LXR linux/tools/lib/bpf/nlattr.h

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