[PATCH v3] net: allow IFLA_INET_CONF messages when NLA_F_NESTED unset

[Quentin Armitage <quentin@armitage.org.uk>]

Commit fa8fca88714c ("ipv4: validate IPV4_DEVCONF attributes properly")
added validation of IFLA_INET_CONF attributes, and in the process
changed the call of nla_for_each_nested() to nla_parse_nested(). A
side effect of this change is that the IFLA_INET_CONF option is now
tested for NLA_F_NESTED being set, and fails if it is not. Prior to the
commit there was no check of NLA_F_NESTED.

Change nla_parse_nested() to nla_parse(). This restores the previous
functionality of not checking NLA_F_NESTED, thereby allowing code that
(incorrectly) doesn't set NLA_F_NESTED to continue to work.

This issue was identified because keepalived started logging errors when
it was configuring macvlans that it created.

Fixes: fa8fca88714c ("ipv4: validate IPV4_DEVCONF attributes properly")

Signed-off-by: Quentin Armitage <quentin@armitage.org.uk>
---
 net/ipv4/devinet.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index a90be57c63be..5b6b11c943e4 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2117,9 +2117,10 @@ static int inet_validate_link_af(const struct net_device *dev,
 		return err;
 
 	if (tb[IFLA_INET_CONF]) {
-		err = nla_parse_nested(nested_tb, IPV4_DEVCONF_MAX,
-				       tb[IFLA_INET_CONF], inet_devconf_policy,
-				       extack);
+		err = nla_parse(nested_tb, IPV4_DEVCONF_MAX,
+				nla_data(tb[IFLA_INET_CONF]),
+				nla_len(tb[IFLA_INET_CONF]),
+				inet_devconf_policy, extack);
 
 		if (err < 0)
 			return err;
-- 
2.55.0