LXR linux/include/net/gue.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __NET_GUE_H
   3#define __NET_GUE_H
   4
   5/* Definitions for the GUE header, standard and private flags, lengths
   6 * of optional fields are below.
   7 *
   8 * Diagram of GUE header:
   9 *
  10 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  11 * |Ver|C|  Hlen   | Proto/ctype   |        Standard flags       |P|
  12 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  13 * |                                                               |
  14 * ~                      Fields (optional)                        ~
  15 * |                                                               |
  16 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  17 * |            Private flags (optional, P bit is set)             |
  18 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  19 * |                                                               |
  20 * ~                   Private fields (optional)                   ~
  21 * |                                                               |
  22 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  23 *
  24 * C bit indicates control message when set, data message when unset.
  25 * For a control message, proto/ctype is interpreted as a type of
  26 * control message. For data messages, proto/ctype is the IP protocol
  27 * of the next header.
  28 *
  29 * P bit indicates private flags field is present. The private flags
  30 * may refer to options placed after this field.
  31 */
  32
  33struct guehdr {
  34        union {
  35                struct {
  36#if defined(__LITTLE_ENDIAN_BITFIELD)
  37                        __u8    hlen:5,
  38                                control:1,
  39                                version:2;
  40#elif defined (__BIG_ENDIAN_BITFIELD)
  41                        __u8    version:2,
  42                                control:1,
  43                                hlen:5;
  44#else
  45#error  "Please fix <asm/byteorder.h>"
  46#endif
  47                        __u8    proto_ctype;
  48                        __be16  flags;
  49                };
  50                __be32  word;
  51        };
  52};
  53
  54/* Standard flags in GUE header */
  55
  56#define GUE_FLAG_PRIV   htons(1<<0)     /* Private flags are in options */
  57#define GUE_LEN_PRIV    4
  58
  59#define GUE_FLAGS_ALL   (GUE_FLAG_PRIV)
  60
  61/* Private flags in the private option extension */
  62
  63#define GUE_PFLAG_REMCSUM       htonl(1U << 31)
  64#define GUE_PLEN_REMCSUM        4
  65
  66#define GUE_PFLAGS_ALL  (GUE_PFLAG_REMCSUM)
  67
  68/* Functions to compute options length corresponding to flags.
  69 * If we ever have a lot of flags this can be potentially be
  70 * converted to a more optimized algorithm (table lookup
  71 * for instance).
  72 */
  73static inline size_t guehdr_flags_len(__be16 flags)
  74{
  75        return ((flags & GUE_FLAG_PRIV) ? GUE_LEN_PRIV : 0);
  76}
  77
  78static inline size_t guehdr_priv_flags_len(__be32 flags)
  79{
  80        return 0;
  81}
  82
  83/* Validate standard and private flags. Returns non-zero (meaning invalid)
  84 * if there is an unknown standard or private flags, or the options length for
  85 * the flags exceeds the options length specific in hlen of the GUE header.
  86 */
  87static inline int validate_gue_flags(struct guehdr *guehdr, size_t optlen)
  88{
  89        __be16 flags = guehdr->flags;
  90        size_t len;
  91
  92        if (flags & ~GUE_FLAGS_ALL)
  93                return 1;
  94
  95        len = guehdr_flags_len(flags);
  96        if (len > optlen)
  97                return 1;
  98
  99        if (flags & GUE_FLAG_PRIV) {
 100                /* Private flags are last four bytes accounted in
 101                 * guehdr_flags_len
 102                 */
 103                __be32 pflags = *(__be32 *)((void *)&guehdr[1] +
 104                                            len - GUE_LEN_PRIV);
 105
 106                if (pflags & ~GUE_PFLAGS_ALL)
 107                        return 1;
 108
 109                len += guehdr_priv_flags_len(pflags);
 110                if (len > optlen)
 111                        return 1;
 112        }
 113
 114        return 0;
 115}
 116
 117#endif
 118