From 8ae99cc46d7713069ee626a4ce4335aaeca9892f Mon Sep 17 00:00:00 2001 From: Andrea Claudi Date: Tue, 25 Jun 2019 12:29:55 +0200 Subject: [PATCH] ip address: do not set nodad option for IPv4 addresses Duplicate Address Detection (RFC 4862) is available only for IPv6 addresses. As a consequence, 'nodad' option, turning it off, should be available only for IPv6, and is defined like that in the man page. However it is possible to set nodad on IPv4 addresses, too: $ ip link add dummy0 type dummy $ ip -4 addr add 192.168.1.1 dev dummy0 nodad $ ip a 1: dummy0: mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether 1a:6d:c6:96:ca:f8 brd ff:ff:ff:ff:ff:ff inet 192.168.1.1/32 scope global nodad dummy0 valid_lft forever preferred_lft forever Fix this adding a check on the protocol family before setting IFA_F_NODAD flag. Fixes: bac735c53a36d ("enabled to manipulate the flags of IFA_F_HOMEADDRESS or IFA_F_NODAD from ip.") Signed-off-by: Andrea Claudi Signed-off-by: Stephen Hemminger --- ip/ipaddress.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/ip/ipaddress.c b/ip/ipaddress.c index fd79f978..1b8ab783 100644 --- a/ip/ipaddress.c +++ b/ip/ipaddress.c @@ -2249,7 +2249,10 @@ static int ipaddr_modify(int cmd, int flags, int argc, char **argv) } else if (strcmp(*argv, "home") == 0) { ifa_flags |= IFA_F_HOMEADDRESS; } else if (strcmp(*argv, "nodad") == 0) { - ifa_flags |= IFA_F_NODAD; + if (req.ifa.ifa_family == AF_INET6) + ifa_flags |= IFA_F_NODAD; + else + fprintf(stderr, "Warning: nodad option can be set only for IPv6 addresses\n"); } else if (strcmp(*argv, "mngtmpaddr") == 0) { ifa_flags |= IFA_F_MANAGETEMPADDR; } else if (strcmp(*argv, "noprefixroute") == 0) {