/* * Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014 Nicira, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include #include "classifier.h" #include "classifier-private.h" #include #include #include "byte-order.h" #include "dynamic-string.h" #include "odp-util.h" #include "ofp-util.h" #include "packets.h" #include "util.h" #include "openvswitch/vlog.h" VLOG_DEFINE_THIS_MODULE(classifier); struct trie_ctx; /* Ports trie depends on both ports sharing the same ovs_be32. */ #define TP_PORTS_OFS32 (offsetof(struct flow, tp_src) / 4) BUILD_ASSERT_DECL(TP_PORTS_OFS32 == offsetof(struct flow, tp_dst) / 4); BUILD_ASSERT_DECL(TP_PORTS_OFS32 % 2 == 0); #define TP_PORTS_OFS64 (TP_PORTS_OFS32 / 2) static struct cls_match * cls_match_alloc(const struct cls_rule *rule) { int count = count_1bits(rule->match.flow.map); struct cls_match *cls_match = xmalloc(sizeof *cls_match - sizeof cls_match->flow.inline_values + MINIFLOW_VALUES_SIZE(count)); rculist_init(&cls_match->list); *CONST_CAST(const struct cls_rule **, &cls_match->cls_rule) = rule; *CONST_CAST(int *, &cls_match->priority) = rule->priority; miniflow_clone_inline(CONST_CAST(struct miniflow *, &cls_match->flow), &rule->match.flow, count); return cls_match; } static struct cls_subtable *find_subtable(const struct classifier *cls, const struct minimask *); static struct cls_subtable *insert_subtable(struct classifier *cls, const struct minimask *); static void destroy_subtable(struct classifier *cls, struct cls_subtable *); static const struct cls_match *find_match_wc(const struct cls_subtable *, const struct flow *, struct trie_ctx *, unsigned int n_tries, struct flow_wildcards *); static struct cls_match *find_equal(const struct cls_subtable *, const struct miniflow *, uint32_t hash); static inline const struct cls_match * next_rule_in_list__(const struct cls_match *rule) { const struct cls_match *next = NULL; next = OBJECT_CONTAINING(rculist_next(&rule->list), next, list); return next; } static inline const struct cls_match * next_rule_in_list(const struct cls_match *rule) { const struct cls_match *next = next_rule_in_list__(rule); return next->priority < rule->priority ? next : NULL; } static inline struct cls_match * next_rule_in_list_protected__(struct cls_match *rule) { struct cls_match *next = NULL; next = OBJECT_CONTAINING(rculist_next_protected(&rule->list), next, list); return next; } static inline struct cls_match * next_rule_in_list_protected(struct cls_match *rule) { struct cls_match *next = next_rule_in_list_protected__(rule); return next->priority < rule->priority ? next : NULL; } /* Iterates RULE over HEAD and all of the cls_rules on HEAD->list. */ #define FOR_EACH_RULE_IN_LIST(RULE, HEAD) \ for ((RULE) = (HEAD); (RULE) != NULL; (RULE) = next_rule_in_list(RULE)) #define FOR_EACH_RULE_IN_LIST_PROTECTED(RULE, HEAD) \ for ((RULE) = (HEAD); (RULE) != NULL; \ (RULE) = next_rule_in_list_protected(RULE)) static unsigned int minimask_get_prefix_len(const struct minimask *, const struct mf_field *); static void trie_init(struct classifier *cls, int trie_idx, const struct mf_field *); static unsigned int trie_lookup(const struct cls_trie *, const struct flow *, union mf_value *plens); static unsigned int trie_lookup_value(const rcu_trie_ptr *, const ovs_be32 value[], ovs_be32 plens[], unsigned int value_bits); static void trie_destroy(rcu_trie_ptr *); static void trie_insert(struct cls_trie *, const struct cls_rule *, int mlen); static void trie_insert_prefix(rcu_trie_ptr *, const ovs_be32 *prefix, int mlen); static void trie_remove(struct cls_trie *, const struct cls_rule *, int mlen); static void trie_remove_prefix(rcu_trie_ptr *, const ovs_be32 *prefix, int mlen); static void mask_set_prefix_bits(struct flow_wildcards *, uint8_t be32ofs, unsigned int n_bits); static bool mask_prefix_bits_set(const struct flow_wildcards *, uint8_t be32ofs, unsigned int n_bits); /* cls_rule. */ static inline void cls_rule_init__(struct cls_rule *rule, unsigned int priority) { rculist_init(&rule->node); rule->priority = priority; rule->cls_match = NULL; } /* Initializes 'rule' to match packets specified by 'match' at the given * 'priority'. 'match' must satisfy the invariant described in the comment at * the definition of struct match. * * The caller must eventually destroy 'rule' with cls_rule_destroy(). * * Clients should not use priority INT_MIN. (OpenFlow uses priorities between * 0 and UINT16_MAX, inclusive.) */ void cls_rule_init(struct cls_rule *rule, const struct match *match, int priority) { cls_rule_init__(rule, priority); minimatch_init(&rule->match, match); } /* Same as cls_rule_init() for initialization from a "struct minimatch". */ void cls_rule_init_from_minimatch(struct cls_rule *rule, const struct minimatch *match, int priority) { cls_rule_init__(rule, priority); minimatch_clone(&rule->match, match); } /* Initializes 'dst' as a copy of 'src'. * * The caller must eventually destroy 'dst' with cls_rule_destroy(). */ void cls_rule_clone(struct cls_rule *dst, const struct cls_rule *src) { cls_rule_init__(dst, src->priority); minimatch_clone(&dst->match, &src->match); } /* Initializes 'dst' with the data in 'src', destroying 'src'. * 'src' must be a cls_rule NOT in a classifier. * * The caller must eventually destroy 'dst' with cls_rule_destroy(). */ void cls_rule_move(struct cls_rule *dst, struct cls_rule *src) { ovs_assert(!src->cls_match); /* Must not be in a classifier. */ cls_rule_init__(dst, src->priority); minimatch_move(&dst->match, &src->match); } /* Frees memory referenced by 'rule'. Doesn't free 'rule' itself (it's * normally embedded into a larger structure). * * ('rule' must not currently be in a classifier.) */ void cls_rule_destroy(struct cls_rule *rule) { ovs_assert(!rule->cls_match); /* Must not be in a classifier. */ /* Check that the rule has been properly removed from the classifier and * that the destruction only happens after the RCU grace period, or that * the rule was never inserted to the classifier in the first place. */ ovs_assert(rculist_next_protected(&rule->node) == RCULIST_POISON || rculist_is_empty(&rule->node)); minimatch_destroy(&rule->match); } /* Returns true if 'a' and 'b' match the same packets at the same priority, * false if they differ in some way. */ bool cls_rule_equal(const struct cls_rule *a, const struct cls_rule *b) { return a->priority == b->priority && minimatch_equal(&a->match, &b->match); } /* Returns a hash value for 'rule', folding in 'basis'. */ uint32_t cls_rule_hash(const struct cls_rule *rule, uint32_t basis) { return minimatch_hash(&rule->match, hash_int(rule->priority, basis)); } /* Appends a string describing 'rule' to 's'. */ void cls_rule_format(const struct cls_rule *rule, struct ds *s) { minimatch_format(&rule->match, s, rule->priority); } /* Returns true if 'rule' matches every packet, false otherwise. */ bool cls_rule_is_catchall(const struct cls_rule *rule) { return