net/sched/cls_bpf.c

   1 /*
   2  * Berkeley Packet Filter based traffic classifier
   3  *
   4  * Might be used to classify traffic through flexible, user-defined and
   5  * possibly JIT-ed BPF filters for traffic control as an alternative to
   6  * ematches.
   7  *
   8  * (C) 2013 Daniel Borkmann <dborkman@redhat.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/filter.h>
  19 #include <net/rtnetlink.h>
  20 #include <net/pkt_cls.h>
  21 #include <net/sock.h>
  22
  23 MODULE_LICENSE("GPL");
  24 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
  25 MODULE_DESCRIPTION("TC BPF based classifier");
  26
  27 struct cls_bpf_head {
  28         struct list_head plist;
  29         u32 hgen;
  30 };
  31
  32 struct cls_bpf_prog {
  33         struct sk_filter *filter;
  34         struct sock_filter *bpf_ops;
  35         struct tcf_exts exts;
  36         struct tcf_result res;
  37         struct list_head link;
  38         u32 handle;
  39         u16 bpf_len;
  40 };
  41
  42 static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = {
  43         [TCA_BPF_CLASSID]       = { .type = NLA_U32 },
  44         [TCA_BPF_OPS_LEN]       = { .type = NLA_U16 },
  45         [TCA_BPF_OPS]           = { .type = NLA_BINARY,
  46                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
  47 };
  48
  49 static const struct tcf_ext_map bpf_ext_map = {
  50         .action = TCA_BPF_ACT,
  51         .police = TCA_BPF_POLICE,
  52 };
  53
  54 static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
  55                             struct tcf_result *res)
  56 {
  57         struct cls_bpf_head *head = tp->root;
  58         struct cls_bpf_prog *prog;
  59         int ret;
  60
  61         list_for_each_entry(prog, &head->plist, link) {
  62                 int filter_res = SK_RUN_FILTER(prog->filter, skb);
  63
  64                 if (filter_res == 0)
  65                         continue;
  66
  67                 *res = prog->res;
  68                 if (filter_res != -1)
  69                         res->classid = filter_res;
  70
  71                 ret = tcf_exts_exec(skb, &prog->exts, res);
  72                 if (ret < 0)
  73                         continue;
  74
  75                 return ret;
  76         }
  77
  78         return -1;
  79 }
  80
  81 static int cls_bpf_init(struct tcf_proto *tp)
  82 {
  83         struct cls_bpf_head *head;
  84
  85         head = kzalloc(sizeof(*head), GFP_KERNEL);
  86         if (head == NULL)
  87                 return -ENOBUFS;
  88
  89         INIT_LIST_HEAD(&head->plist);
  90         tp->root = head;
  91
  92         return 0;
  93 }
  94
  95 static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog)
  96 {
  97         tcf_unbind_filter(tp, &prog->res);
  98         tcf_exts_destroy(tp, &prog->exts);
  99
 100         sk_unattached_filter_destroy(prog->filter);
 101
 102         kfree(prog->bpf_ops);
 103         kfree(prog);
 104 }
 105
 106 static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
 107 {
 108         struct cls_bpf_head *head = tp->root;
 109         struct cls_bpf_prog *prog, *todel = (struct cls_bpf_prog *) arg;
 110
 111         list_for_each_entry(prog, &head->plist, link) {
 112                 if (prog == todel) {
 113                         tcf_tree_lock(tp);
 114                         list_del(&prog->link);
 115                         tcf_tree_unlock(tp);
 116
 117                         cls_bpf_delete_prog(tp, prog);
 118                         return 0;
 119                 }
 120         }
 121
 122         return -ENOENT;
 123 }
 124
 125 static void cls_bpf_destroy(struct tcf_proto *tp)
 126 {
 127         struct cls_bpf_head *head = tp->root;
 128         struct cls_bpf_prog *prog, *tmp;
 129
 130         list_for_each_entry_safe(prog, tmp, &head->plist, link) {
 131                 list_del(&prog->link);
 132                 cls_bpf_delete_prog(tp, prog);
 133         }
 134
 135         kfree(head);
 136 }
 137
 138 static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle)
 139 {
 140         struct cls_bpf_head *head = tp->root;
