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TOMOYO Linux Cross Reference
Linux/include/net/gue.h

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  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 
 33 struct 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  */
 73 static inline size_t guehdr_flags_len(__be16 flags)
 74 {
 75         return ((flags & GUE_FLAG_PRIV) ? GUE_LEN_PRIV : 0);
 76 }
 77 
 78 static 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  */
 87 static 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 

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