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Subject[iptables] extensions: add support for 'srh' match
Date
This patch adds a new exetension to iptables to supprt 'srh' match
The implementation considers revision 7 of the SRH draft.
https://tools.ietf.org/html/draft-ietf-6man-segment-routing-header-07

Signed-off-by: Ahmed Abdelsalam <amsalam20@gmail.com>
---
extensions/libip6t_srh.c | 283 ++++++++++++++++++++++++++++++++
include/linux/netfilter_ipv6/ip6t_srh.h | 63 +++++++
2 files changed, 346 insertions(+)
create mode 100644 extensions/libip6t_srh.c
create mode 100644 include/linux/netfilter_ipv6/ip6t_srh.h

diff --git a/extensions/libip6t_srh.c b/extensions/libip6t_srh.c
new file mode 100644
index 0000000..fd92ba1
--- /dev/null
+++ b/extensions/libip6t_srh.c
@@ -0,0 +1,283 @@
+/**
+ * Segment Routing Header 'srh' match extension
+ *
+ * Author:
+ * Ahmed Abdelsalam <amsalam20@gmail.com>
+ */
+
+#include <stdio.h>
+#include <xtables.h>
+#include <linux/netfilter_ipv6/ip6t_srh.h>
+#include <string.h>
+
+/* srh command-line options */
+enum {
+ O_SRH_NEXTHDR,
+ O_SRH_LEN_EQ,
+ O_SRH_LEN_GT,
+ O_SRH_LEN_LT,
+ O_SRH_SEGS_EQ,
+ O_SRH_SEGS_GT,
+ O_SRH_SEGS_LT,
+ O_SRH_LAST_EQ,
+ O_SRH_LAST_GT,
+ O_SRH_LAST_LT,
+ O_SRH_TAG,
+};
+
+static void srh_help(void)
+{
+ printf(
+"srh match options:\n"
+"[!] --srh-next-hdr next-hdr Next Header value of SRH\n"
+"[!] --srh-len-eq hdr_len Hdr Ext Len value of SRH\n"
+"[!] --srh-len-gt hdr_len Hdr Ext Len value of SRH\n"
+"[!] --srh-len-lt hdr_len Hdr Ext Len value of SRH\n"
+"[!] --srh-segs-eq segs_left Segments Left value of SRH\n"
+"[!] --srh-segs-gt segs_left Segments Left value of SRH\n"
+"[!] --srh-segs-lt segs_left Segments Left value of SRH\n"
+"[!] --srh-last-eq last_entry Last Entry value of SRH\n"
+"[!] --srh-last-gt last_entry Last Entry value of SRH\n"
+"[!] --srh-last-lt last_entry Last Entry value of SRH\n"
+"[!] --srh-tag tag Tag value of SRH\n");
+}
+
+#define s struct ip6t_srh
+static const struct xt_option_entry srh_opts[] = {
+ { .name = "srh-next-hdr", .id = O_SRH_NEXTHDR, .type = XTTYPE_UINT8,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, next_hdr)},
+ { .name = "srh-len-eq", .id = O_SRH_LEN_EQ, .type = XTTYPE_UINT8,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, hdr_len)},
+ { .name = "srh-len-gt", .id = O_SRH_LEN_GT, .type = XTTYPE_UINT8,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, hdr_len)},
+ { .name = "srh-len-lt", .id = O_SRH_LEN_LT, .type = XTTYPE_UINT8,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, hdr_len)},
+ { .name = "srh-segs-eq", .id = O_SRH_SEGS_EQ, .type = XTTYPE_UINT8,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, segs_left)},
+ { .name = "srh-segs-gt", .id = O_SRH_SEGS_GT, .type = XTTYPE_UINT8,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, segs_left)},
+ { .name = "srh-segs-lt", .id = O_SRH_SEGS_LT, .type = XTTYPE_UINT8,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, segs_left)},
+ { .name = "srh-last-eq", .id = O_SRH_LAST_EQ, .type = XTTYPE_UINT8,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, last_entry)},
+ { .name = "srh-last-gt", .id = O_SRH_LAST_GT, .type = XTTYPE_UINT8,
+ flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, last_entry)},
+ { .name = "srh-last-lt", .id = O_SRH_LAST_LT, .type = XTTYPE_UINT8,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, last_entry)},
