1. 05 Aug, 2016 1 commit
    • David Howells's avatar
      rxrpc: Fix races between skb free, ACK generation and replying · 372ee163
      David Howells authored
      Inside the kafs filesystem it is possible to occasionally have a call
      processed and terminated before we've had a chance to check whether we need
      to clean up the rx queue for that call because afs_send_simple_reply() ends
      the call when it is done, but this is done in a workqueue item that might
      happen to run to completion before afs_deliver_to_call() completes.
      
      Further, it is possible for rxrpc_kernel_send_data() to be called to send a
      reply before the last request-phase data skb is released.  The rxrpc skb
      destructor is where the ACK processing is done and the call state is
      advanced upon release of the last skb.  ACK generation is also deferred to
      a work item because it's possible that the skb destructor is not called in
      a context where kernel_sendmsg() can be invoked.
      
      To this end, the following changes are made:
      
       (1) kernel_rxrpc_data_consumed() is added.  This should be called whenever
           an skb is emptied so as to crank the ACK and call states.  This does
           not release the skb, however.  kernel_rxrpc_free_skb() must now be
           called to achieve that.  These together replace
           rxrpc_kernel_data_delivered().
      
       (2) kernel_rxrpc_data_consumed() is wrapped by afs_data_consumed().
      
           This makes afs_deliver_to_call() easier to work as the skb can simply
           be discarded unconditionally here without trying to work out what the
           return value of the ->deliver() function means.
      
           The ->deliver() functions can, via afs_data_complete(),
           afs_transfer_reply() and afs_extract_data() mark that an skb has been
           consumed (thereby cranking the state) without the need to
           conditionally free the skb to make sure the state is correct on an
           incoming call for when the call processor tries to send the reply.
      
       (3) rxrpc_recvmsg() now has to call kernel_rxrpc_data_consumed() when it
           has finished with a packet and MSG_PEEK isn't set.
      
       (4) rxrpc_packet_destructor() no longer calls rxrpc_hard_ACK_data().
      
           Because of this, we no longer need to clear the destructor and put the
           call before we free the skb in cases where we don't want the ACK/call
           state to be cranked.
      
       (5) The ->deliver() call-type callbacks are made to return -EAGAIN rather
           than 0 if they expect more data (afs_extract_data() returns -EAGAIN to
           the delivery function already), and the caller is now responsible for
           producing an abort if that was the last packet.
      
       (6) There are many bits of unmarshalling code where:
      
       		ret = afs_extract_data(call, skb, last, ...);
      		switch (ret) {
      		case 0:		break;
      		case -EAGAIN:	return 0;
      		default:	return ret;
      		}
      
           is to be found.  As -EAGAIN can now be passed back to the caller, we
           now just return if ret < 0:
      
       		ret = afs_extract_data(call, skb, last, ...);
      		if (ret < 0)
      			return ret;
      
       (7) Checks for trailing data and empty final data packets has been
           consolidated as afs_data_complete().  So:
      
      		if (skb->len > 0)
      			return -EBADMSG;
      		if (!last)
      			return 0;
      
           becomes:
      
      		ret = afs_data_complete(call, skb, last);
      		if (ret < 0)
      			return ret;
      
       (8) afs_transfer_reply() now checks the amount of data it has against the
           amount of data desired and the amount of data in the skb and returns
           an error to induce an abort if we don't get exactly what we want.
      
      Without these changes, the following oops can occasionally be observed,
      particularly if some printks are inserted into the delivery path:
      
