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alistair23-linux/net/sched/act_csum.c
Dmytro Linkin 7be8ef2cdb net: sched: use temporary variable for actions indexes 
Currently init call of all actions (except ipt) init their 'parm'
structure as a direct pointer to nla data in skb. This leads to race
condition when some of the filter actions were initialized successfully
(and were assigned with idr action index that was written directly
into nla data), but then were deleted and retried (due to following
action module missing or classifier-initiated retry), in which case
action init code tries to insert action to idr with index that was
assigned on previous iteration. During retry the index can be reused
by another action that was inserted concurrently, which causes
unintended action sharing between filters.
To fix described race condition, save action idr index to temporary
stack-allocated variable instead on nla data.

Fixes: 0190c1d452 ("net: sched: atomically check-allocate action")
Signed-off-by: Dmytro Linkin <dmitrolin@mellanox.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-08-05 10:59:14 -07:00

747 lines
17 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Checksum updating actions
*
* Copyright (c) 2010 Gregoire Baron <baronchon@n7mm.org>
*/
#include <linux/types.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/netlink.h>
#include <net/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/icmp.h>
#include <linux/icmpv6.h>
#include <linux/igmp.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/ip6_checksum.h>
#include <net/sctp/checksum.h>
#include <net/act_api.h>
#include <net/pkt_cls.h>
#include <linux/tc_act/tc_csum.h>
#include <net/tc_act/tc_csum.h>
static const struct nla_policy csum_policy[TCA_CSUM_MAX + 1] = {
[TCA_CSUM_PARMS] = { .len = sizeof(struct tc_csum), },
};
static unsigned int csum_net_id;
static struct tc_action_ops act_csum_ops;
static int tcf_csum_init(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action **a, int ovr,
int bind, bool rtnl_held, struct tcf_proto *tp,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, csum_net_id);
struct tcf_csum_params *params_new;
struct nlattr *tb[TCA_CSUM_MAX + 1];
struct tcf_chain *goto_ch = NULL;
struct tc_csum *parm;
struct tcf_csum *p;
int ret = 0, err;
u32 index;
if (nla == NULL)
return -EINVAL;
err = nla_parse_nested_deprecated(tb, TCA_CSUM_MAX, nla, csum_policy,
NULL);
if (err < 0)
return err;
if (tb[TCA_CSUM_PARMS] == NULL)
return -EINVAL;
parm = nla_data(tb[TCA_CSUM_PARMS]);
index = parm->index;
err = tcf_idr_check_alloc(tn, &index, a, bind);
if (!err) {
ret = tcf_idr_create(tn, index, est, a,
&act_csum_ops, bind, true);
if (ret) {
tcf_idr_cleanup(tn, index);
return ret;
}
ret = ACT_P_CREATED;
} else if (err > 0) {
if (bind)/* dont override defaults */
return 0;
if (!ovr) {
tcf_idr_release(*a, bind);
return -EEXIST;
}
} else {
return err;
}
err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
if (err < 0)
goto release_idr;
p = to_tcf_csum(*a);
params_new = kzalloc(sizeof(*params_new), GFP_KERNEL);
if (unlikely(!params_new)) {
err = -ENOMEM;
goto put_chain;
}
params_new->update_flags = parm->update_flags;
spin_lock_bh(&p->tcf_lock);
goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
rcu_swap_protected(p->params, params_new,
lockdep_is_held(&p->tcf_lock));
spin_unlock_bh(&p->tcf_lock);
if (goto_ch)
tcf_chain_put_by_act(goto_ch);
if (params_new)
kfree_rcu(params_new, rcu);
if (ret == ACT_P_CREATED)
tcf_idr_insert(tn, *a);
return ret;
put_chain:
if (goto_ch)
tcf_chain_put_by_act(goto_ch);
release_idr:
tcf_idr_release(*a, bind);
return err;
}
/**
* tcf_csum_skb_nextlayer - Get next layer pointer
* @skb: sk_buff to use
* @ihl: previous summed headers length
* @ipl: complete packet length
* @jhl: next header length
*
* Check the expected next layer availability in the specified sk_buff.
