Re: [PATCH iptables] libxt_cgroup2: add support for cgroup2 path matching
Hello,
On Wed, Nov 18, 2015 at 12:02:01AM +0100, Jan Engelhardt wrote:
> On Tuesday 2015-11-17 20:42, Tejun Heo wrote:
> >+static void cgroup2_save(const void *ip, const struct xt_entry_match *match)
> >+{
> >+const struct xt_cgroup2_info *info = (void *)match->data;
> >+
> >+printf("%s --path %s", info->invert ? " !" : "", info->path);
> >+}
>
> Can cgroup path names contain anything fancy, like spaces, backslashes, etc.?
> If so, xtables_save_string() will be needed here.
Will update.
> >+static struct xtables_match cgroup2_match = {
> >+.family = NFPROTO_UNSPEC,
> >+.name = "cgroup2",
> >+.version= XTABLES_VERSION,
> >+.size = XT_ALIGN(sizeof(struct xt_cgroup2_info)),
> >+.userspacesize = XT_ALIGN(sizeof(struct xt_cgroup2_info)),
>
> userspacesize must not include xt_cgroup2_info.priv.
> Change to offsetof(...), cf. other .c modules which do this.
Ah, okay.
...
> >+\fBIMPORTANT\fP: when being used in the INPUT chain, the cgroup2
> >+matcher is currently only of limited functionality, meaning it
> >+will only match on packets that are processed for local sockets
> >+through early socket demuxing. Therefore, general usage on the
> >+INPUT chain is disadviced unless the implications are well
>
> is disadviced (sic) -> is not advised
Will update. That's copied verbatim from xt_cgroup tho. Will create
a patch to update that too.
Thanks.
--
tejun
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Re: [PATCH iptables] libxt_cgroup2: add support for cgroup2 path matching
On Tuesday 2015-11-17 20:42, Tejun Heo wrote:
>+static void cgroup2_save(const void *ip, const struct xt_entry_match *match)
>+{
>+ const struct xt_cgroup2_info *info = (void *)match->data;
>+
>+ printf("%s --path %s", info->invert ? " !" : "", info->path);
>+}
Can cgroup path names contain anything fancy, like spaces, backslashes, etc.?
If so, xtables_save_string() will be needed here.
>+static struct xtables_match cgroup2_match = {
>+ .family = NFPROTO_UNSPEC,
>+ .name = "cgroup2",
>+ .version= XTABLES_VERSION,
>+ .size = XT_ALIGN(sizeof(struct xt_cgroup2_info)),
>+ .userspacesize = XT_ALIGN(sizeof(struct xt_cgroup2_info)),
userspacesize must not include xt_cgroup2_info.priv.
Change to offsetof(...), cf. other .c modules which do this.
>+++ b/extensions/libxt_cgroup2.man
>@@ -0,0 +1,24 @@
>+.TP
>+[\fB!\fP] \fB\-\-path\fP \fIpath\fP
>+Match cgroup2 membership.
>+
>+Each socket is associated with the v2 cgroup of the creating process.
>+This matches packets coming from or going to all sockets in the
>+sub-hierarchy of the specified path. The path should be relative to
>+the root of the cgroup2 hierarchy. Can be used in the OUTPUT and
>+INPUT chains to assign particular firewall policies for aggregated
>+processes on the system. This allows for more fine-grained firewall
>+policies that only match for a subset of the system's processes.
>+
>+\fBIMPORTANT\fP: when being used in the INPUT chain, the cgroup2
>+matcher is currently only of limited functionality, meaning it
>+will only match on packets that are processed for local sockets
>+through early socket demuxing. Therefore, general usage on the
>+INPUT chain is disadviced unless the implications are well
is disadviced (sic) -> is not advised
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[PATCH iptables] libxt_cgroup2: add support for cgroup2 path matching
This patch adds the extension for the xt_cgroup2 which matches packets
based on the v2 cgroup path of the associated socket.
