Fix for the sshd(8) utmp problem. Previously, login(3) would ignore the tty

named by its argument and use ttyslot(3) instead to determine what slot to
use.  The problem is that sshd(8) calls pam_open_session(3) before forking
the child (as it should), at which point it does not have a controlling
terminal.  Also, ttyslot(3) is very crude as it assumes fd 0, 1 or 2 refers
to the controlling terminal, which is usually (but not always) the case.

Instead of using ttyslot(3) to determine the slot number, look up the
specified tty in /etc/ttys ourselves (this is what ttyslot(3) does anyway).

(perforce change 9969)

Sponsored by:	DARPA, NAI Labs

1 files changed, 9 insertions, 3 deletions

diff --git a/lib/libutil/login.c b/lib/libutil/login.c
index cbb6013..f54ce7b 100644
--- a/lib/libutil/login.c
+++ b/lib/libutil/login.c
@@ -44,19 +44,25 @@ static char sccsid[] = "@(#)login.c	8.1 (Berkeley) 6/4/93";
 #include <sys/types.h>
 
 #include <fcntl.h>
-#include <unistd.h>
+#include <libutil.h>
 #include <stdlib.h>
+#include <ttyent.h>
+#include <unistd.h>
 #include <utmp.h>
-#include <libutil.h>
 
 void
 login(ut)
 	struct utmp *ut;
 {
+	struct ttyent *ty;
 	int fd;
 	int tty;
 
-	tty = ttyslot();
+	setttyent();
+	for (tty = 1; (ty = getttyent()) != NULL; ++tty)
+		if (strcmp(ty->ty_name, ut->ut_line) == 0)
+			break;
+	endttyent();
 	if (tty > 0 && (fd = open(_PATH_UTMP, O_WRONLY|O_CREAT, 0644)) >= 0) {
 		(void)lseek(fd, (off_t)(tty * sizeof(struct utmp)), L_SET);
 		(void)write(fd, ut, sizeof(struct utmp));