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3a41611bc

Denys Vlasenko

2010-04-05

FAILED Duration: 29s

Subject

telnetd: write LOGIN/DEAD_PROCESS utmp records. Closes bug 1363

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

include/libbb.h +4 -2 init/halt.c +8 -7 libbb/utmp.c +86 -37 loginutils/getty.c +5 -3 loginutils/login.c +1 -1 miscutils/last.c +2 -1 networking/telnetd.c +28 -5

include/libbb.h+4 -2

@@ -797,9 +797,11 @@ void die_if_bad_username(const char* name) FAST_FUNC;
	#endif

	#if ENABLE_FEATURE_UTMP
-	void FAST_FUNC update_utmp(int new_type, const char short_tty, const char username, const char *opt_host);
+	void FAST_FUNC write_new_utmp(pid_t pid, int new_type, const char tty_name, const char username, const char *hostname);
+	void FAST_FUNC update_utmp(pid_t pid, int new_type, const char tty_name, const char username, const char *hostname);
	#else
-	# define update_utmp(new_type, short_tty, username, opt_host) ((void)0)
+	# define write_new_utmp(pid, new_type, tty_name, username, hostname) ((void)0)
+	# define update_utmp(pid, new_type, tty_name, username, hostname) ((void)0)
	#endif

	int execable_file(const char *name) FAST_FUNC;

init/halt.c+8 -7

@@ -18,17 +18,18 @@ static void write_wtmp(void)
	{
	struct utmp utmp;
	struct utsname uts;
-	if (access(bb_path_wtmp_file, R_OK\|W_OK) == -1) {
+	/* "man utmp" says wtmp file should not be created automagically */
+	/*if (access(bb_path_wtmp_file, R_OK\|W_OK) == -1) {
	close(creat(bb_path_wtmp_file, 0664));
-	}
+	}*/
	memset(&utmp, 0, sizeof(utmp));
	utmp.ut_tv.tv_sec = time(NULL);
-	safe_strncpy(utmp.ut_user, "shutdown", UT_NAMESIZE);
+	strcpy(utmp.ut_user, "shutdown"); /* it is wide enough */
	utmp.ut_type = RUN_LVL;
-	safe_strncpy(utmp.ut_id, "~~", sizeof(utmp.ut_id));
-	safe_strncpy(utmp.ut_line, "~~", UT_LINESIZE);
-	if (uname(&uts) == 0)
-	safe_strncpy(utmp.ut_host, uts.release, sizeof(utmp.ut_host));
+	utmp.ut_id[0] = '~'; utmp.ut_id[1] = '~'; /* = strcpy(utmp.ut_id, "~~"); */
+	utmp.ut_line[0] = '~'; utmp.ut_line[1] = '~'; /* = strcpy(utmp.ut_line, "~~"); */
+	uname(&uts);
+	safe_strncpy(utmp.ut_host, uts.release, sizeof(utmp.ut_host));
	updwtmp(bb_path_wtmp_file, &utmp);
	}
	#else

libbb/utmp.c+86 -37

@@ -15,37 +15,87 @@ static void touch(const char *filename)
	close(open(filename, O_WRONLY \| O_CREAT, 0664));
	}

+	// TODO: move to libbb
+	static const char* skip_dev_pfx(const char *tty_name)
+	{
+	if (strncmp(tty_name, "/dev/", 5) == 0)
+	tty_name += 5;
+	return tty_name;
+	}
+
+	void FAST_FUNC write_new_utmp(pid_t pid, int new_type, const char tty_name, const char username, const char *hostname)
+	{
+	struct utmp utent;
+	char *id;
+	unsigned width;
+
+	memset(&utent, 0, sizeof(utent));
+	utent.ut_pid = pid;
+	utent.ut_type = new_type;
+	tty_name = skip_dev_pfx(tty_name);
+	safe_strncpy(utent.ut_line, tty_name, sizeof(utent.ut_line));
+	if (username)
+	safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
+	if (hostname)
+	safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
+	utent.ut_tv.tv_sec = time(NULL);
+
+	/* Invent our own ut_id. ut_id is only 4 chars wide.
+	* Try to fit something remotely meaningful... */
+	id = utent.ut_id;
+	width = sizeof(utent.ut_id);
+	if (tty_name[0] == 'p') {
+	/* if "ptyXXX", map to "pXXX" */
+	/* if "pts/XX", map to "p/XX" */
+	*id++ = 'p';
+	width--;
+	} /* else: usually it's "ttyXXXX", map to "XXXX" */
+	if (strlen(tty_name) > 3)
+	tty_name += 3;
+	strncpy(id, tty_name, width);
+
+	touch(_PATH_UTMP);
+	//utmpname(_PATH_UTMP);
+	setutent();
+	/* Append new one (hopefully, unless we collide on ut_id) */
+	pututline(&utent);
+	endutent();
+
+	#if ENABLE_FEATURE_WTMP
+	/* "man utmp" says wtmp file should not be created automagically */
+	/touch(bb_path_wtmp_file);/
+	updwtmp(bb_path_wtmp_file, &utent);
+	#endif
+	}
+
	/*
	* Read "man utmp" to make sense out of it.
	*/
-	void FAST_FUNC update_utmp(int new_type, const char short_tty, const char username, const char *opt_host)
+	void FAST_FUNC update_utmp(pid_t pid, int new_type, const char tty_name, const char username, const char *hostname)
	{
	struct utmp utent;
-	struct utmp *ut;
-	pid_t pid;
+	struct utmp *utp;

	touch(_PATH_UTMP);
-	utmpname(_PATH_UTMP);
+	//utmpname(_PATH_UTMP);
	setutent();

