From 273b7f0fb44847c41814a59901977be284daa447 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Thu, 1 Sep 2022 17:29:18 -0700 Subject: [PATCH] bpf: Change bpf_getsockopt(SOL_TCP) to reuse do_tcp_getsockopt() This patch changes bpf_getsockopt(SOL_TCP) to reuse do_tcp_getsockopt(). It removes the duplicated code from bpf_getsockopt(SOL_TCP). Before this patch, there were some optnames available to bpf_setsockopt(SOL_TCP) but missing in bpf_getsockopt(SOL_TCP). For example, TCP_NODELAY, TCP_MAXSEG, TCP_KEEPIDLE, TCP_KEEPINTVL, and a few more. It surprises users from time to time. This patch automatically closes this gap without duplicating more code. bpf_getsockopt(TCP_SAVED_SYN) does not free the saved_syn, so it stays in sol_tcp_sockopt(). For string name value like TCP_CONGESTION, bpf expects it is always null terminated, so sol_tcp_sockopt() decrements optlen by one before calling do_tcp_getsockopt() and the 'if (optlen < saved_optlen) memset(..,0,..);' in __bpf_getsockopt() will always do a null termination. Signed-off-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20220902002918.2894511-1-kafai@fb.com Signed-off-by: Alexei Starovoitov --- include/net/tcp.h | 2 ++ net/core/filter.c | 74 +++++++++++++++++++++++++++-------------------- net/ipv4/tcp.c | 4 +-- 3 files changed, 47 insertions(+), 33 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index c03a50c72f40..735e957f7f4b 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -402,6 +402,8 @@ void tcp_init_sock(struct sock *sk); void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb); __poll_t tcp_poll(struct file *file, struct socket *sock, struct poll_table_struct *wait); +int do_tcp_getsockopt(struct sock *sk, int level, + int optname, sockptr_t optval, sockptr_t optlen); int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval, int __user *optlen); bool tcp_bpf_bypass_getsockopt(int level, int optname); diff --git a/net/core/filter.c b/net/core/filter.c index 9b26653a7e1f..beadd5b83e6c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5100,8 +5100,9 @@ static int bpf_sol_tcp_setsockopt(struct sock *sk, int optname, return 0; } -static int sol_tcp_setsockopt(struct sock *sk, int optname, - char *optval, int optlen) +static int sol_tcp_sockopt(struct sock *sk, int optname, + char *optval, int *optlen, + bool getopt) { if (sk->sk_prot->setsockopt != tcp_setsockopt) return -EINVAL; @@ -5118,17 +5119,51 @@ static int sol_tcp_setsockopt(struct sock *sk, int optname, case TCP_USER_TIMEOUT: case TCP_NOTSENT_LOWAT: case TCP_SAVE_SYN: - if (optlen != sizeof(int)) + if (*optlen != sizeof(int)) return -EINVAL; break; case TCP_CONGESTION: + if (*optlen < 2) + return -EINVAL; + break; + case TCP_SAVED_SYN: + if (*optlen < 1) + return -EINVAL; break; default: - return bpf_sol_tcp_setsockopt(sk, optname, optval, optlen); + if (getopt) + return -EINVAL; + return bpf_sol_tcp_setsockopt(sk, optname, optval, *optlen); + } + + if (getopt) { + if (optname == TCP_SAVED_SYN) { + struct tcp_sock *tp = tcp_sk(sk); + + if (!tp->saved_syn || + *optlen > tcp_saved_syn_len(tp->saved_syn)) + return -EINVAL; + memcpy(optval, tp->saved_syn->data, *optlen); + /* It cannot free tp->saved_syn here because it + * does not know if the user space still needs it. + */ + return 0; + } + + if (optname == TCP_CONGESTION) { + if (!inet_csk(sk)->icsk_ca_ops) + return -EINVAL; + /* BPF expects NULL-terminated tcp-cc string */ + optval[--(*optlen)] = '\0'; + } + + return do_tcp_getsockopt(sk, SOL_TCP, optname, + KERNEL_SOCKPTR(optval), + KERNEL_SOCKPTR(optlen)); } return do_tcp_setsockopt(sk, SOL_TCP, optname, - KERNEL_SOCKPTR(optval), optlen); + KERNEL_SOCKPTR(optval), *optlen); } static int sol_ip_setsockopt(struct sock *sk, int optname, @@ -5183,7 +5218,7 @@ static int __bpf_setsockopt(struct sock *sk, int level, int optname, else if (IS_ENABLED(CONFIG_IPV6) && level == SOL_IPV6) return sol_ipv6_setsockopt(sk, optname, optval, optlen); else if (IS_ENABLED(CONFIG_INET) && level == SOL_TCP) - return sol_tcp_setsockopt(sk, optname, optval, optlen); + return sol_tcp_sockopt(sk, optname, optval, &optlen, false); return -EINVAL; } @@ -5206,31 +5241,8 @@ static int __bpf_getsockopt(struct sock *sk, int level, int optname, if (level == SOL_SOCKET) { err = sol_socket_sockopt(sk, optname, optval, &optlen, true); - } else if (IS_ENABLED(CONFIG_INET) && - level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) { - struct inet_connection_sock *icsk; - struct tcp_sock *tp; - - switch (optname) { - case TCP_CONGESTION: - icsk = inet_csk(sk); - - if (!icsk->icsk_ca_ops || optlen <= 1) - goto err_clear; - strncpy(optval, icsk->icsk_ca_ops->name, optlen); - optval[optlen - 1] = 0; - break; - case TCP_SAVED_SYN: - tp = tcp_sk(sk); - - if (optlen <= 0 || !tp->saved_syn || - optlen > tcp_saved_syn_len(tp->saved_syn)) - goto err_clear; - memcpy(optval, tp->saved_syn->data, optlen); - break; - default: - goto err_clear; - } + } else if (IS_ENABLED(CONFIG_INET) && level == SOL_TCP) { + err = sol_tcp_sockopt(sk, optname, optval, &optlen, true); } else if (IS_ENABLED(CONFIG_INET) && level == SOL_IP) { struct inet_sock *inet = inet_sk(sk); diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 45c737ee95a1..a822cc627e2a 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4043,8 +4043,8 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk, return stats; } -static int do_tcp_getsockopt(struct sock *sk, int level, - int optname, sockptr_t optval, sockptr_t optlen) +int do_tcp_getsockopt(struct sock *sk, int level, + int optname, sockptr_t optval, sockptr_t optlen) { struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk);