secure_seq: use the 64 bits of the siphash for port offset calculation

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>

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index f72ec113ae568a93b31d0fa415f0e94a26fe94d5..98e1ec1a14f0382d1f4f8e85fe5ac2a056d2d6bc 100644 (file)
--- 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 d7d2495f83c27cc6707fed26f8e433dd6d1eb295..dac91aa38c5af389648e84971b0ad17947ef844c 100644 (file)
--- 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 9b8443774449f5bb8cd2c62ca34eedf139eeb3ed..55aa5cc258e3b83c0b7629dfe37c1e1dbca8b60a 100644 (file)
--- 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 17440840a7914d76c6de91baea5ba94622a051f8..9d24d9319f3dce1850ecb86a54e150688fe913b8 100644 (file)
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -504,7 +504,7 @@ 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);
 
@@ -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 @@ 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);

diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 4740afecf7c6291360d969569771235c8af8b1d1..32ccac10bd625bce956f3ec6d636910722f28656 100644 (file)
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -308,7 +308,7 @@ 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);
 
@@ -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);