From 535a79f002c95b9d37ebded4f34c3b225c4c738d Mon Sep 17 00:00:00 2001 From: Duncan Roe Date: Fri, 20 Dec 2019 16:53:48 +1100 Subject: src: add mangle functions for IPv6, IPv6/TCP and IPv6/UDP Signed-off-by: Duncan Roe Signed-off-by: Pablo Neira Ayuso --- .../libnetfilter_queue/libnetfilter_queue_ipv6.h | 1 + .../libnetfilter_queue/libnetfilter_queue_tcp.h | 1 + .../libnetfilter_queue/libnetfilter_queue_udp.h | 1 + src/extra/ipv6.c | 29 ++++++++++++++++ src/extra/tcp.c | 40 ++++++++++++++++++++++ src/extra/udp.c | 39 +++++++++++++++++++++ 6 files changed, 111 insertions(+) diff --git a/include/libnetfilter_queue/libnetfilter_queue_ipv6.h b/include/libnetfilter_queue/libnetfilter_queue_ipv6.h index 93452ce..c0a7d37 100644 --- a/include/libnetfilter_queue/libnetfilter_queue_ipv6.h +++ b/include/libnetfilter_queue/libnetfilter_queue_ipv6.h @@ -6,6 +6,7 @@ struct ip6_hdr; struct ip6_hdr *nfq_ip6_get_hdr(struct pkt_buff *pktb); int nfq_ip6_set_transport_header(struct pkt_buff *pktb, struct ip6_hdr *iph, uint8_t target); +int nfq_ip6_mangle(struct pkt_buff *pktb, unsigned int dataoff,unsigned int match_offset, unsigned int match_len,const char *rep_buffer, unsigned int rep_len); int nfq_ip6_snprintf(char *buf, size_t size, const struct ip6_hdr *ip6h); #endif diff --git a/include/libnetfilter_queue/libnetfilter_queue_tcp.h b/include/libnetfilter_queue/libnetfilter_queue_tcp.h index c66dfb6..997d997 100644 --- a/include/libnetfilter_queue/libnetfilter_queue_tcp.h +++ b/include/libnetfilter_queue/libnetfilter_queue_tcp.h @@ -14,6 +14,7 @@ void nfq_tcp_compute_checksum_ipv4(struct tcphdr *tcph, struct iphdr *iph); void nfq_tcp_compute_checksum_ipv6(struct tcphdr *tcph, struct ip6_hdr *ip6h); int nfq_tcp_mangle_ipv4(struct pkt_buff *pkt, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len); +int nfq_tcp_mangle_ipv6(struct pkt_buff *pkt, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len); int nfq_tcp_snprintf(char *buf, size_t size, const struct tcphdr *tcp); diff --git a/include/libnetfilter_queue/libnetfilter_queue_udp.h b/include/libnetfilter_queue/libnetfilter_queue_udp.h index f4b6c49..f9fd609 100644 --- a/include/libnetfilter_queue/libnetfilter_queue_udp.h +++ b/include/libnetfilter_queue/libnetfilter_queue_udp.h @@ -11,6 +11,7 @@ void nfq_udp_compute_checksum_ipv4(struct udphdr *udph, struct iphdr *iph); void nfq_udp_compute_checksum_ipv6(struct udphdr *udph, struct ip6_hdr *ip6h); int nfq_udp_mangle_ipv4(struct pkt_buff *pkt, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len); +int nfq_udp_mangle_ipv6(struct pkt_buff *pktb, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len); int nfq_udp_snprintf(char *buf, size_t size, const struct udphdr *udp); diff --git a/src/extra/ipv6.c b/src/extra/ipv6.c index f685b3b..6e8820c 100644 --- a/src/extra/ipv6.c +++ b/src/extra/ipv6.c @@ -116,6 +116,35 @@ int nfq_ip6_set_transport_header(struct pkt_buff *pktb, struct ip6_hdr *ip6h, return cur ? 1 : 0; } +/** + * nfq_ip6_mangle - mangle IPv6 packet buffer + * \param pktb: Pointer to user-space network packet buffer + * \param dataoff: Offset to layer 4 header + * \param match_offset: Offset to content that you want to mangle + * \param match_len: Length of the existing content you want to mangle + * \param rep_buffer: Pointer to data you want to use to replace current content + * \param rep_len: Length of data you want to use to replace current content + * \returns 1 for success and 0 for failure. See pktb_mangle() for failure case + * \note This function updates the IPv6 length (if necessary) + */ +EXPORT_SYMBOL +int nfq_ip6_mangle(struct pkt_buff *pktb, unsigned int dataoff, + unsigned int match_offset, unsigned int match_len, + const char *rep_buffer, unsigned int rep_len) +{ + struct ip6_hdr *ip6h = (struct ip6_hdr *)pktb->network_header; + + if (!pktb_mangle(pktb, dataoff, match_offset, match_len, rep_buffer, + rep_len)) + return 0; + + /* Fix IPv6 hdr length information */ + ip6h->ip6_plen = + htons(pktb->tail - pktb->network_header - sizeof *ip6h); + + return 1; +} + /** * nfq_ip6_snprintf - print IPv6 header into one buffer in iptables LOG format * \param buf: Pointer to buffer that is used to print the object diff --git a/src/extra/tcp.c b/src/extra/tcp.c index 136d7ea..8119843 100644 --- a/src/extra/tcp.c +++ b/src/extra/tcp.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include "internal.h" @@ -206,6 +207,45 @@ int nfq_tcp_mangle_ipv4(struct pkt_buff *pkt, return 1; } +/** + * nfq_tcp_mangle_ipv6 - Mangle TCP/IPv6 packet buffer + * \param pktb: Pointer to network packet buffer + * \param match_offset: Offset from start of TCP data of content that you want + * to mangle + * \param match_len: Length of the existing content you want to mangle + * \param rep_buffer: Pointer to data you want to use to replace current content + * \param rep_len: Length of data you want to use to replace current content + * \returns 1 for success and 0 for failure. See pktb_mangle() for failure case + * \note This function updates the IPv6 length and recalculates the TCP + * checksum for you. + * \warning After changing the length of a TCP message, the application will + * need to mangle sequence numbers in both directions until another change + * puts them in sync again + */ +EXPORT_SYMBOL +int nfq_tcp_mangle_ipv6(struct pkt_buff *pktb, + unsigned int match_offset, unsigned int match_len, + const char *rep_buffer, unsigned int rep_len) +{ + struct ip6_hdr *ip6h; + struct tcphdr *tcph; + + ip6h = (struct ip6_hdr *)pktb->network_header; + tcph = (struct tcphdr *)(pktb->transport_header); + if (!tcph) + return 0; + + if (!nfq_ip6_mangle(pktb, + pktb->transport_header - pktb->network_header + + tcph->doff * 4, + match_offset, match_len, rep_buffer, rep_len)) + return 0; + + nfq_tcp_compute_checksum_ipv6(tcph, ip6h); + + return 1; +} + /** * @} */ diff --git a/src/extra/udp.c b/src/extra/udp.c index 34dbf2a..9eee1c7 100644 --- a/src/extra/udp.c +++ b/src/extra/udp.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include "internal.h" @@ -159,6 +160,44 @@ int nfq_udp_mangle_ipv4(struct pkt_buff *pktb, return 1; } +/** + * nfq_udp_mangle_ipv6 - Mangle UDP/IPv6 packet buffer + * \param pktb: Pointer to network packet buffer + * \param match_offset: Offset from start of UDP data of content that you want + * to mangle + * \param match_len: Length of the existing content you want to mangle + * \param rep_buffer: Pointer to data you want to use to replace current content + * \param rep_len: Length of data you want to use to replace current content + * \returns 1 for success and 0 for failure. See pktb_mangle() for failure case + * \note This function updates the IPv6 and UDP lengths and recalculates the UDP + * checksum for you. + */ +EXPORT_SYMBOL +int nfq_udp_mangle_ipv6(struct pkt_buff *pktb, + unsigned int match_offset, unsigned int match_len, + const char *rep_buffer, unsigned int rep_len) +{ + struct ip6_hdr *ip6h; + struct udphdr *udph; + + ip6h = (struct ip6_hdr *)pktb->network_header; + udph = (struct udphdr *)(pktb->transport_header); + if (!udph) + return 0; + + udph->len = htons(ntohs(udph->len) + rep_len - match_len); + + if (!nfq_ip6_mangle(pktb, + pktb->transport_header - pktb->network_header + + sizeof(struct udphdr), + match_offset, match_len, rep_buffer, rep_len)) + return 0; + + nfq_udp_compute_checksum_ipv6(udph, ip6h); + + return 1; +} + /** * nfq_pkt_snprintf_udp_hdr - print udp header into one buffer in a humnan * readable way -- cgit v1.2.3