linux/net/sched/cls_flow.c
Toke Høiland-Jørgensen d7bf2ebebc sched: consistently handle layer3 header accesses in the presence of VLANs
There are a couple of places in net/sched/ that check skb->protocol and act
on the value there. However, in the presence of VLAN tags, the value stored
in skb->protocol can be inconsistent based on whether VLAN acceleration is
enabled. The commit quoted in the Fixes tag below fixed the users of
skb->protocol to use a helper that will always see the VLAN ethertype.

However, most of the callers don't actually handle the VLAN ethertype, but
expect to find the IP header type in the protocol field. This means that
things like changing the ECN field, or parsing diffserv values, stops
working if there's a VLAN tag, or if there are multiple nested VLAN
tags (QinQ).

To fix this, change the helper to take an argument that indicates whether
the caller wants to skip the VLAN tags or not. When skipping VLAN tags, we
make sure to skip all of them, so behaviour is consistent even in QinQ
mode.

To make the helper usable from the ECN code, move it to if_vlan.h instead
of pkt_sched.h.

v3:
- Remove empty lines
- Move vlan variable definitions inside loop in skb_protocol()
- Also use skb_protocol() helper in IP{,6}_ECN_decapsulate() and
  bpf_skb_ecn_set_ce()

v2:
- Use eth_type_vlan() helper in skb_protocol()
- Also fix code that reads skb->protocol directly
- Change a couple of 'if/else if' statements to switch constructs to avoid
  calling the helper twice

Reported-by: Ilya Ponetayev <i.ponetaev@ndmsystems.com>
Fixes: d8b9605d26 ("net: sched: fix skb->protocol use in case of accelerated vlan path")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-07-03 14:34:53 -07:00

726 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/sched/cls_flow.c Generic flow classifier
*
* Copyright (c) 2007, 2008 Patrick McHardy <kaber@trash.net>
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/jhash.h>
#include <linux/random.h>
#include <linux/pkt_cls.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/if_vlan.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <net/inet_sock.h>
#include <net/pkt_cls.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/flow_dissector.h>
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <net/netfilter/nf_conntrack.h>
#endif
struct flow_head {
struct list_head filters;
struct rcu_head rcu;
};
struct flow_filter {
struct list_head list;
struct tcf_exts exts;
struct tcf_ematch_tree ematches;
struct tcf_proto *tp;
struct timer_list perturb_timer;
u32 perturb_period;
u32 handle;
u32 nkeys;
u32 keymask;
u32 mode;
u32 mask;
u32 xor;
u32 rshift;
u32 addend;
u32 divisor;
u32 baseclass;
u32 hashrnd;
struct rcu_work rwork;
};
static inline u32 addr_fold(void *addr)
{
unsigned long a = (unsigned long)addr;
return (a & 0xFFFFFFFF) ^ (BITS_PER_LONG > 32 ? a >> 32 : 0);
}
static u32 flow_get_src(const struct sk_buff *skb, const struct flow_keys *flow)
