/*
 *   fs/cifs/misc.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2008
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   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 <linux/slab.h>
#include <linux/ctype.h>
#include <linux/mempool.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "smberr.h"
#include "nterr.h"
#include "cifs_unicode.h"
#ifdef CONFIG_CIFS_SMB2
#include "smb2pdu.h"
#endif

extern mempool_t *cifs_sm_req_poolp;
extern mempool_t *cifs_req_poolp;

/* The xid serves as a useful identifier for each incoming vfs request,
   in a similar way to the mid which is useful to track each sent smb,
   and CurrentXid can also provide a running counter (although it
   will eventually wrap past zero) of the total vfs operations handled
   since the cifs fs was mounted */

unsigned int
_get_xid(void)
{
        unsigned int xid;

        spin_lock(&GlobalMid_Lock);
        GlobalTotalActiveXid++;

        /* keep high water mark for number of simultaneous ops in filesystem */
        if (GlobalTotalActiveXid > GlobalMaxActiveXid)
                GlobalMaxActiveXid = GlobalTotalActiveXid;
        if (GlobalTotalActiveXid > 65000)
                cifs_dbg(FYI, "warning: more than 65000 requests active\n");
        xid = GlobalCurrentXid++;
        spin_unlock(&GlobalMid_Lock);
        return xid;
}

void
_free_xid(unsigned int xid)
{
        spin_lock(&GlobalMid_Lock);
        /* if (GlobalTotalActiveXid == 0)
                BUG(); */
        GlobalTotalActiveXid--;
        spin_unlock(&GlobalMid_Lock);
}

struct cifs_ses *
sesInfoAlloc(void)
{
        struct cifs_ses *ret_buf;

        ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
        if (ret_buf) {
                atomic_inc(&sesInfoAllocCount);
                ret_buf->status = CifsNew;
                ++ret_buf->ses_count;
                INIT_LIST_HEAD(&ret_buf->smb_ses_list);
                INIT_LIST_HEAD(&ret_buf->tcon_list);
                mutex_init(&ret_buf->session_mutex);
        }
        return ret_buf;
}

void
sesInfoFree(struct cifs_ses *buf_to_free)
{
        if (buf_to_free == NULL) {
                cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
                return;
        }

        atomic_dec(&sesInfoAllocCount);
        kfree(buf_to_free->serverOS);
        kfree(buf_to_free->serverDomain);
        kfree(buf_to_free->serverNOS);
        if (buf_to_free->password) {
                memset(buf_to_free->password, 0, strlen(buf_to_free->password));
                kfree(buf_to_free->password);
        }
        kfree(buf_to_free->user_name);
        kfree(buf_to_free->domainName);
        kfree(buf_to_free->auth_key.response);
        kfree(buf_to_free);
}

struct cifs_tcon *
tconInfoAlloc(void)
{
        struct cifs_tcon *ret_buf;
        ret_buf = kzalloc(sizeof(struct cifs_tcon), GFP_KERNEL);
        if (ret_buf) {
                atomic_inc(&tconInfoAllocCount);
                ret_buf->tidStatus = CifsNew;
                ++ret_buf->tc_count;
                INIT_LIST_HEAD(&ret_buf->openFileList);
                INIT_LIST_HEAD(&ret_buf->tcon_list);
#ifdef CONFIG_CIFS_STATS
                spin_lock_init(&ret_buf->stat_lock);
#endif
        }
        return ret_buf;
}

void
tconInfoFree(struct cifs_tcon *buf_to_free)
{
        if (buf_to_free == NULL) {
                cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
                return;
        }
        atomic_dec(&tconInfoAllocCount);
        kfree(buf_to_free->nativeFileSystem);
        if (buf_to_free->password) {
                memset(buf_to_free->password, 0, strlen(buf_to_free->password));
                kfree(buf_to_free->password);
        }
        kfree(buf_to_free);
}

struct smb_hdr *
cifs_buf_get(void)
{
        struct smb_hdr *ret_buf = NULL;
        size_t buf_size = sizeof(struct smb_hdr);

#ifdef CONFIG_CIFS_SMB2
        /*
         * SMB2 header is bigger than CIFS one - no problems to clean some
         * more bytes for CIFS.
         */
        buf_size = sizeof(struct smb2_hdr);
#endif
        /*
         * We could use negotiated size instead of max_msgsize -
         * but it may be more efficient to always alloc same size
         * albeit slightly larger than necessary and maxbuffersize
         * defaults to this and can not be bigger.
         */
        ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);

