cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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net.c (17536B)


      1// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
      2// Copyright (C) 2018 Facebook
      3
      4#define _GNU_SOURCE
      5#include <errno.h>
      6#include <fcntl.h>
      7#include <stdlib.h>
      8#include <string.h>
      9#include <time.h>
     10#include <unistd.h>
     11#include <bpf/bpf.h>
     12#include <bpf/libbpf.h>
     13#include <net/if.h>
     14#include <linux/rtnetlink.h>
     15#include <linux/socket.h>
     16#include <linux/tc_act/tc_bpf.h>
     17#include <sys/socket.h>
     18#include <sys/stat.h>
     19#include <sys/types.h>
     20
     21#include "bpf/nlattr.h"
     22#include "main.h"
     23#include "netlink_dumper.h"
     24
     25#ifndef SOL_NETLINK
     26#define SOL_NETLINK 270
     27#endif
     28
     29struct ip_devname_ifindex {
     30	char	devname[64];
     31	int	ifindex;
     32};
     33
     34struct bpf_netdev_t {
     35	struct ip_devname_ifindex *devices;
     36	int	used_len;
     37	int	array_len;
     38	int	filter_idx;
     39};
     40
     41struct tc_kind_handle {
     42	char	kind[64];
     43	int	handle;
     44};
     45
     46struct bpf_tcinfo_t {
     47	struct tc_kind_handle	*handle_array;
     48	int			used_len;
     49	int			array_len;
     50	bool			is_qdisc;
     51};
     52
     53struct bpf_filter_t {
     54	const char	*kind;
     55	const char	*devname;
     56	int		ifindex;
     57};
     58
     59struct bpf_attach_info {
     60	__u32 flow_dissector_id;
     61};
     62
     63enum net_attach_type {
     64	NET_ATTACH_TYPE_XDP,
     65	NET_ATTACH_TYPE_XDP_GENERIC,
     66	NET_ATTACH_TYPE_XDP_DRIVER,
     67	NET_ATTACH_TYPE_XDP_OFFLOAD,
     68};
     69
     70static const char * const attach_type_strings[] = {
     71	[NET_ATTACH_TYPE_XDP]		= "xdp",
     72	[NET_ATTACH_TYPE_XDP_GENERIC]	= "xdpgeneric",
     73	[NET_ATTACH_TYPE_XDP_DRIVER]	= "xdpdrv",
     74	[NET_ATTACH_TYPE_XDP_OFFLOAD]	= "xdpoffload",
     75};
     76
     77const size_t net_attach_type_size = ARRAY_SIZE(attach_type_strings);
     78
     79static enum net_attach_type parse_attach_type(const char *str)
     80{
     81	enum net_attach_type type;
     82
     83	for (type = 0; type < net_attach_type_size; type++) {
     84		if (attach_type_strings[type] &&
     85		    is_prefix(str, attach_type_strings[type]))
     86			return type;
     87	}
     88
     89	return net_attach_type_size;
     90}
     91
     92typedef int (*dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
     93
     94typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, dump_nlmsg_t, void *cookie);
     95
     96static int netlink_open(__u32 *nl_pid)
     97{
     98	struct sockaddr_nl sa;
     99	socklen_t addrlen;
    100	int one = 1, ret;
    101	int sock;
    102
    103	memset(&sa, 0, sizeof(sa));
    104	sa.nl_family = AF_NETLINK;
    105
    106	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
    107	if (sock < 0)
    108		return -errno;
    109
    110	if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
    111		       &one, sizeof(one)) < 0) {
    112		p_err("Netlink error reporting not supported");
    113	}
    114
    115	if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
    116		ret = -errno;
    117		goto cleanup;
    118	}
    119
    120	addrlen = sizeof(sa);
    121	if (getsockname(sock, (struct sockaddr *)&sa, &addrlen) < 0) {
    122		ret = -errno;
    123		goto cleanup;
    124	}
    125
    126	if (addrlen != sizeof(sa)) {
    127		ret = -LIBBPF_ERRNO__INTERNAL;
    128		goto cleanup;
    129	}
    130
    131	*nl_pid = sa.nl_pid;
    132	return sock;
    133
    134cleanup:
    135	close(sock);
    136	return ret;
    137}
    138
    139static int netlink_recv(int sock, __u32 nl_pid, __u32 seq,
    140			    __dump_nlmsg_t _fn, dump_nlmsg_t fn,
    141			    void *cookie)
    142{
