v4.19.13 snapshot.
diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
new file mode 100644
index 0000000..6b61df1
--- /dev/null
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -0,0 +1,386 @@
+/*
+ * Contains the CIFS DFS referral mounting routines used for handling
+ * traversal via DFS junction point
+ *
+ * Copyright (c) 2007 Igor Mammedov
+ * Copyright (C) International Business Machines Corp., 2008
+ * Author(s): Igor Mammedov (niallain@gmail.com)
+ * Steve French (sfrench@us.ibm.com)
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/dcache.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/slab.h>
+#include <linux/vfs.h>
+#include <linux/fs.h>
+#include <linux/inet.h>
+#include "cifsglob.h"
+#include "cifsproto.h"
+#include "cifsfs.h"
+#include "dns_resolve.h"
+#include "cifs_debug.h"
+#include "cifs_unicode.h"
+
+static LIST_HEAD(cifs_dfs_automount_list);
+
+static void cifs_dfs_expire_automounts(struct work_struct *work);
+static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
+ cifs_dfs_expire_automounts);
+static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
+
+static void cifs_dfs_expire_automounts(struct work_struct *work)
+{
+ struct list_head *list = &cifs_dfs_automount_list;
+
+ mark_mounts_for_expiry(list);
+ if (!list_empty(list))
+ schedule_delayed_work(&cifs_dfs_automount_task,
+ cifs_dfs_mountpoint_expiry_timeout);
+}
+
+void cifs_dfs_release_automount_timer(void)
+{
+ BUG_ON(!list_empty(&cifs_dfs_automount_list));
+ cancel_delayed_work_sync(&cifs_dfs_automount_task);
+}
+
+/**
+ * cifs_build_devname - build a devicename from a UNC and optional prepath
+ * @nodename: pointer to UNC string
+ * @prepath: pointer to prefixpath (or NULL if there isn't one)
+ *
+ * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
+ * big enough to hold the final thing. Copy the UNC from the nodename, and
+ * concatenate the prepath onto the end of it if there is one.
+ *
+ * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
+ * for freeing the returned string.
+ */
+static char *
+cifs_build_devname(char *nodename, const char *prepath)
+{
+ size_t pplen;
+ size_t unclen;
+ char *dev;
+ char *pos;
+
+ /* skip over any preceding delimiters */
+ nodename += strspn(nodename, "\\");
+ if (!*nodename)
+ return ERR_PTR(-EINVAL);
+
+ /* get length of UNC and set pos to last char */
+ unclen = strlen(nodename);
+ pos = nodename + unclen - 1;
+
+ /* trim off any trailing delimiters */
+ while (*pos == '\\') {
+ --pos;
+ --unclen;
+ }
+
+ /* allocate a buffer:
+ * +2 for preceding "//"
+ * +1 for delimiter between UNC and prepath
+ * +1 for trailing NULL
+ */
+ pplen = prepath ? strlen(prepath) : 0;
+ dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
+ if (!dev)
+ return ERR_PTR(-ENOMEM);
+
+ pos = dev;
+ /* add the initial "//" */
+ *pos = '/';
+ ++pos;
+ *pos = '/';
+ ++pos;
+
+ /* copy in the UNC portion from referral */
+ memcpy(pos, nodename, unclen);
+ pos += unclen;
+
+ /* copy the prefixpath remainder (if there is one) */
+ if (pplen) {
+ *pos = '/';
+ ++pos;
+ memcpy(pos, prepath, pplen);
+ pos += pplen;
+ }
+
+ /* NULL terminator */
+ *pos = '\0';
+
+ convert_delimiter(dev, '/');
+ return dev;
+}
+
+
+/**
+ * cifs_compose_mount_options - creates mount options for refferral
+ * @sb_mountdata: parent/root DFS mount options (template)
+ * @fullpath: full path in UNC format
+ * @ref: server's referral
+ * @devname: pointer for saving device name
+ *
+ * creates mount options for submount based on template options sb_mountdata
+ * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
+ *
+ * Returns: pointer to new mount options or ERR_PTR.