        /* clear the first few header bytes */
        /* for most paths, more is cleared in header_assemble */
        if (ret_buf) {
                memset(ret_buf, 0, buf_size + 3);
                atomic_inc(&bufAllocCount);
#ifdef CONFIG_CIFS_STATS2
                atomic_inc(&totBufAllocCount);
#endif /* CONFIG_CIFS_STATS2 */
        }

        return ret_buf;
}

void
cifs_buf_release(void *buf_to_free)
{
        if (buf_to_free == NULL) {
                /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
                return;
        }
        mempool_free(buf_to_free, cifs_req_poolp);

        atomic_dec(&bufAllocCount);
        return;
}

struct smb_hdr *
cifs_small_buf_get(void)
{
        struct smb_hdr *ret_buf = NULL;

/* We could use negotiated size instead of max_msgsize -
   but it may be more efficient to always alloc same size
   albeit slightly larger than necessary and maxbuffersize
   defaults to this and can not be bigger */
        ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
        if (ret_buf) {
        /* No need to clear memory here, cleared in header assemble */
        /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
                atomic_inc(&smBufAllocCount);
#ifdef CONFIG_CIFS_STATS2
                atomic_inc(&totSmBufAllocCount);
#endif /* CONFIG_CIFS_STATS2 */

        }
        return ret_buf;
}

void
cifs_small_buf_release(void *buf_to_free)
{

        if (buf_to_free == NULL) {
                cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
                return;
        }
        mempool_free(buf_to_free, cifs_sm_req_poolp);

        atomic_dec(&smBufAllocCount);
        return;
}

void
free_rsp_buf(int resp_buftype, void *rsp)
{
        if (resp_buftype == CIFS_SMALL_BUFFER)
                cifs_small_buf_release(rsp);
        else if (resp_buftype == CIFS_LARGE_BUFFER)
                cifs_buf_release(rsp);
}

/* NB: MID can not be set if treeCon not passed in, in that
   case it is responsbility of caller to set the mid */
void
header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
                const struct cifs_tcon *treeCon, int word_count
                /* length of fixed section (word count) in two byte units  */)
{
        char *temp = (char *) buffer;

        memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */

        buffer->smb_buf_length = cpu_to_be32(
            (2 * word_count) + sizeof(struct smb_hdr) -
            4 /*  RFC 1001 length field does not count */  +
            2 /* for bcc field itself */) ;

        buffer->Protocol[0] = 0xFF;
        buffer->Protocol[1] = 'S';
        buffer->Protocol[2] = 'M';
        buffer->Protocol[3] = 'B';
        buffer->Command = smb_command;
        buffer->Flags = 0x00;   /* case sensitive */
        buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
        buffer->Pid = cpu_to_le16((__u16)current->tgid);
        buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
        if (treeCon) {
                buffer->Tid = treeCon->tid;
                if (treeCon->ses) {
                        if (treeCon->ses->capabilities & CAP_UNICODE)
                                buffer->Flags2 |= SMBFLG2_UNICODE;
                        if (treeCon->ses->capabilities & CAP_STATUS32)
                                buffer->Flags2 |= SMBFLG2_ERR_STATUS;

                        /* Uid is not converted */
                        buffer->Uid = treeCon->ses->Suid;
                        buffer->Mid = get_next_mid(treeCon->ses->server);
                }
                if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
                        buffer->Flags2 |= SMBFLG2_DFS;
                if (treeCon->nocase)
                        buffer->Flags  |= SMBFLG_CASELESS;
                if ((treeCon->ses) && (treeCon->ses->server))
                        if (treeCon->ses->server->sign)
                                buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
        }

/*  endian conversion of flags is now done just before sending */
        buffer->WordCount = (char) word_count;
        return;
}

static int
check_smb_hdr(struct smb_hdr *smb)
{
        /* does it have the right SMB "signature" ? */
        if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
                cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
                         *(unsigned int *)smb->Protocol);
                return 1;
        }

        /* if it's a response then accept */
        if (smb->Flags & SMBFLG_RESPONSE)
                return 0;

        /* only one valid case where server sends us request */
        if (smb->Command == SMB_COM_LOCKING_ANDX)
                return 0;

        cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
                 get_mid(smb));
        return 1;
}

int
checkSMB(char *buf, unsigned int total_read)
{
        struct smb_hdr *smb = (struct smb_hdr *)buf;
        __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
        __u32 clc_len;  /* calculated length */
        cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
                 total_read, rfclen);

