blob: 196fbf674dc1c9af78fe1bd74cb6eaf0a53cf993 [file] [log] [blame]
/*
* 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,
.flags = GENL_UNS_ADMIN_PERM },
};
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_rcu(group, rcu);
}
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 + nla_total_size(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");