This patch adds the new "flow_offload" expression to select what flows
are offloaded to an existing flowtable.

Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 include/libnftnl/expr.h             |   4 +
 include/linux/netfilter/nf_tables.h |  11 +++
 src/Makefile.am                     |   1 +
 src/expr/flow_offload.c             | 184 ++++++++++++++++++++++++++++++++++++
 src/expr_ops.c                      |   2 +
 5 files changed, 202 insertions(+)
 create mode 100644 src/expr/flow_offload.c

diff --git a/include/libnftnl/expr.h b/include/libnftnl/expr.h
index f37f50963d6c..76df94276c46 100644
--- a/include/libnftnl/expr.h
+++ b/include/libnftnl/expr.h
@@ -221,6 +221,10 @@ enum {
 };
 
 enum {
+       NFTNL_EXPR_FLOW_TABLE_NAME = NFTNL_EXPR_BASE,
+};
+
+enum {
        NFTNL_EXPR_FWD_SREG_DEV = NFTNL_EXPR_BASE,
 };
 
diff --git a/include/linux/netfilter/nf_tables.h 
b/include/linux/netfilter/nf_tables.h
index c525e67a665d..2edccfee9506 100644
--- a/include/linux/netfilter/nf_tables.h
+++ b/include/linux/netfilter/nf_tables.h
@@ -952,6 +952,17 @@ enum nft_ct_attributes {
 };
 #define NFTA_CT_MAX            (__NFTA_CT_MAX - 1)
 
