Fixed MTP to work with TWRP

fs/cifs/cifs_dfs_ref.c

@@ -0,0 +1,378 @@
+/*
+ *   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"
+
+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;
+
+	*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 + 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 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_kern_mount(&cifs_fs_type, 0, 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);
+	full_path = build_path_from_dentry(mntpt);
+	if (full_path == NULL)
+		goto cdda_exit;
+
+	cifs_sb = CIFS_SB(mntpt->d_inode->i_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_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
+	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(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 = {
+};