{
__be32 src = flow_get_u32_src(flow);
if (src)
return ntohl(src);
return addr_fold(skb->sk);
}
static u32 flow_get_dst(const struct sk_buff *skb, const struct flow_keys *flow)
{
__be32 dst = flow_get_u32_dst(flow);
if (dst)
return ntohl(dst);
return addr_fold(skb_dst(skb)) ^ (__force u16)skb_protocol(skb, true);
}
static u32 flow_get_proto(const struct sk_buff *skb,
const struct flow_keys *flow)
{
return flow->basic.ip_proto;
}
static u32 flow_get_proto_src(const struct sk_buff *skb,
const struct flow_keys *flow)
{
if (flow->ports.ports)
return ntohs(flow->ports.src);
return addr_fold(skb->sk);
}
static u32 flow_get_proto_dst(const struct sk_buff *skb,
const struct flow_keys *flow)
{
if (flow->ports.ports)
return ntohs(flow->ports.dst);
return addr_fold(skb_dst(skb)) ^ (__force u16)skb_protocol(skb, true);
}
static u32 flow_get_iif(const struct sk_buff *skb)
{
return skb->skb_iif;
}
static u32 flow_get_priority(const struct sk_buff *skb)
{
return skb->priority;
}
static u32 flow_get_mark(const struct sk_buff *skb)
{
return skb->mark;
}
static u32 flow_get_nfct(const struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
return addr_fold(skb_nfct(skb));
#else
return 0;
#endif
}
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#define CTTUPLE(skb, member) \
({ \
enum ip_conntrack_info ctinfo; \
const struct nf_conn *ct = nf_ct_get(skb, &ctinfo); \
if (ct == NULL) \
goto fallback; \
ct->tuplehash[CTINFO2DIR(ctinfo)].tuple.member; \
})
#else
#define CTTUPLE(skb, member) \
({ \
goto fallback; \
0; \
})
#endif
static u32 flow_get_nfct_src(const struct sk_buff *skb,
const struct flow_keys *flow)
{
switch (skb_protocol(skb, true)) {
case htons(ETH_P_IP):
return ntohl(CTTUPLE(skb, src.u3.ip));
case htons(ETH_P_IPV6):
return ntohl(CTTUPLE(skb, src.u3.ip6[3]));
}
fallback:
return flow_get_src(skb, flow);
}
static u32 flow_get_nfct_dst(const struct sk_buff *skb,
const struct flow_keys *flow)
{
switch (skb_protocol(skb, true)) {
case htons(ETH_P_IP):
return ntohl(CTTUPLE(skb, dst.u3.ip));
case htons(ETH_P_IPV6):
return ntohl(CTTUPLE(skb, dst.u3.ip6[3]));
}
fallback:
return flow_get_dst(skb, flow);
}
static u32 flow_get_nfct_proto_src(const struct sk_buff *skb,
const struct flow_keys *flow)
{
return ntohs(CTTUPLE(skb, src.u.all));
fallback:
return flow_get_proto_src(skb, flow);
}
static u32 flow_get_nfct_proto_dst(const struct sk_buff *skb,
const struct flow_keys *flow)
{
return ntohs(CTTUPLE(skb, dst.u.all));
fallback:
return flow_get_proto_dst(skb, flow);
}
static u32 flow_get_rtclassid(const struct sk_buff *skb)
{
#ifdef CONFIG_IP_ROUTE_CLASSID
if (skb_dst(skb))
return skb_dst(skb)->tclassid;
#endif
return 0;
}
static u32 flow_get_skuid(const struct sk_buff *skb)
{
struct sock *sk = skb_to_full_sk(skb);
if (sk && sk->sk_socket && sk->sk_socket->file) {
kuid_t skuid = sk->sk_socket->file->f_cred->fsuid;
