[PATCH bpf-next v3 1/4] flow_dissector: Pull BPF program assignment up to bpf-netns
From: Jakub Sitnicki <jakub@cloudflare.com>
Date: 2020-06-25 14:14:13
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), networking [general], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Prepare for using bpf_prog_array to store attached programs by moving out code that updates the attached program out of flow dissector. Managing bpf_prog_array is more involved than updating a single bpf_prog pointer. This will let us do it all from one place, bpf/net_namespace.c, in the subsequent patch. No functional change intended. Acked-by: Andrii Nakryiko <redacted> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> --- include/net/flow_dissector.h | 3 ++- kernel/bpf/net_namespace.c | 20 ++++++++++++++++++-- net/core/flow_dissector.c | 13 ++----------- 3 files changed, 22 insertions(+), 14 deletions(-)
diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index a7eba43fe4e4..4b6e36288ddd 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h@@ -372,7 +372,8 @@ flow_dissector_init_keys(struct flow_dissector_key_control *key_control, } #ifdef CONFIG_BPF_SYSCALL -int flow_dissector_bpf_prog_attach(struct net *net, struct bpf_prog *prog); +int flow_dissector_bpf_prog_attach_check(struct net *net, + struct bpf_prog *prog); #endif /* CONFIG_BPF_SYSCALL */ #endif
diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c
index 78cf061f8179..b951dab2687f 100644
--- a/kernel/bpf/net_namespace.c
+++ b/kernel/bpf/net_namespace.c@@ -189,6 +189,7 @@ int netns_bpf_prog_query(const union bpf_attr *attr, int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog) { enum netns_bpf_attach_type type; + struct bpf_prog *attached; struct net *net; int ret;
@@ -207,12 +208,26 @@ int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog) switch (type) { case NETNS_BPF_FLOW_DISSECTOR: - ret = flow_dissector_bpf_prog_attach(net, prog); + ret = flow_dissector_bpf_prog_attach_check(net, prog); break; default: ret = -EINVAL; break; } + if (ret) + goto out_unlock; + + attached = rcu_dereference_protected(net->bpf.progs[type], + lockdep_is_held(&netns_bpf_mutex)); + if (attached == prog) { + /* The same program cannot be attached twice */ + ret = -EINVAL; + goto out_unlock; + } + rcu_assign_pointer(net->bpf.progs[type], prog); + if (attached) + bpf_prog_put(attached); + out_unlock: mutex_unlock(&netns_bpf_mutex);
@@ -277,7 +292,7 @@ static int netns_bpf_link_attach(struct net *net, struct bpf_link *link, switch (type) { case NETNS_BPF_FLOW_DISSECTOR: - err = flow_dissector_bpf_prog_attach(net, link->prog); + err = flow_dissector_bpf_prog_attach_check(net, link->prog); break; default: err = -EINVAL;
@@ -286,6 +301,7 @@ static int netns_bpf_link_attach(struct net *net, struct bpf_link *link, if (err) goto out_unlock; + rcu_assign_pointer(net->bpf.progs[type], link->prog); net->bpf.links[type] = link; out_unlock:
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index d02df0b6d0d9..b57fb1359395 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c@@ -70,10 +70,10 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector, EXPORT_SYMBOL(skb_flow_dissector_init); #ifdef CONFIG_BPF_SYSCALL -int flow_dissector_bpf_prog_attach(struct net *net, struct bpf_prog *prog) +int flow_dissector_bpf_prog_attach_check(struct net *net, + struct bpf_prog *prog) { enum netns_bpf_attach_type type = NETNS_BPF_FLOW_DISSECTOR; - struct bpf_prog *attached; if (net == &init_net) { /* BPF flow dissector in the root namespace overrides
@@ -97,15 +97,6 @@ int flow_dissector_bpf_prog_attach(struct net *net, struct bpf_prog *prog) return -EEXIST; } - attached = rcu_dereference_protected(net->bpf.progs[type], - lockdep_is_held(&netns_bpf_mutex)); - if (attached == prog) - /* The same program cannot be attached twice */ - return -EINVAL; - - rcu_assign_pointer(net->bpf.progs[type], prog); - if (attached) - bpf_prog_put(attached); return 0; } #endif /* CONFIG_BPF_SYSCALL */
--
2.25.4