+/**
+ * enum nft_flow_attributes - ct offload expression attributes
+ * @NFTA_FLOW_TABLE_NAME: flow table name (NLA_STRING)
+ */
+enum nft_offload_attributes {
+       NFTA_FLOW_UNSPEC,
+       NFTA_FLOW_TABLE_NAME,
+       __NFTA_FLOW_MAX,
+};
+#define NFTA_FLOW_MAX          (__NFTA_FLOW_MAX - 1)
+
 enum nft_limit_type {
        NFT_LIMIT_PKTS,
        NFT_LIMIT_PKT_BYTES
diff --git a/src/Makefile.am b/src/Makefile.am
index 7708c279c9da..578b7d36d8a9 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -32,6 +32,7 @@ libnftnl_la_SOURCES = utils.c         \
                      expr/data_reg.c   \
                      expr/dup.c        \
                      expr/exthdr.c     \
+                     expr/flow_offload.c \
                      expr/fib.c        \
                      expr/fwd.c        \
                      expr/limit.c      \
diff --git a/src/expr/flow_offload.c b/src/expr/flow_offload.c
new file mode 100644
index 000000000000..a2001c9ae9db
--- /dev/null
+++ b/src/expr/flow_offload.c
@@ -0,0 +1,184 @@
+#include "internal.h"
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h> /* for memcpy */
+#include <arpa/inet.h>
+#include <errno.h>
+#include <libmnl/libmnl.h>
+#include <linux/netfilter/nf_tables.h>
+#include <libnftnl/rule.h>
+#include <libnftnl/expr.h>
+
+struct nftnl_expr_flow {
+       char                    *table_name;
+};
+
+static int nftnl_expr_flow_set(struct nftnl_expr *e, uint16_t type,
+                              const void *data, uint32_t data_len)
+{
+       struct nftnl_expr_flow *flow = nftnl_expr_data(e);
+
+       switch (type) {
+       case NFTNL_EXPR_FLOW_TABLE_NAME:
+               flow->table_name = strdup((const char *)data);
+               if (!flow->table_name)
+                       return -1;
+               break;
+       default:
+               return -1;
+       }
+       return 0;
+}
+
+static const void *nftnl_expr_flow_get(const struct nftnl_expr *e,
+                                      uint16_t type, uint32_t *data_len)
+{
+       struct nftnl_expr_flow *flow = nftnl_expr_data(e);
+
+       switch(type) {
+       case NFTNL_EXPR_FLOW_TABLE_NAME:
+               *data_len = strlen(flow->table_name) + 1;
+               return flow->table_name;
+       }
+       return NULL;
+}
+
+static int nftnl_expr_flow_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_FLOW_MAX) < 0)
+               return MNL_CB_OK;
+
+       switch(type) {
+       case NFTA_FLOW_TABLE_NAME:
+               if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0)
+                       abi_breakage();
+               break;
+       }
+
+       tb[type] = attr;
+       return MNL_CB_OK;
+}
+
+static void nftnl_expr_flow_build(struct nlmsghdr *nlh,
+                                 const struct nftnl_expr *e)
+{
+       struct nftnl_expr_flow *flow = nftnl_expr_data(e);
+
+       if (e->flags & (1 << NFTNL_EXPR_FLOW_TABLE_NAME))
+               mnl_attr_put_strz(nlh, NFTA_FLOW_TABLE_NAME, flow->table_name);
+}
+
+static int nftnl_expr_flow_parse(struct nftnl_expr *e, struct nlattr *attr)
+{
+       struct nftnl_expr_flow *flow = nftnl_expr_data(e);
+       struct nlattr *tb[NFTA_FLOW_MAX+1] = {};
+       int ret = 0;
+
+       if (mnl_attr_parse_nested(attr, nftnl_expr_flow_cb, tb) < 0)
+               return -1;
+
+       if (tb[NFTA_FLOW_TABLE_NAME]) {
+               flow->table_name =
+                       strdup(mnl_attr_get_str(tb[NFTA_FLOW_TABLE_NAME]));
+               if (!flow->table_name)
+                       return -1;
+               e->flags |= (1 << NFTNL_EXPR_FLOW_TABLE_NAME);
+       }
+
+       return ret;
+}
+
+static int
+nftnl_expr_flow_json_parse(struct nftnl_expr *e, json_t *root,
+                               struct nftnl_parse_err *err)
+{
+#ifdef JSON_PARSING
+       const char *table_name;
+
+       table_name = nftnl_jansson_parse_str(root, "flowtable", err);
+       if (table_name != NULL)
+               nftnl_expr_set_str(e, NFTNL_EXPR_FLOW_TABLE_NAME, table_name);
+
+       return 0;
+#else
+       errno = EOPNOTSUPP;
+       return -1;
+#endif
+}
+
+static int nftnl_expr_flow_export(char *buf, size_t size,
+                                 const struct nftnl_expr *e, int type)
+{
+       struct nftnl_expr_flow *l = nftnl_expr_data(e);
+       NFTNL_BUF_INIT(b, buf, size);
+
+       if (e->flags & (1 << NFTNL_EXPR_FLOW_TABLE_NAME))
+               nftnl_buf_str(&b, type, l->table_name, SET);
+
+       return nftnl_buf_done(&b);
+}
+
+static int nftnl_expr_flow_snprintf_default(char *buf, size_t size,
+                                           const struct nftnl_expr *e)
+{
+       int remain = size, offset = 0, ret;
+       struct nftnl_expr_flow *l = nftnl_expr_data(e);
+
+       ret = snprintf(buf, remain, "flowtable %s ", l->table_name);
+       SNPRINTF_BUFFER_SIZE(ret, remain, offset);
+
+       return offset;
+}
+
+static int nftnl_expr_flow_snprintf(char *buf, size_t size, uint32_t type,
+                                   uint32_t flags, const struct nftnl_expr *e)
+{
+       switch(type) {
+       case NFTNL_OUTPUT_DEFAULT:
+               return nftnl_expr_flow_snprintf_default(buf, size, e);
+       case NFTNL_OUTPUT_XML:
+       case NFTNL_OUTPUT_JSON:
+               return nftnl_expr_flow_export(buf, size, e, type);
+       default:
+               break;
+       }
+       return -1;
+}
+
+static void nftnl_expr_flow_free(const struct nftnl_expr *e)
+{
+       struct nftnl_expr_flow *flow = nftnl_expr_data(e);
+
+       xfree(flow->table_name);
+}
+
+static bool nftnl_expr_flow_cmp(const struct nftnl_expr *e1,
+                               const struct nftnl_expr *e2)
+{
+       struct nftnl_expr_flow *l1 = nftnl_expr_data(e1);
+       struct nftnl_expr_flow *l2 = nftnl_expr_data(e2);
+       bool eq = true;
+
+       if (e1->flags & (1 << NFTNL_EXPR_FLOW_TABLE_NAME))
+               eq &= !strcmp(l1->table_name, l2->table_name);
+
+       return eq;
+}
+
+struct expr_ops expr_ops_flow = {
+       .name           = "flow_offload",
+       .alloc_len      = sizeof(struct nftnl_expr_flow),
+       .max_attr       = NFTA_FLOW_MAX,
+       .free           = nftnl_expr_flow_free,
+       .cmp            = nftnl_expr_flow_cmp,
+       .set            = nftnl_expr_flow_set,
+       .get            = nftnl_expr_flow_get,
+       .parse          = nftnl_expr_flow_parse,
+       .build          = nftnl_expr_flow_build,
+       .snprintf       = nftnl_expr_flow_snprintf,
+       .json_parse     = nftnl_expr_flow_json_parse,
+};
diff --git a/src/expr_ops.c b/src/expr_ops.c
index 7a0e1e3d0a26..041bd357d370 100644
--- a/src/expr_ops.c
+++ b/src/expr_ops.c
@@ -33,6 +33,7 @@ extern struct expr_ops expr_ops_target;
 extern struct expr_ops expr_ops_dynset;
 extern struct expr_ops expr_ops_hash;
 extern struct expr_ops expr_ops_fib;
+extern struct expr_ops expr_ops_flow;
 
 static struct expr_ops expr_ops_notrack = {
        .name   = "notrack",
@@ -69,6 +70,7 @@ static struct expr_ops *expr_ops[] = {
        &expr_ops_hash,
        &expr_ops_fib,
        &expr_ops_objref,
+       &expr_ops_flow,
        NULL,
 };
 
-- 
2.11.0

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