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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __NET_GUE_H
#define __NET_GUE_H
/* Definitions for the GUE header, standard and private flags, lengths
* of optional fields are below.
*
* Diagram of GUE header:
*
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |Ver|C| Hlen | Proto/ctype | Standard flags |P|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* ~ Fields (optional) ~
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Private flags (optional, P bit is set) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* ~ Private fields (optional) ~
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* C bit indicates control message when set, data message when unset.
* For a control message, proto/ctype is interpreted as a type of
* control message. For data messages, proto/ctype is the IP protocol
* of the next header.
*
* P bit indicates private flags field is present. The private flags
* may refer to options placed after this field.
*/
struct guehdr {
union {
struct {
#if defined(__LITTLE_ENDIAN_BITFIELD)
__u8 hlen:5,
control:1,
version:2;
#elif defined (__BIG_ENDIAN_BITFIELD)
__u8 version:2,
control:1,
hlen:5;
#else
#error "Please fix <asm/byteorder.h>"
#endif
__u8 proto_ctype;
__be16 flags;
};
__be32 word;
};
};
/* Standard flags in GUE header */
#define GUE_FLAG_PRIV htons(1<<0) /* Private flags are in options */
#define GUE_LEN_PRIV 4
#define GUE_FLAGS_ALL (GUE_FLAG_PRIV)
/* Private flags in the private option extension */
#define GUE_PFLAG_REMCSUM htonl(1U << 31)
#define GUE_PLEN_REMCSUM 4
#define GUE_PFLAGS_ALL (GUE_PFLAG_REMCSUM)
/* Functions to compute options length corresponding to flags.
* If we ever have a lot of flags this can be potentially be
* converted to a more optimized algorithm (table lookup
* for instance).
*/
static inline size_t guehdr_flags_len(__be16 flags)
{
return ((flags & GUE_FLAG_PRIV) ? GUE_LEN_PRIV : 0);
}
static inline size_t guehdr_priv_flags_len(__be32 flags)
{
return 0;
}
/* Validate standard and private flags. Returns non-zero (meaning invalid)
* if there is an unknown standard or private flags, or the options length for
* the flags exceeds the options length specific in hlen of the GUE header.
*/
static inline int validate_gue_flags(struct guehdr *guehdr, size_t optlen)
{
__be16 flags = guehdr->flags;
size_t len;
if (flags & ~GUE_FLAGS_ALL)
return 1;
len = guehdr_flags_len(flags);
if (len > optlen)
return 1;
if (flags & GUE_FLAG_PRIV) {
/* Private flags are last four bytes accounted in
* guehdr_flags_len
*/
__be32 pflags = *(__be32 *)((void *)&guehdr[1] +
len - GUE_LEN_PRIV);
if (pflags & ~GUE_PFLAGS_ALL)
return 1;
len += guehdr_priv_flags_len(pflags);
if (len > optlen)
return 1;
}
return 0;
}
#endif
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