From: Ihor Solodrai <ihor.solodrai@linux.dev>
To: bpf@vger.kernel.org
Cc: andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net,
eddyz87@gmail.com, mykolal@fb.com, jose.marchesi@oracle.com
Subject: [PATCH bpf-next v3 5/6] bpf: allow kind_flag for BTF type and decl tags
Date: Thu, 30 Jan 2025 12:12:38 -0800 [thread overview]
Message-ID: <20250130201239.1429648-6-ihor.solodrai@linux.dev> (raw)
In-Reply-To: <20250130201239.1429648-1-ihor.solodrai@linux.dev>
BTF type tags and decl tags now may have info->kflag set to 1,
changing the semantics of the tag.
Change BTF verification to permit BTF that makes use of this feature:
* remove kflag check in btf_decl_tag_check_meta(), as both values
are valid
* allow kflag to be set for BTF_KIND_TYPE_TAG type in
btf_ref_type_check_meta()
Make sure kind_flag is NOT set when checking for specific BTF tags,
such as "kptr", "user" etc.
Modify a selftest checking for kflag in decl_tag accordingly.
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
kernel/bpf/btf.c | 26 +++++++++-----------
tools/testing/selftests/bpf/prog_tests/btf.c | 4 +--
2 files changed, 13 insertions(+), 17 deletions(-)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 9de6acddd479..9433b6467bbe 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -2575,7 +2575,7 @@ static int btf_ref_type_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}
- if (btf_type_kflag(t)) {
+ if (btf_type_kflag(t) && !btf_type_is_type_tag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
@@ -3332,6 +3332,8 @@ static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
u32 off, int sz, struct btf_field_info *info, u32 field_mask)
{
enum btf_field_type type;
+ const char *tag_value;
+ bool is_type_tag;
u32 res_id;
/* Permit modifiers on the pointer itself */
@@ -3341,19 +3343,20 @@ static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
if (!btf_type_is_ptr(t))
return BTF_FIELD_IGNORE;
t = btf_type_by_id(btf, t->type);
-
- if (!btf_type_is_type_tag(t))
+ is_type_tag = btf_type_is_type_tag(t) && !btf_type_kflag(t);
+ if (!is_type_tag)
return BTF_FIELD_IGNORE;
/* Reject extra tags */
if (btf_type_is_type_tag(btf_type_by_id(btf, t->type)))
return -EINVAL;
- if (!strcmp("kptr_untrusted", __btf_name_by_offset(btf, t->name_off)))
+ tag_value = __btf_name_by_offset(btf, t->name_off);
+ if (!strcmp("kptr_untrusted", tag_value))
type = BPF_KPTR_UNREF;
- else if (!strcmp("kptr", __btf_name_by_offset(btf, t->name_off)))
+ else if (!strcmp("kptr", tag_value))
type = BPF_KPTR_REF;
- else if (!strcmp("percpu_kptr", __btf_name_by_offset(btf, t->name_off)))
+ else if (!strcmp("percpu_kptr", tag_value))
type = BPF_KPTR_PERCPU;
- else if (!strcmp("uptr", __btf_name_by_offset(btf, t->name_off)))
+ else if (!strcmp("uptr", tag_value))
type = BPF_UPTR;
else
return -EINVAL;
@@ -4944,11 +4947,6 @@ static s32 btf_decl_tag_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}
- if (btf_type_kflag(t)) {
- btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
- return -EINVAL;
- }
-
component_idx = btf_type_decl_tag(t)->component_idx;
if (component_idx < -1) {
btf_verifier_log_type(env, t, "Invalid component_idx");
@@ -6743,7 +6741,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
info->btf_id = t->type;
t = btf_type_by_id(btf, t->type);
- if (btf_type_is_type_tag(t)) {
+ if (btf_type_is_type_tag(t) && !btf_type_kflag(t)) {
tag_value = __btf_name_by_offset(btf, t->name_off);
if (strcmp(tag_value, "user") == 0)
info->reg_type |= MEM_USER;
@@ -7002,7 +7000,7 @@ static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf,
/* check type tag */
t = btf_type_by_id(btf, mtype->type);
- if (btf_type_is_type_tag(t)) {
+ if (btf_type_is_type_tag(t) && !btf_type_kflag(t)) {
tag_value = __btf_name_by_offset(btf, t->name_off);
/* check __user tag */
if (strcmp(tag_value, "user") == 0)
diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c
index e63d74ce046f..aab9ad88c845 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf.c
@@ -3866,7 +3866,7 @@ static struct btf_raw_test raw_tests[] = {
.err_str = "vlen != 0",
},
{
- .descr = "decl_tag test #8, invalid kflag",
+ .descr = "decl_tag test #8, tag with kflag",
.raw_types = {
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
BTF_VAR_ENC(NAME_TBD, 1, 0), /* [2] */
@@ -3881,8 +3881,6 @@ static struct btf_raw_test raw_tests[] = {
.key_type_id = 1,
.value_type_id = 1,
.max_entries = 1,
- .btf_load_err = true,
- .err_str = "Invalid btf_info kind_flag",
},
{
.descr = "decl_tag test #9, var, invalid component_idx",
--
2.48.1
next prev parent reply other threads:[~2025-01-30 20:12 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-30 20:12 [PATCH bpf-next v3 0/6] BTF: arbitrary __attribute__ encoding Ihor Solodrai
2025-01-30 20:12 ` [PATCH bpf-next v3 1/6] libbpf: introduce kflag for type_tags and decl_tags in BTF Ihor Solodrai
2025-01-30 20:12 ` [PATCH bpf-next v3 2/6] docs/bpf: document the semantics of BTF tags with kind_flag Ihor Solodrai
2025-01-30 20:12 ` [PATCH bpf-next v3 3/6] libbpf: check the kflag of type tags in btf_dump Ihor Solodrai
2025-01-30 20:12 ` [PATCH bpf-next v3 4/6] selftests/bpf: add a btf_dump test for type_tags Ihor Solodrai
2025-01-30 20:12 ` Ihor Solodrai [this message]
2025-01-31 2:55 ` [PATCH bpf-next v3 5/6] bpf: allow kind_flag for BTF type and decl tags Eduard Zingerman
2025-01-31 3:55 ` Ihor Solodrai
2025-01-30 20:12 ` [PATCH bpf-next v3 6/6] selftests/bpf: add a BTF verification test for kflagged type_tag Ihor Solodrai
2025-02-06 1:00 ` [PATCH bpf-next v3 0/6] BTF: arbitrary __attribute__ encoding patchwork-bot+netdevbpf
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