From d19da360ee0f3e6c1375391db1a724b66fd43312 Mon Sep 17 00:00:00 2001 From: Lorenz Bauer Date: Mon, 9 Mar 2020 11:12:34 +0000 Subject: [PATCH] bpf: tcp: Move assertions into tcp_bpf_get_proto We need to ensure that sk->sk_prot uses certain callbacks, so that code that directly calls e.g. tcp_sendmsg in certain corner cases works. To avoid spurious asserts, we must to do this only if sk_psock_update_proto has not yet been called. The same invariants apply for tcp_bpf_check_v6_needs_rebuild, so move the call as well. Doing so allows us to merge tcp_bpf_init and tcp_bpf_reinit. Signed-off-by: Lorenz Bauer Signed-off-by: Daniel Borkmann Reviewed-by: Jakub Sitnicki Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20200309111243.6982-4-lmb@cloudflare.com --- include/net/tcp.h | 1 - net/core/sock_map.c | 25 +++++++++---------------- net/ipv4/tcp_bpf.c | 42 ++++++++++++++++++++++-------------------- 3 files changed, 31 insertions(+), 37 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 07f947cc80e6..ccf39d80b695 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -2196,7 +2196,6 @@ struct sk_msg; struct sk_psock; int tcp_bpf_init(struct sock *sk); -void tcp_bpf_reinit(struct sock *sk); int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes, int flags); int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, diff --git a/net/core/sock_map.c b/net/core/sock_map.c index cb8f740f7949..fafcbd22ecba 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -145,8 +145,8 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs, struct sock *sk) { struct bpf_prog *msg_parser, *skb_parser, *skb_verdict; - bool skb_progs, sk_psock_is_new = false; struct sk_psock *psock; + bool skb_progs; int ret; skb_verdict = READ_ONCE(progs->skb_verdict); @@ -191,18 +191,14 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs, ret = -ENOMEM; goto out_progs; } - sk_psock_is_new = true; } if (msg_parser) psock_set_prog(&psock->progs.msg_parser, msg_parser); - if (sk_psock_is_new) { - ret = tcp_bpf_init(sk); - if (ret < 0) - goto out_drop; - } else { - tcp_bpf_reinit(sk); - } + + ret = tcp_bpf_init(sk); + if (ret < 0) + goto out_drop; write_lock_bh(&sk->sk_callback_lock); if (skb_progs && !psock->parser.enabled) { @@ -239,15 +235,12 @@ static int sock_map_link_no_progs(struct bpf_map *map, struct sock *sk) if (IS_ERR(psock)) return PTR_ERR(psock); - if (psock) { - tcp_bpf_reinit(sk); - return 0; + if (!psock) { + psock = sk_psock_init(sk, map->numa_node); + if (!psock) + return -ENOMEM; } - psock = sk_psock_init(sk, map->numa_node); - if (!psock) - return -ENOMEM; - ret = tcp_bpf_init(sk); if (ret < 0) sk_psock_put(sk, psock); diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 3327afa05c3d..ed8a8f3c9afe 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -629,14 +629,6 @@ static int __init tcp_bpf_v4_build_proto(void) } core_initcall(tcp_bpf_v4_build_proto); -static void tcp_bpf_update_sk_prot(struct sock *sk, struct sk_psock *psock) -{ - int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4; - int config = psock->progs.msg_parser ? TCP_BPF_TX : TCP_BPF_BASE; - - sk_psock_update_proto(sk, psock, &tcp_bpf_prots[family][config]); -} - static int tcp_bpf_assert_proto_ops(struct proto *ops) { /* In order to avoid retpoline, we make assumptions when we call @@ -648,34 +640,44 @@ static int tcp_bpf_assert_proto_ops(struct proto *ops) ops->sendpage == tcp_sendpage ? 0 : -ENOTSUPP; } -void tcp_bpf_reinit(struct sock *sk) +static struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock) { - struct sk_psock *psock; + int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4; + int config = psock->progs.msg_parser ? TCP_BPF_TX : TCP_BPF_BASE; - sock_owned_by_me(sk); + if (!psock->sk_proto) { + struct proto *ops = READ_ONCE(sk->sk_prot); - rcu_read_lock(); - psock = sk_psock(sk); - tcp_bpf_update_sk_prot(sk, psock); - rcu_read_unlock(); + if (tcp_bpf_assert_proto_ops(ops)) + return ERR_PTR(-EINVAL); + + tcp_bpf_check_v6_needs_rebuild(sk, ops); + } + + return &tcp_bpf_prots[family][config]; } int tcp_bpf_init(struct sock *sk) { - struct proto *ops = READ_ONCE(sk->sk_prot); struct sk_psock *psock; + struct proto *prot; sock_owned_by_me(sk); rcu_read_lock(); psock = sk_psock(sk); - if (unlikely(!psock || psock->sk_proto || - tcp_bpf_assert_proto_ops(ops))) { + if (unlikely(!psock)) { rcu_read_unlock(); return -EINVAL; } - tcp_bpf_check_v6_needs_rebuild(sk, ops); - tcp_bpf_update_sk_prot(sk, psock); + + prot = tcp_bpf_get_proto(sk, psock); + if (IS_ERR(prot)) { + rcu_read_unlock(); + return PTR_ERR(prot); + } + + sk_psock_update_proto(sk, psock, prot); rcu_read_unlock(); return 0; } -- 2.25.1