1/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
  2
  3/*
  4 * NETLINK      Netlink attributes
  5 *
  6 * Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
  7 */
  8
  9#ifndef __LIBBPF_NLATTR_H
 10#define __LIBBPF_NLATTR_H
 11
 12#include <stdint.h>
 13#include <string.h>
 14#include <errno.h>
 15#include <linux/netlink.h>
 16#include <linux/rtnetlink.h>
 17
 18/* avoid multiple definition of netlink features */
 19#define __LINUX_NETLINK_H
 20
 21/**
 22 * Standard attribute types to specify validation policy
 23 */
 24enum {
 25	LIBBPF_NLA_UNSPEC,	/**< Unspecified type, binary data chunk */
 26	LIBBPF_NLA_U8,		/**< 8 bit integer */
 27	LIBBPF_NLA_U16,		/**< 16 bit integer */
 28	LIBBPF_NLA_U32,		/**< 32 bit integer */
 29	LIBBPF_NLA_U64,		/**< 64 bit integer */
 30	LIBBPF_NLA_STRING,	/**< NUL terminated character string */
 31	LIBBPF_NLA_FLAG,	/**< Flag */
 32	LIBBPF_NLA_MSECS,	/**< Micro seconds (64bit) */
 33	LIBBPF_NLA_NESTED,	/**< Nested attributes */
 34	__LIBBPF_NLA_TYPE_MAX,
 35};
 36
 37#define LIBBPF_NLA_TYPE_MAX (__LIBBPF_NLA_TYPE_MAX - 1)
 38
 39/**
 40 * @ingroup attr
 41 * Attribute validation policy.
 42 *
 43 * See section @core_doc{core_attr_parse,Attribute Parsing} for more details.
 44 */
 45struct libbpf_nla_policy {
 46	/** Type of attribute or LIBBPF_NLA_UNSPEC */
 47	uint16_t	type;
 48
 49	/** Minimal length of payload required */
 50	uint16_t	minlen;
 51
 52	/** Maximal length of payload allowed */
 53	uint16_t	maxlen;
 54};
 55
 56struct libbpf_nla_req {
 57	struct nlmsghdr nh;
 58	union {
 59		struct ifinfomsg ifinfo;
 60		struct tcmsg tc;
 61	};
 62	char buf[128];
 63};
 64
 65/**
 66 * @ingroup attr
 67 * Iterate over a stream of attributes
 68 * @arg pos	loop counter, set to current attribute
 69 * @arg head	head of attribute stream
 70 * @arg len	length of attribute stream
 71 * @arg rem	initialized to len, holds bytes currently remaining in stream
 72 */
 73#define libbpf_nla_for_each_attr(pos, head, len, rem) \
 74	for (pos = head, rem = len; \
 75	     nla_ok(pos, rem); \
 76	     pos = nla_next(pos, &(rem)))
 77
 78/**
 79 * libbpf_nla_data - head of payload
 80 * @nla: netlink attribute
 81 */
 82static inline void *libbpf_nla_data(const struct nlattr *nla)
 83{
 84	return (void *)nla + NLA_HDRLEN;
 85}
 86
 87static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla)
 88{
 89	return *(uint8_t *)libbpf_nla_data(nla);
 90}
 91
 92static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla)
 93{
 94	return *(uint32_t *)libbpf_nla_data(nla);
 95}
 96
 97static inline const char *libbpf_nla_getattr_str(const struct nlattr *nla)
 98{
 99	return (const char *)libbpf_nla_data(nla);
100}
101
102/**
103 * libbpf_nla_len - length of payload
104 * @nla: netlink attribute
105 */
106static inline int libbpf_nla_len(const struct nlattr *nla)
107{
108	return nla->nla_len - NLA_HDRLEN;
109}
110
111int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
112		     int len, struct libbpf_nla_policy *policy);
113int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
114			    struct nlattr *nla,
115			    struct libbpf_nla_policy *policy);
116
117int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh);
118
119static inline struct nlattr *nla_data(struct nlattr *nla)
120{
121	return (struct nlattr *)((void *)nla + NLA_HDRLEN);
122}
123
124static inline struct nlattr *req_tail(struct libbpf_nla_req *req)
125{
126	return (struct nlattr *)((void *)req + NLMSG_ALIGN(req->nh.nlmsg_len));
127}
128
129static inline int nlattr_add(struct libbpf_nla_req *req, int type,
130			     const void *data, int len)
131{
132	struct nlattr *nla;
133
134	if (NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(NLA_HDRLEN + len) > sizeof(*req))
135		return -EMSGSIZE;
136	if (!!data != !!len)
137		return -EINVAL;
138
139	nla = req_tail(req);
140	nla->nla_type = type;
141	nla->nla_len = NLA_HDRLEN + len;
142	if (data)
143		memcpy(nla_data(nla), data, len);
144	req->nh.nlmsg_len = NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(nla->nla_len);
145	return 0;
146}
147
148static inline struct nlattr *nlattr_begin_nested(struct libbpf_nla_req *req, int type)
149{
150	struct nlattr *tail;
151
152	tail = req_tail(req);
153	if (nlattr_add(req, type | NLA_F_NESTED, NULL, 0))
154		return NULL;
155	return tail;
156}
157
158static inline void nlattr_end_nested(struct libbpf_nla_req *req,
159				     struct nlattr *tail)
160{
161	tail->nla_len = (void *)req_tail(req) - (void *)tail;
162}
163
164#endif /* __LIBBPF_NLATTR_H */