From: Jakub Sitnicki <jakub@cloudflare.com>
Date: Sun, 31 May 2020 10:28:35 +0200
Subject: flow_dissector: Pull locking up from prog attach callback
Patch-mainline: v5.8-rc1
Git-commit: 171526f6fee84de0c39e2b7aa7e666ba0bbfd173
References: bsc#1176447
Split out the part of attach callback that happens with attach/detach lock
acquired. This structures the prog attach callback in a way that opens up
doors for moving the locking out of flow_dissector and into generic
callbacks for attaching/detaching progs to netns in subsequent patches.
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20200531082846.2117903-2-jakub@cloudflare.com
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
net/core/flow_dissector.c | 40 ++++++++++++++++++++--------------------
1 file changed, 20 insertions(+), 20 deletions(-)
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -109,15 +109,10 @@ int skb_flow_dissector_prog_query(const
return 0;
}
-int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
- struct bpf_prog *prog)
+static int flow_dissector_bpf_prog_attach(struct net *net,
+ struct bpf_prog *prog)
{
struct bpf_prog *attached;
- struct net *net;
- int ret = 0;
-
- net = current->nsproxy->net_ns;
- mutex_lock(&flow_dissector_mutex);
if (net == &init_net) {
/* BPF flow dissector in the root namespace overrides
@@ -130,33 +125,38 @@ int skb_flow_dissector_bpf_prog_attach(c
for_each_net(ns) {
if (ns == &init_net)
continue;
- if (rcu_access_pointer(ns->flow_dissector_prog)) {
- ret = -EEXIST;
- goto out;
- }
+ if (rcu_access_pointer(ns->flow_dissector_prog))
+ return -EEXIST;
}
} else {
/* Make sure root flow dissector is not attached
* when attaching to the non-root namespace.
*/
- if (rcu_access_pointer(init_net.flow_dissector_prog)) {
- ret = -EEXIST;
- goto out;
- }
+ if (rcu_access_pointer(init_net.flow_dissector_prog))
+ return -EEXIST;
}
attached = rcu_dereference_protected(net->flow_dissector_prog,
lockdep_is_held(&flow_dissector_mutex));
- if (attached == prog) {
+ if (attached == prog)
/* The same program cannot be attached twice */
- ret = -EINVAL;
- goto out;
- }
+ return -EINVAL;
+
rcu_assign_pointer(net->flow_dissector_prog, prog);
if (attached)
bpf_prog_put(attached);
-out:
+ return 0;
+}
+
+int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
+ struct bpf_prog *prog)
+{
+ int ret;
+
+ mutex_lock(&flow_dissector_mutex);
+ ret = flow_dissector_bpf_prog_attach(current->nsproxy->net_ns, prog);
mutex_unlock(&flow_dissector_mutex);
+
return ret;
}