bpf: check bpf_dummy_struct_ops program params for test runs
When doing BPF_PROG_TEST_RUN for bpf_dummy_struct_ops programs, reject execution when NULL is passed for non-nullable params. For programs with non-nullable params verifier assumes that such params are never NULL and thus might optimize out NULL checks. Suggested-by: Kui-Feng Lee <sinquersw@gmail.com> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240424012821.595216-5-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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@ -79,6 +79,51 @@ static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args)
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args->args[3], args->args[4]);
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}
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static const struct bpf_ctx_arg_aux *find_ctx_arg_info(struct bpf_prog_aux *aux, int offset)
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{
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int i;
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for (i = 0; i < aux->ctx_arg_info_size; i++)
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if (aux->ctx_arg_info[i].offset == offset)
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return &aux->ctx_arg_info[i];
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return NULL;
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}
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/* There is only one check at the moment:
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* - zero should not be passed for pointer parameters not marked as nullable.
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*/
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static int check_test_run_args(struct bpf_prog *prog, struct bpf_dummy_ops_test_args *args)
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{
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const struct btf_type *func_proto = prog->aux->attach_func_proto;
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for (u32 arg_no = 0; arg_no < btf_type_vlen(func_proto) ; ++arg_no) {
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const struct btf_param *param = &btf_params(func_proto)[arg_no];
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const struct bpf_ctx_arg_aux *info;
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const struct btf_type *t;
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int offset;
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if (args->args[arg_no] != 0)
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continue;
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/* Program is validated already, so there is no need
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* to check if t is NULL.
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*/
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t = btf_type_skip_modifiers(bpf_dummy_ops_btf, param->type, NULL);
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if (!btf_type_is_ptr(t))
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continue;
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offset = btf_ctx_arg_offset(bpf_dummy_ops_btf, func_proto, arg_no);
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info = find_ctx_arg_info(prog->aux, offset);
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if (info && (info->reg_type & PTR_MAYBE_NULL))
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continue;
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return -EINVAL;
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}
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return 0;
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}
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extern const struct bpf_link_ops bpf_struct_ops_link_lops;
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int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
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@ -87,7 +132,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
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const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
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const struct btf_type *func_proto;
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struct bpf_dummy_ops_test_args *args;
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struct bpf_tramp_links *tlinks;
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struct bpf_tramp_links *tlinks = NULL;
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struct bpf_tramp_link *link = NULL;
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void *image = NULL;
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unsigned int op_idx;
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@ -109,6 +154,10 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
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if (IS_ERR(args))
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return PTR_ERR(args);
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err = check_test_run_args(prog, args);
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if (err)
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goto out;
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tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL);
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if (!tlinks) {
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err = -ENOMEM;
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