    143	bool multipart = true;
    144	struct nlmsgerr *err;
    145	struct nlmsghdr *nh;
    146	char buf[4096];
    147	int len, ret;
    148
    149	while (multipart) {
    150		multipart = false;
    151		len = recv(sock, buf, sizeof(buf), 0);
    152		if (len < 0) {
    153			ret = -errno;
    154			goto done;
    155		}
    156
    157		if (len == 0)
    158			break;
    159
    160		for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, (unsigned int)len);
    161		     nh = NLMSG_NEXT(nh, len)) {
    162			if (nh->nlmsg_pid != nl_pid) {
    163				ret = -LIBBPF_ERRNO__WRNGPID;
    164				goto done;
    165			}
    166			if (nh->nlmsg_seq != seq) {
    167				ret = -LIBBPF_ERRNO__INVSEQ;
    168				goto done;
    169			}
    170			if (nh->nlmsg_flags & NLM_F_MULTI)
    171				multipart = true;
    172			switch (nh->nlmsg_type) {
    173			case NLMSG_ERROR:
    174				err = (struct nlmsgerr *)NLMSG_DATA(nh);
    175				if (!err->error)
    176					continue;
    177				ret = err->error;
    178				libbpf_nla_dump_errormsg(nh);
    179				goto done;
    180			case NLMSG_DONE:
    181				return 0;
    182			default:
    183				break;
    184			}
    185			if (_fn) {
    186				ret = _fn(nh, fn, cookie);
    187				if (ret)
    188					return ret;
    189			}
    190		}
    191	}
    192	ret = 0;
    193done:
    194	return ret;
    195}
    196
    197static int __dump_class_nlmsg(struct nlmsghdr *nlh,
    198			      dump_nlmsg_t dump_class_nlmsg,
    199			      void *cookie)
    200{
    201	struct nlattr *tb[TCA_MAX + 1], *attr;
    202	struct tcmsg *t = NLMSG_DATA(nlh);
    203	int len;
    204
    205	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
    206	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
    207	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
    208		return -LIBBPF_ERRNO__NLPARSE;
    209
    210	return dump_class_nlmsg(cookie, t, tb);
    211}
    212
    213static int netlink_get_class(int sock, unsigned int nl_pid, int ifindex,
    214			     dump_nlmsg_t dump_class_nlmsg, void *cookie)
    215{
    216	struct {
    217		struct nlmsghdr nlh;
    218		struct tcmsg t;
    219	} req = {
    220		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
    221		.nlh.nlmsg_type = RTM_GETTCLASS,
    222		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
    223		.t.tcm_family = AF_UNSPEC,
    224		.t.tcm_ifindex = ifindex,
    225	};
    226	int seq = time(NULL);
    227
    228	req.nlh.nlmsg_seq = seq;
    229	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
    230		return -errno;
    231
    232	return netlink_recv(sock, nl_pid, seq, __dump_class_nlmsg,
    233			    dump_class_nlmsg, cookie);
    234}
    235
    236static int __dump_qdisc_nlmsg(struct nlmsghdr *nlh,
    237			      dump_nlmsg_t dump_qdisc_nlmsg,
    238			      void *cookie)
    239{
    240	struct nlattr *tb[TCA_MAX + 1], *attr;
    241	struct tcmsg *t = NLMSG_DATA(nlh);
    242	int len;
    243
    244	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
    245	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
    246	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
    247		return -LIBBPF_ERRNO__NLPARSE;
    248
    249	return dump_qdisc_nlmsg(cookie, t, tb);
    250}
    251
    252static int netlink_get_qdisc(int sock, unsigned int nl_pid, int ifindex,
    253			     dump_nlmsg_t dump_qdisc_nlmsg, void *cookie)
    254{
    255	struct {
    256		struct nlmsghdr nlh;
    257		struct tcmsg t;
    258	} req = {
    259		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
    260		.nlh.nlmsg_type = RTM_GETQDISC,
    261		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
    262		.t.tcm_family = AF_UNSPEC,
    263		.t.tcm_ifindex = ifindex,
    264	};
    265	int seq = time(NULL);
    266
    267	req.nlh.nlmsg_seq = seq;
    268	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
    269		return -errno;
    270
    271	return netlink_recv(sock, nl_pid, seq, __dump_qdisc_nlmsg,