+ { .name = "srh-tag", .id = O_SRH_TAG, .type = XTTYPE_UINT16,
+ .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, tag)},
+ { }
+};
+#undef s
+
+static void srh_init(struct xt_entry_match *m)
+{
+ struct ip6t_srh *srhinfo = (void *)m->data;
+
+ srhinfo->mt_flags = 0;
+ srhinfo->mt_invflags = 0;
+}
+
+static void srh_parse(struct xt_option_call *cb)
+{
+ struct ip6t_srh *srhinfo = cb->data;
+
+ xtables_option_parse(cb);
+ switch (cb->entry->id) {
+ case O_SRH_NEXTHDR:
+ srhinfo->mt_flags |= IP6T_SRH_NEXTHDR;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_NEXTHDR;
+ break;
+ case O_SRH_LEN_EQ:
+ srhinfo->mt_flags |= IP6T_SRH_LEN_EQ;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_LEN_EQ;
+ break;
+ case O_SRH_LEN_GT:
+ srhinfo->mt_flags |= IP6T_SRH_LEN_GT;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_LEN_GT;
+ break;
+ case O_SRH_LEN_LT:
+ srhinfo->mt_flags |= IP6T_SRH_LEN_LT;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_LEN_LT;
+ break;
+ case O_SRH_SEGS_EQ:
+ srhinfo->mt_flags |= IP6T_SRH_SEGS_EQ;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_SEGS_EQ;
+ break;
+ case O_SRH_SEGS_GT:
+ srhinfo->mt_flags |= IP6T_SRH_SEGS_GT;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_SEGS_GT;
+ break;
+ case O_SRH_SEGS_LT:
+ srhinfo->mt_flags |= IP6T_SRH_SEGS_LT;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_SEGS_LT;
+ break;
+ case O_SRH_LAST_EQ:
+ srhinfo->mt_flags |= IP6T_SRH_LAST_EQ;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_LAST_EQ;
+ break;
+ case O_SRH_LAST_GT:
+ srhinfo->mt_flags |= IP6T_SRH_LAST_GT;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_LAST_GT;
+ break;
+ case O_SRH_LAST_LT:
+ srhinfo->mt_flags |= IP6T_SRH_LAST_LT;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_LAST_LT;
+ break;
+ case O_SRH_TAG:
+ srhinfo->mt_flags |= IP6T_SRH_TAG;
+ if (cb->invert)
+ srhinfo->mt_invflags |= IP6T_SRH_INV_TAG;
+ break;
+ }
+}
+
+static const char *pinv(bool invert)
+{
+ const char *inv = invert ? "!" : " ";
+ return inv;
+}
+
+static void srh_print(const void *ip, const struct xt_entry_match *match,
+ int numeric)
+{
+ const struct ip6t_srh *srhinfo = (struct ip6t_srh *)match->data;
+
+ printf(" srh ");
+
+ if (srhinfo->mt_flags & IP6T_SRH_NEXTHDR)
+ printf("next-hdr %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_NEXTHDR),
+ srhinfo->next_hdr);
+
+ if (srhinfo->mt_flags & IP6T_SRH_LEN_EQ)
+ printf("hdr-len %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LEN_EQ),
+ srhinfo->hdr_len);
+ if (srhinfo->mt_flags & IP6T_SRH_LEN_GT)
+ printf("hdr-len %s>%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LEN_GT),
+ srhinfo->hdr_len);
+ if (srhinfo->mt_flags & IP6T_SRH_LEN_LT)
+ printf("hdr-len %s<%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LEN_LT),
+ srhinfo->hdr_len);
+
+ if (srhinfo->mt_flags & IP6T_SRH_SEGS_EQ)
+ printf("segs-left %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_SEGS_EQ),
+ srhinfo->segs_left);
+ if (srhinfo->mt_flags & IP6T_SRH_SEGS_GT)
+ printf("segs-left %s>%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_SEGS_GT),
+ srhinfo->segs_left);
+ if (srhinfo->mt_flags & IP6T_SRH_SEGS_LT)
+ printf("segs-left %s<%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_SEGS_LT),
+ srhinfo->segs_left);
+
+ if (srhinfo->mt_flags & IP6T_SRH_LAST_EQ)
