mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-05 10:04:12 +08:00
9d3dfea3d3
This patch modifies ovl_lookup() and friends to lookup metacopy dentries. It also allows for presence of metacopy dentries in lower layer. During lookup, check for presence of OVL_XATTR_METACOPY and if not present, set OVL_UPPERDATA bit in flags. We don't support metacopy feature with nfs_export. So in nfs_export code, we set OVL_UPPERDATA flag set unconditionally if upper inode exists. Do not follow metacopy origin if we find a metacopy only inode and metacopy feature is not enabled for that mount. Like redirect, this can have security implications where an attacker could hand craft upper and try to gain access to file on lower which it should not have to begin with. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
852 lines
22 KiB
C
852 lines
22 KiB
C
/*
|
|
* Overlayfs NFS export support.
|
|
*
|
|
* Amir Goldstein <amir73il@gmail.com>
|
|
*
|
|
* Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License version 2 as published by
|
|
* the Free Software Foundation.
|
|
*/
|
|
|
|
#include <linux/fs.h>
|
|
#include <linux/cred.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/xattr.h>
|
|
#include <linux/exportfs.h>
|
|
#include <linux/ratelimit.h>
|
|
#include "overlayfs.h"
|
|
|
|
static int ovl_encode_maybe_copy_up(struct dentry *dentry)
|
|
{
|
|
int err;
|
|
|
|
if (ovl_dentry_upper(dentry))
|
|
return 0;
|
|
|
|
err = ovl_want_write(dentry);
|
|
if (!err) {
|
|
err = ovl_copy_up(dentry);
|
|
ovl_drop_write(dentry);
|
|
}
|
|
|
|
if (err) {
|
|
pr_warn_ratelimited("overlayfs: failed to copy up on encode (%pd2, err=%i)\n",
|
|
dentry, err);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Before encoding a non-upper directory file handle from real layer N, we need
|
|
* to check if it will be possible to reconnect an overlay dentry from the real
|
|
* lower decoded dentry. This is done by following the overlay ancestry up to a
|
|
* "layer N connected" ancestor and verifying that all parents along the way are
|
|
* "layer N connectable". If an ancestor that is NOT "layer N connectable" is
|
|
* found, we need to copy up an ancestor, which is "layer N connectable", thus
|
|
* making that ancestor "layer N connected". For example:
|
|
*
|
|
* layer 1: /a
|
|
* layer 2: /a/b/c
|
|
*
|
|
* The overlay dentry /a is NOT "layer 2 connectable", because if dir /a is
|
|
* copied up and renamed, upper dir /a will be indexed by lower dir /a from
|
|
* layer 1. The dir /a from layer 2 will never be indexed, so the algorithm (*)
|
|
* in ovl_lookup_real_ancestor() will not be able to lookup a connected overlay
|
|
* dentry from the connected lower dentry /a/b/c.
|
|
*
|
|
* To avoid this problem on decode time, we need to copy up an ancestor of
|
|
* /a/b/c, which is "layer 2 connectable", on encode time. That ancestor is
|
|
* /a/b. After copy up (and index) of /a/b, it will become "layer 2 connected"
|
|
* and when the time comes to decode the file handle from lower dentry /a/b/c,
|
|
* ovl_lookup_real_ancestor() will find the indexed ancestor /a/b and decoding
|
|
* a connected overlay dentry will be accomplished.
