bpf: Constify struct btf_kind_operations

struct btf_kind_operations are not modified in BTF.

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@wanadoo.fr>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/9192ab72b2e9c66aefd6520f359a20297186327f.1726417289.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 75e4fe83c509107374db4651b26f9512b3b45b93..13dd1fa1d1b97cb1862726237718cb09e39662cb 100644 (file)
--- 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 @@ done:
        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,