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Message-Id: <20180601153216.10901-3-fw@strlen.de>
Date: Fri, 1 Jun 2018 17:32:13 +0200
From: Florian Westphal <fw@...len.de>
To: <netfilter-devel@...r.kernel.org>
Cc: ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
Florian Westphal <fw@...len.de>
Subject: [RFC nf-next 2/5] netfilter: nf_tables: add ebpf expression
This expression serves two purposes:
1. a middleman to invoke BPF_PROG_RUN() from nf_tables main eval loop
2. to expose the bpf program id via netlink, so userspace
can map nftables rules to their corresponding ebpf program.
2) is added in a followup patch.
Its currently not possible to attach arbitrary ebpf programs from
userspace, but this limitation is easy to remove if needed.
Signed-off-by: Florian Westphal <fw@...len.de>
---
include/net/netfilter/nf_tables_core.h | 9 ++++++
include/uapi/linux/netfilter/nf_tables.h | 18 ++++++++++++
net/netfilter/Makefile | 3 +-
net/netfilter/nf_tables_core.c | 33 ++++++++++++++++++++++
net/netfilter/nf_tables_jit.c | 48 ++++++++++++++++++++++++++++++++
5 files changed, 110 insertions(+), 1 deletion(-)
create mode 100644 net/netfilter/nf_tables_jit.c
diff --git a/include/net/netfilter/nf_tables_core.h b/include/net/netfilter/nf_tables_core.h
index e0c0c2558ec4..90087a84f127 100644
--- a/include/net/netfilter/nf_tables_core.h
+++ b/include/net/netfilter/nf_tables_core.h
@@ -15,6 +15,7 @@ extern struct nft_expr_type nft_range_type;
extern struct nft_expr_type nft_meta_type;
extern struct nft_expr_type nft_rt_type;
extern struct nft_expr_type nft_exthdr_type;
+extern struct nft_expr_type nft_ebpf_type;
int nf_tables_core_module_init(void);
void nf_tables_core_module_exit(void);
@@ -62,6 +63,14 @@ struct nft_payload_set {
extern const struct nft_expr_ops nft_payload_fast_ops;
+struct nft_ebpf {
+ struct bpf_prog *prog;
+ u8 expressions;
+ const struct nft_rule *original;
+};
+
+extern const struct nft_expr_ops nft_ebpf_fast_ops;
+
extern struct static_key_false nft_counters_enabled;
extern struct static_key_false nft_trace_enabled;
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 9c71f024f9cc..e05799652a4c 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -718,6 +718,24 @@ enum nft_payload_attributes {
};
#define NFTA_PAYLOAD_MAX (__NFTA_PAYLOAD_MAX - 1)
+/**
+ * enum nft_ebpf_attributes - nf_tables ebpf expression netlink attributes
+ *
+ * @NFTA_EBPF_FD: file descriptor holding ebpf program (NLA_S32)
+ * @NFTA_EBPF_ID: bpf program id (NLA_U32)
+ * @NFTA_EBPF_TAG: bpf tag (NLA_BINARY)
+ * @NFTA_EBPF_TAG: expressions covered by this jit (NLA_U32)
+ */
+enum nft_ebpf_attributes {
+ NFTA_EBPF_UNSPEC,
+ NFTA_EBPF_FD,
+ NFTA_EBPF_ID,
+ NFTA_EBPF_TAG,
+ NFTA_EBPF_EXPR_COUNT,
+ __NFTA_EBPF_MAX,
+};
+#define NFTA_EBPF_MAX (__NFTA_EBPF_MAX - 1)
+
enum nft_exthdr_flags {
NFT_EXTHDR_F_PRESENT = (1 << 0),
};
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 9b3434360d49..49c6e0a535f9 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -76,7 +76,8 @@ obj-$(CONFIG_NF_DUP_NETDEV) += nf_dup_netdev.o
nf_tables-objs := nf_tables_core.o nf_tables_api.o nft_chain_filter.o \
nf_tables_trace.o nft_immediate.o nft_cmp.o nft_range.o \
nft_bitwise.o nft_byteorder.o nft_payload.o nft_lookup.o \
- nft_dynset.o nft_meta.o nft_rt.o nft_exthdr.o
+ nft_dynset.o nft_meta.o nft_rt.o nft_exthdr.o \
