fs/cifs/smb1ops.c

   1 /*
   2  *  SMB1 (CIFS) version specific operations
   3  *
   4  *  Copyright (c) 2012, Jeff Layton <jlayton@redhat.com>
   5  *
   6  *  This library is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License v2 as published
   8  *  by the Free Software Foundation.
   9  *
  10  *  This library is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  13  *  the GNU Lesser General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU Lesser General Public License
  16  *  along with this library; if not, write to the Free Software
  17  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  18  */
  19
  20 #include "cifsglob.h"
  21 #include "cifsproto.h"
  22 #include "cifs_debug.h"
  23 #include "cifspdu.h"
  24
  25 /*
  26  * An NT cancel request header looks just like the original request except:
  27  *
  28  * The Command is SMB_COM_NT_CANCEL
  29  * The WordCount is zeroed out
  30  * The ByteCount is zeroed out
  31  *
  32  * This function mangles an existing request buffer into a
  33  * SMB_COM_NT_CANCEL request and then sends it.
  34  */
  35 static int
  36 send_nt_cancel(struct TCP_Server_Info *server, void *buf,
  37                struct mid_q_entry *mid)
  38 {
  39         int rc = 0;
  40         struct smb_hdr *in_buf = (struct smb_hdr *)buf;
  41
  42         /* -4 for RFC1001 length and +2 for BCC field */
  43         in_buf->smb_buf_length = cpu_to_be32(sizeof(struct smb_hdr) - 4  + 2);
  44         in_buf->Command = SMB_COM_NT_CANCEL;
  45         in_buf->WordCount = 0;
  46         put_bcc(0, in_buf);
  47
  48         mutex_lock(&server->srv_mutex);
  49         rc = cifs_sign_smb(in_buf, server, &mid->sequence_number);
  50         if (rc) {
  51                 mutex_unlock(&server->srv_mutex);
  52                 return rc;
  53         }
  54         rc = smb_send(server, in_buf, be32_to_cpu(in_buf->smb_buf_length));
  55         mutex_unlock(&server->srv_mutex);
  56
  57         cFYI(1, "issued NT_CANCEL for mid %u, rc = %d",
  58                 in_buf->Mid, rc);
  59
  60         return rc;
  61 }
  62
  63 static bool
  64 cifs_compare_fids(struct cifsFileInfo *ob1, struct cifsFileInfo *ob2)
  65 {
  66         return ob1->netfid == ob2->netfid;
  67 }
  68
  69 static unsigned int
  70 cifs_read_data_offset(char *buf)
  71 {
  72         READ_RSP *rsp = (READ_RSP *)buf;
  73         return le16_to_cpu(rsp->DataOffset);
  74 }
  75
  76 static unsigned int
  77 cifs_read_data_length(char *buf)
  78 {
  79         READ_RSP *rsp = (READ_RSP *)buf;
  80         return (le16_to_cpu(rsp->DataLengthHigh) << 16) +
  81                le16_to_cpu(rsp->DataLength);
  82 }
  83
  84 static struct mid_q_entry *
  85 cifs_find_mid(struct TCP_Server_Info *server, char *buffer)
  86 {
  87         struct smb_hdr *buf = (struct smb_hdr *)buffer;
  88         struct mid_q_entry *mid;
  89
  90         spin_lock(&GlobalMid_Lock);
  91         list_for_each_entry(mid, &server->pending_mid_q, qhead) {
  92                 if (mid->mid == buf->Mid &&
  93                     mid->mid_state == MID_REQUEST_SUBMITTED &&
  94                     le16_to_cpu(mid->command) == buf->Command) {
  95                         spin_unlock(&GlobalMid_Lock);
  96                         return mid;
  97                 }
  98         }
  99         spin_unlock(&GlobalMid_Lock);
 100         return NULL;
 101 }
 102
 103 static void
 104 cifs_add_credits(struct TCP_Server_Info *server, const unsigned int add)
 105 {
 106         spin_lock(&server->req_lock);
 107         server->credits += add;
 108         server->in_flight--;
 109         spin_unlock(&server->req_lock);
 110         wake_up(&server->request_q);
 111 }
 112
 113 static void
 114 cifs_set_credits(struct TCP_Server_Info *server, const int val)
 115 {
 116         spin_lock(&server->req_lock);
 117         server->credits = val;
 118         server->oplocks = val > 1 ? enable_oplocks : false;
 119         spin_unlock(&server->req_lock);
 120 }
 121
 122 static int *
 123 cifs_get_credits_field(struct TCP_Server_Info *server)
 124 {
 125         return &server->credits;
 126 }
 127
 128 /*
 129  * Find a free multiplex id (SMB mid). Otherwise there could be
 130  * mid collisions which might cause problems, demultiplexing the
 131  * wrong response to this request. Multiplex ids could collide if
 132  * one of a series requests takes much longer than the others, or
 133  * if a very large number of long lived requests (byte range
 134  * locks or FindNotify requests) are pending. No more than
 135  * 64K-1 requests can be outstanding at one time. If no
 136  * mids are available, return zero. A future optimization
 137  * could make the combination of mids and uid the key we use
 138  * to demultiplex on (rather than mid alone).