 141         struct cls_bpf_prog *prog;
 142         unsigned long ret = 0UL;
 143
 144         if (head == NULL)
 145                 return 0UL;
 146
 147         list_for_each_entry(prog, &head->plist, link) {
 148                 if (prog->handle == handle) {
 149                         ret = (unsigned long) prog;
 150                         break;
 151                 }
 152         }
 153
 154         return ret;
 155 }
 156
 157 static void cls_bpf_put(struct tcf_proto *tp, unsigned long f)
 158 {
 159 }
 160
 161 static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
 162                                    struct cls_bpf_prog *prog,
 163                                    unsigned long base, struct nlattr **tb,
 164                                    struct nlattr *est)
 165 {
 166         struct sock_filter *bpf_ops, *bpf_old;
 167         struct tcf_exts exts;
 168         struct sock_fprog tmp;
 169         struct sk_filter *fp, *fp_old;
 170         u16 bpf_size, bpf_len;
 171         u32 classid;
 172         int ret;
 173
 174         if (!tb[TCA_BPF_OPS_LEN] || !tb[TCA_BPF_OPS] || !tb[TCA_BPF_CLASSID])
 175                 return -EINVAL;
 176
 177         ret = tcf_exts_validate(net, tp, tb, est, &exts, &bpf_ext_map);
 178         if (ret < 0)
 179                 return ret;
 180
 181         classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
 182         bpf_len = nla_get_u16(tb[TCA_BPF_OPS_LEN]);
 183         if (bpf_len > BPF_MAXINSNS || bpf_len == 0) {
 184                 ret = -EINVAL;
 185                 goto errout;
 186         }
 187
 188         bpf_size = bpf_len * sizeof(*bpf_ops);
 189         bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
 190         if (bpf_ops == NULL) {
 191                 ret = -ENOMEM;
 192                 goto errout;
 193         }
 194
 195         memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size);
 196
 197         tmp.len = bpf_len;
 198         tmp.filter = (struct sock_filter __user *) bpf_ops;
 199
 200         ret = sk_unattached_filter_create(&fp, &tmp);
 201         if (ret)
 202                 goto errout_free;
 203
 204         tcf_tree_lock(tp);
 205         fp_old = prog->filter;
 206         bpf_old = prog->bpf_ops;
 207
 208         prog->bpf_len = bpf_len;
 209         prog->bpf_ops = bpf_ops;
 210         prog->filter = fp;
 211         prog->res.classid = classid;
 212         tcf_tree_unlock(tp);
 213
 214         tcf_bind_filter(tp, &prog->res, base);
 215         tcf_exts_change(tp, &prog->exts, &exts);
 216
 217         if (fp_old)
 218                 sk_unattached_filter_destroy(fp_old);
 219         if (bpf_old)
 220                 kfree(bpf_old);
 221
 222         return 0;
 223
 224 errout_free:
 225         kfree(bpf_ops);
 226 errout:
 227         tcf_exts_destroy(tp, &exts);
 228         return ret;
 229 }
 230
 231 static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp,
 232                                    struct cls_bpf_head *head)
 233 {
 234         unsigned int i = 0x80000000;
 235
 236         do {
 237                 if (++head->hgen == 0x7FFFFFFF)
 238                         head->hgen = 1;
 239         } while (--i > 0 && cls_bpf_get(tp, head->hgen));
 240         if (i == 0)
 241                 pr_err("Insufficient number of handles\n");
 242
 243         return i;
 244 }
 245
 246 static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
 247                           struct tcf_proto *tp, unsigned long base,
 248                           u32 handle, struct nlattr **tca,
 249                           unsigned long *arg)
 250 {
 251         struct cls_bpf_head *head = tp->root;
 252         struct cls_bpf_prog *prog = (struct cls_bpf_prog *) *arg;
 253         struct nlattr *tb[TCA_BPF_MAX + 1];
 254         int ret;
 255
 256         if (tca[TCA_OPTIONS] == NULL)
 257                 return -EINVAL;
 258
 259         ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy);
 260         if (ret < 0)
 261                 return ret;
 262
 263         if (prog != NULL) {
