Commit 38d57551 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'inet-siphash' 



Eric Dumazet says:

====================
inet: use siphash in exception handling

A group of security researchers brought to our attention
the weakness of hash functions used in rt6_exception_hash()
and fnhe_hashfun()

I made two distinct patches to help backports, since IPv6
part was added in 4.15
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 92ea47fe 6457378f

net/ipv4/route.c

+6 −6
Original line number Diff line number Diff line
@@ -600,14 +600,14 @@ static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash) 
	return oldest;

}



static inline u32 fnhe_hashfun(__be32 daddr)

static u32 fnhe_hashfun(__be32 daddr)

{

	static u32 fnhe_hashrnd __read_mostly;

	u32 hval;

	static siphash_key_t fnhe_hash_key __read_mostly;

	u64 hval;



	net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));

	hval = jhash_1word((__force u32)daddr, fnhe_hashrnd);

	return hash_32(hval, FNHE_HASH_SHIFT);

	net_get_random_once(&fnhe_hash_key, sizeof(fnhe_hash_key));

	hval = siphash_1u32((__force u32)daddr, &fnhe_hash_key);

	return hash_64(hval, FNHE_HASH_SHIFT);

}



static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)

net/ipv6/route.c

+14 −6
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ 
#include <linux/nsproxy.h>

#include <linux/slab.h>

#include <linux/jhash.h>

#include <linux/siphash.h>

#include <net/net_namespace.h>

#include <net/snmp.h>

#include <net/ipv6.h>
@@ -1484,17 +1485,24 @@ static void rt6_exception_remove_oldest(struct rt6_exception_bucket *bucket) 
static u32 rt6_exception_hash(const struct in6_addr *dst,

			      const struct in6_addr *src)

{

	static u32 seed __read_mostly;

	u32 val;

	static siphash_key_t rt6_exception_key __read_mostly;

	struct {

		struct in6_addr dst;

		struct in6_addr src;

	} __aligned(SIPHASH_ALIGNMENT) combined = {

		.dst = *dst,

	};

	u64 val;



	net_get_random_once(&seed, sizeof(seed));

	val = jhash2((const u32 *)dst, sizeof(*dst)/sizeof(u32), seed);

	net_get_random_once(&rt6_exception_key, sizeof(rt6_exception_key));



#ifdef CONFIG_IPV6_SUBTREES

	if (src)

		val = jhash2((const u32 *)src, sizeof(*src)/sizeof(u32), val);

		combined.src = *src;

#endif

	return hash_32(val, FIB6_EXCEPTION_BUCKET_SIZE_SHIFT);

	val = siphash(&combined, sizeof(combined), &rt6_exception_key);



	return hash_64(val, FIB6_EXCEPTION_BUCKET_SIZE_SHIFT);

}



/* Helper function to find the cached rt in the hash table