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  */
24 enum {
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  */
45 struct 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 
56 struct 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  */
libbpf_nla_data(const struct nlattr * nla)82 static inline void *libbpf_nla_data(const struct nlattr *nla)
83 {
84 	return (void *)nla + NLA_HDRLEN;
85 }
86 
libbpf_nla_getattr_u8(const struct nlattr * nla)87 static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla)
88 {
89 	return *(uint8_t *)libbpf_nla_data(nla);
90 }
91 
libbpf_nla_getattr_u32(const struct nlattr * nla)92 static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla)
93 {
94 	return *(uint32_t *)libbpf_nla_data(nla);
95 }
96 
libbpf_nla_getattr_str(const struct nlattr * nla)97 static 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  */
libbpf_nla_len(const struct nlattr * nla)106 static inline int libbpf_nla_len(const struct nlattr *nla)
107 {
108 	return nla->nla_len - NLA_HDRLEN;
109 }
110 
111 int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
112 		     int len, struct libbpf_nla_policy *policy);
113 int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
114 			    struct nlattr *nla,
115 			    struct libbpf_nla_policy *policy);
116 
117 int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh);
118 
nla_data(struct nlattr * nla)119 static inline struct nlattr *nla_data(struct nlattr *nla)
120 {
121 	return (struct nlattr *)((void *)nla + NLA_HDRLEN);
122 }
123 
req_tail(struct libbpf_nla_req * req)124 static 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 
nlattr_add(struct libbpf_nla_req * req,int type,const void * data,int len)129 static 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 
nlattr_begin_nested(struct libbpf_nla_req * req,int type)148 static 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 
nlattr_end_nested(struct libbpf_nla_req * req,struct nlattr * tail)158 static 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 */
165