// SPDX-License-Identifier: LGPL-2.1
/*
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2008
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 */
#include <crypto/md5.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include "cifsfs.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifs_fs_sb.h"
#include "cifs_unicode.h"
#include "smb2proto.h"
#include "cifs_ioctl.h"
#include "fs_context.h"
#include "reparse.h"

/*
 * M-F Symlink Functions - Begin
 */

#define CIFS_MF_SYMLINK_LEN_OFFSET (4+1)
#define CIFS_MF_SYMLINK_MD5_OFFSET (CIFS_MF_SYMLINK_LEN_OFFSET+(4+1))
#define CIFS_MF_SYMLINK_LINK_OFFSET (CIFS_MF_SYMLINK_MD5_OFFSET+(32+1))
#define CIFS_MF_SYMLINK_LINK_MAXLEN (1024)
#define CIFS_MF_SYMLINK_FILE_SIZE \
        (CIFS_MF_SYMLINK_LINK_OFFSET + CIFS_MF_SYMLINK_LINK_MAXLEN)

#define CIFS_MF_SYMLINK_LEN_FORMAT "XSym\n%04u\n"
#define CIFS_MF_SYMLINK_MD5_FORMAT "%16phN\n"
#define CIFS_MF_SYMLINK_MD5_ARGS(md5_hash) md5_hash

static int
parse_mf_symlink(const u8 *buf, unsigned int buf_len, unsigned int *_link_len,
                 char **_link_str)
{
        int rc;
        unsigned int link_len;
        const char *md5_str1;
        const char *link_str;
        u8 md5_hash[16];
        char md5_str2[34];

        if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
                return -EINVAL;

        md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
        link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];

        rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
        if (rc != 1)
                return -EINVAL;

        if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
                return -EINVAL;

        md5(link_str, link_len, md5_hash);

        scnprintf(md5_str2, sizeof(md5_str2),
                  CIFS_MF_SYMLINK_MD5_FORMAT,
                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));

        if (strncmp(md5_str1, md5_str2, 17) != 0)
                return -EINVAL;

        if (_link_str) {
                *_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
                if (!*_link_str)
                        return -ENOMEM;
        }

        *_link_len = link_len;
        return 0;
}

static int
format_mf_symlink(u8 *buf, unsigned int buf_len, const char *link_str)
{
        unsigned int link_len;
        unsigned int ofs;
        u8 md5_hash[16];

        if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
                return -EINVAL;

        link_len = strlen(link_str);

        if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
                return -ENAMETOOLONG;

        md5(link_str, link_len, md5_hash);

        scnprintf(buf, buf_len,
                  CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
                  link_len,
                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));

        ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
        memcpy(buf + ofs, link_str, link_len);

        ofs += link_len;
        if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
                buf[ofs] = '\n';
                ofs++;
        }

        while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
                buf[ofs] = ' ';
                ofs++;
        }

        return 0;
}

bool
couldbe_mf_symlink(const struct cifs_fattr *fattr)
{
        if (!S_ISREG(fattr->cf_mode))
                /* it's not a symlink */
                return false;

        if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
                /* it's not a symlink */
                return false;

        return true;
}

static int
create_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
                  struct cifs_sb_info *cifs_sb, const char *fromName,
                  const char *toName)
{
        int rc;
        u8 *buf;
        unsigned int bytes_written = 0;

        buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        rc = format_mf_symlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
        if (rc)
                goto out;

        if (tcon->ses->server->ops->create_mf_symlink)
                rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon,
                                        cifs_sb, fromName, buf, &bytes_written);
        else
                rc = -EOPNOTSUPP;

        if (rc)
                goto out;

        if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
                rc = smb_EIO2(smb_eio_trace_symlink_file_size,
                              bytes_written, CIFS_MF_SYMLINK_FILE_SIZE);
out:
        kfree(buf);
        return rc;
}

int
check_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
                 struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
                 const unsigned char *path)
{
        int rc;
        u8 *buf = NULL;
        unsigned int link_len = 0;
        unsigned int bytes_read = 0;
        char *symlink = NULL;

        if (!couldbe_mf_symlink(fattr))
                /* it's not a symlink */
                return 0;

        buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        if (tcon->ses->server->ops->query_mf_symlink)
                rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
                                              cifs_sb, path, buf, &bytes_read);
        else
                rc = -ENOSYS;

        if (rc)
                goto out;

        if (bytes_read == 0) /* not a symlink */
                goto out;

        rc = parse_mf_symlink(buf, bytes_read, &link_len, &symlink);
        if (rc == -EINVAL) {
                /* it's not a symlink */
                rc = 0;
                goto out;
        }

        if (rc != 0)
                goto out;

