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
32struct 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 */
72static inline size_t guehdr_flags_len(__be16 flags)
73{
74	return ((flags & GUE_FLAG_PRIV) ? GUE_LEN_PRIV : 0);
75}
76
77static 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 */
86static 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
117