[linux-2.6-block.git] / fs / cifs / cifs_dfs_ref.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   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)
 */

#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"
#include "dfs_cache.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:		optional 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 *name;
	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++;
	}

	name = cifs_build_devname(ref->node_name, prepath);
	if (IS_ERR(name)) {
		rc = PTR_ERR(name);
		name = NULL;
		goto compose_mount_options_err;
	}

	rc = dns_resolve_server_name_to_ip(name, &srvIP);
	if (rc < 0) {
		cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
			 __func__, name, 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);

	if (devname)
		*devname = name;

	/*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(name);
	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;

	/*
	 * Always pass down the DFS full path to smb3_do_mount() so we
	 * can use it later for failover.
	 */
	devname = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);
	if (!devname)
		return ERR_PTR(-ENOMEM);

	convert_delimiter(devname, '/');

	/* strip first '\' from fullpath */
	mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
					       fullpath + 1, ref, NULL);
	if (IS_ERR(mountdata)) {
		kfree(devname);
		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: %d, srv_type: %d\n",
		 ref->flags, ref->server_type);
	cifs_dbg(FYI, "DFS: ref_flags: %d, path_consumed: %d\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 referral = {0};
	struct cifs_sb_info *cifs_sb;
	struct cifs_ses *ses;
	struct cifs_tcon *tcon;
	char *full_path, *root_path;
	unsigned int xid;
	int len;
	int rc;
	struct vfsmount *mnt;

	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);

	cifs_sb = CIFS_SB(mntpt->d_sb);
	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) {
		mnt = ERR_PTR(-EREMOTE);
		goto cdda_exit;
	}

	/* always use tree name prefix */
	full_path = build_path_from_dentry_optional_prefix(mntpt, true);
	if (full_path == NULL)
		goto cdda_exit;

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

	if (!cifs_sb_master_tlink(cifs_sb)) {
		cifs_dbg(FYI, "%s: master tlink is NULL\n", __func__);
		goto free_full_path;
	}

	tcon = cifs_sb_master_tcon(cifs_sb);
	if (!tcon) {
		cifs_dbg(FYI, "%s: master tcon is NULL\n", __func__);
		goto free_full_path;
	}

	root_path = kstrdup(tcon->treeName, GFP_KERNEL);
	if (!root_path) {
		mnt = ERR_PTR(-ENOMEM);
		goto free_full_path;
	}
	cifs_dbg(FYI, "%s: root path: %s\n", __func__, root_path);

	ses = tcon->ses;
	xid = get_xid();

	/*
	 * If DFS root has been expired, then unconditionally fetch it again to
	 * refresh DFS referral cache.
	 */
	rc = dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
			    root_path + 1, NULL, NULL);
	if (!rc) {
		rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,
				    cifs_remap(cifs_sb), full_path + 1,
				    &referral, NULL);
	}

	free_xid(xid);

	if (rc) {
		mnt = ERR_PTR(rc);
		goto free_root_path;
	}

	dump_referral(&referral);

	len = strlen(referral.node_name);
	if (len < 2) {
		cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
			 __func__, referral.node_name);
		mnt = ERR_PTR(-EINVAL);
		goto free_dfs_ref;
	}
	/*
	 * cifs_mount() will retry every available node server in case
	 * of failures.
	 */
	mnt = cifs_dfs_do_refmount(mntpt, cifs_sb, full_path, &referral);
	cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n", __func__,
		 referral.node_name, mnt);

