/* Kernel module to match ESP parameters. */
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/* Kernel module to match ESP parameters. */
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#include <linux/module.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/skbuff.h>
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#include <linux/netfilter_ipv4/ipt_esp.h>
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#include <linux/netfilter_ipv4/ipt_esp.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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EXPORT_NO_SYMBOLS;
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EXPORT_NO_SYMBOLS;
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MODULE_LICENSE("GPL");
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MODULE_LICENSE("GPL");
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#ifdef DEBUG_CONNTRACK
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#ifdef DEBUG_CONNTRACK
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#define duprintf(format, args...) printk(format , ## args)
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#define duprintf(format, args...) printk(format , ## args)
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#else
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#else
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#define duprintf(format, args...)
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#define duprintf(format, args...)
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#endif
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#endif
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struct esphdr {
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struct esphdr {
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__u32 spi;
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__u32 spi;
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__u32 seq_no;
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__u32 seq_no;
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};
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};
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/* Returns 1 if the spi is matched by the range, 0 otherwise */
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/* Returns 1 if the spi is matched by the range, 0 otherwise */
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static inline int
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static inline int
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spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert)
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spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert)
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{
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{
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int r=0;
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int r=0;
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duprintf("esp spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
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duprintf("esp spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
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min,spi,max);
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min,spi,max);
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r=(spi >= min && spi <= max) ^ invert;
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r=(spi >= min && spi <= max) ^ invert;
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duprintf(" result %s\n",r? "PASS" : "FAILED");
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duprintf(" result %s\n",r? "PASS" : "FAILED");
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return r;
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return r;
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}
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}
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static int
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static int
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match(const struct sk_buff *skb,
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match(const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *in,
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const struct net_device *out,
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const struct net_device *out,
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const void *matchinfo,
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const void *matchinfo,
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int offset,
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int offset,
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const void *hdr,
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const void *hdr,
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u_int16_t datalen,
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u_int16_t datalen,
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int *hotdrop)
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int *hotdrop)
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{
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{
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const struct esphdr *esp = hdr;
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const struct esphdr *esp = hdr;
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const struct ipt_esp *espinfo = matchinfo;
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const struct ipt_esp *espinfo = matchinfo;
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if (offset == 0 && datalen < sizeof(struct esphdr)) {
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if (offset == 0 && datalen < sizeof(struct esphdr)) {
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/* We've been asked to examine this packet, and we
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/* We've been asked to examine this packet, and we
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can't. Hence, no choice but to drop. */
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can't. Hence, no choice but to drop. */
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duprintf("Dropping evil ESP tinygram.\n");
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duprintf("Dropping evil ESP tinygram.\n");
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*hotdrop = 1;
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*hotdrop = 1;
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return 0;
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return 0;
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}
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}
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/* Must not be a fragment. */
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/* Must not be a fragment. */
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return !offset
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return !offset
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&& spi_match(espinfo->spis[0], espinfo->spis[1],
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&& spi_match(espinfo->spis[0], espinfo->spis[1],
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ntohl(esp->spi),
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ntohl(esp->spi),
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!!(espinfo->invflags & IPT_ESP_INV_SPI));
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!!(espinfo->invflags & IPT_ESP_INV_SPI));
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}
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}
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/* Called when user tries to insert an entry of this type. */
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/* Called when user tries to insert an entry of this type. */
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static int
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static int
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checkentry(const char *tablename,
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checkentry(const char *tablename,
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const struct ipt_ip *ip,
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const struct ipt_ip *ip,
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void *matchinfo,
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void *matchinfo,
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unsigned int matchinfosize,
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unsigned int matchinfosize,
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unsigned int hook_mask)
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unsigned int hook_mask)
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{
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{
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const struct ipt_esp *espinfo = matchinfo;
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const struct ipt_esp *espinfo = matchinfo;
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/* Must specify proto == ESP, and no unknown invflags */
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/* Must specify proto == ESP, and no unknown invflags */
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if (ip->proto != IPPROTO_ESP || (ip->invflags & IPT_INV_PROTO)) {
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if (ip->proto != IPPROTO_ESP || (ip->invflags & IPT_INV_PROTO)) {
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duprintf("ipt_esp: Protocol %u != %u\n", ip->proto,
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duprintf("ipt_esp: Protocol %u != %u\n", ip->proto,
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IPPROTO_ESP);
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IPPROTO_ESP);
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return 0;
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return 0;
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}
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}
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if (matchinfosize != IPT_ALIGN(sizeof(struct ipt_esp))) {
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if (matchinfosize != IPT_ALIGN(sizeof(struct ipt_esp))) {
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duprintf("ipt_esp: matchsize %u != %u\n",
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duprintf("ipt_esp: matchsize %u != %u\n",
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matchinfosize, IPT_ALIGN(sizeof(struct ipt_esp)));
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matchinfosize, IPT_ALIGN(sizeof(struct ipt_esp)));
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return 0;
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return 0;
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}
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}
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if (espinfo->invflags & ~IPT_ESP_INV_MASK) {
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if (espinfo->invflags & ~IPT_ESP_INV_MASK) {
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duprintf("ipt_esp: unknown flags %X\n",
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duprintf("ipt_esp: unknown flags %X\n",
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espinfo->invflags);
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espinfo->invflags);
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return 0;
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return 0;
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}
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}
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return 1;
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return 1;
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}
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}
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static struct ipt_match esp_match
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static struct ipt_match esp_match
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= { { NULL, NULL }, "esp", &match, &checkentry, NULL, THIS_MODULE };
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= { { NULL, NULL }, "esp", &match, &checkentry, NULL, THIS_MODULE };
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static int __init init(void)
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static int __init init(void)
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{
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{
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return ipt_register_match(&esp_match);
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return ipt_register_match(&esp_match);
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}
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}
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static void __exit cleanup(void)
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static void __exit cleanup(void)
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{
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{
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ipt_unregister_match(&esp_match);
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ipt_unregister_match(&esp_match);
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}
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}
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module_init(init);
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module_init(init);
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module_exit(cleanup);
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module_exit(cleanup);
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