|
|
*
|
|
* (*) the algorithm in ovl_lookup_real_ancestor() can be improved to lookup an
|
|
* entry /a in the lower layers above layer N and find the indexed dir /a from
|
|
* layer 1. If that improvement is made, then the check for "layer N connected"
|
|
* will need to verify there are no redirects in lower layers above N. In the
|
|
* example above, /a will be "layer 2 connectable". However, if layer 2 dir /a
|
|
* is a target of a layer 1 redirect, then /a will NOT be "layer 2 connectable":
|
|
*
|
|
* layer 1: /A (redirect = /a)
|
|
* layer 2: /a/b/c
|
|
*/
|
|
|
|
/* Return the lowest layer for encoding a connectable file handle */
|
|
static int ovl_connectable_layer(struct dentry *dentry)
|
|
{
|
|
struct ovl_entry *oe = OVL_E(dentry);
|
|
|
|
/* We can get overlay root from root of any layer */
|
|
if (dentry == dentry->d_sb->s_root)
|
|
return oe->numlower;
|
|
|
|
/*
|
|
* If it's an unindexed merge dir, then it's not connectable with any
|
|
* lower layer
|
|
*/
|
|
if (ovl_dentry_upper(dentry) &&
|
|
!ovl_test_flag(OVL_INDEX, d_inode(dentry)))
|
|
return 0;
|
|
|
|
/* We can get upper/overlay path from indexed/lower dentry */
|
|
return oe->lowerstack[0].layer->idx;
|
|
}
|
|
|
|
/*
|
|
* @dentry is "connected" if all ancestors up to root or a "connected" ancestor
|
|
* have the same uppermost lower layer as the origin's layer. We may need to
|
|
* copy up a "connectable" ancestor to make it "connected". A "connected" dentry
|
|
* cannot become non "connected", so cache positive result in dentry flags.
|
|
*
|
|
* Return the connected origin layer or < 0 on error.
|
|
*/
|
|
static int ovl_connect_layer(struct dentry *dentry)
|
|
{
|
|
struct dentry *next, *parent = NULL;
|
|
int origin_layer;
|
|
int err = 0;
|
|
|
|
if (WARN_ON(dentry == dentry->d_sb->s_root) ||
|
|
WARN_ON(!ovl_dentry_lower(dentry)))
|
|
return -EIO;
|
|
|
|
origin_layer = OVL_E(dentry)->lowerstack[0].layer->idx;
|
|
if (ovl_dentry_test_flag(OVL_E_CONNECTED, dentry))
|
|
return origin_layer;
|
|
|
|
/* Find the topmost origin layer connectable ancestor of @dentry */
|
|
next = dget(dentry);
|
|
for (;;) {
|
|
parent = dget_parent(next);
|
|
if (WARN_ON(parent == next)) {
|
|
err = -EIO;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If @parent is not origin layer connectable, then copy up
|
|
* @next which is origin layer connectable and we are done.
|
|
*/
|
|
if (ovl_connectable_layer(parent) < origin_layer) {
|
|
err = ovl_encode_maybe_copy_up(next);
|
|
break;
|
|
}
|
|
|
|
/* If @parent is connected or indexed we are done */
|
|
if (ovl_dentry_test_flag(OVL_E_CONNECTED, parent) ||
|
|
ovl_test_flag(OVL_INDEX, d_inode(parent)))
|
|
break;
|
|
|
|
dput(next);
|
|
next = parent;
|
|
}
|
|
|
|
dput(parent);
|
|
dput(next);
|
|
|
|
if (!err)
|
|
ovl_dentry_set_flag(OVL_E_CONNECTED, dentry);
|
|
|
|
return err ?: origin_layer;
|
|
}
|
|
|
|
/*
|
|
* We only need to encode origin if there is a chance that the same object was
|
|
* encoded pre copy up and then we need to stay consistent with the same
|
|
* encoding also after copy up. If non-pure upper is not indexed, then it was
|
|
* copied up before NFS export was enabled. In that case we don't need to worry
|
|
* about staying consistent with pre copy up encoding and we encode an upper
|
|
* file handle. Overlay root dentry is a private case of non-indexed upper.
|
|
*
|
|
* The following table summarizes the different file handle encodings used for
|
|
* different overlay object types:
|
|
*
|
|
* Object type | Encoding
|
|
* --------------------------------
|
|
* Pure upper | U
|
|
* Non-indexed upper | U
|
|
* Indexed upper | L (*)
|
|
* Non-upper | L (*)
|
|
*
|
|
* U = upper file handle
|
|
* L = lower file handle
|
|
*
|
|
* (*) Connecting an overlay dir from real lower dentry is not always
|
|
* possible when there are redirects in lower layers and non-indexed merge dirs.
|
|
* To mitigate those case, we may copy up the lower dir ancestor before encode
|
|
* a lower dir file handle.
