path: root/tools/lib/bpf/netlink.c

// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2018 Facebook */

#include <stdlib.h>
#include <memory.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/pkt_cls.h>
#include <linux/rtnetlink.h>
#include <linux/netdev.h>
#include <sys/socket.h>
#include <errno.h>
#include <time.h>

#include "bpf.h"
#include "libbpf.h"
#include "libbpf_internal.h"
#include "nlattr.h"

#ifndef SOL_NETLINK
#define SOL_NETLINK 270
#endif

typedef int (*libbpf_dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);

typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, libbpf_dump_nlmsg_t,
			      void *cookie);

struct xdp_link_info {
	__u32 prog_id;
	__u32 drv_prog_id;
	__u32 hw_prog_id;
	__u32 skb_prog_id;
	__u8 attach_mode;
};

struct xdp_id_md {
	int ifindex;
	__u32 flags;
	struct xdp_link_info info;
	__u64 feature_flags;
};

struct xdp_features_md {
	int ifindex;
	__u32 xdp_zc_max_segs;
	__u64 flags;
};

static int libbpf_netlink_open(__u32 *nl_pid, int proto)
{
	struct sockaddr_nl sa;
	socklen_t addrlen;
	int one = 1, ret;
	int sock;

	memset(&sa, 0, sizeof(sa));
	sa.nl_family = AF_NETLINK;

	sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, proto);
	if (sock < 0)
		return -errno;

	if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
		       &one, sizeof(one)) < 0) {
		pr_warn("Netlink error reporting not supported\n");
	}

	if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
		ret = -errno;
		goto cleanup;
	}

	addrlen = sizeof(sa);
	if (getsockname(sock, (struct sockaddr *)&sa, &addrlen) < 0) {
		ret = -errno;
		goto cleanup;
	}

	if (addrlen != sizeof(sa)) {
		ret = -LIBBPF_ERRNO__INTERNAL;
		goto cleanup;
	}

	*nl_pid = sa.nl_pid;
	return sock;

cleanup:
	close(sock);
	return ret;
}

static void libbpf_netlink_close(int sock)
{
	close(sock);
}

enum {
	NL_CONT,
	NL_NEXT,
	NL_DONE,
};

static int netlink_recvmsg(int sock, struct msghdr *mhdr, int flags)
{
	int len;

	do {
		len = recvmsg(sock, mhdr, flags);
	} while (len < 0 && (errno == EINTR || errno == EAGAIN));

	if (len < 0)
		return -errno;
	return len;
}

static int alloc_iov(struct iovec *iov, int len)
{
	void *nbuf;

	nbuf = realloc(iov->iov_base, len);
	if (!nbuf)
		return -ENOMEM;

	iov->iov_base = nbuf;
	iov->iov_len = len;
	return 0;
}

static int libbpf_netlink_recv(int sock, __u32 nl_pid, int seq,
			       __dump_nlmsg_t _fn, libbpf_dump_nlmsg_t fn,
			       void *cookie)
{
	struct iovec iov = {};
	struct msghdr mhdr = {
		.msg_iov = &iov,
		.msg_iovlen = 1,
	};
	bool multipart = true;
	struct nlmsgerr *err;
	struct nlmsghdr *nh;
	int len, ret;

	ret = alloc_iov(&iov, 4096);
	if (ret)
		goto done;

	while (multipart) {
start:
		multipart = false;
		len = netlink_recvmsg(sock, &mhdr, MSG_PEEK | MSG_TRUNC);
		if (len < 0) {
			ret = len;
			goto done;
		}

		if (len > iov.iov_len) {
			ret = alloc_iov(&iov, len);
			if (ret)
				goto done;
		}

		len = netlink_recvmsg(sock, &mhdr, 0);
		if (len < 0) {
			ret = len;
			goto done;
		}

		if (len == 0)
			break;

		for (nh = (struct nlmsghdr *)iov.iov_base; NLMSG_OK(nh, len);
		     nh = NLMSG_NEXT(nh, len)) {
			if (nh->nlmsg_pid != nl_pid) {
				ret = -LIBBPF_ERRNO__WRNGPID;
				goto done;
			}
			if (nh->nlmsg_seq != seq) {
				ret = -LIBBPF_ERRNO__INVSEQ;
				goto done;
			}
			if (nh->nlmsg_flags & NLM_F_MULTI)
				multipart = true;
			switch (nh->nlmsg_type) {
			case NLMSG_ERROR:
				err = (struct nlmsgerr *)NLMSG_DATA(nh);
				if (!err->error)
					continue;
				ret = err->error;
				libbpf_nla_dump_errormsg(nh);
				goto done;
			case NLMSG_DONE:
				ret = 0;
				goto done;
			default:
				break;
			}
			if (_fn) {
				ret = _fn(nh, fn, cookie);
				switch (ret) {
				case NL_CONT:
					break;
				case NL_NEXT:
					goto start;
				case NL_DONE:
					ret = 0;
					goto done;
				default:
					goto done;
				}
			}
		}
	}
	ret = 0;
done:
	free(iov.iov_base);
	return ret;
}

static int libbpf_netlink_send_recv(struct libbpf_nla_req *req,
				    int proto, __dump_nlmsg_t parse_msg,
				    libbpf_dump_nlmsg_t parse_attr,
				    void *cookie)
{
	__u32 nl_pid = 0;
	int sock, ret;

	sock = libbpf_netlink_open(&nl_pid, proto);
	if (sock < 0)
		return sock;

	req->nh.nlmsg_pid = 0;
	req->nh.nlmsg_seq = time(NULL);

	if (send(sock<