+ printf("last-entry %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LAST_EQ),
+ srhinfo->last_entry);
+ if (srhinfo->mt_flags & IP6T_SRH_LAST_GT)
+ printf("last-entry %s>%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LAST_GT),
+ srhinfo->last_entry);
+ if (srhinfo->mt_flags & IP6T_SRH_LAST_LT)
+ printf("last-entry %s<%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LAST_LT),
+ srhinfo->last_entry);
+
+ if (srhinfo->mt_flags & IP6T_SRH_TAG)
+ printf("tag %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_TAG),
+ srhinfo->tag);
+
+}
+
+static void srh_save(const void *ip, const struct xt_entry_match *match)
+{
+ const struct ip6t_srh *srhinfo = (struct ip6t_srh *)match->data;
+
+ printf(" srh ");
+
+ if (srhinfo->mt_flags & IP6T_SRH_NEXTHDR)
+ printf("next-hdr %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_NEXTHDR),
+ srhinfo->next_hdr);
+
+ if (srhinfo->mt_flags & IP6T_SRH_LEN_EQ)
+ printf("hdr-len %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LEN_EQ),
+ srhinfo->hdr_len);
+ if (srhinfo->mt_flags & IP6T_SRH_LEN_GT)
+ printf("hdr-len %s>%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LEN_GT),
+ srhinfo->hdr_len);
+ if (srhinfo->mt_flags & IP6T_SRH_LEN_LT)
+ printf("hdr-len %s<%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LEN_LT),
+ srhinfo->hdr_len);
+
+ if (srhinfo->mt_flags & IP6T_SRH_SEGS_EQ)
+ printf("segs-left %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_SEGS_EQ),
+ srhinfo->segs_left);
+ if (srhinfo->mt_flags & IP6T_SRH_SEGS_GT)
+ printf("segs-left %s>%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_SEGS_GT),
+ srhinfo->segs_left);
+ if (srhinfo->mt_flags & IP6T_SRH_SEGS_LT)
+ printf("segs-left %s<%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_SEGS_LT),
+ srhinfo->segs_left);
+
+ if (srhinfo->mt_flags & IP6T_SRH_LAST_EQ)
+ printf("last-entry %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LAST_EQ),
+ srhinfo->last_entry);
+ if (srhinfo->mt_flags & IP6T_SRH_LAST_GT)
+ printf("last-entry %s>%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LAST_GT),
+ srhinfo->last_entry);
+ if (srhinfo->mt_flags & IP6T_SRH_LAST_LT)
+ printf("last-entry %s<%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_LAST_LT),
+ srhinfo->last_entry);
+
+ if (srhinfo->mt_flags & IP6T_SRH_TAG)
+ printf("tag %s=%d ",
+ pinv(srhinfo->mt_invflags & IP6T_SRH_INV_TAG),
+ srhinfo->tag);
+}
+
+static struct xtables_match srh_mt6_reg = {
+ .name = "srh",
+ .version = XTABLES_VERSION,
+ .family = NFPROTO_IPV6,
+ .size = XT_ALIGN(sizeof(struct ip6t_srh)),
+ .userspacesize = XT_ALIGN(sizeof(struct ip6t_srh)),
+ .help = srh_help,
+ .init = srh_init,
+ .print = srh_print,
+ .save = srh_save,
+ .x6_parse = srh_parse,
+ .x6_options = srh_opts,
+};
+
+void
+_init(void)
+{
+ xtables_register_match(&srh_mt6_reg);
+}
diff --git a/include/linux/netfilter_ipv6/ip6t_srh.h b/include/linux/netfilter_ipv6/ip6t_srh.h
new file mode 100644
index 0000000..bc27197
--- /dev/null
+++ b/include/linux/netfilter_ipv6/ip6t_srh.h
@@ -0,0 +1,63 @@
+/**
+ * Definitions for Segment Routing Header 'srh' match
+ *
+ * Author:
+ * Ahmed Abdelsalam <amsalam20@gmail.com>
+ */
+
+#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
+
+/**
+ * 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*/
--
2.1.4
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