This is a small bugfix for LPM trie.
Hou Tao (2): bpf: Handle BPF_EXIST and BPF_NOEXIST for LPM trie bpf: Handle in-place update for full LPM trie correctly
kernel/bpf/lpm_trie.c | 44 +++++++++++++++++++++++++++++-------------- 1 file changed, 30 insertions(+), 14 deletions(-)
From: Hou Tao houtao1@huawei.com
stable inclusion from stable-v5.10.231 commit adb4a970bfa96dd4bfc4e623a07e3dbefc3c8aab category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBFB6E
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ Upstream commit eae6a075e9537dd69891cf77ca5a88fa8a28b4a1 ]
Add the currently missing handling for the BPF_EXIST and BPF_NOEXIST flags. These flags can be specified by users and are relevant since LPM trie supports exact matches during update.
Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation") Reviewed-by: Toke Høiland-Jørgensen toke@redhat.com Acked-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Hou Tao houtao1@huawei.com Link: https://lore.kernel.org/r/20241206110622.1161752-4-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Tengda Wu wutengda2@huawei.com --- kernel/bpf/lpm_trie.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 8370b391f1d6..07f11f108f6a 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -364,6 +364,10 @@ static int trie_update_elem(struct bpf_map *map, * simply assign the @new_node to that slot and be done. */ if (!node) { + if (flags == BPF_EXIST) { + ret = -ENOENT; + goto out; + } rcu_assign_pointer(*slot, new_node); goto out; } @@ -372,18 +376,31 @@ static int trie_update_elem(struct bpf_map *map, * which already has the correct data array set. */ if (node->prefixlen == matchlen) { + if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) { + if (flags == BPF_NOEXIST) { + ret = -EEXIST; + goto out; + } + trie->n_entries--; + } else if (flags == BPF_EXIST) { + ret = -ENOENT; + goto out; + } + 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 (flags == BPF_EXIST) { + ret = -ENOENT; + goto out; + } + /* If the new node matches the prefix completely, it must be inserted * as an ancestor. Simply insert it between @node and *@slot. */
From: Hou Tao houtao1@huawei.com
mainline inclusion from mainline-v6.13-rc2 commit 532d6b36b2bfac5514426a97a4df8d103d700d43 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBFB6E
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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When a LPM trie is full, in-place updates of existing elements incorrectly return -ENOSPC.
Fix this by deferring the check of trie->n_entries. For new insertions, n_entries must not exceed max_entries. However, in-place updates are allowed even when the trie is full.
Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation") Reviewed-by: Toke Høiland-Jørgensen toke@redhat.com Signed-off-by: Hou Tao houtao1@huawei.com Link: https://lore.kernel.org/r/20241206110622.1161752-5-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov ast@kernel.org Conflicts: kernel/bpf/lpm_trie.c [The cleanup patch 3d5611b4d7ef did not backport, causing conflicts] Signed-off-by: Tengda Wu wutengda2@huawei.com --- kernel/bpf/lpm_trie.c | 41 ++++++++++++++++++++--------------------- 1 file changed, 20 insertions(+), 21 deletions(-)
diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 07f11f108f6a..e4817e2d01cb 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -299,6 +299,16 @@ static struct lpm_trie_node *lpm_trie_node_alloc(const struct lpm_trie *trie, return node; }
+static int trie_check_add_elem(struct lpm_trie *trie, u64 flags) +{ + if (flags == BPF_EXIST) + return -ENOENT; + if (trie->n_entries == trie->map.max_entries) + return -ENOSPC; + trie->n_entries++; + return 0; +} + /* Called from syscall or from eBPF program */ static int trie_update_elem(struct bpf_map *map, void *_key, void *value, u64 flags) @@ -321,20 +331,12 @@ static int trie_update_elem(struct bpf_map *map, 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); @@ -364,10 +366,10 @@ static int trie_update_elem(struct bpf_map *map, * simply assign the @new_node to that slot and be done. */ if (!node) { - if (flags == BPF_EXIST) { - ret = -ENOENT; + ret = trie_check_add_elem(trie, flags); + if (ret) goto out; - } + rcu_assign_pointer(*slot, new_node); goto out; } @@ -381,10 +383,10 @@ static int trie_update_elem(struct bpf_map *map, ret = -EEXIST; goto out; } - trie->n_entries--; - } else if (flags == BPF_EXIST) { - ret = -ENOENT; - goto out; + } else { + ret = trie_check_add_elem(trie, flags); + if (ret) + goto out; }
new_node->child[0] = node->child[0]; @@ -396,10 +398,9 @@ static int trie_update_elem(struct bpf_map *map, goto out; }
- if (flags == BPF_EXIST) { - ret = -ENOENT; + ret = trie_check_add_elem(trie, flags); + if (ret) goto out; - }
/* If the new node matches the prefix completely, it must be inserted * as an ancestor. Simply insert it between @node and *@slot. @@ -413,6 +414,7 @@ static int trie_update_elem(struct bpf_map *map,
im_node = lpm_trie_node_alloc(trie, NULL); if (!im_node) { + trie->n_entries--; ret = -ENOMEM; goto out; } @@ -435,9 +437,6 @@ static int trie_update_elem(struct bpf_map *map,
out: if (ret) { - if (new_node) - trie->n_entries--; - kfree(new_node); kfree(im_node); }
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