fs/cifs/smb1ops.c

/*
 *  SMB1 (CIFS) version specific operations
 *
 *  Copyright (c) 2012, Jeff Layton <jlayton@redhat.com>
 *
 *  This library is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License v2 as published
 *  by the Free Software Foundation.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *  the GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifspdu.h"

/*
 * An NT cancel request header looks just like the original request except:
 *
 * The Command is SMB_COM_NT_CANCEL
 * The WordCount is zeroed out
 * The ByteCount is zeroed out
 *
 * This function mangles an existing request buffer into a
 * SMB_COM_NT_CANCEL request and then sends it.
 */
static int
send_nt_cancel(struct TCP_Server_Info *server, void *buf,
	       struct mid_q_entry *mid)
{
	int rc = 0;
	struct smb_hdr *in_buf = (struct smb_hdr *)buf;

	/* -4 for RFC1001 length and +2 for BCC field */
	in_buf->smb_buf_length = cpu_to_be32(sizeof(struct smb_hdr) - 4  + 2);
	in_buf->Command = SMB_COM_NT_CANCEL;
	in_buf->WordCount = 0;
	put_bcc(0, in_buf);

	mutex_lock(&server->srv_mutex);
	rc = cifs_sign_smb(in_buf, server, &mid->sequence_number);
	if (rc) {
		mutex_unlock(&server->srv_mutex);
		return rc;
	}
	rc = smb_send(server, in_buf, be32_to_cpu(in_buf->smb_buf_length));
	mutex_unlock(&server->srv_mutex);

	cFYI(1, "issued NT_CANCEL for mid %u, rc = %d",
		in_buf->Mid, rc);

	return rc;
}

static bool
cifs_compare_fids(struct cifsFileInfo *ob1, struct cifsFileInfo *ob2)
{
	return ob1->netfid == ob2->netfid;
}

static unsigned int
cifs_read_data_offset(char *buf)
{
	READ_RSP *rsp = (READ_RSP *)buf;
	return le16_to_cpu(rsp->DataOffset);
}

static unsigned int
cifs_read_data_length(char *buf)
{
	READ_RSP *rsp = (READ_RSP *)buf;
	return (le16_to_cpu(rsp->DataLengthHigh) << 16) +
	       le16_to_cpu(rsp->DataLength);
}

static struct mid_q_entry *
cifs_find_mid(struct TCP_Server_Info *server, char *buffer)
{
	struct smb_hdr *buf = (struct smb_hdr *)buffer;
	struct mid_q_entry *mid;

	spin_lock(&GlobalMid_Lock);
	list_for_each_entry(mid, &server->pending_mid_q, qhead) {
		if (mid->mid == buf->Mid &&
		    mid->mid_state == MID_REQUEST_SUBMITTED &&
		    le16_to_cpu(mid->command) == buf->Command) {
			spin_unlock(&GlobalMid_Lock);
			return mid;
		}
	}
	spin_unlock(&GlobalMid_Lock);
	return NULL;
}

static void
cifs_add_credits(struct TCP_Server_Info *server, const unsigned int add)
{
	spin_lock(&server->req_lock);
	server->credits += add;
	server->in_flight--;
	spin_unlock(&server->req_lock);
	wake_up(&server->request_q);
}

static void
cifs_set_credits(struct TCP_Server_Info *server, const int val)
{
	spin_lock(&server->req_lock);
	server->credits = val;
	server->oplocks = val > 1 ? enable_oplocks : false;
	spin_unlock(&server->req_lock);
}

static int *
cifs_get_credits_field(struct TCP_Server_Info *server)
{
	return &server->credits;
}

/*
 * Find a free multiplex id (SMB mid). Otherwise there could be
 * mid collisions which might cause problems, demultiplexing the
 * wrong response to this request. Multiplex ids could collide if
 * one of a series requests takes much longer than the others, or
 * if a very large number of long lived requests (byte range
 * locks or FindNotify requests) are pending. No more than
 * 64K-1 requests can be outstanding at one time. If no
 * mids are available, return zero. A future optimization
 * could make the combination of mids and uid the key we use
 * to demultiplex on (rather than mid alone).
 * In addition to the above check, the cifs demultiplex
 * code already used the command code as a secondary
 * check of the frame and if signing is negotiated the
 * response would be discarded if the mid were the same
 * but the signature was wrong. Since the mid is not put in the
 * pending queue until later (when it is about to be dispatched)
 * we do have to limit the number of outstanding requests
 * to somewhat less than 64K-1 although it is hard to imagine
 * so many threads being in the vfs at one time.
 */
static __u64
cifs_get_next_mid(struct TCP_Server_Info *server)
{
	__u64 mid = 0;
	__u16 last_mid, cur_mid;
	bool collision;

	spin_lock(&GlobalMid_Lock);

