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[PATCH net-next 4/9] rxrpc: Randomise epoch and starting client conn ID values

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Create a random epoch value rather than a time-based one on startup and set
the top bit to indicate that this is the case.

Also create a random starting client connection ID value.  This will be
incremented from here as new client connections are created.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 include/rxrpc/packet.h |    1 +
 net/rxrpc/af_rxrpc.c   |    9 ++++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/rxrpc/packet.h b/include/rxrpc/packet.h
index b2017440b765..3c6128e1fdbe 100644
--- a/include/rxrpc/packet.h
+++ b/include/rxrpc/packet.h
@@ -24,6 +24,7 @@ typedef __be32	rxrpc_serial_net_t; /* on-the-wire Rx message serial number */
  */
 struct rxrpc_wire_header {
 	__be32		epoch;		/* client boot timestamp */
+#define RXRPC_RANDOM_EPOCH	0x80000000	/* Random if set, date-based if not */
 
 	__be32		cid;		/* connection and channel ID */
 #define RXRPC_MAXCALLS		4			/* max active calls per conn */
diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index 32d544995dda..b66a9e6f8d04 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -16,6 +16,7 @@
 #include <linux/net.h>
 #include <linux/slab.h>
 #include <linux/skbuff.h>
+#include <linux/random.h>
 #include <linux/poll.h>
 #include <linux/proc_fs.h>
 #include <linux/key-type.h>
@@ -700,7 +701,13 @@ static int __init af_rxrpc_init(void)
 
 	BUILD_BUG_ON(sizeof(struct rxrpc_skb_priv) > FIELD_SIZEOF(struct sk_buff, cb));
 
-	rxrpc_epoch = get_seconds();
+	get_random_bytes(&rxrpc_epoch, sizeof(rxrpc_epoch));
+	rxrpc_epoch |= RXRPC_RANDOM_EPOCH;
+	get_random_bytes(&rxrpc_client_conn_ids.cur,
+			 sizeof(rxrpc_client_conn_ids.cur));
+	rxrpc_client_conn_ids.cur &= 0x3fffffff;
+	if (rxrpc_client_conn_ids.cur == 0)
+		rxrpc_client_conn_ids.cur = 1;
 
 	ret = -ENOMEM;
 	rxrpc_call_jar = kmem_cache_create(

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Thread

[PATCH net-next 0/9] rxrpc: Small fixes David Howells <dhowells@redhat.com> - 2016-09-04 23:10 +0200
  [PATCH net-next 9/9] fs/afs/flock: Remove deprecated  create_singlethread_workqueue David Howells <dhowells@redhat.com> - 2016-09-04 23:10 +0200
  [PATCH net-next 5/9] rxrpc: Don't change the epoch David Howells <dhowells@redhat.com> - 2016-09-04 23:10 +0200
  [PATCH net-next 6/9] fs/afs/vlocation: Remove deprecated  create_singlethread_workqueue David Howells <dhowells@redhat.com> - 2016-09-04 23:20 +0200
  [PATCH net-next 3/9] rxrpc: The client call state must be changed  before attachment to conn David Howells <dhowells@redhat.com> - 2016-09-04 23:20 +0200
  [PATCH net-next 4/9] rxrpc: Randomise epoch and starting client  conn ID values David Howells <dhowells@redhat.com> - 2016-09-04 23:20 +0200
    RE: [PATCH net-next 4/9] rxrpc: Randomise epoch and starting client  conn ID values David Laight <David.Laight@ACULAB.COM> - 2016-09-05 17:10 +0200
      Re: [PATCH net-next 4/9] rxrpc: Randomise epoch and starting client conn ID values David Howells <dhowells@redhat.com> - 2016-09-05 18:30 +0200
        Re: [PATCH net-next 4/9] rxrpc: Randomise epoch and starting client  conn ID values Jeffrey Altman <jaltman@auristor.com> - 2016-09-06 04:20 +0200
  [PATCH net-next 7/9] fs/afs/rxrpc: Remove deprecated  create_singlethread_workqueue David Howells <dhowells@redhat.com> - 2016-09-04 23:20 +0200
  [PATCH net-next 8/9] fs/afs/callback: Remove deprecated  create_singlethread_workqueue David Howells <dhowells@redhat.com> - 2016-09-04 23:20 +0200
  Re: [PATCH net-next 0/9] rxrpc: Small fixes David Miller <davem@davemloft.net> - 2016-09-06 23:00 +0200

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