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 */ 82 static inline void *libbpf_nla_data(const struct nlattr *nla) 83 { 84 return (void *)nla + NLA_HDRLEN; 85 } 86 87 static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla) 88 { 89 return *(uint8_t *)libbpf_nla_data(nla); 90 } 91 92 static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla) 93 { 94 return *(uint32_t *)libbpf_nla_data(nla); 95 } 96 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 */ 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); 118 119 static inline struct nlattr *nla_data(struct nlattr *nla) 120 { 121 return (struct nlattr *)((void *)nla + NLA_HDRLEN); 122 } 123 124 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 } 128 129 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 } 147 148 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 } 157 158 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