From da790aa6c6bc2f3e6f64713626bf709c35f7f83d Mon Sep 17 00:00:00 2001
From: Florian Forster <octo@leeloo.lan.home.verplant.org>
Date: Tue, 29 Sep 2009 17:44:05 +0200
Subject: [PATCH] =?utf8?q?oping:=20Disable=20the=20=E2=80=9C-f=E2=80=9D=20?=
 =?utf8?q?option=20when=20real=20and=20effective=20user=20IDs=20don't=20ma?=
 =?utf8?q?tch.?=
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Thanks to Steve Kemp who reported this issue as Debian bug #548684.
<http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=548684>
---
 src/mans/oping.pod |  4 ++++
 src/oping.c        | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/src/mans/oping.pod b/src/mans/oping.pod
index 8a3cb58..fc8911d 100644
--- a/src/mans/oping.pod
+++ b/src/mans/oping.pod
@@ -58,6 +58,10 @@ Set the outgoing network device to use.
 Instead of specifying hostnames on the command line, read them from
 I<filename>. If I<filename> is B<->, read from C<STDIN>.
 
+This option is only available if the real user ID (as returned by L<getuid(2)>)
+and the effective user ID (as returned by L<geteuid(2)>) match. This is meant
+to avoid security issues when I<oping> is installed with the SUID-bit.
+
 =back
 
 =head1 SEE ALSO
diff --git a/src/oping.c b/src/oping.c
index fc4cb5f..8419710 100644
--- a/src/oping.c
+++ b/src/oping.c
@@ -27,6 +27,7 @@
 # include <string.h>
 # include <errno.h>
 # include <assert.h>
+# include <unistd.h>
 #else
 # error "You don't have the standard C99 header files installed"
 #endif /* STDC_HEADERS */
@@ -133,6 +134,11 @@ static void usage_exit (const char *name, int status)
 	exit (status);
 }
 
+static _Bool is_setuid (void)
+{
+	return (getuid () != geteuid ());
+}
+
 static int read_options (int argc, char **argv)
 {
 	int optchar;
@@ -164,6 +170,13 @@ static int read_options (int argc, char **argv)
 				break;
 
 			case 'f':
+				if (is_setuid ())
+				{
+					fprintf (stderr, "For security reasons the `-f' option "
+							"is disabled if real and effective "
+							"user IDs don't match. Sorry.\n");
+				}
+				else
 				{
 					if (opt_filename != NULL)
 						free (opt_filename);
-- 
2.30.2