* Return the next layer pointer if pass, NULL otherwise.
*/
static void *tcf_csum_skb_nextlayer(struct sk_buff *skb,
unsigned int ihl, unsigned int ipl,
unsigned int jhl)
{
int ntkoff = skb_network_offset(skb);
int hl = ihl + jhl;
if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) ||
skb_try_make_writable(skb, hl + ntkoff))
return NULL;
else
return (void *)(skb_network_header(skb) + ihl);
}
static int tcf_csum_ipv4_icmp(struct sk_buff *skb, unsigned int ihl,
unsigned int ipl)
{
struct icmphdr *icmph;
icmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmph));
if (icmph == NULL)
return 0;
icmph->checksum = 0;
skb->csum = csum_partial(icmph, ipl - ihl, 0);
icmph->checksum = csum_fold(skb->csum);
skb->ip_summed = CHECKSUM_NONE;
return 1;
}
static int tcf_csum_ipv4_igmp(struct sk_buff *skb,
unsigned int ihl, unsigned int ipl)
{
struct igmphdr *igmph;
igmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*igmph));
if (igmph == NULL)
return 0;
igmph->csum = 0;
skb->csum = csum_partial(igmph, ipl - ihl, 0);
igmph->csum = csum_fold(skb->csum);
skb->ip_summed = CHECKSUM_NONE;
return 1;
}
static int tcf_csum_ipv6_icmp(struct sk_buff *skb, unsigned int ihl,
unsigned int ipl)
{
struct icmp6hdr *icmp6h;
const struct ipv6hdr *ip6h;
icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h));
if (icmp6h == NULL)
return 0;
ip6h = ipv6_hdr(skb);
icmp6h->icmp6_cksum = 0;
skb->csum = csum_partial(icmp6h, ipl - ihl, 0);
icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
ipl - ihl, IPPROTO_ICMPV6,
skb->csum);
skb->ip_summed = CHECKSUM_NONE;
return 1;
}
static int tcf_csum_ipv4_tcp(struct sk_buff *skb, unsigned int ihl,
unsigned int ipl)
{
struct tcphdr *tcph;
const struct iphdr *iph;
if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
return 1;
tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
if (tcph == NULL)
return 0;
iph = ip_hdr(skb);
tcph->check = 0;
skb->csum = csum_partial(tcph, ipl - ihl, 0);
tcph->check = tcp_v4_check(ipl - ihl,
iph->saddr, iph->daddr, skb->csum);
skb->ip_summed = CHECKSUM_NONE;
return 1;
}
static int tcf_csum_ipv6_tcp(struct sk_buff *skb, unsigned int ihl,
unsigned int ipl)
{
struct tcphdr *tcph;
const struct ipv6hdr *ip6h;
if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
return 1;
tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
if (tcph == NULL)
return 0;
ip6h = ipv6_hdr(skb);
tcph->check = 0;
skb->csum = csum_partial(tcph, ipl - ihl, 0);
tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
ipl - ihl, IPPROTO_TCP,
skb->csum);
skb->ip_summed = CHECKSUM_NONE;
return 1;
}
static int tcf_csum_ipv4_udp(struct sk_buff *skb, unsigned int ihl,
unsigned int ipl, int udplite)
{
struct udphdr *udph;
const struct iphdr *iph;
u16 ul;
if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
return 1;
/*
* Support both UDP and UDPLITE checksum algorithms, Don't use
* udph->len to get the real length without any protocol check,
* UDPLITE uses udph->len for another thing,
* Use iph->tot_len, or just ipl.
