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-rw-r--r--net/netfilter/Kconfig4
-rw-r--r--net/netfilter/Makefile1
-rw-r--r--net/netfilter/nf_osf.c218
-rw-r--r--net/netfilter/xt_osf.c202
4 files changed, 225 insertions, 200 deletions
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index f66586fb41cd..e25cdb3d51cb 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -444,6 +444,9 @@ config NETFILTER_SYNPROXY
endif # NF_CONNTRACK
+config NF_OSF
+ tristate 'Passive OS fingerprint infrastructure'
+
config NF_TABLES
select NETFILTER_NETLINK
tristate "Netfilter nf_tables support"
@@ -1358,6 +1361,7 @@ config NETFILTER_XT_MATCH_NFACCT
config NETFILTER_XT_MATCH_OSF
tristate '"osf" Passive OS fingerprint match'
depends on NETFILTER_ADVANCED && NETFILTER_NETLINK
+ select NF_OSF
help
This option selects the Passive OS Fingerprinting match module
that allows to passively match the remote operating system by
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index b37ce0bc9ab7..1aa710b5d384 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -101,6 +101,7 @@ obj-$(CONFIG_NFT_HASH) += nft_hash.o
obj-$(CONFIG_NFT_FIB) += nft_fib.o
obj-$(CONFIG_NFT_FIB_INET) += nft_fib_inet.o
obj-$(CONFIG_NFT_FIB_NETDEV) += nft_fib_netdev.o
+obj-$(CONFIG_NF_OSF) += nf_osf.o
# nf_tables netdev
obj-$(CONFIG_NFT_DUP_NETDEV) += nft_dup_netdev.o
diff --git a/net/netfilter/nf_osf.c b/net/netfilter/nf_osf.c
new file mode 100644
index 000000000000..5ba5c7bef2f9
--- /dev/null
+++ b/net/netfilter/nf_osf.c
@@ -0,0 +1,218 @@
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include <linux/capability.h>
+#include <linux/if.h>
+#include <linux/inetdevice.h>
+#include <linux/ip.h>
+#include <linux/list.h>
+#include <linux/rculist.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/tcp.h>
+
+#include <net/ip.h>
+#include <net/tcp.h>
+
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/netfilter/nf_log.h>
+#include <linux/netfilter/nf_osf.h>
+
+static inline int nf_osf_ttl(const struct sk_buff *skb,
+ const struct nf_osf_info *info,
+ unsigned char f_ttl)
+{
+ const struct iphdr *ip = ip_hdr(skb);
+
+ if (info->flags & NF_OSF_TTL) {
+ if (info->ttl == NF_OSF_TTL_TRUE)
+ return ip->ttl == f_ttl;
+ if (info->ttl == NF_OSF_TTL_NOCHECK)
+ return 1;
+ else if (ip->ttl <= f_ttl)
+ return 1;
+ else {
+ struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
+ int ret = 0;
+
+ for_ifa(in_dev) {
+ if (inet_ifa_match(ip->saddr, ifa)) {
+ ret = (ip->ttl == f_ttl);
+ break;
+ }
+ }
+ endfor_ifa(in_dev);
+
+ return ret;
+ }
+ }
+
+ return ip->ttl == f_ttl;
+}
+
+bool
+nf_osf_match(const struct sk_buff *skb, u_int8_t family,
+ int hooknum, struct net_device *in, struct net_device *out,
+ const struct nf_osf_info *info, struct net *net,
+ const struct list_head *nf_osf_fingers)
+{
+ const unsigned char *optp = NULL, *_optp = NULL;
+ unsigned int optsize = 0, check_WSS = 0;
+ int fmatch = FMATCH_WRONG, fcount = 0;
+ const struct iphdr *ip = ip_hdr(skb);
+ const struct nf_osf_user_finger *f;
+ unsigned char opts[MAX_IPOPTLEN];
+ const struct nf_osf_finger *kf;
+ u16 window, totlen, mss = 0;
+ const struct tcphdr *tcp;
+ struct tcphdr _tcph;
+ bool df;
+
+ tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), &_tcph);
+ if (!tcp)
+ return false;
+
+ if (!tcp->syn)
+ return false;
+
+ totlen = ntohs(ip->tot_len);
+ df = ntohs(ip->frag_off) & IP_DF;
+ window = ntohs(tcp->window);
+
+ if (tcp->doff * 4 > sizeof(struct tcphdr)) {
+ optsize = tcp->doff * 4 - sizeof(struct tcphdr);
+
+ _optp = optp = skb_header_pointer(skb, ip_hdrlen(skb) +
+ sizeof(struct tcphdr), optsize, opts);
+ }
+
+ list_for_each_entry_rcu(kf, &nf_osf_fingers[df], finger_entry) {
+ int foptsize, optnum;
+
+ f = &kf->finger;
+
+ if (!(info->flags & NF_OSF_LOG) && strcmp(info->genre, f->genre))
+ continue;
+
+ optp = _optp;
+ fmatch = FMATCH_WRONG;
+
+ if (totlen != f->ss || !nf_osf_ttl(skb, info, f->ttl))
+ continue;
+
+ /*
+ * Should not happen if userspace parser was written correctly.
