Hi Ahmed, On Fri, Dec 29, 2017 at 12:07:52PM +0100, Ahmed Abdelsalam wrote: > It allows matching packets based on Segment Routing Header > (SRH) information. > The implementation considers revision 7 of the SRH draft. > https://tools.ietf.org/html/draft-ietf-6man-segment-routing-header-07 > > Currently supported match options include: > (1) Next Header > (2) Hdr Ext Len > (3) Segments Left > (4) Last Entry > (5) Tag value of SRH > > Signed-off-by: Ahmed Abdelsalam <amsalam20@xxxxxxxxx> > --- > include/uapi/linux/netfilter_ipv6/ip6t_srh.h | 63 ++++++++++ > net/ipv6/netfilter/Kconfig | 9 ++ > net/ipv6/netfilter/Makefile | 1 + > net/ipv6/netfilter/ip6t_srh.c | 165 +++++++++++++++++++++++++++ > 4 files changed, 238 insertions(+) > create mode 100644 include/uapi/linux/netfilter_ipv6/ip6t_srh.h > create mode 100644 net/ipv6/netfilter/ip6t_srh.c > > diff --git a/include/uapi/linux/netfilter_ipv6/ip6t_srh.h b/include/uapi/linux/netfilter_ipv6/ip6t_srh.h > new file mode 100644 > index 0000000..1b5dbd8 > --- /dev/null > +++ b/include/uapi/linux/netfilter_ipv6/ip6t_srh.h > @@ -0,0 +1,63 @@ > +/** > + * Definitions for Segment Routing Header 'srh' match > + * > + * Author: > + * Ahmed Abdelsalam <amsalam20@xxxxxxxxx> > + */ Please, add this in SPDX format instead. See include/uapi/linux/netfilter/xt_owner.h for instance. > +#ifndef _IP6T_SRH_H > +#define _IP6T_SRH_H > + > +#include <linux/types.h> > +#include <linux/netfilter.h> > + > +/* Values for "mt_flags" field in struct ip6t_srh */ > +#define IP6T_SRH_NEXTHDR 0x0001 > +#define IP6T_SRH_LEN_EQ 0x0002 > +#define IP6T_SRH_LEN_GT 0x0004 > +#define IP6T_SRH_LEN_LT 0x0008 > +#define IP6T_SRH_SEGS_EQ 0x0010 > +#define IP6T_SRH_SEGS_GT 0x0020 > +#define IP6T_SRH_SEGS_LT 0x0040 > +#define IP6T_SRH_LAST_EQ 0x0080 > +#define IP6T_SRH_LAST_GT 0x0100 > +#define IP6T_SRH_LAST_LT 0x0200 > +#define IP6T_SRH_TAG 0x0400 > +#define IP6T_SRH_MASK 0x07FF > + > +/* Values for "mt_invflags" field in struct ip6t_srh */ > +#define IP6T_SRH_INV_NEXTHDR 0x0001 > +#define IP6T_SRH_INV_LEN_EQ 0x0002 > +#define IP6T_SRH_INV_LEN_GT 0x0004 > +#define IP6T_SRH_INV_LEN_LT 0x0008 > +#define IP6T_SRH_INV_SEGS_EQ 0x0010 > +#define IP6T_SRH_INV_SEGS_GT 0x0020 > +#define IP6T_SRH_INV_SEGS_LT 0x0040 > +#define IP6T_SRH_INV_LAST_EQ 0x0080 > +#define IP6T_SRH_INV_LAST_GT 0x0100 > +#define IP6T_SRH_INV_LAST_LT 0x0200 > +#define IP6T_SRH_INV_TAG 0x0400 > +#define IP6T_SRH_INV_MASK 0x07FF Looking at all these EQ, GT, LT... I think this should be very easy to implement in nf_tables with no kernel changes. You only need to add the protocol definition to: nftables/src/exthdr.c Would you have a look into this? This would be very much appreciated to we keep nftables in sync with what we have in iptables. > + > +/** > + * struct ip6t_srh - SRH match options > + * @ next_hdr: Next header field of SRH > + * @ hdr_len: Extension header length field of SRH > + * @ segs_left: Segments left field of SRH > + * @ last_entry: Last entry field of SRH > + * @ tag: Tag field of SRH > + * @ mt_flags: match options > + * @ mt_invflags: Invert the sense of match options > + */ > + > +struct ip6t_srh { > + __u8 next_hdr; > + __u8 hdr_len; > + __u8 segs_left; > + __u8 last_entry; > + __u16 tag; > + __u16 mt_flags; > + __u16 mt_invflags; > +}; > + > +#endif /*_IP6T_SRH_H*/ > diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig > index 6acb2ee..e1818eb 100644 > --- a/net/ipv6/netfilter/Kconfig > +++ b/net/ipv6/netfilter/Kconfig > @@ -232,6 +232,15 @@ config IP6_NF_MATCH_RT > > To compile it as a module, choose M here. If unsure, say N. > > +config IP6_NF_MATCH_SRH > + tristate '"srh" Segment Routing header match support' > + depends on NETFILTER_ADVANCED > + help > + srh matching allows you to match packets based on the segment > + routing header of the packet. > + > + To compile it as a module, choose M here. If unsure, say N. > + > # The targets > config IP6_NF_TARGET_HL > tristate '"HL" hoplimit target support' > diff --git a/net/ipv6/netfilter/Makefile b/net/ipv6/netfilter/Makefile > index c6ee0cd..e0d51a9 100644 > --- a/net/ipv6/netfilter/Makefile > +++ b/net/ipv6/netfilter/Makefile > @@ -54,6 +54,7 @@ obj-$(CONFIG_IP6_NF_MATCH_MH) += ip6t_mh.o > obj-$(CONFIG_IP6_NF_MATCH_OPTS) += ip6t_hbh.o > obj-$(CONFIG_IP6_NF_MATCH_RPFILTER) += ip6t_rpfilter.o > obj-$(CONFIG_IP6_NF_MATCH_RT) += ip6t_rt.o > +obj-$(CONFIG_IP6_NF_MATCH_SRH) += ip6t_srh.o > > # targets > obj-$(CONFIG_IP6_NF_TARGET_MASQUERADE) += ip6t_MASQUERADE.o > diff --git a/net/ipv6/netfilter/ip6t_srh.c b/net/ipv6/netfilter/ip6t_srh.c > new file mode 100644 > index 0000000..75e41dc9 > --- /dev/null > +++ b/net/ipv6/netfilter/ip6t_srh.c > @@ -0,0 +1,165 @@ > +/* > + * Kernel module to match Segment Routing Header (SRH) parameters. > + * > + * Author: > + * Ahmed Abdelsalam <amsalam20@xxxxxxxxx> > + * > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License > + * as published by the Free Software Foundation; either version 2 > + * of the License, or (at your option) any later version. > + */ > + > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > +#include <linux/module.h> > +#include <linux/skbuff.h> > +#include <linux/ipv6.h> > +#include <linux/types.h> > +#include <net/ipv6.h> > +#include <net/seg6.h> > + > +#include <linux/netfilter/x_tables.h> > +#include <linux/netfilter_ipv6/ip6t_srh.h> > +#include <linux/netfilter_ipv6/ip6_tables.h> > + > +MODULE_LICENSE("GPL"); > +MODULE_DESCRIPTION("Xtables: IPv6 Segment Routing Header match"); > +MODULE_AUTHOR("Ahmed Abdelsalam <amsalam20@xxxxxxxxx>"); Not a deal breaker, but modern code usually places these MODULE_* lines at the end of the file. > + > +/* Test a struct->mt_invflags and a boolean for inequality */ > +#define NF_SRH_INVF(ptr, flag, boolean) \ > + ((boolean) ^ !!((ptr)->mt_invflags & (flag))) > + > +static bool srh_mt6(const struct sk_buff *skb, struct xt_action_param *par) > +{ > + const struct ip6t_srh *srhinfo = par->matchinfo; > + struct ipv6_sr_hdr *srh; > + struct ipv6_sr_hdr _srh; > + int hdrlen, srhoff = 0; > + > + if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, NULL) < 0) > + return false; > + > + srh = skb_header_pointer(skb, srhoff, sizeof(_srh), &_srh); > + Remove unnecessary line break. > + if (!srh) > + return false; > + > + hdrlen = ipv6_optlen(srh); > + if (skb->len - srhoff < hdrlen) > + return false; > + > + if (srh->type != IPV6_SRCRT_TYPE_4) > + return false; > + > + if (srh->segments_left > srh->first_segment) > + return false; > + > + /* Next Header matching */ > + if (srhinfo->mt_flags & IP6T_SRH_NEXTHDR) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_NEXTHDR, > + !(srh->nexthdr == srhinfo->next_hdr))) > + return false; > + > + /* Header Extension Length matching */ > + if (srhinfo->mt_flags & IP6T_SRH_LEN_EQ) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_EQ, > + !(srh->hdrlen == srhinfo->hdr_len))) > + return false; > + > + if (srhinfo->mt_flags & IP6T_SRH_LEN_GT) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_GT, > + !(srh->hdrlen > srhinfo->hdr_len))) > + return false; > + > + if (srhinfo->mt_flags & IP6T_SRH_LEN_LT) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LEN_LT, > + !(srh->hdrlen < srhinfo->hdr_len))) > + return false; > + > + /* Segments Left matching */ > + if (srhinfo->mt_flags & IP6T_SRH_SEGS_EQ) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_EQ, > + !(srh->segments_left == srhinfo->segs_left))) > + return false; > + > + if (srhinfo->mt_flags & IP6T_SRH_SEGS_GT) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_GT, > + !(srh->segments_left > srhinfo->segs_left))) > + return false; > + > + if (srhinfo->mt_flags & IP6T_SRH_SEGS_LT) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_SEGS_LT, > + !(srh->segments_left < srhinfo->segs_left))) > + return false; > + > + /** > + * Last Entry matching > + * Last_Entry field was introduced in revision 6 of the SRH draft. > + * It was called First_Segment in the previous revision > + */ > + if (srhinfo->mt_flags & IP6T_SRH_LAST_EQ) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_EQ, > + !(srh->first_segment == srhinfo->last_entry))) > + return false; > + > + if (srhinfo->mt_flags & IP6T_SRH_LAST_GT) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_GT, > + !(srh->first_segment > srhinfo->last_entry))) > + return false; > + > + if (srhinfo->mt_flags & IP6T_SRH_LAST_LT) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LAST_LT, > + !(srh->first_segment < srhinfo->last_entry))) > + return false; > + > + /** > + * Tag matchig > + * Tag field was introduced in revision 6 of the SRH draft. > + */ > + if (srhinfo->mt_flags & IP6T_SRH_TAG) > + if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_TAG, > + !(srh->tag == srhinfo->tag))) > + return false; > + return true; > +} > + > +static int srh_mt6_check(const struct xt_mtchk_param *par) > +{ > + const struct ip6t_srh *srhinfo = par->matchinfo; > + > + if (srhinfo->mt_flags & ~IP6T_SRH_MASK) { > + pr_debug("unknown srh match flags %X\n", srhinfo->mt_flags); Better call pr_err() here. I know we don't do this in other extensions, but we should not use pr_debug() for this. ip6tables explicit refers to 'dmesg' when -EINVAL is returned. Thanks. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