*/
udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
if (udph == NULL)
return 0;
iph = ip_hdr(skb);
ul = ntohs(udph->len);
if (udplite || udph->check) {
udph->check = 0;
if (udplite) {
if (ul == 0)
skb->csum = csum_partial(udph, ipl - ihl, 0);
else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
skb->csum = csum_partial(udph, ul, 0);
else
goto ignore_obscure_skb;
} else {
if (ul != ipl - ihl)
goto ignore_obscure_skb;
skb->csum = csum_partial(udph, ul, 0);
}
udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
ul, iph->protocol,
skb->csum);
if (!udph->check)
udph->check = CSUM_MANGLED_0;
}
skb->ip_summed = CHECKSUM_NONE;
ignore_obscure_skb:
return 1;
}
static int tcf_csum_ipv6_udp(struct sk_buff *skb, unsigned int ihl,
unsigned int ipl, int udplite)
{
struct udphdr *udph;
const struct ipv6hdr *ip6h;
u16 ul;
if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
return 1;
/*
* Support both UDP and UDPLITE checksum algorithms, Don't use
* udph->len to get the real length without any protocol check,
* UDPLITE uses udph->len for another thing,
* Use ip6h->payload_len + sizeof(*ip6h) ... , or just ipl.
*/
udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
if (udph == NULL)
return 0;
ip6h = ipv6_hdr(skb);
ul = ntohs(udph->len);
udph->check = 0;
if (udplite) {
if (ul == 0)
skb->csum = csum_partial(udph, ipl - ihl, 0);
else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
skb->csum = csum_partial(udph, ul, 0);
else
goto ignore_obscure_skb;
} else {
if (ul != ipl - ihl)
goto ignore_obscure_skb;
skb->csum = csum_partial(udph, ul, 0);
}
udph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ul,
udplite ? IPPROTO_UDPLITE : IPPROTO_UDP,
skb->csum);
if (!udph->check)
udph->check = CSUM_MANGLED_0;
skb->ip_summed = CHECKSUM_NONE;
ignore_obscure_skb:
return 1;
}
static int tcf_csum_sctp(struct sk_buff *skb, unsigned int ihl,
unsigned int ipl)
{
struct sctphdr *sctph;
if (skb_is_gso(skb) && skb_is_gso_sctp(skb))
return 1;
sctph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*sctph));
if (!sctph)
return 0;
sctph->checksum = sctp_compute_cksum(skb,
skb_network_offset(skb) + ihl);
skb->ip_summed = CHECKSUM_NONE;
skb->csum_not_inet = 0;
return 1;
}
static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
{
const struct iphdr *iph;
int ntkoff;
ntkoff = skb_network_offset(skb);
if (!pskb_may_pull(skb, sizeof(*iph) + ntkoff))
goto fail;
iph = ip_hdr(skb);
switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
case IPPROTO_ICMP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
if (!tcf_csum_ipv4_icmp(skb, iph->ihl * 4,
ntohs(iph->tot_len)))
goto fail;
break;
case IPPROTO_IGMP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_IGMP)
if (!tcf_csum_ipv4_igmp(skb, iph->ihl * 4,
ntohs(iph->tot_len)))
goto fail;
break;
case IPPROTO_TCP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
if (!tcf_csum_ipv4_tcp(skb, iph->ihl * 4,
ntohs(iph->tot_len)))
goto fail;
break;
case IPPROTO_UDP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
ntohs(iph->tot_len), 0))
goto fail;
break;
case IPPROTO_UDPLITE:
if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
ntohs(iph->tot_len), 1))
goto fail;
break;
case IPPROTO_SCTP:
if ((update_flags & TCA_CSUM_UPDATE_FLAG_SCTP) &&
!tcf_csum_sctp(skb, iph->ihl * 4, ntohs(iph->tot_len)))
goto fail;
break;
}
