Y2038: query systemd-logind instead of utmp for username and tty (#2088)

configure.ac

@@ -2491,6 +2491,7 @@ AS_IF([test "x$with_systemd" != xno], [
     [*:yes],
        AC_DEFINE([HAVE_LIBSYSTEMD], [1], [Define if libsystemd is available])
        AC_DEFINE([USE_SYSTEMD], [1], [Define if systemd support is wanted ])
+       AC_CHECK_DECLS([sd_session_get_username], [], [], [#include <systemd/sd-login.h>])
   )
 ])
 AM_CONDITIONAL([HAVE_SYSTEMD], [test "x$have_systemd" = xyes])

meson.build

@@ -311,6 +311,11 @@ lib_systemd = dependency(
   required : get_option('systemd'))
 conf.set('HAVE_LIBSYSTEMD', lib_systemd.found() ? 1 : false)
 
+have = cc.has_function(
+  'sd_session_get_username',
+  dependencies : lib_systemd)
+conf.set('HAVE_DECL_SD_SESSION_GET_USERNAME', have ? 1 : false)
+
 lib_udev = dependency(
   'libudev',
   required : get_option('systemd'))
@@ -2316,7 +2321,7 @@ exe = executable(
   agetty_sources,
   include_directories : includes,
   link_with : [lib_common, logindefs_c],
-  dependencies : BSD ? lib_util : [],
+  dependencies : [BSD ? lib_util : [], lib_systemd],
   install_dir : sbindir,
   install : opt,
   build_by_default : opt)
@@ -2362,6 +2367,7 @@ exe = executable(
   wall_sources,
   include_directories : includes,
   link_with : [lib_common],
+  dependencies : [lib_systemd],
   install_dir : usrbin_exec_dir,
   install : opt,
   build_by_default : opt)
@@ -2380,6 +2386,7 @@ exe = executable(
   write_sources,
   include_directories : includes,
   link_with : [lib_common],
+  dependencies : [lib_systemd],
   install_dir : usrbin_exec_dir,
   install : opt,
   build_by_default : opt)

term-utils/Makemodule.am

@@ -58,6 +58,10 @@ endif
 if HAVE_ECONF
 agetty_LDADD += -leconf
 endif
+if HAVE_SYSTEMD
+agetty_LDADD += $(SYSTEMD_LIBS)
+agetty_CFLAGS = $(SYSTEMD_CFLAGS)
+endif
 endif # BUILD_AGETTY
 
 
@@ -98,6 +102,10 @@ dist_noinst_DATA += term-utils/wall.1.adoc
 wall_CFLAGS = $(SUID_CFLAGS) $(AM_CFLAGS)
 wall_LDFLAGS = $(SUID_LDFLAGS) $(AM_LDFLAGS)
 wall_LDADD = $(LDADD) libcommon.la
+if HAVE_SYSTEMD
+wall_LDADD += $(SYSTEMD_LIBS)
+wall_CFLAGS += $(SYSTEMD_CFLAGS)
+endif
 if USE_TTY_GROUP
 if MAKEINSTALL_DO_CHOWN
 install-exec-hook-wall::
@@ -118,6 +126,10 @@ write_SOURCES = term-utils/write.c
 write_CFLAGS = $(SUID_CFLAGS) $(AM_CFLAGS)
 write_LDFLAGS = $(SUID_LDFLAGS) $(AM_LDFLAGS)
 write_LDADD = $(LDADD) libcommon.la
+if HAVE_SYSTEMD
+write_LDADD += $(SYSTEMD_LIBS)
+write_CFLAGS += $(SYSTEMD_CFLAGS)
+endif
 
