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linux/net/sched/cls_flow.c
WANG Cong 763dbf6328 net_sched: move the empty tp check from ->destroy() to ->delete() 
We could have a race condition where in ->classify() path we
dereference tp->root and meanwhile a parallel ->destroy() makes it
a NULL. Daniel cured this bug in commit d936377414
("net, sched: respect rcu grace period on cls destruction").

This happens when ->destroy() is called for deleting a filter to
check if we are the last one in tp, this tp is still linked and
visible at that time. The root cause of this problem is the semantic
of ->destroy(), it does two things (for non-force case):

1) check if tp is empty
2) if tp is empty we could really destroy it

and its caller, if cares, needs to check its return value to see if it
is really destroyed. Therefore we can't unlink tp unless we know it is
empty.

As suggested by Daniel, we could actually move the test logic to ->delete()
so that we can safely unlink tp after ->delete() tells us the last one is
just deleted and before ->destroy().

Fixes: 1e052be69d ("net_sched: destroy proto tp when all filters are gone")
Cc: Roi Dayan <roid@mellanox.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-21 13:58:15 -04:00

718 lines
16 KiB
C
Raw Blame History

/*
* net/sched/cls_flow.c Generic flow classifier
*
* Copyright (c) 2007, 2008 Patrick McHardy <kaber@trash.net>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*/
#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_head rcu;
};
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) tc_skb_protocol(skb);
}
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) tc_skb_protocol(skb);
}
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 (tc_skb_protocol(skb)) {
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 (tc_skb_protocol(skb)) {
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(unsigned long arg)
{
struct flow_filter *f = (struct flow_filter *)arg;
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 rcu_head *head)
{
struct flow_filter *f = container_of(head, struct flow_filter, rcu);
del_timer_sync(&f->perturb_timer);
tcf_exts_destroy(&f->exts);
tcf_em_tree_destroy(&f->ematches);
kfree(f);
}
static int flow_change(struct net *net, struct sk_buff *in_skb,
struct tcf_proto *tp, unsigned long base,
u32 handle, struct nlattr **tca,
unsigned long *arg, bool ovr)
{
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];
struct tcf_exts e;
struct tcf_ematch_tree t;
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(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;
}
err = tcf_exts_init(&e, TCA_FLOW_ACT, TCA_FLOW_POLICE);
if (err < 0)
goto err1;
err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr);
if (err < 0)
goto err1;
err = tcf_em_tree_validate(tp, tb[TCA_FLOW_EMATCHES], &t);
if (err < 0)
goto err1;
err = -ENOBUFS;
fnew = kzalloc(sizeof(*fnew), GFP_KERNEL);
if (!fnew)
goto err2;
err = tcf_exts_init(&fnew->exts, TCA_FLOW_ACT, TCA_FLOW_POLICE);
if (err < 0)
goto err3;
fold = (struct flow_filter *)*arg;
if (fold) {
err = -EINVAL;
if (fold->handle != handle && handle)
goto err3;
/* 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 err3;
if (mode == FLOW_MODE_HASH)
perturb_period = fold->perturb_period;
if (tb[TCA_FLOW_PERTURB]) {
if (mode != FLOW_MODE_HASH)
goto err3;
perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
}
} else {
err = -EINVAL;
if (!handle)
goto err3;
if (!tb[TCA_FLOW_KEYS])
goto err3;
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 err3;
if (tb[TCA_FLOW_PERTURB]) {
if (mode != FLOW_MODE_HASH)
goto err3;
perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
}
if (TC_H_MAJ(baseclass) == 0)
baseclass = TC_H_MAKE(tp->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);
}
setup_deferrable_timer(&fnew->perturb_timer, flow_perturbation,
(unsigned long)fnew);
tcf_exts_change(tp, &fnew->exts, &e);
tcf_em_tree_change(tp, &fnew->ematches, &t);
netif_keep_dst(qdisc_dev(tp->q));
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 == 0)
list_add_tail_rcu(&fnew->list, &head->filters);
else
list_replace_rcu(&fold->list, &fnew->list);
*arg = (unsigned long)fnew;
if (fold)
call_rcu(&fold->rcu, flow_destroy_filter);
return 0;
err3:
tcf_exts_destroy(&fnew->exts);
err2:
tcf_em_tree_destroy(&t);
kfree(fnew);
err1:
tcf_exts_destroy(&e);
return err;
}
static int flow_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
{
struct flow_head *head = rtnl_dereference(tp->root);
struct flow_filter *f = (struct flow_filter *)arg;
list_del_rcu(&f->list);
call_rcu(&f->rcu, flow_destroy_filter);
*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)
{
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);
call_rcu(&f->rcu, flow_destroy_filter);
}
kfree_rcu(head, rcu);
}
static unsigned long 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 (unsigned long)f;
return 0;
}
static int flow_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
struct sk_buff *skb, struct tcmsg *t)
{
struct flow_filter *f = (struct flow_filter *)fh;
struct nlattr *nest;
if (f == NULL)
return skb->len;
t->tcm_handle = f->handle;
nest = nla_nest_start(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)
{
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, (unsigned long)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");
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