linux/fs/cifs/cifs_dfs_ref.c
Jeff Layton b802898334 cifs: demote DFS referral lookup errors to cFYI
cifs: demote DFS referral lookup errors to cFYI

Now that we call into this routine on every mount, anyone who doesn't
have the upcall configured will get multiple printks about failed lookups.

Reported-and-Tested-by: Martijn Uffing <mp3project@sarijopen.student.utwente.nl>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2011-08-03 03:19:28 +00:00

372 lines
9.5 KiB
C

/*
* 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 "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_get_share_name - extracts share name from UNC
* @node_name: pointer to UNC string
*
* Extracts sharename form full UNC.
* i.e. strips from UNC trailing path that is not part of share
* name and fixup missing '\' in the beginning of DFS node refferal
* if necessary.
* Returns pointer to share name on success or ERR_PTR on error.
* Caller is responsible for freeing returned string.
*/
static char *cifs_get_share_name(const char *node_name)
{
int len;
char *UNC;
char *pSep;
len = strlen(node_name);
UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
GFP_KERNEL);
if (!UNC)
return ERR_PTR(-ENOMEM);
/* get share name and server name */
if (node_name[1] != '\\') {
UNC[0] = '\\';
strncpy(UNC+1, node_name, len);
len++;
UNC[len] = 0;
} else {
strncpy(UNC, node_name, len);
UNC[len] = 0;
}
/* find server name end */
pSep = memchr(UNC+2, '\\', len-2);
if (!pSep) {
cERROR(1, "%s: no server name end in node name: %s",
__func__, node_name);
kfree(UNC);
return ERR_PTR(-EINVAL);
}
/* find sharename end */
pSep++;
pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
if (pSep) {
/* trim path up to sharename end
* now we have share name in UNC */
*pSep = 0;
}
return UNC;
}
/**
* 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;
int md_len;
char *tkn_e;
char *srvIP = NULL;
char sep = ',';
int off, noff;
if (sb_mountdata == NULL)
return ERR_PTR(-EINVAL);
*devname = cifs_get_share_name(ref->node_name);
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) {
cFYI(1, "%s: Failed to resolve server part of %s to IP: %d",
__func__, *devname, rc);
goto compose_mount_options_err;
}
/* md_len = strlen(...) + 12 for 'sep+prefixpath='
* assuming that we have 'unc=' and 'ip=' in
* the original sb_mountdata
*/
md_len = strlen(sb_mountdata) + rc + strlen(ref->node_name) + 12;
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 (strnicmp(sb_mountdata + off, "unc=", 4) == 0) {
off += noff;
continue;
}
if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) {
off += noff;
continue;
}
if (strnicmp(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);
strncat(mountdata, &sep, 1);
strcat(mountdata, "unc=");
strcat(mountdata, *devname);
/* find & copy prefixpath */
tkn_e = strchr(ref->node_name + 2, '\\');
if (tkn_e == NULL) {
/* invalid unc, missing share name*/
rc = -EINVAL;
goto compose_mount_options_err;
}
tkn_e = strchr(tkn_e + 1, '\\');
if (tkn_e || (strlen(fullpath) - ref->path_consumed)) {
strncat(mountdata, &sep, 1);
strcat(mountdata, "prefixpath=");
if (tkn_e)
strcat(mountdata, tkn_e + 1);
strcat(mountdata, fullpath + ref->path_consumed);
}
/*cFYI(1, "%s: parent mountdata: %s", __func__,sb_mountdata);*/
/*cFYI(1, "%s: submount mountdata: %s", __func__, mountdata );*/
compose_mount_options_out:
kfree(srvIP);
return mountdata;
compose_mount_options_err:
kfree(mountdata);
mountdata = ERR_PTR(rc);
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)
{
cFYI(1, "DFS: ref path: %s", ref->path_name);
cFYI(1, "DFS: node path: %s", ref->node_name);
cFYI(1, "DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type);
cFYI(1, "DFS: ref_flags: %hd, path_consumed: %hd", 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;
int xid, i;
int rc;
struct vfsmount *mnt;
struct tcon_link *tlink;
cFYI(1, "in %s", __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 = GetXid();
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);
FreeXid(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) {
cERROR(1, "%s: Net Address path too short: %s",
__func__, referrals[i].node_name);
mnt = ERR_PTR(-EINVAL);
break;
}
mnt = cifs_dfs_do_refmount(cifs_sb,
full_path, referrals + i);
cFYI(1, "%s: cifs_dfs_do_refmount:%s , mnt:%p", __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:
cFYI(1, "leaving %s" , __func__);
return mnt;
}
/*
* Attempt to automount the referral
*/
struct vfsmount *cifs_dfs_d_automount(struct path *path)
{
struct vfsmount *newmnt;
cFYI(1, "in %s", __func__);
newmnt = cifs_dfs_do_automount(path->dentry);
if (IS_ERR(newmnt)) {
cFYI(1, "leaving %s [automount failed]" , __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);
cFYI(1, "leaving %s [ok]" , __func__);
return newmnt;
}
const struct inode_operations cifs_dfs_referral_inode_operations = {
};