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 contol 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