![Dmytro Linkin](/assets/img/avatar_default.png)
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>
456 lines
10 KiB
C
456 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us>
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/rtnetlink.h>
|
|
#include <linux/filter.h>
|
|
#include <linux/bpf.h>
|
|
|
|
#include <net/netlink.h>
|
|
#include <net/pkt_sched.h>
|
|
#include <net/pkt_cls.h>
|
|
|
|
#include <linux/tc_act/tc_bpf.h>
|
|
#include <net/tc_act/tc_bpf.h>
|
|
|
|
#define ACT_BPF_NAME_LEN 256
|
|
|
|
struct tcf_bpf_cfg {
|
|
struct bpf_prog *filter;
|
|
struct sock_filter *bpf_ops;
|
|
const char *bpf_name;
|
|
u16 bpf_num_ops;
|
|
bool is_ebpf;
|
|
};
|
|
|
|
static unsigned int bpf_net_id;
|
|
static struct tc_action_ops act_bpf_ops;
|
|
|
|
static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act,
|
|
struct tcf_result *res)
|
|
{
|
|
bool at_ingress = skb_at_tc_ingress(skb);
|
|
struct tcf_bpf *prog = to_bpf(act);
|
|
struct bpf_prog *filter;
|
|
int action, filter_res;
|
|
|
|
tcf_lastuse_update(&prog->tcf_tm);
|
|
bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
|
|
|
|
rcu_read_lock();
|
|
filter = rcu_dereference(prog->filter);
|
|
if (at_ingress) {
|
|
__skb_push(skb, skb->mac_len);
|
|
bpf_compute_data_pointers(skb);
|
|
filter_res = BPF_PROG_RUN(filter, skb);
|
|
__skb_pull(skb, skb->mac_len);
|
|
} else {
|
|
bpf_compute_data_pointers(skb);
|
|
filter_res = BPF_PROG_RUN(filter, skb);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/* A BPF program may overwrite the default action opcode.
|
|
* Similarly as in cls_bpf, if filter_res == -1 we use the
|
|
* default action specified from tc.
|
|
*
|
|
* In case a different well-known TC_ACT opcode has been
|
|
* returned, it will overwrite the default one.
|
|
*
|
|
* For everything else that is unkown, TC_ACT_UNSPEC is
|
|
* returned.
|
|
*/
|
|
switch (filter_res) {
|
|
case TC_ACT_PIPE:
|
|
case TC_ACT_RECLASSIFY:
|
|
case TC_ACT_OK:
|
|
case TC_ACT_REDIRECT:
|
|
action = filter_res;
|
|
break;
|
|
case TC_ACT_SHOT:
|
|
action = filter_res;
|
|
qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
|
|
break;
|
|
case TC_ACT_UNSPEC:
|
|
action = prog->tcf_action;
|
|
break;
|
|
default:
|
|
action = TC_ACT_UNSPEC;
|
|
break;
|
|
}
|
|
|
|
return action;
|
|
}
|
|
|
|
static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
|
|
{
|
|
return !prog->bpf_ops;
|
|
}
|
|
|
|
static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
|
|
struct sk_buff *skb)
|
|
{
|
|
struct nlattr *nla;
|
|
|
|
if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
|
|
return -EMSGSIZE;
|
|
|
|
nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
|
|
sizeof(struct sock_filter));
|
|
if (nla == NULL)
|
|
return -EMSGSIZE;
|
|
|
|
memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
|
|
struct sk_buff *skb)
|
|
{
|
|
struct nlattr *nla;
|
|
|
|
if (prog->bpf_name &&
|
|
nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
|
|
return -EMSGSIZE;
|
|
|
|
if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
|
|
return -EMSGSIZE;
|
|
|
|
nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
|
|
if (nla == NULL)
|
|
return -EMSGSIZE;
|
|
|
|
memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
|
|
int bind, int ref)
|
|
{
|
|
unsigned char *tp = skb_tail_pointer(skb);
|
|
struct tcf_bpf *prog = to_bpf(act);
|
|
struct tc_act_bpf opt = {
|
|
.index = prog->tcf_index,
|
|
.refcnt = refcount_read(&prog->tcf_refcnt) - ref,
|
|
.bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
|
|
};
|
|
struct tcf_t tm;
|
|
int ret;
|
|
|
|
spin_lock_bh(&prog->tcf_lock);
|
|
opt.action = prog->tcf_action;
|
|
if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
|
|
goto nla_put_failure;
|
|
|
|
if (tcf_bpf_is_ebpf(prog))
|
|
