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Linux/net/sched/sch_dsmark.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /* net/sched/sch_dsmark.c - Differentiated Services field marker */
  3 
  4 /* Written 1998-2000 by Werner Almesberger, EPFL ICA */
  5 
  6 
  7 #include <linux/module.h>
  8 #include <linux/init.h>
  9 #include <linux/slab.h>
 10 #include <linux/types.h>
 11 #include <linux/string.h>
 12 #include <linux/errno.h>
 13 #include <linux/skbuff.h>
 14 #include <linux/rtnetlink.h>
 15 #include <linux/bitops.h>
 16 #include <net/pkt_sched.h>
 17 #include <net/pkt_cls.h>
 18 #include <net/dsfield.h>
 19 #include <net/inet_ecn.h>
 20 #include <asm/byteorder.h>
 21 
 22 /*
 23  * classid      class           marking
 24  * -------      -----           -------
 25  *   n/a          0             n/a
 26  *   x:0          1             use entry [0]
 27  *   ...         ...            ...
 28  *   x:y y>0     y+1            use entry [y]
 29  *   ...         ...            ...
 30  * x:indices-1  indices         use entry [indices-1]
 31  *   ...         ...            ...
 32  *   x:y         y+1            use entry [y & (indices-1)]
 33  *   ...         ...            ...
 34  * 0xffff       0x10000         use entry [indices-1]
 35  */
 36 
 37 
 38 #define NO_DEFAULT_INDEX        (1 << 16)
 39 
 40 struct mask_value {
 41         u8                      mask;
 42         u8                      value;
 43 };
 44 
 45 struct dsmark_qdisc_data {
 46         struct Qdisc            *q;
 47         struct tcf_proto __rcu  *filter_list;
 48         struct tcf_block        *block;
 49         struct mask_value       *mv;
 50         u16                     indices;
 51         u8                      set_tc_index;
 52         u32                     default_index;  /* index range is 0...0xffff */
 53 #define DSMARK_EMBEDDED_SZ      16
 54         struct mask_value       embedded[DSMARK_EMBEDDED_SZ];
 55 };
 56 
 57 static inline int dsmark_valid_index(struct dsmark_qdisc_data *p, u16 index)
 58 {
 59         return index <= p->indices && index > 0;
 60 }
 61 
 62 /* ------------------------- Class/flow operations ------------------------- */
 63 
 64 static int dsmark_graft(struct Qdisc *sch, unsigned long arg,
 65                         struct Qdisc *new, struct Qdisc **old,
 66                         struct netlink_ext_ack *extack)
 67 {
 68         struct dsmark_qdisc_data *p = qdisc_priv(sch);
 69 
 70         pr_debug("%s(sch %p,[qdisc %p],new %p,old %p)\n",
 71                  __func__, sch, p, new, old);
 72 
 73         if (new == NULL) {
 74                 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 75                                         sch->handle, NULL);
 76                 if (new == NULL)
 77                         new = &noop_qdisc;
 78         }
 79 
 80         *old = qdisc_replace(sch, new, &p->q);
 81         return 0;
 82 }
 83 
 84 static struct Qdisc *dsmark_leaf(struct Qdisc *sch, unsigned long arg)
 85 {
 86         struct dsmark_qdisc_data *p = qdisc_priv(sch);
 87         return p->q;
 88 }
 89 
 90 static unsigned long dsmark_find(struct Qdisc *sch, u32 classid)
 91 {
 92         return TC_H_MIN(classid) + 1;
 93 }
 94 
 95 static unsigned long dsmark_bind_filter(struct Qdisc *sch,
 96                                         unsigned long parent, u32 classid)
 97 {
 98         pr_debug("%s(sch %p,[qdisc %p],classid %x)\n",
 99                  __func__, sch, qdisc_priv(sch), classid);
100 
101         return dsmark_find(sch, classid);
102 }
103 
104 static void dsmark_unbind_filter(struct Qdisc *sch, unsigned long cl)
105 {
106 }
107 
108 static const struct nla_policy dsmark_policy[TCA_DSMARK_MAX + 1] = {
109         [TCA_DSMARK_INDICES]            = { .type = NLA_U16 },
110         [TCA_DSMARK_DEFAULT_INDEX]      = { .type = NLA_U16 },
111         [TCA_DSMARK_SET_TC_INDEX]       = { .type = NLA_FLAG },
112         [TCA_DSMARK_MASK]               = { .type = NLA_U8 },
113         [TCA_DSMARK_VALUE]              = { .type = NLA_U8 },
114 };
115 
116 static int dsmark_change(struct Qdisc *sch, u32 classid, u32 parent,
117                          struct nlattr **tca, unsigned long *arg,
118                          struct netlink_ext_ack *extack)
119 {
120         struct dsmark_qdisc_data *p = qdisc_priv(sch);
121         struct nlattr *opt = tca[TCA_OPTIONS];
122         struct nlattr *tb[TCA_DSMARK_MAX + 1];
123         int err = -EINVAL;
124 
125         pr_debug("%s(sch %p,[qdisc %p],classid %x,parent %x), arg 0x%lx\n",
126                  __func__, sch, p, classid, parent, *arg);
127 
