From 2459b4c635858094df78abb9ca87d99f89fe8ca5 Mon Sep 17 00:00:00 2001 From: Nicolas Dichtel Date: Wed, 11 Oct 2017 16:24:48 +0200 Subject: net: enable interface alias removal via rtnl IFLA_IFALIAS is defined as NLA_STRING. It means that the minimal length of the attribute is 1 ("\0"). However, to remove an alias, the attribute length must be 0 (see dev_set_alias()). Let's define the type to NLA_BINARY to allow 0-length string, so that the alias can be removed. Example: $ ip l s dummy0 alias foo $ ip l l dev dummy0 5: dummy0: mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 link/ether ae:20:30:4f:a7:f3 brd ff:ff:ff:ff:ff:ff alias foo Before the patch: $ ip l s dummy0 alias "" RTNETLINK answers: Numerical result out of range After the patch: $ ip l s dummy0 alias "" $ ip l l dev dummy0 5: dummy0: mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 link/ether ae:20:30:4f:a7:f3 brd ff:ff:ff:ff:ff:ff CC: Oliver Hartkopp CC: Stephen Hemminger Fixes: 96ca4a2cc145 ("net: remove ifalias on empty given alias") Reported-by: Julien FLoret Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller --- net/core/rtnetlink.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index a6bcf86ce471..5ace48926b19 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1483,7 +1483,10 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = { [IFLA_LINKINFO] = { .type = NLA_NESTED }, [IFLA_NET_NS_PID] = { .type = NLA_U32 }, [IFLA_NET_NS_FD] = { .type = NLA_U32 }, - [IFLA_IFALIAS] = { .type = NLA_STRING, .len = IFALIASZ-1 }, + /* IFLA_IFALIAS is a string, but policy is set to NLA_BINARY to + * allow 0-length string (needed to remove an alias). + */ + [IFLA_IFALIAS] = { .type = NLA_BINARY, .len = IFALIASZ - 1 }, [IFLA_VFINFO_LIST] = {. type = NLA_NESTED }, [IFLA_VF_PORTS] = { .type = NLA_NESTED }, [IFLA_PORT_SELF] = { .type = NLA_NESTED }, -- cgit v1.2.3-59-g8ed1b