From: Lorenz Bauer <lmb@cloudflare.com>
To: Martin KaFai Lau <kafai@fb.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <kernel-team@fb.com>,
Networking <netdev@vger.kernel.org>
Subject: Re: [PATCH v3 bpf-next 01/11] bpf: Move the PTR_TO_BTF_ID check to check_reg_type()
Date: Tue, 22 Sep 2020 10:56:55 +0100 [thread overview]
Message-ID: <CACAyw9_wEMFuymvUC0fsZVJCH0vsvbD9p=CWTZC1jV2gUiu3KA@mail.gmail.com> (raw)
In-Reply-To: <20200922070415.1916194-1-kafai@fb.com>
On Tue, 22 Sep 2020 at 08:04, Martin KaFai Lau <kafai@fb.com> wrote:
>
> check_reg_type() checks whether a reg can be used as an arg of a
> func_proto. For PTR_TO_BTF_ID, the check is actually not
> completely done until the reg->btf_id is pointing to a
> kernel struct that is acceptable by the func_proto.
>
> Thus, this patch moves the btf_id check into check_reg_type().
> The compatible_reg_types[] usage is localized in check_reg_type() now.
>
> The "if (!btf_id) verbose(...); " is also removed since it won't happen.
>
> Signed-off-by: Martin KaFai Lau <kafai@fb.com>
> ---
> kernel/bpf/verifier.c | 65 +++++++++++++++++++++++--------------------
> 1 file changed, 35 insertions(+), 30 deletions(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 15ab889b0a3f..3ce61c412ea0 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -4028,20 +4028,29 @@ static const struct bpf_reg_types *compatible_reg_types[] = {
> [__BPF_ARG_TYPE_MAX] = NULL,
> };
>
> -static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
> - const struct bpf_reg_types *compatible)
> +static int check_reg_type(struct bpf_verifier_env *env, u32 arg,
> + enum bpf_arg_type arg_type,
> + const struct bpf_func_proto *fn)
How about (env, regno, arg_type, expected_btf_id) instead? Otherwise
implementing sockmap update from iter with your current approach is
difficult for me. See resolve_map_arg_type, which now needs to resolve
expected_bpf_id.
See below for what I mean:
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2468533bc4a1..3a238a295c37 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3931,7 +3931,8 @@ static int int_ptr_type_to_size(enum bpf_arg_type type)
static int resolve_map_arg_type(struct bpf_verifier_env *env,
const struct bpf_call_arg_meta *meta,
- enum bpf_arg_type *arg_type)
+ enum bpf_arg_type *arg_type,
+ u32 **expected_btf_id)
{
if (!meta->map_ptr) {
/* kernel subsystem misconfigured verifier */
@@ -3943,7 +3944,8 @@ static int resolve_map_arg_type(struct
bpf_verifier_env *env,
case BPF_MAP_TYPE_SOCKMAP:
case BPF_MAP_TYPE_SOCKHASH:
if (*arg_type == ARG_PTR_TO_MAP_VALUE) {
- *arg_type = ARG_PTR_TO_SOCKET;
+ *arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON;
+ *expected_btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON];
} else {
verbose(env, "invalid arg_type for sockmap/sockhash\n");
return -EINVAL;
@@ -4044,11 +4046,9 @@ static const struct bpf_reg_types
*compatible_reg_types[] = {
[__BPF_ARG_TYPE_MAX] = NULL,
};
-static int check_reg_type(struct bpf_verifier_env *env, u32 arg,
- enum bpf_arg_type arg_type,
- const struct bpf_func_proto *fn)
+static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
+ enum bpf_arg_type arg_type, u32 *expected_btf_id)
{
- u32 regno = BPF_REG_1 + arg;
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
enum bpf_reg_type expected, type = reg->type;
const struct bpf_reg_types *compatible;
@@ -4077,8 +4077,6 @@ static int check_reg_type(struct
