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| 1 | #ifndef __NET_NSH_H |
|---|---|
| 2 | #define __NET_NSH_H 1 |
| 3 | |
| 4 | #include <linux/skbuff.h> |
| 5 | |
| 6 | /* |
| 7 | * Network Service Header: |
| 8 | * 0 1 2 3 |
| 9 | * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
| 10 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 11 | * |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol | |
| 12 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 13 | * | Service Path Identifier (SPI) | Service Index | |
| 14 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 15 | * | | |
| 16 | * ~ Mandatory/Optional Context Headers ~ |
| 17 | * | | |
| 18 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 19 | * |
| 20 | * Version: The version field is used to ensure backward compatibility |
| 21 | * going forward with future NSH specification updates. It MUST be set |
| 22 | * to 0x0 by the sender, in this first revision of NSH. Given the |
| 23 | * widespread implementation of existing hardware that uses the first |
| 24 | * nibble after an MPLS label stack for ECMP decision processing, this |
| 25 | * document reserves version 01b and this value MUST NOT be used in |
| 26 | * future versions of the protocol. Please see [RFC7325] for further |
| 27 | * discussion of MPLS-related forwarding requirements. |
| 28 | * |
| 29 | * O bit: Setting this bit indicates an Operations, Administration, and |
| 30 | * Maintenance (OAM) packet. The actual format and processing of SFC |
| 31 | * OAM packets is outside the scope of this specification (see for |
| 32 | * example [I-D.ietf-sfc-oam-framework] for one approach). |
| 33 | * |
| 34 | * The O bit MUST be set for OAM packets and MUST NOT be set for non-OAM |
| 35 | * packets. The O bit MUST NOT be modified along the SFP. |
| 36 | * |
| 37 | * SF/SFF/SFC Proxy/Classifier implementations that do not support SFC |
| 38 | * OAM procedures SHOULD discard packets with O bit set, but MAY support |
| 39 | * a configurable parameter to enable forwarding received SFC OAM |
| 40 | * packets unmodified to the next element in the chain. Forwarding OAM |
| 41 | * packets unmodified by SFC elements that do not support SFC OAM |
| 42 | * procedures may be acceptable for a subset of OAM functions, but can |
| 43 | * result in unexpected outcomes for others, thus it is recommended to |
| 44 | * analyze the impact of forwarding an OAM packet for all OAM functions |
| 45 | * prior to enabling this behavior. The configurable parameter MUST be |
| 46 | * disabled by default. |
| 47 | * |
| 48 | * TTL: Indicates the maximum SFF hops for an SFP. This field is used |
| 49 | * for service plane loop detection. The initial TTL value SHOULD be |
| 50 | * configurable via the control plane; the configured initial value can |
| 51 | * be specific to one or more SFPs. If no initial value is explicitly |
| 52 | * provided, the default initial TTL value of 63 MUST be used. Each SFF |
| 53 | * involved in forwarding an NSH packet MUST decrement the TTL value by |
| 54 | * 1 prior to NSH forwarding lookup. Decrementing by 1 from an incoming |
| 55 | * value of 0 shall result in a TTL value of 63. The packet MUST NOT be |
| 56 | * forwarded if TTL is, after decrement, 0. |
| 57 | * |
| 58 | * All other flag fields, marked U, are unassigned and available for |
| 59 | * future use, see Section 11.2.1. Unassigned bits MUST be set to zero |
| 60 | * upon origination, and MUST be ignored and preserved unmodified by |
| 61 | * other NSH supporting elements. Elements which do not understand the |
| 62 | * meaning of any of these bits MUST NOT modify their actions based on |
| 63 | * those unknown bits. |