minimask_is_catchall(&rule->match.mask); } /* Initializes 'cls' as a classifier that initially contains no classification * rules. */ void classifier_init(struct classifier *cls, const uint8_t *flow_segments) { cls->n_rules = 0; cmap_init(&cls->subtables_map); pvector_init(&cls->subtables); cmap_init(&cls->partitions); cls->n_flow_segments = 0; if (flow_segments) { while (cls->n_flow_segments < CLS_MAX_INDICES && *flow_segments < FLOW_U64S) { cls->flow_segments[cls->n_flow_segments++] = *flow_segments++; } } cls->n_tries = 0; for (int i = 0; i < CLS_MAX_TRIES; i++) { trie_init(cls, i, NULL); } cls->publish = true; } /* Destroys 'cls'. Rules within 'cls', if any, are not freed; this is the * caller's responsibility. * May only be called after all the readers have been terminated. */ void classifier_destroy(struct classifier *cls) { if (cls) { struct cls_partition *partition; struct cls_subtable *subtable; int i; for (i = 0; i < cls->n_tries; i++) { trie_destroy(&cls->tries[i].root); } CMAP_FOR_EACH (subtable, cmap_node, &cls->subtables_map) { destroy_subtable(cls, subtable); } cmap_destroy(&cls->subtables_map); CMAP_FOR_EACH (partition, cmap_node, &cls->partitions) { ovsrcu_postpone(free, partition); } cmap_destroy(&cls->partitions); pvector_destroy(&cls->subtables); } } /* Set the fields for which prefix lookup should be performed. */ bool classifier_set_prefix_fields(struct classifier *cls, const enum mf_field_id *trie_fields, unsigned int n_fields) { const struct mf_field * new_fields[CLS_MAX_TRIES]; struct mf_bitmap fields = MF_BITMAP_INITIALIZER; int i, n_tries = 0; bool changed = false; for (i = 0; i < n_fields && n_tries < CLS_MAX_TRIES; i++) { const struct mf_field *field = mf_from_id(trie_fields[i]); if (field->flow_be32ofs < 0 || field->n_bits % 32) { /* Incompatible field. This is the only place where we * enforce these requirements, but the rest of the trie code * depends on the flow_be32ofs to be non-negative and the * field length to be a multiple of 32 bits. */ continue; } if (bitmap_is_set(fields.bm, trie_fields[i])) { /* Duplicate field, there is no need to build more than * one index for any one field. */ continue; } bitmap_set1(fields.bm, trie_fields[i]); new_fields[n_tries] = NULL; if (n_tries >= cls->n_tries || field != cls->tries[n_tries].field) { new_fields[n_tries] = field; changed = true; } n_tries++; } if (changed || n_tries < cls->n_tries) { struct cls_subtable *subtable; /* Trie configuration needs to change. Disable trie lookups * for the tries that are changing and wait all the current readers * with the old configuration to be done. */ changed = false; CMAP_FOR_EACH (subtable, cmap_node, &cls->subtables_map) { for (i = 0; i < cls->n_tries; i++) { if ((i < n_tries && new_fields[i]) || i >= n_tries) { if (subtable->trie_plen[i]) { subtable->trie_plen[i] = 0; changed = true; } } } } /* Synchronize if any readers were using tries. The readers may * temporarily function without the trie lookup based optimizations. */ if (changed) { /* ovsrcu_synchronize() functions as a memory barrier, so it does * not matter that subtable->trie_plen is not atomic. */ ovsrcu_synchronize(); } /* Now set up the tries. */ for (i = 0; i < n_tries; i++) { if (new_fields[i]) { trie_init(cls, i, new_fields[i]); } } /* Destroy the rest, if any. */ for (; i < cls->n_tries; i++) { trie_init(cls, i, NULL); } cls->n_tries = n_tries; return true; } return false; /* No change. */ } static void trie_init(struct classifier *cls, int trie_idx, const struct mf_field *field) { struct cls_trie *trie = &cls->tries[trie_idx]; struct cls_subtable *subtable; if (trie_idx < cls->n_tries) { trie_destroy(&trie->root); } else { ovsrcu_set_hidden(&trie->root, NULL); } trie->field = field; /* Add existing rules to the new trie. */ CMAP_FOR_EACH (subtable, cmap_node, &cls->subtables_map) { unsigned int plen; plen = field ? minimask_get_prefix_len(&subtable->mask, field) : 0; if (plen) { struct cls_match *head; CMAP_FOR_EACH (head, cmap_node, &subtable->rules) { trie_insert(trie, head->cls_rule, plen); } } /* Initialize subtable's prefix length on this field. This will * allow readers to use the trie. */ atomic_thread_fence(memory_order_release); subtable->trie_plen[trie_idx] = plen; } } /* Returns true if 'cls' contains no classification rules, false otherwise. * Checking the cmap requires no locking. */ bool classifier_is_empty(const struct classifier *cls) { return cmap_is_empty(&cls->subtables_map); } /* Returns the number of rules in 'cls'. */ int classifier_count(const struct classifier *cls) { /* n_rules is an int, so in the presence of concurrent writers this will * return either the old or a new value. */ return cls->n_rules; } static uint32_t hash_metadata(ovs_be64 metadata) { return hash_uint64((OVS_FORCE uint64_t) metadata); } static struct cls_partition * find_partition(const struct classifier *cls, ovs_be64 metadata, uint32_t hash) { struct cls_partition *partition; CMAP_FOR_EACH_WITH_HASH (partition, cmap_node, hash, &cls->partitions) { if (partition->metadata == metadata) { return partition; } } return NULL; } static struct cls_partition * create_partition(struct classifier *cls, struct cls_subtable *subtable, ovs_be64 metadata) { uint32_t hash = hash_metadata(metadata); struct cls_partition *partition = find_partition(cls, metadata, hash); if (!partition) { partition = xmalloc(sizeof *partition); partition->metadata = metadata; partition->tags = 0; tag_tracker_init(&partition->tracker); cmap_insert(&cls->partitions, &partition->cmap_node, hash); } tag_tracker_add(&partition->tracker, &partition->tags, subtable->tag); return partition; } static inline ovs_be32 minimatch_get_ports(const struct minimatch *match) { /* Could optimize to use the same map if needed for fast path. */ return MINIFLOW_GET_BE32(&match->flow, tp_src) & MINIFLOW_GET_BE32(&match->mask.masks, tp_src); } static void subtable_replace_head_rule(struct classifier *cls OVS_UNUSED, struct cls_subtable *subtable, struct cls_match *head, struct cls_match *new, uint32_t hash, uint32_t ihash[CLS_MAX_INDICES]) { /* Rule's data is already in the tries. */ new->partition = head->partition; /* Steal partition, if any. */ head->partition = NULL; for (int i = 0; i < subtable->n_indices; i++) { cmap_replace(&subtable->indices[i], &head->index_nodes[i], &new->index_nodes[i], ihash[i]); } cmap_replace(&subtable->rules, &head->cmap_node, &new->cmap_node, hash); } /* Inserts 'rule' into 'cls'. Until 'rule' is removed from 'cls', the caller * must not modify or free it. * * If 'cls' already contains an identical rule (including wildcards, values of * fixed fields, and priority), replaces the old rule by 'rule' and returns the * rule that was replaced. The caller takes ownership of the returned rule and * is thus responsible for destroying it with cls_rule_destroy(), after RCU * grace period has passed (see ovsrcu_postpone()). * * Returns NULL if 'cls' does not contain a rule with an identical key, after * inserting the new rule. In this case, no rules are displaced by the new * rule, even rules that cannot have any effect because the new rule matches a * superset of their flows and has higher priority. */ const struct cls_rule * classifier_replace(struct classifier *cls, const struct cls_rule *rule) { struct cls_match *new = cls_match_alloc(rule); struct cls_subtable *subtable; uint32_t ihash[CLS_MAX_INDICES]; uint8_t prev_be64ofs = 0; struct cls_match *head; size_t n_rules = 0; uint32_t basis; uint32_t hash; int i; CONST_CAST(struct cls_rule *, rule)->cls_match = new; subtable = find_subtable(cls, &rule->match.mask); if (!subtable) { subtable = insert_subtable(cls, &rule->match.mask); } /* Compute hashes in segments. */ basis = 0; for (i = 0; i < subtable->n_indices; i++) { ihash[i] = minimatch_hash_range(&rule->match, prev_be64ofs, subtable->index_ofs[i], &basis); prev_be64ofs = subtable->index_ofs[i]; } hash = minimatch_hash_range(&rule->match, prev_be64ofs, FLOW_U64S, &basis); head = find_equal(subtable, &rule->match.flow, hash); if (!head) { /* Add rule to tries. * * Concurrent readers might miss seeing the rule until this update, * which might require being fixed up by revalidation later. */ for (i = 0; i < cls->n_tries; i++) { if (subtable->trie_plen[i]) { trie_insert(&cls->tries[i], rule, subtable->trie_plen[i]); } } /* Add rule to ports trie. */ if (subtable->ports_mask_len) { /* We mask the value to be inserted to always have the wildcarded * bits in known (zero) state, so we can include them in comparison * and they will always match (== their original value does not * matter). */ ovs_be32 masked_ports = minimatch_get_ports(&rule->match); trie_insert_prefix(&subtable->ports_trie, &masked_ports, subtable->ports_mask_len); } /* Add rule to partitions. * * Concurrent readers might miss seeing the rule until this update, * which might require being fixed up by revalidation later. */ new->partition = NULL; if (minimask_get_metadata_mask(&rule->match.mask) == OVS_BE64_MAX) { ovs_be64 metadata = miniflow_get_metadata(&rule->match.flow); new->partition = create_partition(cls, subtable, metadata); } /* Make rule visible to lookups. */ /* Add new node to segment indices. * * Readers may find the rule in the indices before the rule is visible * in the subtables 'rules' map. This may result in us losing the * opportunity to quit lookups earlier, resulting in sub-optimal * wildcarding. This will be fixed later by revalidation (always * scheduled after flow table changes). */ for (i = 0; i < subtable->n_indices; i++) { cmap_insert(&subtable->indices[i], &new->index_nodes[i], ihash[i]); } n_rules = cmap_insert(&subtable->rules, &new->cmap_node, hash); } else { /* Equal rules exist in the classifier already. */ struct cls_match *iter; /* Scan the list for the insertion point that will keep the list in * order of decreasing priority. */ FOR_EACH_RULE_IN_LIST_PROTECTED (iter, head) { if (rule->priority >= iter->priority) { break; } } /* 'iter' now at the insertion point or NULL it at end. */ if (iter) { struct cls_rule *old; if (rule->priority == iter->priority) { rculist_replace(&new->list, &iter->list); old = CONST_CAST(struct cls_rule *, iter->cls_rule); } else { rculist_insert(&iter->list, &new->list); old = NULL; } /* Replace the existing head in data structures, if rule is the new * head. */ if (iter == head) { subtable_replace_head_rule(cls, subtable, head, new, hash, ihash); } if (old) { ovsrcu_postpone(free, iter); old->cls_match = NULL; /* No change in subtable's max priority or max count. */ /* Make rule visible to iterators. */ rculist_replace(CONST_CAST(struct rculist *, &rule->node), &old->node); /* Return displaced rule. Caller is responsible for keeping it * around until all threads quiesce. */ return old; } } else { rculist_push_back(&head->list, &new->list); } } /* Make rule visible to iterators. */ rculist_push_back(&subtable->rules_list, CONST_CAST(struct rculist *, &rule->node)); /* Rule was added, not replaced. Update 'subtable's 'max_priority' and * 'max_count', if necessary. * * The rule was already inserted, but concurrent readers may not see the * rule yet as the subtables vector is not updated yet. This will have to * be fixed by revalidation later. */ if (n_rules == 1) { subtable->max_priority = rule->priority; subtable->max_count = 1; pvector_insert(&cls->subtables, subtable, rule->priority); } else if (rule->priority == subtable->max_priority) { ++subtable->max_count; } else if (rule->priority > subtable->max_priority) { subtable->max_priority = rule->priority; subtable->max_count = 1; pvector_change_priority(&cls->subtables, subtable, rule->priority); } /* Nothing was replaced. */ cls->n_rules++; if (cls->publish) { pvector_publish(&cls->subtables); } return NULL; } /* Inserts 'rule' into 'cls'. Until 'rule' is removed from 'cls', the caller * must not modify or free it. * * 'cls' must not contain an identical rule (including wildcards, values of * fixed fields, and priority). Use classifier_find_rule_exactly() to find * such a rule. */ void classifier_insert(struct classifier *cls, const struct cls_rule *rule) { const struct cls_rule *displaced_rule = classifier_replace(cls, rule); ovs_assert(!displaced_rule); } /* Removes 'rule' from 'cls'. It is the caller's responsibility to destroy * 'rule' with cls_rule_destroy(), freeing the memory block in which 'rule' * resides, etc., as necessary. * * Does nothing if 'rule' has been already removed, or was never inserted. * * Returns the removed rule, or NULL, if it was already removed. */ const struct cls_rule * classifier_remove(struct classifier *cls, const struct cls_rule *rule) { struct cls_partition *partition; struct cls_match *cls_match; struct cls_subtable *subtable; struct cls_match *prev; struct cls_match *next; int i; uint32_t basis = 0, hash, ihash[CLS_MAX_INDICES]; uint8_t prev_be64ofs = 0; size_t n_rules; cls_match = rule->cls_match; if (!cls_match) { return NULL; } /* Mark as removed. */ CONST_CAST(struct cls_rule *, rule)->cls_match = NULL; /* Remove 'rule' from the subtable's rules list. */ rculist_remove(CONST_CAST(struct rculist *, &rule->node)); INIT_CONTAINER(prev, rculist_back_protected(&cls_match->list), list); INIT_CONTAINER(next, rculist_next(&cls_match->list), list); /* Remove from the list of equal rules. */ rculist_remove(&cls_match->list); /* Check if this is NOT a head rule. */ if (prev->priority > rule->priority) { /* Not the highest priority rule, no need to check subtable's * 'max_priority'. */ goto free; } subtable = find_subtable(cls, &rule->match.mask); ovs_assert(subtable); for (i = 0; i < subtable->n_indices; i++) { ihash[i] = minimatch_hash_range(&rule->match, prev_be64ofs, subtable->index_ofs[i], &basis); prev_be64ofs = subtable->index_ofs[i]; } hash = minimatch_hash_range(&rule->match, prev_be64ofs, FLOW_U64S, &basis); /* Head rule. Check if 'next' is an identical, lower-priority rule that * will replace 