if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) {
if (skb_try_make_writable(skb, sizeof(*iph) + ntkoff))
goto fail;
ip_send_check(ip_hdr(skb));
}
return 1;
fail:
return 0;
}
static int tcf_csum_ipv6_hopopts(struct ipv6_opt_hdr *ip6xh, unsigned int ixhl,
unsigned int *pl)
{
int off, len, optlen;
unsigned char *xh = (void *)ip6xh;
off = sizeof(*ip6xh);
len = ixhl - off;
while (len > 1) {
switch (xh[off]) {
case IPV6_TLV_PAD1:
optlen = 1;
break;
case IPV6_TLV_JUMBO:
optlen = xh[off + 1] + 2;
if (optlen != 6 || len < 6 || (off & 3) != 2)
/* wrong jumbo option length/alignment */
return 0;
*pl = ntohl(*(__be32 *)(xh + off + 2));
goto done;
default:
optlen = xh[off + 1] + 2;
if (optlen > len)
/* ignore obscure options */
goto done;
break;
}
off += optlen;
len -= optlen;
}
done:
return 1;
}
static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags)
{
struct ipv6hdr *ip6h;
struct ipv6_opt_hdr *ip6xh;
unsigned int hl, ixhl;
unsigned int pl;
int ntkoff;
u8 nexthdr;
ntkoff = skb_network_offset(skb);
hl = sizeof(*ip6h);
if (!pskb_may_pull(skb, hl + ntkoff))
goto fail;
ip6h = ipv6_hdr(skb);
pl = ntohs(ip6h->payload_len);
nexthdr = ip6h->nexthdr;
do {
switch (nexthdr) {
case NEXTHDR_FRAGMENT:
goto ignore_skb;
case NEXTHDR_ROUTING:
case NEXTHDR_HOP:
case NEXTHDR_DEST:
if (!pskb_may_pull(skb, hl + sizeof(*ip6xh) + ntkoff))
goto fail;
ip6xh = (void *)(skb_network_header(skb) + hl);
ixhl = ipv6_optlen(ip6xh);
if (!pskb_may_pull(skb, hl + ixhl + ntkoff))
goto fail;
ip6xh = (void *)(skb_network_header(skb) + hl);
if ((nexthdr == NEXTHDR_HOP) &&
!(tcf_csum_ipv6_hopopts(ip6xh, ixhl, &pl)))
goto fail;
nexthdr = ip6xh->nexthdr;
hl += ixhl;
break;
case IPPROTO_ICMPV6:
if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
if (!tcf_csum_ipv6_icmp(skb,
hl, pl + sizeof(*ip6h)))
goto fail;
goto done;
case IPPROTO_TCP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
if (!tcf_csum_ipv6_tcp(skb,
hl, pl + sizeof(*ip6h)))
goto fail;
goto done;
case IPPROTO_UDP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
if (!tcf_csum_ipv6_udp(skb, hl,
pl + sizeof(*ip6h), 0))
goto fail;
goto done;
case IPPROTO_UDPLITE:
if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
if (!tcf_csum_ipv6_udp(skb, hl,
pl + sizeof(*ip6h), 1))
goto fail;
goto done;
case IPPROTO_SCTP:
if ((update_flags & TCA_CSUM_UPDATE_FLAG_SCTP) &&
!tcf_csum_sctp(skb, hl, pl + sizeof(*ip6h)))
goto fail;
goto done;
default:
goto ignore_skb;
}
} while (pskb_may_pull(skb, hl + 1 + ntkoff));
done:
ignore_skb:
return 1;
fail:
return 0;
}
static int tcf_csum_act(struct sk_buff *skb, const struct tc_action *a,
struct tcf_result *res)
{
struct tcf_csum *p = to_tcf_csum(a);
bool orig_vlan_tag_present = false;
unsigned int vlan_hdr_count = 0;
struct tcf_csum_params *params;
u32 update_flags;
__be16 protocol;
int action;
params = rcu_dereference_bh(p->params);
tcf_lastuse_update(&p->tcf_tm);
bstats_cpu_update(this_cpu_ptr(p->common.cpu_bstats), skb);
action = READ_ONCE(p->tcf_action);
if (unlikely(action == TC_ACT_SHOT))
goto drop;
update_flags = params->update_flags;
protocol = tc_skb_protocol(skb);
again:
switch (protocol) {
case cpu_to_be16(ETH_P_IP):
if (!tcf_csum_ipv4(skb, update_flags))
goto drop;
break;
case cpu_to_be16(ETH_P_IPV6):
if (!tcf_csum_ipv6(skb, update_flags))
goto drop;
break;
case cpu_to_be16(ETH_P_8021AD): /* fall through */
case cpu_to_be16(ETH_P_8021Q):