ret = tcf_bpf_dump_ebpf_info(prog, skb);
|
|
else
|
|
ret = tcf_bpf_dump_bpf_info(prog, skb);
|
|
if (ret)
|
|
goto nla_put_failure;
|
|
|
|
tcf_tm_dump(&tm, &prog->tcf_tm);
|
|
if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
|
|
TCA_ACT_BPF_PAD))
|
|
goto nla_put_failure;
|
|
|
|
spin_unlock_bh(&prog->tcf_lock);
|
|
return skb->len;
|
|
|
|
nla_put_failure:
|
|
spin_unlock_bh(&prog->tcf_lock);
|
|
nlmsg_trim(skb, tp);
|
|
return -1;
|
|
}
|
|
|
|
static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
|
|
[TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) },
|
|
[TCA_ACT_BPF_FD] = { .type = NLA_U32 },
|
|
[TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING,
|
|
.len = ACT_BPF_NAME_LEN },
|
|
[TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 },
|
|
[TCA_ACT_BPF_OPS] = { .type = NLA_BINARY,
|
|
.len = sizeof(struct sock_filter) * BPF_MAXINSNS },
|
|
};
|
|
|
|
static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
|
|
{
|
|
struct sock_filter *bpf_ops;
|
|
struct sock_fprog_kern fprog_tmp;
|
|
struct bpf_prog *fp;
|
|
u16 bpf_size, bpf_num_ops;
|
|
int ret;
|
|
|
|
bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
|
|
if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
|
|
return -EINVAL;
|
|
|
|
bpf_size = bpf_num_ops * sizeof(*bpf_ops);
|
|
if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
|
|
return -EINVAL;
|
|
|
|
bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
|
|
if (bpf_ops == NULL)
|
|
return -ENOMEM;
|
|
|
|
fprog_tmp.len = bpf_num_ops;
|
|
fprog_tmp.filter = bpf_ops;
|
|
|
|
ret = bpf_prog_create(&fp, &fprog_tmp);
|
|
if (ret < 0) {
|
|
kfree(bpf_ops);
|
|
return ret;
|
|
}
|
|
|
|
cfg->bpf_ops = bpf_ops;
|
|
cfg->bpf_num_ops = bpf_num_ops;
|
|
cfg->filter = fp;
|
|
cfg->is_ebpf = false;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
|
|
{
|
|
struct bpf_prog *fp;
|
|
char *name = NULL;
|
|
u32 bpf_fd;
|
|
|
|
bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
|
|
|
|
fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
|
|
if (IS_ERR(fp))
|
|
return PTR_ERR(fp);
|
|
|
|
if (tb[TCA_ACT_BPF_NAME]) {
|
|
name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
|
|
if (!name) {
|
|
bpf_prog_put(fp);
|
|
return -ENOMEM;
|
|
}
|
|
}
|
|
|
|
cfg->bpf_name = name;
|
|
cfg->filter = fp;
|
|
cfg->is_ebpf = true;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
|
|
{
|
|
struct bpf_prog *filter = cfg->filter;
|
|
|
|
if (filter) {
|
|
if (cfg->is_ebpf)
|
|
bpf_prog_put(filter);
|
|
else
|
|
bpf_prog_destroy(filter);
|
|
}
|
|
|
|
kfree(cfg->bpf_ops);
|
|
kfree(cfg->bpf_name);
|
|
}
|
|
|
|
static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
|
|
struct tcf_bpf_cfg *cfg)
|
|
{
|
|
cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
|
|
/* updates to prog->filter are prevented, since it's called either
|
|
* with tcf lock or during final cleanup in rcu callback
|
|
*/
|
|
cfg->filter = rcu_dereference_protected(prog->filter, 1);
|
|
|
|
cfg->bpf_ops = prog->bpf_ops;
|
|
cfg->bpf_name = prog->bpf_name;
|
|
}
|
|
|
|
static int tcf_bpf_init(struct net *net, struct nlattr *nla,
|
|
struct nlattr *est, struct tc_action **act,
|
|
int replace, int bind, bool rtnl_held,
|
|
struct tcf_proto *tp, struct netlink_ext_ack *extack)
|
|
{
|
|
struct tc_action_net *tn = net_generic(net, bpf_net_id);
|
|
struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
|
|
struct tcf_chain *goto_ch = NULL;
|
|
struct tcf_bpf_cfg cfg, old;
|
|
struct tc_act_bpf *parm;
|
|
struct tcf_bpf *prog;
|
|
bool is_bpf, is_ebpf;
|
|
int ret, res = 0;
|
|
u32 index;
|
|
|
|
if (!nla)
|
|
return -EINVAL;
|
|
|
|
ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla,
|
|
act_bpf_policy, NULL);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
if (!tb[TCA_ACT_BPF_PARMS])
