// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * inet_diag.c	Module for monitoring INET transport protocols sockets.
 *
 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/cache.h>
#include <linux/init.h>
#include <linux/time.h>

#include <net/icmp.h>
#include <net/tcp.h>
#include <net/ipv6.h>
#include <net/inet_common.h>
#include <net/inet_connection_sock.h>
#include <net/bpf_sk_storage.h>
#include <net/netlink.h>

#include <linux/inet.h>
#include <linux/stddef.h>

#include <linux/inet_diag.h>
#include <linux/sock_diag.h>

static const struct inet_diag_handler __rcu **inet_diag_table;

struct inet_diag_entry {
	const __be32 *saddr;
	const __be32 *daddr;
	u16 sport;
	u16 dport;
	u16 family;
	u16 userlocks;
	u32 ifindex;
	u32 mark;
#ifdef CONFIG_SOCK_CGROUP_DATA
	u64 cgroup_id;
#endif
};

static const struct inet_diag_handler *inet_diag_lock_handler(int proto)
{
	const struct inet_diag_handler *handler;

	if (proto < 0 || proto >= IPPROTO_MAX)
		return NULL;

	if (!READ_ONCE(inet_diag_table[proto]))
		sock_load_diag_module(AF_INET, proto);

	rcu_read_lock();
	handler = rcu_dereference(inet_diag_table[proto]);
	if (handler && !try_module_get(handler->owner))
		handler = NULL;
	rcu_read_unlock();

	return handler;
}

static void inet_diag_unlock_handler(const struct inet_diag_handler *handler)
{
	module_put(handler->owner);
}

void inet_diag_msg_common_fill(struct inet_diag_msg *r, struct sock *sk)
{
	r->idiag_family = READ_ONCE(sk->sk_family);

	r->id.idiag_sport = htons(READ_ONCE(sk->sk_num));
	r->id.idiag_dport = READ_ONCE(sk->sk_dport);
	r->id.idiag_if = READ_ONCE(sk->sk_bound_dev_if);
	sock_diag_save_cookie(sk, r->id.idiag_cookie);

#if IS_ENABLED(CONFIG_IPV6)
	if (r->idiag_family == AF_INET6) {
		data_race(*(struct in6_addr *)r->id.idiag_src = sk->sk_v6_rcv_saddr);
		data_race(*(struct in6_addr *)r->id.idiag_dst = sk->sk_v6_daddr);
	} else
#endif
	{
	memset(&r->id.idiag_src, 0, sizeof(r->id.idiag_src));
	memset(&r->id.idiag_dst, 0, sizeof(r->id.idiag_dst));

	r->id.idiag_src[0] = READ_ONCE(sk->sk_rcv_saddr);
	r->id.idiag_dst[0] = READ_ONCE(sk->sk_daddr);
	}
}
EXPORT_SYMBOL_GPL(inet_diag_msg_common_fill);

int inet_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb,
			     struct inet_diag_msg *r, int ext,
			     struct user_namespace *user_ns,
			     bool net_admin)
{
	const struct inet_sock *inet = inet_sk(sk);
	struct inet_diag_sockopt inet_sockopt;

	if (nla_put_u8(skb, INET_DIAG_SHUTDOWN, sk->sk_shutdown))
		goto errout;

	/* IPv6 dual-stack sockets use inet->tos for IPv4 connections,
	 * hence this needs to be included regardless of socket family.
	 */
	if (ext & (1 << (INET_DIAG_TOS - 1)))
		if (nla_put_u8(skb, INET_DIAG_TOS, READ_ONCE(inet->tos)) < 0)
			goto errout;

#if IS_ENABLED(CONFIG_IPV6)
	if (r->idiag_family == AF_INET6) {
		if (ext & (1 << (INET_DIAG_TCLASS - 1)))
			if (nla_put_u8(skb, INET_DIAG_TCLASS,
				       inet6_sk(sk)->tclass) < 0)
				goto errout;

		if (((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) &&
		    nla_put_u8(skb, INET_DIAG_SKV6ONLY, ipv6_only_sock(sk)))
			goto errout;
	}
#endif

	if (net_admin && nla_put_u32(skb, INET_DIAG_MARK, READ_ONCE(sk->sk_mark)))
		goto errout;

	if (ext & (1 << (INET_DIAG_CLASS_ID - 1)) ||
	    ext & (1 << (INET_DIAG_TCLASS - 1))) {
		u32 classid = 0;