'rule' in the data structures. */ if (next->priority < rule->priority) { subtable_replace_head_rule(cls, subtable, cls_match, next, hash, ihash); goto check_priority; } /* 'rule' is last of the kind in the classifier, must remove from all the * data structures. */ if (subtable->ports_mask_len) { ovs_be32 masked_ports = minimatch_get_ports(&rule->match); trie_remove_prefix(&subtable->ports_trie, &masked_ports, subtable->ports_mask_len); } for (i = 0; i < cls->n_tries; i++) { if (subtable->trie_plen[i]) { trie_remove(&cls->tries[i], rule, subtable->trie_plen[i]); } } /* Remove rule node from indices. */ for (i = 0; i < subtable->n_indices; i++) { cmap_remove(&subtable->indices[i], &cls_match->index_nodes[i], ihash[i]); } n_rules = cmap_remove(&subtable->rules, &cls_match->cmap_node, hash); partition = cls_match->partition; if (partition) { tag_tracker_subtract(&partition->tracker, &partition->tags, subtable->tag); if (!partition->tags) { cmap_remove(&cls->partitions, &partition->cmap_node, hash_metadata(partition->metadata)); ovsrcu_postpone(free, partition); } } if (n_rules == 0) { destroy_subtable(cls, subtable); } else { check_priority: if (subtable->max_priority == rule->priority && --subtable->max_count == 0) { /* Find the new 'max_priority' and 'max_count'. */ struct cls_match *head; int max_priority = INT_MIN; CMAP_FOR_EACH (head, cmap_node, &subtable->rules) { if (head->priority > max_priority) { max_priority = head->priority; subtable->max_count = 1; } else if (head->priority == max_priority) { ++subtable->max_count; } } subtable->max_priority = max_priority; pvector_change_priority(&cls->subtables, subtable, max_priority); } } if (cls->publish) { pvector_publish(&cls->subtables); } free: ovsrcu_postpone(free, cls_match); cls->n_rules--; return rule; } /* Prefix tree context. Valid when 'lookup_done' is true. Can skip all * subtables which have a prefix match on the trie field, but whose prefix * length is not indicated in 'match_plens'. For example, a subtable that * has a 8-bit trie field prefix match can be skipped if * !be_get_bit_at(&match_plens, 8 - 1). If skipped, 'maskbits' prefix bits * must be unwildcarded to make datapath flow only match packets it should. */ struct trie_ctx { const struct cls_trie *trie; bool lookup_done; /* Status of the lookup. */ uint8_t be32ofs; /* U32 offset of the field in question. */ unsigned int maskbits; /* Prefix length needed to avoid false matches. */ union mf_value match_plens; /* Bitmask of prefix lengths with possible * matches. */ }; static void trie_ctx_init(struct trie_ctx *ctx, const struct cls_trie *trie) { ctx->trie = trie; ctx->be32ofs = trie->field->flow_be32ofs; ctx->lookup_done = false; } /* Finds and returns the highest-priority rule in 'cls' that matches 'flow'. * Returns a null pointer if no rules in 'cls' match 'flow'. If multiple rules * of equal priority match 'flow', returns one arbitrarily. * * If a rule is found and 'wc' is non-null, bitwise-OR's 'wc' with the * set of bits that were significant in the lookup. At some point * earlier, 'wc' should have been initialized (e.g., by * flow_wildcards_init_catchall()). * * 'flow' is non-const to allow for temporary modifications during the lookup. * Any changes are restored before returning. */ const struct cls_rule * classifier_lookup(const struct classifier *cls, struct flow *flow, struct flow_wildcards *wc) { const struct cls_partition *partition; tag_type tags; int best_priority = INT_MIN; const struct cls_match *best; struct trie_ctx trie_ctx[CLS_MAX_TRIES]; struct cls_subtable *subtable; /* Synchronize for cls->n_tries and subtable->trie_plen. They can change * when table configuration changes, which happens typically only on * startup. */ atomic_thread_fence(memory_order_acquire); /* Determine 'tags' such that, if 'subtable->tag' doesn't intersect them, * then 'flow' cannot possibly match in 'subtable': * * - If flow->metadata maps to a given 'partition', then we can use * 'tags' for 'partition->tags'. * * - If flow->metadata has no partition, then no rule in 'cls' has an * exact-match for flow->metadata. That means that we don't need to * search any subtable that includes flow->metadata in its mask. * * In either case, we always need to search any cls_subtables that do not * include flow->metadata in its mask. One way to do that would be to * check the "cls_subtable"s explicitly for that, but that would require an * extra branch per subtable. Instead, we mark such a cls_subtable's * 'tags' as TAG_ALL and make sure that 'tags' is never empty. This means * that 'tags' always intersects such a cls_subtable's 'tags', so we don't * need a special case. */ partition = (cmap_is_empty(&cls->partitions) ? NULL : find_partition(cls, flow->metadata, hash_metadata(flow->metadata))); tags = partition ? partition->tags : TAG_ARBITRARY; /* Initialize trie contexts for find_match_wc(). */ for (int i = 0; i < cls->n_tries; i++) { trie_ctx_init(&trie_ctx[i], &cls->tries[i]); } best = NULL; PVECTOR_FOR_EACH_PRIORITY(subtable, best_priority, 2, sizeof(struct cls_subtable), &cls->subtables) { const struct cls_match *rule; if (!tag_intersects(tags, subtable->tag)) { continue; } rule = find_match_wc(subtable, flow, trie_ctx, cls->n_tries, wc); if (rule && rule->priority > best_priority) { best_priority = rule->priority; best = rule; } } return best ? best->cls_rule : NULL; } /* Finds and returns a rule in 'cls' with exactly the same priority and * matching criteria as 'target'. Returns a null pointer if 'cls' doesn't * contain an exact match. */ const struct cls_rule * classifier_find_rule_exactly(const struct classifier *cls, const struct cls_rule *target) { const struct cls_match *head, *rule; const struct cls_subtable *subtable; subtable = find_subtable(cls, &target->match.mask); if (!subtable) { return NULL; } head = find_equal(subtable, &target->match.flow, miniflow_hash_in_minimask(&target->match.flow, &target->match.mask, 0)); if (!head) { return NULL; } FOR_EACH_RULE_IN_LIST (rule, head) { if (target->priority >= rule->priority) { return target->priority == rule->priority ? rule->cls_rule : NULL; } } return NULL; } /* Finds and returns a rule in 'cls' with priority 'priority' and exactly the * same matching criteria as 'target'. Returns a null pointer if 'cls' doesn't * contain an exact match. */ const struct cls_rule * classifier_find_match_exactly(const struct classifier *cls, const struct match *target, int priority) { const struct cls_rule *retval; struct cls_rule cr; cls_rule_init(&cr, target, priority); retval = classifier_find_rule_exactly(cls, &cr); cls_rule_destroy(&cr); return retval; } /* Checks if 'target' would overlap any other rule in 'cls'. Two rules are * considered to overlap if both rules have the same priority and a packet * could match both. * * A trivial example of overlapping rules is two rules matching disjoint sets * of fields. E.g., if one rule matches only on port number, while