This patch provides symmetric hash support according to source
ip address and port, and destination ip address and port.
The new attribute NFTA_HASH_TYPE has been included to support
different types of hashing functions. Currently supported
NFT_HASH_JENKINS through jhash and NFT_HASH_SYM through symhash.
The main difference between both types are:
- jhash requires an expression with sreg, symhash doesn't.
- symhash supports modulus and offset, but not seed.
Examples:
nft add rule ip nat prerouting ct mark set jhash ip saddr mod 2
nft add rule ip nat prerouting ct mark set symhash mod 2
Signed-off-by: Laura Garcia Liebana <laura.garcia@xxxxxxxxxxx>
---
include/libnftnl/expr.h | 1 +
include/linux/netfilter/nf_tables.h | 13 +++++++++++
src/expr/hash.c | 46 ++++++++++++++++++++++++++++++++-----
tests/nft-expr_hash-test.c | 4 ++++
4 files changed, 58 insertions(+), 6 deletions(-)
diff --git a/include/libnftnl/expr.h b/include/libnftnl/expr.h
index 38a4b83..6a571fe 100644
--- a/include/libnftnl/expr.h
+++ b/include/libnftnl/expr.h
@@ -227,6 +227,7 @@ enum {
NFTNL_EXPR_HASH_MODULUS,
NFTNL_EXPR_HASH_SEED,
NFTNL_EXPR_HASH_OFFSET,
+ NFTNL_EXPR_HASH_TYPE,
};
enum {
diff --git a/include/linux/netfilter/nf_tables.h b/include/linux/netfilter/nf_tables.h
index b00a05d..74a42fa 100644
--- a/include/linux/netfilter/nf_tables.h
+++ b/include/linux/netfilter/nf_tables.h
@@ -793,6 +793,17 @@ enum nft_rt_keys {
};
/**
+ * enum nft_hash_types - nf_tables hash expression types
+ *
+ * @NFT_HASH_JENKINS: Jenkins Hash
+ * @NFT_HASH_SYM: Symmetric Hash
+ */
+enum nft_hash_types {
+ NFT_HASH_JENKINS,
+ NFT_HASH_SYM,
+};
+
+/**
* enum nft_hash_attributes - nf_tables hash expression netlink attributes
*
* @NFTA_HASH_SREG: source register (NLA_U32)
@@ -801,6 +812,7 @@ enum nft_rt_keys {
* @NFTA_HASH_MODULUS: modulus value (NLA_U32)
* @NFTA_HASH_SEED: seed value (NLA_U32)
* @NFTA_HASH_OFFSET: add this offset value to hash result (NLA_U32)
+ * @NFTA_HASH_TYPE: hash operation (NLA_U32: nft_hash_types)
*/
enum nft_hash_attributes {
NFTA_HASH_UNSPEC,
@@ -810,6 +822,7 @@ enum nft_hash_attributes {
NFTA_HASH_MODULUS,
NFTA_HASH_SEED,
NFTA_HASH_OFFSET,
+ NFTA_HASH_TYPE,
__NFTA_HASH_MAX,
};
#define NFTA_HASH_MAX (__NFTA_HASH_MAX - 1)
diff --git a/src/expr/hash.c b/src/expr/hash.c
index 83f9317..d870510 100644
--- a/src/expr/hash.c
+++ b/src/expr/hash.c
@@ -21,6 +21,7 @@
#include <libnftnl/rule.h>
struct nftnl_expr_hash {
+ enum nft_hash_types type;
enum nft_registers sreg;
enum nft_registers dreg;
unsigned int len;
@@ -34,7 +35,6 @@ nftnl_expr_hash_set(struct nftnl_expr *e, uint16_t type,
const void *data, uint32_t data_len)
{
struct nftnl_expr_hash *hash = nftnl_expr_data(e);
-
switch (type) {
case NFTNL_EXPR_HASH_SREG:
hash->sreg = *((uint32_t *)data);
@@ -54,6 +54,9 @@ nftnl_expr_hash_set(struct nftnl_expr *e, uint16_t type,
case NFTNL_EXPR_HASH_OFFSET:
hash->offset = *((uint32_t *)data);
break;
+ case NFTNL_EXPR_HASH_TYPE:
+ hash->type = *((uint32_t *)data);
+ break;
default:
return -1;
}
@@ -85,6 +88,9 @@ nftnl_expr_hash_get(const struct nftnl_expr *e, uint16_t type,
case NFTNL_EXPR_HASH_OFFSET:
*data_len = sizeof(hash->offset);
return &hash->offset;
+ case NFTNL_EXPR_HASH_TYPE:
+ *data_len = sizeof(hash->type);
+ return &hash->type;
}
return NULL;
}
@@ -104,6 +110,7 @@ static int nftnl_expr_hash_cb(const struct nlattr *attr, void *data)
case NFTA_HASH_MODULUS:
case NFTA_HASH_SEED:
case NFTA_HASH_OFFSET:
+ case NFTA_HASH_TYPE:
if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
abi_breakage();
break;
@@ -130,6 +137,8 @@ nftnl_expr_hash_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
mnl_attr_put_u32(nlh, NFTA_HASH_SEED, htonl(hash->seed));
if (e->flags & (1 << NFTNL_EXPR_HASH_OFFSET))