#ifdef CONFIG_CGROUP_NET_CLASSID
		classid = sock_cgroup_classid(&sk->sk_cgrp_data);
#endif
		/* Fallback to socket priority if class id isn't set.
		 * Classful qdiscs use it as direct reference to class.
		 * For cgroup2 classid is always zero.
		 */
		if (!classid)
			classid = READ_ONCE(sk->sk_priority);

		if (nla_put_u32(skb, INET_DIAG_CLASS_ID, classid))
			goto errout;
	}

#ifdef CONFIG_SOCK_CGROUP_DATA
	if (nla_put_u64_64bit(skb, INET_DIAG_CGROUP_ID,
			      cgroup_id(sock_cgroup_ptr(&sk->sk_cgrp_data)),
			      INET_DIAG_PAD))
		goto errout;
#endif

	r->idiag_uid = from_kuid_munged(user_ns, sk_uid(sk));
	r->idiag_inode = sock_i_ino(sk);

	memset(&inet_sockopt, 0, sizeof(inet_sockopt));
	inet_sockopt.recverr	= inet_test_bit(RECVERR, sk);
	inet_sockopt.is_icsk	= inet_test_bit(IS_ICSK, sk);
	inet_sockopt.freebind	= inet_test_bit(FREEBIND, sk);
	inet_sockopt.hdrincl	= inet_test_bit(HDRINCL, sk);
	inet_sockopt.mc_loop	= inet_test_bit(MC_LOOP, sk);
	inet_sockopt.transparent = inet_test_bit(TRANSPARENT, sk);
	inet_sockopt.mc_all	= inet_test_bit(MC_ALL, sk);
	inet_sockopt.nodefrag	= inet_test_bit(NODEFRAG, sk);
	inet_sockopt.bind_address_no_port = inet_test_bit(BIND_ADDRESS_NO_PORT, sk);
	inet_sockopt.recverr_rfc4884 = inet_test_bit(RECVERR_RFC4884, sk);
	inet_sockopt.defer_connect = inet_test_bit(DEFER_CONNECT, sk);
	if (nla_put(skb, INET_DIAG_SOCKOPT, sizeof(inet_sockopt),
		    &inet_sockopt))
		goto errout;

	return 0;
errout:
	return 1;
}
EXPORT_SYMBOL_GPL(inet_diag_msg_attrs_fill);

static int inet_diag_parse_attrs(const struct nlmsghdr *nlh, int hdrlen,
				 struct nlattr **req_nlas)
{
	struct nlattr *nla;
	int remaining;

	nlmsg_for_each_attr(nla, nlh, hdrlen, remaining) {
		int type = nla_type(nla);

		if (type == INET_DIAG_REQ_PROTOCOL && nla_len(nla) != sizeof(u32))
			return -EINVAL;

		if (type < __INET_DIAG_REQ_MAX)
			req_nlas[type] = nla;
	}
	return 0;
}

static int inet_diag_get_protocol(const struct inet_diag_req_v2 *req,
				  const struct inet_diag_dump_data *data)
{
	if (data->req_nlas[INET_DIAG_REQ_PROTOCOL])
		return nla_get_u32(data->req_nlas[INET_DIAG_REQ_PROTOCOL]);
	return req->sdiag_protocol;
}

#define MAX_DUMP_ALLOC_SIZE (KMALLOC_MAX_SIZE - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))

int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
		      struct sk_buff *skb, struct netlink_callback *cb,
		      const struct inet_diag_req_v2 *req,
		      u16 nlmsg_flags, bool net_admin)
{
	const struct tcp_congestion_ops *ca_ops;
	const struct inet_diag_handler *handler;
	struct inet_diag_dump_data *cb_data;
	int ext = req->idiag_ext;
	struct inet_diag_msg *r;
	struct nlmsghdr  *nlh;
	struct nlattr *attr;
	void *info = NULL;
	u8 icsk_pending;
	int protocol;

	cb_data = cb->data;
	protocol = inet_diag_get_protocol(req, cb_data);

	/* inet_diag_lock_handler() made sure inet_diag_table[] is stable. */
	handler = rcu_dereference_protected(inet_diag_table[protocol], 1);
	DEBUG_NET_WARN_ON_ONCE(!handler);
	if (!handler)
		return -ENXIO;

	nlh = nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
			cb->nlh->nlmsg_type, sizeof(*r), nlmsg_flags);
	if (!nlh)
		return -EMSGSIZE;

	r = nlmsg_data(nlh);
	BUG_ON(!sk_fullsock(sk));

	inet_diag_msg_common_fill(r, sk);
	r->idiag_state = sk->sk_state;
	r->idiag_timer = 0;
	r->idiag_retrans = 0;
	r->idiag_expires = 0;

	if (inet_diag_msg_attrs_fill(sk, skb, r, ext,
				     sk_user_ns(NETLINK_CB(cb->skb).sk),
				     net_admin))
		goto errout;

