The task of calculating bpf_dynptr_kern's available size, and the
current (offset) data pointer is common for BPF functions working with
ARG_PTR_TO_DYNPTR parameters.
Introduce 'bpf_dynptr_get_data' which returns the current data
(with properer offset), and the number of usable bytes it has.
This will void callers from directly calculating bpf_dynptr_kern's
data, offset and size.
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@xxxxxxxxx>
---
include/linux/bpf.h | 1 +
kernel/bpf/helpers.c | 10 ++++++++++
2 files changed, 11 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 39bd36359c1e..6d288dfc302b 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2576,6 +2576,7 @@ void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
enum bpf_dynptr_type type, u32 offset, u32 size);
void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr);
int bpf_dynptr_check_size(u32 size);
+void *bpf_dynptr_get_data(struct bpf_dynptr_kern *ptr, u32 *avail_bytes);
#ifdef CONFIG_BPF_LSM
void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype);
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 3c1b9bbcf971..91f406a9c37f 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1461,6 +1461,16 @@ void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
bpf_dynptr_set_type(ptr, type);
}
+void *bpf_dynptr_get_data(struct bpf_dynptr_kern *ptr, u32 *avail_bytes)
+{
+ u32 size = bpf_dynptr_get_size(ptr);
+
+ if (!ptr->data || ptr->offset > size)
+ return NULL;
+ *avail_bytes = size - ptr->offset;
+ return ptr->data + ptr->offset;
+}
+
void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr)
{
memset(ptr, 0, sizeof(*ptr));
--
2.37.2