| 64 | * |
| 65 | * Length: The total length, in 4-byte words, of NSH including the Base |
| 66 | * Header, the Service Path Header, the Fixed Length Context Header or |
| 67 | * Variable Length Context Header(s). The length MUST be 0x6 for MD |
| 68 | * Type equal to 0x1, and MUST be 0x2 or greater for MD Type equal to |
| 69 | * 0x2. The length of the NSH header MUST be an integer multiple of 4 |
| 70 | * bytes, thus variable length metadata is always padded out to a |
| 71 | * multiple of 4 bytes. |
| 72 | * |
| 73 | * MD Type: Indicates the format of NSH beyond the mandatory Base Header |
| 74 | * and the Service Path Header. MD Type defines the format of the |
| 75 | * metadata being carried. |
| 76 | * |
| 77 | * 0x0 - This is a reserved value. Implementations SHOULD silently |
| 78 | * discard packets with MD Type 0x0. |
| 79 | * |
| 80 | * 0x1 - This indicates that the format of the header includes a fixed |
| 81 | * length Context Header (see Figure 4 below). |
| 82 | * |
| 83 | * 0x2 - This does not mandate any headers beyond the Base Header and |
| 84 | * Service Path Header, but may contain optional variable length Context |
| 85 | * Header(s). The semantics of the variable length Context Header(s) |
| 86 | * are not defined in this document. The format of the optional |
| 87 | * variable length Context Headers is provided in Section 2.5.1. |
| 88 | * |
| 89 | * 0xF - This value is reserved for experimentation and testing, as per |
| 90 | * [RFC3692]. Implementations not explicitly configured to be part of |
| 91 | * an experiment SHOULD silently discard packets with MD Type 0xF. |
| 92 | * |
| 93 | * Next Protocol: indicates the protocol type of the encapsulated data. |
| 94 | * NSH does not alter the inner payload, and the semantics on the inner |
| 95 | * protocol remain unchanged due to NSH service function chaining. |
| 96 | * Please see the IANA Considerations section below, Section 11.2.5. |
| 97 | * |
| 98 | * This document defines the following Next Protocol values: |
| 99 | * |
| 100 | * 0x1: IPv4 |
| 101 | * 0x2: IPv6 |
| 102 | * 0x3: Ethernet |
| 103 | * 0x4: NSH |
| 104 | * 0x5: MPLS |
| 105 | * 0xFE: Experiment 1 |
| 106 | * 0xFF: Experiment 2 |
| 107 | * |
| 108 | * Packets with Next Protocol values not supported SHOULD be silently |
| 109 | * dropped by default, although an implementation MAY provide a |
| 110 | * configuration parameter to forward them. Additionally, an |
| 111 | * implementation not explicitly configured for a specific experiment |
| 112 | * [RFC3692] SHOULD silently drop packets with Next Protocol values 0xFE |
| 113 | * and 0xFF. |
| 114 | * |
| 115 | * Service Path Identifier (SPI): Identifies a service path. |
| 116 | * Participating nodes MUST use this identifier for Service Function |
| 117 | * Path selection. The initial classifier MUST set the appropriate SPI |
| 118 | * for a given classification result. |
| 119 | * |
| 120 | * Service Index (SI): Provides location within the SFP. The initial |
| 121 | * classifier for a given SFP SHOULD set the SI to 255, however the |
| 122 | * control plane MAY configure the initial value of SI as appropriate |
| 123 | * (i.e., taking into account the length of the service function path). |
| 124 | * The Service Index MUST be decremented by a value of 1 by Service |
| 125 | * Functions or by SFC Proxy nodes after performing required services |
| 126 | * and the new decremented SI value MUST be used in the egress packet's |
| 127 | * NSH. The initial Classifier MUST send the packet to the first SFF in |
| 128 | * the identified SFP for forwarding along an SFP. If re-classification |
| 129 | * occurs, and that re-classification results in a new SPI, the |