	if (ext & (1 << (INET_DIAG_MEMINFO - 1))) {
		struct inet_diag_meminfo minfo = {
			.idiag_rmem = sk_rmem_alloc_get(sk),
			.idiag_wmem = READ_ONCE(sk->sk_wmem_queued),
			.idiag_fmem = READ_ONCE(sk->sk_forward_alloc),
			.idiag_tmem = sk_wmem_alloc_get(sk),
		};

		if (nla_put(skb, INET_DIAG_MEMINFO, sizeof(minfo), &minfo) < 0)
			goto errout;
	}

	if (ext & (1 << (INET_DIAG_SKMEMINFO - 1)))
		if (sock_diag_put_meminfo(sk, skb, INET_DIAG_SKMEMINFO))
			goto errout;

	/*
	 * RAW sockets might have user-defined protocols assigned,
	 * so report the one supplied on socket creation.
	 */
	if (sk->sk_type == SOCK_RAW) {
		if (nla_put_u8(skb, INET_DIAG_PROTOCOL, sk->sk_protocol))
			goto errout;
	}

	if (!icsk) {
		handler->idiag_get_info(sk, r, NULL);
		goto out;
	}

	icsk_pending = smp_load_acquire(&icsk->icsk_pending);
	if (icsk_pending == ICSK_TIME_RETRANS ||
	    icsk_pending == ICSK_TIME_REO_TIMEOUT ||
	    icsk_pending == ICSK_TIME_LOSS_PROBE) {
		r->idiag_timer = 1;
		r->idiag_retrans = READ_ONCE(icsk->icsk_retransmits);
		r->idiag_expires =
			jiffies_delta_to_msecs(tcp_timeout_expires(sk) - jiffies);
	} else if (icsk_pending == ICSK_TIME_PROBE0) {
		r->idiag_timer = 4;
		r->idiag_retrans = READ_ONCE(icsk->icsk_probes_out);
		r->idiag_expires =
			jiffies_delta_to_msecs(tcp_timeout_expires(sk) - jiffies);
	} else if (timer_pending(&icsk->icsk_keepalive_timer)) {
		r->idiag_timer = 2;
		r->idiag_retrans = READ_ONCE(icsk->icsk_probes_out);
		r->idiag_expires =
			jiffies_delta_to_msecs(icsk->icsk_keepalive_timer.expires - jiffies);
	}

	if ((ext & (1 << (INET_DIAG_INFO - 1))) && handler->idiag_info_size) {
		attr = nla_reserve_64bit(skb, INET_DIAG_INFO,
					 handler->idiag_info_size,
					 INET_DIAG_PAD);
		if (!attr)
			goto errout;

		info = nla_data(attr);
	}

	if (ext & (1 << (INET_DIAG_CONG - 1))) {
		int err = 0;

		rcu_read_lock();
		ca_ops = READ_ONCE(icsk->icsk_ca_ops);
		if (ca_ops)
			err = nla_put_string(skb, INET_DIAG_CONG, ca_ops->name);
		rcu_read_unlock();
		if (err < 0)
			goto errout;
	}

	handler->idiag_get_info(sk, r, info);

	if (ext & (1 << (INET_DIAG_INFO - 1)) && handler->idiag_get_aux)
		if (handler->idiag_get_aux(sk, net_admin, skb) < 0)
			goto errout;

	if (sk->sk_state < TCP_TIME_WAIT) {
		union tcp_cc_info info;
		size_t sz = 0;
		int attr;

		rcu_read_lock();
		ca_ops = READ_ONCE(icsk->icsk_ca_ops);
		if (ca_ops && ca_ops->get_info)
			sz = ca_ops->get_info(sk, ext, &attr, &info);
		rcu_read_unlock();
		if (sz && nla_put(skb, attr, sz, &info) < 0)
			goto errout;
	}

	/* Keep it at the end for potential retry with a larger skb,
	 * or else do best-effort fitting, which is only done for the
	 * first_nlmsg.
	 */
	if (cb_data->bpf_stg_diag) {
		bool first_nlmsg = ((unsigned char *)nlh == skb->data);
		unsigned int prev_min_dump_alloc;
		unsigned int total_nla_size = 0;
		unsigned int msg_len;
		int err;

		msg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
		err = bpf_sk_storage_diag_put(cb_data->bpf_stg_diag, sk, skb,
					      INET_DIAG_SK_BPF_STORAGES,
					      &total_nla_size);

		if (!err)
			goto out;

		total_nla_size += msg_len;
		prev_min_dump_alloc = cb->min_dump_alloc;
		if (total_nla_size > prev_min_dump_alloc)
			cb->min_dump_alloc = min_t(u32, total_nla_size,
						   MAX_DUMP_ALLOC_SIZE);

		if (!first_nlmsg)
			goto errout;

		if (cb->min_dump_alloc > prev_min_dump_alloc)
			/* Retry with pskb_expand_head() with
			 * __GFP_DIRECT_RECLAIM
			 */
			goto errout;

