linux/net/sched/act_bpf.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us>
   4 */
   5
   6#include <linux/module.h>
   7#include <linux/init.h>
   8#include <linux/kernel.h>
   9#include <linux/skbuff.h>
  10#include <linux/rtnetlink.h>
  11#include <linux/filter.h>
  12#include <linux/bpf.h>
  13
  14#include <net/netlink.h>
  15#include <net/sock.h>
  16#include <net/pkt_sched.h>
  17#include <net/pkt_cls.h>
  18
  19#include <linux/tc_act/tc_bpf.h>
  20#include <net/tc_act/tc_bpf.h>
  21
  22#define ACT_BPF_NAME_LEN        256
  23
  24struct tcf_bpf_cfg {
  25        struct bpf_prog *filter;
  26        struct sock_filter *bpf_ops;
  27        const char *bpf_name;
  28        u16 bpf_num_ops;
  29        bool is_ebpf;
  30};
  31
  32static unsigned int bpf_net_id;
  33static struct tc_action_ops act_bpf_ops;
  34
  35static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act,
  36                       struct tcf_result *res)
  37{
  38        bool at_ingress = skb_at_tc_ingress(skb);
  39        struct tcf_bpf *prog = to_bpf(act);
  40        struct bpf_prog *filter;
  41        int action, filter_res;
  42
  43        tcf_lastuse_update(&prog->tcf_tm);
  44        bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
  45
  46        filter = rcu_dereference(prog->filter);
  47        if (at_ingress) {
  48                __skb_push(skb, skb->mac_len);
  49                bpf_compute_data_pointers(skb);
  50                filter_res = BPF_PROG_RUN(filter, skb);
  51                __skb_pull(skb, skb->mac_len);
  52        } else {
  53                bpf_compute_data_pointers(skb);
  54                filter_res = BPF_PROG_RUN(filter, skb);
  55        }
  56        if (skb_sk_is_prefetched(skb) && filter_res != TC_ACT_OK)
  57                skb_orphan(skb);
  58
  59        /* A BPF program may overwrite the default action opcode.
  60         * Similarly as in cls_bpf, if filter_res == -1 we use the
  61         * default action specified from tc.
  62         *
  63         * In case a different well-known TC_ACT opcode has been
  64         * returned, it will overwrite the default one.
  65         *
  66         * For everything else that is unknown, TC_ACT_UNSPEC is
  67         * returned.
  68         */
  69        switch (filter_res) {
  70        case TC_ACT_PIPE:
  71        case TC_ACT_RECLASSIFY:
  72        case TC_ACT_OK:
  73        case TC_ACT_REDIRECT:
  74                action = filter_res;
  75                break;
  76        case TC_ACT_SHOT:
  77                action = filter_res;
  78                qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
  79                break;
  80        case TC_ACT_UNSPEC:
  81                action = prog->tcf_action;
  82                break;
  83        default:
  84                action = TC_ACT_UNSPEC;
  85                break;
  86        }
  87
  88        return action;
  89}
  90
  91static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
  92{
  93        return !prog->bpf_ops;
  94}
  95
  96static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
  97                                 struct sk_buff *skb)
  98{
  99        struct nlattr *nla;
 100
 101        if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
 102                return -EMSGSIZE;
 103
 104        nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
 105                          sizeof(struct sock_filter));
 106        if (nla == NULL)
 107                return -EMSGSIZE;
 108
 109        memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
 110
 111        return 0;
 112}
 113
 114static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
 115                                  struct sk_buff *skb)
 116{
 117        struct nlattr *nla;
 118
 119        if (prog->bpf_name &&
 120            nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 121                return -EMSGSIZE;
 122
 123        if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
 124                return -EMSGSIZE;
 125
 126        nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
 127        if (nla == NULL)
 128                return -EMSGSIZE;
 129
 130        memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
 131
 132        return 0;
 133}
 134
 135static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 136                        int bind, int ref)
 137{
 138        unsigned char *tp = skb_tail_pointer(skb);
 139        struct tcf_bpf *prog = to_bpf(act);
 140        struct tc_act_bpf opt = {
 141                .index   = prog->tcf_index,
 142                .refcnt  = refcount_read(&prog->tcf_refcnt) - ref,
 143                .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
 144        };
 145        struct tcf_t tm;
 146        int ret;
 147
 148        spin_lock_bh(&prog->tcf_lock);
 149        opt.action = prog->tcf_action;
 150        if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 151                goto nla_put_failure;
 152
 153        if (tcf_bpf_is_ebpf(prog))
 154                ret = tcf_bpf_dump_ebpf_info(prog, skb);
