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#include <linux/genetlink.h>
18
19/* avoid multiple definition of netlink features */
20#define __LINUX_NETLINK_H
21
22/**
23 * Standard attribute types to specify validation policy
24 */
25enum {
26	LIBBPF_NLA_UNSPEC,	/**< Unspecified type, binary data chunk */
27	LIBBPF_NLA_U8,		/**< 8 bit integer */
28	LIBBPF_NLA_U16,		/**< 16 bit integer */
29	LIBBPF_NLA_U32,		/**< 32 bit integer */
30	LIBBPF_NLA_U64,		/**< 64 bit integer */
31	LIBBPF_NLA_STRING,	/**< NUL terminated character string */
32	LIBBPF_NLA_FLAG,	/**< Flag */
33	LIBBPF_NLA_MSECS,	/**< Micro seconds (64bit) */
34	LIBBPF_NLA_NESTED,	/**< Nested attributes */
35	__LIBBPF_NLA_TYPE_MAX,
36};
37
38#define LIBBPF_NLA_TYPE_MAX (__LIBBPF_NLA_TYPE_MAX - 1)
39
40/**
41 * @ingroup attr
42 * Attribute validation policy.
43 *
44 * See section @core_doc{core_attr_parse,Attribute Parsing} for more details.
45 */
46struct libbpf_nla_policy {
47	/** Type of attribute or LIBBPF_NLA_UNSPEC */
48	uint16_t	type;
49
50	/** Minimal length of payload required */
51	uint16_t	minlen;
52
53	/** Maximal length of payload allowed */
54	uint16_t	maxlen;
55};
56
57struct libbpf_nla_req {
58	struct nlmsghdr nh;
59	union {
60		struct ifinfomsg ifinfo;
61		struct tcmsg tc;
62		struct genlmsghdr gnl;
63	};
64	char buf[128];
65};
66
67/**
68 * @ingroup attr
69 * Iterate over a stream of attributes
70 * @arg pos	loop counter, set to current attribute
71 * @arg head	head of attribute stream
72 * @arg len	length of attribute stream
73 * @arg rem	initialized to len, holds bytes currently remaining in stream
74 */
75#define libbpf_nla_for_each_attr(pos, head, len, rem) \
76	for (pos = head, rem = len; \
77	     nla_ok(pos, rem); \
78	     pos = nla_next(pos, &(rem)))
79
80/**
81 * libbpf_nla_data - head of payload
82 * @nla: netlink attribute
83 */
84static inline void *libbpf_nla_data(const struct nlattr *nla)
85{
86	return (void *)nla + NLA_HDRLEN;
87}
88
89static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla)
90{
91	return *(uint8_t *)libbpf_nla_data(nla);
92}
93
94static inline uint16_t libbpf_nla_getattr_u16(const struct nlattr *nla)
95{
96	return *(uint16_t *)libbpf_nla_data(nla);
97}
98
99static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla)
100{
101	return *(uint32_t *)libbpf_nla_data(nla);
102}
103
104static inline uint64_t libbpf_nla_getattr_u64(const struct nlattr *nla)
105{
106	return *(uint64_t *)libbpf_nla_data(nla);
107}
108
109static inline const char *libbpf_nla_getattr_str(const struct nlattr *nla)
110{
111	return (const char *)libbpf_nla_data(nla);
112}
113
114/**
115 * libbpf_nla_len - length of payload
116 * @nla: netlink attribute
117 */
118static inline int libbpf_nla_len(const struct nlattr *nla)
119{
120	return nla->nla_len - NLA_HDRLEN;
121}
122
123int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
124		     int len, struct libbpf_nla_policy *policy);
125int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
126			    struct nlattr *nla,
127			    struct libbpf_nla_policy *policy);
128
129int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh);
130
131static inline struct nlattr *nla_data(struct nlattr *nla)
132{
133	return (struct nlattr *)((void *)nla + NLA_HDRLEN);
134}
135
136static inline struct nlattr *req_tail(struct libbpf_nla_req *req)
137{
138	return (struct nlattr *)((void *)req + NLMSG_ALIGN(req->nh.nlmsg_len));
139}
140
141static inline int nlattr_add(struct libbpf_nla_req *req, int type,
142			     const void *data, int len)
143{
144	struct nlattr *nla;
145
146	if (NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(NLA_HDRLEN + len) > sizeof(*req))
147		return -EMSGSIZE;
148	if (!!data != !!len)
149		return -EINVAL;
150
151	nla = req_tail(req);
152	nla->nla_type = type;
153	nla->nla_len = NLA_HDRLEN + len;
154	if (data)
155		memcpy(nla_data(nla), data, len);
156	req->nh.nlmsg_len = NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(nla->nla_len);
157	return 0;
158}
159
160static inline struct nlattr *nlattr_begin_nested(struct libbpf_nla_req *req, int type)
161{
162	struct nlattr *tail;
163
164	tail = req_tail(req);
165	if (nlattr_add(req, type | NLA_F_NESTED, NULL, 0))
166		return NULL;
167	return tail;
168}
169
170static inline void nlattr_end_nested(struct libbpf_nla_req *req,
171				     struct nlattr *tail)
172{
173	tail->nla_len = (void *)req_tail(req) - (void *)tail;
174}
175
176#endif /* __LIBBPF_NLATTR_H */
177