+ nf_tables_jit.o
obj-$(CONFIG_NF_TABLES) += nf_tables.o
obj-$(CONFIG_NFT_COMPAT) += nft_compat.o
diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index 47cf667b15ca..038a15243508 100644
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -11,6 +11,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
+#include <linux/filter.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/skbuff.h>
@@ -92,6 +93,35 @@ static bool nft_payload_fast_eval(const struct nft_expr *expr,
return true;
}
+static void nft_ebpf_fast_eval(const struct nft_expr *expr,
+ struct nft_regs *regs,
+ const struct nft_pktinfo *pkt)
+{
+ const struct nft_ebpf *priv = nft_expr_priv(expr);
+ struct bpf_skb_data_end cb_saved;
+ int ret;
+
+ memcpy(&cb_saved, pkt->skb->cb, sizeof(cb_saved));
+ bpf_compute_data_pointers(pkt->skb);
+
+ ret = BPF_PROG_RUN(priv->prog, pkt->skb);
+
+ memcpy(pkt->skb->cb, &cb_saved, sizeof(cb_saved));
+
+ switch (ret) {
+ case NF_DROP:
+ case NF_ACCEPT:
+ case NFT_BREAK:
+ regs->verdict.code = ret;
+ return;
+ case NFT_CONTINUE:
+ return;
+ default:
+ pr_debug("Unknown verdict %d\n", ret);
+ regs->verdict.code = NF_DROP;
+ break;
+ }
+}
DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
static noinline void nft_update_chain_stats(const struct nft_chain *chain,
@@ -151,6 +181,8 @@ nft_do_chain(struct nft_pktinfo *pkt, void *priv)
nft_rule_for_each_expr(expr, last, rule) {
if (expr->ops == &nft_cmp_fast_ops)
nft_cmp_fast_eval(expr, ®s);
+ else if (expr->ops == &nft_ebpf_fast_ops)
+ nft_ebpf_fast_eval(expr, ®s, pkt);
else if (expr->ops != &nft_payload_fast_ops ||
!nft_payload_fast_eval(expr, ®s, pkt))
expr->ops->eval(expr, ®s, pkt);
@@ -232,6 +264,7 @@ static struct nft_expr_type *nft_basic_types[] = {
&nft_meta_type,
&nft_rt_type,
&nft_exthdr_type,
+ &nft_ebpf_type,
};
int __init nf_tables_core_module_init(void)
diff --git a/net/netfilter/nf_tables_jit.c b/net/netfilter/nf_tables_jit.c
new file mode 100644
index 000000000000..415c2acfa471
--- /dev/null
+++ b/net/netfilter/nf_tables_jit.c
@@ -0,0 +1,48 @@
+#include <linux/bpf.h>
+#include <linux/netfilter.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables_core.h>
+
+struct nft_ebpf_expression {
+ struct nft_expr e;
+ struct nft_ebpf priv;
+};
+
+static const struct nla_policy nft_ebpf_policy[NFTA_EBPF_MAX + 1] = {
+ [NFTA_EBPF_FD] = { .type = NLA_S32 },
+ [NFTA_EBPF_ID] = { .type = NLA_U32 },
+ [NFTA_EBPF_EXPR_COUNT] = { .type = NLA_U32 },
+ [NFTA_EBPF_TAG] = { .type = NLA_BINARY,
+ .len = BPF_TAG_SIZE, },
+};
+
+static int nft_ebpf_init(const struct nft_ctx *ctx,
+ const struct nft_expr *expr,
+ const struct nlattr * const tb[])
+{
+ return -EOPNOTSUPP;
+}
+
+static void nft_ebpf_destroy(const struct nft_ctx *ctx,
+ const struct nft_expr *expr)
+{
+ struct nft_ebpf *priv = nft_expr_priv(expr);
+
+ bpf_prog_put(priv->prog);
+ kfree(priv->original);
+}
+
+const struct nft_expr_ops nft_ebpf_fast_ops = {
+ .type = &nft_ebpf_type,
+ .size = NFT_EXPR_SIZE(sizeof(struct nft_ebpf)),
+ .init = nft_ebpf_init,
+ .destroy = nft_ebpf_destroy,
+};
+
+struct nft_expr_type nft_ebpf_type __read_mostly = {
+ .name = "ebpf",
+ .ops = &nft_ebpf_fast_ops,
+ .policy = nft_ebpf_policy,
+ .maxattr = NFTA_EBPF_MAX,
+ .owner = THIS_MODULE,
+};
--
2.16.4
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