free_dfs_ref:
	free_dfs_info_param(&referral);
free_root_path:
	kfree(root_path);
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 = {
};
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
6d5ae0de IM	2	/*
	3	* Contains the CIFS DFS referral mounting routines used for handling
	4	* traversal via DFS junction point
	5	*
	6	* Copyright (c) 2007 Igor Mammedov
366781c1	7	* Copyright (C) International Business Machines Corp., 2008
6d5ae0de	8	* Author(s): Igor Mammedov (niallain@gmail.com)
366781c1	9	* Steve French (sfrench@us.ibm.com)
6d5ae0de IM	10	*/
	11
	12	#include <linux/dcache.h>
	13	#include <linux/mount.h>
	14	#include <linux/namei.h>
5a0e3ad6	15	#include <linux/slab.h>
6d5ae0de IM	16	#include <linux/vfs.h>
6d5ae0de IM	17	#include <linux/fs.h>
166faf21	18	#include <linux/inet.h>
6d5ae0de IM	19	#include "cifsglob.h"
	20	#include "cifsproto.h"
	21	#include "cifsfs.h"
	22	#include "dns_resolve.h"
	23	#include "cifs_debug.h"
bc8ebdc4	24	#include "cifs_unicode.h"
1c780228	25	#include "dfs_cache.h"
6d5ae0de	26
8d142137	27	static LIST_HEAD(cifs_dfs_automount_list);
6d5ae0de	28
78d31a3a IM	29	static void cifs_dfs_expire_automounts(struct work_struct *work);
	30	static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
	31	cifs_dfs_expire_automounts);
	32	static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
	33
	34	static void cifs_dfs_expire_automounts(struct work_struct *work)
	35	{
	36	struct list_head *list = &cifs_dfs_automount_list;
	37
	38	mark_mounts_for_expiry(list);
	39	if (!list_empty(list))
	40	schedule_delayed_work(&cifs_dfs_automount_task,
	41	cifs_dfs_mountpoint_expiry_timeout);
	42	}
6d5ae0de	43
78d31a3a	44	void cifs_dfs_release_automount_timer(void)
6d5ae0de	45	{
78d31a3a	46	BUG_ON(!list_empty(&cifs_dfs_automount_list));
3e24e132	47	cancel_delayed_work_sync(&cifs_dfs_automount_task);
6d5ae0de IM	48	}
	49
	50	/**
d9deef0a JL	51	* cifs_build_devname - build a devicename from a UNC and optional prepath
	52	* @nodename: pointer to UNC string
	53	* @prepath: pointer to prefixpath (or NULL if there isn't one)
6d5ae0de	54	*
d9deef0a JL	55	* Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
	56	* big enough to hold the final thing. Copy the UNC from the nodename, and
	57	* concatenate the prepath onto the end of it if there is one.
	58	*
	59	* Returns pointer to the built string, or a ERR_PTR. Caller is responsible
	60	* for freeing the returned string.
6d5ae0de	61	*/
d9deef0a JL	62	static char *
d9deef0a JL	63	cifs_build_devname(char nodename, const char prepath)
6d5ae0de	64	{
d9deef0a JL	65	size_t pplen;
	66	size_t unclen;
	67	char *dev;
	68	char *pos;
6d5ae0de	69
d9deef0a JL	70	/* skip over any preceding delimiters */
	71	nodename += strspn(nodename, "\\");
	72	if (!*nodename)
7b91e266	73	return ERR_PTR(-EINVAL);
d9deef0a JL	74
	75	/* get length of UNC and set pos to last char */
	76	unclen = strlen(nodename);
	77	pos = nodename + unclen - 1;
	78
	79	/* trim off any trailing delimiters */
	80	while (*pos == '\\') {
	81	--pos;
	82	--unclen;
6d5ae0de IM	83	}
6d5ae0de IM	84
d9deef0a JL	85	/* allocate a buffer:
	86	* +2 for preceding "//"
	87	* +1 for delimiter between UNC and prepath
	88	* +1 for trailing NULL
	89	*/
	90	pplen = prepath ? strlen(prepath) : 0;
	91	dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
	92	if (!dev)
	93	return ERR_PTR(-ENOMEM);
	94
	95	pos = dev;
	96	/* add the initial "//" */
	97	*pos = '/';
	98	++pos;
	99	*pos = '/';
	100	++pos;
	101
	102	/* copy in the UNC portion from referral */
	103	memcpy(pos, nodename, unclen);