		WARN_ON_ONCE(total_nla_size <= prev_min_dump_alloc);

		/* Send what we have for this sk
		 * and move on to the next sk in the following
		 * dump()
		 */
	}

out:
	nlmsg_end(skb, nlh);
	return 0;

errout:
	nlmsg_cancel(skb, nlh);
	return -EMSGSIZE;
}
EXPORT_SYMBOL_GPL(inet_sk_diag_fill);

static int inet_diag_cmd_exact(int cmd, struct sk_buff *in_skb,
			       const struct nlmsghdr *nlh,
			       int hdrlen,
			       const struct inet_diag_req_v2 *req)
{
	const struct inet_diag_handler *handler;
	struct inet_diag_dump_data dump_data;
	int err, protocol;

	memset(&dump_data, 0, sizeof(dump_data));
	err = inet_diag_parse_attrs(nlh, hdrlen, dump_data.req_nlas);
	if (err)
		return err;

	protocol = inet_diag_get_protocol(req, &dump_data);

	handler = inet_diag_lock_handler(protocol);
	if (!handler)
		return -ENOENT;

	if (cmd == SOCK_DIAG_BY_FAMILY) {
		struct netlink_callback cb = {
			.nlh = nlh,
			.skb = in_skb,
			.data = &dump_data,
		};
		err = handler->dump_one(&cb, req);
	} else if (cmd == SOCK_DESTROY && handler->destroy) {
		err = handler->destroy(in_skb, req);
	} else {
		err = -EOPNOTSUPP;
	}
	inet_diag_unlock_handler(handler);

	return err;
}

static int bitstring_match(const __be32 *a1, const __be32 *a2, int bits)
{
	int words = bits >> 5;

	bits &= 0x1f;

	if (words) {
		if (memcmp(a1, a2, words << 2))
			return 0;
	}
	if (bits) {
		__be32 w1, w2;
		__be32 mask;

		w1 = a1[words];
		w2 = a2[words];

		mask = htonl((0xffffffff) << (32 - bits));

		if ((w1 ^ w2) & mask)
			return 0;
	}

	return 1;
}

static int inet_diag_bc_run(const struct nlattr *_bc,
			    const struct inet_diag_entry *entry)
{
	const void *bc = nla_data(_bc);
	int len = nla_len(_bc);

	while (len > 0) {
		int yes = 1;
		const struct inet_diag_bc_op *op = bc;

		switch (op->code) {
		case INET_DIAG_BC_NOP:
			break;
		case INET_DIAG_BC_JMP:
			yes = 0;
			break;
		case INET_DIAG_BC_S_EQ:
			yes = entry->sport == op[1].no;
			break;
		case INET_DIAG_BC_S_GE:
			yes = entry->sport >= op[1].no;
			break;
		case INET_DIAG_BC_S_LE:
			yes = entry->sport <= op[1].no;
			break;
		case INET_DIAG_BC_D_EQ:
			yes = entry->dport == op[1].no;
			break;
		case INET_DIAG_BC_D_GE:
			yes = entry->dport >= op[1].no;
			break;
		case INET_DIAG_BC_D_LE:
			yes = entry->dport <= op[1].no;
			break;
		case INET_DIAG_BC_AUTO:
			yes = !(entry->userlocks & SOCK_BINDPORT_LOCK);
			break;
		case INET_DIAG_BC_S_COND:
		case INET_DIAG_BC_D_COND: {
			const struct inet_diag_hostcond *cond;
			const __be32 *addr;

			cond = (const struct inet_diag_hostcond *)(op + 1);
			if (cond->port != -1 &&
			    cond->port != (op->code == INET_DIAG_BC_S_COND ?
					     entry->sport : entry->dport)) {
				yes = 0;
				break;
			}

			if (op->code == INET_DIAG_BC_S_COND)
				addr = entry->saddr;
			else
				addr = entry->daddr;

			if (cond->family != AF_UNSPEC &&
			    cond->family != entry->family) {
				if (entry->family == AF_INET6 &&
				    cond->family == AF_INET) {
					if (addr[0] == 0 && addr[1] == 0 &&
					    addr[2] == htonl(0xffff) &&
					    bitstring_match(addr + 3,
							    cond->addr,
							    cond->prefix_len))
						break;
				}
				yes = 0;
				break;
			}

			if (cond->prefix_len == 0)
				break;
			if (bitstring_match(addr, cond->addr,
					    cond->prefix_len))
				break;
			yes = 0;
			break;
		}
		case INET_DIAG_BC_DEV_COND: {
			u32 ifindex;