128         if (!dsmark_valid_index(p, *arg)) {
129                 err = -ENOENT;
130                 goto errout;
131         }
132 
133         if (!opt)
134                 goto errout;
135 
136         err = nla_parse_nested_deprecated(tb, TCA_DSMARK_MAX, opt,
137                                           dsmark_policy, NULL);
138         if (err < 0)
139                 goto errout;
140 
141         if (tb[TCA_DSMARK_VALUE])
142                 p->mv[*arg - 1].value = nla_get_u8(tb[TCA_DSMARK_VALUE]);
143 
144         if (tb[TCA_DSMARK_MASK])
145                 p->mv[*arg - 1].mask = nla_get_u8(tb[TCA_DSMARK_MASK]);
146 
147         err = 0;
148 
149 errout:
150         return err;
151 }
152 
153 static int dsmark_delete(struct Qdisc *sch, unsigned long arg)
154 {
155         struct dsmark_qdisc_data *p = qdisc_priv(sch);
156 
157         if (!dsmark_valid_index(p, arg))
158                 return -EINVAL;
159 
160         p->mv[arg - 1].mask = 0xff;
161         p->mv[arg - 1].value = 0;
162 
163         return 0;
164 }
165 
166 static void dsmark_walk(struct Qdisc *sch, struct qdisc_walker *walker)
167 {
168         struct dsmark_qdisc_data *p = qdisc_priv(sch);
169         int i;
170 
171         pr_debug("%s(sch %p,[qdisc %p],walker %p)\n",
172                  __func__, sch, p, walker);
173 
174         if (walker->stop)
175                 return;
176 
177         for (i = 0; i < p->indices; i++) {
178                 if (p->mv[i].mask == 0xff && !p->mv[i].value)
179                         goto ignore;
180                 if (walker->count >= walker->skip) {
181                         if (walker->fn(sch, i + 1, walker) < 0) {
182                                 walker->stop = 1;
183                                 break;
184                         }
185                 }
186 ignore:
187                 walker->count++;
188         }
189 }
190 
191 static struct tcf_block *dsmark_tcf_block(struct Qdisc *sch, unsigned long cl,
192                                           struct netlink_ext_ack *extack)
193 {
194         struct dsmark_qdisc_data *p = qdisc_priv(sch);
195 
196         return p->block;
197 }
198 
199 /* --------------------------- Qdisc operations ---------------------------- */
200 
201 static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch,
202                           struct sk_buff **to_free)
203 {
204         unsigned int len = qdisc_pkt_len(skb);
205         struct dsmark_qdisc_data *p = qdisc_priv(sch);
206         int err;
207 
208         pr_debug("%s(skb %p,sch %p,[qdisc %p])\n", __func__, skb, sch, p);
209 
210         if (p->set_tc_index) {
211                 int wlen = skb_network_offset(skb);
212 
213                 switch (tc_skb_protocol(skb)) {
214                 case htons(ETH_P_IP):
215                         wlen += sizeof(struct iphdr);
216                         if (!pskb_may_pull(skb, wlen) ||
217                             skb_try_make_writable(skb, wlen))
218                                 goto drop;
219 
220                         skb->tc_index = ipv4_get_dsfield(ip_hdr(skb))
221                                 & ~INET_ECN_MASK;
222                         break;
223 
224                 case htons(ETH_P_IPV6):
225                         wlen += sizeof(struct ipv6hdr);
226                         if (!pskb_may_pull(skb, wlen) ||
227                             skb_try_make_writable(skb, wlen))
228                                 goto drop;
229 
230                         skb->tc_index = ipv6_get_dsfield(ipv6_hdr(skb))
231                                 & ~INET_ECN_MASK;
232                         break;
233                 default:
234                         skb->tc_index = 0;
235                         break;
236                 }
237         }
238 
239         if (TC_H_MAJ(skb->priority) == sch->handle)
240                 skb->tc_index = TC_H_MIN(skb->priority);
241         else {
242                 struct tcf_result res;
243                 struct tcf_proto *fl = rcu_dereference_bh(p->filter_list);
244                 int result = tcf_classify(skb, fl, &res, false);
245 
246                 pr_debug("result %d class 0x%04x\n", result, res.classid);
247 
248                 switch (result) {
249 #ifdef CONFIG_NET_CLS_ACT
250                 case TC_ACT_QUEUED:
251                 case TC_ACT_STOLEN:
252                 case TC_ACT_TRAP:
253                         __qdisc_drop(skb, to_free);
254                         return NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
255 
256                 case TC_ACT_SHOT:
257                         goto drop;
258 #endif
