lib/netlink.h

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011, 2013, 2015 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef NETLINK_H
  18 #define NETLINK_H 1
  19
  20 /* Netlink message helpers.
  21  *
  22  * Netlink is a datagram-based network protocol primarily for communication
  23  * between user processes and the kernel, and mainly on Linux.  Netlink is
  24  * specified in RFC 3549, "Linux Netlink as an IP Services Protocol".
  25  *
  26  * Netlink is not suitable for use in physical networks of heterogeneous
  27  * machines because host byte order is used throughout.
  28  *
  29  * This header file defines helper functions for working with Netlink messages.
  30  * For Netlink protocol definitions, see netlink-protocol.h.  For
  31  * Linux-specific definitions for Netlink sockets, see netlink-socket.h.
  32  */
  33
  34 #include <sys/types.h>
  35 #include <netinet/in.h>
  36 #include <stdbool.h>
  37 #include <stddef.h>
  38 #include <stdint.h>
  39 #include "netlink-protocol.h"
  40 #include "openvswitch/types.h"
  41
  42 struct ofpbuf;
  43 struct nlattr;
  44
  45 /* Accessing headers and data. */
  46 struct nlmsghdr *nl_msg_nlmsghdr(const struct ofpbuf *);
  47 struct genlmsghdr *nl_msg_genlmsghdr(const struct ofpbuf *);
  48 bool nl_msg_nlmsgerr(const struct ofpbuf *, int *error);
  49 void nl_msg_reserve(struct ofpbuf *, size_t);
  50
  51 /* Appending and prepending headers and raw data. */
  52 void nl_msg_put_nlmsghdr(struct ofpbuf *, size_t expected_payload,
  53                          uint32_t type, uint32_t flags);
  54 void nl_msg_put_genlmsghdr(struct ofpbuf *, size_t expected_payload,
  55                            int family, uint32_t flags,
  56                            uint8_t cmd, uint8_t version);
  57 void nl_msg_put(struct ofpbuf *, const void *, size_t);
  58 void *nl_msg_put_uninit(struct ofpbuf *, size_t);
  59 void nl_msg_push(struct ofpbuf *, const void *, size_t);
  60 void *nl_msg_push_uninit(struct ofpbuf *, size_t);
  61
  62 /* Appending attributes. */
  63 void *nl_msg_put_unspec_uninit(struct ofpbuf *, uint16_t type, size_t);
  64 void *nl_msg_put_unspec_zero(struct ofpbuf *, uint16_t type, size_t);
  65 void nl_msg_put_unspec(struct ofpbuf *, uint16_t type, const void *, size_t);
  66 void nl_msg_put_flag(struct ofpbuf *, uint16_t type);
  67 void nl_msg_put_u8(struct ofpbuf *, uint16_t type, uint8_t value);
  68 void nl_msg_put_u16(struct ofpbuf *, uint16_t type, uint16_t value);
  69 void nl_msg_put_u32(struct ofpbuf *, uint16_t type, uint32_t value);
  70 void nl_msg_put_u64(struct ofpbuf *, uint16_t type, uint64_t value);
  71 void nl_msg_put_u128(struct ofpbuf *, uint16_t type, ovs_u128 value);
  72 void nl_msg_put_be16(struct ofpbuf *, uint16_t type, ovs_be16 value);
  73 void nl_msg_put_be32(struct ofpbuf *, uint16_t type, ovs_be32 value);
  74 void nl_msg_put_be64(struct ofpbuf *, uint16_t type, ovs_be64 value);
  75 void nl_msg_put_be128(struct ofpbuf *, uint16_t type, ovs_be128 value);
  76 void nl_msg_put_in6_addr(struct ofpbuf *msg, uint16_t type,
  77                          const struct in6_addr *value);
  78 void nl_msg_put_odp_port(struct ofpbuf *, uint16_t type, odp_port_t value);
  79 void nl_msg_put_string__(struct ofpbuf *, uint16_t type, const char *value,
  80                          size_t len);
  81 void nl_msg_put_string(struct ofpbuf *, uint16_t type, const char *value);
  82
  83 size_t nl_msg_start_nested(struct ofpbuf *, uint16_t type);
  84 void nl_msg_end_nested(struct ofpbuf *, size_t offset);
  85 void nl_msg_cancel_nested(struct ofpbuf *, size_t offset);
