Signed-off-by: Fernando Fernandez Mancera <ffmanc...@riseup.net>
---
include/libnftnl/expr.h | 6 +
include/linux/netfilter/nf_tables.h | 17 +++
src/Makefile.am | 1 +
src/expr/synproxy.c | 170 ++++++++++++++++++++++++++++
src/expr_ops.c | 2 +
5 files changed, 196 insertions(+)
create mode 100644 src/expr/synproxy.c
diff --git a/include/libnftnl/expr.h b/include/libnftnl/expr.h
index b2f8d75..3e0f5b0 100644
--- a/include/libnftnl/expr.h
+++ b/include/libnftnl/expr.h
@@ -291,6 +291,12 @@ enum {
NFTNL_EXPR_XFRM_SPNUM,
};
+enum {
+ NFTNL_EXPR_SYNPROXY_MSS = NFTNL_EXPR_BASE,
+ NFTNL_EXPR_SYNPROXY_WSCALE,
+ NFTNL_EXPR_SYNPROXY_FLAGS,
+};
+
#ifdef __cplusplus
} /* extern "C" */
#endif
diff --git a/include/linux/netfilter/nf_tables.h
b/include/linux/netfilter/nf_tables.h
index fd38cdc..b7867ed 100644
--- a/include/linux/netfilter/nf_tables.h
+++ b/include/linux/netfilter/nf_tables.h
@@ -951,6 +951,23 @@ enum nft_osf_attributes {
};
#define NFTA_OSF_MAX (__NFTA_OSF_MAX - 1)
+/**
+ * enum nft_synproxy_attributes - nf_tables synproxy expression
+ * netlink attributes
+ *
+ * @NFTA_SYNPROXY_MSS: mss value sent to the backend (NLA_U16)
+ * @NFTA_SYNPROXY_WSCALE: wscale value sent to the backend (NLA_U8)
+ * @NFTA_SYNPROXY_FLAGS: flags (NLA_U32)
+ */
+enum nft_synproxy_attributes {
+ NFTA_SYNPROXY_UNSPEC,
+ NFTA_SYNPROXY_MSS,
+ NFTA_SYNPROXY_WSCALE,
+ NFTA_SYNPROXY_FLAGS,
+ __NFTA_SYNPROXY_MAX,
+};
+#define NFTA_SYNPROXY_MAX (__NFTA_SYNPROXY_MAX - 1)
+
/**
* enum nft_ct_keys - nf_tables ct expression keys
*
diff --git a/src/Makefile.am b/src/Makefile.am
index 2d5873f..d100a9e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -58,6 +58,7 @@ libnftnl_la_SOURCES = utils.c \
expr/socket.c \
expr/osf.c \
expr/xfrm.c \
+ expr/synproxy.c \
obj/counter.c \
obj/ct_helper.c \
obj/quota.c \
diff --git a/src/expr/synproxy.c b/src/expr/synproxy.c
new file mode 100644
index 0000000..245f4fb
--- /dev/null
+++ b/src/expr/synproxy.c
@@ -0,0 +1,170 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <errno.h>
+#include <linux/netfilter/nf_tables.h>
+
+#include "internal.h"
+#include <libmnl/libmnl.h>
+#include <libnftnl/expr.h>
+#include <libnftnl/rule.h>
+
+struct nftnl_expr_synproxy {
+ uint16_t mss;
+ uint8_t wscale;
+ uint32_t flags;
+};
+
+static int nftnl_expr_synproxy_set(struct nftnl_expr *e, uint16_t type,
+ const void *data, uint32_t data_len)
+{
+ struct nftnl_expr_synproxy *synproxy = nftnl_expr_data(e);
+
+ switch(type) {
+ case NFTNL_EXPR_SYNPROXY_MSS:
+ memcpy(&synproxy->mss, data, sizeof(synproxy->mss));
+ break;
+ case NFTNL_EXPR_SYNPROXY_WSCALE:
+ memcpy(&synproxy->wscale, data, sizeof(synproxy->wscale));
+ break;
+ case NFTNL_EXPR_SYNPROXY_FLAGS:
+ memcpy(&synproxy->flags, data, sizeof(synproxy->flags));
+ break;
+ }
+ return 0;
+}
+
+static const void *
+nftnl_expr_synproxy_get(const struct nftnl_expr *e, uint16_t type,
+ uint32_t *data_len)
+{
+ struct nftnl_expr_synproxy *synproxy = nftnl_expr_data(e);
+
+ switch(type) {
+ case NFTNL_EXPR_SYNPROXY_MSS:
+ *data_len = sizeof(synproxy->mss);
+ return &synproxy->mss;
+ case NFTNL_EXPR_SYNPROXY_WSCALE:
+ *data_len = sizeof(synproxy->wscale);
+ return &synproxy->wscale;
+ case NFTNL_EXPR_SYNPROXY_FLAGS:
+ *data_len = sizeof(synproxy->flags);
+ return &synproxy->flags;
+ }
+ return NULL;
+}
+
+static int nftnl_expr_synproxy_cb(const struct nlattr *attr, void *data)
+{
+ const struct nlattr **tb = data;
+ int type = mnl_attr_get_type(attr);
+