	104	pos += unclen;
	105
	106	/* copy the prefixpath remainder (if there is one) */
	107	if (pplen) {
	108	*pos = '/';
	109	++pos;
	110	memcpy(pos, prepath, pplen);
	111	pos += pplen;
6d5ae0de	112	}
6d5ae0de	113
d9deef0a JL	114	/* NULL terminator */
	115	*pos = '\0';
	116
	117	convert_delimiter(dev, '/');
	118	return dev;
6d5ae0de IM	119	}
	120
	121
	122	/**
c6c00919	123	* cifs_compose_mount_options - creates mount options for refferral
6d5ae0de	124	* @sb_mountdata: parent/root DFS mount options (template)
c6c00919	125	* @fullpath: full path in UNC format
2c55608f	126	* @ref: server's referral
d9345e0a	127	* @devname: optional pointer for saving device name
6d5ae0de IM	128	*
	129	* creates mount options for submount based on template options sb_mountdata
	130	* and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
	131	*
	132	* Returns: pointer to new mount options or ERR_PTR.
	133	* Caller is responcible for freeing retunrned value if it is not error.
	134	*/
c6c00919 SF	135	char cifs_compose_mount_options(const char sb_mountdata,
c6c00919 SF	136	const char *fullpath,
2c55608f	137	const struct dfs_info3_param *ref,
366781c1	138	char **devname)
6d5ae0de IM	139	{
6d5ae0de IM	140	int rc;
d9345e0a	141	char *name;
c6fbba05	142	char *mountdata = NULL;
d9deef0a	143	const char *prepath = NULL;
6d5ae0de IM	144	int md_len;
	145	char *tkn_e;
	146	char *srvIP = NULL;
	147	char sep = ',';
	148	int off, noff;
	149
	150	if (sb_mountdata == NULL)
	151	return ERR_PTR(-EINVAL);
	152
11e31647	153	if (strlen(fullpath) - ref->path_consumed) {
d9deef0a	154	prepath = fullpath + ref->path_consumed;
11e31647 SP	155	/* skip initial delimiter */
	156	if (prepath == '/' \|\| prepath == '\\')
	157	prepath++;
	158	}
d9deef0a	159
d9345e0a PA	160	name = cifs_build_devname(ref->node_name, prepath);
	161	if (IS_ERR(name)) {
	162	rc = PTR_ERR(name);
	163	name = NULL;
7b91e266 JL	164	goto compose_mount_options_err;
	165	}
	166
d9345e0a	167	rc = dns_resolve_server_name_to_ip(name, &srvIP);
67b7626a	168	if (rc < 0) {
f96637be	169	cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
d9345e0a	170	__func__, name, rc);
c6fbba05	171	goto compose_mount_options_err;
6d5ae0de	172	}
b8028983	173
d9deef0a JL	174	/*
	175	* In most cases, we'll be building a shorter string than the original,
	176	* but we do have to assume that the address in the ip= option may be
	177	* much longer than the original. Add the max length of an address
	178	* string to the length of the original string to allow for worst case.
2c55608f	179	*/
d9deef0a	180	md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
f34d69c3	181	mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
6d5ae0de	182	if (mountdata == NULL) {
c6fbba05 SF	183	rc = -ENOMEM;
c6fbba05 SF	184	goto compose_mount_options_err;
6d5ae0de IM	185	}
	186
	187	/* copy all options except of unc,ip,prefixpath */
	188	off = 0;
	189	if (strncmp(sb_mountdata, "sep=", 4) == 0) {
	190	sep = sb_mountdata[4];
	191	strncpy(mountdata, sb_mountdata, 5);
	192	off += 5;
	193	}
2c55608f IM	194
	195	do {
	196	tkn_e = strchr(sb_mountdata + off, sep);
	197	if (tkn_e == NULL)
	198	noff = strlen(sb_mountdata + off);
	199	else
	200	noff = tkn_e - (sb_mountdata + off) + 1;
	201
87e747cd	202	if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
6d5ae0de IM	203	off += noff;
	204	continue;
	205	}
87e747cd	206	if (strncasecmp(sb_mountdata + off, "ip=", 3) == 0) {
6d5ae0de IM	207	off += noff;
	208	continue;
	209	}
87e747cd	210	if (strncasecmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