 139  * In addition to the above check, the cifs demultiplex
 140  * code already used the command code as a secondary
 141  * check of the frame and if signing is negotiated the
 142  * response would be discarded if the mid were the same
 143  * but the signature was wrong. Since the mid is not put in the
 144  * pending queue until later (when it is about to be dispatched)
 145  * we do have to limit the number of outstanding requests
 146  * to somewhat less than 64K-1 although it is hard to imagine
 147  * so many threads being in the vfs at one time.
 148  */
 149 static __u64
 150 cifs_get_next_mid(struct TCP_Server_Info *server)
 151 {
 152         __u64 mid = 0;
 153         __u16 last_mid, cur_mid;
 154         bool collision;
 155
 156         spin_lock(&GlobalMid_Lock);
 157
 158         /* mid is 16 bit only for CIFS/SMB */
 159         cur_mid = (__u16)((server->CurrentMid) & 0xffff);
 160         /* we do not want to loop forever */
 161         last_mid = cur_mid;
 162         cur_mid++;
 163
 164         /*
 165          * This nested loop looks more expensive than it is.
 166          * In practice the list of pending requests is short,
 167          * fewer than 50, and the mids are likely to be unique
 168          * on the first pass through the loop unless some request
 169          * takes longer than the 64 thousand requests before it
 170          * (and it would also have to have been a request that
 171          * did not time out).
 172          */
 173         while (cur_mid != last_mid) {
 174                 struct mid_q_entry *mid_entry;
 175                 unsigned int num_mids;
 176
 177                 collision = false;
 178                 if (cur_mid == 0)
 179                         cur_mid++;
 180
 181                 num_mids = 0;
 182                 list_for_each_entry(mid_entry, &server->pending_mid_q, qhead) {
 183                         ++num_mids;
 184                         if (mid_entry->mid == cur_mid &&
 185                             mid_entry->mid_state == MID_REQUEST_SUBMITTED) {
 186                                 /* This mid is in use, try a different one */
 187                                 collision = true;
 188                                 break;
 189                         }
 190                 }
 191
 192                 /*
 193                  * if we have more than 32k mids in the list, then something
 194                  * is very wrong. Possibly a local user is trying to DoS the
 195                  * box by issuing long-running calls and SIGKILL'ing them. If
 196                  * we get to 2^16 mids then we're in big trouble as this
 197                  * function could loop forever.
 198                  *
 199                  * Go ahead and assign out the mid in this situation, but force
 200                  * an eventual reconnect to clean out the pending_mid_q.
 201                  */
 202                 if (num_mids > 32768)
 203                         server->tcpStatus = CifsNeedReconnect;
 204
 205                 if (!collision) {
 206                         mid = (__u64)cur_mid;
 207                         server->CurrentMid = mid;
 208                         break;
 209                 }
 210                 cur_mid++;
 211         }
 212         spin_unlock(&GlobalMid_Lock);
 213         return mid;
 214 }
 215
 216 struct smb_version_operations smb1_operations = {
 217         .send_cancel = send_nt_cancel,
 218         .compare_fids = cifs_compare_fids,
 219         .setup_request = cifs_setup_request,
 220         .check_receive = cifs_check_receive,
 221         .add_credits = cifs_add_credits,
 222         .set_credits = cifs_set_credits,
 223         .get_credits_field = cifs_get_credits_field,
 224         .get_next_mid = cifs_get_next_mid,
 225         .read_data_offset = cifs_read_data_offset,
 226         .read_data_length = cifs_read_data_length,
 227         .map_error = map_smb_to_linux_error,
 228         .find_mid = cifs_find_mid,
 229         .check_message = checkSMB,
 230         .dump_detail = cifs_dump_detail,
 231         .is_oplock_break = is_valid_oplock_break,
 232 };
 233
 234 struct smb_version_values smb1_values = {
 235         .version_string = SMB1_VERSION_STRING,
 236         .large_lock_type = LOCKING_ANDX_LARGE_FILES,
 237         .exclusive_lock_type = 0,
 238         .shared_lock_type = LOCKING_ANDX_SHARED_LOCK,
 239         .unlock_lock_type = 0,
 240         .header_size = sizeof(struct smb_hdr),
 241         .max_header_size = MAX_CIFS_HDR_SIZE,
 242         .read_rsp_size = sizeof(READ_RSP),
 243 };