xref: /openbmc/linux/include/net/gue.h (revision 949d6b40)
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