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Subject[PATCH v3 net 1/7] secure_seq: use the 64 bits of the siphash for port offset calculation
Date
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>
---
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(-)

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index f72ec113ae56..98e1ec1a14f0 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -425,7 +425,7 @@ static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
}

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 **));
diff --git a/include/net/secure_seq.h b/include/net/secure_seq.h
index d7d2495f83c2..dac91aa38c5a 100644
--- a/include/net/secure_seq.h
+++ b/include/net/secure_seq.h
@@ -4,8 +4,8 @@

#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_seq(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport);
diff --git a/net/core/secure_seq.c b/net/core/secure_seq.c
index 9b8443774449..55aa5cc258e3 100644
--- a/net/core/secure_seq.c
+++ b/net/core/secure_seq.c
@@ -94,7 +94,7 @@ u32 secure_tcpv6_seq(const __be32 *saddr, const __be32 *daddr,
}
EXPORT_SYMBOL(secure_tcpv6_seq);

-u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
+u64 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
__be16 dport)
{
const struct {
@@ -142,7 +142,7 @@ u32 secure_tcp_seq(__be32 saddr, __be32 daddr,
}
EXPORT_SYMBOL_GPL(secure_tcp_seq);

-u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
+u64 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
{
net_secret_init();
return siphash_3u32((__force u32)saddr, (__force u32)daddr,
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 17440840a791..9d24d9319f3d 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -504,7 +504,7 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row,
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);

@@ -734,7 +734,7 @@ 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 **))
{
@@ -777,7 +777,9 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
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.
*/
@@ -859,7 +861,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
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);
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 4740afecf7c6..32ccac10bd62 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -308,7 +308,7 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row,
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);

@@ -320,7 +320,7 @@ static u32 inet6_sk_port_offset(const struct sock *sk)
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);
--
2.17.5
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