      general protection fault: 0000 [#1] SMP
      Modules linked in: kafs(E) af_rxrpc(E) [last unloaded: af_rxrpc]
      CPU: 0 PID: 1305 Comm: kworker/u8:3 Tainted: G            E   4.7.0-fsdevel+ #1303
      Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
      Workqueue: kafsd afs_async_workfn [kafs]
      task: ffff88040be041c0 ti: ffff88040c070000 task.ti: ffff88040c070000
      RIP: 0010:[<ffffffff8108fd3c>]  [<ffffffff8108fd3c>] __lock_acquire+0xcf/0x15a1
      RSP: 0018:ffff88040c073bc0  EFLAGS: 00010002
      RAX: 6b6b6b6b6b6b6b6b RBX: 0000000000000000 RCX: ffff88040d29a710
      RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88040d29a710
      RBP: ffff88040c073c70 R08: 0000000000000001 R09: 0000000000000001
      R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
      R13: 0000000000000000 R14: ffff88040be041c0 R15: ffffffff814c928f
      FS:  0000000000000000(0000) GS:ffff88041fa00000(0000) knlGS:0000000000000000
      CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      CR2: 00007fa4595f4750 CR3: 0000000001c14000 CR4: 00000000001406f0
      Stack:
       0000000000000006 000000000be04930 0000000000000000 ffff880400000000
       ffff880400000000 ffffffff8108f847 ffff88040be041c0 ffffffff81050446
       ffff8803fc08a920 ffff8803fc08a958 ffff88040be041c0 ffff88040c073c38
      Call Trace:
       [<ffffffff8108f847>] ? mark_held_locks+0x5e/0x74
       [<ffffffff81050446>] ? __local_bh_enable_ip+0x9b/0xa1
       [<ffffffff8108f9ca>] ? trace_hardirqs_on_caller+0x16d/0x189
       [<ffffffff810915f4>] lock_acquire+0x122/0x1b6
       [<ffffffff810915f4>] ? lock_acquire+0x122/0x1b6
       [<ffffffff814c928f>] ? skb_dequeue+0x18/0x61
       [<ffffffff81609dbf>] _raw_spin_lock_irqsave+0x35/0x49
       [<ffffffff814c928f>] ? skb_dequeue+0x18/0x61
       [<ffffffff814c928f>] skb_dequeue+0x18/0x61
       [<ffffffffa009aa92>] afs_deliver_to_call+0x344/0x39d [kafs]
       [<ffffffffa009ab37>] afs_process_async_call+0x4c/0xd5 [kafs]
       [<ffffffffa0099e9c>] afs_async_workfn+0xe/0x10 [kafs]
       [<ffffffff81063a3a>] process_one_work+0x29d/0x57c
       [<ffffffff81064ac2>] worker_thread+0x24a/0x385
       [<ffffffff81064878>] ? rescuer_thread+0x2d0/0x2d0
       [<ffffffff810696f5>] kthread+0xf3/0xfb
       [<ffffffff8160a6ff>] ret_from_fork+0x1f/0x40
       [<ffffffff81069602>] ? kthread_create_on_node+0x1cf/0x1cf
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      372ee163
  2. 11 Apr, 2016 2 commits
  3. 31 Jul, 2013 1 commit
  4. 24 Apr, 2011 1 commit
  5. 26 Apr, 2007 2 commits
    • David Howells's avatar
      [AF_RXRPC]: Add an interface to the AF_RXRPC module for the AFS filesystem to use · 651350d1
      David Howells authored
      Add an interface to the AF_RXRPC module so that the AFS filesystem module can
      more easily make use of the services available.  AFS still opens a socket but
      then uses the action functions in lieu of sendmsg() and registers an intercept
      functions to grab messages before they're queued on the socket Rx queue.
      
      This permits AFS (or whatever) to:
      
       (1) Avoid the overhead of using the recvmsg() call.
      
       (2) Use different keys directly on individual client calls on one socket
           rather than having to open a whole slew of sockets, one for each key it
           might want to use.
      
       (3) Avoid calling request_key() at the point of issue of a call or opening of
           a socket.  This is done instead by AFS at the point of open(), unlink() or
           other VFS operation and the key handed through.
      
       (4) Request the use of something other than GFP_KERNEL to allocate memory.
      
      Furthermore:
      
       (*) The socket buffer markings used by RxRPC are made available for AFS so
           that it can interpret the cooked RxRPC messages itself.
      
       (*) rxgen (un)marshalling abort codes are made available.
      
      
      The following documentation for the kernel interface is added to
      Documentation/networking/rxrpc.txt:
      
      =========================
      AF_RXRPC KERNEL INTERFACE
      =========================
      
      The AF_RXRPC module also provides an interface for use by in-kernel utilities
      such as the AFS filesystem.  This permits such a utility to:
      
       (1) Use different keys directly on individual client calls on one socket
           rather than having to open a whole slew of sockets, one for each key it
           might want to use.
      
