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src: make hash seed attribute optional

PATCH Applied Laura Garcia Liebana 2 participants 2 messages Nov 4, 2016 – Nov 8, 2016 netfilter

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Laura Garcia Liebana

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#0 lore raw

PATCH v3 1/4 src: make hash seed attribute optional

The hash expression requires a seed attribute to call the jhash operation, eg.

 # nft add rule x y meta mark set jhash ip saddr . ip daddr mod 2 \
	seed 0xdeadbeef

With this patch the seed attribute is optional and it's generated by a random function from userspace, eg.

 # nft add rule x y meta mark set jhash ip saddr . ip daddr mod 2

The kernel will take care of generate a random seed.

Signed-off-by Laura Garcia Liebana <[email protected]>

---
Changes in v3:
- The random generation is done in kernel side.
- Tests included.

 src/parser_bison.y         | 5 +++++
 tests/py/ip/hash.t         | 1 +
 tests/py/ip/hash.t.payload | 7 +++++++
 3 files changed, 13 insertions(+)
src/parser_bison.y +5 -0
index 17f23c5..82fec99 100644
@@ -2585,6 +2585,11 @@ hash_expr		:	JHASH	expr	MOD	NUM	SEED	NUM
 				$$ = hash_expr_alloc(&@$, $4, $6);
 				$$->hash.expr = $2;
 			}
+			|	JHASH	expr	MOD	NUM
+			{
+				$$ = hash_expr_alloc(&@$, $4, 0);
+				$$->hash.expr = $2;
+			}
 			;
 
 rt_expr			:	RT	rt_key
tests/py/ip/hash.t +1 -0
index 6dfa965..306ebfd 100644
@@ -2,4 +2,5 @@
 *ip;test-ip4;pre
 
 ct mark set jhash ip saddr . ip daddr mod 2 seed 0xdeadbeef;ok
+ct mark set jhash ip saddr . ip daddr mod 2;ok
 dnat to jhash ip saddr mod 2 seed 0xdeadbeef map { 0 : 192.168.20.100, 1 : 192.168.30.100 };ok
tests/py/ip/hash.t.payload +7 -0
index d9a22eb..1188a1b 100644
@@ -5,6 +5,13 @@ ip test-ip4 pre
   [ hash reg 1 = jhash(reg 2, 8, 0xdeadbeef) % mod 2 ]
   [ ct set mark with reg 1 ]
 
+# ct mark set jhash ip saddr . ip daddr mod 2
+ip test-ip4 pre
+  [ payload load 4b @ network header + 12 => reg 2 ]
+  [ payload load 4b @ network header + 16 => reg 13 ]
+  [ hash reg 1 = jhash(reg 2, 8, 0x0) % mod 2 ]
+  [ ct set mark with reg 1 ]
+
 # dnat to jhash ip saddr mod 2 seed 0xdeadbeef map { 0 : 192.168.20.100, 1 : 192.168.30.100 }
 __map%d test-ip4 b
 __map%d test-ip4 0
Signature · 1 line
2.9.3
maintainer Applied
#1 lore raw
Quoted 6 lines · Laura Garcia Liebana

The hash expression requires a seed attribute to call the jhash operation, eg.

 # nft add rule x y meta mark set jhash ip saddr . ip daddr mod 2 \
	seed 0xdeadbeef
Quoted 6 lines

With this patch the seed attribute is optional and it's generated by a random function from userspace, eg.

 # nft add rule x y meta mark set jhash ip saddr . ip daddr mod 2

The kernel will take care of generate a random seed.

Applied, thanks Laura.