From: Willy Tarreau <w@1wt.eu>
Date: Mon, 2 May 2022 10:46:12 +0200
Subject: tcp: dynamically allocate the perturb table used by source ports
Patch-mainline: v5.18-rc6
Git-commit: e9261476184be1abd486c9434164b2acbe0ed6c2
References: CVE-2022-1012 CVE-2022-32296 bsc#1199482 bsc#1200288

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>
Acked-by: Michal Kubecek <mkubecek@suse.cz>

SLE12-SP5: we do not have inet_hashinfo2_init() in SLE12-SP5 code and
cannot use inet_hashinfo_init() which is also called from DCCP code. Create
a separate function inet_alloc_perturb_table() for perturb table allocation
instead.

---
 include/net/inet_hashtables.h |  1 +
 net/ipv4/inet_hashtables.c    | 15 +++++++++++++--
 net/ipv4/tcp.c                |  1 +
 3 files changed, 15 insertions(+), 2 deletions(-)

--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -208,6 +208,7 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child);
 void inet_put_port(struct sock *sk);
 
 void inet_hashinfo_init(struct inet_hashinfo *h);
+void inet_alloc_perturb_table(void);
 
 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk);
 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk,
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -589,7 +589,8 @@ 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,
@@ -629,7 +630,8 @@ 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);
@@ -736,6 +738,15 @@ void inet_hashinfo_init(struct inet_hashinfo *h)
 }
 EXPORT_SYMBOL_GPL(inet_hashinfo_init);
 
+void __init inet_alloc_perturb_table(void)
+{
+	/* 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)
 {
 	unsigned int locksz = sizeof(spinlock_t);
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3428,6 +3428,7 @@ void __init tcp_init(void)
 	percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL);
 	percpu_counter_init(&tcp_orphan_count, 0, GFP_KERNEL);
 	inet_hashinfo_init(&tcp_hashinfo);
+	inet_alloc_perturb_table();
 	tcp_hashinfo.bind_bucket_cachep =
 		kmem_cache_create("tcp_bind_bucket",
 				  sizeof(struct inet_bind_bucket), 0,