       (2) Avoid having RxRPC call request_key() at the point of issue of a call or
           opening of a socket.  Instead the utility is responsible for requesting a
           key at the appropriate point.  AFS, for instance, would do this during VFS
           operations such as open() or unlink().  The key is then handed through
           when the call is initiated.
      
       (3) Request the use of something other than GFP_KERNEL to allocate memory.
      
       (4) Avoid the overhead of using the recvmsg() call.  RxRPC messages can be
           intercepted before they get put into the socket Rx queue and the socket
           buffers manipulated directly.
      
      To use the RxRPC facility, a kernel utility must still open an AF_RXRPC socket,
      bind an addess as appropriate and listen if it's to be a server socket, but
      then it passes this to the kernel interface functions.
      
      The kernel interface functions are as follows:
      
       (*) Begin a new client call.
      
      	struct rxrpc_call *
      	rxrpc_kernel_begin_call(struct socket *sock,
      				struct sockaddr_rxrpc *srx,
      				struct key *key,
      				unsigned long user_call_ID,
      				gfp_t gfp);
      
           This allocates the infrastructure to make a new RxRPC call and assigns
           call and connection numbers.  The call will be made on the UDP port that
           the socket is bound to.  The call will go to the destination address of a
           connected client socket unless an alternative is supplied (srx is
           non-NULL).
      
           If a key is supplied then this will be used to secure the call instead of
           the key bound to the socket with the RXRPC_SECURITY_KEY sockopt.  Calls
           secured in this way will still share connections if at all possible.
      
           The user_call_ID is equivalent to that supplied to sendmsg() in the
           control data buffer.  It is entirely feasible to use this to point to a
           kernel data structure.
      
           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.
      
       (*) End a client call.
      
      	void rxrpc_kernel_end_call(struct rxrpc_call *call);
      
           This is used to end a previously begun call.  The user_call_ID is expunged
           from AF_RXRPC's knowledge and will not be seen again in association with
           the specified call.
      
       (*) Send data through a call.
      
      	int rxrpc_kernel_send_data(struct rxrpc_call *call, struct msghdr *msg,
      				   size_t len);
      
           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
           data buffers to be used.  msg_iov may not be NULL and must point
           exclusively to in-kernel virtual addresses.  msg.msg_flags may be given
           MSG_MORE if there will be subsequent data sends for this call.
      
           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.
      
       (*) Abort a call.
      
      	void rxrpc_kernel_abort_call(struct rxrpc_call *call, u32 abort_code);
      
           This is used to abort a call if it's still in an abortable state.  The
           abort code specified will be placed in the ABORT message sent.
      
       (*) Intercept received RxRPC messages.
      
      	typedef void (*rxrpc_interceptor_t)(struct sock *sk,
      					    unsigned long user_call_ID,
      					    struct sk_buff *skb);
      
      	void
      	rxrpc_kernel_intercept_rx_messages(struct socket *sock,
      					   rxrpc_interceptor_t interceptor);
      
           This installs an interceptor function on the specified AF_RXRPC socket.
           All messages that would otherwise wind up in the socket's Rx queue are
           then diverted to this function.  Note that care must be taken to process
           the messages in the right order to maintain DATA message sequentiality.
      
           The interceptor function itself is provided with the address of the socket
           and handling the incoming message, the ID assigned by the kernel utility
           to the call and the socket buffer containing the message.
      
           The skb->mark field indicates the type of message:
      
      	MARK				MEANING
      	===============================	=======================================
      	RXRPC_SKB_MARK_DATA		Data message
      	RXRPC_SKB_MARK_FINAL_ACK	Final ACK received for an incoming call
      	RXRPC_SKB_MARK_BUSY		Client call rejected as server busy
      	RXRPC_SKB_MARK_REMOTE_ABORT	Call aborted by peer
      	RXRPC_SKB_MARK_NET_ERROR	Network error detected
      	RXRPC_SKB_MARK_LOCAL_ERROR	Local error encountered
      	RXRPC_SKB_MARK_NEW_CALL		New incoming call awaiting acceptance
      
           The remote abort message can be probed with rxrpc_kernel_get_abort_code().
           The two error messages can be probed with rxrpc_kernel_get_error_number().
           A new call can be accepted with rxrpc_kernel_accept_call().
      
