1 files changed, 91 insertions, 0 deletions

diff --git a/usr.sbin/sendmail/test/t_exclopen.c b/usr.sbin/sendmail/test/t_exclopen.c
new file mode 100644
index 000000000000..54f7873f4b33
--- /dev/null
+++ b/usr.sbin/sendmail/test/t_exclopen.c
@@ -0,0 +1,91 @@
+/*
+**  This program tests your system to see if you have the lovely
+**  security-defeating semantics that an open with O_CREAT|O_EXCL
+**  set will successfully open a file named by a symbolic link that
+**  points to a non-existent file.  Sadly, Posix is mute on what
+**  should happen in this situation.
+**
+**  Results to date:
+**	AIX 3.2		OK
+**	BSD family	OK
+**	  BSD/OS 2.1	OK
+**	  FreeBSD 2.1	OK
+**	DEC OSF/1 3.0	OK
+**	HP-UX 9.04	FAIL
+**	HP-UX 9.05	FAIL
+**	HP-UX 9.07	OK
+**	HP-UX 10.01	OK
+**	HP-UX 10.10	OK
+**	HP-UX 10.20	OK
+**	Irix 5.3	OK
+**	Irix 6.2	OK
+**	Linux		OK
+**	NeXT 2.1	OK
+**	Solaris 2.x	OK
+**	SunOS 4.x	OK
+**	Ultrix 4.3	OK
+*/
+
+#include <stdio.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+char Attacker[128];
+char Attackee[128];
+
+main(argc, argv)
+	int argc;
+	char **argv;
+{
+	struct stat st;
+
+	sprintf(Attacker, "/tmp/attacker.%d.%ld", getpid(), time(NULL));
+	sprintf(Attackee, "/tmp/attackee.%d.%ld", getpid(), time(NULL));
+
+	if (symlink(Attackee, Attacker) < 0)
+	{
+		printf("Could not create %s->%s symlink: %d\n",
+			Attacker, Attackee, errno);
+		bail(1);
+	}
+	(void) unlink(Attackee);
+	if (stat(Attackee, &st) >= 0)
+	{
+		printf("%s already exists -- remove and try again.\n",
+			Attackee);
+		bail(1);
+	}
+	if (open(Attacker, O_WRONLY|O_CREAT|O_EXCL, 0644) < 0)
+	{
+		int saveerr = errno;
+
+		if (stat(Attackee, &st) >= 0)
+		{
+			printf("Weird.  Open failed but %s was created anyhow (errno = %d)\n",
+				Attackee, saveerr);
+			bail(1);
+		}
+		printf("Good show!  Exclusive open works properly with symbolic links (errno = %d).\n",
+			saveerr);
+		bail(0);
+	}
+	if (stat(Attackee, &st) < 0)
+	{
+		printf("Weird.  Open succeeded but %s was not created\n",
+			Attackee);
+		bail(2);
+	}
+	printf("Bad news: you can do an exclusive open through a symbolic link\n");
+	printf("\tBe sure you #define BOGUS_O_EXCL in conf.h\n");
+	bail(1);
+}
+
+bail(stat)
+	int stat;
+{
+	(void) unlink(Attacker);
+	(void) unlink(Attackee);
+	exit(stat);
+}