_gid); - else - initgroups(pw->pw_name, pw->pw_gid); + if (group) { + if (0 != setgroups(1, &sw_gid)) { + msyslog(LOG_ERR, "setgroups(1, %d) failed: %m", sw_gid); + exit (-1); + } + } + else if (pw) + if (0 != initgroups(pw->pw_name, pw->pw_gid)) { + msyslog(LOG_ERR, "initgroups(<%s>, %d) filed: %m", pw->pw_name, pw->pw_gid); + exit (-1); + } if (user && setuid(sw_uid)) { msyslog(LOG_ERR, "Cannot setuid() to user `%s': %m", user); exit (-1); |