another only * on dl_type, any packet from that specific port and with that specific * dl_type could match both, if the rules also have the same priority. */ bool classifier_rule_overlaps(const struct classifier *cls, const struct cls_rule *target) { struct cls_subtable *subtable; /* Iterate subtables in the descending max priority order. */ PVECTOR_FOR_EACH_PRIORITY (subtable, target->priority - 1, 2, sizeof(struct cls_subtable), &cls->subtables) { uint64_t storage[FLOW_U64S]; struct minimask mask; const struct cls_rule *rule; minimask_combine(&mask, &target->match.mask, &subtable->mask, storage); RCULIST_FOR_EACH (rule, node, &subtable->rules_list) { if (rule->priority == target->priority && miniflow_equal_in_minimask(&target->match.flow, &rule->match.flow, &mask)) { return true; } } } return false; } /* Returns true if 'rule' exactly matches 'criteria' or if 'rule' is more * specific than 'criteria'. That is, 'rule' matches 'criteria' and this * function returns true if, for every field: * * - 'criteria' and 'rule' specify the same (non-wildcarded) value for the * field, or * * - 'criteria' wildcards the field, * * Conversely, 'rule' does not match 'criteria' and this function returns false * if, for at least one field: * * - 'criteria' and 'rule' specify different values for the field, or * * - 'criteria' specifies a value for the field but 'rule' wildcards it. * * Equivalently, the truth table for whether a field matches is: * * rule * * c wildcard exact * r +---------+---------+ * i wild | yes | yes | * t card | | | * e +---------+---------+ * r exact | no |if values| * i | |are equal| * a +---------+---------+ * * This is the matching rule used by OpenFlow 1.0 non-strict OFPT_FLOW_MOD * commands and by OpenFlow 1.0 aggregate and flow stats. * * Ignores rule->priority. */ bool cls_rule_is_loose_match(const struct cls_rule *rule, const struct minimatch *criteria) { return (!minimask_has_extra(&rule->match.mask, &criteria->mask) && miniflow_equal_in_minimask(&rule->match.flow, &criteria->flow, &criteria->mask)); } /* Iteration. */ static bool rule_matches(const struct cls_rule *rule, const struct cls_rule *target) { return (!target || miniflow_equal_in_minimask(&rule->match.flow, &target->match.flow, &target->match.mask)); } static const struct cls_rule * search_subtable(const struct cls_subtable *subtable, struct cls_cursor *cursor) { if (!cursor->target || !minimask_has_extra(&subtable->mask, &cursor->target->match.mask)) { const struct cls_rule *rule; RCULIST_FOR_EACH (rule, node, &subtable->rules_list) { if (rule_matches(rule, cursor->target)) { return rule; } } } return NULL; } /* Initializes 'cursor' for iterating through rules in 'cls', and returns the * first matching cls_rule via '*pnode', or NULL if there are no matches. * * - If 'target' is null, the cursor will visit every rule in 'cls'. * * - If 'target' is nonnull, the cursor will visit each 'rule' in 'cls' * such that cls_rule_is_loose_match(rule, target) returns true. * * Ignores target->priority. */ struct cls_cursor cls_cursor_start(const struct classifier *cls, const struct cls_rule *target) { struct cls_cursor cursor; struct cls_subtable *subtable; cursor.cls = cls; cursor.target = target && !cls_rule_is_catchall(target) ? target : NULL; cursor.rule = NULL; /* Find first rule. */ PVECTOR_CURSOR_FOR_EACH (subtable, &cursor.subtables, &cursor.cls->subtables) { const struct cls_rule *rule = search_subtable(subtable, &cursor); if (rule) { cursor.subtable = subtable; cursor.rule = rule; break; } } return cursor; } static const struct cls_rule * cls_cursor_next(struct cls_cursor *cursor) { const struct cls_rule *rule; const struct cls_subtable *subtable; rule = cursor->rule; subtable = cursor->subtable; RCULIST_FOR_EACH_CONTINUE (rule, node, &subtable->rules_list) { if (rule_matches(rule, cursor->target)) { return rule; } } PVECTOR_CURSOR_FOR_EACH_CONTINUE (subtable, &cursor->subtables) { rule = search_subtable(subtable, cursor); if (rule) { cursor->subtable = subtable; return rule; } } return NULL; } /* Sets 'cursor->rule' to the next matching cls_rule in 'cursor''s iteration, * or to null if all matching rules have been visited. */ void cls_cursor_advance(struct cls_cursor *cursor) { cursor->rule = cls_cursor_next(cursor); } static struct cls_subtable * find_subtable(const struct classifier *cls, const struct minimask *mask) { struct cls_subtable *subtable; CMAP_FOR_EACH_WITH_HASH (subtable, cmap_node, minimask_hash(mask, 0), &cls->subtables_map) { if (minimask_equal(mask, &subtable->mask)) { return subtable; } } return NULL; } /* The new subtable will be visible to the readers only after this. */ static struct cls_subtable * insert_subtable(struct classifier *cls, const struct minimask *mask) { uint32_t hash = minimask_hash(mask, 0); struct cls_subtable *subtable; int i, index = 0; struct flow_wildcards old, new; uint8_t prev; int count = count_1bits(mask->masks.map); subtable = xzalloc(sizeof *subtable - sizeof mask->masks.inline_values + MINIFLOW_VALUES_SIZE(count)); cmap_init(&subtable->rules); miniflow_clone_inline(CONST_CAST(struct miniflow *, &subtable->mask.masks), &mask->masks, count); /* Init indices for segmented lookup, if any. */ flow_wildcards_init_catchall(&new); old = new; prev = 0; for (i = 0; i < cls->n_flow_segments; i++) { flow_wildcards_fold_minimask_range(&new, mask, prev, cls->flow_segments[i]); /* Add an index if it adds mask bits. */ if (!flow_wildcards_equal(&new, &old)) { cmap_init(&subtable->indices[index]); *CONST_CAST(uint8_t *, &subtable->index_ofs[index]) = cls->flow_segments[i]; index++; old = new; } prev = cls->flow_segments[i]; } /* Check if the rest of the subtable's mask adds any bits, * and remove the last index if it doesn't. */ if (index > 0) { flow_wildcards_fold_minimask_range(&new, mask, prev, FLOW_U64S); if (flow_wildcards_equal(&new, &old)) { --index; *CONST_CAST(uint8_t *, &subtable->index_ofs[index]) = 0; cmap_destroy(&subtable->indices[index]); } } *CONST_CAST(uint8_t *, &subtable->n_indices) = index; *CONST_CAST(tag_type *, &subtable->tag) = (minimask_get_metadata_mask(mask) == OVS_BE64_MAX ? tag_create_deterministic(hash) : TAG_ALL); for (i = 0; i < cls->n_tries; i++) { subtable->trie_plen[i] = minimask_get_prefix_len(mask, cls->tries[i].field); } /* Ports trie. */ ovsrcu_set_hidden(&subtable->ports_trie, NULL); *CONST_CAST(int *, &subtable->ports_mask_len) = 32 - ctz32(ntohl(MINIFLOW_GET_BE32(&mask->masks, tp_src))); /* List of rules. */ rculist_init(&subtable->rules_list); cmap_insert(&cls->subtables_map, &subtable->cmap_node, hash); return subtable; } /* RCU readers may still access the subtable before it is actually freed. */ static void destroy_subtable(struct classifier *cls, struct cls_subtable *subtable) { int i; pvector_remove(&cls->subtables, subtable); cmap_remove(&cls->subtables_map, &subtable->cmap_node, minimask_hash(&subtable->mask, 0)); ovs_assert(ovsrcu_get_protected(struct