diff options
Diffstat (limited to 'net/ipv6/netfilter/ip6t_ah.c')
| -rw-r--r-- | net/ipv6/netfilter/ip6t_ah.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/ip6t_ah.c b/net/ipv6/netfilter/ip6t_ah.c new file mode 100644 index 00000000000..d5b94f142bb --- /dev/null +++ b/net/ipv6/netfilter/ip6t_ah.c @@ -0,0 +1,208 @@ +/* Kernel module to match AH parameters. */ + +/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/ipv6.h> +#include <linux/types.h> +#include <net/checksum.h> +#include <net/ipv6.h> + +#include <linux/netfilter_ipv6/ip6_tables.h> +#include <linux/netfilter_ipv6/ip6t_ah.h> + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("IPv6 AH match"); +MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); + +#if 0 +#define DEBUGP printk +#else +#define DEBUGP(format, args...) +#endif + +/* Returns 1 if the spi is matched by the range, 0 otherwise */ +static inline int +spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert) +{ + int r=0; + DEBUGP("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ', + min,spi,max); + r = (spi >= min && spi <= max) ^ invert; + DEBUGP(" result %s\n",r? "PASS\n" : "FAILED\n"); + return r; +} + +static int +match(const struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + const void *matchinfo, + int offset, + unsigned int protoff, + int *hotdrop) +{ + struct ip_auth_hdr *ah = NULL, _ah; + const struct ip6t_ah *ahinfo = matchinfo; + unsigned int temp; + int len; + u8 nexthdr; + unsigned int ptr; + unsigned int hdrlen = 0; + + /*DEBUGP("IPv6 AH entered\n");*/ + /* if (opt->auth == 0) return 0; + * It does not filled on output */ + + /* type of the 1st exthdr */ + nexthdr = skb->nh.ipv6h->nexthdr; + /* pointer to the 1st exthdr */ + ptr = sizeof(struct ipv6hdr); + /* available length */ + len = skb->len - ptr; + temp = 0; + + while (ip6t_ext_hdr(nexthdr)) { + struct ipv6_opt_hdr _hdr, *hp; + + DEBUGP("ipv6_ah header iteration \n"); + + /* Is there enough space for the next ext header? */ + if (len < sizeof(struct ipv6_opt_hdr)) + return 0; + /* No more exthdr -> evaluate */ + if (nexthdr == NEXTHDR_NONE) + break; + /* ESP -> evaluate */ + if (nexthdr == NEXTHDR_ESP) + break; + + hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr); + BUG_ON(hp == NULL); + + /* Calculate the header length */ + if (nexthdr == NEXTHDR_FRAGMENT) + hdrlen = 8; + else if (nexthdr == NEXTHDR_AUTH) + hdrlen = (hp->hdrlen+2)<<2; + else + hdrlen = ipv6_optlen(hp); + + /* AH -> evaluate */ + if (nexthdr == NEXTHDR_AUTH) { + temp |= MASK_AH; + break; + } + + + /* set the flag */ + switch (nexthdr) { + case NEXTHDR_HOP: + case NEXTHDR_ROUTING: + case NEXTHDR_FRAGMENT: + case NEXTHDR_AUTH: + case NEXTHDR_DEST: + break; + default: + DEBUGP("ipv6_ah match: unknown nextheader %u\n",nexthdr); + return 0; + } + + nexthdr = hp->nexthdr; + len -= hdrlen; + ptr += hdrlen; + if (ptr > skb->len) { + DEBUGP("ipv6_ah: new pointer too large! \n"); + break; + } + } + + /* AH header not found */ + if (temp != MASK_AH) + return 0; + + if (len < sizeof(struct ip_auth_hdr)){ + *hotdrop = 1; + return 0; + } + + ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah); + BUG_ON(ah == NULL); + + DEBUGP("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen); + DEBUGP("RES %04X ", ah->reserved); + DEBUGP("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi)); + + DEBUGP("IPv6 AH spi %02X ", + (spi_match(ahinfo->spis[0], ahinfo->spis[1], + ntohl(ah->spi), + !!(ahinfo->invflags & IP6T_AH_INV_SPI)))); + DEBUGP("len %02X %04X %02X ", + ahinfo->hdrlen, hdrlen, + (!ahinfo->hdrlen || + (ahinfo->hdrlen == hdrlen) ^ + !!(ahinfo->invflags & IP6T_AH_INV_LEN))); + DEBUGP("res %02X %04X %02X\n", + ahinfo->hdrres, ah->reserved, + !(ahinfo->hdrres && ah->reserved)); + + return (ah != NULL) + && + (spi_match(ahinfo->spis[0], ahinfo->spis[1], + ntohl(ah->spi), + !!(ahinfo->invflags & IP6T_AH_INV_SPI))) + && + (!ahinfo->hdrlen || + (ahinfo->hdrlen == hdrlen) ^ + !!(ahinfo->invflags & IP6T_AH_INV_LEN)) + && + !(ahinfo->hdrres && ah->reserved); +} + +/* Called when user tries to insert an entry of this type. */ +static int +checkentry(const char *tablename, + const struct ip6t_ip6 *ip, + void *matchinfo, + unsigned int matchinfosize, + unsigned int hook_mask) +{ + const struct ip6t_ah *ahinfo = matchinfo; + + if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_ah))) { + DEBUGP("ip6t_ah: matchsize %u != %u\n", + matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_ah))); + return 0; + } + if (ahinfo->invflags & ~IP6T_AH_INV_MASK) { + DEBUGP("ip6t_ah: unknown flags %X\n", ahinfo->invflags); + return 0; + } + return 1; +} + +static struct ip6t_match ah_match = { + .name = "ah", + .match = &match, + .checkentry = &checkentry, + .me = THIS_MODULE, +}; + +static int __init init(void) +{ + return ip6t_register_match(&ah_match); +} + +static void __exit cleanup(void) +{ + ip6t_unregister_match(&ah_match); +} + +module_init(init); +module_exit(cleanup); |