+ */
+ if (f->wss.wc >= OSF_WSS_MAX)
+ continue;
+
+ /* Check options */
+
+ foptsize = 0;
+ for (optnum = 0; optnum < f->opt_num; ++optnum)
+ foptsize += f->opt[optnum].length;
+
+ if (foptsize > MAX_IPOPTLEN ||
+ optsize > MAX_IPOPTLEN ||
+ optsize != foptsize)
+ continue;
+
+ check_WSS = f->wss.wc;
+
+ for (optnum = 0; optnum < f->opt_num; ++optnum) {
+ if (f->opt[optnum].kind == (*optp)) {
+ __u32 len = f->opt[optnum].length;
+ const __u8 *optend = optp + len;
+
+ fmatch = FMATCH_OK;
+
+ switch (*optp) {
+ case OSFOPT_MSS:
+ mss = optp[3];
+ mss <<= 8;
+ mss |= optp[2];
+
+ mss = ntohs((__force __be16)mss);
+ break;
+ case OSFOPT_TS:
+ break;
+ }
+
+ optp = optend;
+ } else
+ fmatch = FMATCH_OPT_WRONG;
+
+ if (fmatch != FMATCH_OK)
+ break;
+ }
+
+ if (fmatch != FMATCH_OPT_WRONG) {
+ fmatch = FMATCH_WRONG;
+
+ switch (check_WSS) {
+ case OSF_WSS_PLAIN:
+ if (f->wss.val == 0 || window == f->wss.val)
+ fmatch = FMATCH_OK;
+ break;
+ case OSF_WSS_MSS:
+ /*
+ * Some smart modems decrease mangle MSS to
+ * SMART_MSS_2, so we check standard, decreased
+ * and the one provided in the fingerprint MSS
+ * values.
+ */
+#define SMART_MSS_1 1460
+#define SMART_MSS_2 1448
+ if (window == f->wss.val * mss ||
+ window == f->wss.val * SMART_MSS_1 ||
+ window == f->wss.val * SMART_MSS_2)
+ fmatch = FMATCH_OK;
+ break;
+ case OSF_WSS_MTU:
+ if (window == f->wss.val * (mss + 40) ||
+ window == f->wss.val * (SMART_MSS_1 + 40) ||
+ window == f->wss.val * (SMART_MSS_2 + 40))
+ fmatch = FMATCH_OK;
+ break;
+ case OSF_WSS_MODULO:
+ if ((window % f->wss.val) == 0)
+ fmatch = FMATCH_OK;
+ break;
+ }
+ }
+
+ if (fmatch != FMATCH_OK)
+ continue;
+
+ fcount++;
+
+ if (info->flags & NF_OSF_LOG)
+ nf_log_packet(net, family, hooknum, skb,
+ in, out, NULL,
+ "%s [%s:%s] : %pI4:%d -> %pI4:%d hops=%d\n",
+ f->genre, f->version, f->subtype,
+ &ip->saddr, ntohs(tcp->source),
+ &ip->daddr, ntohs(tcp->dest),
+ f->ttl - ip->ttl);
+
+ if ((info->flags & NF_OSF_LOG) &&
+ info->loglevel == NF_OSF_LOGLEVEL_FIRST)
+ break;
+ }
+
+ if (!fcount && (info->flags & NF_OSF_LOG))
+ nf_log_packet(net, family, hooknum, skb, in, out, NULL,
+ "Remote OS is not known: %pI4:%u -> %pI4:%u\n",
+ &ip->saddr, ntohs(tcp->source),
+ &ip->daddr, ntohs(tcp->dest));
+
+ if (fcount)
+ fmatch = FMATCH_OK;
+
+ return fmatch == FMATCH_OK;
+}
+EXPORT_SYMBOL_GPL(nf_osf_match);
+
+MODULE_LICENSE("GPL");
diff --git a/net/netfilter/xt_osf.c b/net/netfilter/xt_osf.c
index a34f314a8c23..9cfef73b4107 100644
--- a/net/netfilter/xt_osf.c
+++ b/net/netfilter/xt_osf.c
@@ -37,21 +37,6 @@
#include <net/netfilter/nf_log.h>