        /* it is a symlink */
        fattr->cf_eof = link_len;
        fattr->cf_mode &= ~S_IFMT;
        fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
        fattr->cf_dtype = DT_LNK;
        fattr->cf_symlink_target = symlink;
out:
        kfree(buf);
        return rc;
}

#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
/*
 * SMB 1.0 Protocol specific functions
 */

int
cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
                      struct cifs_sb_info *cifs_sb, const unsigned char *path,
                      char *pbuf, unsigned int *pbytes_read)
{
        int rc;
        int oplock = 0;
        struct cifs_fid fid;
        struct cifs_open_parms oparms;
        struct cifs_io_parms io_parms = {0};
        int buf_type = CIFS_NO_BUFFER;
        struct cifs_open_info_data query_data;

        oparms = (struct cifs_open_parms) {
                .tcon = tcon,
                .cifs_sb = cifs_sb,
                .desired_access = GENERIC_READ,
                .create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR),
                .disposition = FILE_OPEN,
                .path = path,
                .fid = &fid,
        };

        rc = tcon->ses->server->ops->open(xid, &oparms, &oplock, &query_data);
        if (rc)
                return rc;

        if (query_data.fi.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
                rc = -ENOENT;
                /* it's not a symlink */
                goto out;
        }

        io_parms.netfid = fid.netfid;
        io_parms.pid = current->tgid;
        io_parms.tcon = tcon;
        io_parms.offset = 0;
        io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;

        rc = CIFSSMBRead(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
out:
        CIFSSMBClose(xid, tcon, fid.netfid);
        return rc;
}

int
cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
                       struct cifs_sb_info *cifs_sb, const unsigned char *path,
                       char *pbuf, unsigned int *pbytes_written)
{
        int rc;
        int oplock = 0;
        struct cifs_fid fid;
        struct cifs_open_parms oparms;
        struct cifs_io_parms io_parms = {0};

        oparms = (struct cifs_open_parms) {
                .tcon = tcon,
                .cifs_sb = cifs_sb,
                .desired_access = GENERIC_WRITE,
                .create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR),
                .disposition = FILE_CREATE,
                .path = path,
                .fid = &fid,
        };

        rc = tcon->ses->server->ops->open(xid, &oparms, &oplock, NULL);
        if (rc)
                return rc;

        io_parms.netfid = fid.netfid;
        io_parms.pid = current->tgid;
        io_parms.tcon = tcon;
        io_parms.offset = 0;
        io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;

        rc = CIFSSMBWrite(xid, &io_parms, pbytes_written, pbuf);
        CIFSSMBClose(xid, tcon, fid.netfid);
        return rc;
}
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */

/*
 * SMB 2.1/SMB3 Protocol specific functions
 */
int
smb3_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
                      struct cifs_sb_info *cifs_sb, const unsigned char *path,
                      char *pbuf, unsigned int *pbytes_read)
{
        int rc;
        struct cifs_fid fid;
        struct cifs_open_parms oparms;
        struct cifs_io_parms io_parms = {0};
        int buf_type = CIFS_NO_BUFFER;
        __le16 *utf16_path;
        __u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
        struct smb2_file_all_info *pfile_info = NULL;

        oparms = (struct cifs_open_parms) {
                .tcon = tcon,
                .cifs_sb = cifs_sb,
                .path = path,
                .desired_access = GENERIC_READ,
                .create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR),
                .disposition = FILE_OPEN,
                .fid = &fid,
        };

        utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
        if (utf16_path == NULL)
                return -ENOMEM;

        pfile_info = kzalloc(sizeof(struct smb2_file_all_info) + PATH_MAX * 2,
                             GFP_KERNEL);

        if (pfile_info == NULL) {
                kfree(utf16_path);
                return  -ENOMEM;
        }

        rc = SMB2_open(xid, &oparms, utf16_path, &oplock, pfile_info, NULL,
                       NULL, NULL);
        if (rc)
                goto qmf_out_open_fail;

        if (pfile_info->EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
                /* it's not a symlink */
                rc = -ENOENT; /* Is there a better rc to return? */
                goto qmf_out;
        }

