[PATCH] bpf: Constify struct btf_kind_operations

From: Christophe JAILLET
Date: Sun Sep 15 2024 - 12:22:30 EST


'struct btf_kind_operations' are not modified in this driver.

Constifying this structures moves some data to a read-only section, so
increase overall security, especially when the structure holds some
function pointers.

On a x86_64, with allmodconfig:
Before:
======
text data bss dec hex filename
184320 7091 548 191959 2edd7 kernel/bpf/btf.o

After:
=====
text data bss dec hex filename
184896 6515 548 191959 2edd7 kernel/bpf/btf.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
Compile tested-only.
---
kernel/bpf/btf.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index d2f87db9131e..432eda0f6550 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -2808,7 +2808,7 @@ static void btf_ref_type_log(struct btf_verifier_env *env,
btf_verifier_log(env, "type_id=%u", t->type);
}

-static struct btf_kind_operations modifier_ops = {
+static const struct btf_kind_operations modifier_ops = {
.check_meta = btf_ref_type_check_meta,
.resolve = btf_modifier_resolve,
.check_member = btf_modifier_check_member,
@@ -2817,7 +2817,7 @@ static struct btf_kind_operations modifier_ops = {
.show = btf_modifier_show,
};

-static struct btf_kind_operations ptr_ops = {
+static const struct btf_kind_operations ptr_ops = {
.check_meta = btf_ref_type_check_meta,
.resolve = btf_ptr_resolve,
.check_member = btf_ptr_check_member,
@@ -2858,7 +2858,7 @@ static void btf_fwd_type_log(struct btf_verifier_env *env,
btf_verifier_log(env, "%s", btf_type_kflag(t) ? "union" : "struct");
}

-static struct btf_kind_operations fwd_ops = {
+static const struct btf_kind_operations fwd_ops = {
.check_meta = btf_fwd_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_df_check_member,
@@ -3109,7 +3109,7 @@ static void btf_array_show(const struct btf *btf, const struct btf_type *t,
__btf_array_show(btf, t, type_id, data, bits_offset, show);
}

-static struct btf_kind_operations array_ops = {
+static const struct btf_kind_operations array_ops = {
.check_meta = btf_array_check_meta,
.resolve = btf_array_resolve,
.check_member = btf_array_check_member,
@@ -4185,7 +4185,7 @@ static void btf_struct_show(const struct btf *btf, const struct btf_type *t,
__btf_struct_show(btf, t, type_id, data, bits_offset, show);
}

-static struct btf_kind_operations struct_ops = {
+static const struct btf_kind_operations struct_ops = {
.check_meta = btf_struct_check_meta,
.resolve = btf_struct_resolve,
.check_member = btf_struct_check_member,
@@ -4353,7 +4353,7 @@ static void btf_enum_show(const struct btf *btf, const struct btf_type *t,
btf_show_end_type(show);
}

-static struct btf_kind_operations enum_ops = {
+static const struct btf_kind_operations enum_ops = {
.check_meta = btf_enum_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_enum_check_member,
@@ -4456,7 +4456,7 @@ static void btf_enum64_show(const struct btf *btf, const struct btf_type *t,
btf_show_end_type(show);
}

-static struct btf_kind_operations enum64_ops = {
+static const struct btf_kind_operations enum64_ops = {
.check_meta = btf_enum64_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_enum_check_member,
@@ -4534,7 +4534,7 @@ static void btf_func_proto_log(struct btf_verifier_env *env,
btf_verifier_log(env, ")");
}

-static struct btf_kind_operations func_proto_ops = {
+static const struct btf_kind_operations func_proto_ops = {
.check_meta = btf_func_proto_check_meta,
.resolve = btf_df_resolve,
/*
@@ -4592,7 +4592,7 @@ static int btf_func_resolve(struct btf_verifier_env *env,
return 0;
}

-static struct btf_kind_operations func_ops = {
+static const struct btf_kind_operations func_ops = {
.check_meta = btf_func_check_meta,
.resolve = btf_func_resolve,
.check_member = btf_df_check_member,
--
2.46.0