#include <linux/netfilter/xt_osf.h>
-struct xt_osf_finger {
- struct rcu_head rcu_head;
- struct list_head finger_entry;
- struct xt_osf_user_finger finger;
-};
-
-enum osf_fmatch_states {
- /* Packet does not match the fingerprint */
- FMATCH_WRONG = 0,
- /* Packet matches the fingerprint */
- FMATCH_OK,
- /* Options do not match the fingerprint, but header does */
- FMATCH_OPT_WRONG,
-};
-
/*
* Indexed by dont-fragment bit.
* It is the only constant value in the fingerprint.
@@ -164,200 +149,17 @@ static const struct nfnetlink_subsystem xt_osf_nfnetlink = {
.cb = xt_osf_nfnetlink_callbacks,
};
-static inline int xt_osf_ttl(const struct sk_buff *skb, const struct xt_osf_info *info,
- unsigned char f_ttl)
-{
- const struct iphdr *ip = ip_hdr(skb);
-
- if (info->flags & XT_OSF_TTL) {
- if (info->ttl == XT_OSF_TTL_TRUE)
- return ip->ttl == f_ttl;
- if (info->ttl == XT_OSF_TTL_NOCHECK)
- return 1;
- else if (ip->ttl <= f_ttl)
- return 1;
- else {
- struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
- int ret = 0;
-
- for_ifa(in_dev) {
- if (inet_ifa_match(ip->saddr, ifa)) {
- ret = (ip->ttl == f_ttl);
- break;
- }
- }
- endfor_ifa(in_dev);
-
- return ret;
- }
- }
-
- return ip->ttl == f_ttl;
-}
-
static bool
xt_osf_match_packet(const struct sk_buff *skb, struct xt_action_param *p)
{
const struct xt_osf_info *info = p->matchinfo;
- const struct iphdr *ip = ip_hdr(skb);
- const struct tcphdr *tcp;
- struct tcphdr _tcph;
- int fmatch = FMATCH_WRONG, fcount = 0;
- unsigned int optsize = 0, check_WSS = 0;
- u16 window, totlen, mss = 0;
- bool df;
- const unsigned char *optp = NULL, *_optp = NULL;
- unsigned char opts[MAX_IPOPTLEN];
- const struct xt_osf_finger *kf;
- const struct xt_osf_user_finger *f;
struct net *net = xt_net(p);
if (!info)
return false;
- tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), &_tcph);
- if (!tcp)
- return false;
-
- if (!tcp->syn)
- return false;
-
- totlen = ntohs(ip->tot_len);
- df = ntohs(ip->frag_off) & IP_DF;
- window = ntohs(tcp->window);
-
- if (tcp->doff * 4 > sizeof(struct tcphdr)) {
- optsize = tcp->doff * 4 - sizeof(struct tcphdr);
-
- _optp = optp = skb_header_pointer(skb, ip_hdrlen(skb) +
- sizeof(struct tcphdr), optsize, opts);
- }
-
- list_for_each_entry_rcu(kf, &xt_osf_fingers[df], finger_entry) {
- int foptsize, optnum;
-
- f = &kf->finger;
-
- if (!(info->flags & XT_OSF_LOG) && strcmp(info->genre, f->genre))
- continue;
-
- optp = _optp;
- fmatch = FMATCH_WRONG;
-
- if (totlen != f->ss || !xt_osf_ttl(skb, info, f->ttl))
- continue;
-
- /*
- * Should not happen if userspace parser was written correctly.