    272			    dump_qdisc_nlmsg, cookie);
    273}
    274
    275static int __dump_filter_nlmsg(struct nlmsghdr *nlh,
    276			       dump_nlmsg_t dump_filter_nlmsg,
    277			       void *cookie)
    278{
    279	struct nlattr *tb[TCA_MAX + 1], *attr;
    280	struct tcmsg *t = NLMSG_DATA(nlh);
    281	int len;
    282
    283	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
    284	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
    285	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
    286		return -LIBBPF_ERRNO__NLPARSE;
    287
    288	return dump_filter_nlmsg(cookie, t, tb);
    289}
    290
    291static int netlink_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,
    292			      dump_nlmsg_t dump_filter_nlmsg, void *cookie)
    293{
    294	struct {
    295		struct nlmsghdr nlh;
    296		struct tcmsg t;
    297	} req = {
    298		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
    299		.nlh.nlmsg_type = RTM_GETTFILTER,
    300		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
    301		.t.tcm_family = AF_UNSPEC,
    302		.t.tcm_ifindex = ifindex,
    303		.t.tcm_parent = handle,
    304	};
    305	int seq = time(NULL);
    306
    307	req.nlh.nlmsg_seq = seq;
    308	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
    309		return -errno;
    310
    311	return netlink_recv(sock, nl_pid, seq, __dump_filter_nlmsg,
    312			    dump_filter_nlmsg, cookie);
    313}
    314
    315static int __dump_link_nlmsg(struct nlmsghdr *nlh,
    316			     dump_nlmsg_t dump_link_nlmsg, void *cookie)
    317{
    318	struct nlattr *tb[IFLA_MAX + 1], *attr;
    319	struct ifinfomsg *ifi = NLMSG_DATA(nlh);
    320	int len;
    321
    322	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*ifi));
    323	attr = (struct nlattr *) ((void *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
    324	if (libbpf_nla_parse(tb, IFLA_MAX, attr, len, NULL) != 0)
    325		return -LIBBPF_ERRNO__NLPARSE;
    326
    327	return dump_link_nlmsg(cookie, ifi, tb);
    328}
    329
    330static int netlink_get_link(int sock, unsigned int nl_pid,
    331			    dump_nlmsg_t dump_link_nlmsg, void *cookie)
    332{
    333	struct {
    334		struct nlmsghdr nlh;
    335		struct ifinfomsg ifm;
    336	} req = {
    337		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
    338		.nlh.nlmsg_type = RTM_GETLINK,
    339		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
    340		.ifm.ifi_family = AF_PACKET,
    341	};
    342	int seq = time(NULL);
    343
    344	req.nlh.nlmsg_seq = seq;
    345	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
    346		return -errno;
    347
    348	return netlink_recv(sock, nl_pid, seq, __dump_link_nlmsg,
    349			    dump_link_nlmsg, cookie);
    350}
    351
    352static int dump_link_nlmsg(void *cookie, void *msg, struct nlattr **tb)
    353{
    354	struct bpf_netdev_t *netinfo = cookie;
    355	struct ifinfomsg *ifinfo = msg;
    356
    357	if (netinfo->filter_idx > 0 && netinfo->filter_idx != ifinfo->ifi_index)
    358		return 0;
    359
    360	if (netinfo->used_len == netinfo->array_len) {
    361		netinfo->devices = realloc(netinfo->devices,
    362			(netinfo->array_len + 16) *
    363			sizeof(struct ip_devname_ifindex));
    364		if (!netinfo->devices)
    365			return -ENOMEM;
    366
    367		netinfo->array_len += 16;
    368	}
    369	netinfo->devices[netinfo->used_len].ifindex = ifinfo->ifi_index;
    370	snprintf(netinfo->devices[netinfo->used_len].devname,
    371		 sizeof(netinfo->devices[netinfo->used_len].devname),
    372		 "%s",
    373		 tb[IFLA_IFNAME]
    374			 ? libbpf_nla_getattr_str(tb[IFLA_IFNAME])
    375			 : "");
    376	netinfo->used_len++;
    377
    378	return do_xdp_dump(ifinfo, tb);
    379}
    380
    381static int dump_class_qdisc_nlmsg(void *cookie, void *msg, struct nlattr **tb)
    382{
    383	struct bpf_tcinfo_t *tcinfo = cookie;
    384	struct tcmsg *info = msg;
    385