+ * Caller is responcible for freeing retunrned value if it is not error.
+ */
+char *cifs_compose_mount_options(const char *sb_mountdata,
+ const char *fullpath,
+ const struct dfs_info3_param *ref,
+ char **devname)
+{
+ int rc;
+ char *mountdata = NULL;
+ const char *prepath = NULL;
+ int md_len;
+ char *tkn_e;
+ char *srvIP = NULL;
+ char sep = ',';
+ int off, noff;
+
+ if (sb_mountdata == NULL)
+ return ERR_PTR(-EINVAL);
+
+ if (strlen(fullpath) - ref->path_consumed) {
+ prepath = fullpath + ref->path_consumed;
+ /* skip initial delimiter */
+ if (*prepath == '/' || *prepath == '\\')
+ prepath++;
+ }
+
+ *devname = cifs_build_devname(ref->node_name, prepath);
+ if (IS_ERR(*devname)) {
+ rc = PTR_ERR(*devname);
+ *devname = NULL;
+ goto compose_mount_options_err;
+ }
+
+ rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
+ if (rc < 0) {
+ cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
+ __func__, *devname, rc);
+ goto compose_mount_options_err;
+ }
+
+ /*
+ * In most cases, we'll be building a shorter string than the original,
+ * but we do have to assume that the address in the ip= option may be
+ * much longer than the original. Add the max length of an address
+ * string to the length of the original string to allow for worst case.
+ */
+ md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
+ mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
+ if (mountdata == NULL) {
+ rc = -ENOMEM;
+ goto compose_mount_options_err;
+ }
+
+ /* copy all options except of unc,ip,prefixpath */
+ off = 0;
+ if (strncmp(sb_mountdata, "sep=", 4) == 0) {
+ sep = sb_mountdata[4];
+ strncpy(mountdata, sb_mountdata, 5);
+ off += 5;
+ }
+
+ do {
+ tkn_e = strchr(sb_mountdata + off, sep);
+ if (tkn_e == NULL)
+ noff = strlen(sb_mountdata + off);
+ else
+ noff = tkn_e - (sb_mountdata + off) + 1;
+
+ if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
+ off += noff;
+ continue;
+ }
+ if (strncasecmp(sb_mountdata + off, "ip=", 3) == 0) {
+ off += noff;
+ continue;
+ }
+ if (strncasecmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
+ off += noff;
+ continue;
+ }
+ strncat(mountdata, sb_mountdata + off, noff);
+ off += noff;
+ } while (tkn_e);
+ strcat(mountdata, sb_mountdata + off);
+ mountdata[md_len] = '\0';
+
+ /* copy new IP and ref share name */
+ if (mountdata[strlen(mountdata) - 1] != sep)
+ strncat(mountdata, &sep, 1);
+ strcat(mountdata, "ip=");
+ strcat(mountdata, srvIP);
+
+ /*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
+ /*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
+
+compose_mount_options_out:
+ kfree(srvIP);
+ return mountdata;
+
+compose_mount_options_err:
+ kfree(mountdata);
+ mountdata = ERR_PTR(rc);
+ kfree(*devname);
+ *devname = NULL;
+ goto compose_mount_options_out;
+}
+
+/**
+ * cifs_dfs_do_refmount - mounts specified path using provided refferal
+ * @cifs_sb: parent/root superblock
+ * @fullpath: full path in UNC format
+ * @ref: server's referral
+ */
+static struct vfsmount *cifs_dfs_do_refmount(struct dentry *mntpt,
+ struct cifs_sb_info *cifs_sb,
+ const char *fullpath, const struct dfs_info3_param *ref)
+{
+ struct vfsmount *mnt;
+ char *mountdata;
+ char *devname = NULL;
+
+ /* strip first '\' from fullpath */
+ mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
+ fullpath + 1, ref, &devname);
