diff options
Diffstat (limited to 'Documentation/networking/rxrpc.txt')
| -rw-r--r-- | Documentation/networking/rxrpc.txt | 168 |
1 files changed, 159 insertions, 9 deletions
diff --git a/Documentation/networking/rxrpc.txt b/Documentation/networking/rxrpc.txt index 1b63bbc6b94f..810620153a44 100644 --- a/Documentation/networking/rxrpc.txt +++ b/Documentation/networking/rxrpc.txt @@ -325,6 +325,9 @@ calls, to invoke certain actions and to report certain conditions. These are: RXRPC_LOCAL_ERROR -rt error num Local error encountered RXRPC_NEW_CALL -r- n/a New call received RXRPC_ACCEPT s-- n/a Accept new call + RXRPC_EXCLUSIVE_CALL s-- n/a Make an exclusive client call + RXRPC_UPGRADE_SERVICE s-- n/a Client call can be upgraded + RXRPC_TX_LENGTH s-- data len Total length of Tx data (SRT = usable in Sendmsg / delivered by Recvmsg / Terminal message) @@ -387,6 +390,40 @@ calls, to invoke certain actions and to report certain conditions. These are: return error ENODATA. If the user ID is already in use by another call, then error EBADSLT will be returned. + (*) RXRPC_EXCLUSIVE_CALL + + This is used to indicate that a client call should be made on a one-off + connection. The connection is discarded once the call has terminated. + + (*) RXRPC_UPGRADE_SERVICE + + This is used to make a client call to probe if the specified service ID + may be upgraded by the server. The caller must check msg_name returned to + recvmsg() for the service ID actually in use. The operation probed must + be one that takes the same arguments in both services. + + Once this has been used to establish the upgrade capability (or lack + thereof) of the server, the service ID returned should be used for all + future communication to that server and RXRPC_UPGRADE_SERVICE should no + longer be set. + + (*) RXRPC_TX_LENGTH + + This is used to inform the kernel of the total amount of data that is + going to be transmitted by a call (whether in a client request or a + service response). If given, it allows the kernel to encrypt from the + userspace buffer directly to the packet buffers, rather than copying into + the buffer and then encrypting in place. This may only be given with the + first sendmsg() providing data for a call. EMSGSIZE will be generated if + the amount of data actually given is different. + + This takes a parameter of __s64 type that indicates how much will be + transmitted. This may not be less than zero. + +The symbol RXRPC__SUPPORTED is defined as one more than the highest control +message type supported. At run time this can be queried by means of the +RXRPC_SUPPORTED_CMSG socket option (see below). + ============== SOCKET OPTIONS @@ -433,6 +470,18 @@ AF_RXRPC sockets support a few socket options at the SOL_RXRPC level: Encrypted checksum plus entire packet padded and encrypted, including actual packet length. + (*) RXRPC_UPGRADEABLE_SERVICE + + This is used to indicate that a service socket with two bindings may + upgrade one bound service to the other if requested by the client. optval + must point to an array of two unsigned short ints. The first is the + service ID to upgrade from and the second the service ID to upgrade to. + + (*) RXRPC_SUPPORTED_CMSG + + This is a read-only option that writes an int into the buffer indicating + the highest control message type supported. + ======== SECURITY @@ -542,6 +591,9 @@ A client would issue an operation by: MSG_MORE should be set in msghdr::msg_flags on all but the last part of the request. Multiple requests may be made simultaneously. + An RXRPC_TX_LENGTH control message can also be specified on the first + sendmsg() call. + If a call is intended to go to a destination other than the default specified through connect(), then msghdr::msg_name should be set on the first request message of that call. @@ -559,6 +611,17 @@ A client would issue an operation by: buffer instead, and MSG_EOR will be flagged to indicate the end of that call. +A client may ask for a service ID it knows and ask that this be upgraded to a +better service if one is available by supplying RXRPC_UPGRADE_SERVICE on the +first sendmsg() of a call. The client should then check srx_service in the +msg_name filled in by recvmsg() when collecting the result. srx_service will +hold the same value as given to sendmsg() if the upgrade request was ignored by +the service - otherwise it will be altered to indicate the service ID the +server upgraded to. Note that the upgraded service ID is chosen by the server. +The caller has to wait until it sees the service ID in the reply before sending +any more calls (further calls to the same destination will be blocked until the +probe is concluded). + ==================== EXAMPLE SERVER USAGE @@ -588,7 +651,7 @@ A server would be set up to accept operations in the following manner: The keyring can be manipulated after it has been given to the socket. This permits the server to add more keys, replace keys, etc. whilst it is live. - (2) A local address must then be bound: + (3) A local address must then be bound: struct sockaddr_rxrpc srx = { .srx_family = AF_RXRPC, @@ -600,11 +663,26 @@ A server would be set up to accept operations in the following manner: }; bind(server, &srx, sizeof(srx)); - (3) The server is then set to listen out for incoming calls: + More than one service ID may be bound to a socket, provided the transport + parameters are the same. The limit is currently two. To do this, bind() + should be called twice. + + (4) If service upgrading is required, first two service IDs must have been + bound and then the following option must be set: + + unsigned short service_ids[2] = { from_ID, to_ID }; + setsockopt(server, SOL_RXRPC, RXRPC_UPGRADEABLE_SERVICE, + service_ids, sizeof(service_ids)); + + This will automatically upgrade connections on service from_ID to service + to_ID if they request it. This will be reflected in msg_name obtained + through recvmsg() when the request data is delivered to userspace. + + (5) The server is then set to listen out for incoming calls: listen(server, 100); - (4) The kernel notifies the server of pending incoming connections by sending + (6) The kernel notifies the server of pending incoming connections by sending it a message for each. This is received with recvmsg() on the server socket. It has no data, and has a single dataless