6d5ae0de IM	211	off += noff;
	212	continue;
	213	}
2c55608f	214	strncat(mountdata, sb_mountdata + off, noff);
6d5ae0de	215	off += noff;
2c55608f IM	216	} while (tkn_e);
2c55608f IM	217	strcat(mountdata, sb_mountdata + off);
6d5ae0de IM	218	mountdata[md_len] = '\0';
	219
	220	/* copy new IP and ref share name */
2c55608f IM	221	if (mountdata[strlen(mountdata) - 1] != sep)
	222	strncat(mountdata, &sep, 1);
	223	strcat(mountdata, "ip=");
6d5ae0de	224	strcat(mountdata, srvIP);
6d5ae0de	225
d9345e0a PA	226	if (devname)
	227	*devname = name;
	228
f96637be JP	229	/cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);/
f96637be JP	230	/cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );/
6d5ae0de IM	231
	232	compose_mount_options_out:
	233	kfree(srvIP);
	234	return mountdata;
c6fbba05 SF	235
	236	compose_mount_options_err:
	237	kfree(mountdata);
	238	mountdata = ERR_PTR(rc);
d9345e0a	239	kfree(name);
c6fbba05	240	goto compose_mount_options_out;
6d5ae0de IM	241	}
6d5ae0de IM	242
f67909cf SF	243	/**
	244	* cifs_dfs_do_refmount - mounts specified path using provided refferal
	245	* @cifs_sb: parent/root superblock
	246	* @fullpath: full path in UNC format
	247	* @ref: server's referral
	248	*/
93faccbb EB	249	static struct vfsmount cifs_dfs_do_refmount(struct dentry mntpt,
93faccbb EB	250	struct cifs_sb_info *cifs_sb,
f67909cf	251	const char fullpath, const struct dfs_info3_param ref)
6d5ae0de	252	{
6d5ae0de IM	253	struct vfsmount *mnt;
6d5ae0de IM	254	char *mountdata;
4a367dc0 PA	255	char *devname;
	256
	257	/*
	258	* Always pass down the DFS full path to smb3_do_mount() so we
	259	* can use it later for failover.
	260	*/
	261	devname = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);
	262	if (!devname)
	263	return ERR_PTR(-ENOMEM);
	264
	265	convert_delimiter(devname, '/');
c6c00919	266
f67909cf	267	/* strip first '\' from fullpath */
c6c00919	268	mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
4a367dc0 PA	269	fullpath + 1, ref, NULL);
	270	if (IS_ERR(mountdata)) {
	271	kfree(devname);
6d5ae0de	272	return (struct vfsmount *)mountdata;
4a367dc0	273	}
6d5ae0de	274
93faccbb	275	mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
6d5ae0de IM	276	kfree(mountdata);
	277	kfree(devname);
	278	return mnt;
6d5ae0de IM	279	}
6d5ae0de IM	280
366781c1	281	static void dump_referral(const struct dfs_info3_param *ref)
6d5ae0de	282	{
f96637be JP	283	cifs_dbg(FYI, "DFS: ref path: %s\n", ref->path_name);
f96637be JP	284	cifs_dbg(FYI, "DFS: node path: %s\n", ref->node_name);
259594be	285	cifs_dbg(FYI, "DFS: fl: %d, srv_type: %d\n",
f96637be	286	ref->flags, ref->server_type);
259594be	287	cifs_dbg(FYI, "DFS: ref_flags: %d, path_consumed: %d\n",
f96637be	288	ref->ref_flag, ref->path_consumed);
6d5ae0de IM	289	}
6d5ae0de IM	290
01c64fea DH	291	/*
	292	* Create a vfsmount that we can automount
	293	*/
	294	static struct vfsmount cifs_dfs_do_automount(struct dentry mntpt)
6d5ae0de	295	{
1c780228	296	struct dfs_info3_param referral = {0};
6d5ae0de	297	struct cifs_sb_info *cifs_sb;
96daf2b0	298	struct cifs_ses *ses;
1c780228 PA	299	struct cifs_tcon *tcon;
1c780228 PA	300	char full_path, root_path;
6d5786a3	301	unsigned int xid;
1c780228	302	int len;
01c64fea DH	303	int rc;
01c64fea DH	304	struct vfsmount *mnt;
6d5ae0de	305
f96637be	306	cifs_dbg(FYI, "in %s\n", __func__);
01c64fea	307	BUG_ON(IS_ROOT(mntpt));
6d5ae0de	308
c6fbba05 SF	309	/*
	310	* The MSDFS spec states that paths in DFS referral requests and
	311	* responses must be prefixed by a single '\' character instead of
