netlink: Pass extack to dump handlers
Declare extack in netlink_dump and pass to dump handlers via
netlink_callback. Add any extack message after the dump_done_errno
allowing error messages to be returned. This will be useful when
strict checking is done on dump requests, returning why the dump
fails EINVAL.
Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Christian Brauner <christian@brauner.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index e3a0538..7ac585f 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2171,6 +2171,7 @@ EXPORT_SYMBOL(__nlmsg_put);
static int netlink_dump(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
+ struct netlink_ext_ack extack = {};
struct netlink_callback *cb;
struct sk_buff *skb = NULL;
struct nlmsghdr *nlh;
@@ -2222,8 +2223,11 @@ static int netlink_dump(struct sock *sk)
skb_reserve(skb, skb_tailroom(skb) - alloc_size);
netlink_skb_set_owner_r(skb, sk);
- if (nlk->dump_done_errno > 0)
+ if (nlk->dump_done_errno > 0) {
+ cb->extack = &extack;
nlk->dump_done_errno = cb->dump(skb, cb);
+ cb->extack = NULL;
+ }
if (nlk->dump_done_errno > 0 ||
skb_tailroom(skb) < nlmsg_total_size(sizeof(nlk->dump_done_errno))) {
@@ -2246,6 +2250,12 @@ static int netlink_dump(struct sock *sk)
memcpy(nlmsg_data(nlh), &nlk->dump_done_errno,
sizeof(nlk->dump_done_errno));
+ if (extack._msg && nlk->flags & NETLINK_F_EXT_ACK) {
+ nlh->nlmsg_flags |= NLM_F_ACK_TLVS;
+ if (!nla_put_string(skb, NLMSGERR_ATTR_MSG, extack._msg))
+ nlmsg_end(skb, nlh);
+ }
+
if (sk_filter(sk, skb))
kfree_skb(skb);
else