bpf_verifier_env *env, u32 arg,
found:
if (type == PTR_TO_BTF_ID) {
- u32 *expected_btf_id = fn->arg_btf_id[arg];
-
if (!btf_struct_ids_match(&env->log, reg->off, reg->btf_id,
*expected_btf_id)) {
verbose(env, "R%d is of type %s but %s is expected\n",
@@ -4105,6 +4103,7 @@ static int check_func_arg(struct
bpf_verifier_env *env, u32 arg,
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
enum bpf_arg_type arg_type = fn->arg_type[arg];
enum bpf_reg_type type = reg->type;
+ u32 *expected_btf_id = fn->arg_btf_id[arg];
int err = 0;
if (arg_type == ARG_DONTCARE)
@@ -4132,7 +4131,7 @@ static int check_func_arg(struct
bpf_verifier_env *env, u32 arg,
if (arg_type == ARG_PTR_TO_MAP_VALUE ||
arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE ||
arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) {
- err = resolve_map_arg_type(env, meta, &arg_type);
+ err = resolve_map_arg_type(env, meta, &arg_type, &expected_btf_id);
if (err)
return err;
}
@@ -4143,7 +4142,7 @@ static int check_func_arg(struct
bpf_verifier_env *env, u32 arg,
*/
goto skip_type_check;
- err = check_reg_type(env, arg, arg_type, fn);
+ err = check_reg_type(env, regno, arg_type, expected_btf_id);
if (err)
return err;
--
2.25.1
--
Lorenz Bauer | Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK
www.cloudflare.com
next prev parent reply other threads:[~2020-09-22 9:57 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 7:04 [PATCH v3 bpf-next 00/11] bpf: Enable bpf_skc_to_* sock casting helper to networking prog type Martin KaFai Lau
2020-09-22 7:04 ` [PATCH v3 bpf-next 01/11] bpf: Move the PTR_TO_BTF_ID check to check_reg_type() Martin KaFai Lau
2020-09-22 9:56 ` Lorenz Bauer [this message]
2020-09-22 18:38 ` Martin KaFai Lau
2020-09-23 9:47 ` Lorenz Bauer
2020-09-23 4:45 ` Martin KaFai Lau
2020-09-22 7:04 ` [PATCH v3 bpf-next 02/11] bpf: Enable bpf_skc_to_* sock casting helper to networking prog type Martin KaFai Lau
2020-09-22 9:46 ` Lorenz Bauer
2020-09-22 18:26 ` Martin KaFai Lau
2020-09-23 9:27 ` Lorenz Bauer
2020-09-23 17:05 ` Martin KaFai Lau
2020-09-24 8:38 ` Lorenz Bauer
2020-09-25 1:22 ` Martin KaFai Lau
2020-09-22 7:04 ` [PATCH v3 bpf-next 03/11] bpf: Change bpf_sk_release and bpf_sk_*cgroup_id to accept ARG_PTR_TO_BTF_ID_SOCK_COMMON Martin KaFai Lau
2020-09-22 7:04 ` [PATCH v3 bpf-next 04/11] bpf: Change bpf_sk_storage_*() " Martin KaFai Lau
2020-09-22 9:17 ` Lorenz Bauer
2020-09-22 7:04 ` [PATCH v3 bpf-next 05/11] bpf: Change bpf_tcp_*_syncookie " Martin KaFai Lau
2020-09-22 9:18 ` Lorenz Bauer
2020-09-22 7:04 ` [PATCH v3 bpf-next 06/11] bpf: Change bpf_sk_assign " Martin KaFai Lau
2020-09-22 9:21 ` Lorenz Bauer
2020-09-22 7:04 ` [PATCH v3 bpf-next 07/11] bpf: selftest: Add ref_tracking verifier test for bpf_skc casting Martin KaFai Lau
2020-09-22 7:04 ` [PATCH v3 bpf-next 08/11] bpf: selftest: Move sock_fields test into test_progs Martin KaFai Lau
2020-09-23 21:22 ` Andrii Nakryiko
2020-09-22 7:05 ` [PATCH v3 bpf-next 09/11] bpf: selftest: Adapt sock_fields test to use skel and global variables Martin KaFai Lau
2020-09-22 7:05 ` [PATCH v3 bpf-next 10/11] bpf: selftest: Use network_helpers in the sock_fields test Martin KaFai Lau
2020-09-22 7:05 ` [PATCH v3 bpf-next 11/11] bpf: selftest: Use bpf_skc_to_tcp_sock() " Martin KaFai Lau
2020-09-22 20:16 ` Alexei Starovoitov
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