| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Daniel Mack | 1505 | 59.00% | 1 | 5.88% |
| Craig Gallek | 427 | 16.74% | 2 | 11.76% |
| Yonghong Song | 417 | 16.35% | 5 | 29.41% |
| Daniel Borkmann | 143 | 5.61% | 3 | 17.65% |
| Martin KaFai Lau | 26 | 1.02% | 1 | 5.88% |
| Alexei Starovoitov | 25 | 0.98% | 1 | 5.88% |
| Jakub Kiciński | 4 | 0.16% | 1 | 5.88% |
| Kees Cook | 2 | 0.08% | 1 | 5.88% |
| Johannes Berg | 1 | 0.04% | 1 | 5.88% |
| Chenbo Feng | 1 | 0.04% | 1 | 5.88% |
| Total | 2551 | 17 |
/* * Longest prefix match list implementation * * Copyright (c) 2016,2017 Daniel Mack * Copyright (c) 2016 David Herrmann * * This file is subject to the terms and conditions of version 2 of the GNU * General Public License. See the file COPYING in the main directory of the * Linux distribution for more details. */ #include <linux/bpf.h> #include <linux/btf.h> #include <linux/err.h> #include <linux/slab.h> #include <linux/spinlock.h> #include <linux/vmalloc.h> #include <net/ipv6.h> #include <uapi/linux/btf.h> /* Intermediate node */ #define LPM_TREE_NODE_FLAG_IM BIT(0) struct lpm_trie_node; struct lpm_trie_node { struct rcu_head rcu; struct lpm_trie_node __rcu *child[2]; u32 prefixlen; u32 flags; u8 data[0]; }; struct lpm_trie { struct bpf_map map; struct lpm_trie_node __rcu *root; size_t n_entries; size_t max_prefixlen; size_t data_size; raw_spinlock_t lock; }; /* This trie implements a longest prefix match algorithm that can be used to * match IP addresses to a stored set of ranges. * * Data stored in @data of struct bpf_lpm_key and struct lpm_trie_node is * interpreted as big endian, so data[0] stores the most significant byte. * * Match ranges are internally stored in instances of struct lpm_trie_node * which each contain their prefix length as well as two pointers that may * lead to more nodes containing more specific matches. Each node also stores * a value that is defined by and returned to userspace via the update_elem * and lookup functions. * * For instance, let's start with a trie that was created with a prefix length * of 32, so it can be used for IPv4 addresses, and one single element that * matches 192.168.0.0/16. The data array would hence contain * [0xc0, 0xa8, 0x00, 0x00] in big-endian notation. This documentation will * stick to IP-address notation for readability though. * * As the trie is empty initially, the new node (1) will be places as root * node, denoted as (R) in the example below. As there are no other node, both * child pointers are %NULL. * * +----------------+ * | (1) (R) | * | 192.168.0.0/16 | * | value: 1 | * | [0] [1] | * +----------------+ * * Next, let's add a new node (2) matching 192.168.0.0/24. As there is already * a node with the same data and a smaller prefix (ie, a less specific one), * node (2) will become a child of (1). In child index depends on the next bit * that is outside of what (1) matches, and that bit is 0, so (2) will be * child[0] of (1): * * +----------------+ * | (1) (R) | * | 192.168.0.0/16 | * | value: 1 | * | [0] [1] | * +----------------+ * | * +----------------+ * | (2) | * | 192.168.0.0/24 | * | value: 2 | * | [0] [1] | * +----------------+ * * The child[1] slot of (1) could be filled with another node which has bit #17 * (the next bit after the ones that (1) matches on) set to 1. For instance, * 192.168.128.0/24: * * +----------------+ * | (1) (R) | * | 192.168.0.0/16 | * | value: 1 | * | [0] [1] | * +----------------+ * | | * +----------------+ +------------------+ * | (2) | | (3) | * | 192.168.0.0/24 | | 192.168.128.0/24 | * | value: 2 | | value: 3 | * | [0] [1] | | [0] [1] | * +----------------+ +------------------+ * * Let's add another node (4) to the game for 192.168.1.0/24. In order to place * it, node (1) is looked at first, and because (4) of the semantics laid out * above (bit #17 is 0), it would normally be attached to (1) as