Add string expression to use to match on existing "string sets" from rules.
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
include/libnftnl/expr.h | 9 ++
include/linux/netfilter/nf_tables.h | 26 ++++
src/Makefile.am | 1 +
src/expr/str.c | 223 ++++++++++++++++++++++++++++
src/expr_ops.c | 2 +
5 files changed, 261 insertions(+)
create mode 100644 src/expr/str.c
diff --git a/include/libnftnl/expr.h b/include/libnftnl/expr.h
index 00c63ab9d19b..997e19a13662 100644
--- a/include/libnftnl/expr.h
+++ b/include/libnftnl/expr.h
@@ -78,6 +78,15 @@ enum {
NFTNL_EXPR_RT_DREG,
};
+enum {
+ NFTNL_EXPR_STR_NAME = NFTNL_EXPR_BASE,
+ NFTNL_EXPR_STR_BASE,
+ NFTNL_EXPR_STR_FROM,
+ NFTNL_EXPR_STR_TO,
+ NFTNL_EXPR_STR_DREG,
+ NFTNL_EXPR_STR_FLAGS,
+};
+
enum {
NFTNL_EXPR_SOCKET_KEY = NFTNL_EXPR_BASE,
NFTNL_EXPR_SOCKET_DREG,
diff --git a/include/linux/netfilter/nf_tables.h b/include/linux/netfilter/nf_tables.h
index d7a668199611..8ce2400952c0 100644
--- a/include/linux/netfilter/nf_tables.h
+++ b/include/linux/netfilter/nf_tables.h
@@ -1711,6 +1711,32 @@ enum nft_string_hook_attributes {
};
#define NFTA_STRING_MAX (__NFTA_STRING_MAX - 1)
+enum nft_string_flags {
+ NFT_STR_F_PRESENT = (1 << 0),
+};
+
+/**
+ * enum nft_str_hook_attributes - nf_tables string expression netlink attributes
+ *
+ * @NFTA_STR_NAME: string set name (NLA_STRING)
+ * @NFTA_STR_BASE: payload base (NLA_U32: nft_payload_bases)
+ * @NFTA_STR_FROM: offset to start matching from (NLA_U32)
+ * @NFTA_STR_TO: offset to end matching to (NLA_U32)
+ * @NFTA_STR_DREG: destination register (NLA_U32: nft_registers)
+ * @NFTA_STR_FLAGS: flags (NLA_U32)
+ */
+enum nft_str_hook_attributes {
+ NFTA_STR_UNSPEC,
+ NFTA_STR_NAME,
+ NFTA_STR_BASE,
+ NFTA_STR_FROM,
+ NFTA_STR_TO,
+ NFTA_STR_DREG,
+ NFTA_STR_FLAGS,
+ __NFTA_STR_MAX
+};
+#define NFTA_STR_MAX (__NFTA_STR_MAX - 1)
+
/**
* enum nft_osf_attributes - nftables osf expression netlink attributes
*
diff --git a/src/Makefile.am b/src/Makefile.am
index 24825d4e3e38..15ce569636c8 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -52,6 +52,7 @@ libnftnl_la_SOURCES = utils.c \
expr/quota.c \
expr/reject.c \
expr/rt.c \
+ expr/str.c \
expr/target.c \
expr/tunnel.c \
expr/masq.c \
diff --git a/src/expr/str.c b/src/expr/str.c
new file mode 100644
index 000000000000..398fdce22f10
--- /dev/null
+++ b/src/expr/str.c
@@ -0,0 +1,223 @@
+/*
+ * Copyright (c) 2022 Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#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_str {
+ const char *name;
+ uint32_t base;
+ uint32_t from;
+ uint32_t to;
+ uint32_t flags;
+ enum nft_registers dreg;
+};
+
+static int
+nftnl_expr_str_set(struct nftnl_expr *e, uint16_t type,
