From 22e6c58b8c2843337ec4e8464b1ce6e869ca5bf4 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Mon, 15 Oct 2018 18:56:41 -0700 Subject: [PATCH] netlink: Add answer_flags to netlink_callback With dump filtering we need a way to ensure the NLM_F_DUMP_FILTERED flag is set on a message back to the user if the data returned is influenced by some input attributes. Normally this can be done as messages are added to the skb, but if the filter results in no data being returned, the user could be confused as to why. This patch adds answer_flags to the netlink_callback allowing dump handlers to set the NLM_F_DUMP_FILTERED at a minimum in the NLMSG_DONE message ensuring the flag gets back to the user. The netlink_callback space is initialized to 0 via a memset in __netlink_dump_start, so init of the new answer_flags is covered. Signed-off-by: David Ahern Signed-off-by: David S. Miller --- include/linux/netlink.h | 1 + net/netlink/af_netlink.c | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/netlink.h b/include/linux/netlink.h index 72580f1a72a2..4da90a6ab536 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -180,6 +180,7 @@ struct netlink_callback { u16 family; u16 min_dump_alloc; bool strict_check; + u16 answer_flags; unsigned int prev_seq, seq; long args[6]; }; diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index e613a9f89600..6bb9f3cde0b0 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2257,7 +2257,8 @@ static int netlink_dump(struct sock *sk) } nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, - sizeof(nlk->dump_done_errno), NLM_F_MULTI); + sizeof(nlk->dump_done_errno), + NLM_F_MULTI | cb->answer_flags); if (WARN_ON(!nlh)) goto errout_skb; -- 2.30.2