return from_kuid(&init_user_ns, skuid);
}
return 0;
}
static u32 flow_get_skgid(const struct sk_buff *skb)
{
struct sock *sk = skb_to_full_sk(skb);
if (sk && sk->sk_socket && sk->sk_socket->file) {
kgid_t skgid = sk->sk_socket->file->f_cred->fsgid;
return from_kgid(&init_user_ns, skgid);
}
return 0;
}
static u32 flow_get_vlan_tag(const struct sk_buff *skb)
{
u16 uninitialized_var(tag);
if (vlan_get_tag(skb, &tag) < 0)
return 0;
return tag & VLAN_VID_MASK;
}
static u32 flow_get_rxhash(struct sk_buff *skb)
{
return skb_get_hash(skb);
}
static u32 flow_key_get(struct sk_buff *skb, int key, struct flow_keys *flow)
{
switch (key) {
case FLOW_KEY_SRC:
return flow_get_src(skb, flow);
case FLOW_KEY_DST:
return flow_get_dst(skb, flow);
case FLOW_KEY_PROTO:
return flow_get_proto(skb, flow);
case FLOW_KEY_PROTO_SRC:
return flow_get_proto_src(skb, flow);
case FLOW_KEY_PROTO_DST:
return flow_get_proto_dst(skb, flow);
case FLOW_KEY_IIF:
return flow_get_iif(skb);
case FLOW_KEY_PRIORITY:
return flow_get_priority(skb);
case FLOW_KEY_MARK:
return flow_get_mark(skb);
case FLOW_KEY_NFCT:
return flow_get_nfct(skb);
case FLOW_KEY_NFCT_SRC:
return flow_get_nfct_src(skb, flow);
case FLOW_KEY_NFCT_DST:
return flow_get_nfct_dst(skb, flow);
case FLOW_KEY_NFCT_PROTO_SRC:
return flow_get_nfct_proto_src(skb, flow);
case FLOW_KEY_NFCT_PROTO_DST:
return flow_get_nfct_proto_dst(skb, flow);
case FLOW_KEY_RTCLASSID:
return flow_get_rtclassid(skb);
case FLOW_KEY_SKUID:
return flow_get_skuid(skb);
case FLOW_KEY_SKGID:
return flow_get_skgid(skb);
case FLOW_KEY_VLAN_TAG:
return flow_get_vlan_tag(skb);
case FLOW_KEY_RXHASH:
return flow_get_rxhash(skb);
default:
WARN_ON(1);
return 0;
}
}
#define FLOW_KEYS_NEEDED ((1 << FLOW_KEY_SRC) | \
(1 << FLOW_KEY_DST) | \
(1 << FLOW_KEY_PROTO) | \
(1 << FLOW_KEY_PROTO_SRC) | \
(1 << FLOW_KEY_PROTO_DST) | \
(1 << FLOW_KEY_NFCT_SRC) | \
(1 << FLOW_KEY_NFCT_DST) | \
(1 << FLOW_KEY_NFCT_PROTO_SRC) | \
(1 << FLOW_KEY_NFCT_PROTO_DST))
static int flow_classify(struct sk_buff *skb, const struct tcf_proto *tp,
struct tcf_result *res)
{
struct flow_head *head = rcu_dereference_bh(tp->root);
struct flow_filter *f;
u32 keymask;
u32 classid;
unsigned int n, key;
int r;
list_for_each_entry_rcu(f, &head->filters, list) {
u32 keys[FLOW_KEY_MAX + 1];
struct flow_keys flow_keys;
if (!tcf_em_tree_match(skb, &f->ematches, NULL))
continue;
keymask = f->keymask;
if (keymask & FLOW_KEYS_NEEDED)
skb_flow_dissect_flow_keys(skb, &flow_keys, 0);
for (n = 0; n < f->nkeys; n++) {
key = ffs(keymask) - 1;
keymask &= ~(1 << key);
keys[n] = flow_key_get(skb, key, &flow_keys);
}
if (f->mode == FLOW_MODE_HASH)
classid = jhash2(keys, f->nkeys, f->hashrnd);
else {
classid = keys[0];
classid = (classid & f->mask) ^ f->xor;
classid = (classid >> f->rshift) + f->addend;
}
if (f->divisor)
classid %= f->divisor;
res->class = 0;
res->classid = TC_H_MAKE(f->baseclass, f->baseclass + classid);
r = tcf_exts_exec(skb, &f->exts, res);
