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>

1 files changed, 90 insertions, 0 deletions

diff --git a/include/uapi/linux/netfilter/nf_osf.h b/include/uapi/linux/netfilter/nf_osf.h
new file mode 100644
index 000000000000..45376eae31ef
--- /dev/null
+++ b/include/uapi/linux/netfilter/nf_osf.h
@@ -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 */