 if USE_TTY_GROUP
 if MAKEINSTALL_DO_CHOWN

term-utils/agetty.c

@@ -73,6 +73,11 @@
 # endif
 #endif
 
+#ifdef USE_SYSTEMD
+# include <systemd/sd-daemon.h>
+# include <systemd/sd-login.h>
+#endif
+
 #ifdef __linux__
 #  include <sys/kd.h>
 #  define USE_SYSLOG
@@ -2864,12 +2869,23 @@ static void output_special_char(struct issue *ie,
 	case 'U':
 	{
 		int users = 0;
-		struct utmpx *ut;
-		setutxent();
-		while ((ut = getutxent()))
-			if (ut->ut_type == USER_PROCESS)
-				users++;
-		endutxent();
+#ifdef USE_SYSTEMD
+		if (sd_booted() > 0) {
+			users = sd_get_sessions(NULL);
+			if (users < 0)
+				users = 0;
+		} else {
+#endif
+			users = 0;
+			struct utmpx *ut;
+			setutxent();
+			while ((ut = getutxent()))
+				if (ut->ut_type == USER_PROCESS)
+					users++;
+			endutxent();
+#ifdef USE_SYSTEMD
+		}
+#endif
 		if (c == 'U')
 			fprintf(ie->output, P_("%d user", "%d users", users), users);
 		else

term-utils/wall.c

@@ -61,6 +61,11 @@
 #include <sys/types.h>
 #include <grp.h>
 
+#if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
+# include <systemd/sd-login.h>
+# include <systemd/sd-daemon.h>
+#endif
+
 #include "nls.h"
 #include "xalloc.h"
 #include "strutils.h"
@@ -246,6 +251,37 @@ int main(int argc, char **argv)
 
 	iov.iov_base = mbuf;
 	iov.iov_len = mbufsize;
+#if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
+	if (sd_booted() > 0) {
+		char **sessions_list;
+		int sessions;
+
+		sessions = sd_get_sessions(&sessions_list);
+		if (sessions < 0)
+			errx(EXIT_FAILURE, _("error getting sessions: %s"),
+	             		strerror(-sessions));
+
+		for (int i = 0; i < sessions; i++) {
+			char *name, *tty;
+			int r;
+
+			if ((r = sd_session_get_username(sessions_list[i], &name)) < 0)
+				errx(EXIT_FAILURE, _("get user name failed: %s"), strerror (-r));
+
+			if (!(group_buf && !is_gr_member(name, group_buf))) {
+				if (sd_session_get_tty(sessions_list[i], &tty) >= 0) {
+					if ((p = ttymsg(&iov, 1, tty, timeout)) != NULL)
+						warnx("%s", p);
+
+					free(tty);
+				}
+			}
+			free(name);
+			free(sessions_list[i]);
+		}
+		free(sessions_list);
+	} else {
+#endif
 	while((utmpptr = getutxent())) {
 		if (!utmpptr->ut_user[0])
 			continue;
@@ -269,6 +305,9 @@ int main(int argc, char **argv)
 			warnx("%s", p);
 	}
 	endutxent();
+#if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
+	}
+#endif
 	free(mbuf);
 	free_group_workspace(group_buf);
 	exit(EXIT_SUCCESS);

