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Message-Id: <20240718115153.1967859-2-yikai.lin@vivo.com>
Date: Thu, 18 Jul 2024 19:51:43 +0800
From: Lin Yikai <yikai.lin@...o.com>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>,
Eduard Zingerman <eddyz87@...il.com>,
Song Liu <song@...nel.org>,
Yonghong Song <yonghong.song@...ux.dev>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Stanislav Fomichev <sdf@...ichev.me>,
Hao Luo <haoluo@...gle.com>,
Jiri Olsa <jolsa@...nel.org>,
Matt Bobrowski <mattbobrowski@...gle.com>,
Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Mykola Lysenko <mykolal@...com>,
Shuah Khan <shuah@...nel.org>,
Lin Yikai <yikai.lin@...o.com>,
linux-kernel@...r.kernel.org,
bpf@...r.kernel.org,
linux-trace-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org
Cc: opensource.kernel@...o.com
Subject: [PATCH bpf-next v1 1/3] bpf: Add bpf_file_d_path helper
Add the "bpf_file_d_path" helper function
to retrieve the path from a struct file object.
But there is no need to include vmlinux.h
or reference the definition of struct file.
Additionally, update the bpf.h tools uapi header.
Signed-off-by: Lin Yikai <yikai.lin@...o.com>
---
include/uapi/linux/bpf.h | 20 ++++++++++++++++++++
kernel/trace/bpf_trace.c | 34 ++++++++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 20 ++++++++++++++++++++
3 files changed, 74 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 35bcf52dbc65..7e5cec61a877 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5792,6 +5792,25 @@ union bpf_attr {
* 0 on success.
*
* **-ENOENT** if the bpf_local_storage cannot be found.
+ *
+ * long bpf_file_d_path(void *file, char *dst, u32 size)
+ * Description
+ * Return full path for the given *file* object.
+ *
+ * In order to solve issues where certain eBPF programs can not include
+ * the definition of struct file or vmlinux.h
+ * due to their complexity and conflicts on some operating system,
+ * the variable *file* here is declared as type void*
+ * instead of the traditional struct file*.
+ * It will be forcibly converted into type struct file* later.
+ *
+ * If the path is larger than *size*, then only *size*
+ * bytes will be copied to *dst*
+ *
+ * Return
+ * On success, the strictly positive length of the string,
+ * including the trailing NULL character. On error, a negative
+ * value.
*/
#define ___BPF_FUNC_MAPPER(FN, ctx...) \
FN(unspec, 0, ##ctx) \
@@ -6006,6 +6025,7 @@ union bpf_attr {
FN(user_ringbuf_drain, 209, ##ctx) \
FN(cgrp_storage_get, 210, ##ctx) \
FN(cgrp_storage_delete, 211, ##ctx) \
+ FN(file_d_path, 212, ##ctx) \
/* */
/* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index cd098846e251..70fde7f20e97 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1257,6 +1257,38 @@ static const struct bpf_func_proto bpf_get_func_arg_cnt_proto = {
.arg1_type = ARG_PTR_TO_CTX,
};
+BPF_CALL_3(bpf_file_d_path, void *, file, char*, dst, u32, size)
+{
+ long len;
+ struct file copy;
+ char *ptr;
+
+ if (!size)
+ return 0;
+
+ len = copy_from_kernel_nofault(©, (struct file *)file, sizeof(struct file));
+ if (len < 0)
+ return len;
+
+ ptr = d_path(&(copy.f_path), dst, size);
+ if (IS_ERR(ptr)) {
+ len = PTR_ERR(ptr);
+ } else {
+ len = dst + size - ptr;
+ memmove(dst, ptr, len);
+ }
+ return len;
+}
+
+const struct bpf_func_proto bpf_file_d_path_proto = {
+ .func = bpf_file_d_path,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_ANYTHING,
+ .arg2_type = ARG_PTR_TO_MEM,
+ .arg3_type = ARG_CONST_SIZE_OR_ZERO,
+};
+
#ifdef CONFIG_KEYS
__bpf_kfunc_start_defs();
@@ -1629,6 +1661,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_find_vma_proto;
case BPF_FUNC_trace_vprintk:
return bpf_get_trace_vprintk_proto();
+ case BPF_FUNC_file_d_path:
+ return &bpf_file_d_path_proto;
default:
return bpf_base_func_proto(func_id, prog);
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 35bcf52dbc65..7e5cec61a877 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5792,6 +5792,25 @@ union bpf_attr {
* 0 on success.
*
* **-ENOENT** if the bpf_local_storage cannot be found.
+ *
+ * long bpf_file_d_path(void *file, char *dst, u32 size)
+ * Description
+ * Return full path for the given *file* object.
+ *
+ * In order to solve issues where certain eBPF programs can not include
+ * the definition of struct file or vmlinux.h
+ * due to their complexity and conflicts on some operating system,
+ * the variable *file* here is declared as type void*
+ * instead of the traditional struct file*.
+ * It will be forcibly converted into type struct file* later.
+ *
+ * If the path is larger than *size*, then only *size*
+ * bytes will be copied to *dst*
+ *
+ * Return
+ * On success, the strictly positive length of the string,
+ * including the trailing NULL character. On error, a negative
+ * value.
*/
#define ___BPF_FUNC_MAPPER(FN, ctx...) \
FN(unspec, 0, ##ctx) \
@@ -6006,6 +6025,7 @@ union bpf_attr {
FN(user_ringbuf_drain, 209, ##ctx) \
FN(cgrp_storage_get, 210, ##ctx) \
FN(cgrp_storage_delete, 211, ##ctx) \
+ FN(file_d_path, 212, ##ctx) \
/* */
/* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
--
2.34.1
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