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37dd0247 TH |
1 | #ifndef __NET_GUE_H |
2 | #define __NET_GUE_H | |
3 | ||
5024c33a TH |
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 | ||
37dd0247 TH |
32 | struct guehdr { |
33 | union { | |
34 | struct { | |
35 | #if defined(__LITTLE_ENDIAN_BITFIELD) | |
5024c33a TH |
36 | __u8 hlen:5, |
37 | control:1, | |
38 | version:2; | |
37dd0247 | 39 | #elif defined (__BIG_ENDIAN_BITFIELD) |
5024c33a TH |
40 | __u8 version:2, |
41 | control:1, | |
42 | hlen:5; | |
37dd0247 TH |
43 | #else |
44 | #error "Please fix <asm/byteorder.h>" | |
45 | #endif | |
5024c33a | 46 | __u8 proto_ctype; |
37dd0247 TH |
47 | __u16 flags; |
48 | }; | |
49 | __u32 word; | |
50 | }; | |
51 | }; | |
52 | ||
5024c33a TH |
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 | ||
c1aa8347 TH |
62 | #define GUE_PFLAG_REMCSUM htonl(1 << 31) |
63 | #define GUE_PLEN_REMCSUM 4 | |
64 | ||
65 | #define GUE_PFLAGS_ALL (GUE_PFLAG_REMCSUM) | |
5024c33a TH |
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 | ||
37dd0247 | 116 | #endif |