Commit a461f5ad authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

bpf: generalize dynptr_get_spi to be usable for iters 



Generalize the logic of fetching special stack slot object state using
spi (stack slot index). This will be used by STACK_ITER logic next.

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230302235015.2044271-12-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d5271c5b

kernel/bpf/verifier.c

+12 −6
Original line number Diff line number Diff line
@@ -710,32 +710,38 @@ static bool is_spi_bounds_valid(struct bpf_func_state *state, int spi, int nr_sl 
       return spi - nr_slots + 1 >= 0 && spi < allocated_slots;

}









static int dynptr_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg)









static int stack_slot_obj_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg,









			          const char *obj_kind, int nr_slots)









{









	int off, spi;

















	if (!tnum_is_const(reg->var_off)) {









		verbose(env, "dynptr has to be at a constant offset\n");









		verbose(env, "%s has to be at a constant offset\n", obj_kind);









		return -EINVAL;









	}

















	off = reg->off + reg->var_off.value;









	if (off % BPF_REG_SIZE) {









		verbose(env, "cannot pass in dynptr at an offset=%d\n", off);









		verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);









		return -EINVAL;









	}

















	spi = __get_spi(off);









	if (spi < 1) {









		verbose(env, "cannot pass in dynptr at an offset=%d\n", off);









	if (spi + 1 < nr_slots) {









		verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);









		return -EINVAL;









	}

















	if (!is_spi_bounds_valid(func(env, reg), spi, BPF_DYNPTR_NR_SLOTS))









	if (!is_spi_bounds_valid(func(env, reg), spi, nr_slots))









		return -ERANGE;









	return spi;









}

















static int dynptr_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg)









{









	return stack_slot_obj_get_spi(env, reg, "dynptr", BPF_DYNPTR_NR_SLOTS);









}

















static const char *kernel_type_name(const struct btf* btf, u32 id)









{









	return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off);