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rxrpc: Randomise epoch and starting client conn ID values 

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>
This commit is contained in:
David Howells 2016-09-02 22:39:45 +01:00
parent af338a9ea6
commit 5f2d9c4438
2 changed files with 9 additions and 1 deletions
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1
include/rxrpc/packet.h
View File

@ -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 */

9
net/rxrpc/af_rxrpc.c
View File

@ -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(