This patch is part of the userspace changes needed for the "secmark" match
in iptables.
Signed-off-by: Mr Dash Four <mr.dash.four@xxxxxxxxxxxxxx>
---
extensions/libxt_secmark.c | 100 ++++++++++++++++++++++++++++++++++
extensions/libxt_secmark.man | 22 ++++++++
include/linux/netfilter/xt_secmark.h | 24 ++++++++
3 files changed, 146 insertions(+)
create mode 100644 extensions/libxt_secmark.c
create mode 100644 extensions/libxt_secmark.man
create mode 100644 include/linux/netfilter/xt_secmark.h
diff --git a/extensions/libxt_secmark.c b/extensions/libxt_secmark.c
new file mode 100644
index 0000000..92ecc6b
--- /dev/null
+++ b/extensions/libxt_secmark.c
@@ -0,0 +1,100 @@
+/*
+ * Shared library add-on to iptables to add secmark match support.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 (or
+ * any later at your option) as published by the Free Software Foundation.
+ */
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <getopt.h>
+#include <xtables.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_secmark.h>
+
+#define PFX "secmark match: "
+
+enum {
+ O_SELCTX = 0,
+};
+
+#define s struct xt_secmark_match_info
+static const struct xt_option_entry secmark_opts[] = {
+ {.name = "selctx", .id = O_SELCTX, .type = XTTYPE_STRING,
+ .flags = XTOPT_MAND|XTOPT_PUT, XTOPT_POINTER(s, secctx)},
+ XTOPT_TABLEEND,
+};
+#undef s
+
+static void secmark_help(void)
+{
+ printf("secmark match options:\n"
+ " --selctx STRING SELinux security context\n");
+}
+
+static void secmark_parse(struct xt_option_call *cb)
+{
+ struct xt_secmark_match_info *info = cb->data;
+
+ xtables_option_parse(cb);
+ switch (cb->entry->id) {
+ case O_SELCTX:
+ if (strchr(cb->arg, '\n') != NULL)
+ xtables_error(PARAMETER_PROBLEM, PFX
+ "new lines not allowed in --selctx");
+ info->mode = SECMARK_MODE_SEL;
+ break;
+ }
+}
+
+static void
+secmark_print_selctx(const struct xt_secmark_match_info *info, char *str)
+{
+ switch (info->mode) {
+ case SECMARK_MODE_SEL:
+ printf(" %sselctx %s", str, info->secctx);
+ break;
+
+ default:
+ xtables_error(OTHER_PROBLEM, PFX "invalid mode %hhu\n", info->mode);
+ }
+}
+
+static void secmark_print(const void *ip, const struct xt_entry_match *match,
+ int numeric)
+{
+ const struct xt_secmark_match_info *info =
+ (struct xt_secmark_match_info *)match->data;
+
+ secmark_print_selctx(info, "");
+}
+
+static void secmark_save(const void *ip, const struct xt_entry_match *match)
+{
+ const struct xt_secmark_match_info *info =
+ (struct xt_secmark_match_info *)match->data;
+
+ secmark_print_selctx(info, "--");
+}
+
+static struct xtables_match secmark_match = {
+ .family = NFPROTO_UNSPEC,
+ .name = "secmark",
+ .version = XTABLES_VERSION,
+ .revision = 0,
+ .size = XT_ALIGN(sizeof(struct xt_secmark_match_info)),
+ .userspacesize = XT_ALIGN(sizeof(struct xt_secmark_match_info)),
+ .help = secmark_help,
+ .print = secmark_print,
+ .save = secmark_save,
+ .x6_parse = secmark_parse,
+ .x6_options = secmark_opts,
+};
+
+void _init(void)
+{
+ xtables_register_match(&secmark_match);
+}
diff --git a/extensions/libxt_secmark.man b/extensions/libxt_secmark.man
new file mode 100644
index 0000000..b38e32c
--- /dev/null
+++ b/extensions/libxt_secmark.man
@@ -0,0 +1,22 @@
+The secmark match is used to match the security mark value
+associated with a packet.
+.PP
+Only one option is available with this match which needs
+to be specified:
+.TP
+\fB\-\-selctx\fP \fIselctx\fP
+This option selects the SELinux security context (\fBselctx\fP) to
+be used for packet matching. This security context needs to have already
+been assigned to a packet by using the \fBSECMARK\fP target.
+.PP
+For this extension to be used, the appropriate SELinux support needs
+to be installed and present in the Linux kernel.
+.PP
+Examples:
+.IP
+iptables \-I INPUT \-p icmp \-\-icmp-type 3 \-m secmark \-\-selctx
+system_u:object_r:dns_packet_t:s0 \-j ACCEPT
+.IP
+iptables \-I OUTPUT \-m secmark \-\-selctx
+system_u:object_r:ssh_packet_t:s0 \-j DROP
+
diff --git a/include/linux/netfilter/xt_secmark.h b/include/linux/netfilter/xt_secmark.h
new file mode 100644
index 0000000..c74a35d
--- /dev/null
+++ b/include/linux/netfilter/xt_secmark.h
@@ -0,0 +1,24 @@
+#ifndef _XT_SECMARK_MATCH_H
+#define _XT_SECMARK_MATCH_H
+
+#include <linux/types.h>
+
+/*
+ * Header file for iptables xt_secmark match
+ *
+ * This is intended for use by various security subsystems (but not
+ * at the same time).
+ *
+ * 'mode' refers to the specific security subsystem which the
+ * packets are being marked for.
+ */
+#define SECMARK_MODE_SEL 0x01 /* SELinux */
+#define SECMARK_SECCTX_MAX 256
+
+struct xt_secmark_match_info {
+ __u8 mode;
+ __u32 secid;
+ char secctx[SECMARK_SECCTX_MAX];
+};
+
+#endif /* _XT_SECMARK_MATCH_H */
--
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