if (r < 0)
continue;
return r;
}
return -1;
}
static void flow_perturbation(struct timer_list *t)
{
struct flow_filter *f = from_timer(f, t, perturb_timer);
get_random_bytes(&f->hashrnd, 4);
if (f->perturb_period)
mod_timer(&f->perturb_timer, jiffies + f->perturb_period);
}
static const struct nla_policy flow_policy[TCA_FLOW_MAX + 1] = {
[TCA_FLOW_KEYS] = { .type = NLA_U32 },
[TCA_FLOW_MODE] = { .type = NLA_U32 },
[TCA_FLOW_BASECLASS] = { .type = NLA_U32 },
[TCA_FLOW_RSHIFT] = { .type = NLA_U32 },
[TCA_FLOW_ADDEND] = { .type = NLA_U32 },
[TCA_FLOW_MASK] = { .type = NLA_U32 },
[TCA_FLOW_XOR] = { .type = NLA_U32 },
[TCA_FLOW_DIVISOR] = { .type = NLA_U32 },
[TCA_FLOW_ACT] = { .type = NLA_NESTED },
[TCA_FLOW_POLICE] = { .type = NLA_NESTED },
[TCA_FLOW_EMATCHES] = { .type = NLA_NESTED },
[TCA_FLOW_PERTURB] = { .type = NLA_U32 },
};
static void __flow_destroy_filter(struct flow_filter *f)
{
del_timer_sync(&f->perturb_timer);
tcf_exts_destroy(&f->exts);
tcf_em_tree_destroy(&f->ematches);
tcf_exts_put_net(&f->exts);
kfree(f);
}
static void flow_destroy_filter_work(struct work_struct *work)
{
struct flow_filter *f = container_of(to_rcu_work(work),
struct flow_filter,
rwork);
rtnl_lock();
__flow_destroy_filter(f);
rtnl_unlock();
}
static int flow_change(struct net *net, struct sk_buff *in_skb,
struct tcf_proto *tp, unsigned long base,
u32 handle, struct nlattr **tca,
void **arg, bool ovr, bool rtnl_held,
struct netlink_ext_ack *extack)
{
struct flow_head *head = rtnl_dereference(tp->root);
struct flow_filter *fold, *fnew;
struct nlattr *opt = tca[TCA_OPTIONS];
struct nlattr *tb[TCA_FLOW_MAX + 1];
unsigned int nkeys = 0;
unsigned int perturb_period = 0;
u32 baseclass = 0;
u32 keymask = 0;
u32 mode;
int err;
if (opt == NULL)
return -EINVAL;
err = nla_parse_nested_deprecated(tb, TCA_FLOW_MAX, opt, flow_policy,
NULL);
if (err < 0)
return err;
if (tb[TCA_FLOW_BASECLASS]) {
baseclass = nla_get_u32(tb[TCA_FLOW_BASECLASS]);
if (TC_H_MIN(baseclass) == 0)
return -EINVAL;
}
if (tb[TCA_FLOW_KEYS]) {
keymask = nla_get_u32(tb[TCA_FLOW_KEYS]);
nkeys = hweight32(keymask);
if (nkeys == 0)
return -EINVAL;
if (fls(keymask) - 1 > FLOW_KEY_MAX)
return -EOPNOTSUPP;
if ((keymask & (FLOW_KEY_SKUID|FLOW_KEY_SKGID)) &&
sk_user_ns(NETLINK_CB(in_skb).sk) != &init_user_ns)
return -EOPNOTSUPP;
}
fnew = kzalloc(sizeof(*fnew), GFP_KERNEL);
if (!fnew)
return -ENOBUFS;
err = tcf_em_tree_validate(tp, tb[TCA_FLOW_EMATCHES], &fnew->ematches);
if (err < 0)
goto err1;
err = tcf_exts_init(&fnew->exts, net, TCA_FLOW_ACT, TCA_FLOW_POLICE);
if (err < 0)
goto err2;
err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &fnew->exts, ovr,
true, extack);
if (err < 0)
goto err2;
fold = *arg;
if (fold) {
err = -EINVAL;
if (fold->handle != handle && handle)
goto err2;
/* Copy fold into fnew */
fnew->tp = fold->tp;
fnew->handle = fold->handle;
fnew->nkeys = fold->nkeys;
fnew->keymask = fold->keymask;