        /* is this frame too small to even get to a BCC? */
        if (total_read < 2 + sizeof(struct smb_hdr)) {
                if ((total_read >= sizeof(struct smb_hdr) - 1)
                            && (smb->Status.CifsError != 0)) {
                        /* it's an error return */
                        smb->WordCount = 0;
                        /* some error cases do not return wct and bcc */
                        return 0;
                } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
                                (smb->WordCount == 0)) {
                        char *tmp = (char *)smb;
                        /* Need to work around a bug in two servers here */
                        /* First, check if the part of bcc they sent was zero */
                        if (tmp[sizeof(struct smb_hdr)] == 0) {
                                /* some servers return only half of bcc
                                 * on simple responses (wct, bcc both zero)
                                 * in particular have seen this on
                                 * ulogoffX and FindClose. This leaves
                                 * one byte of bcc potentially unitialized
                                 */
                                /* zero rest of bcc */
                                tmp[sizeof(struct smb_hdr)+1] = 0;
                                return 0;
                        }
                        cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
                } else {
                        cifs_dbg(VFS, "Length less than smb header size\n");
                }
                return -EIO;
        }

        /* otherwise, there is enough to get to the BCC */
        if (check_smb_hdr(smb))
                return -EIO;
        clc_len = smbCalcSize(smb);

        if (4 + rfclen != total_read) {
                cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
                         rfclen);
                return -EIO;
        }

        if (4 + rfclen != clc_len) {
                __u16 mid = get_mid(smb);
                /* check if bcc wrapped around for large read responses */
                if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
                        /* check if lengths match mod 64K */
                        if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
                                return 0; /* bcc wrapped */
                }
                cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
                         clc_len, 4 + rfclen, mid);

                if (4 + rfclen < clc_len) {
                        cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
                                 rfclen, mid);
                        return -EIO;
                } else if (rfclen > clc_len + 512) {
                        /*
                         * Some servers (Windows XP in particular) send more
                         * data than the lengths in the SMB packet would
                         * indicate on certain calls (byte range locks and
                         * trans2 find first calls in particular). While the
                         * client can handle such a frame by ignoring the
                         * trailing data, we choose limit the amount of extra
                         * data to 512 bytes.
                         */
                        cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
                                 rfclen, mid);
                        return -EIO;
                }
        }
        return 0;
}

bool
is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
{
        struct smb_hdr *buf = (struct smb_hdr *)buffer;
        struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
        struct list_head *tmp, *tmp1, *tmp2;
        struct cifs_ses *ses;
        struct cifs_tcon *tcon;
        struct cifsInodeInfo *pCifsInode;
        struct cifsFileInfo *netfile;

        cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
        if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
           (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
                struct smb_com_transaction_change_notify_rsp *pSMBr =
                        (struct smb_com_transaction_change_notify_rsp *)buf;
                struct file_notify_information *pnotify;
                __u32 data_offset = 0;
                if (get_bcc(buf) > sizeof(struct file_notify_information)) {
                        data_offset = le32_to_cpu(pSMBr->DataOffset);

                        pnotify = (struct file_notify_information *)
                                ((char *)&pSMBr->hdr.Protocol + data_offset);
                        cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
                                 pnotify->FileName, pnotify->Action);
                        /*   cifs_dump_mem("Rcvd notify Data: ",buf,
                                sizeof(struct smb_hdr)+60); */
                        return true;
                }
                if (pSMBr->hdr.Status.CifsError) {
                        cifs_dbg(FYI, "notify err 0x%x\n",
                                 pSMBr->hdr.Status.CifsError);
                        return true;
                }
                return false;
        }
        if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
                return false;
        if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
                /* no sense logging error on invalid handle on oplock
                   break - harmless race between close request and oplock
                   break response is expected from time to time writing out
                   large dirty files cached on the client */
                if ((NT_STATUS_INVALID_HANDLE) ==
                   le32_to_cpu(pSMB->hdr.Status.CifsError)) {
                        cifs_dbg(FYI, "invalid handle on oplock break\n");
                        return true;
                } else if (ERRbadfid ==
                   le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
                        return true;
                } else {
                        return false; /* on valid oplock brk we get "request" */
                }
        }
        if (pSMB->hdr.WordCount != 8)
                return false;

        cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
                 pSMB->LockType, pSMB->OplockLevel);
        if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
                return false;

