From fd8db07705c55a995c42b1e71afc42faad675b0b Mon Sep 17 00:00:00 2001
From: Florian Lehner <dev@der-flo.net>
Date: Sat, 15 Jun 2024 12:11:58 +0200
Subject: [PATCH] bpf, devmap: Add .map_alloc_check
Use the .map_allock_check callback to perform allocation checks before
allocating memory for the devmap.
Signed-off-by: Florian Lehner <dev@der-flo.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240615101158.57889-1-dev@der-flo.net
---
kernel/bpf/devmap.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 7f3b34452243c..da1fec906b96d 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -107,7 +107,7 @@ static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
}
-static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
+static int dev_map_alloc_check(union bpf_attr *attr)
{
u32 valsize = attr->value_size;
@@ -121,23 +121,28 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
attr->map_flags & ~DEV_CREATE_FLAG_MASK)
return -EINVAL;
+ if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
+ /* Hash table size must be power of 2; roundup_pow_of_two()
+ * can overflow into UB on 32-bit arches
+ */
+ if (attr->max_entries > 1UL << 31)
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
+{
/* Lookup returns a pointer straight to dev->ifindex, so make sure the
* verifier prevents writes from the BPF side
*/
attr->map_flags |= BPF_F_RDONLY_PROG;
-
-
bpf_map_init_from_attr(&dtab->map, attr);
if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
- /* hash table size must be power of 2; roundup_pow_of_two() can
- * overflow into UB on 32-bit arches, so check that first
- */
- if (dtab->map.max_entries > 1UL << 31)
- return -EINVAL;
-
+ /* Hash table size must be power of 2 */
dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
-
dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
dtab->map.numa_node);
if (!dtab->dev_index_head)
@@ -1040,6 +1045,7 @@ static u64 dev_map_mem_usage(const struct bpf_map *map)
BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
const struct bpf_map_ops dev_map_ops = {
.map_meta_equal = bpf_map_meta_equal,
+ .map_alloc_check = dev_map_alloc_check,
.map_alloc = dev_map_alloc,
.map_free = dev_map_free,
.map_get_next_key = dev_map_get_next_key,
@@ -1054,6 +1060,7 @@ const struct bpf_map_ops dev_map_ops = {
const struct bpf_map_ops dev_map_hash_ops = {
.map_meta_equal = bpf_map_meta_equal,
+ .map_alloc_check = dev_map_alloc_check,
.map_alloc = dev_map_alloc,
.map_free = dev_map_free,
.map_get_next_key = dev_map_hash_get_next_key,
--
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