control message attached: @@ -616,13 +694,13 @@ A server would be set up to accept operations in the following manner: the time it is accepted - in which case the first call still on the queue will be accepted. - (5) The server then accepts the new call by issuing a sendmsg() with two + (7) The server then accepts the new call by issuing a sendmsg() with two pieces of control data and no actual data: RXRPC_ACCEPT - indicate connection acceptance RXRPC_USER_CALL_ID - specify user ID for this call - (6) The first request data packet will then be posted to the server socket for + (8) The first request data packet will then be posted to the server socket for recvmsg() to pick up. At that point, the RxRPC address for the call can be read from the address fields in the msghdr struct. @@ -634,7 +712,7 @@ A server would be set up to accept operations in the following manner: RXRPC_USER_CALL_ID - specifies the user ID for this call - (8) The reply data should then be posted to the server socket using a series + (9) The reply data should then be posted to the server socket using a series of sendmsg() calls, each with the following control messages attached: RXRPC_USER_CALL_ID - specifies the user ID for this call @@ -642,7 +720,7 @@ A server would be set up to accept operations in the following manner: MSG_MORE should be set in msghdr::msg_flags on all but the last message for a particular call. - (9) The final ACK from the client will be posted for retrieval by recvmsg() +(10) The final ACK from the client will be posted for retrieval by recvmsg() when it is received. It will take the form of a dataless message with two control messages attached: @@ -652,7 +730,7 @@ A server would be set up to accept operations in the following manner: MSG_EOR will be flagged to indicate that this is the final message for this call. -(10) Up to the point the final packet of reply data is sent, the call can be +(11) Up to the point the final packet of reply data is sent, the call can be aborted by calling sendmsg() with a dataless message with the following control messages attached: @@ -703,6 +781,7 @@ The kernel interface functions are as follows: struct sockaddr_rxrpc *srx, struct key *key, unsigned long user_call_ID, + s64 tx_total_len, gfp_t gfp); This allocates the infrastructure to make a new RxRPC call and assigns @@ -719,6 +798,11 @@ The kernel interface functions are as follows: control data buffer. It is entirely feasible to use this to point to a kernel data structure. + tx_total_len is the amount of data the caller is intending to transmit + with this call (or -1 if unknown at this point). Setting the data size + allows the kernel to encrypt directly to the packet buffers, thereby + saving a copy. The value may not be less than -1. + If this function is successful, an opaque reference to the RxRPC call is returned. The caller now holds a reference on this and it must be properly ended. @@ -734,10 +818,15 @@ The kernel interface functions are as follows: (*) Send data through a call. + typedef void (*rxrpc_notify_end_tx_t)(struct sock *sk, + unsigned long user_call_ID, + struct sk_buff *skb); + int rxrpc_kernel_send_data(struct socket *sock, struct rxrpc_call *call, struct msghdr *msg, - size_t len); + size_t len, + rxrpc_notify_end_tx_t notify_end_rx); This is used to supply either the request part of a client call or the reply part of a server call. msg.msg_iovlen and msg.msg_iov specify the @@ -748,6 +837,11 @@ The kernel interface functions are as follows: The msg must not specify a destination address, control data or any flags other than MSG_MORE. len is the total amount of data to transmit. + notify_end_rx can be NULL or it can be used to specify a function to be + called when the call changes state to end the Tx phase. This function is + called with the call-state spinlock held to prevent any reply or final ACK + from being delivered first. + (*) Receive data from a call. int rxrpc_kernel_recv_data(struct socket *sock, @@ -870,6 +964,62 @@ The kernel interface functions are as follows: This is used to find the remote peer address of a call. + (*) Set the total transmit data size on a call. + + void rxrpc_kernel_set_tx_length(struct socket *sock, + struct rxrpc_call *call, + s64 tx_total_len); + + This sets the amount of data that the caller is intending to transmit on a + call. It's intended to be used for setting the reply size as the request + size should be set when the call is begun. tx_total_len may not be less + than zero. + + (*) Check to see the completion state of a call so that the caller can assess + whether it needs to be retried. + + enum rxrpc_call_completion { + RXRPC_CALL_SUCCEEDED, + RXRPC_CALL_REMOTELY_ABORTED, + RXRPC_CALL_LOCALLY_ABORTED, + RXRPC_CALL_LOCAL_ERROR, + RXRPC_CALL_NETWORK_ERROR, + }; + + int rxrpc_kernel_check_call(struct socket *sock, struct rxrpc_call *call, + enum rxrpc_call_completion *_compl, + u32 *_abort_code); + + On return, -EINPROGRESS will be returned if the call is still ongoing; if + it is finished, *_compl will be set to indicate the manner of completion, + *_abort_code will be set to any abort code that occurred. 0 will be + returned on a successful completion, -ECONNABORTED will be returned if the + client failed due to a remote abort and anything else will return an + appropriate error code. + + The caller should look at this information to decide if it's worth + retrying the call. + + (*) Retry a client call. + + int rxrpc_kernel_retry_call(struct socket *sock, + struct rxrpc_call *call, + struct sockaddr_rxrpc *srx, + struct key *key); + + This attempts to partially reinitialise a call and submit it again whilst + reusing the original call's Tx queue to avoid the need to repackage and + re-encrypt the data to be sent. call indicates the call to retry, srx the + new address to send it to and key the encryption key to use for signing or + encrypting the packets. + + For this to work, the first Tx data packet must still be in the transmit + queue, and currently this is only permitted for local and network errors + and the call must not have been aborted. Any partially constructed Tx + packet is left as is and can continue being filled afterwards. + + It returns 0 if the call was requeued and an error otherwise. + ======================= CONFIGURABLE PARAMETERS |