|
|
*
|
|
* Return 0 for upper file handle, > 0 for lower file handle or < 0 on error.
|
|
*/
|
|
static int ovl_check_encode_origin(struct dentry *dentry)
|
|
{
|
|
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
|
|
|
/* Upper file handle for pure upper */
|
|
if (!ovl_dentry_lower(dentry))
|
|
return 0;
|
|
|
|
/*
|
|
* Upper file handle for non-indexed upper.
|
|
*
|
|
* Root is never indexed, so if there's an upper layer, encode upper for
|
|
* root.
|
|
*/
|
|
if (ovl_dentry_upper(dentry) &&
|
|
!ovl_test_flag(OVL_INDEX, d_inode(dentry)))
|
|
return 0;
|
|
|
|
/*
|
|
* Decoding a merge dir, whose origin's ancestor is under a redirected
|
|
* lower dir or under a non-indexed upper is not always possible.
|
|
* ovl_connect_layer() will try to make origin's layer "connected" by
|
|
* copying up a "connectable" ancestor.
|
|
*/
|
|
if (d_is_dir(dentry) && ofs->upper_mnt)
|
|
return ovl_connect_layer(dentry);
|
|
|
|
/* Lower file handle for indexed and non-upper dir/non-dir */
|
|
return 1;
|
|
}
|
|
|
|
static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
|
|
{
|
|
struct ovl_fh *fh = NULL;
|
|
int err, enc_lower;
|
|
|
|
/*
|
|
* Check if we should encode a lower or upper file handle and maybe
|
|
* copy up an ancestor to make lower file handle connectable.
|
|
*/
|
|
err = enc_lower = ovl_check_encode_origin(dentry);
|
|
if (enc_lower < 0)
|
|
goto fail;
|
|
|
|
/* Encode an upper or lower file handle */
|
|
fh = ovl_encode_real_fh(enc_lower ? ovl_dentry_lower(dentry) :
|
|
ovl_dentry_upper(dentry), !enc_lower);
|
|
err = PTR_ERR(fh);
|
|
if (IS_ERR(fh))
|
|
goto fail;
|
|
|
|
err = -EOVERFLOW;
|
|
if (fh->len > buflen)
|
|
goto fail;
|
|
|
|
memcpy(buf, (char *)fh, fh->len);
|
|
err = fh->len;
|
|
|
|
out:
|
|
kfree(fh);
|
|
return err;
|
|
|
|
fail:
|
|
pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n",
|
|
dentry, err, buflen, fh ? (int)fh->len : 0,
|
|
fh ? fh->type : 0);
|
|
goto out;
|
|
}
|
|
|
|
static int ovl_dentry_to_fh(struct dentry *dentry, u32 *fid, int *max_len)
|
|
{
|
|
int res, len = *max_len << 2;
|
|
|
|
res = ovl_d_to_fh(dentry, (char *)fid, len);
|
|
if (res <= 0)
|
|
return FILEID_INVALID;
|
|
|
|
len = res;
|
|
|
|
/* Round up to dwords */
|
|
*max_len = (len + 3) >> 2;
|
|
return OVL_FILEID;
|
|
}
|
|
|
|
static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
|
|
struct inode *parent)
|
|
{
|
|
struct dentry *dentry;
|
|
int type;
|
|
|
|
/* TODO: encode connectable file handles */
|
|
if (parent)
|
|
return FILEID_INVALID;
|
|
|
|
dentry = d_find_any_alias(inode);
|
|
if (WARN_ON(!dentry))
|
|
return FILEID_INVALID;
|
|
|
|
type = ovl_dentry_to_fh(dentry, fid, max_len);
|
|
|
|
dput(dentry);
|
|
return type;
|
|
}
|
|
|
|
/*
|
|
* Find or instantiate an overlay dentry from real dentries and index.
