tcp: dynamically allocate the perturb table used by source ports

[ Upstream commit e9261476184be1abd486c9434164b2acbe0ed6c2 ]

We'll need to further increase the size of this table and it's likely
that at some point its size will not be suitable anymore for a static
table. Let's allocate it on boot from inet_hashinfo2_init(), which is
called from tcp_init().

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: Sasha Levin <sashal@kernel.org>

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 573a7e6..763395e 100644 (file)
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -731,7 +731,8 @@ EXPORT_SYMBOL_GPL(inet_unhash);
  * privacy, this only consumes 1 KB of kernel memory.
  */
 #define INET_TABLE_PERTURB_SHIFT 8
-static u32 table_perturb[1 << INET_TABLE_PERTURB_SHIFT];
+#define INET_TABLE_PERTURB_SIZE (1 << INET_TABLE_PERTURB_SHIFT)
+static u32 *table_perturb;
 
 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
                struct sock *sk, u64 port_offset,
@@ -774,7 +775,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
        if (likely(remaining > 1))
                remaining &= ~1U;
 
-       net_get_random_once(table_perturb, sizeof(table_perturb));
+       net_get_random_once(table_perturb,
+                           INET_TABLE_PERTURB_SIZE * sizeof(*table_perturb));
        index = hash_32(port_offset, INET_TABLE_PERTURB_SHIFT);
 
        offset = READ_ONCE(table_perturb[index]) + (port_offset >> 32);
@@ -912,6 +914,12 @@ void __init inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
                                            low_limit,
                                            high_limit);
        init_hashinfo_lhash2(h);
+
+       /* this one is used for source ports of outgoing connections */
+       table_perturb = kmalloc_array(INET_TABLE_PERTURB_SIZE,
+                                     sizeof(*table_perturb), GFP_KERNEL);
+       if (!table_perturb)
+               panic("TCP: failed to alloc table_perturb");
 }
 
 int inet_hashinfo2_init_mod(struct inet_hashinfo *h)