bpf: Remove check_kfunc_call callback and old kfunc BTF ID API

Completely remove the old code for check_kfunc_call to help it work
with modules, and also the callback itself.

The previous commit adds infrastructure to register all sets and put
them in vmlinux or module BTF, and concatenates all related sets
organized by the hook and the type. Once populated, these sets remain
immutable for the lifetime of the struct btf.

Also, since we don't need the 'owner' module anywhere when doing
check_kfunc_call, drop the 'btf_modp' module parameter from
find_kfunc_desc_btf.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220114163953.1455836-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 8 insertions, 58 deletions

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 74037bd65d17..4be5cf629ca9 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6682,52 +6682,6 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
 }
 EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set);
 
-#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
-
-void register_kfunc_btf_id_set(struct kfunc_btf_id_list *l,
-			       struct kfunc_btf_id_set *s)
-{
-	mutex_lock(&l->mutex);
-	list_add(&s->list, &l->list);
-	mutex_unlock(&l->mutex);
-}
-EXPORT_SYMBOL_GPL(register_kfunc_btf_id_set);
-
-void unregister_kfunc_btf_id_set(struct kfunc_btf_id_list *l,
-				 struct kfunc_btf_id_set *s)
-{
-	mutex_lock(&l->mutex);
-	list_del_init(&s->list);
-	mutex_unlock(&l->mutex);
-}
-EXPORT_SYMBOL_GPL(unregister_kfunc_btf_id_set);
-
-bool bpf_check_mod_kfunc_call(struct kfunc_btf_id_list *klist, u32 kfunc_id,
-			      struct module *owner)
-{
-	struct kfunc_btf_id_set *s;
-
-	mutex_lock(&klist->mutex);
-	list_for_each_entry(s, &klist->list, list) {
-		if (s->owner == owner && btf_id_set_contains(s->set, kfunc_id)) {
-			mutex_unlock(&klist->mutex);
-			return true;
-		}
-	}
-	mutex_unlock(&klist->mutex);
-	return false;
-}
-
-#define DEFINE_KFUNC_BTF_ID_LIST(name)                                         \
-	struct kfunc_btf_id_list name = { LIST_HEAD_INIT(name.list),           \
-					  __MUTEX_INITIALIZER(name.mutex) };   \
-	EXPORT_SYMBOL_GPL(name)
-
-DEFINE_KFUNC_BTF_ID_LIST(bpf_tcp_ca_kfunc_list);
-DEFINE_KFUNC_BTF_ID_LIST(prog_test_kfunc_list);
-
-#endif
-
 int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
 			      const struct btf *targ_btf, __u32 targ_id)
 {
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bfb45381fb3f..72802c1eb5ac 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1741,7 +1741,7 @@ find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset)
 }
 
 static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env,
-					 s16 offset, struct module **btf_modp)
+					 s16 offset)
 {
 	struct bpf_kfunc_btf kf_btf = { .offset = offset };
 	struct bpf_kfunc_btf_tab *tab;
@@ -1795,8 +1795,6 @@ static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env,
 		sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
 		     kfunc_btf_cmp_by_off, NULL);
 	}
-	if (btf_modp)
-		*btf_modp = b->module;
 	return b->btf;
 }
 
@@ -1813,8 +1811,7 @@ void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab)
 }
 
 static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env,
-				       u32 func_id, s16 offset,
-				       struct module **btf_modp)
+				       u32 func_id, s16 offset)
 {
 	if (offset) {
 		if (offset < 0) {
@@ -1825,7 +1822,7 @@ static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env,
 			return ERR_PTR(-EINVAL);
 		}
 
-		return __find_kfunc_desc_btf(env, offset, btf_modp);
+		return __find_kfunc_desc_btf(env, offset);
 	}
 	return btf_vmlinux ?: ERR_PTR(-ENOENT);
 }
@@ -1888,7 +1885,7 @@ static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset)
 		prog_aux->kfunc_btf_tab = btf_tab;
 	}
 
-	desc_btf = find_kfunc_desc_btf(env, func_id, offset, NULL);
+	desc_btf = find_kfunc_desc_btf(env, func_id, offset);
 	if (IS_ERR(desc_btf)) {
 		verbose(env, "failed to find BTF for kernel function\n");
 		return PTR_ERR(desc_btf);
@@ -2349,7 +2346,7 @@ static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn)
 	if (insn->src_reg != BPF_PSEUDO_KFUNC_CALL)
 		return NULL;
 
-	desc_btf = find_kfunc_desc_btf(data, insn->imm, insn->off, NULL);
+	desc_btf = find_kfunc_desc_btf(data, insn->imm, insn->off);
 	if (IS_ERR(desc_btf))
 		return "<error>";
 
@@ -6820,7 +6817,6 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn)
 	struct bpf_reg_state *regs = cur_regs(env);
 	const char *func_name, *ptr_type_name;
 	u32 i, nargs, func_id, ptr_type_id;
-	struct module *btf_mod = NULL;
 	const struct btf_param *args;
 	struct btf *desc_btf;
 	int err;
@@ -6829,7 +6825,7 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn)
 	if (!insn->imm)
 		return 0;
 
-	desc_btf = find_kfunc_desc_btf(env, insn->imm, insn->off, &btf_mod);
+	desc_btf = find_kfunc_desc_btf(env, insn->imm, insn->off);
 	if (IS_ERR(desc_btf))
 		return PTR_ERR(desc_btf);
 
@@ -6838,8 +6834,8 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn)
 	func_name = btf_name_by_offset(desc_btf, func->name_off);
 	func_proto = btf_type_by_id(desc_btf, func->type);
 
-	if (!env->ops->check_kfunc_call ||
-	    !env->ops->check_kfunc_call(func_id, btf_mod)) {
+	if (!btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog),
+				      BTF_KFUNC_TYPE_CHECK, func_id)) {
 		verbose(env, "calling kernel function %s is not allowed\n",
 			func_name);
 		return -EACCES;