  86 bool nl_msg_end_non_empty_nested(struct ofpbuf *, size_t offset);
  87 void nl_msg_put_nested(struct ofpbuf *, uint16_t type,
  88                        const void *data, size_t size);
  89
  90 /* Prepending attributes. */
  91 void *nl_msg_push_unspec_uninit(struct ofpbuf *, uint16_t type, size_t);
  92 void nl_msg_push_unspec(struct ofpbuf *, uint16_t type, const void *, size_t);
  93 void nl_msg_push_flag(struct ofpbuf *, uint16_t type);
  94 void nl_msg_push_u8(struct ofpbuf *, uint16_t type, uint8_t value);
  95 void nl_msg_push_u16(struct ofpbuf *, uint16_t type, uint16_t value);
  96 void nl_msg_push_u32(struct ofpbuf *, uint16_t type, uint32_t value);
  97 void nl_msg_push_u64(struct ofpbuf *, uint16_t type, uint64_t value);
  98 void nl_msg_push_u128(struct ofpbuf *, uint16_t type, ovs_u128 value);
  99 void nl_msg_push_be16(struct ofpbuf *, uint16_t type, ovs_be16 value);
 100 void nl_msg_push_be32(struct ofpbuf *, uint16_t type, ovs_be32 value);
 101 void nl_msg_push_be64(struct ofpbuf *, uint16_t type, ovs_be64 value);
 102 void nl_msg_push_be128(struct ofpbuf *, uint16_t type, ovs_be128 value);
 103 void nl_msg_push_string(struct ofpbuf *, uint16_t type, const char *value);
 104
 105 /* Separating buffers into individual messages. */
 106 struct nlmsghdr *nl_msg_next(struct ofpbuf *buffer, struct ofpbuf *msg);
 107
 108 /* Sizes of various attribute types, in bytes, including the attribute header
 109  * and padding.
 110  *
 111  * A minimum-size attribute is 4 bytes long: 4 bytes of header, no bytes of
 112  * payload, no padding.
 113  *
 114  * A maximum-size attribute is 65536 bytes long: 4 bytes of header, 65531 bytes
 115  * of payload, 1 byte of padding.  (Thus, NL_ATTR_SIZE() of a maximum length
 116  * attribute payload does not fit in 16 bits.) */
 117 #define NL_ATTR_SIZE(PAYLOAD_SIZE) (NLA_HDRLEN + NLA_ALIGN(PAYLOAD_SIZE))
 118 #define NL_A_U8_SIZE   NL_ATTR_SIZE(sizeof(uint8_t))
 119 #define NL_A_U16_SIZE  NL_ATTR_SIZE(sizeof(uint16_t))
 120 #define NL_A_U32_SIZE  NL_ATTR_SIZE(sizeof(uint32_t))
 121 #define NL_A_U64_SIZE  NL_ATTR_SIZE(sizeof(uint64_t))
 122 #define NL_A_U128_SIZE  NL_ATTR_SIZE(sizeof(ovs_u128))
 123 #define NL_A_BE16_SIZE NL_ATTR_SIZE(sizeof(ovs_be16))
 124 #define NL_A_BE32_SIZE NL_ATTR_SIZE(sizeof(ovs_be32))
 125 #define NL_A_BE64_SIZE NL_ATTR_SIZE(sizeof(ovs_be64))
 126 #define NL_A_BE128_SIZE NL_ATTR_SIZE(sizeof(ovs_be128))
 127 #define NL_A_FLAG_SIZE NL_ATTR_SIZE(0)
 128 #define NL_A_IPV6_SIZE NL_ATTR_SIZE(sizeof(struct in6_addr))
 129
 130 bool nl_attr_oversized(size_t payload_size);
 131 \f
 132 /* Netlink attribute types. */
 133 enum nl_attr_type
 134 {
 135     NL_A_NO_ATTR = 0,
 136     NL_A_UNSPEC,
 137     NL_A_U8,
 138     NL_A_U16,
 139     NL_A_BE16 = NL_A_U16,
 140     NL_A_U32,
 141     NL_A_BE32 = NL_A_U32,
 142     NL_A_U64,
 143     NL_A_BE64 = NL_A_U64,
 144     NL_A_U128,
 145     NL_A_BE128 = NL_A_U128,
 146     NL_A_STRING,
 147     NL_A_FLAG,
 148     NL_A_IPV6,
 149     NL_A_NESTED,
 150     N_NL_ATTR_TYPES
 151 };
 152
 153 /* Netlink attribute iteration. */
 154 static inline struct nlattr *
 155 nl_attr_next(const struct nlattr *nla)
 156 {
 157     return ALIGNED_CAST(struct nlattr *,
 158                         ((uint8_t *) nla + NLA_ALIGN(nla->nla_len)));
 159 }
 160
 161 static inline bool
 162 nl_attr_is_valid(const struct nlattr *nla, size_t maxlen)
 163 {
 164     return (maxlen >= sizeof *nla
 165             && nla->nla_len >= sizeof *nla
 166             && nla->nla_len <= maxlen);
 167 }
 168
 169 static inline size_t
 170 nl_attr_len_pad(const struct nlattr *nla, size_t maxlen)
 171 {
 172     size_t len = NLA_ALIGN(nla->nla_len);