			ifindex = *((const u32 *)(op + 1));
			if (ifindex != entry->ifindex)
				yes = 0;
			break;
		}
		case INET_DIAG_BC_MARK_COND: {
			struct inet_diag_markcond *cond;

			cond = (struct inet_diag_markcond *)(op + 1);
			if ((entry->mark & cond->mask) != cond->mark)
				yes = 0;
			break;
		}
#ifdef CONFIG_SOCK_CGROUP_DATA
		case INET_DIAG_BC_CGROUP_COND: {
			u64 cgroup_id;

			cgroup_id = get_unaligned((const u64 *)(op + 1));
			if (cgroup_id != entry->cgroup_id)
				yes = 0;
			break;
		}
#endif
		}

		if (yes) {
			len -= op->yes;
			bc += op->yes;
		} else {
			len -= op->no;
			bc += op->no;
		}
	}
	return len == 0;
}

/* This helper is available for all sockets (ESTABLISH, TIMEWAIT, SYN_RECV)
 */
static void entry_fill_addrs(struct inet_diag_entry *entry,
			     const struct sock *sk)
{
#if IS_ENABLED(CONFIG_IPV6)
	if (entry->family == AF_INET6) {
		entry->saddr = sk->sk_v6_rcv_saddr.s6_addr32;
		entry->daddr = sk->sk_v6_daddr.s6_addr32;
	} else
#endif
	{
		entry->saddr = &sk->sk_rcv_saddr;
		entry->daddr = &sk->sk_daddr;
	}
}

int inet_diag_bc_sk(const struct inet_diag_dump_data *cb_data, struct sock *sk)
{
	const struct nlattr *bc = cb_data->inet_diag_nla_bc;
	const struct inet_sock *inet = inet_sk(sk);
	struct inet_diag_entry entry;

	if (!bc)
		return 1;

	entry.family = READ_ONCE(sk->sk_family);
	entry_fill_addrs(&entry, sk);
	entry.sport = READ_ONCE(inet->inet_num);
	entry.dport = ntohs(READ_ONCE(inet->inet_dport));
	entry.ifindex = READ_ONCE(sk->sk_bound_dev_if);
	if (cb_data->userlocks_needed)
		entry.userlocks = sk_fullsock(sk) ? READ_ONCE(sk->sk_userlocks) : 0;
	if (cb_data->mark_needed) {
		if (sk_fullsock(sk))
			entry.mark = READ_ONCE(sk->sk_mark);
		else if (sk->sk_state == TCP_NEW_SYN_RECV)
			entry.mark = inet_rsk(inet_reqsk(sk))->ir_mark;
		else if (sk->sk_state == TCP_TIME_WAIT)
			entry.mark = inet_twsk(sk)->tw_mark;
		else
			entry.mark = 0;
	}
#ifdef CONFIG_SOCK_CGROUP_DATA
	if (cb_data->cgroup_needed)
		entry.cgroup_id = sk_fullsock(sk) ?
			cgroup_id(sock_cgroup_ptr(&sk->sk_cgrp_data)) : 0;
#endif

	return inet_diag_bc_run(bc, &entry);
}
EXPORT_SYMBOL_GPL(inet_diag_bc_sk);

static int valid_cc(const void *bc, int len, int cc)
{
	while (len >= 0) {
		const struct inet_diag_bc_op *op = bc;

		if (cc > len)
			return 0;
		if (cc == len)
			return 1;
		if (op->yes < 4 || op->yes & 3)
			return 0;
		len -= op->yes;
		bc  += op->yes;
	}
	return 0;
}

/* data is u32 ifindex */
static bool valid_devcond(const struct inet_diag_bc_op *op, int len,
			  int *min_len)
{
	/* Check ifindex space. */
	*min_len += sizeof(u32);
	if (len < *min_len)
		return false;

	return true;
}
/* Validate an inet_diag_hostcond. */
static bool valid_hostcond(const struct inet_diag_bc_op *op, int len,
			   int *min_len)
{
	struct inet_diag_hostcond *cond;
	int addr_len;

	/* Check hostcond space. */
	*min_len += sizeof(struct inet_diag_hostcond);
	if (len < *min_len)
		return false;
	cond = (struct inet_diag_hostcond *)(op + 1);

	/* Check address family and address length. */
	switch (cond->family) {
	case AF_UNSPEC:
		addr_len = 0;
		break;
	case AF_INET:
		addr_len = sizeof(struct in_addr);
		break;
	case AF_INET6:
		addr_len = sizeof(struct in6_addr);
		break;
	default:
		return false;
	}
	*min_len += addr_len;
	if (len < *min_len)
		return false;

