linux/net/sched/cls_bpf.c
Andrii Nakryiko fb7dd8bca0 bpf: Refactor BPF_PROG_RUN into a function
Turn BPF_PROG_RUN into a proper always inlined function. No functional and
performance changes are intended, but it makes it much easier to understand
what's going on with how BPF programs are actually get executed. It's more
obvious what types and callbacks are expected. Also extra () around input
parameters can be dropped, as well as `__` variable prefixes intended to avoid
naming collisions, which makes the code simpler to read and write.

This refactoring also highlighted one extra issue. BPF_PROG_RUN is both
a macro and an enum value (BPF_PROG_RUN == BPF_PROG_TEST_RUN). Turning
BPF_PROG_RUN into a function causes naming conflict compilation error. So
rename BPF_PROG_RUN into lower-case bpf_prog_run(), similar to
bpf_prog_run_xdp(), bpf_prog_run_pin_on_cpu(), etc. All existing callers of
BPF_PROG_RUN, the macro, are switched to bpf_prog_run() explicitly.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210815070609.987780-2-andrii@kernel.org
2021-08-17 00:45:07 +02:00

721 lines
17 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Berkeley Packet Filter based traffic classifier
*
* Might be used to classify traffic through flexible, user-defined and
* possibly JIT-ed BPF filters for traffic control as an alternative to
* ematches.
*
* (C) 2013 Daniel Borkmann <dborkman@redhat.com>
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/filter.h>
#include <linux/bpf.h>
#include <linux/idr.h>
#include <net/rtnetlink.h>
#include <net/pkt_cls.h>
#include <net/sock.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
MODULE_DESCRIPTION("TC BPF based classifier");
#define CLS_BPF_NAME_LEN 256
#define CLS_BPF_SUPPORTED_GEN_FLAGS \
(TCA_CLS_FLAGS_SKIP_HW | TCA_CLS_FLAGS_SKIP_SW)
struct cls_bpf_head {
struct list_head plist;
struct idr handle_idr;
struct rcu_head rcu;
};
struct cls_bpf_prog {
struct bpf_prog *filter;
struct list_head link;
struct tcf_result res;
bool exts_integrated;
u32 gen_flags;
unsigned int in_hw_count;
struct tcf_exts exts;
u32 handle;
u16 bpf_num_ops;
struct sock_filter *bpf_ops;
const char *bpf_name;
struct tcf_proto *tp;
struct rcu_work rwork;
};
static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = {
[TCA_BPF_CLASSID] = { .type = NLA_U32 },
[TCA_BPF_FLAGS] = { .type = NLA_U32 },
[TCA_BPF_FLAGS_GEN] = { .type = NLA_U32 },
[TCA_BPF_FD] = { .type = NLA_U32 },
[TCA_BPF_NAME] = { .type = NLA_NUL_STRING,
.len = CLS_BPF_NAME_LEN },
[TCA_BPF_OPS_LEN] = { .type = NLA_U16 },
[TCA_BPF_OPS] = { .type = NLA_BINARY,
.len = sizeof(struct sock_filter) * BPF_MAXINSNS },
};
static int cls_bpf_exec_opcode(int code)
{
switch (code) {
case TC_ACT_OK:
case TC_ACT_SHOT:
case TC_ACT_STOLEN:
case TC_ACT_TRAP:
case TC_ACT_REDIRECT:
case TC_ACT_UNSPEC:
return code;
default:
return TC_ACT_UNSPEC;
}
}
static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
struct tcf_result *res)
{
struct cls_bpf_head *head = rcu_dereference_bh(tp->root);
bool at_ingress = skb_at_tc_ingress(skb);
struct cls_bpf_prog *prog;
int ret = -1;
list_for_each_entry_rcu(prog, &head->plist, link) {
int filter_res;
qdisc_skb_cb(skb)->tc_classid = prog->res.classid;
if (tc_skip_sw(prog->gen_flags)) {
filter_res = prog->exts_integrated ? TC_ACT_UNSPEC : 0;
} else if (at_ingress) {
