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 */ 84 static inline void *libbpf_nla_data(const struct nlattr *nla) 85 { 86 return (void *)nla + NLA_HDRLEN; 87 } 88 89 static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla) 90 { 91 return *(uint8_t *)libbpf_nla_data(nla); 92 } 93 94 static inline uint16_t libbpf_nla_getattr_u16(const struct nlattr *nla) 95 { 96 return *(uint16_t *)libbpf_nla_data(nla); 97 } 98 99 static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla) 100 { 101 return *(uint32_t *)libbpf_nla_data(nla); 102 } 103 104 static inline uint64_t libbpf_nla_getattr_u64(const struct nlattr *nla) 105 { 106 return *(uint64_t *)libbpf_nla_data(nla); 107 } 108 109 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 */ 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); 130 131 static inline struct nlattr *nla_data(struct nlattr *nla) 132 { 133 return (struct nlattr *)((void *)nla + NLA_HDRLEN); 134 } 135 136 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 } 140 141 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 } 159 160 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 } 169 170 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