 173
 174     return len <= maxlen ? len : nla->nla_len;
 175 }
 176
 177 /* This macro is careful to check for attributes with bad lengths. */
 178 #define NL_ATTR_FOR_EACH(ITER, LEFT, ATTRS, ATTRS_LEN)                  \
 179     for ((ITER) = (ATTRS), (LEFT) = (ATTRS_LEN);                        \
 180          nl_attr_is_valid(ITER, LEFT);                                  \
 181          (LEFT) -= nl_attr_len_pad(ITER, LEFT), (ITER) = nl_attr_next(ITER))
 182
 183
 184 /* This macro does not check for attributes with bad lengths.  It should only
 185  * be used with messages from trusted sources or with messages that have
 186  * already been validated (e.g. with NL_ATTR_FOR_EACH).  */
 187 #define NL_ATTR_FOR_EACH_UNSAFE(ITER, LEFT, ATTRS, ATTRS_LEN)           \
 188     for ((ITER) = (ATTRS), (LEFT) = (ATTRS_LEN);                        \
 189          (LEFT) > 0;                                                    \
 190          (LEFT) -= nl_attr_len_pad(ITER, LEFT), (ITER) = nl_attr_next(ITER))
 191
 192 /* These variants are convenient for iterating nested attributes. */
 193 #define NL_NESTED_FOR_EACH(ITER, LEFT, A)                               \
 194     NL_ATTR_FOR_EACH(ITER, LEFT, nl_attr_get(A), nl_attr_get_size(A))
 195 #define NL_NESTED_FOR_EACH_UNSAFE(ITER, LEFT, A)                        \
 196     NL_ATTR_FOR_EACH_UNSAFE(ITER, LEFT, nl_attr_get(A), nl_attr_get_size(A))
 197
 198 /* Netlink attribute parsing. */
 199 int nl_attr_type(const struct nlattr *);
 200 const void *nl_attr_get(const struct nlattr *);
 201 size_t nl_attr_get_size(const struct nlattr *);
 202 const void *nl_attr_get_unspec(const struct nlattr *, size_t size);
 203 bool nl_attr_get_flag(const struct nlattr *);
 204 uint8_t nl_attr_get_u8(const struct nlattr *);
 205 uint16_t nl_attr_get_u16(const struct nlattr *);
 206 uint32_t nl_attr_get_u32(const struct nlattr *);
 207 uint64_t nl_attr_get_u64(const struct nlattr *);
 208 ovs_u128 nl_attr_get_u128(const struct nlattr *);
 209 ovs_be16 nl_attr_get_be16(const struct nlattr *);
 210 ovs_be32 nl_attr_get_be32(const struct nlattr *);
 211 ovs_be64 nl_attr_get_be64(const struct nlattr *);
 212 ovs_be128 nl_attr_get_be128(const struct nlattr *);
 213 struct in6_addr nl_attr_get_in6_addr(const struct nlattr *nla);
 214 odp_port_t nl_attr_get_odp_port(const struct nlattr *);
 215 const char *nl_attr_get_string(const struct nlattr *);
 216 void nl_attr_get_nested(const struct nlattr *, struct ofpbuf *);
 217
 218 /* Netlink attribute policy.
 219  *
 220  * Specifies how to parse a single attribute from a Netlink message payload.
 221  */
 222 struct nl_policy
 223 {
 224     enum nl_attr_type type;
 225     size_t min_len, max_len;
 226     bool optional;
 227 };
 228
 229 #define NL_POLICY_FOR(TYPE) \
 230     .type = NL_A_UNSPEC, .min_len = sizeof(TYPE), .max_len = sizeof(TYPE)
 231
 232 bool nl_attr_validate(const struct nlattr *, const struct nl_policy *);
 233
 234 bool nl_policy_parse(const struct ofpbuf *, size_t offset,
 235                      const struct nl_policy[],
 236                      struct nlattr *[], size_t n_attrs);
 237 bool nl_parse_nested(const struct nlattr *, const struct nl_policy[],
 238                      struct nlattr *[], size_t n_attrs);
 239
 240 const struct nlattr *nl_attr_find(const struct ofpbuf *, size_t hdr_len,
 241                                   uint16_t type);
 242 const struct nlattr *nl_attr_find_nested(const struct nlattr *, uint16_t type);
 243 const struct nlattr *nl_attr_find__(const struct nlattr *attrs, size_t size,
 244                                     uint16_t type);
 245
 246 #endif /* netlink.h */