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Message-ID: <20241119104922.2772571-2-roberto.sassu@huaweicloud.com>
Date: Tue, 19 Nov 2024 11:49:08 +0100
From: Roberto Sassu <roberto.sassu@...weicloud.com>
To: zohar@...ux.ibm.com,
dmitry.kasatkin@...il.com,
eric.snowberg@...cle.com,
corbet@....net,
mcgrof@...nel.org,
petr.pavlu@...e.com,
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jmorris@...ei.org,
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Cc: linux-integrity@...r.kernel.org,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
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Roberto Sassu <roberto.sassu@...wei.com>
Subject: [PATCH v6 01/15] lib: Add TLV parser
From: Roberto Sassu <roberto.sassu@...wei.com>
Add a parser of a generic Type-Length-Value (TLV) format:
+--------------+--+---------+--------+---------+
| field1 (u16) | len1 (u32) | value1 (u8 len1) |
+--------------+------------+------------------+
| ... | ... | ... |
+--------------+------------+------------------+
| fieldN (u16) | lenN (u32) | valueN (u8 lenN) |
+--------------+------------+------------------+
Each adopter can define its own fields. The TLV parser does not need to be
aware of those, but lets the adopter obtain the data and decide how to
continue.
After processing a TLV entry, call the callback function also with the
callback data provided by the adopter. The latter can decide how to
interpret the TLV entry depending on the field ID.
Nesting TLVs is also possible, the callback function can call tlv_parse()
to parse the inner structure.
Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
---
MAINTAINERS | 8 +++
include/linux/tlv_parser.h | 32 ++++++++++++
include/uapi/linux/tlv_parser.h | 41 ++++++++++++++++
lib/Kconfig | 3 ++
lib/Makefile | 2 +
lib/tlv_parser.c | 87 +++++++++++++++++++++++++++++++++
lib/tlv_parser.h | 18 +++++++
7 files changed, 191 insertions(+)
create mode 100644 include/linux/tlv_parser.h
create mode 100644 include/uapi/linux/tlv_parser.h
create mode 100644 lib/tlv_parser.c
create mode 100644 lib/tlv_parser.h
diff --git a/MAINTAINERS b/MAINTAINERS
index a097afd76ded..1f7ffa1c9dbd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -23388,6 +23388,14 @@ W: http://sourceforge.net/projects/tlan/
F: Documentation/networking/device_drivers/ethernet/ti/tlan.rst
F: drivers/net/ethernet/ti/tlan.*
+TLV PARSER
+M: Roberto Sassu <roberto.sassu@...wei.com>
+L: linux-kernel@...r.kernel.org
+S: Maintained
+F: include/linux/tlv_parser.h
+F: include/uapi/linux/tlv_parser.h
+F: lib/tlv_parser.*
+
TMIO/SDHI MMC DRIVER
M: Wolfram Sang <wsa+renesas@...g-engineering.com>
L: linux-mmc@...r.kernel.org
diff --git a/include/linux/tlv_parser.h b/include/linux/tlv_parser.h
new file mode 100644
index 000000000000..0c72742af548
--- /dev/null
+++ b/include/linux/tlv_parser.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@...wei.com>
+ *
+ * Header file of TLV parser.
+ */
+
+#ifndef _LINUX_TLV_PARSER_H
+#define _LINUX_TLV_PARSER_H
+
+#include <uapi/linux/tlv_parser.h>
+
+/**
+ * typedef callback - Callback after parsing TLV entry
+ * @callback_data: Opaque data to supply to the callback function
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_len: Length of @field_data
+ *
+ * This callback is invoked after a TLV entry is parsed.
+ *
+ * Return: Zero on success, a negative value on error.
+ */
+typedef int (*callback)(void *callback_data, __u16 field,
+ const __u8 *field_data, __u32 field_len);
+
+int tlv_parse(callback callback, void *callback_data, const __u8 *data,
+ size_t data_len, const char **fields, __u32 num_fields);
+
+#endif /* _LINUX_TLV_PARSER_H */
diff --git a/include/uapi/linux/tlv_parser.h b/include/uapi/linux/tlv_parser.h
new file mode 100644
index 000000000000..171d0cfd2c4c
--- /dev/null
+++ b/include/uapi/linux/tlv_parser.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@...wei.com>
+ *
+ * Implement the user space interface for the TLV parser.