	/* Check prefix length (in bits) vs address length (in bytes). */
	if (cond->prefix_len > 8 * addr_len)
		return false;

	return true;
}

/* Validate a port comparison operator. */
static bool valid_port_comparison(const struct inet_diag_bc_op *op,
				  int len, int *min_len)
{
	/* Port comparisons put the port in a follow-on inet_diag_bc_op. */
	*min_len += sizeof(struct inet_diag_bc_op);
	if (len < *min_len)
		return false;
	return true;
}

static bool valid_markcond(const struct inet_diag_bc_op *op, int len,
			   int *min_len)
{
	*min_len += sizeof(struct inet_diag_markcond);
	return len >= *min_len;
}

#ifdef CONFIG_SOCK_CGROUP_DATA
static bool valid_cgroupcond(const struct inet_diag_bc_op *op, int len,
			     int *min_len)
{
	*min_len += sizeof(u64);
	return len >= *min_len;
}
#endif

static int inet_diag_bc_audit(struct inet_diag_dump_data *cb_data,
			      const struct sk_buff *skb)
{
	const struct nlattr *attr = cb_data->inet_diag_nla_bc;
	const void *bytecode, *bc;
	int bytecode_len, len;
	bool net_admin;

	if (!attr)
		return 0;

	if (nla_len(attr) < sizeof(struct inet_diag_bc_op))
		return -EINVAL;

	net_admin = netlink_net_capable(skb, CAP_NET_ADMIN);
	bytecode = bc = nla_data(attr);
	len = bytecode_len = nla_len(attr);

	while (len > 0) {
		int min_len = sizeof(struct inet_diag_bc_op);
		const struct inet_diag_bc_op *op = bc;

		switch (op->code) {
		case INET_DIAG_BC_S_COND:
		case INET_DIAG_BC_D_COND:
			if (!valid_hostcond(bc, len, &min_len))
				return -EINVAL;
			break;
		case INET_DIAG_BC_DEV_COND:
			if (!valid_devcond(bc, len, &min_len))
				return -EINVAL;
			break;
		case INET_DIAG_BC_S_EQ:
		case INET_DIAG_BC_S_GE:
		case INET_DIAG_BC_S_LE:
		case INET_DIAG_BC_D_EQ:
		case INET_DIAG_BC_D_GE:
		case INET_DIAG_BC_D_LE:
			if (!valid_port_comparison(bc, len, &min_len))
				return -EINVAL;
			break;
		case INET_DIAG_BC_MARK_COND:
			if (!net_admin)
				return -EPERM;
			if (!valid_markcond(bc, len, &min_len))
				return -EINVAL;
			cb_data->mark_needed = true;
			break;
#ifdef CONFIG_SOCK_CGROUP_DATA
		case INET_DIAG_BC_CGROUP_COND:
			if (!valid_cgroupcond(bc, len, &min_len))
				return -EINVAL;
			cb_data->cgroup_needed = true;
			break;
#endif
		case INET_DIAG_BC_AUTO:
			cb_data->userlocks_needed = true;
			fallthrough;
		case INET_DIAG_BC_JMP:
		case INET_DIAG_BC_NOP:
			break;
		default:
			return -EINVAL;
		}

		if (op->code != INET_DIAG_BC_NOP) {
			if (op->no < min_len || op->no > len + 4 || op->no & 3)
				return -EINVAL;
			if (op->no < len &&
			    !valid_cc(bytecode, bytecode_len, len - op->no))
				return -EINVAL;
		}

		if (op->yes < min_len || op->yes > len + 4 || op->yes & 3)
			return -EINVAL;
		bc  += op->yes;
		len -= op->yes;
	}
	return len == 0 ? 0 : -EINVAL;
}

static int __inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
			    const struct inet_diag_req_v2 *r)
{
	struct inet_diag_dump_data *cb_data = cb->data;
	const struct inet_diag_handler *handler;
	u32 prev_min_dump_alloc;
	int protocol, err = 0;

	protocol = inet_diag_get_protocol(r, cb_data);

again:
	prev_min_dump_alloc = cb->min_dump_alloc;
	handler = inet_diag_lock_handler(protocol);
	if (handler) {
		handler->dump(skb, cb, r);
		inet_diag_unlock_handler(handler);
	} else {
		err = -ENOENT;
	}
	/* The skb is not large enough to fit one sk info and
	 * inet_sk_diag_fill() has requested for a larger skb.
	 */
	if (!skb->len && cb->min_dump_alloc > prev_min_dump_alloc) {
		err = pskb_expand_head(skb, 0, cb->min_dump_alloc, GFP_KERNEL);
		if (!err)
			goto again;
	}

