From: Song Liu <song@kernel.org>
To: bpf@vger.kernel.org, fsverity@lists.linux.dev
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
martin.lau@kernel.org, kernel-team@meta.com, ebiggers@kernel.org,
tytso@mit.edu, roberto.sassu@huaweicloud.com,
Song Liu <song@kernel.org>
Subject: [PATCH v2 bpf-next 3/9] bpf: Introduce KF_ARG_PTR_TO_CONST_STR
Date: Sun, 22 Oct 2023 23:13:48 -0700 [thread overview]
Message-ID: <20231023061354.941552-4-song@kernel.org> (raw)
In-Reply-To: <20231023061354.941552-1-song@kernel.org>
KF_ARG_PTR_TO_CONST_STR specifies kfunc args that point to const strings.
This is similar to ARG_PTR_TO_CONST_STR for helpers.
Signed-off-by: Song Liu <song@kernel.org>
---
Documentation/bpf/kfuncs.rst | 24 ++++++++++++++++++++++++
kernel/bpf/verifier.c | 19 +++++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst
index 0d2647fb358d..e696aca08b3a 100644
--- a/Documentation/bpf/kfuncs.rst
+++ b/Documentation/bpf/kfuncs.rst
@@ -137,6 +137,30 @@ Either way, the returned buffer is either NULL, or of size buffer_szk. Without t
annotation, the verifier will reject the program if a null pointer is passed in with
a nonzero size.
+2.2.5 __const_str Annotation
+----------------------------
+This annotation is used to indicate that the argument is a constant string.
+
+An example is given below::
+
+ __bpf_kfunc bpf_get_file_xattr(..., const char *name__const_str, ...)
+ {
+ ...
+ }
+
+In this case, ``bpf_get_file_xattr()`` can be called as::
+
+ bpf_get_file_xattr(..., "xattr_name", ...);
+
+Or::
+
+ const char name[] = "xattr_name"; /* This need to be global */
+ int BPF_PROG(...)
+ {
+ ...
+ bpf_get_file_xattr(..., name, ...);
+ ...
+ }
.. _BPF_kfunc_nodef:
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0abfb3b2c05c..92685e0d7640 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10318,6 +10318,11 @@ static bool is_kfunc_arg_refcounted_kptr(const struct btf *btf, const struct btf
return __kfunc_param_match_suffix(btf, arg, "__refcounted_kptr");
}
+static bool is_kfunc_arg_const_str(const struct btf *btf, const struct btf_param *arg)
+{
+ return __kfunc_param_match_suffix(btf, arg, "__const_str");
+}
+
static bool is_kfunc_arg_scalar_with_name(const struct btf *btf,
const struct btf_param *arg,
const char *name)
@@ -10460,6 +10465,7 @@ enum kfunc_ptr_arg_type {
KF_ARG_PTR_TO_CALLBACK,
KF_ARG_PTR_TO_RB_ROOT,
KF_ARG_PTR_TO_RB_NODE,
+ KF_ARG_PTR_TO_CONST_STR,
};
enum special_kfunc_type {
@@ -10601,6 +10607,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
if (is_kfunc_arg_rbtree_node(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_RB_NODE;
+ if (is_kfunc_arg_const_str(meta->btf, &args[argno]))
+ return KF_ARG_PTR_TO_CONST_STR;
+
if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) {
if (!btf_type_is_struct(ref_t)) {
verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n",
@@ -11205,6 +11214,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
case KF_ARG_PTR_TO_MEM_SIZE:
case KF_ARG_PTR_TO_CALLBACK:
case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
+ case KF_ARG_PTR_TO_CONST_STR:
/* Trusted by default */
break;
default:
@@ -11470,6 +11480,15 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
meta->arg_btf = reg->btf;
meta->arg_btf_id = reg->btf_id;
break;
+ case KF_ARG_PTR_TO_CONST_STR:
+ if (reg->type != PTR_TO_MAP_VALUE) {
+ verbose(env, "arg#%d doesn't point to a const string\n", i);
+ return -EINVAL;
+ }
+ ret = check_reg_const_str(env, reg, regno);
+ if (ret)
+ return ret;
+ break;
}
}
--
2.34.1
next prev parent reply other threads:[~2023-10-23 6:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-23 6:13 [PATCH v2 bpf-next 0/9] bpf: File verification with LSM and fsverity Song Liu
2023-10-23 6:13 ` [PATCH v2 bpf-next 1/9] bpf: Expose bpf_dynptr_slice* kfuncs for in kernel use Song Liu
2023-10-23 6:13 ` [PATCH v2 bpf-next 2/9] bpf: Factor out helper check_reg_const_str() Song Liu
2023-10-23 6:13 ` Song Liu [this message]
2023-10-23 6:13 ` [PATCH v2 bpf-next 4/9] bpf: Add kfunc bpf_get_file_xattr Song Liu
2023-11-02 1:27 ` KP Singh
2023-11-02 6:43 ` Song Liu
2023-10-23 6:13 ` [PATCH v2 bpf-next 5/9] bpf, fsverity: Add kfunc bpf_get_fsverity_digest Song Liu
2023-10-23 6:13 ` [PATCH v2 bpf-next 6/9] Documentation/bpf: Add documentation for filesystem kfuncs Song Liu
2023-10-23 6:13 ` [PATCH v2 bpf-next 7/9] selftests/bpf: Sort config in alphabetic order Song Liu
2023-10-23 6:13 ` [PATCH v2 bpf-next 8/9] selftests/bpf: Add tests for filesystem kfuncs Song Liu
2023-10-23 6:13 ` [PATCH v2 bpf-next 9/9] selftests/bpf: Add test that use fsverity and xattr to sign a file Song Liu
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