|
|
*/
|
|
static struct dentry *ovl_obtain_alias(struct super_block *sb,
|
|
struct dentry *upper_alias,
|
|
struct ovl_path *lowerpath,
|
|
struct dentry *index)
|
|
{
|
|
struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;
|
|
struct dentry *upper = upper_alias ?: index;
|
|
struct dentry *dentry;
|
|
struct inode *inode;
|
|
struct ovl_entry *oe;
|
|
struct ovl_inode_params oip = {
|
|
.lowerpath = lowerpath,
|
|
.index = index,
|
|
.numlower = !!lower
|
|
};
|
|
|
|
/* We get overlay directory dentries with ovl_lookup_real() */
|
|
if (d_is_dir(upper ?: lower))
|
|
return ERR_PTR(-EIO);
|
|
|
|
oip.upperdentry = dget(upper);
|
|
inode = ovl_get_inode(sb, &oip);
|
|
if (IS_ERR(inode)) {
|
|
dput(upper);
|
|
return ERR_CAST(inode);
|
|
}
|
|
|
|
if (upper)
|
|
ovl_set_flag(OVL_UPPERDATA, inode);
|
|
|
|
dentry = d_find_any_alias(inode);
|
|
if (!dentry) {
|
|
dentry = d_alloc_anon(inode->i_sb);
|
|
if (!dentry)
|
|
goto nomem;
|
|
oe = ovl_alloc_entry(lower ? 1 : 0);
|
|
if (!oe)
|
|
goto nomem;
|
|
|
|
if (lower) {
|
|
oe->lowerstack->dentry = dget(lower);
|
|
oe->lowerstack->layer = lowerpath->layer;
|
|
}
|
|
dentry->d_fsdata = oe;
|
|
if (upper_alias)
|
|
ovl_dentry_set_upper_alias(dentry);
|
|
}
|
|
|
|
return d_instantiate_anon(dentry, inode);
|
|
|
|
nomem:
|
|
iput(inode);
|
|
dput(dentry);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
/* Get the upper or lower dentry in stach whose on layer @idx */
|
|
static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx)
|
|
{
|
|
struct ovl_entry *oe = dentry->d_fsdata;
|
|
int i;
|
|
|
|
if (!idx)
|
|
return ovl_dentry_upper(dentry);
|
|
|
|
for (i = 0; i < oe->numlower; i++) {
|
|
if (oe->lowerstack[i].layer->idx == idx)
|
|
return oe->lowerstack[i].dentry;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Lookup a child overlay dentry to get a connected overlay dentry whose real
|
|
* dentry is @real. If @real is on upper layer, we lookup a child overlay
|
|
* dentry with the same name as the real dentry. Otherwise, we need to consult
|
|
* index for lookup.
|
|
*/
|
|
static struct dentry *ovl_lookup_real_one(struct dentry *connected,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer)
|
|
{
|
|
struct inode *dir = d_inode(connected);
|
|
struct dentry *this, *parent = NULL;
|
|
struct name_snapshot name;
|
|
int err;
|
|
|
|
/*
|
|
* Lookup child overlay dentry by real name. The dir mutex protects us
|
|
* from racing with overlay rename. If the overlay dentry that is above
|
|
* real has already been moved to a parent that is not under the
|
|
* connected overlay dir, we return -ECHILD and restart the lookup of
|
|
* connected real path from the top.
|
|
*/
|
|
inode_lock_nested(dir, I_MUTEX_PARENT);
|
|
err = -ECHILD;
|
|
parent = dget_parent(real);
|
|
if (ovl_dentry_real_at(connected, layer->idx) != parent)
|
|
goto fail;
|
|
|
|
/*
|
|
* We also need to take a snapshot of real dentry name to protect us
|
|
* from racing with underlying layer rename. In this case, we don't
|
|
* care about returning ESTALE, only from dereferencing a free name
|
|
* pointer because we hold no lock on the real dentry.