        io_parms.netfid = fid.netfid;
        io_parms.pid = current->tgid;
        io_parms.tcon = tcon;
        io_parms.offset = 0;
        io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
        io_parms.persistent_fid = fid.persistent_fid;
        io_parms.volatile_fid = fid.volatile_fid;
        rc = SMB2_read(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
qmf_out:
        SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
qmf_out_open_fail:
        kfree(utf16_path);
        kfree(pfile_info);
        return rc;
}

int
smb3_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
                       struct cifs_sb_info *cifs_sb, const unsigned char *path,
                       char *pbuf, unsigned int *pbytes_written)
{
        int rc;
        struct cifs_fid fid;
        struct cifs_open_parms oparms;
        struct cifs_io_parms io_parms = {0};
        __le16 *utf16_path;
        __u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
        struct kvec iov[2];

        cifs_dbg(FYI, "%s: path: %s\n", __func__, path);

        utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
        if (!utf16_path)
                return -ENOMEM;

        oparms = (struct cifs_open_parms) {
                .tcon = tcon,
                .cifs_sb = cifs_sb,
                .path = path,
                .desired_access = GENERIC_WRITE,
                .create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR),
                .disposition = FILE_CREATE,
                .fid = &fid,
                .mode = 0644,
        };

        rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL,
                       NULL, NULL);
        if (rc) {
                kfree(utf16_path);
                return rc;
        }

        io_parms.netfid = fid.netfid;
        io_parms.pid = current->tgid;
        io_parms.tcon = tcon;
        io_parms.offset = 0;
        io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
        io_parms.persistent_fid = fid.persistent_fid;
        io_parms.volatile_fid = fid.volatile_fid;

        /* iov[0] is reserved for smb header */
        iov[1].iov_base = pbuf;
        iov[1].iov_len = CIFS_MF_SYMLINK_FILE_SIZE;

        rc = SMB2_write(xid, &io_parms, pbytes_written, iov, 1);

        /* Make sure we wrote all of the symlink data */
        if ((rc == 0) && (*pbytes_written != CIFS_MF_SYMLINK_FILE_SIZE))
                rc = smb_EIO2(smb_eio_trace_short_symlink_write,
                              *pbytes_written, CIFS_MF_SYMLINK_FILE_SIZE);

        SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);

        kfree(utf16_path);
        return rc;
}

/*
 * M-F Symlink Functions - End
 */

int
cifs_hardlink(struct dentry *old_file, struct inode *inode,
              struct dentry *direntry)
{
        int rc = -EACCES;
        unsigned int xid;
        const char *from_name, *to_name;
        void *page1, *page2;
        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
        struct tcon_link *tlink;
        struct cifs_tcon *tcon;
        struct TCP_Server_Info *server;
        struct cifsInodeInfo *cifsInode;

        if (unlikely(cifs_forced_shutdown(cifs_sb)))
                return smb_EIO(smb_eio_trace_forced_shutdown);

        tlink = cifs_sb_tlink(cifs_sb);
        if (IS_ERR(tlink))
                return PTR_ERR(tlink);
        tcon = tlink_tcon(tlink);

        xid = get_xid();
        page1 = alloc_dentry_path();
        page2 = alloc_dentry_path();

        from_name = build_path_from_dentry(old_file, page1);
        if (IS_ERR(from_name)) {
                rc = PTR_ERR(from_name);
                goto cifs_hl_exit;
        }
        to_name = build_path_from_dentry(direntry, page2);
        if (IS_ERR(to_name)) {
                rc = PTR_ERR(to_name);
                goto cifs_hl_exit;
        }

#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
        if (tcon->unix_ext)
                rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
                                            cifs_sb->local_nls,
                                            cifs_remap(cifs_sb));
        else {
#else
        {
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
                server = tcon->ses->server;
                if (!server->ops->create_hardlink) {
                        rc = -ENOSYS;
                        goto cifs_hl_exit;
                }
                rc = server->ops->create_hardlink(xid, tcon, old_file,
                                                  from_name, to_name, cifs_sb);
                if ((rc == -EIO) || (rc == -EINVAL))
                        rc = -EOPNOTSUPP;
        }

        d_drop(direntry);       /* force new lookup from server of target */

        /*
         * if source file is cached (oplocked) revalidate will not go to server
         * until the file is closed or oplock broken so update nlinks locally
         */
        if (d_really_is_positive(old_file)) {
                cifsInode = CIFS_I(d_inode(old_file));
                if (rc == 0) {
                        spin_lock(&d_inode(old_file)->i_lock);
                        inc_nlink(d_inode(old_file));
                        spin_unlock(&d_inode(old_file)->i_lock);

