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tcp: dynamically allocate the perturb table used by source ports

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commit e926147618 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 4.9:
 - There is no inet_hashinfo2_init(), so allocate the table in
   inet_hashinfo_init() when called by TCP
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Willy Tarreau
2022-05-02 10:46:12 +02:00
committed by Chris
parent 83248905be
commit f4e508243c
1 changed files with 13 additions and 2 deletions
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15
net/ipv4/inet_hashtables.c
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@@ -546,7 +546,8 @@ 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,
@@ -586,7 +587,8 @@ 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);
@@ -691,6 +693,15 @@ void inet_hashinfo_init(struct inet_hashinfo *h)
INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].nulls_head,
i + LISTENING_NULLS_BASE);
}
if (h != &tcp_hashinfo)
return;
/* 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");
}
EXPORT_SYMBOL_GPL(inet_hashinfo_init);