    386	if (tcinfo->is_qdisc) {
    387		/* skip clsact qdisc */
    388		if (tb[TCA_KIND] &&
    389		    strcmp(libbpf_nla_data(tb[TCA_KIND]), "clsact") == 0)
    390			return 0;
    391		if (info->tcm_handle == 0)
    392			return 0;
    393	}
    394
    395	if (tcinfo->used_len == tcinfo->array_len) {
    396		tcinfo->handle_array = realloc(tcinfo->handle_array,
    397			(tcinfo->array_len + 16) * sizeof(struct tc_kind_handle));
    398		if (!tcinfo->handle_array)
    399			return -ENOMEM;
    400
    401		tcinfo->array_len += 16;
    402	}
    403	tcinfo->handle_array[tcinfo->used_len].handle = info->tcm_handle;
    404	snprintf(tcinfo->handle_array[tcinfo->used_len].kind,
    405		 sizeof(tcinfo->handle_array[tcinfo->used_len].kind),
    406		 "%s",
    407		 tb[TCA_KIND]
    408			 ? libbpf_nla_getattr_str(tb[TCA_KIND])
    409			 : "unknown");
    410	tcinfo->used_len++;
    411
    412	return 0;
    413}
    414
    415static int dump_filter_nlmsg(void *cookie, void *msg, struct nlattr **tb)
    416{
    417	const struct bpf_filter_t *filter_info = cookie;
    418
    419	return do_filter_dump((struct tcmsg *)msg, tb, filter_info->kind,
    420			      filter_info->devname, filter_info->ifindex);
    421}
    422
    423static int show_dev_tc_bpf(int sock, unsigned int nl_pid,
    424			   struct ip_devname_ifindex *dev)
    425{
    426	struct bpf_filter_t filter_info;
    427	struct bpf_tcinfo_t tcinfo;
    428	int i, handle, ret = 0;
    429
    430	tcinfo.handle_array = NULL;
    431	tcinfo.used_len = 0;
    432	tcinfo.array_len = 0;
    433
    434	tcinfo.is_qdisc = false;
    435	ret = netlink_get_class(sock, nl_pid, dev->ifindex,
    436				dump_class_qdisc_nlmsg, &tcinfo);
    437	if (ret)
    438		goto out;
    439
    440	tcinfo.is_qdisc = true;
    441	ret = netlink_get_qdisc(sock, nl_pid, dev->ifindex,
    442				dump_class_qdisc_nlmsg, &tcinfo);
    443	if (ret)
    444		goto out;
    445
    446	filter_info.devname = dev->devname;
    447	filter_info.ifindex = dev->ifindex;
    448	for (i = 0; i < tcinfo.used_len; i++) {
    449		filter_info.kind = tcinfo.handle_array[i].kind;
    450		ret = netlink_get_filter(sock, nl_pid, dev->ifindex,
    451					 tcinfo.handle_array[i].handle,
    452					 dump_filter_nlmsg, &filter_info);
    453		if (ret)
    454			goto out;
    455	}
    456
    457	/* root, ingress and egress handle */
    458	handle = TC_H_ROOT;
    459	filter_info.kind = "root";
    460	ret = netlink_get_filter(sock, nl_pid, dev->ifindex, handle,
    461				 dump_filter_nlmsg, &filter_info);
    462	if (ret)
    463		goto out;
    464
    465	handle = TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_INGRESS);
    466	filter_info.kind = "clsact/ingress";
    467	ret = netlink_get_filter(sock, nl_pid, dev->ifindex, handle,
    468				 dump_filter_nlmsg, &filter_info);
    469	if (ret)
    470		goto out;
    471
    472	handle = TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_EGRESS);
    473	filter_info.kind = "clsact/egress";
    474	ret = netlink_get_filter(sock, nl_pid, dev->ifindex, handle,
    475				 dump_filter_nlmsg, &filter_info);
    476	if (ret)
    477		goto out;
    478
    479out:
    480	free(tcinfo.handle_array);
    481	return 0;
    482}
    483
    484static int query_flow_dissector(struct bpf_attach_info *attach_info)
    485{
    486	__u32 attach_flags;
    487	__u32 prog_ids[1];
    488	__u32 prog_cnt;
    489	int err;
    490	int fd;
    491
    492	fd = open("/proc/self/ns/net", O_RDONLY);
    493	if (fd < 0) {
    494		p_err("can't open /proc/self/ns/net: %s",
    495		      strerror(errno));
    496		return -1;
    497	}
    498	prog_cnt = ARRAY_SIZE(prog_ids);
    499	err = bpf_prog_query(fd, BPF_FLOW_DISSECTOR, 0,
    500			     &attach_flags, prog_ids, &prog_cnt);
    501	close(fd);
    502	if (err) {
    503		if (errno == EINVAL) {
    504			/* Older kernel's don't support querying
    505			 * flow dissector programs.