/* It is safe to push/pull even if skb_shared() */
__skb_push(skb, skb->mac_len);
bpf_compute_data_pointers(skb);
filter_res = bpf_prog_run(prog->filter, skb);
__skb_pull(skb, skb->mac_len);
} else {
bpf_compute_data_pointers(skb);
filter_res = bpf_prog_run(prog->filter, skb);
}
if (prog->exts_integrated) {
res->class = 0;
res->classid = TC_H_MAJ(prog->res.classid) |
qdisc_skb_cb(skb)->tc_classid;
ret = cls_bpf_exec_opcode(filter_res);
if (ret == TC_ACT_UNSPEC)
continue;
break;
}
if (filter_res == 0)
continue;
if (filter_res != -1) {
res->class = 0;
res->classid = filter_res;
} else {
*res = prog->res;
}
ret = tcf_exts_exec(skb, &prog->exts, res);
if (ret < 0)
continue;
break;
}
return ret;
}
static bool cls_bpf_is_ebpf(const struct cls_bpf_prog *prog)
{
return !prog->bpf_ops;
}
static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog,
struct cls_bpf_prog *oldprog,
struct netlink_ext_ack *extack)
{
struct tcf_block *block = tp->chain->block;
struct tc_cls_bpf_offload cls_bpf = {};
struct cls_bpf_prog *obj;
bool skip_sw;
int err;
skip_sw = prog && tc_skip_sw(prog->gen_flags);
obj = prog ?: oldprog;
tc_cls_common_offload_init(&cls_bpf.common, tp, obj->gen_flags, extack);
cls_bpf.command = TC_CLSBPF_OFFLOAD;
cls_bpf.exts = &obj->exts;
cls_bpf.prog = prog ? prog->filter : NULL;
cls_bpf.oldprog = oldprog ? oldprog->filter : NULL;
cls_bpf.name = obj->bpf_name;
cls_bpf.exts_integrated = obj->exts_integrated;
if (oldprog && prog)
err = tc_setup_cb_replace(block, tp, TC_SETUP_CLSBPF, &cls_bpf,
skip_sw, &oldprog->gen_flags,
&oldprog->in_hw_count,
&prog->gen_flags, &prog->in_hw_count,
true);
else if (prog)
err = tc_setup_cb_add(block, tp, TC_SETUP_CLSBPF, &cls_bpf,
skip_sw, &prog->gen_flags,
&prog->in_hw_count, true);
else
err = tc_setup_cb_destroy(block, tp, TC_SETUP_CLSBPF, &cls_bpf,
skip_sw, &oldprog->gen_flags,
&oldprog->in_hw_count, true);
if (prog && err) {
cls_bpf_offload_cmd(tp, oldprog, prog, extack);
return err;
}
if (prog && skip_sw && !(prog->gen_flags & TCA_CLS_FLAGS_IN_HW))
return -EINVAL;
return 0;
}
static u32 cls_bpf_flags(u32 flags)
{
return flags & CLS_BPF_SUPPORTED_GEN_FLAGS;
}
static int cls_bpf_offload(struct tcf_proto *tp, struct cls_bpf_prog *prog,
struct cls_bpf_prog *oldprog,
struct netlink_ext_ack *extack)
{
if (prog && oldprog &&
cls_bpf_flags(prog->gen_flags) !=
cls_bpf_flags(oldprog->gen_flags))
return -EINVAL;
if (prog && tc_skip_hw(prog->gen_flags))
prog = NULL;
if (oldprog && tc_skip_hw(oldprog->gen_flags))
oldprog = NULL;
if (!prog && !oldprog)
return 0;
return cls_bpf_offload_cmd(tp, prog, oldprog, extack);
}
static void cls_bpf_stop_offload(struct tcf_proto *tp,
struct cls_bpf_prog *prog,
struct netlink_ext_ack *extack)
{
int err;
err = cls_bpf_offload_cmd(tp, NULL, prog, extack);
if (err)
pr_err("Stopping hardware offload failed: %d\n", err);
}
static void cls_bpf_offload_update_stats(struct tcf_proto *tp,
struct cls_bpf_prog *prog)
{
struct tcf_block *block = tp->chain->block;
struct tc_cls_bpf_offload cls_bpf = {};
tc_cls_common_offload_init(&cls_bpf.common, tp, prog->gen_flags, NULL);
cls_bpf.command = TC_CLSBPF_STATS;
cls_bpf.exts = &prog->exts;
cls_bpf.prog = prog->filter;
cls_bpf.name = prog->bpf_name;
cls_bpf.exts_integrated = prog->exts_integrated;
tc_setup_cb_call(block, TC_SETUP_CLSBPF, &cls_bpf, false, true);
}