	return err ? : skb->len;
}

static int inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
	return __inet_diag_dump(skb, cb, nlmsg_data(cb->nlh));
}

static int __inet_diag_dump_start(struct netlink_callback *cb, int hdrlen)
{
	const struct nlmsghdr *nlh = cb->nlh;
	struct inet_diag_dump_data *cb_data;
	struct sk_buff *skb = cb->skb;
	struct nlattr *nla;
	int err;

	cb_data = kzalloc(sizeof(*cb_data), GFP_KERNEL);
	if (!cb_data)
		return -ENOMEM;

	err = inet_diag_parse_attrs(nlh, hdrlen, cb_data->req_nlas);
	if (err) {
		kfree(cb_data);
		return err;
	}
	err = inet_diag_bc_audit(cb_data, skb);
	if (err) {
		kfree(cb_data);
		return err;
	}

	nla = cb_data->inet_diag_nla_bpf_stgs;
	if (nla) {
		struct bpf_sk_storage_diag *bpf_stg_diag;

		bpf_stg_diag = bpf_sk_storage_diag_alloc(nla);
		if (IS_ERR(bpf_stg_diag)) {
			kfree(cb_data);
			return PTR_ERR(bpf_stg_diag);
		}
		cb_data->bpf_stg_diag = bpf_stg_diag;
	}

	cb->data = cb_data;
	return 0;
}

static int inet_diag_dump_start(struct netlink_callback *cb)
{
	return __inet_diag_dump_start(cb, sizeof(struct inet_diag_req_v2));
}

static int inet_diag_dump_start_compat(struct netlink_callback *cb)
{
	return __inet_diag_dump_start(cb, sizeof(struct inet_diag_req));
}

static int inet_diag_dump_done(struct netlink_callback *cb)
{
	struct inet_diag_dump_data *cb_data = cb->data;

	bpf_sk_storage_diag_free(cb_data->bpf_stg_diag);
	kfree(cb->data);

	return 0;
}

static int inet_diag_type2proto(int type)
{
	switch (type) {
	case TCPDIAG_GETSOCK:
		return IPPROTO_TCP;
	default:
		return 0;
	}
}

static int inet_diag_dump_compat(struct sk_buff *skb,
				 struct netlink_callback *cb)
{
	struct inet_diag_req *rc = nlmsg_data(cb->nlh);
	struct inet_diag_req_v2 req;

	req.sdiag_family = AF_UNSPEC; /* compatibility */
	req.sdiag_protocol = inet_diag_type2proto(cb->nlh->nlmsg_type);
	req.idiag_ext = rc->idiag_ext;
	req.pad = 0;
	req.idiag_states = rc->idiag_states;
	req.id = rc->id;

	return __inet_diag_dump(skb, cb, &req);
}

static int inet_diag_get_exact_compat(struct sk_buff *in_skb,
				      const struct nlmsghdr *nlh)
{
	struct inet_diag_req *rc = nlmsg_data(nlh);
	struct inet_diag_req_v2 req;

	req.sdiag_family = rc->idiag_family;
	req.sdiag_protocol = inet_diag_type2proto(nlh->nlmsg_type);
	req.idiag_ext = rc->idiag_ext;
	req.pad = 0;
	req.idiag_states = rc->idiag_states;
	req.id = rc->id;

	return inet_diag_cmd_exact(SOCK_DIAG_BY_FAMILY, in_skb, nlh,
				   sizeof(struct inet_diag_req), &req);
}

static int inet_diag_rcv_msg_compat(struct sk_buff *skb, struct nlmsghdr *nlh)
{
	int hdrlen = sizeof(struct inet_diag_req);
	struct net *net = sock_net(skb->sk);

	if (nlh->nlmsg_type >= INET_DIAG_GETSOCK_MAX ||
	    nlmsg_len(nlh) < hdrlen)
		return -EINVAL;

	if (nlh->nlmsg_flags & NLM_F_DUMP) {
		struct netlink_dump_control c = {
			.start = inet_diag_dump_start_compat,
			.done = inet_diag_dump_done,
			.dump = inet_diag_dump_compat,
		};
		return netlink_dump_start(net->diag_nlsk, skb, nlh, &c);
	}

	return inet_diag_get_exact_compat(skb, nlh);
}

static int inet_diag_handler_cmd(struct sk_buff *skb, struct nlmsghdr *h)
{
	int hdrlen = sizeof(struct inet_diag_req_v2);
	struct net *net = sock_net(skb->sk);

	if (nlmsg_len(h) < hdrlen)
		return -EINVAL;

