[PATCH bpf-next 5/9] bpf: Allow registration of const cfi_stubs

From: Thomas Weißschuh
Date: Wed Nov 27 2024 - 14:21:36 EST


The BPF core does not need to modify the cfi_stubs.
Reflect this in the API so users can move their structures into
read-only memory.

Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
include/linux/bpf.h | 2 +-
kernel/bpf/bpf_struct_ops.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a9267af9671b2bc8961cde24d2f79f473ab227d7..fbe5ae7c2b380fdb624ea1f04fdf56e4f6710f14 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1795,7 +1795,7 @@ struct bpf_struct_ops {
void (*unreg)(void *kdata, struct bpf_link *link);
int (*update)(void *kdata, void *old_kdata, struct bpf_link *link);
int (*validate)(void *kdata);
- void *cfi_stubs;
+ const void *cfi_stubs;
struct module *owner;
const char *name;
};
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 967f0914d473fcde4a6ce3bb6ac976345daf8e88..2a9b9c39f1e7c2c22dc83ad68766b522117f3979 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -778,7 +778,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
trampoline_start = image_off;
err = bpf_struct_ops_prepare_trampoline(tlinks, link,
&st_ops_desc->func_models[i],
- *(void **)(st_ops->cfi_stubs + moff),
+ *(void *const *)(st_ops->cfi_stubs + moff),
&image, &image_off,
st_map->image_pages_cnt < MAX_TRAMP_IMAGE_PAGES);
if (err)

--
2.47.1