        /* look up tcon based on tid & uid */
        spin_lock(&cifs_tcp_ses_lock);
        list_for_each(tmp, &srv->smb_ses_list) {
                ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
                list_for_each(tmp1, &ses->tcon_list) {
                        tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
                        if (tcon->tid != buf->Tid)
                                continue;

                        cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
                        spin_lock(&cifs_file_list_lock);
                        list_for_each(tmp2, &tcon->openFileList) {
                                netfile = list_entry(tmp2, struct cifsFileInfo,
                                                     tlist);
                                if (pSMB->Fid != netfile->fid.netfid)
                                        continue;

                                cifs_dbg(FYI, "file id match, oplock break\n");
                                pCifsInode = CIFS_I(d_inode(netfile->dentry));

                                set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
                                        &pCifsInode->flags);

                                /*
                                 * Set flag if the server downgrades the oplock
                                 * to L2 else clear.
                                 */
                                if (pSMB->OplockLevel)
                                        set_bit(
                                           CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
                                           &pCifsInode->flags);
                                else
                                        clear_bit(
                                           CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
                                           &pCifsInode->flags);

                                queue_work(cifsiod_wq,
                                           &netfile->oplock_break);
                                netfile->oplock_break_cancelled = false;

                                spin_unlock(&cifs_file_list_lock);
                                spin_unlock(&cifs_tcp_ses_lock);
                                return true;
                        }
                        spin_unlock(&cifs_file_list_lock);
                        spin_unlock(&cifs_tcp_ses_lock);
                        cifs_dbg(FYI, "No matching file for oplock break\n");
                        return true;
                }
        }
        spin_unlock(&cifs_tcp_ses_lock);
        cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
        return true;
}

void
dump_smb(void *buf, int smb_buf_length)
{
        if (traceSMB == 0)
                return;

        print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
                       smb_buf_length, true);
}

void
cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
{
        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
                cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
                cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s. This server doesn't seem to support them properly. Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n",
                         cifs_sb_master_tcon(cifs_sb)->treeName);
        }
}

void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
{
        oplock &= 0xF;

        if (oplock == OPLOCK_EXCLUSIVE) {
                cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
                cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
                         &cinode->vfs_inode);
        } else if (oplock == OPLOCK_READ) {
                cinode->oplock = CIFS_CACHE_READ_FLG;
                cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
                         &cinode->vfs_inode);
        } else
                cinode->oplock = 0;
}

/*
 * We wait for oplock breaks to be processed before we attempt to perform
 * writes.
 */
int cifs_get_writer(struct cifsInodeInfo *cinode)
{
        int rc;

start:
        rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
                         TASK_KILLABLE);
        if (rc)
                return rc;

        spin_lock(&cinode->writers_lock);
        if (!cinode->writers)
                set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
        cinode->writers++;
        /* Check to see if we have started servicing an oplock break */
        if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
                cinode->writers--;
                if (cinode->writers == 0) {
                        clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
                        wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
                }
                spin_unlock(&cinode->writers_lock);
                goto start;
        }
        spin_unlock(&cinode->writers_lock);
        return 0;
}

void cifs_put_writer(struct cifsInodeInfo *cinode)
{
        spin_lock(&cinode->writers_lock);
        cinode->writers--;
        if (cinode->writers == 0) {
                clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
                wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
        }
        spin_unlock(&cinode->writers_lock);
}

void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
{
        clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
        wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
}

bool
backup_cred(struct cifs_sb_info *cifs_sb)
{
        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
                if (uid_eq(cifs_sb->mnt_backupuid, current_fsuid()))
                        return true;
        }
        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
                if (in_group_p(cifs_sb->mnt_backupgid))
                        return true;
        }

        return false;
}

void
cifs_del_pending_open(struct cifs_pending_open *open)
{
        spin_lock(&cifs_file_list_lock);
        list_del(&open->olist);
        spin_unlock(&cifs_file_list_lock);
}

void
cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
                             struct cifs_pending_open *open)
{
#ifdef CONFIG_CIFS_SMB2
        memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
#endif
        open->oplock = CIFS_OPLOCK_NO_CHANGE;
        open->tlink = tlink;
        fid->pending_open = open;
        list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
}

void
cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
                      struct cifs_pending_open *open)
{
        spin_lock(&cifs_file_list_lock);
        cifs_add_pending_open_locked(fid, tlink, open);
        spin_unlock(&cifs_file_list_lock);
}