+ if (mnl_attr_type_valid(attr, NFTA_SYNPROXY_MAX) < 0)
+ return MNL_CB_OK;
+
+ switch(type) {
+ case NFTNL_EXPR_SYNPROXY_MSS:
+ if (mnl_attr_validate(attr, MNL_TYPE_U16) < 0)
+ abi_breakage();
+ break;
+
+ case NFTNL_EXPR_SYNPROXY_WSCALE:
+ if (mnl_attr_validate(attr, MNL_TYPE_U8) < 0)
+ abi_breakage();
+ break;
+
+ case NFTNL_EXPR_SYNPROXY_FLAGS:
+ if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
+ abi_breakage();
+ break;
+ }
+
+ tb[type] = attr;
+ return MNL_CB_OK;
+}
+
+static void
+nftnl_expr_synproxy_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
+{
+ struct nftnl_expr_synproxy *synproxy = nftnl_expr_data(e);
+
+ if (e->flags & (1 << NFTNL_EXPR_SYNPROXY_MSS))
+ mnl_attr_put_u16(nlh, NFTNL_EXPR_SYNPROXY_MSS,
+ htons(synproxy->mss));
+ if (e->flags & (1 << NFTNL_EXPR_SYNPROXY_WSCALE))
+ mnl_attr_put_u8(nlh, NFTNL_EXPR_SYNPROXY_WSCALE,
+ synproxy->wscale);
+ if (e->flags & (1 << NFTNL_EXPR_SYNPROXY_FLAGS))
+ mnl_attr_put_u32(nlh, NFTNL_EXPR_SYNPROXY_FLAGS,
+ htonl(synproxy->flags));
+}
+
+static int
+nftnl_expr_synproxy_parse(struct nftnl_expr *e, struct nlattr *attr)
+{
+ struct nftnl_expr_synproxy *synproxy = nftnl_expr_data(e);
+ struct nlattr *tb[NFTA_SYNPROXY_MAX + 1] = {};
+
+ if (mnl_attr_parse_nested(attr, nftnl_expr_synproxy_cb, tb) < 0)
+ return -1;
+
+ if (tb[NFTA_SYNPROXY_MSS]) {
+ synproxy->mss = ntohs(mnl_attr_get_u16(tb[NFTA_SYNPROXY_MSS]));
+ e->flags |= (1 << NFTNL_EXPR_SYNPROXY_MSS);
+ }
+
+ if (tb[NFTA_SYNPROXY_WSCALE]) {
+ synproxy->wscale = mnl_attr_get_u8(tb[NFTA_SYNPROXY_WSCALE]);
+ e->flags |= (1 << NFTNL_EXPR_SYNPROXY_WSCALE);
+ }
+
+ if (tb[NFTA_SYNPROXY_FLAGS]) {
+ synproxy->flags =
ntohl(mnl_attr_get_u32(tb[NFTA_SYNPROXY_FLAGS]));
+ e->flags |= (1 << NFTNL_EXPR_SYNPROXY_FLAGS);
+ }
+
+ return 0;
+}
+
+static int nftnl_expr_synproxy_snprintf_default(char *buf, size_t size,
+ const struct nftnl_expr *e)
+{
+ struct nftnl_expr_synproxy *synproxy = nftnl_expr_data(e);
+ int ret, offset = 0, len = size;
+
+ if (e->flags & (1 << NFTNL_EXPR_SYNPROXY_MSS) &&
+ e->flags & (1 << NFTNL_EXPR_SYNPROXY_WSCALE)) {
+ ret = snprintf(buf, len, "mss %u wscale %u ", synproxy->mss,
+ synproxy->wscale);
+ SNPRINTF_BUFFER_SIZE(ret, len, offset);
+ }
+
+ return offset;
+}
+
+static int
+nftnl_expr_synproxy_snprintf(char *buf, size_t len, uint32_t type,
+ uint32_t flags, const struct nftnl_expr *e)
+{
+ switch(type) {
+ case NFTNL_OUTPUT_DEFAULT:
+ return nftnl_expr_synproxy_snprintf_default(buf, len, e);
+ case NFTNL_OUTPUT_XML:
+ case NFTNL_OUTPUT_JSON:
+ default:
+ break;
+ }
+ return -1;
+}
+
+struct expr_ops expr_ops_synproxy = {
+ .name = "synproxy",
+ .alloc_len = sizeof(struct nftnl_expr_synproxy),
+ .max_attr = NFTA_SYNPROXY_MAX,
+ .set = nftnl_expr_synproxy_set,
+ .get = nftnl_expr_synproxy_get,
+ .parse = nftnl_expr_synproxy_parse,
+ .build = nftnl_expr_synproxy_build,
+ .snprintf = nftnl_expr_synproxy_snprintf,
+};
diff --git a/src/expr_ops.c b/src/expr_ops.c
index 051140f..9655e2f 100644
--- a/src/expr_ops.c
+++ b/src/expr_ops.c
@@ -40,6 +40,7 @@ extern struct expr_ops expr_ops_socket;
extern struct expr_ops expr_ops_tunnel;
extern struct expr_ops expr_ops_osf;
extern struct expr_ops expr_ops_xfrm;
+extern struct expr_ops expr_ops_synproxy;
static struct expr_ops expr_ops_notrack = {
.name = "notrack",
@@ -83,6 +84,7 @@ static struct expr_ops *expr_ops[] = {
&expr_ops_tunnel,
&expr_ops_osf,
&expr_ops_xfrm,
+ &expr_ops_synproxy,
NULL,
};
--
2.20.1
