[PATCH v2 3/7] net/tap: check interface name in kvargs

[Stephen Hemminger <stephen@networkplumber.org>]

If interface name is passed to remote or iface then check
the length and for invalid characters. This avoids problems where
name gets truncated or rejected by kernel.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by Keith Wiles <keith.wiles@intel.com>
---
 drivers/net/tap/rte_eth_tap.c | 38 +++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index 11e402e42bd0..d8e9ede7ac7c 100644
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -37,6 +37,7 @@
 #include <linux/if_tun.h>
 #include <linux/if_ether.h>
 #include <fcntl.h>
+#include <ctype.h>
 
 #include <tap_rss.h>
 #include <rte_eth_tap.h>
@@ -1884,6 +1885,24 @@ eth_dev_tap_create(struct rte_vdev_device *vdev, char *tap_name,
 	return -EINVAL;
 }
 
+/* make sure name is a possible Linux network device name */
+static bool
+is_valid_iface(const char *name)
+{
+	if (*name == '\0')
+		return false;
+
+	if (strnlen(name, IFNAMSIZ) == IFNAMSIZ)
+		return false;
+
+	while (*name) {
+		if (*name == '/' || *name == ':' || isspace(*name))
+			return false;
+		name++;
+	}
+	return true;
+}
+
 static int
 set_interface_name(const char *key __rte_unused,
 		   const char *value,
@@ -1891,12 +1910,17 @@ set_interface_name(const char *key __rte_unused,
 {
 	char *name = (char *)extra_args;
 
-	if (value)
+	if (value) {
+		if (!is_valid_iface(value)) {
+			TAP_LOG(ERR, "TAP invalid remote interface name (%s)",
+				value);
+			return -1;
+		}
 		strlcpy(name, value, RTE_ETH_NAME_MAX_LEN);
-	else
+	} else {
 		snprintf(name, RTE_ETH_NAME_MAX_LEN, "%s%d",
 			 DEFAULT_TAP_NAME, tap_unit - 1);
-
+	}
 	return 0;
 }
 
@@ -1907,8 +1931,14 @@ set_remote_iface(const char *key __rte_unused,
 {
 	char *name = (char *)extra_args;
 
-	if (value)
+	if (value) {
+		if (!is_valid_iface(value)) {
+			TAP_LOG(ERR, "TAP invalid remote interface name (%s)",
+				value);
+			return -1;
+		}
 		strlcpy(name, value, RTE_ETH_NAME_MAX_LEN);
+	}
 
 	return 0;
 }
-- 
2.20.1