fnew->mode = fold->mode;
fnew->mask = fold->mask;
fnew->xor = fold->xor;
fnew->rshift = fold->rshift;
fnew->addend = fold->addend;
fnew->divisor = fold->divisor;
fnew->baseclass = fold->baseclass;
fnew->hashrnd = fold->hashrnd;
mode = fold->mode;
if (tb[TCA_FLOW_MODE])
mode = nla_get_u32(tb[TCA_FLOW_MODE]);
if (mode != FLOW_MODE_HASH && nkeys > 1)
goto err2;
if (mode == FLOW_MODE_HASH)
perturb_period = fold->perturb_period;
if (tb[TCA_FLOW_PERTURB]) {
if (mode != FLOW_MODE_HASH)
goto err2;
perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
}
} else {
err = -EINVAL;
if (!handle)
goto err2;
if (!tb[TCA_FLOW_KEYS])
goto err2;
mode = FLOW_MODE_MAP;
if (tb[TCA_FLOW_MODE])
mode = nla_get_u32(tb[TCA_FLOW_MODE]);
if (mode != FLOW_MODE_HASH && nkeys > 1)
goto err2;
if (tb[TCA_FLOW_PERTURB]) {
if (mode != FLOW_MODE_HASH)
goto err2;
perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
}
if (TC_H_MAJ(baseclass) == 0) {
struct Qdisc *q = tcf_block_q(tp->chain->block);
baseclass = TC_H_MAKE(q->handle, baseclass);
}
if (TC_H_MIN(baseclass) == 0)
baseclass = TC_H_MAKE(baseclass, 1);
fnew->handle = handle;
fnew->mask = ~0U;
fnew->tp = tp;
get_random_bytes(&fnew->hashrnd, 4);
}
timer_setup(&fnew->perturb_timer, flow_perturbation, TIMER_DEFERRABLE);
tcf_block_netif_keep_dst(tp->chain->block);
if (tb[TCA_FLOW_KEYS]) {
fnew->keymask = keymask;
fnew->nkeys = nkeys;
}
fnew->mode = mode;
if (tb[TCA_FLOW_MASK])
fnew->mask = nla_get_u32(tb[TCA_FLOW_MASK]);
if (tb[TCA_FLOW_XOR])
fnew->xor = nla_get_u32(tb[TCA_FLOW_XOR]);
if (tb[TCA_FLOW_RSHIFT])
fnew->rshift = nla_get_u32(tb[TCA_FLOW_RSHIFT]);
if (tb[TCA_FLOW_ADDEND])
fnew->addend = nla_get_u32(tb[TCA_FLOW_ADDEND]);
if (tb[TCA_FLOW_DIVISOR])
fnew->divisor = nla_get_u32(tb[TCA_FLOW_DIVISOR]);
if (baseclass)
fnew->baseclass = baseclass;
fnew->perturb_period = perturb_period;
if (perturb_period)
mod_timer(&fnew->perturb_timer, jiffies + perturb_period);
if (!*arg)
list_add_tail_rcu(&fnew->list, &head->filters);
else
list_replace_rcu(&fold->list, &fnew->list);
*arg = fnew;
if (fold) {
tcf_exts_get_net(&fold->exts);
tcf_queue_work(&fold->rwork, flow_destroy_filter_work);
}
return 0;
err2:
tcf_exts_destroy(&fnew->exts);
tcf_em_tree_destroy(&fnew->ematches);
err1:
kfree(fnew);
return err;
}
static int flow_delete(struct tcf_proto *tp, void *arg, bool *last,
bool rtnl_held, struct netlink_ext_ack *extack)
{
struct flow_head *head = rtnl_dereference(tp->root);
struct flow_filter *f = arg;
list_del_rcu(&f->list);
tcf_exts_get_net(&f->exts);
tcf_queue_work(&f->rwork, flow_destroy_filter_work);
*last = list_empty(&head->filters);
return 0;
}
static int flow_init(struct tcf_proto *tp)
{
struct flow_head *head;
head = kzalloc(sizeof(*head), GFP_KERNEL);
if (head == NULL)
return -ENOBUFS;
INIT_LIST_HEAD(&head->filters);
rcu_assign_pointer(tp->root, head);
return 0;
}
static void flow_destroy(struct tcf_proto *tp, bool rtnl_held,
