tcp: dynamically allocate the perturb table used by source ports

commit e9261476184be1abd486c9434164b2acbe0ed6c2 upstream.

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>
[bwh: Backported to 4.19: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index f6581e5b03271af59705eddb1b67ecf852a5f58f..f85632a1a006934f0a6440e1b75cc56afa2d05a5 100644 (file)
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -723,7 +723,8 @@ 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,
@@ -763,7 +764,8 @@ 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);
@@ -896,6 +898,12 @@ void __init inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
                INIT_HLIST_HEAD(&h->lhash2[i].head);
                h->lhash2[i].count = 0;
        }
+
+       /* 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_ehash_locks_alloc(struct inet_hashinfo *hashinfo)