do not set IPv6-only options on IPv4 addresses

'home', 'nodad' and 'mngtmpaddr' options are IPv6-only, but it is possible to set them on IPv4 addresses, too. This should not be possible.

Fix this adding a check on the protocol family before setting the flags, and exiting with invarg() on error.

Andrea Claudi (3):
ip address: do not set nodad option for IPv4 addresses ip address: do not set home option for IPv4 addresses ip address: do not set mngtmpaddr option for IPv4 addresses

 ip/ipaddress.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

2.20.1

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: <BROADCAST,NOARP> 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.

---
 ip/ipaddress.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

index 47e5be7462fe7..38356cc929e7b 100644
@@ -2250,7 +2250,10 @@ 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
+				invarg("nodad option can be set only for IPv6 addresses\n", *argv);
 		} else if (strcmp(*argv, "mngtmpaddr") == 0) {
 			ifa_flags |= IFA_F_MANAGETEMPADDR;
 		} else if (strcmp(*argv, "noprefixroute") == 0) {

2.20.1

'mngtmpaddr' option make the kernel manage temporary addresses created from the specified one as template on behalf of Privacy Extensions (RFC3041). This option should be available only for IPv6 addresses, as correctly stated in the manpage.

However it is possible to set mngtmpaddr on IPv4 addresses, too:

$ ip link add dummy0 type dummy
$ ip -4 addr add 192.168.1.1 dev dummy0 mngtmpaddr
$ ip a
1: dummy0: <BROADCAST,NOARP> 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 mngtmpaddr dummy0
      valid_lft forever preferred_lft forever

Fix this adding a check on the protocol family before setting IFA_F_MANAGETEMPADDR flag.

---
 ip/ipaddress.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

index 0f59e0a40468c..06a9f904201c0 100644
@@ -2258,7 +2258,10 @@ static int ipaddr_modify(int cmd, int flags, int argc, char **argv)
 			else
 				invarg("nodad option can be set only for IPv6 addresses\n", *argv);
 		} else if (strcmp(*argv, "mngtmpaddr") == 0) {
-			ifa_flags |= IFA_F_MANAGETEMPADDR;
+			if (req.ifa.ifa_family == AF_INET6)
+				ifa_flags |= IFA_F_MANAGETEMPADDR;
+			else
+				invarg("mngtmpaddr option can be set only for IPv6 addresses\n", *argv);
 		} else if (strcmp(*argv, "noprefixroute") == 0) {
 			ifa_flags |= IFA_F_NOPREFIXROUTE;
 		} else if (strcmp(*argv, "autojoin") == 0) {

2.20.1

'home' option designates a IPv6 address as "home address" as defined in RFC 6275. This option should be available only for IPv6 addresses, as correctly stated in the manpage.

However it is possible to set home on IPv4 addresses, too:

$ ip link add dummy0 type dummy
$ ip -4 addr add 192.168.1.1 dev dummy0 home
$ ip a
1: dummy0: <BROADCAST,NOARP> 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 home dummy0
      valid_lft forever preferred_lft forever

Fix this adding a check on the protocol family before setting IFA_F_HOMEADDRESS flag.

---
 ip/ipaddress.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

index 38356cc929e7b..0f59e0a40468c 100644
@@ -2248,7 +2248,10 @@ static int ipaddr_modify(int cmd, int flags, int argc, char **argv)
 			if (set_lifetime(&preferred_lft, *argv))
 				invarg("preferred_lft value", *argv);
 		} else if (strcmp(*argv, "home") == 0) {
-			ifa_flags |= IFA_F_HOMEADDRESS;
+			if (req.ifa.ifa_family == AF_INET6)
+				ifa_flags |= IFA_F_HOMEADDRESS;
+			else
+				invarg("home option can be set only for IPv6 addresses\n", *argv);
 		} else if (strcmp(*argv, "nodad") == 0) {
 			if (req.ifa.ifa_family == AF_INET6)
 				ifa_flags |= IFA_F_NODAD;

2.20.1

Maybe this should be a warning, not a failure.
A little concerned that there will be some user with a scripted setup that this breaks.

Hi Stephen,
I think that if a script wrongly uses some of these flags on a IPv4 address, it most probably operates on an unexpected address, since everyone is aware that these flags are IPv6 only. In other words we are breaking a scripted setup that is already broken.
In this case it's probably worth exiting with error and give the author the chance to fix the script, otherwise the error can go unnoticed.

If you prefer, I can send a v2 with warnings instead of errors, just let me know.

Regards,
Andrea

Recent changes for strict mode have shown people do interesting things with scripts and like the silent "ignores". :-(