static int cls_bpf_init(struct tcf_proto *tp)
{
struct cls_bpf_head *head;
head = kzalloc(sizeof(*head), GFP_KERNEL);
if (head == NULL)
return -ENOBUFS;
INIT_LIST_HEAD_RCU(&head->plist);
idr_init(&head->handle_idr);
rcu_assign_pointer(tp->root, head);
return 0;
}
static void cls_bpf_free_parms(struct cls_bpf_prog *prog)
{
if (cls_bpf_is_ebpf(prog))
bpf_prog_put(prog->filter);
else
bpf_prog_destroy(prog->filter);
kfree(prog->bpf_name);
kfree(prog->bpf_ops);
}
static void __cls_bpf_delete_prog(struct cls_bpf_prog *prog)
{
tcf_exts_destroy(&prog->exts);
tcf_exts_put_net(&prog->exts);
cls_bpf_free_parms(prog);
kfree(prog);
}
static void cls_bpf_delete_prog_work(struct work_struct *work)
{
struct cls_bpf_prog *prog = container_of(to_rcu_work(work),
struct cls_bpf_prog,
rwork);
rtnl_lock();
__cls_bpf_delete_prog(prog);
rtnl_unlock();
}
static void __cls_bpf_delete(struct tcf_proto *tp, struct cls_bpf_prog *prog,
struct netlink_ext_ack *extack)
{
struct cls_bpf_head *head = rtnl_dereference(tp->root);
idr_remove(&head->handle_idr, prog->handle);
cls_bpf_stop_offload(tp, prog, extack);
list_del_rcu(&prog->link);
tcf_unbind_filter(tp, &prog->res);
if (tcf_exts_get_net(&prog->exts))
tcf_queue_work(&prog->rwork, cls_bpf_delete_prog_work);
else
__cls_bpf_delete_prog(prog);
}
static int cls_bpf_delete(struct tcf_proto *tp, void *arg, bool *last,
bool rtnl_held, struct netlink_ext_ack *extack)
{
struct cls_bpf_head *head = rtnl_dereference(tp->root);
__cls_bpf_delete(tp, arg, extack);
*last = list_empty(&head->plist);
return 0;
}
static void cls_bpf_destroy(struct tcf_proto *tp, bool rtnl_held,
struct netlink_ext_ack *extack)
{
struct cls_bpf_head *head = rtnl_dereference(tp->root);
struct cls_bpf_prog *prog, *tmp;
list_for_each_entry_safe(prog, tmp, &head->plist, link)
__cls_bpf_delete(tp, prog, extack);
idr_destroy(&head->handle_idr);
kfree_rcu(head, rcu);
}
static void *cls_bpf_get(struct tcf_proto *tp, u32 handle)
{
struct cls_bpf_head *head = rtnl_dereference(tp->root);
struct cls_bpf_prog *prog;
list_for_each_entry(prog, &head->plist, link) {
if (prog->handle == handle)
return prog;
}
return NULL;
}
static int cls_bpf_prog_from_ops(struct nlattr **tb, struct cls_bpf_prog *prog)
{
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_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_BPF_OPS]))
return -EINVAL;
bpf_ops = kmemdup(nla_data(tb[TCA_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;
}
prog->bpf_ops = bpf_ops;
prog->bpf_num_ops = bpf_num_ops;
prog->bpf_name = NULL;
prog->filter = fp;
return 0;
}
static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog,
u32 gen_flags, const struct tcf_proto *tp)
{
struct bpf_prog *fp;
char *name = NULL;
bool skip_sw;
u32 bpf_fd;
bpf_fd = nla_get_u32(tb[TCA_BPF_FD]);
skip_sw = gen_flags & TCA_CLS_FLAGS_SKIP_SW;
fp = bpf_prog_get_type_dev(bpf_fd, BPF_PROG_TYPE_SCHED_CLS, skip_sw);
if (IS_ERR(fp))
return PTR_ERR(fp);
if (tb[TCA_BPF_NAME]) {
name = nla_memdup(tb[TCA_BPF_NAME], GFP_KERNEL);
if (!name) {
bpf_prog_put(fp);
return -ENOMEM;
}
}
prog->bpf_ops = NULL;
prog->bpf_name = name;
prog->filter = fp;
if (fp->dst_needed)
tcf_block_netif_keep_dst(tp->chain->block);
return 0;
}
static int cls_bpf_set_parms(struct net *net, struct tcf_proto *tp,
struct cls_bpf_prog *prog, unsigned long base,
struct nlattr **tb, struct nlattr *est, u32 flags,
