cvs commit: src/sys/kern uipc_socket.c uipc_usrreq.c src/sys/netatm atm_cm.c atm_socket.c atm_var.h src/sys/netgraph/bluetooth/socket ng_btsocket_l2cap.c ng_btsocket_rfcomm.c src/sys/netinet ...

[Robert Watson]

rwatson     2005-02-21 21:58:17 UTC

  FreeBSD src repository

  Modified files:
    sys/kern             uipc_socket.c uipc_usrreq.c 
    sys/netatm           atm_cm.c atm_socket.c atm_var.h 
    sys/netatm/ipatm     ipatm_load.c 
    sys/netgraph/bluetooth/socket ng_btsocket_l2cap.c 
                                  ng_btsocket_rfcomm.c 
    sys/netinet          tcp_usrreq.c 
    sys/netipx           spx_usrreq.c 
    sys/sys              socketvar.h 
  Log:
  In the current world order, solisten() implements the state transition of
  a socket from a regular socket to a listening socket able to accept new
  connections.  As part of this state transition, solisten() calls into the
  protocol to update protocol-layer state.  There were several bugs in this
  implementation that could result in a race wherein a TCP SYN received
  in the interval between the protocol state transition and the shortly
  following socket layer transition would result in a panic in the TCP code,
  as the socket would be in the TCPS_LISTEN state, but the socket would not
  have the SO_ACCEPTCONN flag set.
  
  This change does the following:
  
  - Pushes the socket state transition from the socket layer solisten() to
    to socket "library" routines called from the protocol.  This permits
    the socket routines to be called while holding the protocol mutexes,
    preventing a race exposing the incomplete socket state transition to TCP
    after the TCP state transition has completed.  The check for a socket
    layer state transition is performed by solisten_proto_check(), and the
    actual transition is performed by solisten_proto().
  
  - Holds the socket lock for the duration of the socket state test and set,
    and over the protocol layer state transition, which is now possible as
    the socket lock is acquired by the protocol layer, rather than vice
    versa.  This prevents additional state related races in the socket
    layer.
  
  This permits the dual transition of socket layer and protocol layer state
  to occur while holding locks for both layers, making the two changes
  atomic with respect to one another.  Similar changes are likely require
  elsewhere in the socket/protocol code.
  
  Reported by:            Peter Holm <peter at holm.cc>
  Review and fixes from:  emax, Antoine Brodin <antoine.brodin at laposte.net>
  Philosophical head nod: gnn
  
  Revision  Changes    Path
  1.233     +42 -14    src/sys/kern/uipc_socket.c
  1.151     +14 -9     src/sys/kern/uipc_usrreq.c
  1.33      +13 -1     src/sys/netatm/atm_cm.c
  1.23      +1 -1      src/sys/netatm/atm_socket.c
  1.26      +2 -2      src/sys/netatm/atm_var.h
  1.21      +2 -2      src/sys/netatm/ipatm/ipatm_load.c
  1.16      +21 -6     src/sys/netgraph/bluetooth/socket/ng_btsocket_l2cap.c
  1.15      +25 -19    src/sys/netgraph/bluetooth/socket/ng_btsocket_rfcomm.c
  1.115     +14 -4     src/sys/netinet/tcp_usrreq.c
  1.62      +7 -2      src/sys/netipx/spx_usrreq.c
  1.139     +2 -0      src/sys/sys/socketvar.h