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