 264                 if (handle && prog->handle != handle)
 265                         return -EINVAL;
 266                 return cls_bpf_modify_existing(net, tp, prog, base, tb,
 267                                                tca[TCA_RATE]);
 268         }
 269
 270         prog = kzalloc(sizeof(*prog), GFP_KERNEL);
 271         if (prog == NULL)
 272                 return -ENOBUFS;
 273
 274         if (handle == 0)
 275                 prog->handle = cls_bpf_grab_new_handle(tp, head);
 276         else
 277                 prog->handle = handle;
 278         if (prog->handle == 0) {
 279                 ret = -EINVAL;
 280                 goto errout;
 281         }
 282
 283         ret = cls_bpf_modify_existing(net, tp, prog, base, tb, tca[TCA_RATE]);
 284         if (ret < 0)
 285                 goto errout;
 286
 287         tcf_tree_lock(tp);
 288         list_add(&prog->link, &head->plist);
 289         tcf_tree_unlock(tp);
 290
 291         *arg = (unsigned long) prog;
 292
 293         return 0;
 294 errout:
 295         if (*arg == 0UL && prog)
 296                 kfree(prog);
 297
 298         return ret;
 299 }
 300
 301 static int cls_bpf_dump(struct tcf_proto *tp, unsigned long fh,
 302                         struct sk_buff *skb, struct tcmsg *tm)
 303 {
 304         struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh;
 305         struct nlattr *nest, *nla;
 306
 307         if (prog == NULL)
 308                 return skb->len;
 309
 310         tm->tcm_handle = prog->handle;
 311
 312         nest = nla_nest_start(skb, TCA_OPTIONS);
 313         if (nest == NULL)
 314                 goto nla_put_failure;
 315
 316         if (nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid))
 317                 goto nla_put_failure;
 318         if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_len))
 319                 goto nla_put_failure;
 320
 321         nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_len *
 322                           sizeof(struct sock_filter));
 323         if (nla == NULL)
 324                 goto nla_put_failure;
 325
 326         memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
 327
 328         if (tcf_exts_dump(skb, &prog->exts, &bpf_ext_map) < 0)
 329                 goto nla_put_failure;
 330
 331         nla_nest_end(skb, nest);
 332
 333         if (tcf_exts_dump_stats(skb, &prog->exts, &bpf_ext_map) < 0)
 334                 goto nla_put_failure;
 335
 336         return skb->len;
 337
 338 nla_put_failure:
 339         nla_nest_cancel(skb, nest);
 340         return -1;
 341 }
 342
 343 static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 344 {
 345         struct cls_bpf_head *head = tp->root;
 346         struct cls_bpf_prog *prog;
 347
 348         list_for_each_entry(prog, &head->plist, link) {
 349                 if (arg->count < arg->skip)
 350                         goto skip;
 351                 if (arg->fn(tp, (unsigned long) prog, arg) < 0) {
 352                         arg->stop = 1;
 353                         break;
 354                 }
 355 skip:
 356                 arg->count++;
 357         }
 358 }
 359
 360 static struct tcf_proto_ops cls_bpf_ops __read_mostly = {
 361         .kind           =       "bpf",
 362         .owner          =       THIS_MODULE,
 363         .classify       =       cls_bpf_classify,
 364         .init           =       cls_bpf_init,
 365         .destroy        =       cls_bpf_destroy,
 366         .get            =       cls_bpf_get,
 367         .put            =       cls_bpf_put,
 368         .change         =       cls_bpf_change,
 369         .delete         =       cls_bpf_delete,
 370         .walk           =       cls_bpf_walk,
 371         .dump           =       cls_bpf_dump,
 372 };
 373
 374 static int __init cls_bpf_init_mod(void)
 375 {
 376         return register_tcf_proto_ops(&cls_bpf_ops);
 377 }
 378
 379 static void __exit cls_bpf_exit_mod(void)
 380 {
 381         unregister_tcf_proto_ops(&cls_bpf_ops);
 382 }
 383
 384 module_init(cls_bpf_init_mod);
 385 module_exit(cls_bpf_exit_mod);