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linux/net/psample/psample.c
Jakub Kicinski 9c5d03d362 genetlink: start to validate reserved header bytes 
We had historically not checked that genlmsghdr.reserved
is 0 on input which prevents us from using those precious
bytes in the future.

One use case would be to extend the cmd field, which is
currently just 8 bits wide and 256 is not a lot of commands
for some core families.

To make sure that new families do the right thing by default
put the onus of opting out of validation on existing families.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com> (NetLabel)
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-08-29 12:47:15 +01:00

513 lines
13 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
/*
* net/psample/psample.c - Netlink channel for packet sampling
* Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/module.h>
#include <linux/timekeeping.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>
#include <net/ip_tunnels.h>
#include <net/dst_metadata.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_bh(&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_bh(&psample_groups_lock);
cb->args[0] = idx;
return msg->len;
}
static const struct genl_small_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,
.small_ops = psample_nl_ops,
.n_small_ops = ARRAY_SIZE(psample_nl_ops),
.resv_start_op = PSAMPLE_CMD_GET_GROUP + 1,
.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_bh(&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_bh(&psample_groups_lock);
return group;
}
EXPORT_SYMBOL_GPL(psample_group_get);
void psample_group_take(struct psample_group *group)
{
spin_lock_bh(&psample_groups_lock);
group->refcount++;
spin_unlock_bh(&psample_groups_lock);
}
EXPORT_SYMBOL_GPL(psample_group_take);
void psample_group_put(struct psample_group *group)
{
spin_lock_bh(&psample_groups_lock);
if (--group->refcount == 0)
psample_group_destroy(group);
spin_unlock_bh(&psample_groups_lock);
}
EXPORT_SYMBOL_GPL(psample_group_put);
#ifdef CONFIG_INET
static int __psample_ip_tun_to_nlattr(struct sk_buff *skb,
struct ip_tunnel_info *tun_info)
{
unsigned short tun_proto = ip_tunnel_info_af(tun_info);
const void *tun_opts = ip_tunnel_info_opts(tun_info);
const struct ip_tunnel_key *tun_key = &tun_info->key;
int tun_opts_len = tun_info->options_len;
if (tun_key->tun_flags & TUNNEL_KEY &&
nla_put_be64(skb, PSAMPLE_TUNNEL_KEY_ATTR_ID, tun_key->tun_id,
PSAMPLE_TUNNEL_KEY_ATTR_PAD))
return -EMSGSIZE;
if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE &&
nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_INFO_BRIDGE))
return -EMSGSIZE;
switch (tun_proto) {
case AF_INET:
if (tun_key->u.ipv4.src &&
nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_SRC,
tun_key->u.ipv4.src))
return -EMSGSIZE;
if (tun_key->u.ipv4.dst &&
nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_DST,
tun_key->u.ipv4.dst))
return -EMSGSIZE;
break;
case AF_INET6:
if (!ipv6_addr_any(&tun_key->u.ipv6.src) &&
nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_SRC,
&tun_key->u.ipv6.src))
return -EMSGSIZE;
if (!ipv6_addr_any(&tun_key->u.ipv6.dst) &&
nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_DST,
&tun_key->u.ipv6.dst))
return -EMSGSIZE;
break;
}
if (tun_key->tos &&
nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TOS, tun_key->tos))
return -EMSGSIZE;
if (nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TTL, tun_key->ttl))
return -EMSGSIZE;
if ((tun_key->tun_flags & TUNNEL_DONT_FRAGMENT) &&
nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_DONT_FRAGMENT))
return -EMSGSIZE;
if ((tun_key->tun_flags & TUNNEL_CSUM) &&
nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_CSUM))
return -EMSGSIZE;
if (tun_key->tp_src &&
nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_SRC, tun_key->tp_src))
return -EMSGSIZE;
if (tun_key->tp_dst &&
nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_DST, tun_key->tp_dst))
return -EMSGSIZE;
if ((tun_key->tun_flags & TUNNEL_OAM) &&
nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_OAM))
return -EMSGSIZE;
if (tun_opts_len) {
if (tun_key->tun_flags & TUNNEL_GENEVE_OPT &&
nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_GENEVE_OPTS,
tun_opts_len, tun_opts))
return -EMSGSIZE;
else if (tun_key->tun_flags & TUNNEL_ERSPAN_OPT &&
nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_ERSPAN_OPTS,
tun_opts_len, tun_opts))
return -EMSGSIZE;
}
return 0;
}
static int psample_ip_tun_to_nlattr(struct sk_buff *skb,
struct ip_tunnel_info *tun_info)
{
struct nlattr *nla;
int err;
nla = nla_nest_start_noflag(skb, PSAMPLE_ATTR_TUNNEL);
if (!nla)
return -EMSGSIZE;
err = __psample_ip_tun_to_nlattr(skb, tun_info);
if (err) {
nla_nest_cancel(skb, nla);
return err;
}
nla_nest_end(skb, nla);
return 0;
}
static int psample_tunnel_meta_len(struct ip_tunnel_info *tun_info)
{
unsigned short tun_proto = ip_tunnel_info_af(tun_info);
const struct ip_tunnel_key *tun_key = &tun_info->key;
int tun_opts_len = tun_info->options_len;
int sum = nla_total_size(0); /* PSAMPLE_ATTR_TUNNEL */
if (tun_key->tun_flags & TUNNEL_KEY)
sum += nla_total_size_64bit(sizeof(u64));
if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE)
sum += nla_total_size(0);
switch (tun_proto) {
case AF_INET:
if (tun_key->u.ipv4.src)
sum += nla_total_size(sizeof(u32));
if (tun_key->u.ipv4.dst)
sum += nla_total_size(sizeof(u32));
break;
case AF_INET6:
if (!ipv6_addr_any(&tun_key->u.ipv6.src))
sum += nla_total_size(sizeof(struct in6_addr));
if (!ipv6_addr_any(&tun_key->u.ipv6.dst))
sum += nla_total_size(sizeof(struct in6_addr));
break;
}
if (tun_key->tos)
sum += nla_total_size(sizeof(u8));
sum += nla_total_size(sizeof(u8)); /* TTL */
if (tun_key->tun_flags & TUNNEL_DONT_FRAGMENT)
sum += nla_total_size(0);
if (tun_key->tun_flags & TUNNEL_CSUM)
sum += nla_total_size(0);
if (tun_key->tp_src)
sum += nla_total_size(sizeof(u16));
if (tun_key->tp_dst)
sum += nla_total_size(sizeof(u16));
if (tun_key->tun_flags & TUNNEL_OAM)
sum += nla_total_size(0);
if (tun_opts_len) {
if (tun_key->tun_flags & TUNNEL_GENEVE_OPT)
sum += nla_total_size(tun_opts_len);
else if (tun_key->tun_flags & TUNNEL_ERSPAN_OPT)
sum += nla_total_size(tun_opts_len);
}
return sum;
}
#endif
void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
u32 sample_rate, const struct psample_metadata *md)
{
ktime_t tstamp = ktime_get_real();
int out_ifindex = md->out_ifindex;
int in_ifindex = md->in_ifindex;
u32 trunc_size = md->trunc_size;
#ifdef CONFIG_INET
struct ip_tunnel_info *tun_info;
#endif
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) +
(md->out_tc_valid ? nla_total_size(sizeof(u16)) : 0) +
(md->out_tc_occ_valid ? nla_total_size_64bit(sizeof(u64)) : 0) +
(md->latency_valid ? nla_total_size_64bit(sizeof(u64)) : 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 */
nla_total_size_64bit(sizeof(u64)) + /* timestamp */
nla_total_size(sizeof(u16)); /* protocol */
#ifdef CONFIG_INET
tun_info = skb_tunnel_info(skb);
if (tun_info)
meta_len += psample_tunnel_meta_len(tun_info);
#endif
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 (md->out_tc_valid) {
ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OUT_TC, md->out_tc);
if (unlikely(ret < 0))
goto error;
}
if (md->out_tc_occ_valid) {
ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_OUT_TC_OCC,
md->out_tc_occ, PSAMPLE_ATTR_PAD);
if (unlikely(ret < 0))
goto error;
}
if (md->latency_valid) {
ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_LATENCY,
md->latency, PSAMPLE_ATTR_PAD);
if (unlikely(ret < 0))
goto error;
}
ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_TIMESTAMP,
ktime_to_ns(tstamp), PSAMPLE_ATTR_PAD);
if (unlikely(ret < 0))
goto error;
ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_PROTO,
be16_to_cpu(skb->protocol));
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;
}
#ifdef CONFIG_INET
if (tun_info) {
ret = psample_ip_tun_to_nlattr(nl_skb, tun_info);
if (unlikely(ret < 0))
goto error;
}
#endif
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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