child[0]. * However, that slot is already allocated, so a new node is needed in between. * That node does not have a value attached to it and it will never be * returned to users as result of a lookup. It is only there to differentiate * the traversal further. It will get a prefix as wide as necessary to * distinguish its two children: * * +----------------+ * | (1) (R) | * | 192.168.0.0/16 | * | value: 1 | * | [0] [1] | * +----------------+ * | | * +----------------+ +------------------+ * | (4) (I) | | (3) | * | 192.168.0.0/23 | | 192.168.128.0/24 | * | value: --- | | value: 3 | * | [0] [1] | | [0] [1] | * +----------------+ +------------------+ * | | * +----------------+ +----------------+ * | (2) | | (5) | * | 192.168.0.0/24 | | 192.168.1.0/24 | * | value: 2 | | value: 5 | * | [0] [1] | | [0] [1] | * +----------------+ +----------------+ * * 192.168.1.1/32 would be a child of (5) etc. * * An intermediate node will be turned into a 'real' node on demand. In the * example above, (4) would be re-used if 192.168.0.0/23 is added to the trie. * * A fully populated trie would have a height of 32 nodes, as the trie was * created with a prefix length of 32. * * The lookup starts at the root node. If the current node matches and if there * is a child that can be used to become more specific, the trie is traversed * downwards. The last node in the traversal that is a non-intermediate one is * returned. */ static inline int extract_bit(const u8 *data, size_t index) { return !!(data[index / 8] & (1 << (7 - (index % 8)))); } /** * longest_prefix_match() - determine the longest prefix * @trie: The trie to get internal sizes from * @node: The node to operate on * @key: The key to compare to @node * * Determine the longest prefix of @node that matches the bits in @key. */ static size_t longest_prefix_match(const struct lpm_trie *trie, const struct lpm_trie_node *node, const struct bpf_lpm_trie_key *key) { size_t prefixlen = 0; size_t i; for (i = 0; i < trie->data_size; i++) { size_t b; b = 8 - fls(node->data[i] ^ key->data[i]); prefixlen += b; if (prefixlen >= node->prefixlen || prefixlen >= key->prefixlen) return min(node->prefixlen, key->prefixlen); if (b < 8) break; } return prefixlen; } /* Called from syscall or from eBPF program */ static void *trie_lookup_elem(struct bpf_map *map, void *_key) { struct lpm_trie *trie = container_of(map, struct lpm_trie, map); struct lpm_trie_node *node, *found = NULL; struct bpf_lpm_trie_key *key = _key; /* Start walking the trie from the root node ... */ for (node = rcu_dereference(trie->root); node;) { unsigned int next_bit; size_t matchlen; /* Determine the longest prefix of @node that matches @key. * If it's the maximum possible prefix for this trie, we have * an exact match and can return it directly. */ matchlen = longest_prefix_match(trie, node, key); if (matchlen == trie->max_prefixlen) { found = node; break; } /* If the number of bits that match is smaller than the prefix * length of @node, bail out and return the node we have seen * last in the traversal (ie, the parent). */ if (matchlen < node->prefixlen) break; /* Consider this node as return candidate unless it is an * artificially added intermediate one. */ if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) found = node; /* If the node match is fully satisfied, let's see if we can * become more specific. Determine the next bit in the key and * traverse down. */ next_bit = extract_bit(key->data, node->prefixlen); node = rcu_dereference(node->child[next_bit]); } if (!found) return NULL; return found->data + trie->data_size; } static struct lpm_trie_node *lpm_trie_node_alloc(const struct lpm_trie *trie, const void *value) { struct lpm_trie_node *node; size_t size = sizeof(struct lpm_trie_node) + trie->data_size; if (value) size += trie->map.value_size; node = kmalloc_node(size, GFP_ATOMIC | __GFP_NOWARN, trie->map.numa_node); if (!node) return NULL; node->flags = 0; if (value) memcpy(node->data + trie->data_size, value, trie->map.value_size); return node; } /* Called from syscall or from eBPF program */ static int trie_update_elem(struct bpf_map *map, void *_key, void *value, u64 flags) { struct lpm_trie *trie = container_of(map, struct lpm_trie, map); struct lpm_trie_node *node, *im_node = NULL, *new_node = NULL; struct lpm_trie_node __rcu **slot; struct bpf_lpm_trie_key *key = _key; unsigned long irq_flags; unsigned int next_bit; size_t matchlen = 0; int ret = 0; if (unlikely(flags > BPF_EXIST)) return -EINVAL; if (key->prefixlen > trie->max_prefixlen) return -EINVAL; raw_spin_lock_irqsave(&trie->lock, irq_flags); /* Allocate and fill a new node */ if (trie->n_entries == trie->map.max_entries) { ret = -ENOSPC; goto out; } new_node = lpm_trie_node_alloc(trie, value); if (!new_node) { ret = -ENOMEM; goto out; } trie->n_entries++; new_node->prefixlen = key->prefixlen; RCU_INIT_POINTER(new_node->child[0], NULL); RCU_INIT_POINTER(new_node->child[1], NULL); memcpy(new_node->data, key->data, trie->data_size); /* Now find a slot to attach the new node. To do that, walk the tree * from the root and match as many bits as possible for each node until * we either find an empty slot or a slot that needs to be replaced by * an intermediate node. */ slot = &trie->root; while ((node = rcu_dereference_protected(*slot, lockdep_is_held(&trie->lock)))) { matchlen = longest_prefix_match(trie, node, key); if (node->prefixlen != matchlen || node->prefixlen == key->prefixlen || node->prefixlen == trie->max_prefixlen) break; next_bit = extract_bit(key->data, node->prefixlen); slot = &node->child[next_bit]; } /* If the slot is empty (a free child pointer or an empty root), * simply assign the @new_node to that slot and be done. */ if (!node) { rcu_assign_pointer(*slot, new_node); goto out; } /* If the slot we picked already exists, replace it with @new_node * which already has the correct data array set. */ if (node->prefixlen == matchlen) { new_node->child[0] = node->child[0]; new_node->child[1] = node->child[1]; if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) trie->n_entries--; rcu_assign_pointer(*slot, new_node); kfree_rcu(node, rcu); goto out; } /* If the new node matches the prefix completely, it must be inserted * as an ancestor. Simply insert it between @node and *@slot. */ if (matchlen == key->prefixlen) { next_bit = extract_bit(node->data, matchlen); rcu_assign_pointer(new_node->child[next_bit], node); rcu_assign_pointer(*slot, new_node); goto out; } im_node = lpm_trie_node_alloc(trie, NULL); if (!im_node) { ret = -ENOMEM; goto out; } im_node->prefixlen = matchlen; im_node->flags |= LPM_TREE_NODE_FLAG_IM; memcpy(im_node->data, node->data, trie->data_size); /* Now determine which child to install in which slot */ if (extract_bit(key->data, matchlen)) { rcu_assign_pointer(im_node->child[0], node); rcu_assign_pointer(im_node->child[1], new_node); } else { rcu_assign_pointer(im_node->child[0], new_node); rcu_assign_pointer(im_node->child[1], node); } /* Finally, assign the intermediate node to the determined spot */ rcu_assign_pointer(*slot, im_node); out: if (ret) { if (new_node) trie->n_entries--; kfree(new_node); kfree(im_node); } raw_spin_unlock_irqrestore(&trie->lock, irq_flags); return ret; } /* Called from syscall or from eBPF program */ static int trie_delete_elem(struct bpf_map *map, void *_key) { struct lpm_trie *trie = container_of(map, struct lpm_trie, map); struct bpf_lpm_trie_key *key = _key; struct lpm_trie_node __rcu **trim, **trim2; struct lpm_trie_node *node, *parent; unsigned long irq_flags; unsigned int next_bit; size_t matchlen = 0; int ret = 0; if (key->prefixlen > trie->max_prefixlen) return -EINVAL; raw_spin_lock_irqsave(&trie->lock, irq_flags); /* Walk the tree looking for an exact key/length match and keeping * track of the path we traverse. We will need to know the node * we wish to delete, and the slot that points to the node we want * to delete. We may also need to know the nodes parent and the * slot that contains it. */ trim = &trie->root; trim2 = trim; parent = NULL; while ((node = rcu_dereference_protected( *trim, lockdep_is_held(&trie->lock)))) { matchlen = longest_prefix_match(trie, node, key); if (node->prefixlen != matchlen || node->prefixlen == key->prefixlen) break; parent = node; trim2 = trim; next_bit = extract_bit(key->data, node->prefixlen); trim = &node->child[next_bit]; } if (!node || node->prefixlen != key->prefixlen || (node->flags & LPM_TREE_NODE_FLAG_IM)) { ret = -ENOENT; goto out; } trie->n_entries--; /* If the node we are removing has two children, simply mark it * as intermediate and we are done. */ if (rcu_access_pointer(node->child[0]) && rcu_access_pointer(node->child[1])) { node->flags |= LPM_TREE_NODE_FLAG_IM; goto out; } /* If the parent of the node we are about to delete is an intermediate * node, and the deleted node doesn't have any children, we can delete * the intermediate parent as well and promote its other child * up the tree. Doing this maintains the invariant that all * intermediate nodes have exactly 2 children and that there are no * unnecessary intermediate nodes in the tree. */ if (parent && (parent->flags & LPM_TREE_NODE_FLAG_IM) && !node->child[0] && !node->child[1]) { if (node == rcu_access_pointer(parent->child[0])) rcu_assign_pointer( *trim2, rcu_access_pointer(parent->child[1])); else rcu_assign_pointer( *trim2, rcu_access_pointer(parent->child[0])); kfree_rcu(parent, rcu); kfree_rcu(node, rcu); goto out; } /* The node we are removing has either zero or one child. If there * is a child, move it into the removed node's slot then delete * the node. Otherwise just clear the slot and delete the node. */ if (node->child[0]) rcu_assign_pointer(*trim, rcu_access_pointer(node->child[0])); else if (node->child[1]) rcu_assign_pointer(*trim, rcu_access_pointer(node->child[1])); else RCU_INIT_POINTER(*trim, NULL); kfree_rcu(node, rcu); out: raw_spin_unlock_irqrestore(&trie->lock, irq_flags); return ret; } #define LPM_DATA_SIZE_MAX 256 #define LPM_DATA_SIZE_MIN 1 #define LPM_VAL_SIZE_MAX (KMALLOC_MAX_SIZE - LPM_DATA_SIZE_MAX - \ sizeof(struct lpm_trie_node)) #define LPM_VAL_SIZE_MIN 1 #define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key) + (X)) #define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX) #define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN) #define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \ BPF_F_RDONLY | BPF_F_WRONLY) static struct bpf_map *trie_alloc(union bpf_attr *attr) { struct lpm_trie *trie; u64 cost = sizeof(*trie), cost_per_node; int ret; if (!capable(CAP_SYS_ADMIN)) return ERR_PTR(-EPERM); /* check sanity of attributes */ if (attr->max_entries == 0 || !(attr->map_flags & BPF_F_NO_PREALLOC) || attr->map_flags & ~LPM_CREATE_FLAG_MASK || attr->key_size < LPM_KEY_SIZE_MIN || attr->key_size > LPM_KEY_SIZE_MAX || attr->value_size < LPM_VAL_SIZE_MIN || attr->value_size > LPM_VAL_SIZE_MAX) return ERR_PTR(-EINVAL); trie = kzalloc(sizeof(*trie), GFP_USER | __GFP_NOWARN); if (!trie) return ERR_PTR(-ENOMEM); /* copy mandatory map attributes */ bpf_map_init_from_attr(&trie->map, attr); trie->data_size = attr->key_size - offsetof(struct bpf_lpm_trie_key, data); trie->max_prefixlen = trie->data_size * 8; cost_per_node = sizeof(struct lpm_trie_node) + attr->value_size + trie->data_size; cost += (u64) attr->max_entries * cost_per_node; if (cost >= U32_MAX - PAGE_SIZE) { ret = -E2BIG; goto out_err; } trie->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; ret = bpf_map_precharge_memlock(trie->map.pages); if (ret) goto out_err; raw_spin_lock_init(&trie->lock); return &trie->map; out_err: kfree(trie); return ERR_PTR(ret); } static