	312	* the double backslashes usually used in the UNC. This function
	313	* gives us the latter, so we must adjust the result.
	314	*/
01c64fea	315	mnt = ERR_PTR(-ENOMEM);
268a635d	316
8393072b AA	317	cifs_sb = CIFS_SB(mntpt->d_sb);
	318	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) {
	319	mnt = ERR_PTR(-EREMOTE);
	320	goto cdda_exit;
	321	}
	322
268a635d AA	323	/* always use tree name prefix */
268a635d AA	324	full_path = build_path_from_dentry_optional_prefix(mntpt, true);
01c64fea	325	if (full_path == NULL)
31c2659d	326	goto cdda_exit;
6d5ae0de	327
1c780228 PA	328	cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path);
	329
	330	if (!cifs_sb_master_tlink(cifs_sb)) {
	331	cifs_dbg(FYI, "%s: master tlink is NULL\n", __func__);
	332	goto free_full_path;
	333	}
	334
	335	tcon = cifs_sb_master_tcon(cifs_sb);
	336	if (!tcon) {
	337	cifs_dbg(FYI, "%s: master tcon is NULL\n", __func__);
01c64fea	338	goto free_full_path;
7ffec372	339	}
7ffec372	340
1c780228 PA	341	root_path = kstrdup(tcon->treeName, GFP_KERNEL);
	342	if (!root_path) {
	343	mnt = ERR_PTR(-ENOMEM);
	344	goto free_full_path;
	345	}
	346	cifs_dbg(FYI, "%s: root path: %s\n", __func__, root_path);
	347
	348	ses = tcon->ses;
6d5786a3	349	xid = get_xid();
6d5ae0de	350
1c780228 PA	351	/*
	352	* If DFS root has been expired, then unconditionally fetch it again to
	353	* refresh DFS referral cache.
	354	*/
	355	rc = dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
	356	root_path + 1, NULL, NULL);
	357	if (!rc) {
	358	rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,
	359	cifs_remap(cifs_sb), full_path + 1,
	360	&referral, NULL);
6d5ae0de IM	361	}
6d5ae0de IM	362
1c780228 PA	363	free_xid(xid);
	364
	365	if (rc) {
01c64fea	366	mnt = ERR_PTR(rc);
1c780228 PA	367	goto free_root_path;
1c780228 PA	368	}
6d5ae0de	369
1c780228 PA	370	dump_referral(&referral);
	371
	372	len = strlen(referral.node_name);
	373	if (len < 2) {
	374	cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
	375	__func__, referral.node_name);
	376	mnt = ERR_PTR(-EINVAL);
	377	goto free_dfs_ref;
	378	}
	379	/*
	380	* cifs_mount() will retry every available node server in case
	381	* of failures.
	382	*/
	383	mnt = cifs_dfs_do_refmount(mntpt, cifs_sb, full_path, &referral);
	384	cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n", __func__,
	385	referral.node_name, mnt);
	386
	387	free_dfs_ref:
	388	free_dfs_info_param(&referral);
	389	free_root_path:
	390	kfree(root_path);
01c64fea	391	free_full_path:
6d5ae0de	392	kfree(full_path);
31c2659d	393	cdda_exit:
f96637be	394	cifs_dbg(FYI, "leaving %s\n" , __func__);
01c64fea DH	395	return mnt;
	396	}
	397
	398	/*
	399	* Attempt to automount the referral
	400	*/
	401	struct vfsmount cifs_dfs_d_automount(struct path path)
	402	{
	403	struct vfsmount *newmnt;
01c64fea	404
f96637be	405	cifs_dbg(FYI, "in %s\n", __func__);
01c64fea DH	406
	407	newmnt = cifs_dfs_do_automount(path->dentry);
	408	if (IS_ERR(newmnt)) {
f96637be	409	cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
01c64fea DH	410	return newmnt;
	411	}
	412
ea5b778a DH	413	mntget(newmnt); /* prevent immediate expiration */
	414	mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
	415	schedule_delayed_work(&cifs_dfs_automount_task,
	416	cifs_dfs_mountpoint_expiry_timeout);
f96637be	417	cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
ea5b778a	418	return newmnt;
6d5ae0de IM	419	}
6d5ae0de IM	420
6e1d5dcc	421	const struct inode_operations cifs_dfs_referral_inode_operations = {
6d5ae0de	422	};