struct netlink_ext_ack *extack)
{
bool is_bpf, is_ebpf, have_exts = false;
u32 gen_flags = 0;
int ret;
is_bpf = tb[TCA_BPF_OPS_LEN] && tb[TCA_BPF_OPS];
is_ebpf = tb[TCA_BPF_FD];
if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf))
return -EINVAL;
ret = tcf_exts_validate(net, tp, tb, est, &prog->exts, flags,
extack);
if (ret < 0)
return ret;
if (tb[TCA_BPF_FLAGS]) {
u32 bpf_flags = nla_get_u32(tb[TCA_BPF_FLAGS]);
if (bpf_flags & ~TCA_BPF_FLAG_ACT_DIRECT)
return -EINVAL;
have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT;
}
if (tb[TCA_BPF_FLAGS_GEN]) {
gen_flags = nla_get_u32(tb[TCA_BPF_FLAGS_GEN]);
if (gen_flags & ~CLS_BPF_SUPPORTED_GEN_FLAGS ||
!tc_flags_valid(gen_flags))
return -EINVAL;
}
prog->exts_integrated = have_exts;
prog->gen_flags = gen_flags;
ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog) :
cls_bpf_prog_from_efd(tb, prog, gen_flags, tp);
if (ret < 0)
return ret;
if (tb[TCA_BPF_CLASSID]) {
prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
tcf_bind_filter(tp, &prog->res, base);
}
return 0;
}
static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
struct tcf_proto *tp, unsigned long base,
u32 handle, struct nlattr **tca,
void **arg, u32 flags,
struct netlink_ext_ack *extack)
{
struct cls_bpf_head *head = rtnl_dereference(tp->root);
struct cls_bpf_prog *oldprog = *arg;
struct nlattr *tb[TCA_BPF_MAX + 1];
struct cls_bpf_prog *prog;
int ret;
if (tca[TCA_OPTIONS] == NULL)
return -EINVAL;
ret = nla_parse_nested_deprecated(tb, TCA_BPF_MAX, tca[TCA_OPTIONS],
bpf_policy, NULL);
if (ret < 0)
return ret;
prog = kzalloc(sizeof(*prog), GFP_KERNEL);
if (!prog)
return -ENOBUFS;
ret = tcf_exts_init(&prog->exts, net, TCA_BPF_ACT, TCA_BPF_POLICE);
if (ret < 0)
goto errout;
if (oldprog) {
if (handle && oldprog->handle != handle) {
ret = -EINVAL;
goto errout;
}
}
if (handle == 0) {
handle = 1;
ret = idr_alloc_u32(&head->handle_idr, prog, &handle,
INT_MAX, GFP_KERNEL);
} else if (!oldprog) {
ret = idr_alloc_u32(&head->handle_idr, prog, &handle,
handle, GFP_KERNEL);
}
if (ret)
goto errout;
prog->handle = handle;
ret = cls_bpf_set_parms(net, tp, prog, base, tb, tca[TCA_RATE], flags,
extack);
if (ret < 0)
goto errout_idr;
ret = cls_bpf_offload(tp, prog, oldprog, extack);
if (ret)
goto errout_parms;
if (!tc_in_hw(prog->gen_flags))
prog->gen_flags |= TCA_CLS_FLAGS_NOT_IN_HW;
if (oldprog) {
idr_replace(&head->handle_idr, prog, handle);
list_replace_rcu(&oldprog->link, &prog->link);
tcf_unbind_filter(tp, &oldprog->res);
tcf_exts_get_net(&oldprog->exts);
tcf_queue_work(&oldprog->rwork, cls_bpf_delete_prog_work);
} else {
list_add_rcu(&prog->link, &head->plist);
}
*arg = prog;
return 0;
errout_parms:
cls_bpf_free_parms(prog);
errout_idr:
if (!oldprog)
idr_remove(&head->handle_idr, prog->handle);
errout:
tcf_exts_destroy(&prog->exts);
kfree(prog);
return ret;
}
static int cls_bpf_dump_bpf_info(const struct cls_bpf_prog *prog,
struct sk_buff *skb)
{
struct nlattr *nla;
if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_num_ops))
return -EMSGSIZE;
nla = nla_reserve(skb, TCA_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 cls_bpf_dump_ebpf_info(const struct cls_bpf_prog *prog,
struct sk_buff *skb)
{
struct nlattr *nla;
if (prog->bpf_name &&
nla_put_string(skb, TCA_BPF_NAME, prog->bpf_name))
return -EMSGSIZE;
