[PATCH 4.9 259/264] secure_seq: use the 64 bits of the siphash for port offset calculation

Greg Kroah-Hartman
2022-06-23T17:16:42Z

From: Willy Tarreau <w@1wt.eu>

commit b2d057560b8107c633b39aabe517ff9d93f285e3 upstream.

SipHash replaced MD5 in secure_ipv{4,6}_port_ephemeral() via commit
7cd23e5300c1 ("secure_seq: use SipHash in place of MD5"), but the output
remained truncated to 32-bit only. In order to exploit more bits from the
hash, let's make the functions return the full 64-bit of siphash_3u32().
We also make sure the port offset calculation in __inet_hash_connect()
remains done on 32-bit to avoid the need for div_u64_rem() and an extra
cost on 32-bit systems.

Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Moshe Kol <moshe.kol@mail.huji.ac.il>
Cc: Yossi Gilad <yossi.gilad@mail.huji.ac.il>
Cc: Amit Klein <aksecurity@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/inet_hashtables.h | 2 +-
include/net/secure_seq.h | 4 ++--
net/core/secure_seq.c | 4 ++--
net/ipv4/inet_hashtables.c | 10 ++++++----
net/ipv6/inet6_hashtables.c | 4 ++--
5 files changed, 13 insertions(+), 11 deletions(-)

--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -382,7 +382,7 @@ static inline void sk_rcv_saddr_set(stru
}

int __inet_hash_connect(struct inet_timewait_death_row *death_row,
- struct sock *sk, u32 port_offset,
+ struct sock *sk, u64 port_offset,
int (*check_established)(struct inet_timewait_death_row *,
struct sock *, __u16,
struct inet_timewait_sock **));
--- a/include/net/secure_seq.h
+++ b/include/net/secure_seq.h
@@ -3,8 +3,8 @@

#include <linux/types.h>

-u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport);
-u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
+u64 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport);
+u64 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
__be16 dport);
__u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport);
--- a/net/core/secure_seq.c
+++ b/net/core/secure_seq.c
@@ -62,7 +62,7 @@ __u32 secure_tcpv6_sequence_number(const
}
EXPORT_SYMBOL(secure_tcpv6_sequence_number);

-u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
+u64 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
__be16 dport)
{
u32 secret[MD5_MESSAGE_BYTES / 4];
@@ -102,7 +102,7 @@ __u32 secure_tcp_sequence_number(__be32
return seq_scale(hash[0]);
}

-u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
+u64 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
{
u32 hash[MD5_DIGEST_WORDS];

--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -382,7 +382,7 @@ not_unique:
return -EADDRNOTAVAIL;
}

-static u32 inet_sk_port_offset(const struct sock *sk)
+static u64 inet_sk_port_offset(const struct sock *sk)
{
const struct inet_sock *inet = inet_sk(sk);

@@ -549,7 +549,7 @@ EXPORT_SYMBOL_GPL(inet_unhash);
static u32 table_perturb[1 << INET_TABLE_PERTURB_SHIFT];

int __inet_hash_connect(struct inet_timewait_death_row *death_row,
- struct sock *sk, u32 port_offset,
+ struct sock *sk, u64 port_offset,
int (*check_established)(struct inet_timewait_death_row *,
struct sock *, __u16, struct inet_timewait_sock **))
{
@@ -589,7 +589,9 @@ int __inet_hash_connect(struct inet_time
net_get_random_once(table_perturb, sizeof(table_perturb));
index = hash_32(port_offset, INET_TABLE_PERTURB_SHIFT);

- offset = (READ_ONCE(table_perturb[index]) + port_offset) % remaining;
+ offset = READ_ONCE(table_perturb[index]) + port_offset;
+ offset %= remaining;
+
/* In first pass we try ports of @low parity.
* inet_csk_get_port() does the opposite choice.
*/
@@ -670,7 +672,7 @@ ok:
int inet_hash_connect(struct inet_timewait_death_row *death_row,
struct sock *sk)
{
- u32 port_offset = 0;
+ u64 port_offset = 0;

if (!inet_sk(sk)->inet_num)
port_offset = inet_sk_port_offset(sk);
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -242,7 +242,7 @@ not_unique:
return -EADDRNOTAVAIL;
}

-static u32 inet6_sk_port_offset(const struct sock *sk)
+static u64 inet6_sk_port_offset(const struct sock *sk)
{
const struct inet_sock *inet = inet_sk(sk);

@@ -254,7 +254,7 @@ static u32 inet6_sk_port_offset(const st
int inet6_hash_connect(struct inet_timewait_death_row *death_row,
struct sock *sk)
{
- u32 port_offset = 0;
+ u64 port_offset = 0;

if (!inet_sk(sk)->inet_num)
port_offset = inet6_sk_port_offset(sk);