trie_node *, &subtable->ports_trie) == NULL); ovs_assert(cmap_is_empty(&subtable->rules)); ovs_assert(rculist_is_empty(&subtable->rules_list)); for (i = 0; i < subtable->n_indices; i++) { cmap_destroy(&subtable->indices[i]); } cmap_destroy(&subtable->rules); ovsrcu_postpone(free, subtable); } struct range { uint8_t start; uint8_t end; }; static unsigned int be_get_bit_at(const ovs_be32 value[], unsigned int ofs); /* Return 'true' if can skip rest of the subtable based on the prefix trie * lookup results. */ static inline bool check_tries(struct trie_ctx trie_ctx[CLS_MAX_TRIES], unsigned int n_tries, const unsigned int field_plen[CLS_MAX_TRIES], const struct range ofs, const struct flow *flow, struct flow_wildcards *wc) { int j; /* Check if we could avoid fully unwildcarding the next level of * fields using the prefix tries. The trie checks are done only as * needed to avoid folding in additional bits to the wildcards mask. */ for (j = 0; j < n_tries; j++) { /* Is the trie field relevant for this subtable? */ if (field_plen[j]) { struct trie_ctx *ctx = &trie_ctx[j]; uint8_t be32ofs = ctx->be32ofs; uint8_t be64ofs = be32ofs / 2; /* Is the trie field within the current range of fields? */ if (be64ofs >= ofs.start && be64ofs < ofs.end) { /* On-demand trie lookup. */ if (!ctx->lookup_done) { memset(&ctx->match_plens, 0, sizeof ctx->match_plens); ctx->maskbits = trie_lookup(ctx->trie, flow, &ctx->match_plens); ctx->lookup_done = true; } /* Possible to skip the rest of the subtable if subtable's * prefix on the field is not included in the lookup result. */ if (!be_get_bit_at(&ctx->match_plens.be32, field_plen[j] - 1)) { /* We want the trie lookup to never result in unwildcarding * any bits that would not be unwildcarded otherwise. * Since the trie is shared by the whole classifier, it is * possible that the 'maskbits' contain bits that are * irrelevant for the partition relevant for the current * packet. Hence the checks below. */ /* Check that the trie result will not unwildcard more bits * than this subtable would otherwise. */ if (ctx->maskbits <= field_plen[j]) { /* Unwildcard the bits and skip the rest. */ mask_set_prefix_bits(wc, be32ofs, ctx->maskbits); /* Note: Prerequisite already unwildcarded, as the only * prerequisite of the supported trie lookup fields is * the ethertype, which is always unwildcarded. */ return true; } /* Can skip if the field is already unwildcarded. */ if (mask_prefix_bits_set(wc, be32ofs, ctx->maskbits)) { return true; } } } } } return false; } /* Returns true if 'target' satisifies 'flow'/'mask', that is, if each bit * for which 'flow', for which 'mask' has a bit set, specifies a particular * value has the correct value in 'target'. * * This function is equivalent to miniflow_equal_flow_in_minimask(flow, * target, mask) but this is faster because of the invariant that * flow->map and mask->masks.map are the same, and that this version * takes the 'wc'. */ static inline bool miniflow_and_mask_matches_flow(const struct miniflow *flow, const struct minimask *mask, const struct flow *target) { const uint64_t *flowp = miniflow_get_values(flow); const uint64_t *maskp = miniflow_get_values(&mask->masks); int idx; MAP_FOR_EACH_INDEX(idx, mask->masks.map) { uint64_t diff = (*flowp++ ^ flow_u64_value(target, idx)) & *maskp++; if (diff) { return false; } } return true; } static inline const struct cls_match * find_match(const struct cls_subtable *subtable, const struct flow *flow, uint32_t hash) { const struct cls_match *rule; CMAP_FOR_EACH_WITH_HASH (rule, cmap_node, hash, &subtable->rules) { if (miniflow_and_mask_matches_flow(&rule->flow, &subtable->mask, flow)) { return rule; } } return NULL; } /* Returns true if 'target' satisifies 'flow'/'mask', that is, if each bit * for which 'flow', for which 'mask' has a bit set, specifies a particular * value has the correct value in 'target'. * * This function is equivalent to miniflow_and_mask_matches_flow() but this * version fills in the mask bits in 'wc'. */ static inline bool miniflow_and_mask_matches_flow_wc(const struct miniflow *flow, const struct minimask *mask, const struct flow *target, struct flow_wildcards *wc) { const uint64_t *flowp = miniflow_get_values(flow); const uint64_t *maskp = miniflow_get_values(&mask->masks); int idx; MAP_FOR_EACH_INDEX(idx, mask->masks.map) { uint64_t mask = *maskp++; uint64_t diff = (*flowp++ ^ flow_u64_value(target, idx)) & mask; if (diff) { /* Only unwildcard if none of the differing bits is already * exact-matched. */ if (!(flow_u64_value(&wc->masks, idx) & diff)) { /* Keep one bit of the difference. The selected bit may be * different in big-endian v.s. little-endian systems. */ *flow_u64_lvalue(&wc->masks, idx) |= rightmost_1bit(diff); } return false; } /* Fill in the bits that were looked at. */ *flow_u64_lvalue(&wc->masks, idx) |= mask; } return true; } /* Unwildcard the fields looked up so far, if any. */ static void fill_range_wc(const struct cls_subtable *subtable, struct flow_wildcards *wc, uint8_t to) { if (to) { flow_wildcards_fold_minimask_range(wc, &subtable->mask, 0, to); } } static const struct cls_match * find_match_wc(const struct cls_subtable *subtable, const struct flow *flow, struct trie_ctx trie_ctx[CLS_MAX_TRIES], unsigned int n_tries, struct flow_wildcards *wc) { uint32_t basis = 0, hash; const struct cls_match *rule = NULL; int i; struct range ofs; if (OVS_UNLIKELY(!wc)) { return find_match(subtable, flow, flow_hash_in_minimask(flow, &subtable->mask, 0)); } ofs.start = 0; /* Try to finish early by checking fields in segments. */ for (i = 0; i < subtable->n_indices; i++) { const struct cmap_node *inode; ofs.end = subtable->index_ofs[i]; if (check_tries(trie_ctx, n_tries, subtable->trie_plen, ofs, flow, wc)) { /* 'wc' bits for the trie field set, now unwildcard the preceding * bits used so far. */ fill_range_wc(subtable, wc, ofs.start); return NULL; } hash = flow_hash_in_minimask_range(flow, &subtable->mask, ofs.start, ofs.end, &basis); inode = cmap_find(&subtable->indices[i], hash); if (!inode) { /* No match, can stop immediately, but must fold in the bits * used in lookup so far. */ fill_range_wc(subtable, wc, ofs.end); return NULL; } /* If we have narrowed down to a single rule already, check whether * that rule matches. Either way, we're done. * * (Rare) hash collisions may cause us to miss the opportunity for this * optimization. */ if (!cmap_node_next(inode)) { ASSIGN_CONTAINER(rule, inode - i, index_nodes); if (miniflow_and_mask_matches_flow_wc(&rule->flow, &subtable->mask, flow, wc)) { return rule; } return NULL; } ofs.start = ofs.end; } ofs.end = FLOW_U64S; /* Trie check for the final range. */ if (check_tries(trie_ctx, n_tries, subtable->trie_plen, ofs, flow, wc)) { fill_range_wc(subtable, wc, ofs.start); return NULL; } hash = flow_hash_in_minimask_range(flow, &subtable->mask, ofs.start, ofs.end, &basis); rule = find_match(subtable, flow, hash); if (!rule && subtable->ports_mask_len) { /* Ports