 155        else
 156                ret = tcf_bpf_dump_bpf_info(prog, skb);
 157        if (ret)
 158                goto nla_put_failure;
 159
 160        tcf_tm_dump(&tm, &prog->tcf_tm);
 161        if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
 162                          TCA_ACT_BPF_PAD))
 163                goto nla_put_failure;
 164
 165        spin_unlock_bh(&prog->tcf_lock);
 166        return skb->len;
 167
 168nla_put_failure:
 169        spin_unlock_bh(&prog->tcf_lock);
 170        nlmsg_trim(skb, tp);
 171        return -1;
 172}
 173
 174static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
 175        [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
 176        [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
 177        [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING,
 178                                    .len = ACT_BPF_NAME_LEN },
 179        [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
 180        [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
 181                                    .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
 182};
 183
 184static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 185{
 186        struct sock_filter *bpf_ops;
 187        struct sock_fprog_kern fprog_tmp;
 188        struct bpf_prog *fp;
 189        u16 bpf_size, bpf_num_ops;
 190        int ret;
 191
 192        bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
 193        if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
 194                return -EINVAL;
 195
 196        bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 197        if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
 198                return -EINVAL;
 199
 200        bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
 201        if (bpf_ops == NULL)
 202                return -ENOMEM;
 203
 204        fprog_tmp.len = bpf_num_ops;
 205        fprog_tmp.filter = bpf_ops;
 206
 207        ret = bpf_prog_create(&fp, &fprog_tmp);
 208        if (ret < 0) {
 209                kfree(bpf_ops);
 210                return ret;
 211        }
 212
 213        cfg->bpf_ops = bpf_ops;
 214        cfg->bpf_num_ops = bpf_num_ops;
 215        cfg->filter = fp;
 216        cfg->is_ebpf = false;
 217
 218        return 0;
 219}
 220
 221static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 222{
 223        struct bpf_prog *fp;
 224        char *name = NULL;
 225        u32 bpf_fd;
 226
 227        bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 228
 229        fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
 230        if (IS_ERR(fp))
 231                return PTR_ERR(fp);
 232
 233        if (tb[TCA_ACT_BPF_NAME]) {
 234                name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
 235                if (!name) {
 236                        bpf_prog_put(fp);
 237                        return -ENOMEM;
 238                }
 239        }
 240
 241        cfg->bpf_name = name;
 242        cfg->filter = fp;
 243        cfg->is_ebpf = true;
 244
 245        return 0;
 246}
 247
 248static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
 249{
 250        struct bpf_prog *filter = cfg->filter;
 251
 252        if (filter) {
 253                if (cfg->is_ebpf)
 254                        bpf_prog_put(filter);
 255                else
 256                        bpf_prog_destroy(filter);
 257        }
 258
 259        kfree(cfg->bpf_ops);
 260        kfree(cfg->bpf_name);
 261}
 262
 263static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 264                                  struct tcf_bpf_cfg *cfg)
 265{
 266        cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 267        /* updates to prog->filter are prevented, since it's called either
 268         * with tcf lock or during final cleanup in rcu callback
 269         */
 270        cfg->filter = rcu_dereference_protected(prog->filter, 1);
 271
 272        cfg->bpf_ops = prog->bpf_ops;
 273        cfg->bpf_name = prog->bpf_name;
 274}
 275
 276static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 277                        struct nlattr *est, struct tc_action **act,
 278                        int replace, int bind, bool rtnl_held,
 279                        struct tcf_proto *tp, u32 flags,
 280                        struct netlink_ext_ack *extack)
 281{
 282        struct tc_action_net *tn = net_generic(net, bpf_net_id);
 283        struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 284        struct tcf_chain *goto_ch = NULL;
 285        struct tcf_bpf_cfg cfg, old;
 286        struct tc_act_bpf *parm;
 287        struct tcf_bpf *prog;
 288        bool is_bpf, is_ebpf;
 289        int ret, res = 0;
 290        u32 index;
 291
 292        if (!nla)
 293                return -EINVAL;
 294
 295        ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla,
 296                                          act_bpf_policy, NULL);
 297        if (ret < 0)
 298                return ret;
 299
 300        if (!tb[TCA_ACT_BPF_PARMS])
 301                return -EINVAL;