    506			 */
    507			errno = 0;
    508			return 0;
    509		}
    510		p_err("can't query prog: %s", strerror(errno));
    511		return -1;
    512	}
    513
    514	if (prog_cnt == 1)
    515		attach_info->flow_dissector_id = prog_ids[0];
    516
    517	return 0;
    518}
    519
    520static int net_parse_dev(int *argc, char ***argv)
    521{
    522	int ifindex;
    523
    524	if (is_prefix(**argv, "dev")) {
    525		NEXT_ARGP();
    526
    527		ifindex = if_nametoindex(**argv);
    528		if (!ifindex)
    529			p_err("invalid devname %s", **argv);
    530
    531		NEXT_ARGP();
    532	} else {
    533		p_err("expected 'dev', got: '%s'?", **argv);
    534		return -1;
    535	}
    536
    537	return ifindex;
    538}
    539
    540static int do_attach_detach_xdp(int progfd, enum net_attach_type attach_type,
    541				int ifindex, bool overwrite)
    542{
    543	__u32 flags = 0;
    544
    545	if (!overwrite)
    546		flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
    547	if (attach_type == NET_ATTACH_TYPE_XDP_GENERIC)
    548		flags |= XDP_FLAGS_SKB_MODE;
    549	if (attach_type == NET_ATTACH_TYPE_XDP_DRIVER)
    550		flags |= XDP_FLAGS_DRV_MODE;
    551	if (attach_type == NET_ATTACH_TYPE_XDP_OFFLOAD)
    552		flags |= XDP_FLAGS_HW_MODE;
    553
    554	return bpf_xdp_attach(ifindex, progfd, flags, NULL);
    555}
    556
    557static int do_attach(int argc, char **argv)
    558{
    559	enum net_attach_type attach_type;
    560	int progfd, ifindex, err = 0;
    561	bool overwrite = false;
    562
    563	/* parse attach args */
    564	if (!REQ_ARGS(5))
    565		return -EINVAL;
    566
    567	attach_type = parse_attach_type(*argv);
    568	if (attach_type == net_attach_type_size) {
    569		p_err("invalid net attach/detach type: %s", *argv);
    570		return -EINVAL;
    571	}
    572	NEXT_ARG();
    573
    574	progfd = prog_parse_fd(&argc, &argv);
    575	if (progfd < 0)
    576		return -EINVAL;
    577
    578	ifindex = net_parse_dev(&argc, &argv);
    579	if (ifindex < 1) {
    580		err = -EINVAL;
    581		goto cleanup;
    582	}
    583
    584	if (argc) {
    585		if (is_prefix(*argv, "overwrite")) {
    586			overwrite = true;
    587		} else {
    588			p_err("expected 'overwrite', got: '%s'?", *argv);
    589			err = -EINVAL;
    590			goto cleanup;
    591		}
    592	}
    593
    594	/* attach xdp prog */
    595	if (is_prefix("xdp", attach_type_strings[attach_type]))
    596		err = do_attach_detach_xdp(progfd, attach_type, ifindex,
    597					   overwrite);
    598	if (err) {
    599		p_err("interface %s attach failed: %s",
    600		      attach_type_strings[attach_type], strerror(-err));
    601		goto cleanup;
    602	}
    603
    604	if (json_output)
    605		jsonw_null(json_wtr);
    606cleanup:
    607	close(progfd);
    608	return err;
    609}
    610
    611static int do_detach(int argc, char **argv)
    612{
    613	enum net_attach_type attach_type;
    614	int progfd, ifindex, err = 0;
    615
    616	/* parse detach args */
    617	if (!REQ_ARGS(3))
    618		return -EINVAL;
    619
    620	attach_type = parse_attach_type(*argv);
    621	if (attach_type == net_attach_type_size) {
    622		p_err("invalid net attach/detach type: %s", *argv);
    623		return -EINVAL;
    624	}
    625	NEXT_ARG();
    626
    627	ifindex = net_parse_dev(&argc, &argv);
    628	if (ifindex < 1)
    629		return -EINVAL;
    630
    631	/* detach xdp prog */
    632	progfd = -1;
    633	if (is_prefix("xdp", attach_type_strings[attach_type]))
    634		err = do_attach_detach_xdp(progfd, attach_type, ifindex, NULL);
    635