if (skb_vlan_tag_present(skb) && !orig_vlan_tag_present) {
protocol = skb->protocol;
orig_vlan_tag_present = true;
} else {
struct vlan_hdr *vlan = (struct vlan_hdr *)skb->data;
protocol = vlan->h_vlan_encapsulated_proto;
skb_pull(skb, VLAN_HLEN);
skb_reset_network_header(skb);
vlan_hdr_count++;
}
goto again;
}
out:
/* Restore the skb for the pulled VLAN tags */
while (vlan_hdr_count--) {
skb_push(skb, VLAN_HLEN);
skb_reset_network_header(skb);
}
return action;
drop:
qstats_drop_inc(this_cpu_ptr(p->common.cpu_qstats));
action = TC_ACT_SHOT;
goto out;
}
static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
int ref)
{
unsigned char *b = skb_tail_pointer(skb);
struct tcf_csum *p = to_tcf_csum(a);
struct tcf_csum_params *params;
struct tc_csum opt = {
.index = p->tcf_index,
.refcnt = refcount_read(&p->tcf_refcnt) - ref,
.bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
};
struct tcf_t t;
spin_lock_bh(&p->tcf_lock);
params = rcu_dereference_protected(p->params,
lockdep_is_held(&p->tcf_lock));
opt.action = p->tcf_action;
opt.update_flags = params->update_flags;
if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt))
goto nla_put_failure;
tcf_tm_dump(&t, &p->tcf_tm);
if (nla_put_64bit(skb, TCA_CSUM_TM, sizeof(t), &t, TCA_CSUM_PAD))
goto nla_put_failure;
spin_unlock_bh(&p->tcf_lock);
return skb->len;
nla_put_failure:
spin_unlock_bh(&p->tcf_lock);
nlmsg_trim(skb, b);
return -1;
}
static void tcf_csum_cleanup(struct tc_action *a)
{
struct tcf_csum *p = to_tcf_csum(a);
struct tcf_csum_params *params;
params = rcu_dereference_protected(p->params, 1);
if (params)
kfree_rcu(params, rcu);
}
static int tcf_csum_walker(struct net *net, struct sk_buff *skb,
struct netlink_callback *cb, int type,
const struct tc_action_ops *ops,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, csum_net_id);
return tcf_generic_walker(tn, skb, cb, type, ops, extack);
}
static int tcf_csum_search(struct net *net, struct tc_action **a, u32 index)
{
struct tc_action_net *tn = net_generic(net, csum_net_id);
return tcf_idr_search(tn, a, index);
}
static size_t tcf_csum_get_fill_size(const struct tc_action *act)
{
return nla_total_size(sizeof(struct tc_csum));
}
static struct tc_action_ops act_csum_ops = {
.kind = "csum",
.id = TCA_ID_CSUM,
.owner = THIS_MODULE,
.act = tcf_csum_act,
.dump = tcf_csum_dump,
.init = tcf_csum_init,
.cleanup = tcf_csum_cleanup,
.walk = tcf_csum_walker,
.lookup = tcf_csum_search,
.get_fill_size = tcf_csum_get_fill_size,
.size = sizeof(struct tcf_csum),
};
static __net_init int csum_init_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, csum_net_id);
return tc_action_net_init(tn, &act_csum_ops);
}
static void __net_exit csum_exit_net(struct list_head *net_list)
{
tc_action_net_exit(net_list, csum_net_id);
}
static struct pernet_operations csum_net_ops = {
.init = csum_init_net,
.exit_batch = csum_exit_net,
.id = &csum_net_id,
.size = sizeof(struct tc_action_net),
};
MODULE_DESCRIPTION("Checksum updating actions");
MODULE_LICENSE("GPL");
static int __init csum_init_module(void)
{
return tcf_register_action(&act_csum_ops, &csum_net_ops);
}
static void __exit csum_cleanup_module(void)
{
tcf_unregister_action(&act_csum_ops, &csum_net_ops);
}
module_init(csum_init_module);
module_exit(csum_cleanup_module);
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