Signed-off-by: Tejun Heo
Cc: Daniel Borkmann
---
extensions/libxt_cgroup2.c | 70 +++
extensions/libxt_cgroup2.man | 24
include/linux/netfilter/xt_cgroup2.h | 14 +++
3 files changed, 108 insertions(+)
--- /dev/null
+++ b/extensions/libxt_cgroup2.c
@@ -0,0 +1,70 @@
+#include
+#include
+#include
+#include
+#include
+
+enum {
+ O_CGROUP2_PATH,
+};
+
+static void cgroup2_help(void)
+{
+ printf(
+"cgroup2 match options:\n"
+"[!] --path path path relative to cgroup2 root, recursive
match\n");
+}
+
+static const struct xt_option_entry cgroup2_opts[] = {
+ {
+ .name = "path",
+ .id = O_CGROUP2_PATH,
+ .type = XTTYPE_STRING,
+ .flags = XTOPT_INVERT | XTOPT_MAND | XTOPT_PUT,
+ XTOPT_POINTER(struct xt_cgroup2_info, path)
+ },
+ XTOPT_TABLEEND,
+};
+
+static void cgroup2_parse(struct xt_option_call *cb)
+{
+ struct xt_cgroup2_info *info = cb->data;
+
+ xtables_option_parse(cb);
+
+ if (cb->invert)
+ info->invert = true;
+}
+
+static void cgroup2_print(const void *ip, const struct xt_entry_match *match,
+ int numeric)
+{
+ const struct xt_cgroup2_info *info = (void *)match->data;
+
+ printf(" cgroup2 %s%s", info->invert ? "! ":"", info->path);
+}
+
+static void cgroup2_save(const void *ip, const struct xt_entry_match *match)
+{
+ const struct xt_cgroup2_info *info = (void *)match->data;
+
+ printf("%s --path %s", info->invert ? " !" : "", info->path);
+}
+
+static struct xtables_match cgroup2_match = {
+ .family = NFPROTO_UNSPEC,
+ .name = "cgroup2",
+ .version= XTABLES_VERSION,
+ .size = XT_ALIGN(sizeof(struct xt_cgroup2_info)),
+ .userspacesize = XT_ALIGN(sizeof(struct xt_cgroup2_info)),
+ .help = cgroup2_help,
+ .print = cgroup2_print,
+ .save = cgroup2_save,
+ .x6_parse = cgroup2_parse,
+ .x6_options = cgroup2_opts,
+};
+
+void _init(void)
+{
+ xtables_register_match(&cgroup2_match);
+}
--- /dev/null
+++ b/extensions/libxt_cgroup2.man
@@ -0,0 +1,24 @@
+.TP
+[\fB!\fP] \fB\-\-path\fP \fIpath\fP
+Match cgroup2 membership.
+
+Each socket is associated with the v2 cgroup of the creating process.
+This matches packets coming from or going to all sockets in the
+sub-hierarchy of the specified path. The path should be relative to
+the root of the cgroup2 hierarchy. Can be used in the OUTPUT and
+INPUT chains to assign particular firewall policies for aggregated
+processes on the system. This allows for more fine-grained firewall
+policies that only match for a subset of the system's processes.
+
+\fBIMPORTANT\fP: when being used in the INPUT chain, the cgroup2
+matcher is currently only of limited functionality, meaning it
+will only match on packets that are processed for local sockets
+through early socket demuxing. Therefore, general usage on the
+INPUT chain is disadviced unless the implications are well
+understood.
+.PP
+Example:
+.IP
+iptables \-A OUTPUT \-p tcp \-\-sport 80 \-m cgroup2 ! \-\-path
service/http-server \-j DROP
+.PP
+Available since Linux 4.5.
--- /dev/null
+++ b/include/linux/netfilter/xt_cgroup2.h
@@ -0,0 +1,14 @@
+#ifndef _XT_CGROUP2_H
+#define _XT_CGROUP2_H
+
+#include
+
+struct xt_cgroup2_info {
+ charpath[PATH_MAX];
+ __u8invert;
+
+ /* kernel internal data */
+ void*priv;
+};
+
+#endif /* _XT_CGROUP2_H */
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