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-rw-r--r--net/netfilter/xt_socket.c336
1 files changed, 336 insertions, 0 deletions
diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c
new file mode 100644
index 000000000..76e01f292
--- /dev/null
+++ b/net/netfilter/xt_socket.c
@@ -0,0 +1,336 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Transparent proxy support for Linux/iptables
+ *
+ * Copyright (C) 2007-2008 BalaBit IT Ltd.
+ * Author: Krisztian Kovacs
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <net/tcp.h>
+#include <net/udp.h>
+#include <net/icmp.h>
+#include <net/sock.h>
+#include <net/inet_sock.h>
+#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
+
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#include <net/inet6_hashtables.h>
+#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
+#endif
+
+#include <net/netfilter/nf_socket.h>
+#include <linux/netfilter/xt_socket.h>
+
+/* "socket" match based redirection (no specific rule)
+ * ===================================================
+ *
+ * There are connections with dynamic endpoints (e.g. FTP data
+ * connection) that the user is unable to add explicit rules
+ * for. These are taken care of by a generic "socket" rule. It is
+ * assumed that the proxy application is trusted to open such
+ * connections without explicit iptables rule (except of course the
+ * generic 'socket' rule). In this case the following sockets are
+ * matched in preference order:
+ *
+ * - match: if there's a fully established connection matching the
+ * _packet_ tuple
+ *
+ * - match: if there's a non-zero bound listener (possibly with a
+ * non-local address) We don't accept zero-bound listeners, since
+ * then local services could intercept traffic going through the
+ * box.
+ */
+static bool
+socket_match(const struct sk_buff *skb, struct xt_action_param *par,
+ const struct xt_socket_mtinfo1 *info)
+{
+ struct sk_buff *pskb = (struct sk_buff *)skb;
+ struct sock *sk = skb->sk;
+
+ if (sk && !net_eq(xt_net(par), sock_net(sk)))
+ sk = NULL;
+
+ if (!sk)
+ sk = nf_sk_lookup_slow_v4(xt_net(par), skb, xt_in(par));
+
+ if (sk) {
+ bool wildcard;
+ bool transparent = true;
+
+ /* Ignore sockets listening on INADDR_ANY,
+ * unless XT_SOCKET_NOWILDCARD is set
+ */
+ wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
+ sk_fullsock(sk) &&
+ inet_sk(sk)->inet_rcv_saddr == 0);
+
+ /* Ignore non-transparent sockets,
+ * if XT_SOCKET_TRANSPARENT is used
+ */
+ if (info->flags & XT_SOCKET_TRANSPARENT)
+ transparent = inet_sk_transparent(sk);
+
+ if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&
+ transparent && sk_fullsock(sk))
+ pskb->mark = READ_ONCE(sk->sk_mark);
+
+ if (sk != skb->sk)
+ sock_gen_put(sk);
+
+ if (wildcard || !transparent)
+ sk = NULL;
+ }
+
+ return sk != NULL;
+}
+
+static bool
+socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par)
+{
+ static struct xt_socket_mtinfo1 xt_info_v0 = {
+ .flags = 0,
+ };
+
+ return socket_match(skb, par, &xt_info_v0);
+}
+
+static bool
+socket_mt4_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)
+{
+ return socket_match(skb, par, par->matchinfo);
+}
+
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+static bool
+socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)
+{
+ const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
+ struct sk_buff *pskb = (struct sk_buff *)skb;
+ struct sock *sk = skb->sk;
+
+ if (sk && !net_eq(xt_net(par), sock_net(sk)))
+ sk = NULL;
+
+ if (!sk)
+ sk = nf_sk_lookup_slow_v6(xt_net(par), skb, xt_in(par));
+
+ if (sk) {
+ bool wildcard;
+ bool transparent = true;
+
+ /* Ignore sockets listening on INADDR_ANY
+ * unless XT_SOCKET_NOWILDCARD is set
+ */
+ wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
+ sk_fullsock(sk) &&
+ ipv6_addr_any(&sk->sk_v6_rcv_saddr));
+
+ /* Ignore non-transparent sockets,
+ * if XT_SOCKET_TRANSPARENT is used
+ */
+ if (info->flags & XT_SOCKET_TRANSPARENT)
+ transparent = inet_sk_transparent(sk);
+
+ if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&
+ transparent && sk_fullsock(sk))
+ pskb->mark = READ_ONCE(sk->sk_mark);
+
+ if (sk != skb->sk)
+ sock_gen_put(sk);
+
+ if (wildcard || !transparent)
+ sk = NULL;
+ }
+
+ return sk != NULL;
+}
+#endif
+
+static int socket_mt_enable_defrag(struct net *net, int family)
+{
+ switch (family) {
+ case NFPROTO_IPV4:
+ return nf_defrag_ipv4_enable(net);
