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 */
25 enum {
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 */
46 struct 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
57 struct 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 */
libbpf_nla_data(const struct nlattr * nla)84 static inline void *libbpf_nla_data(const struct nlattr *nla)
85 {
86 return (void *)nla + NLA_HDRLEN;
87 }
88
libbpf_nla_getattr_u8(const struct nlattr * nla)89 static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla)
90 {
91 return *(uint8_t *)libbpf_nla_data(nla);
92 }
93
libbpf_nla_getattr_u16(const struct nlattr * nla)94 static inline uint16_t libbpf_nla_getattr_u16(const struct nlattr *nla)
95 {
96 return *(uint16_t *)libbpf_nla_data(nla);
97 }
98
libbpf_nla_getattr_u32(const struct nlattr * nla)99 static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla)
100 {
101 return *(uint32_t *)libbpf_nla_data(nla);
102 }
103
libbpf_nla_getattr_u64(const struct nlattr * nla)104 static inline uint64_t libbpf_nla_getattr_u64(const struct nlattr *nla)
105 {
106 return *(uint64_t *)libbpf_nla_data(nla);
107 }
108
libbpf_nla_getattr_str(const struct nlattr * nla)109 static 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 */
libbpf_nla_len(const struct nlattr * nla)118 static inline int libbpf_nla_len(const struct nlattr *nla)
119 {
120 return nla->nla_len - NLA_HDRLEN;
121 }
122
123 int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
124 int len, struct libbpf_nla_policy *policy);
125 int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
126 struct nlattr *nla,
127 struct libbpf_nla_policy *policy);
128
129 int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh);
130
nla_data(struct nlattr * nla)131 static inline struct nlattr *nla_data(struct nlattr *nla)
132 {
133 return (struct nlattr *)((void *)nla + NLA_HDRLEN);
134 }
135
req_tail(struct libbpf_nla_req * req)136 static 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
nlattr_add(struct libbpf_nla_req * req,int type,const void * data,int len)141 static 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
nlattr_begin_nested(struct libbpf_nla_req * req,int type)160 static 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
nlattr_end_nested(struct libbpf_nla_req * req,struct nlattr * tail)170 static 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