are always part of the final range, if any. * No match was found for the ports. Use the ports trie to figure out * which ports bits to unwildcard. */ unsigned int mbits; ovs_be32 value, plens, mask; mask = MINIFLOW_GET_BE32(&subtable->mask.masks, tp_src); value = ((OVS_FORCE ovs_be32 *)flow)[TP_PORTS_OFS32] & mask; mbits = trie_lookup_value(&subtable->ports_trie, &value, &plens, 32); ((OVS_FORCE ovs_be32 *)&wc->masks)[TP_PORTS_OFS32] |= mask & be32_prefix_mask(mbits); /* Unwildcard all bits in the mask upto the ports, as they were used * to determine there is no match. */ fill_range_wc(subtable, wc, TP_PORTS_OFS64); return NULL; } /* Must unwildcard all the fields, as they were looked at. */ flow_wildcards_fold_minimask(wc, &subtable->mask); return rule; } static struct cls_match * find_equal(const struct cls_subtable *subtable, const struct miniflow *flow, uint32_t hash) { struct cls_match *head; CMAP_FOR_EACH_WITH_HASH (head, cmap_node, hash, &subtable->rules) { if (miniflow_equal(&head->flow, flow)) { return head; } } return NULL; } /* A longest-prefix match tree. */ /* Return at least 'plen' bits of the 'prefix', starting at bit offset 'ofs'. * Prefixes are in the network byte order, and the offset 0 corresponds to * the most significant bit of the first byte. The offset can be read as * "how many bits to skip from the start of the prefix starting at 'pr'". */ static uint32_t raw_get_prefix(const ovs_be32 pr[], unsigned int ofs, unsigned int plen) { uint32_t prefix; pr += ofs / 32; /* Where to start. */ ofs %= 32; /* How many bits to skip at 'pr'. */ prefix = ntohl(*pr) << ofs; /* Get the first 32 - ofs bits. */ if (plen > 32 - ofs) { /* Need more than we have already? */ prefix |= ntohl(*++pr) >> (32 - ofs); } /* Return with possible unwanted bits at the end. */ return prefix; } /* Return min(TRIE_PREFIX_BITS, plen) bits of the 'prefix', starting at bit * offset 'ofs'. Prefixes are in the network byte order, and the offset 0 * corresponds to the most significant bit of the first byte. The offset can * be read as "how many bits to skip from the start of the prefix starting at * 'pr'". */ static uint32_t trie_get_prefix(const ovs_be32 pr[], unsigned int ofs, unsigned int plen) { if (!plen) { return 0; } if (plen > TRIE_PREFIX_BITS) { plen = TRIE_PREFIX_BITS; /* Get at most TRIE_PREFIX_BITS. */ } /* Return with unwanted bits cleared. */ return raw_get_prefix(pr, ofs, plen) & ~0u << (32 - plen); } /* Return the number of equal bits in 'n_bits' of 'prefix's MSBs and a 'value' * starting at "MSB 0"-based offset 'ofs'. */ static unsigned int prefix_equal_bits(uint32_t prefix, unsigned int n_bits, const ovs_be32 value[], unsigned int ofs) { uint64_t diff = prefix ^ raw_get_prefix(value, ofs, n_bits); /* Set the bit after the relevant bits to limit the result. */ return raw_clz64(diff << 32 | UINT64_C(1) << (63 - n_bits)); } /* Return the number of equal bits in 'node' prefix and a 'prefix' of length * 'plen', starting at "MSB 0"-based offset 'ofs'. */ static unsigned int trie_prefix_equal_bits(const struct trie_node *node, const ovs_be32 prefix[], unsigned int ofs, unsigned int plen) { return prefix_equal_bits(node->prefix, MIN(node->n_bits, plen - ofs), prefix, ofs); } /* Return the bit at ("MSB 0"-based) offset 'ofs' as an int. 'ofs' can * be greater than 31. */ static unsigned int be_get_bit_at(const ovs_be32 value[], unsigned int ofs) { return (((const uint8_t *)value)[ofs / 8] >> (7 - ofs % 8)) & 1u; } /* Return the bit at ("MSB 0"-based) offset 'ofs' as an int. 'ofs' must * be between 0 and 31, inclusive. */ static unsigned int get_bit_at(const uint32_t prefix, unsigned int ofs) { return (prefix >> (31 - ofs)) & 1u; } /* Create new branch. */ static struct trie_node * trie_branch_create(const ovs_be32 *prefix, unsigned int ofs, unsigned int plen, unsigned int n_rules) { struct trie_node *node = xmalloc(sizeof *node); node->prefix = trie_get_prefix(prefix, ofs, plen); if (plen <= TRIE_PREFIX_BITS) { node->n_bits = plen; ovsrcu_set_hidden(&node->edges[0], NULL); ovsrcu_set_hidden(&node->edges[1], NULL); node->n_rules = n_rules; } else { /* Need intermediate nodes. */ struct trie_node *subnode = trie_branch_create(prefix, ofs + TRIE_PREFIX_BITS, plen - TRIE_PREFIX_BITS, n_rules); int bit = get_bit_at(subnode->prefix, 0); node->n_bits = TRIE_PREFIX_BITS; ovsrcu_set_hidden(&node->edges[bit], subnode); ovsrcu_set_hidden(&node->edges[!bit], NULL); node->n_rules = 0; } return node; } static void trie_node_destroy(const struct trie_node *node) { ovsrcu_postpone(free, CONST_CAST(struct trie_node *, node)); } /* Copy a trie node for modification and postpone delete the old one. */ static struct trie_node * trie_node_rcu_realloc(const struct trie_node *node) { struct trie_node *new_node = xmalloc(sizeof *node); *new_node = *node; trie_node_destroy(node); return new_node; } static void trie_destroy(rcu_trie_ptr *trie) { struct trie_node *node = ovsrcu_get_protected(struct trie_node *, trie); if (node) { ovsrcu_set_hidden(trie, NULL); trie_destroy(&node->edges[0]); trie_destroy(&node->edges[1]); trie_node_destroy(node); } } static bool trie_is_leaf(const struct trie_node *trie) { /* No children? */ return !ovsrcu_get(struct trie_node *, &trie->edges[0]) && !ovsrcu_get(struct trie_node *, &trie->edges[1]); } static void mask_set_prefix_bits(struct flow_wildcards *wc, uint8_t be32ofs, unsigned int n_bits) { ovs_be32 *mask = &((ovs_be32 *)&wc->masks)[be32ofs]; unsigned int i; for (i = 0; i < n_bits / 32; i++) { mask[i] = OVS_BE32_MAX; } if (n_bits % 32) { mask[i] |= htonl(~0u << (32 - n_bits % 32)); } } static bool mask_prefix_bits_set(const struct flow_wildcards *wc, uint8_t be32ofs, unsigned int n_bits) { ovs_be32 *mask = &((ovs_be32 *)&wc->masks)[be32ofs]; unsigned int i; ovs_be32 zeroes = 0; for (i = 0; i < n_bits / 32; i++) { zeroes |= ~mask[i]; } if (n_bits % 32) { zeroes |= ~mask[i] & htonl(~0u << (32 - n_bits % 32)); } return !zeroes; /* All 'n_bits' bits set. */ } static rcu_trie_ptr * trie_next_edge(struct trie_node *node, const ovs_be32 value[], unsigned int ofs) { return node->edges + be_get_bit_at(value, ofs); } static const struct trie_node * trie_next_node(const struct trie_node *node, const ovs_be32 value[], unsigned int ofs) { return ovsrcu_get(struct trie_node *, &node->edges[be_get_bit_at(value, ofs)]); } /* Set the bit at ("MSB 0"-based) offset 'ofs'. 