fs/dlm/midcomms.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /******************************************************************************
   3 *******************************************************************************
   4 **
   5 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   6 **  Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   7 **
   8 **
   9 *******************************************************************************
  10 ******************************************************************************/
  11
  12 /*
  13  * midcomms.c
  14  *
  15  * This is the appallingly named "mid-level" comms layer.
  16  *
  17  * Its purpose is to take packets from the "real" comms layer,
  18  * split them up into packets and pass them to the interested
  19  * part of the locking mechanism.
  20  *
  21  * It also takes messages from the locking layer, formats them
  22  * into packets and sends them to the comms layer.
  23  */
  24
  25 #include "dlm_internal.h"
  26 #include "lowcomms.h"
  27 #include "config.h"
  28 #include "lock.h"
  29 #include "midcomms.h"
  30
  31 struct dlm_mhandle *dlm_midcomms_get_mhandle(int nodeid, int len,
  32                                              gfp_t allocation, char **ppc)
  33 {
  34         return dlm_lowcomms_get_buffer(nodeid, len, allocation, ppc);
  35 }
  36
  37 void dlm_midcomms_commit_mhandle(struct dlm_mhandle *mh)
  38 {
  39         dlm_lowcomms_commit_buffer(mh);
  40 }
  41
  42 void dlm_midcomms_add_member(int nodeid) { }
  43
  44 void dlm_midcomms_remove_member(int nodeid) { }
  45
  46 int dlm_midcomms_start(void)
  47 {
  48         return dlm_lowcomms_start();
  49 }
  50
  51 void dlm_midcomms_shutdown(void)
  52 {
  53         dlm_lowcomms_shutdown();
  54 }
  55
  56 int dlm_midcomms_close(int nodeid)
  57 {
  58         return dlm_lowcomms_close(nodeid);
  59 }
  60
  61 /*
  62  * Called from the low-level comms layer to process a buffer of
  63  * commands.
  64  */
  65
  66 int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
  67 {
  68         const unsigned char *ptr = buf;
  69         const struct dlm_header *hd;
  70         uint16_t msglen;
  71         int ret = 0;
  72
  73         while (len >= sizeof(struct dlm_header)) {
  74                 hd = (struct dlm_header *)ptr;
  75
  76                 /* no message should be more than DEFAULT_BUFFER_SIZE or
  77                  * less than dlm_header size.
  78                  *
  79                  * Some messages does not have a 8 byte length boundary yet
  80                  * which can occur in a unaligned memory access of some dlm
  81                  * messages. However this problem need to be fixed at the
  82                  * sending side, for now it seems nobody run into architecture
  83                  * related issues yet but it slows down some processing.
  84                  * Fixing this issue should be scheduled in future by doing
  85                  * the next major version bump.
  86                  */
  87                 msglen = le16_to_cpu(hd->h_length);
  88                 if (msglen > DEFAULT_BUFFER_SIZE ||
  89                     msglen < sizeof(struct dlm_header)) {
  90                         log_print("received invalid length header: %u from node %d, will abort message parsing",
  91                                   msglen, nodeid);
  92                         return -EBADMSG;
  93                 }
  94
  95                 /* caller will take care that leftover
  96                  * will be parsed next call with more data
  97                  */
  98                 if (msglen > len)
  99                         break;
 100
 101                 switch (hd->h_cmd) {
 102                 case DLM_MSG:
 103                         if (msglen < sizeof(struct dlm_message)) {
 104                                 log_print("dlm msg too small: %u, will skip this message",
 105                                           msglen);
 106                                 goto skip;
 107                         }
 108
 109                         break;
 110                 case DLM_RCOM:
 111                         if (msglen < sizeof(struct dlm_rcom)) {
 112                                 log_print("dlm rcom msg too small: %u, will skip this message",
 113                                           msglen);
 114                                 goto skip;
 115                         }
 116
 117                         break;
 118                 default:
 119                         log_print("unsupported h_cmd received: %u, will skip this message",
 120                                   hd->h_cmd);
 121                         goto skip;
 122                 }
 123
 124                 dlm_receive_buffer((union dlm_packet *)ptr, nodeid);
 125
 126 skip:
 127                 ret += msglen;
 128                 len -= msglen;
 129                 ptr += msglen;
 130         }
 131
 132         return ret;
 133 }