Commit 485ec51e authored by Joanne Koong's avatar Joanne Koong Committed by Alexei Starovoitov
Browse files

bpf: Refactor verifier dynptr into get_dynptr_arg_reg 



This commit refactors the logic for determining which register in a
function is the dynptr into "get_dynptr_arg_reg". This will be used
in the future when the dynptr reg for BPF_FUNC_dynptr_write will need
to be obtained in order to support writes for skb dynptrs.

Signed-off-by: default avatarJoanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/r/20230301154953.641654-6-joannelkoong@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 8357b366

kernel/bpf/verifier.c

+50 −30
Original line number Diff line number Diff line
@@ -6689,6 +6689,28 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env, 
	}

}









static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env,









						const struct bpf_func_proto *fn,









						struct bpf_reg_state *regs)









{









	struct bpf_reg_state *state = NULL;









	int i;

















	for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)









		if (arg_type_is_dynptr(fn->arg_type[i])) {









			if (state) {









				verbose(env, "verifier internal error: multiple dynptr args\n");









				return NULL;









			}









			state = &regs[BPF_REG_1 + i];









		}

















	if (!state)









		verbose(env, "verifier internal error: no dynptr arg found\n");

















	return state;









}

















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









{









	struct bpf_func_state *state = func(env, reg);








@@ -8326,16 +8348,19 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn







		}









		break;









	case BPF_FUNC_dynptr_data:









		for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {









			if (arg_type_is_dynptr(fn->arg_type[i])) {









				struct bpf_reg_state *reg = &regs[BPF_REG_1 + i];









	{









		struct bpf_reg_state *reg;









		int id, ref_obj_id;

















		reg = get_dynptr_arg_reg(env, fn, regs);









		if (!reg)









			return -EFAULT;

























		if (meta.dynptr_id) {









			verbose(env, "verifier internal error: meta.dynptr_id already set\n");









			return -EFAULT;









		}

















		if (meta.ref_obj_id) {









			verbose(env, "verifier internal error: meta.ref_obj_id already set\n");









			return -EFAULT;








@@ -8355,14 +8380,9 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn















		meta.dynptr_id = id;









		meta.ref_obj_id = ref_obj_id;

















		break;









	}









		}









		if (i == MAX_BPF_FUNC_REG_ARGS) {









			verbose(env, "verifier internal error: no dynptr in bpf_dynptr_data()\n");









			return -EFAULT;









		}









		break;









	case BPF_FUNC_user_ringbuf_drain:









		err = __check_func_call(env, insn, insn_idx_p, meta.subprogno,









					set_user_ringbuf_callback_state);