netfilter: extract Passive OS fingerprint infrastructure from xt_osf

Add nf_osf_ttl() and nf_osf_match() into nf_osf.c to prepare for
nf_tables support.

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Fernando Fernandez Mancera
2018-05-03 14:05:40 +02:00
committed by Pablo Neira Ayuso
parent 3f9c56a581
commit bfb15f2a95
7 changed files with 359 additions and 289 deletions

View File

@@ -0,0 +1,90 @@
#ifndef _NF_OSF_H
#define _NF_OSF_H
#define MAXGENRELEN 32
#define NF_OSF_GENRE (1 << 0)
#define NF_OSF_TTL (1 << 1)
#define NF_OSF_LOG (1 << 2)
#define NF_OSF_INVERT (1 << 3)
#define NF_OSF_LOGLEVEL_ALL 0 /* log all matched fingerprints */
#define NF_OSF_LOGLEVEL_FIRST 1 /* log only the first matced fingerprint */
#define NF_OSF_LOGLEVEL_ALL_KNOWN 2 /* do not log unknown packets */
#define NF_OSF_TTL_TRUE 0 /* True ip and fingerprint TTL comparison */
/* Do not compare ip and fingerprint TTL at all */
#define NF_OSF_TTL_NOCHECK 2
/* Wildcard MSS (kind of).
* It is used to implement a state machine for the different wildcard values
* of the MSS and window sizes.
*/
struct nf_osf_wc {
__u32 wc;
__u32 val;
};
/* This struct represents IANA options
* http://www.iana.org/assignments/tcp-parameters
*/
struct nf_osf_opt {
__u16 kind, length;
struct nf_osf_wc wc;
};
struct nf_osf_info {
char genre[MAXGENRELEN];
__u32 len;
__u32 flags;
__u32 loglevel;
__u32 ttl;
};
struct nf_osf_user_finger {
struct nf_osf_wc wss;
__u8 ttl, df;
__u16 ss, mss;
__u16 opt_num;
char genre[MAXGENRELEN];
char version[MAXGENRELEN];
char subtype[MAXGENRELEN];
/* MAX_IPOPTLEN is maximum if all options are NOPs or EOLs */
struct nf_osf_opt opt[MAX_IPOPTLEN];
};
struct nf_osf_finger {
struct rcu_head rcu_head;
struct list_head finger_entry;
struct nf_osf_user_finger finger;
};
struct nf_osf_nlmsg {
struct nf_osf_user_finger f;
struct iphdr ip;
struct tcphdr tcp;
};
/* Defines for IANA option kinds */
enum iana_options {
OSFOPT_EOL = 0, /* End of options */
OSFOPT_NOP, /* NOP */
OSFOPT_MSS, /* Maximum segment size */
OSFOPT_WSO, /* Window scale option */
OSFOPT_SACKP, /* SACK permitted */
OSFOPT_SACK, /* SACK */
OSFOPT_ECHO,
OSFOPT_ECHOREPLY,
OSFOPT_TS, /* Timestamp option */
OSFOPT_POCP, /* Partial Order Connection Permitted */
OSFOPT_POSP, /* Partial Order Service Profile */
/* Others are not used in the current OSF */
OSFOPT_EMPTY = 255,
};
#endif /* _NF_OSF_H */

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@@ -23,101 +23,29 @@
#include <linux/types.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/netfilter/nf_osf.h>
#define MAXGENRELEN 32
#define XT_OSF_GENRE NF_OSF_GENRE
#define XT_OSF_INVERT NF_OSF_INVERT
#define XT_OSF_GENRE (1<<0)
#define XT_OSF_TTL (1<<1)
#define XT_OSF_LOG (1<<2)
#define XT_OSF_INVERT (1<<3)
#define XT_OSF_TTL NF_OSF_TTL
#define XT_OSF_LOG NF_OSF_LOG
#define XT_OSF_LOGLEVEL_ALL 0 /* log all matched fingerprints */
#define XT_OSF_LOGLEVEL_FIRST 1 /* log only the first matced fingerprint */
#define XT_OSF_LOGLEVEL_ALL_KNOWN 2 /* do not log unknown packets */
#define XT_OSF_LOGLEVEL_ALL NF_OSF_LOGLEVEL_ALL
#define XT_OSF_LOGLEVEL_FIRST NF_OSF_LOGLEVEL_FIRST
#define XT_OSF_LOGLEVEL_ALL_KNOWN NF_OSF_LOGLEVEL_ALL_KNOWN
#define XT_OSF_TTL_TRUE 0 /* True ip and fingerprint TTL comparison */
#define XT_OSF_TTL_LESS 1 /* Check if ip TTL is less than fingerprint one */
#define XT_OSF_TTL_NOCHECK 2 /* Do not compare ip and fingerprint TTL at all */
#define XT_OSF_TTL_TRUE NF_OSF_TTL_TRUE
#define XT_OSF_TTL_NOCHECK NF_OSF_TTL_NOCHECK
struct xt_osf_info {
char genre[MAXGENRELEN];
__u32 len;
__u32 flags;
__u32 loglevel;
__u32 ttl;
};
#define XT_OSF_TTL_LESS 1 /* Check if ip TTL is less than fingerprint one */
/*
* Wildcard MSS (kind of).
* It is used to implement a state machine for the different wildcard values
* of the MSS and window sizes.
*/
struct xt_osf_wc {
__u32 wc;
__u32 val;
};
/*
* This struct represents IANA options
* http://www.iana.org/assignments/tcp-parameters
*/
struct xt_osf_opt {
__u16 kind, length;
struct xt_osf_wc wc;
};
struct xt_osf_user_finger {
struct xt_osf_wc wss;
__u8 ttl, df;
__u16 ss, mss;
__u16 opt_num;
char genre[MAXGENRELEN];
char version[MAXGENRELEN];
char subtype[MAXGENRELEN];
/* MAX_IPOPTLEN is maximum if all options are NOPs or EOLs */
struct xt_osf_opt opt[MAX_IPOPTLEN];
};
struct xt_osf_nlmsg {
struct xt_osf_user_finger f;
struct iphdr ip;
struct tcphdr tcp;
};
/* Defines for IANA option kinds */
enum iana_options {
OSFOPT_EOL = 0, /* End of options */
OSFOPT_NOP, /* NOP */
OSFOPT_MSS, /* Maximum segment size */
OSFOPT_WSO, /* Window scale option */
OSFOPT_SACKP, /* SACK permitted */
OSFOPT_SACK, /* SACK */
OSFOPT_ECHO,
OSFOPT_ECHOREPLY,
OSFOPT_TS, /* Timestamp option */
OSFOPT_POCP, /* Partial Order Connection Permitted */
OSFOPT_POSP, /* Partial Order Service Profile */
/* Others are not used in the current OSF */
OSFOPT_EMPTY = 255,
};
/*
* Initial window size option state machine: multiple of mss, mtu or
* plain numeric value. Can also be made as plain numeric value which
* is not a multiple of specified value.
*/
enum xt_osf_window_size_options {
OSF_WSS_PLAIN = 0,
OSF_WSS_MSS,
OSF_WSS_MTU,
OSF_WSS_MODULO,
OSF_WSS_MAX,
};
#define xt_osf_wc nf_osf_wc
#define xt_osf_opt nf_osf_opt
#define xt_osf_info nf_osf_info
#define xt_osf_user_finger nf_osf_user_finger
#define xt_osf_finger nf_osf_finger
#define xt_osf_nlmsg nf_osf_nlmsg
/*
* Add/remove fingerprint from the kernel.