	/* mid is 16 bit only for CIFS/SMB */
	cur_mid = (__u16)((server->CurrentMid) & 0xffff);
	/* we do not want to loop forever */
	last_mid = cur_mid;
	cur_mid++;

	/*
	 * This nested loop looks more expensive than it is.
	 * In practice the list of pending requests is short,
	 * fewer than 50, and the mids are likely to be unique
	 * on the first pass through the loop unless some request
	 * takes longer than the 64 thousand requests before it
	 * (and it would also have to have been a request that
	 * did not time out).
	 */
	while (cur_mid != last_mid) {
		struct mid_q_entry *mid_entry;
		unsigned int num_mids;

		collision = false;
		if (cur_mid == 0)
			cur_mid++;

		num_mids = 0;
		list_for_each_entry(mid_entry, &server->pending_mid_q, qhead) {
			++num_mids;
			if (mid_entry->mid == cur_mid &&
			    mid_entry->mid_state == MID_REQUEST_SUBMITTED) {
				/* This mid is in use, try a different one */
				collision = true;
				break;
			}
		}

		/*
		 * if we have more than 32k mids in the list, then something
		 * is very wrong. Possibly a local user is trying to DoS the
		 * box by issuing long-running calls and SIGKILL'ing them. If
		 * we get to 2^16 mids then we're in big trouble as this
		 * function could loop forever.
		 *
		 * Go ahead and assign out the mid in this situation, but force
		 * an eventual reconnect to clean out the pending_mid_q.
		 */
		if (num_mids > 32768)
			server->tcpStatus = CifsNeedReconnect;

		if (!collision) {
			mid = (__u64)cur_mid;
			server->CurrentMid = mid;
			break;
		}
		cur_mid++;
	}
	spin_unlock(&GlobalMid_Lock);
	return mid;
}

/*
	return codes:
		0	not a transact2, or all data present
		>0	transact2 with that much data missing
		-EINVAL	invalid transact2
 */
static int
check2ndT2(char *buf)
{
	struct smb_hdr *pSMB = (struct smb_hdr *)buf;
	struct smb_t2_rsp *pSMBt;
	int remaining;
	__u16 total_data_size, data_in_this_rsp;

	if (pSMB->Command != SMB_COM_TRANSACTION2)
		return 0;

	/* check for plausible wct, bcc and t2 data and parm sizes */
	/* check for parm and data offset going beyond end of smb */
	if (pSMB->WordCount != 10) { /* coalesce_t2 depends on this */
		cFYI(1, "invalid transact2 word count");
		return -EINVAL;
	}

	pSMBt = (struct smb_t2_rsp *)pSMB;

	total_data_size = get_unaligned_le16(&pSMBt->t2_rsp.TotalDataCount);
	data_in_this_rsp = get_unaligned_le16(&pSMBt->t2_rsp.DataCount);

	if (total_data_size == data_in_this_rsp)
		return 0;
	else if (total_data_size < data_in_this_rsp) {
		cFYI(1, "total data %d smaller than data in frame %d",
			total_data_size, data_in_this_rsp);
		return -EINVAL;
	}

	remaining = total_data_size - data_in_this_rsp;

	cFYI(1, "missing %d bytes from transact2, check next response",
		remaining);
	if (total_data_size > CIFSMaxBufSize) {
		cERROR(1, "TotalDataSize %d is over maximum buffer %d",
			total_data_size, CIFSMaxBufSize);
		return -EINVAL;
	}
	return remaining;
}

static int
coalesce_t2(char *second_buf, struct smb_hdr *target_hdr)
{
	struct smb_t2_rsp *pSMBs = (struct smb_t2_rsp *)second_buf;
	struct smb_t2_rsp *pSMBt  = (struct smb_t2_rsp *)target_hdr;
	char *data_area_of_tgt;
	char *data_area_of_src;
	int remaining;
	unsigned int byte_count, total_in_tgt;
	__u16 tgt_total_cnt, src_total_cnt, total_in_src;

	src_total_cnt = get_unaligned_le16(&pSMBs->t2_rsp.TotalDataCount);
	tgt_total_cnt = get_unaligned_le16(&pSMBt->t2_rsp.TotalDataCount);

	if (tgt_total_cnt != src_total_cnt)
		cFYI(1, "total data count of primary and secondary t2 differ "
			"source=%hu target=%hu", src_total_cnt, tgt_total_cnt);

	total_in_tgt = get_unaligned_le16(&pSMBt->t2_rsp.DataCount);

	remaining = tgt_total_cnt - total_in_tgt;

	if (remaining < 0) {
		cFYI(1, "Server sent too much data. tgt_total_cnt=%hu "
			"total_in_tgt=%hu", tgt_total_cnt, total_in_tgt);
		return -EPROTO;
	}

	if (remaining == 0) {
		/* nothing to do, ignore */
		cFYI(1, "no more data remains");
		return 0;
	}

	total_in_src = get_unaligned_le16(&pSMBs->t2_rsp.DataCount);
	if (remaining < total_in_src)
		cFYI(1, "transact2 2nd response contains too much data");