term-utils/write.c

@@ -59,6 +59,11 @@
 #include <unistd.h>
 #include <utmpx.h>
 
+#if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
+# include <systemd/sd-login.h>
+# include <systemd/sd-daemon.h>
+#endif
+
 #include "c.h"
 #include "carefulputc.h"
 #include "closestream.h"
@@ -131,19 +136,56 @@ static int check_utmp(const struct write_control *ctl)
 {
 	struct utmpx *u;
 	int res = 1;
-
-	utmpxname(_PATH_UTMP);
-	setutxent();
-
-	while ((u = getutxent())) {
-		if (strncmp(ctl->dst_login, u->ut_user, sizeof(u->ut_user)) == 0 &&
-		    strncmp(ctl->dst_tty_name, u->ut_line, sizeof(u->ut_line)) == 0) {
-			res = 0;
-			break;
+#if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
+	if (sd_booted() > 0) {
+		char **sessions_list;
+		int sessions = sd_get_sessions(&sessions_list);
+		if (sessions < 0)
+			errx(EXIT_FAILURE, _("error getting sessions: %s"),
+				strerror(-sessions));
+
+		for (int i = 0; i < sessions; i++) {
+
+			char *name, *tty;
+			int r;
+
+			if ((r = sd_session_get_username(sessions_list[i], &name)) < 0)
+				errx(EXIT_FAILURE, _("get user name failed: %s"), strerror (-r));
+			if (sd_session_get_tty(sessions_list[i], &tty) < 0) {
+				free(name);
+				continue;
+			}
+
+			if  (strcmp(ctl->dst_login, name) == 0 &&
+					strcmp(ctl->dst_tty_name, tty) == 0) {
+				free(name);
+				free(tty);
+				res = 0;
+				break;
+			}
+			free(name);
+			free(tty);
+		}
+		for (int i = 0; i < sessions; i++)
+			free(sessions_list[i]);
+		free(sessions_list);
+	} else {
+#endif
+		utmpxname(_PATH_UTMP);
+		setutxent();
+
+		while ((u = getutxent())) {
+			if (strncmp(ctl->dst_login, u->ut_user, sizeof(u->ut_user)) == 0 &&
+		    		strncmp(ctl->dst_tty_name, u->ut_line, sizeof(u->ut_line)) == 0) {
+				res = 0;
+				break;
+			}
 		}
-	}
 
-	endutxent();
+		endutxent();
+#if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
+	}
+#endif
 	return res;
 }
 
@@ -163,6 +205,69 @@ static void search_utmp(struct write_control *ctl)
 	struct utmpx *u;
 	time_t best_atime = 0, tty_atime;
 	int num_ttys = 0, valid_ttys = 0, tty_writeable = 0, user_is_me = 0;
+
+#if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
+	if (sd_booted() > 0) {
+		char path[256];
+		char **sessions_list;
+		int sessions = sd_get_sessions(&sessions_list);
+		if (sessions < 0)
+			errx(EXIT_FAILURE, _("error getting sessions: %s"),
+			     strerror(-sessions));
+
+		for (int i = 0; i < sessions; i++) {
+			char *name, *tty;
+			int r;
+
+			if ((r = sd_session_get_username(sessions_list[i], &name)) < 0)
+				errx(EXIT_FAILURE, _("get user name failed: %s"), strerror (-r));
+
+			if  (strcmp(ctl->dst_login, name) != 0) {
+				free(name);
+				continue;
+			}
+
+			if (sd_session_get_tty(sessions_list[i], &tty) < 0) {
+				free(name);
+				continue;
+			}
+
+			num_ttys++;
+			snprintf(path, sizeof(path), "/dev/%s", tty);
+			if (check_tty(path, &tty_writeable, &tty_atime, 0)) {
+				/* bad term? skip */
+				free(name);
+				free(tty);
+				continue;
+			}
+			if (ctl->src_uid && !tty_writeable) {
+				/* skip ttys with msgs off */
+				free(name);
+				free(tty);
+				continue;
+			}
+			if (strcmp(tty, ctl->src_tty_name) == 0) {
+				user_is_me = 1;
+				free(name);
+				free(tty);
+				/* don't write to yourself */
+				continue;
+			}
+			valid_ttys++;
+			if (best_atime < tty_atime) {
+				best_atime = tty_atime;
+				free(ctl->dst_tty_path);
+				ctl->dst_tty_path = xstrdup(path);
+				ctl->dst_tty_name = ctl->dst_tty_path + 5;
+			}
+			free(name);
+			free(tty);
+		}
+		for (int i = 0; i < sessions; i++)
+			free(sessions_list[i]);
+		free(sessions_list);
+	} else {
+#endif
 	char path[sizeof(u->ut_line) + 6];
 
 	utmpxname(_PATH_UTMP);
@@ -197,6 +302,9 @@ static void search_utmp(struct write_control *ctl)
 	}
 
 	endutxent();
+#if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
+	}
+#endif
 	if (num_ttys == 0)
 		errx(EXIT_FAILURE, _("%s is not logged in"), ctl->dst_login);
 	if (valid_ttys == 0) {