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kernel-ark/net/psample/psample.c
Johannes Berg ef6243acb4 genetlink: optionally validate strictly/dumps 
Add options to strictly validate messages and dump messages,
sometimes perhaps validating dump messages non-strictly may
be required, so add an option for that as well.

Since none of this can really be applied to existing commands,
set the options everwhere using the following spatch:

    @@
    identifier ops;
    expression X;
    @@
    struct genl_ops ops[] = {
    ...,
     {
            .cmd = X,
    +       .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
            ...
     },
    ...
    };

For new commands one should just not copy the .validate 'opt-out'
flags and thus get strict validation.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-27 17:07:22 -04:00

303 lines
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/*
* 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,
.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
.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");
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