On Mon, Oct 01, 2018 at 05:28:27PM -0700, David Ahern wrote:
> From: David Ahern <dsah...@gmail.com>
>
> Pass extack to dump callbacks by adding extack to netlink_dump_control,
> transferring to netlink_callback and adding to the netlink_dump. Update
> rtnetlink as the first user. Update netlink_dump to add any message after
> the dump_done_errno.
>
> Signed-off-by: David Ahern <dsah...@gmail.com>
This makes sense to me as it would allow us to report back more
meaningful errors to userspace.
> ---
> include/linux/netlink.h | 2 ++
> net/core/rtnetlink.c | 1 +
> net/netlink/af_netlink.c | 20 +++++++++++++++-----
> 3 files changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/netlink.h b/include/linux/netlink.h
> index 71f121b66ca8..8fc90308a653 100644
> --- a/include/linux/netlink.h
> +++ b/include/linux/netlink.h
> @@ -176,6 +176,7 @@ struct netlink_callback {
> void *data;
> /* the module that dump function belong to */
> struct module *module;
> + struct netlink_ext_ack *extack;
> u16 family;
> u16 min_dump_alloc;
> unsigned int prev_seq, seq;
> @@ -197,6 +198,7 @@ struct netlink_dump_control {
> int (*done)(struct netlink_callback *);
> void *data;
> struct module *module;
> + struct netlink_ext_ack *extack;
> u16 min_dump_alloc;
> };
>
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index 35162e1b06ad..da91b38297d3 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -4689,6 +4689,7 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb,
> struct nlmsghdr *nlh,
> .dump = dumpit,
> .min_dump_alloc = min_dump_alloc,
> .module = owner,
> + .extack = extack
> };
> err = netlink_dump_start(rtnl, skb, nlh, &c);
> /* netlink_dump_start() will keep a reference on
> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> index e3a0538ec0be..7094156c94f0 100644
> --- a/net/netlink/af_netlink.c
> +++ b/net/netlink/af_netlink.c
> @@ -129,7 +129,7 @@ static const char *const
> nlk_cb_mutex_key_strings[MAX_LINKS + 1] = {
> "nlk_cb_mutex-MAX_LINKS"
> };
>
> -static int netlink_dump(struct sock *sk);
> +static int netlink_dump(struct sock *sk, struct netlink_ext_ack *extack);
>
> /* nl_table locking explained:
> * Lookup and traversal are protected with an RCU read-side lock. Insertion
> @@ -1981,7 +1981,7 @@ static int netlink_recvmsg(struct socket *sock, struct
> msghdr *msg, size_t len,
>
> if (nlk->cb_running &&
> atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
> - ret = netlink_dump(sk);
> + ret = netlink_dump(sk, NULL);
> if (ret) {
> sk->sk_err = -ret;
> sk->sk_error_report(sk);
> @@ -2168,7 +2168,7 @@ EXPORT_SYMBOL(__nlmsg_put);
> * It would be better to create kernel thread.
> */
>
> -static int netlink_dump(struct sock *sk)
> +static int netlink_dump(struct sock *sk, struct netlink_ext_ack *extack)
> {
> struct netlink_sock *nlk = nlk_sk(sk);
> struct netlink_callback *cb;
> @@ -2222,8 +2222,11 @@ 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 +2249,12 @@ static int netlink_dump(struct sock *sk)
> memcpy(nlmsg_data(nlh), &nlk->dump_done_errno,
> sizeof(nlk->dump_done_errno));
>
> + if (extack && 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
> @@ -2307,6 +2316,7 @@ int __netlink_dump_start(struct sock *ssk, struct
> sk_buff *skb,
> cb->module = control->module;
> cb->min_dump_alloc = control->min_dump_alloc;
> cb->skb = skb;
> + cb->extack = control->extack;
>
> if (control->start) {
> ret = control->start(cb);
> @@ -2319,7 +2329,7 @@ int __netlink_dump_start(struct sock *ssk, struct
> sk_buff *skb,
>
> mutex_unlock(nlk->cb_mutex);
>
> - ret = netlink_dump(sk);
> + ret = netlink_dump(sk, cb->extack);
>
> sock_put(sk);
>
> --
> 2.11.0
>
