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Subject[PATCH 4.14 235/237] tcp: dynamically allocate the perturb table used by source ports
Date
From: Willy Tarreau <w@1wt.eu>

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 4.14:
- 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>
---
net/ipv4/inet_hashtables.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -596,7 +596,8 @@ 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,
@@ -636,7 +637,8 @@ int __inet_hash_connect(struct inet_time
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);
@@ -741,6 +743,15 @@ void inet_hashinfo_init(struct inet_hash
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);


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