void trie_free(struct bpf_map *map) { struct lpm_trie *trie = container_of(map, struct lpm_trie, map); struct lpm_trie_node __rcu **slot; struct lpm_trie_node *node; /* Wait for outstanding programs to complete * update/lookup/delete/get_next_key and free the trie. */ synchronize_rcu(); /* Always start at the root and walk down to a node that has no * children. Then free that node, nullify its reference in the parent * and start over. */ for (;;) { slot = &trie->root; for (;;) { node = rcu_dereference_protected(*slot, 1); if (!node) goto out; if (rcu_access_pointer(node->child[0])) { slot = &node->child[0]; continue; } if (rcu_access_pointer(node->child[1])) { slot = &node->child[1]; continue; } kfree(node); RCU_INIT_POINTER(*slot, NULL); break; } } out: kfree(trie); } static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) { struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root; struct lpm_trie *trie = container_of(map, struct lpm_trie, map); struct bpf_lpm_trie_key *key = _key, *next_key = _next_key; struct lpm_trie_node **node_stack = NULL; int err = 0, stack_ptr = -1; unsigned int next_bit; size_t matchlen; /* The get_next_key follows postorder. For the 4 node example in * the top of this file, the trie_get_next_key() returns the following * one after another: * 192.168.0.0/24 * 192.168.1.0/24 * 192.168.128.0/24 * 192.168.0.0/16 * * The idea is to return more specific keys before less specific ones. */ /* Empty trie */ search_root = rcu_dereference(trie->root); if (!search_root) return -ENOENT; /* For invalid key, find the leftmost node in the trie */ if (!key || key->prefixlen > trie->max_prefixlen) goto find_leftmost; node_stack = kmalloc_array(trie->max_prefixlen, sizeof(struct lpm_trie_node *), GFP_ATOMIC | __GFP_NOWARN); if (!node_stack) return -ENOMEM; /* Try to find the exact node for the given key */ for (node = search_root; node;) { node_stack[++stack_ptr] = node; matchlen = longest_prefix_match(trie, node, key); if (node->prefixlen != matchlen || node->prefixlen == key->prefixlen) break; next_bit = extract_bit(key->data, node->prefixlen); node = rcu_dereference(node->child[next_bit]); } if (!node || node->prefixlen != key->prefixlen || (node->flags & LPM_TREE_NODE_FLAG_IM)) goto find_leftmost; /* The node with the exactly-matching key has been found, * find the first node in postorder after the matched node. */ node = node_stack[stack_ptr]; while (stack_ptr > 0) { parent = node_stack[stack_ptr - 1]; if (rcu_dereference(parent->child[0]) == node) { search_root = rcu_dereference(parent->child[1]); if (search_root) goto find_leftmost; } if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) { next_node = parent; goto do_copy; } node = parent; stack_ptr--; } /* did not find anything */ err = -ENOENT; goto free_stack; find_leftmost: /* Find the leftmost non-intermediate node, all intermediate nodes * have exact two children, so this function will never return NULL. */ for (node = search_root; node;) { if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) next_node = node; node = rcu_dereference(node->child[0]); } do_copy: next_key->prefixlen = next_node->prefixlen; memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key, data), next_node->data, trie->data_size); free_stack: kfree(node_stack); return err; } static int trie_check_btf(const struct bpf_map *map, const struct btf_type *key_type, const struct btf_type *value_type) { /* Keys must have struct bpf_lpm_trie_key embedded. */ return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ? -EINVAL : 0; } const struct bpf_map_ops trie_map_ops = { .map_alloc = trie_alloc, .map_free = trie_free, .map_get_next_key = trie_get_next_key, .map_lookup_elem = trie_lookup_elem, .map_update_elem = trie_update_elem, .map_delete_elem = trie_delete_elem, .map_check_btf = trie_check_btf, };
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