mnl_attr_put_u32(nlh, NFTA_HASH_OFFSET, htonl(hash->offset));
+ if (e->flags & (1 << NFTNL_EXPR_HASH_TYPE))
+ mnl_attr_put_u32(nlh, NFTA_HASH_TYPE, htonl(hash->type));
}
static int
@@ -166,6 +175,10 @@ nftnl_expr_hash_parse(struct nftnl_expr *e, struct nlattr *attr)
hash->offset = ntohl(mnl_attr_get_u32(tb[NFTA_HASH_OFFSET]));
e->flags |= (1 << NFTNL_EXPR_HASH_OFFSET);
}
+ if (tb[NFTA_HASH_TYPE]) {
+ hash->type = ntohl(mnl_attr_get_u32(tb[NFTA_HASH_TYPE]));
+ e->flags |= (1 << NFTNL_EXPR_HASH_TYPE);
+ }
return ret;
}
@@ -174,7 +187,7 @@ static int nftnl_expr_hash_json_parse(struct nftnl_expr *e, json_t *root,
struct nftnl_parse_err *err)
{
#ifdef JSON_PARSING
- uint32_t sreg, dreg, len, modulus, seed, offset;
+ uint32_t sreg, dreg, len, modulus, seed, offset, type;
if (nftnl_jansson_parse_reg(root, "sreg", NFTNL_TYPE_U32,
&sreg, err) == 0)
@@ -200,6 +213,10 @@ static int nftnl_expr_hash_json_parse(struct nftnl_expr *e, json_t *root,
&offset, err) == 0)
nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_OFFSET, offset);
+ if (nftnl_jansson_parse_val(root, "type", NFTNL_TYPE_U32,
+ &type, err) == 0)
+ nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_TYPE, type);
+
return 0;
#else
errno = EOPNOTSUPP;
@@ -214,10 +231,23 @@ nftnl_expr_hash_snprintf_default(char *buf, size_t size,
struct nftnl_expr_hash *hash = nftnl_expr_data(e);
int len = size, offset = 0, ret;
- ret = snprintf(buf, len, "reg %u = jhash(reg %u, %u, 0x%x) %% mod %u ",
- hash->dreg, hash->sreg, hash->len, hash->seed,
- hash->modulus);
- SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+ switch (hash->type) {
+ case NFT_HASH_SYM:
+ ret =
+ snprintf(buf, len, "reg %u = symhash() %% mod %u ", hash->dreg,
+ hash->modulus);
+ SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+ break;
+ case NFT_HASH_JENKINS:
+ default:
+ ret =
+ snprintf(buf, len,
+ "reg %u = jhash(reg %u, %u, 0x%x) %% mod %u ",
+ hash->dreg, hash->sreg, hash->len, hash->seed,
+ hash->modulus);
+ SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+ break;
+ }
if (hash->offset) {
ret = snprintf(buf + offset, len, "offset %u ", hash->offset);
@@ -246,6 +276,8 @@ static int nftnl_expr_hash_export(char *buf, size_t size,
nftnl_buf_u32(&b, type, hash->seed, SEED);
if (e->flags & (1 << NFTNL_EXPR_HASH_OFFSET))
nftnl_buf_u32(&b, type, hash->offset, OFFSET);
+ if (e->flags & (1 << NFTNL_EXPR_HASH_TYPE))
+ nftnl_buf_u32(&b, type, hash->type, TYPE);
return nftnl_buf_done(&b);
}
@@ -285,6 +317,8 @@ static bool nftnl_expr_hash_cmp(const struct nftnl_expr *e1,
eq &= (h1->seed == h2->seed);
if (e1->flags & (1 << NFTNL_EXPR_HASH_OFFSET))
eq &= (h1->offset == h2->offset);
+ if (e1->flags & (1 << NFTNL_EXPR_HASH_TYPE))
+ eq &= (h1->type == h2->type);
return eq;
}
diff --git a/tests/nft-expr_hash-test.c b/tests/nft-expr_hash-test.c
index d928234..7be6e9e 100644
--- a/tests/nft-expr_hash-test.c
+++ b/tests/nft-expr_hash-test.c
@@ -45,6 +45,9 @@ static void cmp_nftnl_expr(struct nftnl_expr *rule_a,
if (nftnl_expr_get_u32(rule_a, NFTNL_EXPR_HASH_OFFSET) !=
nftnl_expr_get_u32(rule_b, NFTNL_EXPR_HASH_OFFSET))
print_err("Expr NFTNL_EXPR_HASH_OFFSET mismatches");
+ if (nftnl_expr_get_u32(rule_a, NFTNL_EXPR_HASH_TYPE) !=
+ nftnl_expr_get_u32(rule_b, NFTNL_EXPR_HASH_TYPE))
+ print_err("Expr NFTNL_EXPR_HASH_TYPE mismatches");
}
int main(int argc, char *argv[])
@@ -69,6 +72,7 @@ int main(int argc, char *argv[])
nftnl_expr_set_u32(ex, NFTNL_EXPR_HASH_MODULUS, 0x78123456);
nftnl_expr_set_u32(ex, NFTNL_EXPR_HASH_SEED, 0x78123456);
nftnl_expr_set_u32(ex, NFTNL_EXPR_HASH_OFFSET, 0x3612845);
+ nftnl_expr_set_u32(ex, NFTNL_EXPR_HASH_TYPE, NFT_HASH_JENKINS);
nftnl_rule_add_expr(a, ex);
--
2.11.0
--
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