+ */
+
+#ifndef _UAPI_LINUX_TLV_PARSER_H
+#define _UAPI_LINUX_TLV_PARSER_H
+
+#include <linux/types.h>
+
+/*
+ * TLV format:
+ *
+ * +--------------+--+---------+--------+---------+
+ * | field1 (u16) | len1 (u32) | value1 (u8 len1) |
+ * +--------------+------------+------------------+
+ * | ... | ... | ... |
+ * +--------------+------------+------------------+
+ * | fieldN (u16) | lenN (u32) | valueN (u8 lenN) |
+ * +--------------+------------+------------------+
+ */
+
+/**
+ * struct tlv_entry - Entry of TLV format
+ * @field: Field identifier
+ * @length: Data length
+ * @data: Data
+ *
+ * This structure represents an entry of the TLV format.
+ */
+struct tlv_entry {
+ __u16 field;
+ __u32 length;
+ __u8 data[];
+} __attribute__((packed));
+
+#endif /* _UAPI_LINUX_TLV_PARSER_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index b38849af6f13..9141dcfc1704 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -777,3 +777,6 @@ config POLYNOMIAL
config FIRMWARE_TABLE
bool
+
+config TLV_PARSER
+ bool
diff --git a/lib/Makefile b/lib/Makefile
index 773adf88af41..630de494eab5 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -393,5 +393,7 @@ obj-$(CONFIG_USERCOPY_KUNIT_TEST) += usercopy_kunit.o
obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
obj-$(CONFIG_FIRMWARE_TABLE) += fw_table.o
+obj-$(CONFIG_TLV_PARSER) += tlv_parser.o
+CFLAGS_tlv_parser.o += -I lib
subdir-$(CONFIG_FORTIFY_SOURCE) += test_fortify
diff --git a/lib/tlv_parser.c b/lib/tlv_parser.c
new file mode 100644
index 000000000000..dbbe08018b4d
--- /dev/null
+++ b/lib/tlv_parser.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@...wei.com>
+ *
+ * Implement the TLV parser.
+ */
+
+#define pr_fmt(fmt) "tlv_parser: "fmt
+#include <tlv_parser.h>
+
+/**
+ * tlv_parse - Parse TLV data
+ * @callback: Callback function to call to parse the entries
+ * @callback_data: Opaque data to supply to the callback function
+ * @data: Data to parse
+ * @data_len: Length of @data
+ * @fields: Array of field strings
+ * @num_fields: Number of elements of @fields
+ *
+ * Parse the TLV data format and call the supplied callback function for each
+ * entry, passing also the opaque data pointer.
+ *
+ * The callback function decides how to process data depending on the field.
+ *
+ * Return: Zero on success, a negative value on error.
+ */
+int tlv_parse(callback callback, void *callback_data, const __u8 *data,
+ size_t data_len, const char **fields, __u32 num_fields)
+{
+ const __u8 *data_ptr = data;
+ struct tlv_entry *entry;
+ __u16 parsed_field;
+ __u32 len;
+ int ret;
+
+ if (data_len > U32_MAX) {
+ pr_debug("Data too big, size: %zd\n", data_len);
+ return -E2BIG;
+ }
+
+ while (data_len) {
+ if (data_len < sizeof(*entry))
+ return -EBADMSG;
+
+ entry = (struct tlv_entry *)data_ptr;
+ data_ptr += sizeof(*entry);
+ data_len -= sizeof(*entry);
+
+ parsed_field = __be16_to_cpu(entry->field);
+ if (parsed_field >= num_fields) {
+ pr_debug("Invalid field %u, max: %u\n",
+ parsed_field, num_fields - 1);
+ return -EBADMSG;
+ }
+
+ len = __be32_to_cpu(entry->length);
+
+ if (data_len < len)
+ return -EBADMSG;
+
+ pr_debug("Data: field: %s, len: %u\n", fields[parsed_field],
+ len);
+
+ if (!len)
+ continue;
+
+ ret = callback(callback_data, parsed_field, data_ptr, len);
+ if (ret < 0) {
+ pr_debug("Parsing of field %s failed, ret: %d\n",
+ fields[parsed_field], ret);
+ return ret;
+ }
+
+ data_ptr += len;
+ data_len -= len;
+ }
+
+ if (data_len) {
+ pr_debug("Excess data: %zu bytes\n", data_len);
+ return -EBADMSG;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tlv_parse);
diff --git a/lib/tlv_parser.h b/lib/tlv_parser.h
new file mode 100644
index 000000000000..e663966deac5
--- /dev/null
+++ b/lib/tlv_parser.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@...wei.com>
+ *
+ * Header file of TLV parser.
+ */
+
+#ifndef _LIB_TLV_PARSER_H
+#define _LIB_TLV_PARSER_H
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/limits.h>
+#include <linux/tlv_parser.h>
+
+#endif /* _LIB_TLV_PARSER_H */
--
2.47.0.118.gfd3785337b
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