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authorMartin KaFai Lau <kafai@fb.com>2019-03-12 10:23:04 -0700
committerAlexei Starovoitov <ast@kernel.org>2019-03-13 12:04:35 -0700
commitdbafd7ddd62369b2f3926ab847cbf8fc40e800b7 (patch)
tree35ce32dfc258798b98bb4d7e4253f34bb4cf43e1 /net
parentbpf: Fix bpf_tcp_sock and bpf_sk_fullsock issue related to bpf_sk_release (diff)
downloadlinux-dev-dbafd7ddd62369b2f3926ab847cbf8fc40e800b7.tar.xz
linux-dev-dbafd7ddd62369b2f3926ab847cbf8fc40e800b7.zip
bpf: Add bpf_get_listener_sock(struct bpf_sock *sk) helper
Add a new helper "struct bpf_sock *bpf_get_listener_sock(struct bpf_sock *sk)" which returns a bpf_sock in TCP_LISTEN state. It will trace back to the listener sk from a request_sock if possible. It returns NULL for all other cases. No reference is taken because the helper ensures the sk is in SOCK_RCU_FREE (where the TCP_LISTEN sock should be in). Hence, bpf_sk_release() is unnecessary and the verifier does not allow bpf_sk_release(listen_sk) to be called either. The following is also allowed because the bpf_prog is run under rcu_read_lock(): sk = bpf_sk_lookup_tcp(); /* if (!sk) { ... } */ listen_sk = bpf_get_listener_sock(sk); /* if (!listen_sk) { ... } */ bpf_sk_release(sk); src_port = listen_sk->src_port; /* Allowed */ Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/core/filter.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index 36b6afacf83c..647c63a7b25b 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5418,6 +5418,23 @@ static const struct bpf_func_proto bpf_tcp_sock_proto = {
.arg1_type = ARG_PTR_TO_SOCK_COMMON,
};
+BPF_CALL_1(bpf_get_listener_sock, struct sock *, sk)
+{
+ sk = sk_to_full_sk(sk);
+
+ if (sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_RCU_FREE))
+ return (unsigned long)sk;
+
+ return (unsigned long)NULL;
+}
+
+static const struct bpf_func_proto bpf_get_listener_sock_proto = {
+ .func = bpf_get_listener_sock,
+ .gpl_only = false,
+ .ret_type = RET_PTR_TO_SOCKET_OR_NULL,
+ .arg1_type = ARG_PTR_TO_SOCK_COMMON,
+};
+
BPF_CALL_1(bpf_skb_ecn_set_ce, struct sk_buff *, skb)
{
unsigned int iphdr_len;
@@ -5603,6 +5620,8 @@ cg_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
#ifdef CONFIG_INET
case BPF_FUNC_tcp_sock:
return &bpf_tcp_sock_proto;
+ case BPF_FUNC_get_listener_sock:
+ return &bpf_get_listener_sock_proto;
case BPF_FUNC_skb_ecn_set_ce:
return &bpf_skb_ecn_set_ce_proto;
#endif
@@ -5698,6 +5717,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_sk_release_proto;
case BPF_FUNC_tcp_sock:
return &bpf_tcp_sock_proto;
+ case BPF_FUNC_get_listener_sock:
+ return &bpf_get_listener_sock_proto;
#endif
default:
return bpf_base_func_proto(func_id);