           Data messages can have their contents extracted with the usual bunch of
           socket buffer manipulation functions.  A data message can be determined to
           be the last one in a sequence with rxrpc_kernel_is_data_last().  When a
           data message has been used up, rxrpc_kernel_data_delivered() should be
           called on it..
      
           Non-data messages should be handled to rxrpc_kernel_free_skb() to dispose
           of.  It is possible to get extra refs on all types of message for later
           freeing, but this may pin the state of a call until the message is finally
           freed.
      
       (*) Accept an incoming call.
      
      	struct rxrpc_call *
      	rxrpc_kernel_accept_call(struct socket *sock,
      				 unsigned long user_call_ID);
      
           This is used to accept an incoming call and to assign it a call ID.  This
           function is similar to rxrpc_kernel_begin_call() and calls accepted must
           be ended in the same way.
      
           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.
      
       (*) Reject an incoming call.
      
      	int rxrpc_kernel_reject_call(struct socket *sock);
      
           This is used to reject the first incoming call on the socket's queue with
           a BUSY message.  -ENODATA is returned if there were no incoming calls.
           Other errors may be returned if the call had been aborted (-ECONNABORTED)
           or had timed out (-ETIME).
      
       (*) Record the delivery of a data message and free it.
      
      	void rxrpc_kernel_data_delivered(struct sk_buff *skb);
      
           This is used to record a data message as having been delivered and to
           update the ACK state for the call.  The socket buffer will be freed.
      
       (*) Free a message.
      
      	void rxrpc_kernel_free_skb(struct sk_buff *skb);
      
           This is used to free a non-DATA socket buffer intercepted from an AF_RXRPC
           socket.
      
       (*) Determine if a data message is the last one on a call.
      
      	bool rxrpc_kernel_is_data_last(struct sk_buff *skb);
      
           This is used to determine if a socket buffer holds the last data message
           to be received for a call (true will be returned if it does, false
           if not).
      
           The data message will be part of the reply on a client call and the
           request on an incoming call.  In the latter case there will be more
           messages, but in the former case there will not.
      
       (*) Get the abort code from an abort message.
      
      	u32 rxrpc_kernel_get_abort_code(struct sk_buff *skb);
      
           This is used to extract the abort code from a remote abort message.
      
       (*) Get the error number from a local or network error message.
      
      	int rxrpc_kernel_get_error_number(struct sk_buff *skb);
      
           This is used to extract the error number from a message indicating either
           a local error occurred or a network error occurred.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      651350d1
    • David Howells's avatar
      [AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both · 17926a79
      David Howells authored
      Provide AF_RXRPC sockets that can be used to talk to AFS servers, or serve
      answers to AFS clients.  KerberosIV security is fully supported.  The patches
      and some example test programs can be found in:
      
      	http://people.redhat.com/~dhowells/rxrpc/
      
      This will eventually replace the old implementation of kernel-only RxRPC
      currently resident in net/rxrpc/.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      17926a79
  6. 08 Jan, 2006 1 commit
    • David Howells's avatar
      [PATCH] frv: miscellaneous changes · 41be6aef
      David Howells authored
      Fix a number of miscellanous items:
      
       (1) Declare lock sections in the linker script.
      
       (2) Recurse in the correct manner in the arch makefile.
      
       (3) asm/bug.h requires asm/linkage.h to be included first. One C file puts
           asm/bug.h first.
      
       (4) Add an empty RTC header file to avoid missing header file errors.
      
       (5) sg_dma_address() should use the dma_address member of a scatter list.
      
       (6) Add trivial pci_unmap support.
      
       (7) Add pgprot_noncached()
      
       (8) Discard u_quad_t.
      
       (9) Use ~0UL rather than ULONG_MAX in unistd.h in case the latter isn't
           declared.
      
      (10) Add an empty VGA header file to avoid missing header file errors.
      
      (11) Add an XOR header file to use the generic XOR stuff.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      41be6aef
  7. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4