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-rw-r--r--net/netfilter/nf_conntrack_irc.c314
1 files changed, 314 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_irc.c b/net/netfilter/nf_conntrack_irc.c
new file mode 100644
index 000000000..5703846be
--- /dev/null
+++ b/net/netfilter/nf_conntrack_irc.c
@@ -0,0 +1,314 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* IRC extension for IP connection tracking, Version 1.21
+ * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org>
+ * based on RR's ip_conntrack_ftp.c
+ * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/skbuff.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/netfilter.h>
+#include <linux/slab.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <linux/netfilter/nf_conntrack_irc.h>
+
+#define MAX_PORTS 8
+static unsigned short ports[MAX_PORTS];
+static unsigned int ports_c;
+static unsigned int max_dcc_channels = 8;
+static unsigned int dcc_timeout __read_mostly = 300;
+/* This is slow, but it's simple. --RR */
+static char *irc_buffer;
+static DEFINE_SPINLOCK(irc_buffer_lock);
+
+unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb,
+ enum ip_conntrack_info ctinfo,
+ unsigned int protoff,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct nf_conntrack_expect *exp) __read_mostly;
+EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
+
+#define HELPER_NAME "irc"
+#define MAX_SEARCH_SIZE 4095
+
+MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ip_conntrack_irc");
+MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
+
+module_param_array(ports, ushort, &ports_c, 0400);
+MODULE_PARM_DESC(ports, "port numbers of IRC servers");
+module_param(max_dcc_channels, uint, 0400);
+MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
+ "IRC session");
+module_param(dcc_timeout, uint, 0400);
+MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
+
+static const char *const dccprotos[] = {
+ "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
+};
+
+#define MINMATCHLEN 5
+
+/* tries to get the ip_addr and port out of a dcc command
+ * return value: -1 on failure, 0 on success
+ * data pointer to first byte of DCC command data
+ * data_end pointer to last byte of dcc command data
+ * ip returns parsed ip of dcc command
+ * port returns parsed port of dcc command
+ * ad_beg_p returns pointer to first byte of addr data
+ * ad_end_p returns pointer to last byte of addr data
+ */
+static int parse_dcc(char *data, const char *data_end, __be32 *ip,
+ u_int16_t *port, char **ad_beg_p, char **ad_end_p)
+{
+ char *tmp;
+
+ /* at least 12: "AAAAAAAA P\1\n" */
+ while (*data++ != ' ')
+ if (data > data_end - 12)
+ return -1;
+
+ /* Make sure we have a newline character within the packet boundaries
+ * because simple_strtoul parses until the first invalid character. */
+ for (tmp = data; tmp <= data_end; tmp++)
+ if (*tmp == '\n')
+ break;
+ if (tmp > data_end || *tmp != '\n')
+ return -1;
+
+ *ad_beg_p = data;
+ *ip = cpu_to_be32(simple_strtoul(data, &data, 10));
+
+ /* skip blanks between ip and port */
+ while (*data == ' ') {
+ if (data >= data_end)
+ return -1;
+ data++;
+ }
+
+ *port = simple_strtoul(data, &data, 10);
+ *ad_end_p = data;
+
+ return 0;
+}
+
+static int help(struct sk_buff *skb, unsigned int protoff,
+ struct nf_conn *ct, enum ip_conntrack_info ctinfo)
+{
+ unsigned int dataoff;
+ const struct iphdr *iph;
+ const struct tcphdr *th;
+ struct tcphdr _tcph;
+ const char *data_limit;
+ char *data, *ib_ptr;
+ int dir = CTINFO2DIR(ctinfo);
+ struct nf_conntrack_expect *exp;
+ struct nf_conntrack_tuple *tuple;
+ __be32 dcc_ip;
+ u_int16_t dcc_port;
+ __be16 port;
+ int i, ret = NF_ACCEPT;
+ char *addr_beg_p, *addr_end_p;
+ typeof(nf_nat_irc_hook) nf_nat_irc;
+ unsigned int datalen;
+
+ /* If packet is coming from IRC server */
+ if (dir == IP_CT_DIR_REPLY)
+ return NF_ACCEPT;
+
+ /* Until there's been traffic both ways, don't look in packets. */
+ if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
+ return NF_ACCEPT;
+
+ /* Not a full tcp header? */
+ th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
+ if (th == NULL)
+ return NF_ACCEPT;
+
+ /* No data? */
+ dataoff = protoff + th->doff*4;
+ if (dataoff >= skb->len)
+ return NF_ACCEPT;
+
+ datalen = skb->len - dataoff;
