/* * net/psample/psample.c - Netlink channel for packet sampling * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/types.h>#include <linux/kernel.h>#include <linux/skbuff.h>#include <linux/module.h>#include <net/net_namespace.h>#include <net/sock.h>#include <net/netlink.h>#include <net/genetlink.h>#include <net/psample.h>#include <linux/spinlock.h> #define PSAMPLE_MAX_PACKET_SIZE 0xffff static LIST_HEAD(psample_groups_list);static DEFINE_SPINLOCK(psample_groups_lock); /* multicast groups */enum psample_nl_multicast_groups {	PSAMPLE_NL_MCGRP_CONFIG,	PSAMPLE_NL_MCGRP_SAMPLE,}; static const struct genl_multicast_group psample_nl_mcgrps[] = {	[PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME },	[PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME },}; static struct genl_family psample_nl_family __ro_after_init; static int psample_group_nl_fill(struct sk_buff *msg,				 struct psample_group *group,				 enum psample_command cmd, u32 portid, u32 seq,				 int flags){	void *hdr;	int ret; 	hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd);	if (!hdr)		return -EMSGSIZE; 	ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);	if (ret < 0)		goto error; 	ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount);	if (ret < 0)		goto error; 	ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq);	if (ret < 0)		goto error; 	genlmsg_end(msg, hdr);	return 0; error:	genlmsg_cancel(msg, hdr);	return -EMSGSIZE;} static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg,					   struct netlink_callback *cb){	struct psample_group *group;	int start = cb->args[0];	int idx = 0;	int err; 	spin_lock(&psample_groups_lock);	list_for_each_entry(group, &psample_groups_list, list) {		if (!net_eq(group->net, sock_net(msg->sk)))			continue;		if (idx < start) {			idx++;			continue;		}		err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP,					    NETLINK_CB(cb->skb).portid,					    cb->nlh->nlmsg_seq, NLM_F_MULTI);		if (err)			break;		idx++;	} 	spin_unlock(&psample_groups_lock);	cb->args[0] = idx;	return msg->len;} static const struct genl_ops psample_nl_ops[] = {	{		.cmd = PSAMPLE_CMD_GET_GROUP,		.dumpit = psample_nl_cmd_get_group_dumpit,		/* can be retrieved by unprivileged users */	}}; static struct genl_family psample_nl_family __ro_after_init = {	.name		= PSAMPLE_GENL_NAME,	.version	= PSAMPLE_GENL_VERSION,	.maxattr	= PSAMPLE_ATTR_MAX,	.netnsok	= true,	.module		= THIS_MODULE,	.mcgrps		= psample_nl_mcgrps,	.ops		= psample_nl_ops,	.n_ops		= ARRAY_SIZE(psample_nl_ops),	.n_mcgrps	= ARRAY_SIZE(psample_nl_mcgrps),}; static void psample_group_notify(struct psample_group *group,				 enum psample_command cmd){	struct sk_buff *msg;	int err; 	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);	if (!msg)		return; 	err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI);	if (!err)		genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0,					PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC);	else		nlmsg_free(msg);} static struct psample_group *psample_group_create(struct net *net,						  u32 group_num){	struct psample_group *group; 	group = kzalloc(sizeof(*group), GFP_ATOMIC);	if (!group)		return NULL; 	group->net = net;	group->group_num = group_num;	list_add_tail(&group->list, &psample_groups_list); 	psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP);	return group;} static void psample_group_destroy(struct psample_group *group){	psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP);	list_del(&group->list);	kfree(group);} static struct psample_group *psample_group_lookup(struct net *net, u32 group_num){	struct psample_group *group; 	list_for_each_entry(group, &psample_groups_list, list)		if ((group->group_num == group_num) && (group->net == net))			return group;	return NULL;} struct psample_group *psample_group_get(struct net *net, u32 group_num){	struct psample_group *group; 	spin_lock(&psample_groups_lock); 	group = psample_group_lookup(net, group_num);	if (!group) {		group = psample_group_create(net, group_num);		if (!group)			goto out;	}	group->refcount++; out:	spin_unlock(&psample_groups_lock);	return group;}EXPORT_SYMBOL_GPL(psample_group_get); void psample_group_put(struct psample_group *group){	spin_lock(&psample_groups_lock); 	if (--group->refcount == 0)		psample_group_destroy(group); 	spin_unlock(&psample_groups_lock);}EXPORT_SYMBOL_GPL(psample_group_put); void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,			   u32 trunc_size, int in_ifindex, int out_ifindex,			   u32 sample_rate){	struct sk_buff *nl_skb;	int data_len;	int meta_len;	void *data;	int ret; 	meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) +		   (out_ifindex ? nla_total_size(sizeof(u16)) : 0) +		   nla_total_size(sizeof(u32)) +	/* sample_rate */		   nla_total_size(sizeof(u32)) +	/* orig_size */		   nla_total_size(sizeof(u32)) +	/* group_num */		   nla_total_size(sizeof(u32));		/* seq */ 	data_len = min(skb->len, trunc_size);	if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE)		data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN			    - NLA_ALIGNTO; 	nl_skb = genlmsg_new(meta_len + data_len, GFP_ATOMIC);	if (unlikely(!nl_skb))		return; 	data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0,			   PSAMPLE_CMD_SAMPLE);	if (unlikely(!data))		goto error; 	if (in_ifindex) {		ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex);		if (unlikely(ret < 0))			goto error;	} 	if (out_ifindex) {		ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex);		if (unlikely(ret < 0))			goto error;	} 	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate);	if (unlikely(ret < 0))		goto error; 	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len);	if (unlikely(ret < 0))		goto error; 	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);	if (unlikely(ret < 0))		goto error; 	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++);	if (unlikely(ret < 0))		goto error; 	if (data_len) {		int nla_len = nla_total_size(data_len);		struct nlattr *nla; 		nla = skb_put(nl_skb, nla_len);		nla->nla_type = PSAMPLE_ATTR_DATA;		nla->nla_len = nla_attr_size(data_len); 		if (skb_copy_bits(skb, 0, nla_data(nla), data_len))			goto error;	} 	genlmsg_end(nl_skb, data);	genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0,				PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC); 	return;error:	pr_err_ratelimited("Could not create psample log message\n");	nlmsg_free(nl_skb);}EXPORT_SYMBOL_GPL(psample_sample_packet); static int __init psample_module_init(void){	return genl_register_family(&psample_nl_family);} static void __exit psample_module_exit(void){	genl_unregister_family(&psample_nl_family);} module_init(psample_module_init);module_exit(psample_module_exit); MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");MODULE_DESCRIPTION("netlink channel for packet sampling");MODULE_LICENSE("GPL v2");