| 130 | * (re)classifier is, in effect, the initial classifier for the |
| 131 | * resultant SPI. |
| 132 | * |
| 133 | * The SI is used in conjunction the with Service Path Identifier for |
| 134 | * Service Function Path Selection and for determining the next SFF/SF |
| 135 | * in the path. The SI is also valuable when troubleshooting or |
| 136 | * reporting service paths. Additionally, while the TTL field is the |
| 137 | * main mechanism for service plane loop detection, the SI can also be |
| 138 | * used for detecting service plane loops. |
| 139 | * |
| 140 | * When the Base Header specifies MD Type = 0x1, a Fixed Length Context |
| 141 | * Header (16-bytes) MUST be present immediately following the Service |
| 142 | * Path Header. The value of a Fixed Length Context |
| 143 | * Header that carries no metadata MUST be set to zero. |
| 144 | * |
| 145 | * When the base header specifies MD Type = 0x2, zero or more Variable |
| 146 | * Length Context Headers MAY be added, immediately following the |
| 147 | * Service Path Header (see Figure 5). Therefore, Length = 0x2, |
| 148 | * indicates that only the Base Header followed by the Service Path |
| 149 | * Header are present. The optional Variable Length Context Headers |
| 150 | * MUST be of an integer number of 4-bytes. The base header Length |
| 151 | * field MUST be used to determine the offset to locate the original |
| 152 | * packet or frame for SFC nodes that require access to that |
| 153 | * information. |
| 154 | * |
| 155 | * The format of the optional variable length Context Headers |
| 156 | * |
| 157 | * 0 1 2 3 |
| 158 | * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
| 159 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 160 | * | Metadata Class | Type |U| Length | |
| 161 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 162 | * | Variable Metadata | |
| 163 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 164 | * |
| 165 | * Metadata Class (MD Class): Defines the scope of the 'Type' field to |
| 166 | * provide a hierarchical namespace. The IANA Considerations |
| 167 | * Section 11.2.4 defines how the MD Class values can be allocated to |
| 168 | * standards bodies, vendors, and others. |
| 169 | * |
| 170 | * Type: Indicates the explicit type of metadata being carried. The |
| 171 | * definition of the Type is the responsibility of the MD Class owner. |
| 172 | * |
| 173 | * Unassigned bit: One unassigned bit is available for future use. This |
| 174 | * bit MUST NOT be set, and MUST be ignored on receipt. |
| 175 | * |
| 176 | * Length: Indicates the length of the variable metadata, in bytes. In |
| 177 | * case the metadata length is not an integer number of 4-byte words, |
| 178 | * the sender MUST add pad bytes immediately following the last metadata |
| 179 | * byte to extend the metadata to an integer number of 4-byte words. |
| 180 | * The receiver MUST round up the length field to the nearest 4-byte |
| 181 | * word boundary, to locate and process the next field in the packet. |
| 182 | * The receiver MUST access only those bytes in the metadata indicated |
| 183 | * by the length field (i.e., actual number of bytes) and MUST ignore |
| 184 | * the remaining bytes up to the nearest 4-byte word boundary. The |
| 185 | * Length may be 0 or greater. |
| 186 | * |
| 187 | * A value of 0 denotes a Context Header without a Variable Metadata |
| 188 | * field. |
| 189 | * |
| 190 | * [0] https://datatracker.ietf.org/doc/draft-ietf-sfc-nsh/ |
| 191 | */ |
| 192 | |
| 193 | /** |
| 194 | * struct nsh_md1_ctx - Keeps track of NSH context data |
| 195 | * @context: NSH Contexts. |
| 196 | */ |
| 197 | struct nsh_md1_ctx { |
