Commit 273b7f0f authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
Browse files

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: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002918.2894511-1-kafai@fb.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 65ddc82d

include/net/tcp.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

net/core/filter.c

+43 −31
Original line number Diff line number Diff line
@@ -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);

net/ipv4/tcp.c

+2 −2
Original line number Diff line number Diff line
@@ -4043,7 +4043,7 @@ 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 do_tcp_getsockopt(struct sock *sk, int level,

		      int optname, sockptr_t optval, sockptr_t optlen)

{

	struct inet_connection_sock *icsk = inet_csk(sk);