	if (h->nlmsg_type == SOCK_DIAG_BY_FAMILY &&
	    h->nlmsg_flags & NLM_F_DUMP) {
		struct netlink_dump_control c = {
			.start = inet_diag_dump_start,
			.done = inet_diag_dump_done,
			.dump = inet_diag_dump,
		};
		return netlink_dump_start(net->diag_nlsk, skb, h, &c);
	}

	return inet_diag_cmd_exact(h->nlmsg_type, skb, h, hdrlen,
				   nlmsg_data(h));
}

static
int inet_diag_handler_get_info(struct sk_buff *skb, struct sock *sk)
{
	const struct inet_diag_handler *handler;
	struct nlmsghdr *nlh;
	struct nlattr *attr;
	struct inet_diag_msg *r;
	void *info = NULL;
	int err = 0;

	nlh = nlmsg_put(skb, 0, 0, SOCK_DIAG_BY_FAMILY, sizeof(*r), 0);
	if (!nlh)
		return -ENOMEM;

	r = nlmsg_data(nlh);
	memset(r, 0, sizeof(*r));
	inet_diag_msg_common_fill(r, sk);
	if (sk->sk_type == SOCK_DGRAM || sk->sk_type == SOCK_STREAM)
		r->id.idiag_sport = inet_sk(sk)->inet_sport;
	r->idiag_state = sk->sk_state;

	if ((err = nla_put_u8(skb, INET_DIAG_PROTOCOL, sk->sk_protocol))) {
		nlmsg_cancel(skb, nlh);
		return err;
	}

	handler = inet_diag_lock_handler(sk->sk_protocol);
	if (!handler) {
		nlmsg_cancel(skb, nlh);
		return -ENOENT;
	}

	attr = handler->idiag_info_size
		? nla_reserve_64bit(skb, INET_DIAG_INFO,
				    handler->idiag_info_size,
				    INET_DIAG_PAD)
		: NULL;
	if (attr)
		info = nla_data(attr);

	handler->idiag_get_info(sk, r, info);
	inet_diag_unlock_handler(handler);

	nlmsg_end(skb, nlh);
	return 0;
}

static const struct sock_diag_handler inet_diag_handler = {
	.owner = THIS_MODULE,
	.family = AF_INET,
	.dump = inet_diag_handler_cmd,
	.get_info = inet_diag_handler_get_info,
	.destroy = inet_diag_handler_cmd,
};

static const struct sock_diag_handler inet6_diag_handler = {
	.owner = THIS_MODULE,
	.family = AF_INET6,
	.dump = inet_diag_handler_cmd,
	.get_info = inet_diag_handler_get_info,
	.destroy = inet_diag_handler_cmd,
};

int inet_diag_register(const struct inet_diag_handler *h)
{
	const __u16 type = h->idiag_type;

	if (type >= IPPROTO_MAX)
		return -EINVAL;

	return !cmpxchg((const struct inet_diag_handler **)&inet_diag_table[type],
			NULL, h) ? 0 : -EEXIST;
}
EXPORT_SYMBOL_GPL(inet_diag_register);

void inet_diag_unregister(const struct inet_diag_handler *h)
{
	const __u16 type = h->idiag_type;

	if (type >= IPPROTO_MAX)
		return;

	xchg((const struct inet_diag_handler **)&inet_diag_table[type],
	     NULL);
}
EXPORT_SYMBOL_GPL(inet_diag_unregister);

static const struct sock_diag_inet_compat inet_diag_compat = {
	.owner	= THIS_MODULE,
	.fn	= inet_diag_rcv_msg_compat,
};

static int __init inet_diag_init(void)
{
	const int inet_diag_table_size = (IPPROTO_MAX *
					  sizeof(struct inet_diag_handler *));
	int err = -ENOMEM;

	inet_diag_table = kzalloc(inet_diag_table_size, GFP_KERNEL);
	if (!inet_diag_table)
		goto out;

	err = sock_diag_register(&inet_diag_handler);
	if (err)
		goto out_free_nl;

	err = sock_diag_register(&inet6_diag_handler);
	if (err)
		goto out_free_inet;

	sock_diag_register_inet_compat(&inet_diag_compat);
out:
	return err;

out_free_inet:
	sock_diag_unregister(&inet_diag_handler);
out_free_nl:
	kfree(inet_diag_table);
	goto out;
}

static void __exit inet_diag_exit(void)
{
	sock_diag_unregister(&inet6_diag_handler);
	sock_diag_unregister(&inet_diag_handler);
	sock_diag_unregister_inet_compat(&inet_diag_compat);
	kfree(inet_diag_table);
}

module_init(inet_diag_init);
module_exit(inet_diag_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("INET/INET6: socket monitoring via SOCK_DIAG");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 2 /* AF_INET */);
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 10 /* AF_INET6 */);