From 289247dab9e3af73d5c05bc50f6b1b58ec84216a Mon Sep 17 00:00:00 2001
From: Joachim Wiberg <troglobit@gmail.com>
Date: Sun, 7 Mar 2021 13:25:40 +0100
Subject: [PATCH] plugins: netlink: slightly stricter ifname validation

Check if ifname contains double periods, this should *not* be a valid
name, though eth0.10 is, et0..10 is not.  Should protect better against
directory traversal attacks.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
---
 plugins/netlink.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/plugins/netlink.c b/plugins/netlink.c
index 49984c52..370e0a30 100644
--- a/plugins/netlink.c
+++ b/plugins/netlink.c
@@ -120,6 +120,9 @@ static int validate_ifname(const char *ifname)
 	if (strlen(ifname) >= IFNAMSIZ)
 		return 1;
 
+	if (strstr(ifname, ".."))
+		return 1;
+
 	while (*ifname) {
 		if (*ifname == '/' || isspace(*ifname))
 			return 1;