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+ case NFPROTO_IPV6:
+ return nf_defrag_ipv6_enable(net);
+#endif
+ }
+ WARN_ONCE(1, "Unknown family %d\n", family);
+ return 0;
+}
+
+static int socket_mt_v1_check(const struct xt_mtchk_param *par)
+{
+ const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
+ int err;
+
+ err = socket_mt_enable_defrag(par->net, par->family);
+ if (err)
+ return err;
+
+ if (info->flags & ~XT_SOCKET_FLAGS_V1) {
+ pr_info_ratelimited("unknown flags 0x%x\n",
+ info->flags & ~XT_SOCKET_FLAGS_V1);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static int socket_mt_v2_check(const struct xt_mtchk_param *par)
+{
+ const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo;
+ int err;
+
+ err = socket_mt_enable_defrag(par->net, par->family);
+ if (err)
+ return err;
+
+ if (info->flags & ~XT_SOCKET_FLAGS_V2) {
+ pr_info_ratelimited("unknown flags 0x%x\n",
+ info->flags & ~XT_SOCKET_FLAGS_V2);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static int socket_mt_v3_check(const struct xt_mtchk_param *par)
+{
+ const struct xt_socket_mtinfo3 *info =
+ (struct xt_socket_mtinfo3 *)par->matchinfo;
+ int err;
+
+ err = socket_mt_enable_defrag(par->net, par->family);
+ if (err)
+ return err;
+ if (info->flags & ~XT_SOCKET_FLAGS_V3) {
+ pr_info_ratelimited("unknown flags 0x%x\n",
+ info->flags & ~XT_SOCKET_FLAGS_V3);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static void socket_mt_destroy(const struct xt_mtdtor_param *par)
+{
+ if (par->family == NFPROTO_IPV4)
+ nf_defrag_ipv4_disable(par->net);
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+ else if (par->family == NFPROTO_IPV6)
+ nf_defrag_ipv6_disable(par->net);
+#endif
+}
+
+static struct xt_match socket_mt_reg[] __read_mostly = {
+ {
+ .name = "socket",
+ .revision = 0,
+ .family = NFPROTO_IPV4,
+ .match = socket_mt4_v0,
+ .hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN),
+ .me = THIS_MODULE,
+ },
+ {
+ .name = "socket",
+ .revision = 1,
+ .family = NFPROTO_IPV4,
+ .match = socket_mt4_v1_v2_v3,
+ .destroy = socket_mt_destroy,
+ .checkentry = socket_mt_v1_check,
+ .matchsize = sizeof(struct xt_socket_mtinfo1),
+ .hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN),
+ .me = THIS_MODULE,
+ },
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+ {
+ .name = "socket",
+ .revision = 1,
+ .family = NFPROTO_IPV6,
+ .match = socket_mt6_v1_v2_v3,
+ .checkentry = socket_mt_v1_check,
+ .matchsize = sizeof(struct xt_socket_mtinfo1),
+ .destroy = socket_mt_destroy,
+ .hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN),
+ .me = THIS_MODULE,
+ },
+#endif
+ {
+ .name = "socket",
+ .revision = 2,
+ .family = NFPROTO_IPV4,
+ .match = socket_mt4_v1_v2_v3,
+ .checkentry = socket_mt_v2_check,
+ .destroy = socket_mt_destroy,
+ .matchsize = sizeof(struct xt_socket_mtinfo1),
+ .hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN),
+ .me = THIS_MODULE,
+ },
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+ {
+ .name = "socket",
+ .revision = 2,
+ .family = NFPROTO_IPV6,
+ .match = socket_mt6_v1_v2_v3,
+ .checkentry = socket_mt_v2_check,
+ .destroy = socket_mt_destroy,
+ .matchsize = sizeof(struct xt_socket_mtinfo1),
+ .hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN),
+ .me = THIS_MODULE,
+ },
+#endif
+ {
+ .name = "socket",
+ .revision = 3,
+ .family = NFPROTO_IPV4,
+ .match = socket_mt4_v1_v2_v3,
+ .checkentry = socket_mt_v3_check,
+ .destroy = socket_mt_destroy,
+ .matchsize = sizeof(struct xt_socket_mtinfo1),
+ .hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN),
+ .me = THIS_MODULE,
+ },
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+ {
+ .name = "socket",
+ .revision = 3,
+ .family = NFPROTO_IPV6,
+ .match = socket_mt6_v1_v2_v3,
+ .checkentry = socket_mt_v3_check,
+ .destroy = socket_mt_destroy,
+ .matchsize = sizeof(struct xt_socket_mtinfo1),
+ .hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN),
+ .me = THIS_MODULE,
+ },
+#endif
+};
+
+static int __init socket_mt_init(void)
+{
+ return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
+}
+
+static void __exit socket_mt_exit(void)
+{
+ xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
+}
+
+module_init(socket_mt_init);
+module_exit(socket_mt_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
+MODULE_DESCRIPTION("x_tables socket match module");
+MODULE_ALIAS("ipt_socket");
+MODULE_ALIAS("ip6t_socket");
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-18 13:48:38 +0000