'ofs' can be greater than 31. */ static void be_set_bit_at(ovs_be32 value[], unsigned int ofs) { ((uint8_t *)value)[ofs / 8] |= 1u << (7 - ofs % 8); } /* Returns the number of bits in the prefix mask necessary to determine a * mismatch, in case there are longer prefixes in the tree below the one that * matched. * '*plens' will have a bit set for each prefix length that may have matching * rules. The caller is responsible for clearing the '*plens' prior to * calling this. */ static unsigned int trie_lookup_value(const rcu_trie_ptr *trie, const ovs_be32 value[], ovs_be32 plens[], unsigned int n_bits) { const struct trie_node *prev = NULL; const struct trie_node *node = ovsrcu_get(struct trie_node *, trie); unsigned int match_len = 0; /* Number of matching bits. */ for (; node; prev = node, node = trie_next_node(node, value, match_len)) { unsigned int eqbits; /* Check if this edge can be followed. */ eqbits = prefix_equal_bits(node->prefix, node->n_bits, value, match_len); match_len += eqbits; if (eqbits < node->n_bits) { /* Mismatch, nothing more to be found. */ /* Bit at offset 'match_len' differed. */ return match_len + 1; /* Includes the first mismatching bit. */ } /* Full match, check if rules exist at this prefix length. */ if (node->n_rules > 0) { be_set_bit_at(plens, match_len - 1); } if (match_len >= n_bits) { return n_bits; /* Full prefix. */ } } /* node == NULL. Full match so far, but we tried to follow an * non-existing branch. Need to exclude the other branch if it exists * (it does not if we were called on an empty trie or 'prev' is a leaf * node). */ return !prev || trie_is_leaf(prev) ? match_len : match_len + 1; } static unsigned int trie_lookup(const struct cls_trie *trie, const struct flow *flow, union mf_value *plens) { const struct mf_field *mf = trie->field; /* Check that current flow matches the prerequisites for the trie * field. Some match fields are used for multiple purposes, so we * must check that the trie is relevant for this flow. */ if (mf_are_prereqs_ok(mf, flow)) { return trie_lookup_value(&trie->root, &((ovs_be32 *)flow)[mf->flow_be32ofs], &plens->be32, mf->n_bits); } memset(plens, 0xff, sizeof *plens); /* All prefixes, no skipping. */ return 0; /* Value not used in this case. */ } /* Returns the length of a prefix match mask for the field 'mf' in 'minimask'. * Returns the u32 offset to the miniflow data in '*miniflow_index', if * 'miniflow_index' is not NULL. */ static unsigned int minimask_get_prefix_len(const struct minimask *minimask, const struct mf_field *mf) { unsigned int n_bits = 0, mask_tz = 0; /* Non-zero when end of mask seen. */ uint8_t be32_ofs = mf->flow_be32ofs; uint8_t be32_end = be32_ofs + mf->n_bytes / 4; for (; be32_ofs < be32_end; ++be32_ofs) { uint32_t mask = ntohl(minimask_get_be32(minimask, be32_ofs)); /* Validate mask, count the mask length. */ if (mask_tz) { if (mask) { return 0; /* No bits allowed after mask ended. */ } } else { if (~mask & (~mask + 1)) { return 0; /* Mask not contiguous. */ } mask_tz = ctz32(mask); n_bits += 32 - mask_tz; } } return n_bits; } /* * This is called only when mask prefix is known to be CIDR and non-zero. * Relies on the fact that the flow and mask have the same map, and since * the mask is CIDR, the storage for the flow field exists even if it * happened to be zeros. */ static const ovs_be32 * minimatch_get_prefix(const struct minimatch *match, const struct mf_field *mf) { return (OVS_FORCE const ovs_be32 *) (miniflow_get_values(&match->flow) + count_1bits(match->flow.map & ((UINT64_C(1) << mf->flow_be32ofs / 2) - 1))) + (mf->flow_be32ofs & 1); } /* Insert rule in to the prefix tree. * 'mlen' must be the (non-zero) CIDR prefix length of the 'trie->field' mask * in 'rule'. */ static void trie_insert(struct cls_trie *trie, const struct cls_rule *rule, int mlen) { trie_insert_prefix(&trie->root, minimatch_get_prefix(&rule->match, trie->field), mlen); } static void trie_insert_prefix(rcu_trie_ptr *edge, const ovs_be32 *prefix, int mlen) { struct trie_node *node; int ofs = 0; /* Walk the tree. */ for (; (node = ovsrcu_get_protected(struct trie_node *, edge)); edge = trie_next_edge(node, prefix, ofs)) { unsigned int eqbits = trie_prefix_equal_bits(node, prefix, ofs, mlen); ofs += eqbits; if (eqbits < node->n_bits) { /* Mismatch, new node needs to be inserted above. */ int old_branch = get_bit_at(node->prefix, eqbits); struct trie_node *new_parent; new_parent = trie_branch_create(prefix, ofs - eqbits, eqbits, ofs == mlen ? 1 : 0); /* Copy the node to modify it. */ node = trie_node_rcu_realloc(node); /* Adjust the new node for its new position in the tree. */ node->prefix <<= eqbits; node->n_bits -= eqbits; ovsrcu_set_hidden(&new_parent->edges[old_branch], node); /* Check if need a new branch for the new rule. */ if (ofs < mlen) { ovsrcu_set_hidden(&new_parent->edges[!old_branch], trie_branch_create(prefix, ofs, mlen - ofs, 1)); } ovsrcu_set(edge, new_parent); /* Publish changes. */ return; } /* Full match so far. */ if (ofs == mlen) { /* Full match at the current node, rule needs to be added here. */ node->n_rules++; return; } } /* Must insert a new tree branch for the new rule. */ ovsrcu_set(edge, trie_branch_create(prefix, ofs, mlen - ofs, 1)); } /* 'mlen' must be the (non-zero) CIDR prefix length of the 'trie->field' mask * in 'rule'. */ static void trie_remove(struct cls_trie *trie, const struct cls_rule *rule, int mlen) { trie_remove_prefix(&trie->root, minimatch_get_prefix(&rule->match, trie->field), mlen); } /* 'mlen' must be the (non-zero) CIDR prefix length of the 'trie->field' mask * in 'rule'. */ static void trie_remove_prefix(rcu_trie_ptr *root, const ovs_be32 *prefix, int mlen) { struct trie_node *node; rcu_trie_ptr *edges[sizeof(union mf_value) * 8]; int depth = 0, ofs = 0; /* Walk the tree. */ for (edges[0] = root; (node = ovsrcu_get_protected(struct trie_node *, edges[depth])); edges[++depth] = trie_next_edge(node, prefix, ofs)) { unsigned int eqbits = trie_prefix_equal_bits(node, prefix, ofs, mlen); if (eqbits < node->n_bits) { /* Mismatch, nothing to be removed. This should never happen, as * only rules in the classifier are ever removed. */ break; /* Log a warning. */ } /* Full match so far. */ ofs += eqbits; if (ofs == mlen) { /* Full prefix match at the current node, remove rule here. */ if (!node->n_rules) { break; /* Log a warning. */ } node->n_rules--; /* Check if can prune the tree. */ while (!node->n_rules) { struct trie_node *next, *edge0 = ovsrcu_get_protected(struct trie_node *, &node->edges[0]), *edge1 = ovsrcu_get_protected(struct trie_node *, &node->edges[1]); if (edge0 && edge1) { break; /* A branching point, cannot prune. */ } /* Else have at most one child node, remove this node. */ next = edge0 ? edge0 : edge1; if (next) { if (node->n_bits + next->n_bits > TRIE_PREFIX_BITS) { break; /* Cannot combine. */ } next = trie_node_rcu_realloc(next); /* Modify. */ /* Combine node with next. */ next->prefix = node->prefix | next->prefix >> node->n_bits; next->n_bits += node->n_bits; } /* Update the parent's edge. */ ovsrcu_set(edges[depth], next); /* Publish changes. */ trie_node_destroy(node); if (next || !depth) { /* Branch not pruned or at root, nothing more to do. */ break; } node = ovsrcu_get_protected(struct trie_node *, edges[--depth]); } return; } } /* Cannot go deeper. This should never happen, since only rules * that actually exist in the classifier are ever removed. */ VLOG_WARN("Trying to remove non-existing rule from a prefix trie."); }