+ const void *data, uint32_t data_len)
+{
+ struct nftnl_expr_str *str = nftnl_expr_data(e);
+
+ switch (type) {
+ case NFTNL_EXPR_STR_NAME:
+ if (str->name)
+ xfree(str->name);
+
+ str->name = strdup(data);
+ if (!str->name)
+ return -1;
+ break;
+ case NFTNL_EXPR_STR_BASE:
+ memcpy(&str->base, data, sizeof(str->base));
+ break;
+ case NFTNL_EXPR_STR_FROM:
+ memcpy(&str->from, data, sizeof(str->from));
+ break;
+ case NFTNL_EXPR_STR_TO:
+ memcpy(&str->to, data, sizeof(str->to));
+ break;
+ case NFTNL_EXPR_STR_DREG:
+ memcpy(&str->dreg, data, sizeof(str->dreg));
+ break;
+ case NFTNL_EXPR_STR_FLAGS:
+ memcpy(&str->flags, data, sizeof(str->flags));
+ break;
+ default:
+ return -1;
+ }
+ return 0;
+}
+
+static const void *
+nftnl_expr_str_get(const struct nftnl_expr *e, uint16_t type, uint32_t *data_len)
+{
+ struct nftnl_expr_str *str = nftnl_expr_data(e);
+
+ switch (type) {
+ case NFTNL_EXPR_STR_NAME:
+ if (str->name)
+ *data_len = strlen(str->name);
+ else
+ *data_len = 0;
+
+ return str->name;
+ case NFTNL_EXPR_STR_BASE:
+ *data_len = sizeof(str->base);
+ return &str->base;
+ case NFTNL_EXPR_STR_FROM:
+ *data_len = sizeof(str->from);
+ return &str->from;
+ case NFTNL_EXPR_STR_TO:
+ *data_len = sizeof(str->to);
+ return &str->to;
+ case NFTNL_EXPR_STR_DREG:
+ *data_len = sizeof(str->dreg);
+ return &str->dreg;
+ case NFTNL_EXPR_STR_FLAGS:
+ *data_len = sizeof(str->flags);
+ return &str->flags;
+ }
+ return NULL;
+}
+
+static int nftnl_expr_str_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_STR_MAX) < 0)
+ return MNL_CB_OK;
+
+ switch (type) {
+ case NFTA_STR_BASE:
+ case NFTA_STR_FROM:
+ case NFTA_STR_TO:
+ case NFTA_STR_DREG:
+ case NFTA_STR_FLAGS:
+ if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
+ abi_breakage();
+ break;
+ case NFTA_STR_NAME:
+ if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0)
+ abi_breakage();
+ break;
+ }
+
+ tb[type] = attr;
+ return MNL_CB_OK;
+}
+
+static void
+nftnl_expr_str_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
+{
+ struct nftnl_expr_str *str = nftnl_expr_data(e);
+
+ if (e->flags & (1 << NFTNL_EXPR_STR_BASE))
+ mnl_attr_put_u32(nlh, NFTA_STR_BASE, htonl(str->base));
+ if (e->flags & (1 << NFTNL_EXPR_STR_FROM))
+ mnl_attr_put_u32(nlh, NFTA_STR_FROM, htonl(str->from));
+ if (e->flags & (1 << NFTNL_EXPR_STR_TO))
+ mnl_attr_put_u32(nlh, NFTA_STR_TO, htonl(str->to));
+ if (e->flags & (1 << NFTNL_EXPR_STR_NAME))
+ mnl_attr_put_strz(nlh, NFTA_STR_NAME, str->name);
+ if (e->flags & (1 << NFTNL_EXPR_STR_DREG))
+ mnl_attr_put_u32(nlh, NFTA_STR_DREG, htonl(str->dreg));
+ if (e->flags & (1 << NFTNL_EXPR_STR_FLAGS))
+ mnl_attr_put_u32(nlh, NFTA_STR_FLAGS, htonl(str->flags));
