Commit 76145f72 authored by Anton Protopopov's avatar Anton Protopopov Committed by Andrii Nakryiko
Browse files

bpf: Refactor check_pseudo_btf_id 



Introduce a helper to add btfs to the env->used_maps array. Use it
to simplify the check_pseudo_btf_id() function. This new helper will
also be re-used in a consequent patch.

Signed-off-by: default avatarAnton Protopopov <aspsk@isovalent.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241213130934.1087929-4-aspsk@isovalent.com
parent 928f3221

kernel/bpf/verifier.c

+76 −56
Original line number Diff line number Diff line
@@ -19218,50 +19218,68 @@ static int find_btf_percpu_datasec(struct btf *btf) 
	return -ENOENT;

}









/*









 * Add btf to the used_btfs array and return the index. (If the btf was









 * already added, then just return the index.) Upon successful insertion









 * increase btf refcnt, and, if present, also refcount the corresponding









 * kernel module.









 */









static int __add_used_btf(struct bpf_verifier_env *env, struct btf *btf)









{









	struct btf_mod_pair *btf_mod;









	int i;

















	/* check whether we recorded this BTF (and maybe module) already */









	for (i = 0; i < env->used_btf_cnt; i++)









		if (env->used_btfs[i].btf == btf)









			return i;

















	if (env->used_btf_cnt >= MAX_USED_BTFS)









		return -E2BIG;

















	btf_get(btf);

















	btf_mod = &env->used_btfs[env->used_btf_cnt];









	btf_mod->btf = btf;









	btf_mod->module = NULL;

















	/* if we reference variables from kernel module, bump its refcount */









	if (btf_is_module(btf)) {









		btf_mod->module = btf_try_get_module(btf);









		if (!btf_mod->module) {









			btf_put(btf);









			return -ENXIO;









		}









	}

















	return env->used_btf_cnt++;









}

















/* replace pseudo btf_id with kernel symbol address */









static int check_pseudo_btf_id(struct bpf_verifier_env *env,









static int __check_pseudo_btf_id(struct bpf_verifier_env *env,









				 struct bpf_insn *insn,









			       struct bpf_insn_aux_data *aux)









				 struct bpf_insn_aux_data *aux,









				 struct btf *btf)









{









	const struct btf_var_secinfo *vsi;









	const struct btf_type *datasec;









	struct btf_mod_pair *btf_mod;









	const struct btf_type *t;









	const char *sym_name;









	bool percpu = false;









	u32 type, id = insn->imm;









	struct btf *btf;









	s32 datasec_id;









	u64 addr;









	int i, btf_fd, err;

















	btf_fd = insn[1].imm;









	if (btf_fd) {









		btf = btf_get_by_fd(btf_fd);









		if (IS_ERR(btf)) {









			verbose(env, "invalid module BTF object FD specified.\n");









			return -EINVAL;









		}









	} else {









		if (!btf_vmlinux) {









			verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");









			return -EINVAL;









		}









		btf = btf_vmlinux;









		btf_get(btf);









	}









	int i;

















	t = btf_type_by_id(btf, id);









	if (!t) {









		verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id);









		err = -ENOENT;









		goto err_put;









		return -ENOENT;









	}

















	if (!btf_type_is_var(t) && !btf_type_is_func(t)) {









		verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR or KIND_FUNC\n", id);









		err = -EINVAL;









		goto err_put;









		return -EINVAL;









	}

















	sym_name = btf_name_by_offset(btf, t->name_off);








@@ -19269,8 +19287,7 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,







	if (!addr) {









		verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n",









			sym_name);









		err = -ENOENT;









		goto err_put;









		return -ENOENT;









	}









	insn[0].imm = (u32)addr;









	insn[1].imm = addr >> 32;








@@ -19278,7 +19295,7 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,







	if (btf_type_is_func(t)) {









		aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;









		aux->btf_var.mem_size = 0;









		goto check_btf;









		return 0;









	}

















	datasec_id = find_btf_percpu_datasec(btf);








@@ -19309,8 +19326,7 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,







			tname = btf_name_by_offset(btf, t->name_off);









			verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n",









				tname, PTR_ERR(ret));









			err = -EINVAL;









			goto err_put;









			return -EINVAL;









		}









		aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;









		aux->btf_var.mem_size = tsize;








@@ -19319,39 +19335,43 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,







		aux->btf_var.btf = btf;









		aux->btf_var.btf_id = type;









	}









check_btf:









	/* check whether we recorded this BTF (and maybe module) already */









	for (i = 0; i < env->used_btf_cnt; i++) {









		if (env->used_btfs[i].btf == btf) {









			btf_put(btf);

















	return 0;









}









	}

















	if (env->used_btf_cnt >= MAX_USED_BTFS) {









		err = -E2BIG;









		goto err_put;









	}









static int check_pseudo_btf_id(struct bpf_verifier_env *env,









			       struct bpf_insn *insn,









			       struct bpf_insn_aux_data *aux)









{









	struct btf *btf;









	int btf_fd;









	int err;

















	btf_mod = &env->used_btfs[env->used_btf_cnt];









	btf_mod->btf = btf;









	btf_mod->module = NULL;









	btf_fd = insn[1].imm;









	if (btf_fd) {









		CLASS(fd, f)(btf_fd);

















	/* if we reference variables from kernel module, bump its refcount */









	if (btf_is_module(btf)) {









		btf_mod->module = btf_try_get_module(btf);









		if (!btf_mod->module) {









			err = -ENXIO;









			goto err_put;









		btf = __btf_get_by_fd(f);









		if (IS_ERR(btf)) {









			verbose(env, "invalid module BTF object FD specified.\n");









			return -EINVAL;









		}









	} else {









		if (!btf_vmlinux) {









			verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");









			return -EINVAL;









		}









		btf = btf_vmlinux;









	}

















	env->used_btf_cnt++;









	err = __check_pseudo_btf_id(env, insn, aux, btf);









	if (err)









		return err;

















	return 0;









err_put:









	btf_put(btf);









	err = __add_used_btf(env, btf);









	if (err < 0)









		return err;









	return 0;









}

















static bool is_tracing_prog_type(enum bpf_prog_type type)