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 #include <asm/byteorder.h>
34 #include <linux/types.h>
35
36 struct guehdr {
37 union {
38 struct {
39 #if defined(__LITTLE_ENDIAN_BITFIELD)
40 __u8 hlen:5,
41 control:1,
42 version:2;
43 #elif defined (__BIG_ENDIAN_BITFIELD)
44 __u8 version:2,
45 control:1,
46 hlen:5;
47 #else
48 #error "Please fix <asm/byteorder.h>"
49 #endif
50 __u8 proto_ctype;
51 __be16 flags;
52 };
53 __be32 word;
54 };
55 };
56
57 /* Standard flags in GUE header */
58
59 #define GUE_FLAG_PRIV htons(1<<0) /* Private flags are in options */
60 #define GUE_LEN_PRIV 4
61
62 #define GUE_FLAGS_ALL (GUE_FLAG_PRIV)
63
64 /* Private flags in the private option extension */
65
66 #define GUE_PFLAG_REMCSUM htonl(1U << 31)
67 #define GUE_PLEN_REMCSUM 4
68
69 #define GUE_PFLAGS_ALL (GUE_PFLAG_REMCSUM)
70
71 /* Functions to compute options length corresponding to flags.
72 * If we ever have a lot of flags this can be potentially be
73 * converted to a more optimized algorithm (table lookup
74 * for instance).
75 */
guehdr_flags_len(__be16 flags)76 static inline size_t guehdr_flags_len(__be16 flags)
77 {
78 return ((flags & GUE_FLAG_PRIV) ? GUE_LEN_PRIV : 0);
79 }
80
guehdr_priv_flags_len(__be32 flags)81 static inline size_t guehdr_priv_flags_len(__be32 flags)
82 {
83 return 0;
84 }
85
86 /* Validate standard and private flags. Returns non-zero (meaning invalid)
87 * if there is an unknown standard or private flags, or the options length for
88 * the flags exceeds the options length specific in hlen of the GUE header.
89 */
validate_gue_flags(struct guehdr * guehdr,size_t optlen)90 static inline int validate_gue_flags(struct guehdr *guehdr, size_t optlen)
91 {
92 __be16 flags = guehdr->flags;
93 size_t len;
94
95 if (flags & ~GUE_FLAGS_ALL)
96 return 1;
97
98 len = guehdr_flags_len(flags);
99 if (len > optlen)
100 return 1;
101
102 if (flags & GUE_FLAG_PRIV) {
103 /* Private flags are last four bytes accounted in
104 * guehdr_flags_len
105 */
106 __be32 pflags = *(__be32 *)((void *)&guehdr[1] +
107 len - GUE_LEN_PRIV);
108
109 if (pflags & ~GUE_PFLAGS_ALL)
110 return 1;
111
112 len += guehdr_priv_flags_len(pflags);
113 if (len > optlen)
114 return 1;
115 }
116
117 return 0;
118 }
119
120 #endif
121