Date: Sun, 26 Jan 2014 22:50:01 GMT From: dfilter@FreeBSD.ORG (dfilter service) To: freebsd-bugs@FreeBSD.org Subject: Re: misc/183495: commit references a PR Message-ID: <201401262250.s0QMo1Sl019433@freefall.freebsd.org>
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The following reply was made to PR misc/183495; it has been noted by GNATS. From: dfilter@FreeBSD.ORG (dfilter service) To: bug-followup@FreeBSD.org Cc: Subject: Re: misc/183495: commit references a PR Date: Sun, 26 Jan 2014 22:49:33 +0000 (UTC) Author: jilles Date: Sun Jan 26 22:49:24 2014 New Revision: 261193 URL: http://svnweb.freebsd.org/changeset/base/261193 Log: login: Clean up PAM and audit, then exit, on SIGHUP and SIGTERM. This avoids leaving stale entries in utmpx after the connection is closed on an open login session. It also allows a clean way (SIGTERM) to forcibly terminate a user's terminal session. This does not affect the situation for "hung" processes after the connection is closed. The foreground process group receives SIGHUP and the tty becomes inaccessible. Also replace all use of the obsolete signal() function with sigaction() (not only the part where it is actually required: SIGHUP and SIGTERM must mask the other as well when caught). PR: misc/183495 Reviewed by: ed Modified: head/usr.bin/login/login.c Modified: head/usr.bin/login/login.c ============================================================================== --- head/usr.bin/login/login.c Sun Jan 26 21:19:33 2014 (r261192) +++ head/usr.bin/login/login.c Sun Jan 26 22:49:24 2014 (r261193) @@ -83,6 +83,7 @@ __FBSDID("$FreeBSD$"); static int auth_pam(void); static void bail(int, int); +static void bail_internal(int, int, int); static int export(const char *); static void export_pam_environment(void); static int motd(const char *); @@ -94,6 +95,7 @@ static void refused(const char *, cons static const char *stypeof(char *); static void sigint(int); static void timedout(int); +static void bail_sig(int); static void usage(void); #define TTYGRPNAME "tty" /* group to own ttys */ @@ -172,13 +174,18 @@ main(int argc, char *argv[]) login_cap_t *lc = NULL; login_cap_t *lc_user = NULL; pid_t pid; + sigset_t mask, omask; + struct sigaction sa; #ifdef USE_BSM_AUDIT char auditsuccess = 1; #endif - (void)signal(SIGQUIT, SIG_IGN); - (void)signal(SIGINT, SIG_IGN); - (void)signal(SIGHUP, SIG_IGN); + sa.sa_flags = SA_RESTART; + (void)sigfillset(&sa.sa_mask); + sa.sa_handler = SIG_IGN; + (void)sigaction(SIGQUIT, &sa, NULL); + (void)sigaction(SIGINT, &sa, NULL); + (void)sigaction(SIGHUP, &sa, NULL); if (setjmp(timeout_buf)) { if (failures) badlogin(username); @@ -186,7 +193,8 @@ main(int argc, char *argv[]) timeout); bail(NO_SLEEP_EXIT, 0); } - (void)signal(SIGALRM, timedout); + sa.sa_handler = timedout; + (void)sigaction(SIGALRM, &sa, NULL); (void)alarm(timeout); (void)setpriority(PRIO_PROCESS, 0, 0); @@ -370,7 +378,14 @@ main(int argc, char *argv[]) /* committed to login -- turn off timeout */ (void)alarm((u_int)0); - (void)signal(SIGHUP, SIG_DFL); + + (void)sigemptyset(&mask); + (void)sigaddset(&mask, SIGHUP); + (void)sigaddset(&mask, SIGTERM); + (void)sigprocmask(SIG_BLOCK, &mask, &omask); + sa.sa_handler = bail_sig; + (void)sigaction(SIGHUP, &sa, NULL); + (void)sigaction(SIGTERM, &sa, NULL); endpwent(); @@ -550,10 +565,17 @@ main(int argc, char *argv[]) /* * Parent: wait for child to finish, then clean up * session. + * + * If we get SIGHUP or SIGTERM, clean up the session + * and exit right away. This will make the terminal + * inaccessible and send SIGHUP to the foreground + * process group. */ int status; setproctitle("-%s [pam]", getprogname()); + (void)sigprocmask(SIG_SETMASK, &omask, NULL); waitpid(pid, &status, 0); + (void)sigprocmask(SIG_BLOCK, &mask, NULL); bail(NO_SLEEP_EXIT, 0); } @@ -627,10 +649,15 @@ main(int argc, char *argv[]) login_close(lc_user); login_close(lc); - (void)signal(SIGALRM, SIG_DFL); - (void)signal(SIGQUIT, SIG_DFL); - (void)signal(SIGINT, SIG_DFL); - (void)signal(SIGTSTP, SIG_IGN); + sa.sa_handler = SIG_DFL; + (void)sigaction(SIGALRM, &sa, NULL); + (void)sigaction(SIGQUIT, &sa, NULL); + (void)sigaction(SIGINT, &sa, NULL); + (void)sigaction(SIGTERM, &sa, NULL); + (void)sigaction(SIGHUP, &sa, NULL); + sa.sa_handler = SIG_IGN; + (void)sigaction(SIGTSTP, &sa, NULL); + (void)sigprocmask(SIG_SETMASK, &omask, NULL); /* * Login shells have a leading '-' in front of argv[0] @@ -847,17 +874,20 @@ sigint(int signo __unused) static int motd(const char *motdfile) { - sig_t oldint; + struct sigaction newint, oldint; FILE *f; int ch; if ((f = fopen(motdfile, "r")) == NULL) return (-1); motdinterrupt = 0; - oldint = signal(SIGINT, sigint); + newint.sa_handler = sigint; + newint.sa_flags = 0; + sigfillset(&newint.sa_mask); + sigaction(SIGINT, &newint, &oldint); while ((ch = fgetc(f)) != EOF && !motdinterrupt) putchar(ch); - signal(SIGINT, oldint); + sigaction(SIGINT, &oldint, NULL); if (ch != EOF || ferror(f)) { fclose(f); return (-1); @@ -966,12 +996,10 @@ pam_cleanup(void) } } -/* - * Exit, optionally after sleeping a few seconds - */ -void -bail(int sec, int eval) +static void +bail_internal(int sec, int eval, int signo) { + struct sigaction sa; pam_cleanup(); #ifdef USE_BSM_AUDIT @@ -979,5 +1007,36 @@ bail(int sec, int eval) audit_logout(); #endif (void)sleep(sec); - exit(eval); + if (signo == 0) + exit(eval); + else { + sa.sa_handler = SIG_DFL; + sa.sa_flags = 0; + (void)sigemptyset(&sa.sa_mask); + (void)sigaction(signo, &sa, NULL); + (void)sigaddset(&sa.sa_mask, signo); + (void)sigprocmask(SIG_UNBLOCK, &sa.sa_mask, NULL); + raise(signo); + exit(128 + signo); + } +} + +/* + * Exit, optionally after sleeping a few seconds + */ +static void +bail(int sec, int eval) +{ + bail_internal(sec, eval, 0); +} + +/* + * Exit because of a signal. + * This is not async-signal safe, so only call async-signal safe functions + * while the signal is unmasked. + */ +static void +bail_sig(int signo) +{ + bail_internal(NO_SLEEP_EXIT, 0, signo); } _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscribe@freebsd.org"
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