Merge branch 'bpf: Add socket destroy capability'

Aditi Ghag says:

====================

This patch set adds the capability to destroy sockets in BPF. We plan to
use the capability in Cilium to force client sockets to reconnect when
their remote load-balancing backends are deleted. The other use case is
on-the-fly policy enforcement where existing socket connections
prevented by policies need to be terminated.

The use cases, and more details around
the selected approach were presented at LPC 2022 -
https://lpc.events/event/16/contributions/1358/.
RFC discussion -
https://lore.kernel.org/netdev/CABG=zsBEh-P4NXk23eBJw7eajB5YJeRS7oPXnTAzs=yob4EMoQ@mail.gmail.com/T/#u.
v8 patch series -
https://lore.kernel.org/bpf/20230517175359.527917-1-aditi.ghag@isovalent.com/

v9 highlights:
Address review comments:
Martin:
- Rearranged the kfunc filter patch, and added the missing break
  statement.
- Squashed the extended selftest/bpf patch.
Yonghong:
- Revised commit message for patch 1.

(Below notes are same as v8 patch series that are still relevant. Refer to
earlier patch series versions for other notes.)
- I hit a snag while writing the kfunc where verifier complained about the
  `sock_common` type passed from TCP iterator. With kfuncs, there don't
  seem to be any options available to pass BTF type hints to the verifier
  (equivalent of `ARG_PTR_TO_BTF_ID_SOCK_COMMON`, as was the case with the
  helper).  As a result, I changed the argument type of the sock_destory
  kfunc to `sock_common`.
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index db24ed8f8509..6c2a5f1c63c4 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2962,7 +2962,6 @@ static int bpf_iter_tcp_seq_show(struct seq_file *seq, void *v)
 	struct bpf_iter_meta meta;
 	struct bpf_prog *prog;
 	struct sock *sk = v;
-	bool slow;
 	uid_t uid;
 	int ret;
 
@@ -2970,7 +2969,7 @@ static int bpf_iter_tcp_seq_show(struct seq_file *seq, void *v)
 		return 0;
 
 	if (sk_fullsock(sk))
-		slow = lock_sock_fast(sk);
+		lock_sock(sk);
 
 	if (unlikely(sk_unhashed(sk))) {
 		ret = SEQ_SKIP;
@@ -2994,7 +2993,7 @@ static int bpf_iter_tcp_seq_show(struct seq_file *seq, void *v)
 
 unlock:
 	if (sk_fullsock(sk))
-		unlock_sock_fast(sk, slow);
+		release_sock(sk);
 	return ret;
 
 }
@@ -3356,7 +3355,7 @@ static struct bpf_iter_reg tcp_reg_info = {
 	.ctx_arg_info_size	= 1,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__tcp, sk_common),
-		  PTR_TO_BTF_ID_OR_NULL },
+		  PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
 	},
 	.get_func_proto		= bpf_iter_tcp_get_func_proto,
 	.seq_info		= &tcp_seq_info,