	/* find end of first SMB data area */
	data_area_of_tgt = (char *)&pSMBt->hdr.Protocol +
				get_unaligned_le16(&pSMBt->t2_rsp.DataOffset);

	/* validate target area */
	data_area_of_src = (char *)&pSMBs->hdr.Protocol +
				get_unaligned_le16(&pSMBs->t2_rsp.DataOffset);

	data_area_of_tgt += total_in_tgt;

	total_in_tgt += total_in_src;
	/* is the result too big for the field? */
	if (total_in_tgt > USHRT_MAX) {
		cFYI(1, "coalesced DataCount too large (%u)", total_in_tgt);
		return -EPROTO;
	}
	put_unaligned_le16(total_in_tgt, &pSMBt->t2_rsp.DataCount);

	/* fix up the BCC */
	byte_count = get_bcc(target_hdr);
	byte_count += total_in_src;
	/* is the result too big for the field? */
	if (byte_count > USHRT_MAX) {
		cFYI(1, "coalesced BCC too large (%u)", byte_count);
		return -EPROTO;
	}
	put_bcc(byte_count, target_hdr);

	byte_count = be32_to_cpu(target_hdr->smb_buf_length);
	byte_count += total_in_src;
	/* don't allow buffer to overflow */
	if (byte_count > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
		cFYI(1, "coalesced BCC exceeds buffer size (%u)", byte_count);
		return -ENOBUFS;
	}
	target_hdr->smb_buf_length = cpu_to_be32(byte_count);

	/* copy second buffer into end of first buffer */
	memcpy(data_area_of_tgt, data_area_of_src, total_in_src);

	if (remaining != total_in_src) {
		/* more responses to go */
		cFYI(1, "waiting for more secondary responses");
		return 1;
	}

	/* we are done */
	cFYI(1, "found the last secondary response");
	return 0;
}

static bool
cifs_check_trans2(struct mid_q_entry *mid, struct TCP_Server_Info *server,
		  char *buf, int malformed)
{
	if (malformed)
		return false;
	if (check2ndT2(buf) <= 0)
		return false;
	mid->multiRsp = true;
	if (mid->resp_buf) {
		/* merge response - fix up 1st*/
		malformed = coalesce_t2(buf, mid->resp_buf);
		if (malformed > 0)
			return true;
		/* All parts received or packet is malformed. */
		mid->multiEnd = true;
		dequeue_mid(mid, malformed);
		return true;
	}
	if (!server->large_buf) {
		/*FIXME: switch to already allocated largebuf?*/
		cERROR(1, "1st trans2 resp needs bigbuf");
	} else {
		/* Have first buffer */
		mid->resp_buf = buf;
		mid->large_buf = true;
		server->bigbuf = NULL;
	}
	return true;
}

struct smb_version_operations smb1_operations = {
	.send_cancel = send_nt_cancel,
	.compare_fids = cifs_compare_fids,
	.setup_request = cifs_setup_request,
	.check_receive = cifs_check_receive,
	.add_credits = cifs_add_credits,
	.set_credits = cifs_set_credits,
	.get_credits_field = cifs_get_credits_field,
	.get_next_mid = cifs_get_next_mid,
	.read_data_offset = cifs_read_data_offset,
	.read_data_length = cifs_read_data_length,
	.map_error = map_smb_to_linux_error,
	.find_mid = cifs_find_mid,
	.check_message = checkSMB,
	.dump_detail = cifs_dump_detail,
	.is_oplock_break = is_valid_oplock_break,
	.check_trans2 = cifs_check_trans2,
};

struct smb_version_values smb1_values = {
	.version_string = SMB1_VERSION_STRING,
	.large_lock_type = LOCKING_ANDX_LARGE_FILES,
	.exclusive_lock_type = 0,
	.shared_lock_type = LOCKING_ANDX_SHARED_LOCK,
	.unlock_lock_type = 0,
	.header_size = sizeof(struct smb_hdr),
	.max_header_size = MAX_CIFS_HDR_SIZE,
	.read_rsp_size = sizeof(READ_RSP),
};