include/net/gue.h

   1 #ifndef __NET_GUE_H
   2 #define __NET_GUE_H
   3
   4 /* Definitions for the GUE header, standard and private flags, lengths
   5  * of optional fields are below.
   6  *
   7  * Diagram of GUE header:
   8  *
   9  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  10  * |Ver|C|  Hlen   | Proto/ctype   |        Standard flags       |P|
  11  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  12  * |                                                               |
  13  * ~                      Fields (optional)                        ~
  14  * |                                                               |
  15  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  16  * |            Private flags (optional, P bit is set)             |
  17  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  18  * |                                                               |
  19  * ~                   Private fields (optional)                   ~
  20  * |                                                               |
  21  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  22  *
  23  * C bit indicates contol message when set, data message when unset.
  24  * For a control message, proto/ctype is interpreted as a type of
  25  * control message. For data messages, proto/ctype is the IP protocol
  26  * of the next header.
  27  *
  28  * P bit indicates private flags field is present. The private flags
  29  * may refer to options placed after this field.
  30  */
  31
  32 struct guehdr {
  33         union {
  34                 struct {
  35 #if defined(__LITTLE_ENDIAN_BITFIELD)
  36                         __u8    hlen:5,
  37                                 control:1,
  38                                 version:2;
  39 #elif defined (__BIG_ENDIAN_BITFIELD)
  40                         __u8    version:2,
  41                                 control:1,
  42                                 hlen:5;
  43 #else
  44 #error  "Please fix <asm/byteorder.h>"
  45 #endif
  46                         __u8    proto_ctype;
  47                         __u16   flags;
  48                 };
  49                 __u32 word;
  50         };
  51 };
  52
  53 /* Standard flags in GUE header */
  54
  55 #define GUE_FLAG_PRIV   htons(1<<0)     /* Private flags are in options */
  56 #define GUE_LEN_PRIV    4
  57
  58 #define GUE_FLAGS_ALL   (GUE_FLAG_PRIV)
  59
  60 /* Private flags in the private option extension */
  61
  62 #define GUE_PFLAG_REMCSUM       htonl(1 << 31)
  63 #define GUE_PLEN_REMCSUM        4
  64
  65 #define GUE_PFLAGS_ALL  (GUE_PFLAG_REMCSUM)
  66
  67 /* Functions to compute options length corresponding to flags.
  68  * If we ever have a lot of flags this can be potentially be
  69  * converted to a more optimized algorithm (table lookup
  70  * for instance).
  71  */
  72 static inline size_t guehdr_flags_len(__be16 flags)
  73 {
  74         return ((flags & GUE_FLAG_PRIV) ? GUE_LEN_PRIV : 0);
  75 }
  76
  77 static inline size_t guehdr_priv_flags_len(__be32 flags)
  78 {
  79         return 0;
  80 }
  81
  82 /* Validate standard and private flags. Returns non-zero (meaning invalid)
  83  * if there is an unknown standard or private flags, or the options length for
  84  * the flags exceeds the options length specific in hlen of the GUE header.
  85  */
  86 static inline int validate_gue_flags(struct guehdr *guehdr,
  87                                      size_t optlen)
  88 {
  89         size_t len;
  90         __be32 flags = guehdr->flags;
  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                 flags = *(__be32 *)((void *)&guehdr[1] + len - GUE_LEN_PRIV);
 104
 105                 if (flags & ~GUE_PFLAGS_ALL)
 106                         return 1;
 107
 108                 len += guehdr_priv_flags_len(flags);
 109                 if (len > optlen)
 110                         return 1;
 111         }
 112
 113         return 0;
 114 }
 115
 116 #endif