                        /*
                         * parent dir timestamps will update from srv within a
                         * second, would it really be worth it to set the parent
                         * dir cifs inode time to zero to force revalidate
                         * (faster) for it too?
                         */
                }
                /*
                 * if not oplocked will force revalidate to get info on source
                 * file from srv.  Note Samba server prior to 4.2 has bug -
                 * not updating src file ctime on hardlinks but Windows servers
                 * handle it properly
                 */
                cifsInode->time = 0;

                /*
                 * Will update parent dir timestamps from srv within a second.
                 * Would it really be worth it to set the parent dir (cifs
                 * inode) time field to zero to force revalidate on parent
                 * directory faster ie
                 *
                 * CIFS_I(inode)->time = 0;
                 */
        }

cifs_hl_exit:
        free_dentry_path(page1);
        free_dentry_path(page2);
        free_xid(xid);
        cifs_put_tlink(tlink);
        return rc;
}

int
cifs_symlink(struct mnt_idmap *idmap, struct inode *inode,
             struct dentry *direntry, const char *symname)
{
        struct cifs_sb_info *cifs_sb = CIFS_SB(inode);
        struct inode *newinode = NULL;
        struct tcon_link *tlink;
        struct cifs_tcon *pTcon;
        const char *full_path;
        int rc = -EOPNOTSUPP;
        unsigned int sbflags;
        unsigned int xid;
        void *page;

        if (unlikely(cifs_forced_shutdown(cifs_sb)))
                return smb_EIO(smb_eio_trace_forced_shutdown);

        page = alloc_dentry_path();
        if (!page)
                return -ENOMEM;

        xid = get_xid();

        tlink = cifs_sb_tlink(cifs_sb);
        if (IS_ERR(tlink)) {
                rc = PTR_ERR(tlink);
                /* BB could be clearer if skipped put_tlink on error here, but harmless */
                goto symlink_exit;
        }
        pTcon = tlink_tcon(tlink);

        full_path = build_path_from_dentry(direntry, page);
        if (IS_ERR(full_path)) {
                rc = PTR_ERR(full_path);
                goto symlink_exit;
        }

        cifs_dbg(FYI, "Full path: %s\n", full_path);
        cifs_dbg(FYI, "symname is %s\n", symname);

        /* BB what if DFS and this volume is on different share? BB */
        sbflags = cifs_sb_flags(cifs_sb);
        rc = -EOPNOTSUPP;
        switch (cifs_symlink_type(cifs_sb)) {
        case CIFS_SYMLINK_TYPE_UNIX:
#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
                if (pTcon->unix_ext) {
                        rc = CIFSUnixCreateSymLink(xid, pTcon, full_path,
                                                   symname,
                                                   cifs_sb->local_nls,
                                                   cifs_remap(cifs_sb));
                }
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
                break;

        case CIFS_SYMLINK_TYPE_MFSYMLINKS:
                if (sbflags & CIFS_MOUNT_MF_SYMLINKS) {
                        rc = create_mf_symlink(xid, pTcon, cifs_sb,
                                               full_path, symname);
                }
                break;

        case CIFS_SYMLINK_TYPE_SFU:
                if (sbflags & CIFS_MOUNT_UNX_EMUL) {
                        rc = __cifs_sfu_make_node(xid, inode, direntry, pTcon,
                                                  full_path, S_IFLNK,
                                                  0, symname);
                }
                break;

        case CIFS_SYMLINK_TYPE_NATIVE:
        case CIFS_SYMLINK_TYPE_NFS:
        case CIFS_SYMLINK_TYPE_WSL:
                if (CIFS_REPARSE_SUPPORT(pTcon)) {
                        rc = create_reparse_symlink(xid, inode, direntry, pTcon,
                                                    full_path, symname);
                        goto symlink_exit;
                }
                break;
        default:
                break;
        }

        if (rc == 0) {
                if (pTcon->posix_extensions) {
                        rc = smb311_posix_get_inode_info(&newinode, full_path,
                                                         NULL, inode->i_sb, xid);
                } else if (pTcon->unix_ext) {
                        rc = cifs_get_inode_info_unix(&newinode, full_path,
                                                      inode->i_sb, xid);
                } else {
                        rc = cifs_get_inode_info(&newinode, full_path, NULL,
                                                 inode->i_sb, xid, NULL);
                }

                if (rc != 0) {
                        cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",
                                 rc);
                } else {
                        d_instantiate(direntry, newinode);
                }
        }
symlink_exit:
        free_dentry_path(page);
        cifs_put_tlink(tlink);
        free_xid(xid);
        return rc;
}