|
|
return -EINVAL;
|
|
|
|
parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
|
|
index = parm->index;
|
|
ret = tcf_idr_check_alloc(tn, &index, act, bind);
|
|
if (!ret) {
|
|
ret = tcf_idr_create(tn, index, est, act,
|
|
&act_bpf_ops, bind, true);
|
|
if (ret < 0) {
|
|
tcf_idr_cleanup(tn, index);
|
|
return ret;
|
|
}
|
|
|
|
res = ACT_P_CREATED;
|
|
} else if (ret > 0) {
|
|
/* Don't override defaults. */
|
|
if (bind)
|
|
return 0;
|
|
|
|
if (!replace) {
|
|
tcf_idr_release(*act, bind);
|
|
return -EEXIST;
|
|
}
|
|
} else {
|
|
return ret;
|
|
}
|
|
|
|
ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
|
|
if (ret < 0)
|
|
goto release_idr;
|
|
|
|
is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
|
|
is_ebpf = tb[TCA_ACT_BPF_FD];
|
|
|
|
if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
|
|
ret = -EINVAL;
|
|
goto put_chain;
|
|
}
|
|
|
|
memset(&cfg, 0, sizeof(cfg));
|
|
|
|
ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
|
|
tcf_bpf_init_from_efd(tb, &cfg);
|
|
if (ret < 0)
|
|
goto put_chain;
|
|
|
|
prog = to_bpf(*act);
|
|
|
|
spin_lock_bh(&prog->tcf_lock);
|
|
if (res != ACT_P_CREATED)
|
|
tcf_bpf_prog_fill_cfg(prog, &old);
|
|
|
|
prog->bpf_ops = cfg.bpf_ops;
|
|
prog->bpf_name = cfg.bpf_name;
|
|
|
|
if (cfg.bpf_num_ops)
|
|
prog->bpf_num_ops = cfg.bpf_num_ops;
|
|
|
|
goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch);
|
|
rcu_assign_pointer(prog->filter, cfg.filter);
|
|
spin_unlock_bh(&prog->tcf_lock);
|
|
|
|
if (goto_ch)
|
|
tcf_chain_put_by_act(goto_ch);
|
|
|
|
if (res == ACT_P_CREATED) {
|
|
tcf_idr_insert(tn, *act);
|
|
} else {
|
|
/* make sure the program being replaced is no longer executing */
|
|
synchronize_rcu();
|
|
tcf_bpf_cfg_cleanup(&old);
|
|
}
|
|
|
|
return res;
|
|
|
|
put_chain:
|
|
if (goto_ch)
|
|
tcf_chain_put_by_act(goto_ch);
|
|
|
|
release_idr:
|
|
tcf_idr_release(*act, bind);
|
|
return ret;
|
|
}
|
|
|
|
static void tcf_bpf_cleanup(struct tc_action *act)
|
|
{
|
|
struct tcf_bpf_cfg tmp;
|
|
|
|
tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
|
|
tcf_bpf_cfg_cleanup(&tmp);
|
|
}
|
|
|
|
static int tcf_bpf_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, bpf_net_id);
|
|
|
|
return tcf_generic_walker(tn, skb, cb, type, ops, extack);
|
|
}
|
|
|
|
static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
|
|
{
|
|
struct tc_action_net *tn = net_generic(net, bpf_net_id);
|
|
|
|
return tcf_idr_search(tn, a, index);
|
|
}
|
|
|
|
static struct tc_action_ops act_bpf_ops __read_mostly = {
|
|
.kind = "bpf",
|
|
.id = TCA_ID_BPF,
|
|
.owner = THIS_MODULE,
|
|
.act = tcf_bpf_act,
|
|
.dump = tcf_bpf_dump,
|
|
.cleanup = tcf_bpf_cleanup,
|
|
.init = tcf_bpf_init,
|
|
.walk = tcf_bpf_walker,
|
|
.lookup = tcf_bpf_search,
|
|
.size = sizeof(struct tcf_bpf),
|
|
};
|
|
|
|
static __net_init int bpf_init_net(struct net *net)
|
|
{
|
|
struct tc_action_net *tn = net_generic(net, bpf_net_id);
|
|
|
|
return tc_action_net_init(tn, &act_bpf_ops);
|
|
}
|
|
|
|
static void __net_exit bpf_exit_net(struct list_head *net_list)
|
|
{
|
|
tc_action_net_exit(net_list, bpf_net_id);
|
|
}
|
|
|
|
static struct pernet_operations bpf_net_ops = {
|
|
.init = bpf_init_net,
|
|
.exit_batch = bpf_exit_net,
|
|
.id = &bpf_net_id,
|
|
.size = sizeof(struct tc_action_net),
|
|
};
|
|
|
|
static int __init bpf_init_module(void)
|
|
{
|
|
return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
|
|
}
|
|
|
|
static void __exit bpf_cleanup_module(void)
|
|
{
|
|
tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
|
|
}
|
|
|
|
module_init(bpf_init_module);
|
|
module_exit(bpf_cleanup_module);
|
|
|
|
MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
|
|
MODULE_DESCRIPTION("TC BPF based action");
|
|
MODULE_LICENSE("GPL v2");
|