| 198 | __be32 context[4]; |
| 199 | }; |
| 200 | |
| 201 | struct nsh_md2_tlv { |
| 202 | __be16 md_class; |
| 203 | u8 type; |
| 204 | u8 length; |
| 205 | u8 md_value[]; |
| 206 | }; |
| 207 | |
| 208 | struct nshhdr { |
| 209 | __be16 ver_flags_ttl_len; |
| 210 | u8 mdtype; |
| 211 | u8 np; |
| 212 | __be32 path_hdr; |
| 213 | union { |
| 214 | struct nsh_md1_ctx md1; |
| 215 | struct nsh_md2_tlv md2; |
| 216 | }; |
| 217 | }; |
| 218 | |
| 219 | /* Masking NSH header fields. */ |
| 220 | #define NSH_VER_MASK 0xc000 |
| 221 | #define NSH_VER_SHIFT 14 |
| 222 | #define NSH_FLAGS_MASK 0x3000 |
| 223 | #define NSH_FLAGS_SHIFT 12 |
| 224 | #define NSH_TTL_MASK 0x0fc0 |
| 225 | #define NSH_TTL_SHIFT 6 |
| 226 | #define NSH_LEN_MASK 0x003f |
| 227 | #define NSH_LEN_SHIFT 0 |
| 228 | |
| 229 | #define NSH_MDTYPE_MASK 0x0f |
| 230 | #define NSH_MDTYPE_SHIFT 0 |
| 231 | |
| 232 | #define NSH_SPI_MASK 0xffffff00 |
| 233 | #define NSH_SPI_SHIFT 8 |
| 234 | #define NSH_SI_MASK 0x000000ff |
| 235 | #define NSH_SI_SHIFT 0 |
| 236 | |
| 237 | /* MD Type Registry. */ |
| 238 | #define NSH_M_TYPE1 0x01 |
| 239 | #define NSH_M_TYPE2 0x02 |
| 240 | #define NSH_M_EXP1 0xFE |
| 241 | #define NSH_M_EXP2 0xFF |
| 242 | |
| 243 | /* NSH Base Header Length */ |
| 244 | #define NSH_BASE_HDR_LEN 8 |
| 245 | |
| 246 | /* NSH MD Type 1 header Length. */ |
| 247 | #define NSH_M_TYPE1_LEN 24 |
| 248 | |
| 249 | /* NSH header maximum Length. */ |
| 250 | #define NSH_HDR_MAX_LEN 256 |
| 251 | |
| 252 | /* NSH context headers maximum Length. */ |
| 253 | #define NSH_CTX_HDRS_MAX_LEN 248 |
| 254 | |
| 255 | static inline struct nshhdr *nsh_hdr(struct sk_buff *skb) |
| 256 | { |
| 257 | return (struct nshhdr *)skb_network_header(skb); |
| 258 | } |
| 259 | |
| 260 | static inline u16 nsh_hdr_len(const struct nshhdr *nsh) |
| 261 | { |
| 262 | return ((ntohs(nsh->ver_flags_ttl_len) & NSH_LEN_MASK) |
| 263 | >> NSH_LEN_SHIFT) << 2; |
| 264 | } |
| 265 | |
| 266 | static inline u8 nsh_get_ver(const struct nshhdr *nsh) |
| 267 | { |
| 268 | return (ntohs(nsh->ver_flags_ttl_len) & NSH_VER_MASK) |
| 269 | >> NSH_VER_SHIFT; |
| 270 | } |
| 271 | |
| 272 | static inline u8 nsh_get_flags(const struct nshhdr *nsh) |
| 273 | { |
| 274 | return (ntohs(nsh->ver_flags_ttl_len) & NSH_FLAGS_MASK) |
| 275 | >> NSH_FLAGS_SHIFT; |
| 276 | } |
| 277 | |
| 278 | static inline u8 nsh_get_ttl(const struct nshhdr *nsh) |
| 279 | { |
| 280 | return (ntohs(nsh->ver_flags_ttl_len) & NSH_TTL_MASK) |
| 281 | >> NSH_TTL_SHIFT; |
| 282 | } |
| 283 | |
| 284 | static inline void __nsh_set_xflag(struct nshhdr *nsh, u16 xflag, u16 xmask) |
| 285 | { |
| 286 | nsh->ver_flags_ttl_len |
| 287 | = (nsh->ver_flags_ttl_len & ~htons(xmask)) | htons(xflag); |
| 288 | } |
| 289 | |
| 290 | static inline void nsh_set_flags_and_ttl(struct nshhdr *nsh, u8 flags, u8 ttl) |
| 291 | { |
| 292 | __nsh_set_xflag(nsh, ((flags << NSH_FLAGS_SHIFT) & NSH_FLAGS_MASK) | |
| 293 | ((ttl << NSH_TTL_SHIFT) & NSH_TTL_MASK), |
| 294 | NSH_FLAGS_MASK | NSH_TTL_MASK); |
| 295 | } |
| 296 | |
| 297 | static inline void nsh_set_flags_ttl_len(struct nshhdr *nsh, u8 flags, |
| 298 | u8 ttl, u8 len) |
| 299 | { |
| 300 | len = len >> 2; |
| 301 | __nsh_set_xflag(nsh, ((flags << NSH_FLAGS_SHIFT) & NSH_FLAGS_MASK) | |
| 302 | ((ttl << NSH_TTL_SHIFT) & NSH_TTL_MASK) | |
| 303 | ((len << NSH_LEN_SHIFT) & NSH_LEN_MASK), |
| 304 | NSH_FLAGS_MASK | NSH_TTL_MASK | NSH_LEN_MASK); |
| 305 | } |
| 306 | |
| 307 | int nsh_push(struct sk_buff *skb, const struct nshhdr *pushed_nh); |
| 308 | int nsh_pop(struct sk_buff *skb); |
| 309 | |
| 310 | #endif /* __NET_NSH_H */ |
| 311 |
Warning: This file is not a C or C++ file. It does not have highlighting.