259                 case TC_ACT_OK:
260                         skb->tc_index = TC_H_MIN(res.classid);
261                         break;
262 
263                 default:
264                         if (p->default_index != NO_DEFAULT_INDEX)
265                                 skb->tc_index = p->default_index;
266                         break;
267                 }
268         }
269 
270         err = qdisc_enqueue(skb, p->q, to_free);
271         if (err != NET_XMIT_SUCCESS) {
272                 if (net_xmit_drop_count(err))
273                         qdisc_qstats_drop(sch);
274                 return err;
275         }
276 
277         sch->qstats.backlog += len;
278         sch->q.qlen++;
279 
280         return NET_XMIT_SUCCESS;
281 
282 drop:
283         qdisc_drop(skb, sch, to_free);
284         return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
285 }
286 
287 static struct sk_buff *dsmark_dequeue(struct Qdisc *sch)
288 {
289         struct dsmark_qdisc_data *p = qdisc_priv(sch);
290         struct sk_buff *skb;
291         u32 index;
292 
293         pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p);
294 
295         skb = qdisc_dequeue_peeked(p->q);
296         if (skb == NULL)
297                 return NULL;
298 
299         qdisc_bstats_update(sch, skb);
300         qdisc_qstats_backlog_dec(sch, skb);
301         sch->q.qlen--;
302 
303         index = skb->tc_index & (p->indices - 1);
304         pr_debug("index %d->%d\n", skb->tc_index, index);
305 
306         switch (tc_skb_protocol(skb)) {
307         case htons(ETH_P_IP):
308                 ipv4_change_dsfield(ip_hdr(skb), p->mv[index].mask,
309                                     p->mv[index].value);
310                         break;
311         case htons(ETH_P_IPV6):
312                 ipv6_change_dsfield(ipv6_hdr(skb), p->mv[index].mask,
313                                     p->mv[index].value);
314                         break;
315         default:
316                 /*
317                  * Only complain if a change was actually attempted.
318                  * This way, we can send non-IP traffic through dsmark
319                  * and don't need yet another qdisc as a bypass.
320                  */
321                 if (p->mv[index].mask != 0xff || p->mv[index].value)
322                         pr_warn("%s: unsupported protocol %d\n",
323                                 __func__, ntohs(tc_skb_protocol(skb)));
324                 break;
325         }
326 
327         return skb;
328 }
329 
330 static struct sk_buff *dsmark_peek(struct Qdisc *sch)
331 {
332         struct dsmark_qdisc_data *p = qdisc_priv(sch);
333 
334         pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p);
335 
336         return p->q->ops->peek(p->q);
337 }
338 
339 static int dsmark_init(struct Qdisc *sch, struct nlattr *opt,
340                        struct netlink_ext_ack *extack)
341 {
342         struct dsmark_qdisc_data *p = qdisc_priv(sch);
343         struct nlattr *tb[TCA_DSMARK_MAX + 1];
344         int err = -EINVAL;
345         u32 default_index = NO_DEFAULT_INDEX;
346         u16 indices;
347         int i;
348 
349         pr_debug("%s(sch %p,[qdisc %p],opt %p)\n", __func__, sch, p, opt);
350 
351         if (!opt)
352                 goto errout;
353 
354         err = tcf_block_get(&p->block, &p->filter_list, sch, extack);
355         if (err)
356                 return err;
357 
358         err = nla_parse_nested_deprecated(tb, TCA_DSMARK_MAX, opt,
359                                           dsmark_policy, NULL);
360         if (err < 0)
361                 goto errout;
362 
363         err = -EINVAL;
364         if (!tb[TCA_DSMARK_INDICES])
365                 goto errout;
366         indices = nla_get_u16(tb[TCA_DSMARK_INDICES]);
367 
368         if (hweight32(indices) != 1)
369                 goto errout;
370 
371         if (tb[TCA_DSMARK_DEFAULT_INDEX])
372                 default_index = nla_get_u16(tb[TCA_DSMARK_DEFAULT_INDEX]);
373 
374         if (indices <= DSMARK_EMBEDDED_SZ)
375                 p->mv = p->embedded;
376         else
377                 p->mv = kmalloc_array(indices, sizeof(*p->mv), GFP_KERNEL);
378         if (!p->mv) {
379                 err = -ENOMEM;
380                 goto errout;
381         }
382         for (i = 0; i < indices; i++) {
383                 p->mv[i].mask = 0xff;
384                 p->mv[i].value = 0;
385         }
386         p->indices = indices;
387         p->default_index = default_index;
388         p->set_tc_index = nla_get_flag(tb[TCA_DSMARK_SET_TC_INDEX]);
389 
390         p->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, sch->handle,
