New ep's auth_hmacs should be set if old ep's is set, in case that
net->sctp.auth_enable has been changed to 0 by users and new ep's
auth_hmacs couldn't be set in sctp_endpoint_init().
It can even crash kernel by doing:
1. on server: sysctl -w net.sctp.auth_enable=1,
sysctl -w net.sctp.addip_enable=1,
sysctl -w net.sctp.addip_noauth_enable=0,
listen() on server,
sysctl -w net.sctp.auth_enable=0.
2. on client: connect() to server.
3. on server: accept() the asoc,
sysctl -w net.sctp.auth_enable=1.
4. on client: send() asconf packet to server.
The call trace:
[ 245.280251] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[ 245.286872] RIP: 0010:sctp_auth_calculate_hmac+0xa3/0x140 [sctp]
[ 245.304572] Call Trace:
[ 245.305091] <IRQ>
[ 245.311287] sctp_sf_authenticate+0x110/0x160 [sctp]
[ 245.312311] sctp_sf_eat_auth+0xf2/0x230 [sctp]
[ 245.313249] sctp_do_sm+0x9a/0x2d0 [sctp]
[ 245.321483] sctp_assoc_bh_rcv+0xed/0x1a0 [sctp]
[ 245.322495] sctp_rcv+0xa66/0xc70 [sctp]
It's because the old ep->auth_hmacs wasn't copied to the new ep while
ep->auth_hmacs is used in sctp_auth_calculate_hmac() when processing
the incoming auth chunks, and it should have been done when migrating
sock.
Reported-by: Ying Xu <yinxu@xxxxxxxxxx>
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
---
net/sctp/socket.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 22adb8d..def3335 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -8978,6 +8978,16 @@ static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
if (err)
return err;
+ /* New ep's auth_hmacs should be set if old ep's is set, in case
+ * that net->sctp.auth_enable has been changed to 0 by users and
+ * new ep's auth_hmacs couldn't be set in sctp_endpoint_init().
+ */
+ if (oldsp->ep->auth_hmacs) {
+ err = sctp_auth_init_hmacs(newsp->ep, GFP_KERNEL);
+ if (err)
+ return err;
+ }
+
/* Move any messages in the old socket's receive queue that are for the
* peeled off association to the new socket's receive queue.
*/
--
2.1.0
