From 40a34121ac1dc52ed9cd34a8f4e48e32517a52fd Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Wed, 3 Nov 2021 13:47:32 -0700 Subject: [PATCH] bpf, sockmap: Use stricter sk state checks in sk_lookup_assign In order to fix an issue with sockets in TCP sockmap redirect cases we plan to allow CLOSE state sockets to exist in the sockmap. However, the check in bpf_sk_lookup_assign() currently only invalidates sockets in the TCP_ESTABLISHED case relying on the checks on sockmap insert to ensure we never SOCK_CLOSE state sockets in the map. To prepare for this change we flip the logic in bpf_sk_lookup_assign() to explicitly test for the accepted cases. Namely, a tcp socket in TCP_LISTEN or a udp socket in TCP_CLOSE state. This also makes the code more resilent to future changes. Suggested-by: Jakub Sitnicki Signed-off-by: John Fastabend Signed-off-by: Daniel Borkmann Reviewed-by: Jakub Sitnicki Link: https://lore.kernel.org/bpf/20211103204736.248403-2-john.fastabend@gmail.com --- include/linux/skmsg.h | 12 ++++++++++++ net/core/filter.c | 6 ++++-- net/core/sock_map.c | 6 ------ 3 files changed, 16 insertions(+), 8 deletions(-) diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h index b425684..584d94b 100644 --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -507,6 +507,18 @@ static inline bool sk_psock_strp_enabled(struct sk_psock *psock) return !!psock->saved_data_ready; } +static inline bool sk_is_tcp(const struct sock *sk) +{ + return sk->sk_type == SOCK_STREAM && + sk->sk_protocol == IPPROTO_TCP; +} + +static inline bool sk_is_udp(const struct sock *sk) +{ + return sk->sk_type == SOCK_DGRAM && + sk->sk_protocol == IPPROTO_UDP; +} + #if IS_ENABLED(CONFIG_NET_SOCK_MSG) #define BPF_F_STRPARSER (1UL << 1) diff --git a/net/core/filter.c b/net/core/filter.c index 8e8d3b4..a684182 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -10423,8 +10423,10 @@ BPF_CALL_3(bpf_sk_lookup_assign, struct bpf_sk_lookup_kern *, ctx, return -EINVAL; if (unlikely(sk && sk_is_refcounted(sk))) return -ESOCKTNOSUPPORT; /* reject non-RCU freed sockets */ - if (unlikely(sk && sk->sk_state == TCP_ESTABLISHED)) - return -ESOCKTNOSUPPORT; /* reject connected sockets */ + if (unlikely(sk && sk_is_tcp(sk) && sk->sk_state != TCP_LISTEN)) + return -ESOCKTNOSUPPORT; /* only accept TCP socket in LISTEN */ + if (unlikely(sk && sk_is_udp(sk) && sk->sk_state != TCP_CLOSE)) + return -ESOCKTNOSUPPORT; /* only accept UDP socket in CLOSE */ /* Check if socket is suitable for packet L3/L4 protocol */ if (sk && sk->sk_protocol != ctx->protocol) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index e252b8e..f39ef79 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -511,12 +511,6 @@ static bool sock_map_op_okay(const struct bpf_sock_ops_kern *ops) ops->op == BPF_SOCK_OPS_TCP_LISTEN_CB; } -static bool sk_is_tcp(const struct sock *sk) -{ - return sk->sk_type == SOCK_STREAM && - sk->sk_protocol == IPPROTO_TCP; -} - static bool sock_map_redirect_allowed(const struct sock *sk) { if (sk_is_tcp(sk)) -- 2.7.4