This patch implements xt_cgroup2 which matches cgroup2 membership of
the associated socket. The match is recursive and invertible.
For rationales on introducing another cgroup based match, please refer
to a preceding commit "sock, cgroup: add sock->sk_cgroup".
v2: Included linux/limits.h from xt_cgroup2.h for PATH_MAX. Added
explicit alignment to the priv field. Both suggested by Jan.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx>
CC: Neil Horman <nhorman@xxxxxxxxxxxxx>
Cc: Jan Engelhardt <jengelh@xxxxxxx>
---
include/uapi/linux/netfilter/xt_cgroup2.h | 15 ++++++
net/netfilter/Kconfig | 10 ++++
net/netfilter/Makefile | 1 +
net/netfilter/xt_cgroup2.c | 78 +++++++++++++++++++++++++++++++
4 files changed, 104 insertions(+)
create mode 100644 include/uapi/linux/netfilter/xt_cgroup2.h
create mode 100644 net/netfilter/xt_cgroup2.c
diff --git a/include/uapi/linux/netfilter/xt_cgroup2.h b/include/uapi/linux/netfilter/xt_cgroup2.h
new file mode 100644
index 0000000..ea51335
--- /dev/null
+++ b/include/uapi/linux/netfilter/xt_cgroup2.h
@@ -0,0 +1,15 @@
+#ifndef _XT_CGROUP2_H
+#define _XT_CGROUP2_H
+
+#include <linux/types.h>
+#include <linux/limits.h>
+
+struct xt_cgroup2_info {
+ char path[PATH_MAX];
+ __u8 invert;
+
+ /* kernel internal data */
+ void *priv __attribute__((aligned(8)));
+};
+
+#endif /* _XT_CGROUP2_H */
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index e22349e..5fd12dd 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -974,6 +974,16 @@ config NETFILTER_XT_MATCH_BPF
To compile it as a module, choose M here. If unsure, say N.
+config NETFILTER_XT_MATCH_CGROUP2
+ tristate '"cgroup2" match support'
+ depends on NETFILTER_ADVANCED
+ depends on CGROUPS
+ select SOCK_CGROUP_DATA
+ help
+ cgroup2 matching allows you to match locally generated and
+ early demuxed packets based on the v2 cgroup the socket is
+ associated with on creation.
+
config NETFILTER_XT_MATCH_CGROUP
tristate '"control group" match support'
depends on NETFILTER_ADVANCED
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 7638c36..86cee05 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -152,6 +152,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_MULTIPORT) += xt_multiport.o
obj-$(CONFIG_NETFILTER_XT_MATCH_NFACCT) += xt_nfacct.o
obj-$(CONFIG_NETFILTER_XT_MATCH_OSF) += xt_osf.o
obj-$(CONFIG_NETFILTER_XT_MATCH_OWNER) += xt_owner.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_CGROUP2) += xt_cgroup2.o
obj-$(CONFIG_NETFILTER_XT_MATCH_CGROUP) += xt_cgroup.o
obj-$(CONFIG_NETFILTER_XT_MATCH_PHYSDEV) += xt_physdev.o
obj-$(CONFIG_NETFILTER_XT_MATCH_PKTTYPE) += xt_pkttype.o
diff --git a/net/netfilter/xt_cgroup2.c b/net/netfilter/xt_cgroup2.c
new file mode 100644
index 0000000..39884b3
--- /dev/null
+++ b/net/netfilter/xt_cgroup2.c
@@ -0,0 +1,78 @@
+#include <linux/skbuff.h>
+#include <linux/module.h>
+#include <linux/cgroup.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_cgroup2.h>
+#include <net/sock.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Tejun Heo <tj@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Xtables: cgroup2 socket ownership matching");
+MODULE_ALIAS("ipt_cgroup2");
+MODULE_ALIAS("ip6t_cgroup2");
+
+static int cgroup2_mt_check(const struct xt_mtchk_param *par)
+{
+ struct xt_cgroup2_info *info = par->matchinfo;
+ struct cgroup *cgrp;
+
+ if (info->invert & ~1)
+ return -EINVAL;
+
+ cgrp = cgroup_get_from_path(info->path);
+ if (IS_ERR(cgrp)) {
+ pr_info("xt_cgroup2: invalid path, errno=%ld\n", PTR_ERR(cgrp));
+ return -EINVAL;
+ }
+ info->priv = cgrp;
+
+ return 0;
+}
+
+static bool cgroup2_mt(const struct sk_buff *skb, struct xt_action_param *par)
+{
+ const struct xt_cgroup2_info *info = par->matchinfo;
+ struct cgroup *ancestor = info->priv;
+ struct cgroup *cgrp;
+
+ if (!skb->sk || !sk_fullsock(skb->sk))
+ return false;
+
+ cgrp = sock_cgroup_ptr(&skb->sk->sk_cgrp_data);
+
+ return cgroup_is_descendant(cgrp, ancestor) ^ info->invert;
+}
+
+static void cgroup2_mt_destroy(const struct xt_mtdtor_param *par)
+{
+ struct xt_cgroup2_info *info = par->matchinfo;
+
+ cgroup_put(info->priv);
+}
+
+static struct xt_match cgroup2_mt_reg __read_mostly = {
+ .name = "cgroup2",
+ .revision = 0,
+ .family = NFPROTO_UNSPEC,
+ .checkentry = cgroup2_mt_check,
+ .match = cgroup2_mt,
+ .matchsize = sizeof(struct xt_cgroup2_info),
+ .destroy = cgroup2_mt_destroy,
+ .me = THIS_MODULE,
+ .hooks = (1 << NF_INET_LOCAL_OUT) |
+ (1 << NF_INET_POST_ROUTING) |
+ (1 << NF_INET_LOCAL_IN),
+};
+
+static int __init cgroup2_mt_init(void)
+{
+ return xt_register_match(&cgroup2_mt_reg);
+}
+
+static void __exit cgroup2_mt_exit(void)
+{
+ xt_unregister_match(&cgroup2_mt_reg);
+}
+
+module_init(cgroup2_mt_init);
+module_exit(cgroup2_mt_exit);
--
2.5.0
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