-	pid = getpid();
	/* Did init/getty/telnetd/sshd/... create an entry for us?
	* It should be (new_type-1), but we'd also reuse
	* any other potentially stale xxx_PROCESS entry */
-	while ((ut = getutent()) != NULL) {
-	if (ut->ut_pid == pid
+	while ((utp = getutent()) != NULL) {
+	if (utp->ut_pid == pid
	// && ut->ut_line[0]
-	&& ut->ut_id[0] /* must have nonzero id */
-	&& ( ut->ut_type == INIT_PROCESS
-	\|\| ut->ut_type == LOGIN_PROCESS
-	\|\| ut->ut_type == USER_PROCESS
-	\|\| ut->ut_type == DEAD_PROCESS
+	&& utp->ut_id[0] /* must have nonzero id */
+	&& ( utp->ut_type == INIT_PROCESS
+	\|\| utp->ut_type == LOGIN_PROCESS
+	\|\| utp->ut_type == USER_PROCESS
+	\|\| utp->ut_type == DEAD_PROCESS
	)
	) {
-	utent = ut; / struct copy */
-	if (ut->ut_type >= new_type) {
+	if (utp->ut_type >= new_type) {
	/* Stale record. Nuke hostname */
-	memset(utent.ut_host, 0, sizeof(utent.ut_host));
+	memset(utp->ut_host, 0, sizeof(utp->ut_host));
	}
	/* NB: pututline (see later) searches for matching utent
	* using getutid(utent) - we must not change ut_id
@@ -54,39 +104,38 @@ void FAST_FUNC update_utmp(int new_type, const char short_tty, const char user
	break;
	}
	}
-	endutent();
+	//endutent(); - no need, pututline can deal with (and actually likes)
+	//the situation when utmp file is positioned on found record

-	if (!ut) {
-	/* Didn't find anything, create new one */
-	memset(&utent, 0, sizeof(utent));
-	utent.ut_pid = pid;
-	/* Invent our own ut_id. ut_id is only 4 chars wide.
-	* Try to fit something remotely meaningful... */
-	if (short_tty[0] == 'p') {
-	/* if "ptyXXX", map to "pXXX" */
-	/* if "pts/XX", map to "p/XX" */
-	utent.ut_id[0] = 'p';
-	strncpy(utent.ut_id + 1, short_tty + 3, sizeof(utent.ut_id)-1);
-	} else {
-	/* assuming it's "ttyXXXX", map to "XXXX" */
-	strncpy(utent.ut_id, short_tty + 3, sizeof(utent.ut_id));
-	}
+	if (!utp) {
+	if (new_type != DEAD_PROCESS)
+	write_new_utmp(pid, new_type, tty_name, username, hostname);
+	else
+	endutent();
+	return;
	}

+	/* Make a copy. We can't use *utp, pututline's internal getutid
+	* will overwrite it before it is used! */
+	utent = *utp;
+
	utent.ut_type = new_type;
-	safe_strncpy(utent.ut_line, short_tty, sizeof(utent.ut_line));
-	safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
-	if (opt_host)
-	safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
+	if (tty_name)
+	safe_strncpy(utent.ut_line, skip_dev_pfx(tty_name), sizeof(utent.ut_line));
+	if (username)
+	safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
+	if (hostname)
+	safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
	utent.ut_tv.tv_sec = time(NULL);

	/* Update, or append new one */
-	setutent();
+	//setutent();
	pututline(&utent);
	endutent();

	#if ENABLE_FEATURE_WTMP
-	touch(bb_path_wtmp_file);
+	/* "man utmp" says wtmp file should not be created automagically */
+	/touch(bb_path_wtmp_file);/
	updwtmp(bb_path_wtmp_file, &utent);
	#endif
	}

loginutils/getty.c+5 -3

@@ -19,7 +19,7 @@
	#include <syslog.h>

	#if ENABLE_FEATURE_UTMP
-	#include <utmp.h> /* LOGIN_PROCESS */
+	# include <utmp.h> /* LOGIN_PROCESS */
	#endif

	#ifndef IUCLC
@@ -579,6 +579,7 @@ int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
	int getty_main(int argc UNUSED_PARAM, char **argv)
	{
	int n;
+	pid_t pid;
	char fakehost = NULL; / Fake hostname for ut_host */
	char logname; / login name, given to /bin/login */
	/* Merging these into "struct local" may _seem_ to reduce
@@ -651,17 +652,18 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
	/* tcgetattr() + error check */
	ioctl_or_perror_and_die(0, TCGETS, &termios, "%s: TCGETS", options.tty);