+
+ if (IS_ERR(mountdata))
+ return (struct vfsmount *)mountdata;
+
+ mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
+ kfree(mountdata);
+ kfree(devname);
+ return mnt;
+
+}
+
+static void dump_referral(const struct dfs_info3_param *ref)
+{
+ cifs_dbg(FYI, "DFS: ref path: %s\n", ref->path_name);
+ cifs_dbg(FYI, "DFS: node path: %s\n", ref->node_name);
+ cifs_dbg(FYI, "DFS: fl: %hd, srv_type: %hd\n",
+ ref->flags, ref->server_type);
+ cifs_dbg(FYI, "DFS: ref_flags: %hd, path_consumed: %hd\n",
+ ref->ref_flag, ref->path_consumed);
+}
+
+/*
+ * Create a vfsmount that we can automount
+ */
+static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
+{
+ struct dfs_info3_param *referrals = NULL;
+ unsigned int num_referrals = 0;
+ struct cifs_sb_info *cifs_sb;
+ struct cifs_ses *ses;
+ char *full_path;
+ unsigned int xid;
+ int i;
+ int rc;
+ struct vfsmount *mnt;
+ struct tcon_link *tlink;
+
+ cifs_dbg(FYI, "in %s\n", __func__);
+ BUG_ON(IS_ROOT(mntpt));
+
+ /*
+ * The MSDFS spec states that paths in DFS referral requests and
+ * responses must be prefixed by a single '\' character instead of
+ * the double backslashes usually used in the UNC. This function
+ * gives us the latter, so we must adjust the result.
+ */
+ mnt = ERR_PTR(-ENOMEM);
+
+ /* always use tree name prefix */
+ full_path = build_path_from_dentry_optional_prefix(mntpt, true);
+ if (full_path == NULL)
+ goto cdda_exit;
+
+ cifs_sb = CIFS_SB(mntpt->d_sb);
+ tlink = cifs_sb_tlink(cifs_sb);
+ if (IS_ERR(tlink)) {
+ mnt = ERR_CAST(tlink);
+ goto free_full_path;
+ }
+ ses = tlink_tcon(tlink)->ses;
+
+ xid = get_xid();
+ rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
+ &num_referrals, &referrals,
+ cifs_remap(cifs_sb));
+ free_xid(xid);
+
+ cifs_put_tlink(tlink);
+
+ mnt = ERR_PTR(-ENOENT);
+ for (i = 0; i < num_referrals; i++) {
+ int len;
+ dump_referral(referrals + i);
+ /* connect to a node */
+ len = strlen(referrals[i].node_name);
+ if (len < 2) {
+ cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
+ __func__, referrals[i].node_name);
+ mnt = ERR_PTR(-EINVAL);
+ break;
+ }
+ mnt = cifs_dfs_do_refmount(mntpt, cifs_sb,
+ full_path, referrals + i);
+ cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n",
+ __func__, referrals[i].node_name, mnt);
+ if (!IS_ERR(mnt))
+ goto success;
+ }
+
+ /* no valid submounts were found; return error from get_dfs_path() by
+ * preference */
+ if (rc != 0)
+ mnt = ERR_PTR(rc);
+
+success:
+ free_dfs_info_array(referrals, num_referrals);
+free_full_path:
+ kfree(full_path);
+cdda_exit:
+ cifs_dbg(FYI, "leaving %s\n" , __func__);
+ return mnt;
+}
+
+/*
+ * Attempt to automount the referral
+ */
+struct vfsmount *cifs_dfs_d_automount(struct path *path)
+{
+ struct vfsmount *newmnt;
+
+ cifs_dbg(FYI, "in %s\n", __func__);
+
+ newmnt = cifs_dfs_do_automount(path->dentry);
+ if (IS_ERR(newmnt)) {
+ cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
+ return newmnt;
+ }
+
+ mntget(newmnt); /* prevent immediate expiration */
+ mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
+ schedule_delayed_work(&cifs_dfs_automount_task,
+ cifs_dfs_mountpoint_expiry_timeout);
+ cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
+ return newmnt;
+}
+
+const struct inode_operations cifs_dfs_referral_inode_operations = {
+};