if (nla_put_u32(skb, TCA_BPF_ID, prog->filter->aux->id))
return -EMSGSIZE;
nla = nla_reserve(skb, TCA_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 cls_bpf_dump(struct net *net, struct tcf_proto *tp, void *fh,
struct sk_buff *skb, struct tcmsg *tm, bool rtnl_held)
{
struct cls_bpf_prog *prog = fh;
struct nlattr *nest;
u32 bpf_flags = 0;
int ret;
if (prog == NULL)
return skb->len;
tm->tcm_handle = prog->handle;
cls_bpf_offload_update_stats(tp, prog);
nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
if (nest == NULL)
goto nla_put_failure;
if (prog->res.classid &&
nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid))
goto nla_put_failure;
if (cls_bpf_is_ebpf(prog))
ret = cls_bpf_dump_ebpf_info(prog, skb);
else
ret = cls_bpf_dump_bpf_info(prog, skb);
if (ret)
goto nla_put_failure;
if (tcf_exts_dump(skb, &prog->exts) < 0)
goto nla_put_failure;
if (prog->exts_integrated)
bpf_flags |= TCA_BPF_FLAG_ACT_DIRECT;
if (bpf_flags && nla_put_u32(skb, TCA_BPF_FLAGS, bpf_flags))
goto nla_put_failure;
if (prog->gen_flags &&
nla_put_u32(skb, TCA_BPF_FLAGS_GEN, prog->gen_flags))
goto nla_put_failure;
nla_nest_end(skb, nest);
if (tcf_exts_dump_stats(skb, &prog->exts) < 0)
goto nla_put_failure;
return skb->len;
nla_put_failure:
nla_nest_cancel(skb, nest);
return -1;
}
static void cls_bpf_bind_class(void *fh, u32 classid, unsigned long cl,
void *q, unsigned long base)
{
struct cls_bpf_prog *prog = fh;
if (prog && prog->res.classid == classid) {
if (cl)
__tcf_bind_filter(q, &prog->res, base);
else
__tcf_unbind_filter(q, &prog->res);
}
}
static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg,
bool rtnl_held)
{
struct cls_bpf_head *head = rtnl_dereference(tp->root);
struct cls_bpf_prog *prog;
list_for_each_entry(prog, &head->plist, link) {
if (arg->count < arg->skip)
goto skip;
if (arg->fn(tp, prog, arg) < 0) {
arg->stop = 1;
break;
}
skip:
arg->count++;
}
}
static int cls_bpf_reoffload(struct tcf_proto *tp, bool add, flow_setup_cb_t *cb,
void *cb_priv, struct netlink_ext_ack *extack)
{
struct cls_bpf_head *head = rtnl_dereference(tp->root);
struct tcf_block *block = tp->chain->block;
struct tc_cls_bpf_offload cls_bpf = {};
struct cls_bpf_prog *prog;
int err;
list_for_each_entry(prog, &head->plist, link) {
if (tc_skip_hw(prog->gen_flags))
continue;
tc_cls_common_offload_init(&cls_bpf.common, tp, prog->gen_flags,
extack);
cls_bpf.command = TC_CLSBPF_OFFLOAD;
cls_bpf.exts = &prog->exts;
cls_bpf.prog = add ? prog->filter : NULL;
cls_bpf.oldprog = add ? NULL : prog->filter;
cls_bpf.name = prog->bpf_name;
cls_bpf.exts_integrated = prog->exts_integrated;
err = tc_setup_cb_reoffload(block, tp, add, cb, TC_SETUP_CLSBPF,
&cls_bpf, cb_priv, &prog->gen_flags,
&prog->in_hw_count);
if (err)
return err;
}
return 0;
}
static struct tcf_proto_ops cls_bpf_ops __read_mostly = {
.kind = "bpf",
.owner = THIS_MODULE,
.classify = cls_bpf_classify,
.init = cls_bpf_init,
.destroy = cls_bpf_destroy,
.get = cls_bpf_get,
.change = cls_bpf_change,
.delete = cls_bpf_delete,
.walk = cls_bpf_walk,
.reoffload = cls_bpf_reoffload,
.dump = cls_bpf_dump,
.bind_class = cls_bpf_bind_class,
};
static int __init cls_bpf_init_mod(void)
{
return register_tcf_proto_ops(&cls_bpf_ops);
}
static void __exit cls_bpf_exit_mod(void)
{
unregister_tcf_proto_ops(&cls_bpf_ops);
}
module_init(cls_bpf_init_mod);
module_exit(cls_bpf_exit_mod);