Mark the trampoline as RO+X after arch_prepare_bpf_trampoline, so that
the trampoine follows W^X rule strictly. This will turn off warnings like
CPA refuse W^X violation: 8000000000000163 -> 0000000000000163 range: ...
Also remove bpf_jit_alloc_exec_page(), since it is not used any more.
Signed-off-by: Song Liu <song@xxxxxxxxxx>
---
include/linux/bpf.h | 1 -
kernel/bpf/trampoline.c | 22 +++++-----------------
2 files changed, 5 insertions(+), 18 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a8d0cfe14372..44a3d6b3c924 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1008,7 +1008,6 @@ int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs);
void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from,
struct bpf_prog *to);
/* Called only from JIT-enabled code, so there's no need for stubs. */
-void *bpf_jit_alloc_exec_page(void);
void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym);
void bpf_image_ksym_del(struct bpf_ksym *ksym);
void bpf_ksym_add(struct bpf_ksym *ksym);
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 41b67eb83ab3..6f7b939321d6 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -116,22 +116,6 @@ bool bpf_prog_has_trampoline(const struct bpf_prog *prog)
(ptype == BPF_PROG_TYPE_LSM && eatype == BPF_LSM_MAC);
}
-void *bpf_jit_alloc_exec_page(void)
-{
- void *image;
-
- image = bpf_jit_alloc_exec(PAGE_SIZE);
- if (!image)
- return NULL;
-
- set_vm_flush_reset_perms(image);
- /* Keep image as writeable. The alternative is to keep flipping ro/rw
- * every time new program is attached or detached.
- */
- set_memory_x((long)image, 1);
- return image;
-}
-
void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym)
{
ksym->start = (unsigned long) data;
@@ -404,9 +388,10 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx)
goto out_free_im;
err = -ENOMEM;
- im->image = image = bpf_jit_alloc_exec_page();
+ im->image = image = bpf_jit_alloc_exec(PAGE_SIZE);
if (!image)
goto out_uncharge;
+ set_vm_flush_reset_perms(image);
err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL);
if (err)
@@ -483,6 +468,9 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
if (err < 0)
goto out;
+ set_memory_ro((long)im->image, 1);
+ set_memory_x((long)im->image, 1);
+
WARN_ON(tr->cur_image && tr->selector == 0);
WARN_ON(!tr->cur_image && tr->selector);
if (tr->cur_image)
--
2.30.2