- */
- if (f->wss.wc >= OSF_WSS_MAX)
- continue;
-
- /* Check options */
-
- foptsize = 0;
- for (optnum = 0; optnum < f->opt_num; ++optnum)
- foptsize += f->opt[optnum].length;
-
- if (foptsize > MAX_IPOPTLEN ||
- optsize > MAX_IPOPTLEN ||
- optsize != foptsize)
- continue;
-
- check_WSS = f->wss.wc;
-
- for (optnum = 0; optnum < f->opt_num; ++optnum) {
- if (f->opt[optnum].kind == (*optp)) {
- __u32 len = f->opt[optnum].length;
- const __u8 *optend = optp + len;
-
- fmatch = FMATCH_OK;
-
- switch (*optp) {
- case OSFOPT_MSS:
- mss = optp[3];
- mss <<= 8;
- mss |= optp[2];
-
- mss = ntohs((__force __be16)mss);
- break;
- case OSFOPT_TS:
- break;
- }
-
- optp = optend;
- } else
- fmatch = FMATCH_OPT_WRONG;
-
- if (fmatch != FMATCH_OK)
- break;
- }
-
- if (fmatch != FMATCH_OPT_WRONG) {
- fmatch = FMATCH_WRONG;
-
- switch (check_WSS) {
- case OSF_WSS_PLAIN:
- if (f->wss.val == 0 || window == f->wss.val)
- fmatch = FMATCH_OK;
- break;
- case OSF_WSS_MSS:
- /*
- * Some smart modems decrease mangle MSS to
- * SMART_MSS_2, so we check standard, decreased
- * and the one provided in the fingerprint MSS
- * values.
- */
-#define SMART_MSS_1 1460
-#define SMART_MSS_2 1448
- if (window == f->wss.val * mss ||
- window == f->wss.val * SMART_MSS_1 ||
- window == f->wss.val * SMART_MSS_2)
- fmatch = FMATCH_OK;
- break;
- case OSF_WSS_MTU:
- if (window == f->wss.val * (mss + 40) ||
- window == f->wss.val * (SMART_MSS_1 + 40) ||
- window == f->wss.val * (SMART_MSS_2 + 40))
- fmatch = FMATCH_OK;
- break;
- case OSF_WSS_MODULO:
- if ((window % f->wss.val) == 0)
- fmatch = FMATCH_OK;
- break;
- }
- }
-
- if (fmatch != FMATCH_OK)
- continue;
-
- fcount++;
-
- if (info->flags & XT_OSF_LOG)
- nf_log_packet(net, xt_family(p), xt_hooknum(p), skb,
- xt_in(p), xt_out(p), NULL,
- "%s [%s:%s] : %pI4:%d -> %pI4:%d hops=%d\n",
- f->genre, f->version, f->subtype,
- &ip->saddr, ntohs(tcp->source),
- &ip->daddr, ntohs(tcp->dest),
- f->ttl - ip->ttl);
-
- if ((info->flags & XT_OSF_LOG) &&
- info->loglevel == XT_OSF_LOGLEVEL_FIRST)
- break;
- }
-
- if (!fcount && (info->flags & XT_OSF_LOG))
- nf_log_packet(net, xt_family(p), xt_hooknum(p), skb, xt_in(p),
- xt_out(p), NULL,
- "Remote OS is not known: %pI4:%u -> %pI4:%u\n",
- &ip->saddr, ntohs(tcp->source),
- &ip->daddr, ntohs(tcp->dest));
-
- if (fcount)
- fmatch = FMATCH_OK;
-
- return fmatch == FMATCH_OK;
+ return nf_osf_match(skb, xt_family(p), xt_hooknum(p), xt_in(p),
+ xt_out(p), info, net, xt_osf_fingers);
}
static struct xt_match xt_osf_match = {
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-28 03:45:59 +0000