+	pid = getpid();
	#ifdef __linux__
	// FIXME: do we need this? Otherwise "-" case seems to be broken...
	// /* Forcibly make fd 0 our controlling tty, even if another session
	// * has it as a ctty. (Another session loses ctty). */
	// ioctl(0, TIOCSCTTY, (void*)1);
	/* Make ourself a foreground process group within our session */
-	tcsetpgrp(0, getpid());
+	tcsetpgrp(0, pid);
	#endif

	/* Update the utmp file. This tty is ours now! */
-	update_utmp(LOGIN_PROCESS, options.tty, "LOGIN", fakehost);
+	update_utmp(pid, LOGIN_PROCESS, options.tty, "LOGIN", fakehost);

	/* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */
	debug("calling termios_init\n");

loginutils/login.c+1 -1

@@ -384,7 +384,7 @@ int login_main(int argc UNUSED_PARAM, char **argv)
	fchown(0, pw->pw_uid, pw->pw_gid);
	fchmod(0, 0600);

-	update_utmp(USER_PROCESS, short_tty, username, run_by_root ? opt_host : NULL);
+	update_utmp(getpid(), USER_PROCESS, short_tty, username, run_by_root ? opt_host : NULL);

	/* We trust environment only if we run by root */
	if (ENABLE_LOGIN_SCRIPTS && run_by_root)

miscutils/last.c+2 -1

@@ -92,7 +92,8 @@ int last_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
	goto next;
	}
	if (ut.ut_type != DEAD_PROCESS
-	&& ut.ut_user[0] && ut.ut_line[0]
+	&& ut.ut_user[0]
+	&& ut.ut_line[0]
	) {
	ut.ut_type = USER_PROCESS;
	}

networking/telnetd.c+28 -5

@@ -20,18 +20,22 @@
	* Vladimir Oleynik <[email protected]> 2001
	* Set process group corrections, initial busybox port
	*/
-
	#define DEBUG 0

	#include "libbb.h"
	#include <syslog.h>

	#if DEBUG
-	#define TELCMDS
-	#define TELOPTS
+	# define TELCMDS
+	# define TELOPTS
	#endif
	#include <arpa/telnet.h>

+	#if ENABLE_FEATURE_UTMP
+	# include <utmp.h> /* LOGIN_PROCESS */
+	#endif
+
+
	struct tsession {
	struct tsession *next;
	pid_t shell_pid;
@@ -319,7 +323,11 @@ make_new_session(
	xopen(tty_name, O_RDWR); /* becomes our ctty */
	xdup2(0, 1);
	xdup2(0, 2);
-	tcsetpgrp(0, getpid()); /* switch this tty's process group to us */
+	pid = getpid();
+	tcsetpgrp(0, pid); /* switch this tty's process group to us */
+
+	//TODO: fetch remote addr via getpeername (see ftpd.c)
+	write_new_utmp(pid, LOGIN_PROCESS, tty_name, /username:/ "LOGIN", /hostname:/ NULL);

	/* The pseudo-terminal allocated to the client is configured to operate
	* in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */
@@ -358,12 +366,13 @@ make_new_session(
	static void
	free_session(struct tsession *ts)
	{
-	struct tsession *t = G.sessions;
+	struct tsession *t;

	if (option_mask32 & OPT_INETD)
	exit(EXIT_SUCCESS);

	/* Unlink this telnet session from the session list */
+	t = G.sessions;
	if (t == ts)
	G.sessions = ts->next;
	else {
@@ -414,6 +423,7 @@ static void handle_sigchld(int sig UNUSED_PARAM)
	{
	pid_t pid;
	struct tsession *ts;
+	int save_errno = errno;

	/* Looping: more than one child may have exited */
	while (1) {
@@ -424,11 +434,22 @@ static void handle_sigchld(int sig UNUSED_PARAM)
	while (ts) {
	if (ts->shell_pid == pid) {
	ts->shell_pid = -1;
+	// man utmp:
+	// When init(8) finds that a process has exited, it locates its utmp entry
+	// by ut_pid, sets ut_type to DEAD_PROCESS, and clears ut_user, ut_host
+	// and ut_time with null bytes.
+	// [same applies to other processes which maintain utmp entries, like telnetd]
+	//
+	// We do not bother actually clearing fields:
+	// it might be interesting to know who was logged in and from where
+	update_utmp(pid, DEAD_PROCESS, /tty_name:/ NULL, /username:/ NULL, /hostname:/ NULL);
	break;
	}
	ts = ts->next;
	}
	}
+
+	errno = save_errno;
	}

	int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@@ -689,6 +710,8 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
	ts = next;
	continue;
	kill_session:
+	if (ts->shell_pid > 0)
+	update_utmp(ts->shell_pid, DEAD_PROCESS, /tty_name:/ NULL, /username:/ NULL, /hostname:/ NULL);
	free_session(ts);
	ts = next;
	}