391                                  NULL);
392         if (p->q == NULL)
393                 p->q = &noop_qdisc;
394         else
395                 qdisc_hash_add(p->q, true);
396 
397         pr_debug("%s: qdisc %p\n", __func__, p->q);
398 
399         err = 0;
400 errout:
401         return err;
402 }
403 
404 static void dsmark_reset(struct Qdisc *sch)
405 {
406         struct dsmark_qdisc_data *p = qdisc_priv(sch);
407 
408         pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p);
409         qdisc_reset(p->q);
410         sch->qstats.backlog = 0;
411         sch->q.qlen = 0;
412 }
413 
414 static void dsmark_destroy(struct Qdisc *sch)
415 {
416         struct dsmark_qdisc_data *p = qdisc_priv(sch);
417 
418         pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p);
419 
420         tcf_block_put(p->block);
421         qdisc_put(p->q);
422         if (p->mv != p->embedded)
423                 kfree(p->mv);
424 }
425 
426 static int dsmark_dump_class(struct Qdisc *sch, unsigned long cl,
427                              struct sk_buff *skb, struct tcmsg *tcm)
428 {
429         struct dsmark_qdisc_data *p = qdisc_priv(sch);
430         struct nlattr *opts = NULL;
431 
432         pr_debug("%s(sch %p,[qdisc %p],class %ld\n", __func__, sch, p, cl);
433 
434         if (!dsmark_valid_index(p, cl))
435                 return -EINVAL;
436 
437         tcm->tcm_handle = TC_H_MAKE(TC_H_MAJ(sch->handle), cl - 1);
438         tcm->tcm_info = p->q->handle;
439 
440         opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
441         if (opts == NULL)
442                 goto nla_put_failure;
443         if (nla_put_u8(skb, TCA_DSMARK_MASK, p->mv[cl - 1].mask) ||
444             nla_put_u8(skb, TCA_DSMARK_VALUE, p->mv[cl - 1].value))
445                 goto nla_put_failure;
446 
447         return nla_nest_end(skb, opts);
448 
449 nla_put_failure:
450         nla_nest_cancel(skb, opts);
451         return -EMSGSIZE;
452 }
453 
454 static int dsmark_dump(struct Qdisc *sch, struct sk_buff *skb)
455 {
456         struct dsmark_qdisc_data *p = qdisc_priv(sch);
457         struct nlattr *opts = NULL;
458 
459         opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
460         if (opts == NULL)
461                 goto nla_put_failure;
462         if (nla_put_u16(skb, TCA_DSMARK_INDICES, p->indices))
463                 goto nla_put_failure;
464 
465         if (p->default_index != NO_DEFAULT_INDEX &&
466             nla_put_u16(skb, TCA_DSMARK_DEFAULT_INDEX, p->default_index))
467                 goto nla_put_failure;
468 
469         if (p->set_tc_index &&
470             nla_put_flag(skb, TCA_DSMARK_SET_TC_INDEX))
471                 goto nla_put_failure;
472 
473         return nla_nest_end(skb, opts);
474 
475 nla_put_failure:
476         nla_nest_cancel(skb, opts);
477         return -EMSGSIZE;
478 }
479 
480 static const struct Qdisc_class_ops dsmark_class_ops = {
481         .graft          =       dsmark_graft,
482         .leaf           =       dsmark_leaf,
483         .find           =       dsmark_find,
484         .change         =       dsmark_change,
485         .delete         =       dsmark_delete,
486         .walk           =       dsmark_walk,
487         .tcf_block      =       dsmark_tcf_block,
488         .bind_tcf       =       dsmark_bind_filter,
489         .unbind_tcf     =       dsmark_unbind_filter,
490         .dump           =       dsmark_dump_class,
491 };
492 
493 static struct Qdisc_ops dsmark_qdisc_ops __read_mostly = {
494         .next           =       NULL,
495         .cl_ops         =       &dsmark_class_ops,
496         .id             =       "dsmark",
497         .priv_size      =       sizeof(struct dsmark_qdisc_data),
498         .enqueue        =       dsmark_enqueue,
499         .dequeue        =       dsmark_dequeue,
500         .peek           =       dsmark_peek,
501         .init           =       dsmark_init,
502         .reset          =       dsmark_reset,
503         .destroy        =       dsmark_destroy,
504         .change         =       NULL,
505         .dump           =       dsmark_dump,
506         .owner          =       THIS_MODULE,
507 };
508 
509 static int __init dsmark_module_init(void)
510 {
511         return register_qdisc(&dsmark_qdisc_ops);
512 }
513 
514 static void __exit dsmark_module_exit(void)
515 {
516         unregister_qdisc(&dsmark_qdisc_ops);
517 }
518 
519 module_init(dsmark_module_init)
520 module_exit(dsmark_module_exit)
521 
522 MODULE_LICENSE("GPL");
523 

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