 302
 303        parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 304        index = parm->index;
 305        ret = tcf_idr_check_alloc(tn, &index, act, bind);
 306        if (!ret) {
 307                ret = tcf_idr_create(tn, index, est, act,
 308                                     &act_bpf_ops, bind, true, 0);
 309                if (ret < 0) {
 310                        tcf_idr_cleanup(tn, index);
 311                        return ret;
 312                }
 313
 314                res = ACT_P_CREATED;
 315        } else if (ret > 0) {
 316                /* Don't override defaults. */
 317                if (bind)
 318                        return 0;
 319
 320                if (!replace) {
 321                        tcf_idr_release(*act, bind);
 322                        return -EEXIST;
 323                }
 324        } else {
 325                return ret;
 326        }
 327
 328        ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 329        if (ret < 0)
 330                goto release_idr;
 331
 332        is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 333        is_ebpf = tb[TCA_ACT_BPF_FD];
 334
 335        if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
 336                ret = -EINVAL;
 337                goto put_chain;
 338        }
 339
 340        memset(&cfg, 0, sizeof(cfg));
 341
 342        ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 343                       tcf_bpf_init_from_efd(tb, &cfg);
 344        if (ret < 0)
 345                goto put_chain;
 346
 347        prog = to_bpf(*act);
 348
 349        spin_lock_bh(&prog->tcf_lock);
 350        if (res != ACT_P_CREATED)
 351                tcf_bpf_prog_fill_cfg(prog, &old);
 352
 353        prog->bpf_ops = cfg.bpf_ops;
 354        prog->bpf_name = cfg.bpf_name;
 355
 356        if (cfg.bpf_num_ops)
 357                prog->bpf_num_ops = cfg.bpf_num_ops;
 358
 359        goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch);
 360        rcu_assign_pointer(prog->filter, cfg.filter);
 361        spin_unlock_bh(&prog->tcf_lock);
 362
 363        if (goto_ch)
 364                tcf_chain_put_by_act(goto_ch);
 365
 366        if (res != ACT_P_CREATED) {
 367                /* make sure the program being replaced is no longer executing */
 368                synchronize_rcu();
 369                tcf_bpf_cfg_cleanup(&old);
 370        }
 371
 372        return res;
 373
 374put_chain:
 375        if (goto_ch)
 376                tcf_chain_put_by_act(goto_ch);
 377
 378release_idr:
 379        tcf_idr_release(*act, bind);
 380        return ret;
 381}
 382
 383static void tcf_bpf_cleanup(struct tc_action *act)
 384{
 385        struct tcf_bpf_cfg tmp;
 386
 387        tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
 388        tcf_bpf_cfg_cleanup(&tmp);
 389}
 390
 391static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
 392                          struct netlink_callback *cb, int type,
 393                          const struct tc_action_ops *ops,
 394                          struct netlink_ext_ack *extack)
 395{
 396        struct tc_action_net *tn = net_generic(net, bpf_net_id);
 397
 398        return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 399}
 400
 401static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
 402{
 403        struct tc_action_net *tn = net_generic(net, bpf_net_id);
 404
 405        return tcf_idr_search(tn, a, index);
 406}
 407
 408static struct tc_action_ops act_bpf_ops __read_mostly = {
 409        .kind           =       "bpf",
 410        .id             =       TCA_ID_BPF,
 411        .owner          =       THIS_MODULE,
 412        .act            =       tcf_bpf_act,
 413        .dump           =       tcf_bpf_dump,
 414        .cleanup        =       tcf_bpf_cleanup,
 415        .init           =       tcf_bpf_init,
 416        .walk           =       tcf_bpf_walker,
 417        .lookup         =       tcf_bpf_search,
 418        .size           =       sizeof(struct tcf_bpf),
 419};
 420
 421static __net_init int bpf_init_net(struct net *net)
 422{
 423        struct tc_action_net *tn = net_generic(net, bpf_net_id);
 424
 425        return tc_action_net_init(net, tn, &act_bpf_ops);
 426}
 427
 428static void __net_exit bpf_exit_net(struct list_head *net_list)
 429{
 430        tc_action_net_exit(net_list, bpf_net_id);
 431}
 432
 433static struct pernet_operations bpf_net_ops = {
 434        .init = bpf_init_net,
 435        .exit_batch = bpf_exit_net,
 436        .id   = &bpf_net_id,
 437        .size = sizeof(struct tc_action_net),
 438};
 439
 440static int __init bpf_init_module(void)
 441{
 442        return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
 443}
 444
 445static void __exit bpf_cleanup_module(void)
 446{
 447        tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
 448}
 449
 450module_init(bpf_init_module);
 451module_exit(bpf_cleanup_module);
 452
 453MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 454MODULE_DESCRIPTION("TC BPF based action");
 455MODULE_LICENSE("GPL v2");
 456