From: Hou Tao <houtao1@xxxxxxxxxx>
Introduce bpf_mem_alloc_check_size() to check whether the allocation
size exceeds the limitation for the kmalloc-equivalent allocator. The
upper limit for percpu allocation is LLIST_NODE_SZ bytes larger than
non-percpu allocation, so a percpu argument is added to the helper.
The helper will be used in the following patch to check whether the size
parameter passed to bpf_mem_alloc() is too big.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
include/linux/bpf_mem_alloc.h | 3 +++
kernel/bpf/memalloc.c | 14 +++++++++++++-
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/include/linux/bpf_mem_alloc.h b/include/linux/bpf_mem_alloc.h
index aaf004d94322..e45162ef59bb 100644
--- a/include/linux/bpf_mem_alloc.h
+++ b/include/linux/bpf_mem_alloc.h
@@ -33,6 +33,9 @@ int bpf_mem_alloc_percpu_init(struct bpf_mem_alloc *ma, struct obj_cgroup *objcg
int bpf_mem_alloc_percpu_unit_init(struct bpf_mem_alloc *ma, int size);
void bpf_mem_alloc_destroy(struct bpf_mem_alloc *ma);
+/* Check the allocation size for kmalloc equivalent allocator */
+int bpf_mem_alloc_check_size(bool percpu, size_t size);
+
/* kmalloc/kfree equivalent: */
void *bpf_mem_alloc(struct bpf_mem_alloc *ma, size_t size);
void bpf_mem_free(struct bpf_mem_alloc *ma, void *ptr);
diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c
index b3858a76e0b3..146f5b57cfb1 100644
--- a/kernel/bpf/memalloc.c
+++ b/kernel/bpf/memalloc.c
@@ -35,6 +35,8 @@
*/
#define LLIST_NODE_SZ sizeof(struct llist_node)
+#define BPF_MEM_ALLOC_SIZE_MAX 4096
+
/* similar to kmalloc, but sizeof == 8 bucket is gone */
static u8 size_index[24] __ro_after_init = {
3, /* 8 */
@@ -65,7 +67,7 @@ static u8 size_index[24] __ro_after_init = {
static int bpf_mem_cache_idx(size_t size)
{
- if (!size || size > 4096)
+ if (!size || size > BPF_MEM_ALLOC_SIZE_MAX)
return -1;
if (size <= 192)
@@ -1005,3 +1007,13 @@ void notrace *bpf_mem_cache_alloc_flags(struct bpf_mem_alloc *ma, gfp_t flags)
return !ret ? NULL : ret + LLIST_NODE_SZ;
}
+
+int bpf_mem_alloc_check_size(bool percpu, size_t size)
+{
+ /* The size of percpu allocation doesn't have LLIST_NODE_SZ overhead */
+ if ((percpu && size > BPF_MEM_ALLOC_SIZE_MAX) ||
+ (!percpu && size > BPF_MEM_ALLOC_SIZE_MAX - LLIST_NODE_SZ))
+ return -E2BIG;
+
+ return 0;
+}
--
2.29.2