struct netlink_ext_ack *extack)
{
struct flow_head *head = rtnl_dereference(tp->root);
struct flow_filter *f, *next;
list_for_each_entry_safe(f, next, &head->filters, list) {
list_del_rcu(&f->list);
if (tcf_exts_get_net(&f->exts))
tcf_queue_work(&f->rwork, flow_destroy_filter_work);
else
__flow_destroy_filter(f);
}
kfree_rcu(head, rcu);
}
static void *flow_get(struct tcf_proto *tp, u32 handle)
{
struct flow_head *head = rtnl_dereference(tp->root);
struct flow_filter *f;
list_for_each_entry(f, &head->filters, list)
if (f->handle == handle)
return f;
return NULL;
}
static int flow_dump(struct net *net, struct tcf_proto *tp, void *fh,
struct sk_buff *skb, struct tcmsg *t, bool rtnl_held)
{
struct flow_filter *f = fh;
struct nlattr *nest;
if (f == NULL)
return skb->len;
t->tcm_handle = f->handle;
nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
if (nest == NULL)
goto nla_put_failure;
if (nla_put_u32(skb, TCA_FLOW_KEYS, f->keymask) ||
nla_put_u32(skb, TCA_FLOW_MODE, f->mode))
goto nla_put_failure;
if (f->mask != ~0 || f->xor != 0) {
if (nla_put_u32(skb, TCA_FLOW_MASK, f->mask) ||
nla_put_u32(skb, TCA_FLOW_XOR, f->xor))
goto nla_put_failure;
}
if (f->rshift &&
nla_put_u32(skb, TCA_FLOW_RSHIFT, f->rshift))
goto nla_put_failure;
if (f->addend &&
nla_put_u32(skb, TCA_FLOW_ADDEND, f->addend))
goto nla_put_failure;
if (f->divisor &&
nla_put_u32(skb, TCA_FLOW_DIVISOR, f->divisor))
goto nla_put_failure;
if (f->baseclass &&
nla_put_u32(skb, TCA_FLOW_BASECLASS, f->baseclass))
goto nla_put_failure;
if (f->perturb_period &&
nla_put_u32(skb, TCA_FLOW_PERTURB, f->perturb_period / HZ))
goto nla_put_failure;
if (tcf_exts_dump(skb, &f->exts) < 0)
goto nla_put_failure;
#ifdef CONFIG_NET_EMATCH
if (f->ematches.hdr.nmatches &&
tcf_em_tree_dump(skb, &f->ematches, TCA_FLOW_EMATCHES) < 0)
goto nla_put_failure;
#endif
nla_nest_end(skb, nest);
if (tcf_exts_dump_stats(skb, &f->exts) < 0)
goto nla_put_failure;
return skb->len;
nla_put_failure:
nla_nest_cancel(skb, nest);
return -1;
}
static void flow_walk(struct tcf_proto *tp, struct tcf_walker *arg,
bool rtnl_held)
{
struct flow_head *head = rtnl_dereference(tp->root);
struct flow_filter *f;
list_for_each_entry(f, &head->filters, list) {
if (arg->count < arg->skip)
goto skip;
if (arg->fn(tp, f, arg) < 0) {
arg->stop = 1;
break;
}
skip:
arg->count++;
}
}
static struct tcf_proto_ops cls_flow_ops __read_mostly = {
.kind = "flow",
.classify = flow_classify,
.init = flow_init,
.destroy = flow_destroy,
.change = flow_change,
.delete = flow_delete,
.get = flow_get,
.dump = flow_dump,
.walk = flow_walk,
.owner = THIS_MODULE,
};
static int __init cls_flow_init(void)
{
return register_tcf_proto_ops(&cls_flow_ops);
}
static void __exit cls_flow_exit(void)
{
unregister_tcf_proto_ops(&cls_flow_ops);
}
module_init(cls_flow_init);
module_exit(cls_flow_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_DESCRIPTION("TC flow classifier");