diff mbox series

iproute2: ip maddress: Check multiaddr length

Message ID 20200814084626.22953-1-s.hauer@pengutronix.de
State New
Headers show
Series iproute2: ip maddress: Check multiaddr length | expand

Commit Message

Sascha Hauer Aug. 14, 2020, 8:46 a.m. UTC 
ip maddress add|del takes a MAC address as argument, so insist on
getting a length of ETH_ALEN bytes. This makes sure the passed argument
is actually a MAC address and especially not an IPv4 address which
was previously accepted and silently taken as a MAC address.

While at it, do not print *argv in the error path as this has been
modified by ll_addr_a2n() and doesn't contain the full string anymore,
which can lead to misleading error messages.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 ip/ipmaddr.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
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Patch

diff --git a/ip/ipmaddr.c b/ip/ipmaddr.c
index 3400e055..9979ed58 100644
--- a/ip/ipmaddr.c
+++ b/ip/ipmaddr.c
@@ -291,7 +291,7 @@  static int multiaddr_modify(int cmd, int argc, char **argv)
 {
 	struct ifreq ifr = {};
 	int family;
-	int fd;
+	int fd, len;
 
 	if (cmd == RTM_NEWADDR)
 		cmd = SIOCADDMULTI;
@@ -313,9 +313,12 @@  static int multiaddr_modify(int cmd, int argc, char **argv)
 				usage();
 			if (ifr.ifr_hwaddr.sa_data[0])
 				duparg("address", *argv);
-			if (ll_addr_a2n(ifr.ifr_hwaddr.sa_data,
-					14, *argv) < 0) {
-				fprintf(stderr, "Error: \"%s\" is not a legal ll address.\n", *argv);
+			len = ll_addr_a2n(ifr.ifr_hwaddr.sa_data, 14, *argv);
+			if (len < 0)
+				exit(1);
+
+			if (len != ETH_ALEN) {
+				fprintf(stderr, "Error: Invalid address length %d - must be %d bytes\n", len, ETH_ALEN);
 				exit(1);
 			}
 		}