+ if (datalen > MAX_SEARCH_SIZE)
+ datalen = MAX_SEARCH_SIZE;
+
+ spin_lock_bh(&irc_buffer_lock);
+ ib_ptr = skb_header_pointer(skb, dataoff, datalen,
+ irc_buffer);
+ if (!ib_ptr) {
+ spin_unlock_bh(&irc_buffer_lock);
+ return NF_ACCEPT;
+ }
+
+ data = ib_ptr;
+ data_limit = ib_ptr + datalen;
+
+ /* Skip any whitespace */
+ while (data < data_limit - 10) {
+ if (*data == ' ' || *data == '\r' || *data == '\n')
+ data++;
+ else
+ break;
+ }
+
+ /* strlen("PRIVMSG x ")=10 */
+ if (data < data_limit - 10) {
+ if (strncasecmp("PRIVMSG ", data, 8))
+ goto out;
+ data += 8;
+ }
+
+ /* strlen(" :\1DCC SENT t AAAAAAAA P\1\n")=26
+ * 7+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=26
+ */
+ while (data < data_limit - (21 + MINMATCHLEN)) {
+ /* Find first " :", the start of message */
+ if (memcmp(data, " :", 2)) {
+ data++;
+ continue;
+ }
+ data += 2;
+
+ /* then check that place only for the DCC command */
+ if (memcmp(data, "\1DCC ", 5))
+ goto out;
+ data += 5;
+ /* we have at least (21+MINMATCHLEN)-(2+5) bytes valid data left */
+
+ iph = ip_hdr(skb);
+ pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
+ &iph->saddr, ntohs(th->source),
+ &iph->daddr, ntohs(th->dest));
+
+ for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
+ if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
+ /* no match */
+ continue;
+ }
+ data += strlen(dccprotos[i]);
+ pr_debug("DCC %s detected\n", dccprotos[i]);
+
+ /* we have at least
+ * (21+MINMATCHLEN)-7-dccprotos[i].matchlen bytes valid
+ * data left (== 14/13 bytes) */
+ if (parse_dcc(data, data_limit, &dcc_ip,
+ &dcc_port, &addr_beg_p, &addr_end_p)) {
+ pr_debug("unable to parse dcc command\n");
+ continue;
+ }
+
+ pr_debug("DCC bound ip/port: %pI4:%u\n",
+ &dcc_ip, dcc_port);
+
+ /* dcc_ip can be the internal OR external (NAT'ed) IP */
+ tuple = &ct->tuplehash[dir].tuple;
+ if ((tuple->src.u3.ip != dcc_ip &&
+ ct->tuplehash[!dir].tuple.dst.u3.ip != dcc_ip) ||
+ dcc_port == 0) {
+ net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n",
+ &tuple->src.u3.ip,
+ &dcc_ip, dcc_port);
+ continue;
+ }
+
+ exp = nf_ct_expect_alloc(ct);
+ if (exp == NULL) {
+ nf_ct_helper_log(skb, ct,
+ "cannot alloc expectation");
+ ret = NF_DROP;
+ goto out;
+ }
+ tuple = &ct->tuplehash[!dir].tuple;
+ port = htons(dcc_port);
+ nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
+ tuple->src.l3num,
+ NULL, &tuple->dst.u3,
+ IPPROTO_TCP, NULL, &port);
+
+ nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
+ if (nf_nat_irc && ct->status & IPS_NAT_MASK)
+ ret = nf_nat_irc(skb, ctinfo, protoff,
+ addr_beg_p - ib_ptr,
+ addr_end_p - addr_beg_p,
+ exp);
+ else if (nf_ct_expect_related(exp, 0) != 0) {
+ nf_ct_helper_log(skb, ct,
+ "cannot add expectation");
+ ret = NF_DROP;
+ }
+ nf_ct_expect_put(exp);
+ goto out;
+ }
+ }
+ out:
+ spin_unlock_bh(&irc_buffer_lock);
+ return ret;
+}
+
+static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
+static struct nf_conntrack_expect_policy irc_exp_policy;
+
+static int __init nf_conntrack_irc_init(void)
+{
+ int i, ret;
+
+ if (max_dcc_channels < 1) {
+ pr_err("max_dcc_channels must not be zero\n");
+ return -EINVAL;
+ }
+
+ if (max_dcc_channels > NF_CT_EXPECT_MAX_CNT) {
+ pr_err("max_dcc_channels must not be more than %u\n",
+ NF_CT_EXPECT_MAX_CNT);
+ return -EINVAL;
+ }
+
+ irc_exp_policy.max_expected = max_dcc_channels;
+ irc_exp_policy.timeout = dcc_timeout;
+
+ irc_buffer = kmalloc(MAX_SEARCH_SIZE + 1, GFP_KERNEL);
+ if (!irc_buffer)
+ return -ENOMEM;
+
+ /* If no port given, default to standard irc port */
+ if (ports_c == 0)
+ ports[ports_c++] = IRC_PORT;
+
+ for (i = 0; i < ports_c; i++) {
+ nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, HELPER_NAME,
+ IRC_PORT, ports[i], i, &irc_exp_policy,
+ 0, help, NULL, THIS_MODULE);
+ }
+
+ ret = nf_conntrack_helpers_register(&irc[0], ports_c);
+ if (ret) {
+ pr_err("failed to register helpers\n");
+ kfree(irc_buffer);
+ return ret;
+ }
+
+ return 0;
+}
+
+static void __exit nf_conntrack_irc_fini(void)
+{
+ nf_conntrack_helpers_unregister(irc, ports_c);
+ kfree(irc_buffer);
+}
+
+module_init(nf_conntrack_irc_init);
+module_exit(nf_conntrack_irc_fini);
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-09 19:13:22 +0000