    636	if (err < 0) {
    637		p_err("interface %s detach failed: %s",
    638		      attach_type_strings[attach_type], strerror(-err));
    639		return err;
    640	}
    641
    642	if (json_output)
    643		jsonw_null(json_wtr);
    644
    645	return 0;
    646}
    647
    648static int do_show(int argc, char **argv)
    649{
    650	struct bpf_attach_info attach_info = {};
    651	int i, sock, ret, filter_idx = -1;
    652	struct bpf_netdev_t dev_array;
    653	unsigned int nl_pid = 0;
    654	char err_buf[256];
    655
    656	if (argc == 2) {
    657		filter_idx = net_parse_dev(&argc, &argv);
    658		if (filter_idx < 1)
    659			return -1;
    660	} else if (argc != 0) {
    661		usage();
    662	}
    663
    664	ret = query_flow_dissector(&attach_info);
    665	if (ret)
    666		return -1;
    667
    668	sock = netlink_open(&nl_pid);
    669	if (sock < 0) {
    670		fprintf(stderr, "failed to open netlink sock\n");
    671		return -1;
    672	}
    673
    674	dev_array.devices = NULL;
    675	dev_array.used_len = 0;
    676	dev_array.array_len = 0;
    677	dev_array.filter_idx = filter_idx;
    678
    679	if (json_output)
    680		jsonw_start_array(json_wtr);
    681	NET_START_OBJECT;
    682	NET_START_ARRAY("xdp", "%s:\n");
    683	ret = netlink_get_link(sock, nl_pid, dump_link_nlmsg, &dev_array);
    684	NET_END_ARRAY("\n");
    685
    686	if (!ret) {
    687		NET_START_ARRAY("tc", "%s:\n");
    688		for (i = 0; i < dev_array.used_len; i++) {
    689			ret = show_dev_tc_bpf(sock, nl_pid,
    690					      &dev_array.devices[i]);
    691			if (ret)
    692				break;
    693		}
    694		NET_END_ARRAY("\n");
    695	}
    696
    697	NET_START_ARRAY("flow_dissector", "%s:\n");
    698	if (attach_info.flow_dissector_id > 0)
    699		NET_DUMP_UINT("id", "id %u", attach_info.flow_dissector_id);
    700	NET_END_ARRAY("\n");
    701
    702	NET_END_OBJECT;
    703	if (json_output)
    704		jsonw_end_array(json_wtr);
    705
    706	if (ret) {
    707		if (json_output)
    708			jsonw_null(json_wtr);
    709		libbpf_strerror(ret, err_buf, sizeof(err_buf));
    710		fprintf(stderr, "Error: %s\n", err_buf);
    711	}
    712	free(dev_array.devices);
    713	close(sock);
    714	return ret;
    715}
    716
    717static int do_help(int argc, char **argv)
    718{
    719	if (json_output) {
    720		jsonw_null(json_wtr);
    721		return 0;
    722	}
    723
    724	fprintf(stderr,
    725		"Usage: %1$s %2$s { show | list } [dev <devname>]\n"
    726		"       %1$s %2$s attach ATTACH_TYPE PROG dev <devname> [ overwrite ]\n"
    727		"       %1$s %2$s detach ATTACH_TYPE dev <devname>\n"
    728		"       %1$s %2$s help\n"
    729		"\n"
    730		"       " HELP_SPEC_PROGRAM "\n"
    731		"       ATTACH_TYPE := { xdp | xdpgeneric | xdpdrv | xdpoffload }\n"
    732		"       " HELP_SPEC_OPTIONS " }\n"
    733		"\n"
    734		"Note: Only xdp and tc attachments are supported now.\n"
    735		"      For progs attached to cgroups, use \"bpftool cgroup\"\n"
    736		"      to dump program attachments. For program types\n"
    737		"      sk_{filter,skb,msg,reuseport} and lwt/seg6, please\n"
    738		"      consult iproute2.\n"
    739		"",
    740		bin_name, argv[-2]);
    741
    742	return 0;
    743}
    744
    745static const struct cmd cmds[] = {
    746	{ "show",	do_show },
    747	{ "list",	do_show },
    748	{ "attach",	do_attach },
    749	{ "detach",	do_detach },
    750	{ "help",	do_help },
    751	{ 0 }
    752};
    753
    754int do_net(int argc, char **argv)
    755{
    756	return cmd_select(cmds, argc, argv, do_help);
    757}