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Commit 8c4b4c7e authored by Lawrence Brakmo's avatar Lawrence Brakmo Committed by David S. Miller
Browse files

bpf: Add setsockopt helper function to bpf 



Added support for calling a subset of socket setsockopts from
BPF_PROG_TYPE_SOCK_OPS programs. The code was duplicated rather
than making the changes to call the socket setsockopt function because
the changes required would have been larger.

The ops supported are:
  SO_RCVBUF
  SO_SNDBUF
  SO_MAX_PACING_RATE
  SO_PRIORITY
  SO_RCVLOWAT
  SO_MARK

Signed-off-by: default avatarLawrence Brakmo <brakmo@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c400296b

include/uapi/linux/bpf.h

+13 −1
Original line number Diff line number Diff line
@@ -520,6 +520,17 @@ union bpf_attr { 
 *     Set full skb->hash.

 *     @skb: pointer to skb

 *     @hash: hash to set

 *

 * int bpf_setsockopt(bpf_socket, level, optname, optval, optlen)

 *     Calls setsockopt. Not all opts are available, only those with

 *     integer optvals plus TCP_CONGESTION.

 *     Supported levels: SOL_SOCKET and IPROTO_TCP

 *     @bpf_socket: pointer to bpf_socket

 *     @level: SOL_SOCKET or IPROTO_TCP

 *     @optname: option name

 *     @optval: pointer to option value

 *     @optlen: length of optval in byes

 *     Return: 0 or negative error

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -570,7 +581,8 @@ union bpf_attr { 
	FN(probe_read_str),		\

	FN(get_socket_cookie),		\

	FN(get_socket_uid),		\

	FN(set_hash),

	FN(set_hash),			\

	FN(setsockopt),



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call

net/core/filter.c

+78 −1
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ 
#include <net/dst.h>

#include <net/sock_reuseport.h>

#include <net/busy_poll.h>

#include <net/tcp.h>



/**

 *	sk_filter_trim_cap - run a packet through a socket filter
@@ -2672,6 +2673,71 @@ static const struct bpf_func_proto bpf_get_socket_uid_proto = { 
	.arg1_type      = ARG_PTR_TO_CTX,

};



BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,

	   int, level, int, optname, char *, optval, int, optlen)

{

	struct sock *sk = bpf_sock->sk;

	int ret = 0;

	int val;



	if (!sk_fullsock(sk))

		return -EINVAL;



	if (level == SOL_SOCKET) {

		if (optlen != sizeof(int))

			return -EINVAL;

		val = *((int *)optval);



		/* Only some socketops are supported */

		switch (optname) {

		case SO_RCVBUF:

			sk->sk_userlocks |= SOCK_RCVBUF_LOCK;

			sk->sk_rcvbuf = max_t(int, val * 2, SOCK_MIN_RCVBUF);

			break;

		case SO_SNDBUF:

			sk->sk_userlocks |= SOCK_SNDBUF_LOCK;

			sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);

			break;

		case SO_MAX_PACING_RATE:

			sk->sk_max_pacing_rate = val;

			sk->sk_pacing_rate = min(sk->sk_pacing_rate,

						 sk->sk_max_pacing_rate);

			break;

		case SO_PRIORITY:

			sk->sk_priority = val;

			break;

		case SO_RCVLOWAT:

			if (val < 0)

				val = INT_MAX;

			sk->sk_rcvlowat = val ? : 1;

			break;

		case SO_MARK:

			sk->sk_mark = val;

			break;

		default:

			ret = -EINVAL;

		}

	} else if (level == SOL_TCP &&

		   sk->sk_prot->setsockopt == tcp_setsockopt) {

		/* Place holder */

		ret = -EINVAL;

	} else {

		ret = -EINVAL;

	}

	return ret;

}



static const struct bpf_func_proto bpf_setsockopt_proto = {

	.func		= bpf_setsockopt,

	.gpl_only	= true,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_CTX,

	.arg2_type	= ARG_ANYTHING,

	.arg3_type	= ARG_ANYTHING,

	.arg4_type	= ARG_PTR_TO_MEM,

	.arg5_type	= ARG_CONST_SIZE,

};



static const struct bpf_func_proto *

bpf_base_func_proto(enum bpf_func_id func_id)

{
@@ -2822,6 +2888,17 @@ lwt_inout_func_proto(enum bpf_func_id func_id) 
	}

}



static const struct bpf_func_proto *

	sock_ops_func_proto(enum bpf_func_id func_id)

{

	switch (func_id) {

	case BPF_FUNC_setsockopt:

		return &bpf_setsockopt_proto;

	default:

		return bpf_base_func_proto(func_id);

	}

}



static const struct bpf_func_proto *

lwt_xmit_func_proto(enum bpf_func_id func_id)

{
@@ -3591,7 +3668,7 @@ const struct bpf_verifier_ops cg_sock_prog_ops = { 
};



const struct bpf_verifier_ops sock_ops_prog_ops = {

	.get_func_proto		= bpf_base_func_proto,

	.get_func_proto		= sock_ops_func_proto,

	.is_valid_access	= sock_ops_is_valid_access,

	.convert_ctx_access	= sock_ops_convert_ctx_access,

};

samples/bpf/bpf_helpers.h

+3 −0
Original line number Diff line number Diff line
@@ -60,6 +60,9 @@ static unsigned long long (*bpf_get_prandom_u32)(void) = 
	(void *) BPF_FUNC_get_prandom_u32;

static int (*bpf_xdp_adjust_head)(void *ctx, int offset) =

	(void *) BPF_FUNC_xdp_adjust_head;

static int (*bpf_setsockopt)(void *ctx, int level, int optname, void *optval,

			     int optlen) =

	(void *) BPF_FUNC_setsockopt;



/* llvm builtin functions that eBPF C program may use to

 * emit BPF_LD_ABS and BPF_LD_IND instructions