+}
+
+static int
+nftnl_expr_str_parse(struct nftnl_expr *e, struct nlattr *attr)
+{
+ struct nftnl_expr_str *str = nftnl_expr_data(e);
+ struct nlattr *tb[NFTA_STR_MAX + 1] = {};
+
+ if (mnl_attr_parse_nested(attr, nftnl_expr_str_cb, tb) < 0)
+ return -1;
+
+ if (tb[NFTA_STR_BASE]) {
+ str->base = ntohl(mnl_attr_get_u32(tb[NFTA_STR_BASE]));
+ e->flags |= (1 << NFTNL_EXPR_STR_BASE);
+ }
+ if (tb[NFTA_STR_FROM]) {
+ str->from = ntohl(mnl_attr_get_u32(tb[NFTA_STR_FROM]));
+ e->flags |= (1 << NFTNL_EXPR_STR_FROM);
+ }
+ if (tb[NFTA_STR_FROM]) {
+ str->to = ntohl(mnl_attr_get_u32(tb[NFTA_STR_TO]));
+ e->flags |= (1 << NFTNL_EXPR_STR_TO);
+ }
+ if (tb[NFTA_STR_NAME]) {
+ str->name = strdup(mnl_attr_get_str(tb[NFTA_STR_NAME]));
+ if (!str->name)
+ return -1;
+
+ e->flags |= (1 << NFTNL_EXPR_STR_NAME);
+ }
+ if (tb[NFTA_STR_DREG]) {
+ str->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_STR_DREG]));
+ e->flags |= (1 << NFTNL_EXPR_STR_DREG);
+ }
+ if (tb[NFTA_STR_FLAGS]) {
+ str->flags = ntohl(mnl_attr_get_u32(tb[NFTA_STR_FLAGS]));
+ e->flags |= (1 << NFTNL_EXPR_STR_FLAGS);
+ }
+
+ return 0;
+}
+
+static const char *nft_str_base(uint32_t base)
+{
+ switch (base) {
+ case NFT_PAYLOAD_NETWORK_HEADER:
+ return "nh";
+ case NFT_PAYLOAD_TRANSPORT_HEADER:
+ return "th";
+ case NFT_PAYLOAD_INNER_HEADER:
+ return "ih";
+ default:
+ break;
+ }
+ return "unknown";
+}
+
+static int
+nftnl_expr_str_snprintf(char *buf, size_t len,
+ uint32_t flags, const struct nftnl_expr *e)
+{
+ struct nftnl_expr_str *str = nftnl_expr_data(e);
+
+ if (e->flags & (1 << NFTNL_EXPR_STR_DREG)) {
+ return snprintf(buf, len, "search @%s,%s %u-%u => reg %u",
+ str->name, nft_str_base(str->base),
+ str->from, str->to, str->dreg);
+ }
+ return 0;
+}
+
+struct expr_ops expr_ops_str = {
+ .name = "string",
+ .alloc_len = sizeof(struct nftnl_expr_str),
+ .max_attr = NFTA_STR_MAX,
+ .set = nftnl_expr_str_set,
+ .get = nftnl_expr_str_get,
+ .parse = nftnl_expr_str_parse,
+ .build = nftnl_expr_str_build,
+ .output = nftnl_expr_str_snprintf,
+};
diff --git a/src/expr_ops.c b/src/expr_ops.c
index 7248e4f98b0a..85ea82008e1a 100644
--- a/src/expr_ops.c
+++ b/src/expr_ops.c
@@ -30,6 +30,7 @@ extern struct expr_ops expr_ops_range;
extern struct expr_ops expr_ops_redir;
extern struct expr_ops expr_ops_reject;
extern struct expr_ops expr_ops_rt;
+extern struct expr_ops expr_ops_str;
extern struct expr_ops expr_ops_queue;
extern struct expr_ops expr_ops_quota;
extern struct expr_ops expr_ops_target;
@@ -74,6 +75,7 @@ static struct expr_ops *expr_ops[] = {
&expr_ops_redir,
&expr_ops_reject,
&expr_ops_rt,
+ &expr_ops_str,
&expr_ops_queue,
&expr_ops_quota,
&expr_ops_target,
--
2.30.2
