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flow_dissector: Pull locking up from prog attach callback

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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
This commit is contained in:
Jakub Sitnicki 2020-05-31 10:28:35 +02:00 committed by Alexei Starovoitov
parent febeb6dff7
commit 171526f6fe
1 changed files with 20 additions and 20 deletions
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40
net/core/flow_dissector.c
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@ -109,15 +109,10 @@ int skb_flow_dissector_prog_query(const union bpf_attr *attr,
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(const union bpf_attr *attr,
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;
}