iptables: add libxt_cgroup frontend

This patch adds the user space extension/frontend for process matching
based on cgroups from the kernel patch entitled "netfilter: xtables:
lightweight process control group matching".

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/extensions/libxt_cgroup.c b/extensions/libxt_cgroup.c
new file mode 100644 (file)
index 0000000..e304e33
--- /dev/null
+++ b/extensions/libxt_cgroup.c
@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <xtables.h>
+#include <linux/netfilter/xt_cgroup.h>
+
+enum {
+       O_CGROUP = 0,
+};
+
+static void cgroup_help(void)
+{
+       printf(
+"cgroup match options:\n"
+"[!] --cgroup fwid  Match cgroup fwid\n");
+}
+
+static const struct xt_option_entry cgroup_opts[] = {
+       {
+               .name = "cgroup",
+               .id = O_CGROUP,
+               .type = XTTYPE_UINT32,
+               .flags = XTOPT_INVERT | XTOPT_MAND | XTOPT_PUT,
+               XTOPT_POINTER(struct xt_cgroup_info, id)
+       },
+       XTOPT_TABLEEND,
+};
+
+static void cgroup_parse(struct xt_option_call *cb)
+{
+       struct xt_cgroup_info *cgroupinfo = cb->data;
+
+       xtables_option_parse(cb);
+       if (cb->invert)
+               cgroupinfo->invert = true;
+}
+
+static void
+cgroup_print(const void *ip, const struct xt_entry_match *match, int numeric)
+{
+       const struct xt_cgroup_info *info = (void *) match->data;
+
+       printf(" cgroup %s%u", info->invert ? "! ":"", info->id);
+}
+
+static void cgroup_save(const void *ip, const struct xt_entry_match *match)
+{
+       const struct xt_cgroup_info *info = (void *) match->data;
+
+       printf("%s --cgroup %u", info->invert ? " !" : "", info->id);
+}
+
+static struct xtables_match cgroup_match = {
+       .family         = NFPROTO_UNSPEC,
+       .name           = "cgroup",
+       .version        = XTABLES_VERSION,
+       .size           = XT_ALIGN(sizeof(struct xt_cgroup_info)),
+       .userspacesize  = XT_ALIGN(sizeof(struct xt_cgroup_info)),
+       .help           = cgroup_help,
+       .print          = cgroup_print,
+       .save           = cgroup_save,
+       .x6_parse       = cgroup_parse,
+       .x6_options     = cgroup_opts,
+};
+
+void _init(void)
+{
+       xtables_register_match(&cgroup_match);
+}

diff --git a/extensions/libxt_cgroup.man b/extensions/libxt_cgroup.man
new file mode 100644 (file)
index 0000000..456a031
--- /dev/null
+++ b/extensions/libxt_cgroup.man
@@ -0,0 +1,15 @@
+.TP
+[\fB!\fP] \fB\-\-cgroup\fP \fIfwid\fP
+Match corresponding cgroup for this packet.
+
+Can be used to assign particular firewall policies for aggregated
+task/jobs on the system. This allows for more fine-grained firewall
+policies that only match for a subset of the system's processes.
+fwid is the maker set through the net_cls cgroup's id.
+.PP
+Example:
+.PP
+iptables \-A OUTPUT \-p tcp \-\-sport 80 \-m cgroup ! \-\-cgroup 1
+\-j DROP
+.PP
+Available since Linux 3.14.

diff --git a/include/linux/netfilter/xt_cgroup.h b/include/linux/netfilter/xt_cgroup.h
new file mode 100644 (file)
index 0000000..943d3a0
--- /dev/null
+++ b/include/linux/netfilter/xt_cgroup.h
@@ -0,0 +1,11 @@
+#ifndef _XT_CGROUP_H
+#define _XT_CGROUP_H
+
+#include <linux/types.h>
+
+struct xt_cgroup_info {
+       __u32 id;
+       __u32 invert;
+};
+
+#endif /* _XT_CGROUP_H */