From 41b996ce83bf944de5569d6263c8dbd5513e7ed0 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 4 Feb 2025 23:05:53 +0000 Subject: [PATCH 1/2] rxrpc: Fix call state set to not include the SERVER_SECURING state The RXRPC_CALL_SERVER_SECURING state doesn't really belong with the other states in the call's state set as the other states govern the call's Rx/Tx phase transition and govern when packets can and can't be received or transmitted. The "Securing" state doesn't actually govern the reception of packets and would need to be split depending on whether or not we've received the last packet yet (to mirror RECV_REQUEST/ACK_REQUEST). The "Securing" state is more about whether or not we can start forwarding packets to the application as recvmsg will need to decode them and the decoding can't take place until the challenge/response exchange has completed. Fix this by removing the RXRPC_CALL_SERVER_SECURING state from the state set and, instead, using a flag, RXRPC_CALL_CONN_CHALLENGING, to track whether or not we can queue the call for reception by recvmsg() or notify the kernel app that data is ready. In the event that we've already received all the packets, the connection event handler will poke the app layer in the appropriate manner. Also there's a race whereby the app layer sees the last packet before rxrpc has managed to end the rx phase and change the state to one amenable to allowing a reply. Fix this by queuing the packet after calling rxrpc_end_rx_phase(). Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both") Signed-off-by: David Howells cc: Marc Dionne cc: Simon Horman cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20250204230558.712536-2-dhowells@redhat.com Signed-off-by: Jakub Kicinski --- net/rxrpc/ar-internal.h | 2 +- net/rxrpc/call_object.c | 6 ++---- net/rxrpc/conn_event.c | 4 +--- net/rxrpc/input.c | 2 +- net/rxrpc/sendmsg.c | 2 +- 5 files changed, 6 insertions(+), 10 deletions(-) diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 718193df9d2e2..f251845fe532c 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -582,6 +582,7 @@ enum rxrpc_call_flag { RXRPC_CALL_EXCLUSIVE, /* The call uses a once-only connection */ RXRPC_CALL_RX_IS_IDLE, /* recvmsg() is idle - send an ACK */ RXRPC_CALL_RECVMSG_READ_ALL, /* recvmsg() read all of the received data */ + RXRPC_CALL_CONN_CHALLENGING, /* The connection is being challenged */ }; /* @@ -602,7 +603,6 @@ enum rxrpc_call_state { RXRPC_CALL_CLIENT_AWAIT_REPLY, /* - client awaiting reply */ RXRPC_CALL_CLIENT_RECV_REPLY, /* - client receiving reply phase */ RXRPC_CALL_SERVER_PREALLOC, /* - service preallocation */ - RXRPC_CALL_SERVER_SECURING, /* - server securing request connection */ RXRPC_CALL_SERVER_RECV_REQUEST, /* - server receiving request */ RXRPC_CALL_SERVER_ACK_REQUEST, /* - server pending ACK of request */ RXRPC_CALL_SERVER_SEND_REPLY, /* - server sending reply */ diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c index 5a543c3f6fb08..c4c8b46a68c67 100644 --- a/net/rxrpc/call_object.c +++ b/net/rxrpc/call_object.c @@ -22,7 +22,6 @@ const char *const rxrpc_call_states[NR__RXRPC_CALL_STATES] = { [RXRPC_CALL_CLIENT_AWAIT_REPLY] = "ClAwtRpl", [RXRPC_CALL_CLIENT_RECV_REPLY] = "ClRcvRpl", [RXRPC_CALL_SERVER_PREALLOC] = "SvPrealc", - [RXRPC_CALL_SERVER_SECURING] = "SvSecure", [RXRPC_CALL_SERVER_RECV_REQUEST] = "SvRcvReq", [RXRPC_CALL_SERVER_ACK_REQUEST] = "SvAckReq", [RXRPC_CALL_SERVER_SEND_REPLY] = "SvSndRpl", @@ -453,17 +452,16 @@ void rxrpc_incoming_call(struct rxrpc_sock *rx, call->cong_tstamp = skb->tstamp; __set_bit(RXRPC_CALL_EXPOSED, &call->flags); - rxrpc_set_call_state(call, RXRPC_CALL_SERVER_SECURING); + rxrpc_set_call_state(call, RXRPC_CALL_SERVER_RECV_REQUEST); spin_lock(&conn->state_lock); switch (conn->state) { case RXRPC_CONN_SERVICE_UNSECURED: case RXRPC_CONN_SERVICE_CHALLENGING: - rxrpc_set_call_state(call, RXRPC_CALL_SERVER_SECURING); + __set_bit(RXRPC_CALL_CONN_CHALLENGING, &call->flags); break; case RXRPC_CONN_SERVICE: - rxrpc_set_call_state(call, RXRPC_CALL_SERVER_RECV_REQUEST); break; case RXRPC_CONN_ABORTED: diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c index 74bb49b936cd4..4d9c5e21ba785 100644 --- a/net/rxrpc/conn_event.c +++ b/net/rxrpc/conn_event.c @@ -228,10 +228,8 @@ static void rxrpc_abort_calls(struct rxrpc_connection *conn) */ static void rxrpc_call_is_secure(struct rxrpc_call *call) { - if (call && __rxrpc_call_state(call) == RXRPC_CALL_SERVER_SECURING) { - rxrpc_set_call_state(call, RXRPC_CALL_SERVER_RECV_REQUEST); + if (call && __test_and_clear_bit(RXRPC_CALL_CONN_CHALLENGING, &call->flags)) rxrpc_notify_socket(call); - } } /* diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c index 4974b5accafa3..4a152f3c831fd 100644 --- a/net/rxrpc/input.c +++ b/net/rxrpc/input.c @@ -657,7 +657,7 @@ static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb rxrpc_propose_delay_ACK(call, sp->hdr.serial, rxrpc_propose_ack_input_data); } - if (notify) { + if (notify && !test_bit(RXRPC_CALL_CONN_CHALLENGING, &call->flags)) { trace_rxrpc_notify_socket(call->debug_id, sp->hdr.serial); rxrpc_notify_socket(call); } diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c index 0e8da909d4f2f..584397aba4a07 100644 --- a/net/rxrpc/sendmsg.c +++ b/net/rxrpc/sendmsg.c @@ -707,7 +707,7 @@ int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len) } else { switch (rxrpc_call_state(call)) { case RXRPC_CALL_CLIENT_AWAIT_CONN: - case RXRPC_CALL_SERVER_SECURING: + case RXRPC_CALL_SERVER_RECV_REQUEST: if (p.command == RXRPC_CMD_SEND_ABORT) break; fallthrough; From 2d7b30aef34dae942e9ab7812b288ce14658ae66 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 4 Feb 2025 23:05:54 +0000 Subject: [PATCH 2/2] rxrpc: Fix race in call state changing vs recvmsg() There's a race in between the rxrpc I/O thread recording the end of the receive phase of a call and recvmsg() examining the state of the call to determine whether it has completed. The problem is that call->_state records the I/O thread's view of the call, not the application's view (which may lag), so that alone is not sufficient. To this end, the application also checks whether there is anything left in call->recvmsg_queue for it to pick up. The call must be in state RXRPC_CALL_COMPLETE and the recvmsg_queue empty for the call to be considered fully complete. In rxrpc_input_queue_data(), the latest skbuff is added to the queue and then, if it was marked as LAST_PACKET, the state is advanced... But this is two separate operations with no locking around them. As a consequence, the lack of locking means that sendmsg() can jump into the gap on a service call and attempt to send the reply - but then get rejected because the I/O thread hasn't advanced the state yet. Simply flipping the order in which things are done isn't an option as that impacts the client side, causing the checks in rxrpc_kernel_check_life() as to whether the call is still alive to race instead. Fix this by moving the update of call->_state inside the skb queue spinlocked section where the packet is queued on the I/O thread side. rxrpc's recvmsg() will then automatically sync against this because it has to take the call->recvmsg_queue spinlock in order to dequeue the last packet. rxrpc's sendmsg() doesn't need amending as the app shouldn't be calling it to send a reply until recvmsg() indicates it has returned all of the request. Fixes: 93368b6bd58a ("rxrpc: Move call state changes from recvmsg to I/O thread") Signed-off-by: David Howells cc: Marc Dionne cc: Simon Horman cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20250204230558.712536-3-dhowells@redhat.com Signed-off-by: Jakub Kicinski --- net/rxrpc/input.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c index 4a152f3c831fd..9047ba13bd31e 100644 --- a/net/rxrpc/input.c +++ b/net/rxrpc/input.c @@ -448,11 +448,19 @@ static void rxrpc_input_queue_data(struct rxrpc_call *call, struct sk_buff *skb, struct rxrpc_skb_priv *sp = rxrpc_skb(skb); bool last = sp->hdr.flags & RXRPC_LAST_PACKET; - skb_queue_tail(&call->recvmsg_queue, skb); + spin_lock_irq(&call->recvmsg_queue.lock); + + __skb_queue_tail(&call->recvmsg_queue, skb); rxrpc_input_update_ack_window(call, window, wtop); trace_rxrpc_receive(call, last ? why + 1 : why, sp->hdr.serial, sp->hdr.seq); if (last) + /* Change the state inside the lock so that recvmsg syncs + * correctly with it and using sendmsg() to send a reply + * doesn't race. + */ rxrpc_end_rx_phase(call, sp->hdr.serial); + + spin_unlock_irq(&call->recvmsg_queue.lock); } /*