|
|
*/
|
|
take_dentry_name_snapshot(&name, real);
|
|
this = lookup_one_len(name.name, connected, strlen(name.name));
|
|
err = PTR_ERR(this);
|
|
if (IS_ERR(this)) {
|
|
goto fail;
|
|
} else if (!this || !this->d_inode) {
|
|
dput(this);
|
|
err = -ENOENT;
|
|
goto fail;
|
|
} else if (ovl_dentry_real_at(this, layer->idx) != real) {
|
|
dput(this);
|
|
err = -ESTALE;
|
|
goto fail;
|
|
}
|
|
|
|
out:
|
|
release_dentry_name_snapshot(&name);
|
|
dput(parent);
|
|
inode_unlock(dir);
|
|
return this;
|
|
|
|
fail:
|
|
pr_warn_ratelimited("overlayfs: failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
|
|
real, layer->idx, connected, err);
|
|
this = ERR_PTR(err);
|
|
goto out;
|
|
}
|
|
|
|
static struct dentry *ovl_lookup_real(struct super_block *sb,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer);
|
|
|
|
/*
|
|
* Lookup an indexed or hashed overlay dentry by real inode.
|
|
*/
|
|
static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
|
|
struct dentry *index = NULL;
|
|
struct dentry *this = NULL;
|
|
struct inode *inode;
|
|
|
|
/*
|
|
* Decoding upper dir from index is expensive, so first try to lookup
|
|
* overlay dentry in inode/dcache.
|
|
*/
|
|
inode = ovl_lookup_inode(sb, real, !layer->idx);
|
|
if (IS_ERR(inode))
|
|
return ERR_CAST(inode);
|
|
if (inode) {
|
|
this = d_find_any_alias(inode);
|
|
iput(inode);
|
|
}
|
|
|
|
/*
|
|
* For decoded lower dir file handle, lookup index by origin to check
|
|
* if lower dir was copied up and and/or removed.
|
|
*/
|
|
if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) {
|
|
index = ovl_lookup_index(ofs, NULL, real, false);
|
|
if (IS_ERR(index))
|
|
return index;
|
|
}
|
|
|
|
/* Get connected upper overlay dir from index */
|
|
if (index) {
|
|
struct dentry *upper = ovl_index_upper(ofs, index);
|
|
|
|
dput(index);
|
|
if (IS_ERR_OR_NULL(upper))
|
|
return upper;
|
|
|
|
/*
|
|
* ovl_lookup_real() in lower layer may call recursively once to
|
|
* ovl_lookup_real() in upper layer. The first level call walks
|
|
* back lower parents to the topmost indexed parent. The second
|
|
* recursive call walks back from indexed upper to the topmost
|
|
* connected/hashed upper parent (or up to root).
|
|
*/
|
|
this = ovl_lookup_real(sb, upper, &upper_layer);
|
|
dput(upper);
|
|
}
|
|
|
|
if (IS_ERR_OR_NULL(this))
|
|
return this;
|
|
|
|
if (WARN_ON(ovl_dentry_real_at(this, layer->idx) != real)) {
|
|
dput(this);
|
|
this = ERR_PTR(-EIO);
|
|
}
|
|
|
|
return this;
|
|
}
|
|
|
|
/*
|
|
* Lookup an indexed or hashed overlay dentry, whose real dentry is an
|
|
* ancestor of @real.
|
|
*/
|
|
static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer)
|
|
{
|
|
struct dentry *next, *parent = NULL;
|
|
struct dentry *ancestor = ERR_PTR(-EIO);
|
|
|
|
if (real == layer->mnt->mnt_root)
|
|
return dget(sb->s_root);
|
|
|
|
/* Find the topmost indexed or hashed ancestor */
|
|
next = dget(real);
|
|
for (;;) {
|
|
parent = dget_parent(next);
|
|
|
|
/*
|
|
* Lookup a matching overlay dentry in inode/dentry
|
|
* cache or in index by real inode.
|
|
*/
|
|
ancestor = ovl_lookup_real_inode(sb, next, layer);
|
|
if (ancestor)
|
|
break;
|
|
|
|
if (parent == layer->mnt->mnt_root) {
|
|
ancestor = dget(sb->s_root);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If @real has been moved out of the layer root directory,
|
|
* we will eventully hit the real fs root. This cannot happen
|
|
* by legit overlay rename, so we return error in that case.
|
|
*/
|
|
if (parent == next) {
|
|
ancestor = ERR_PTR(-EXDEV);
|
|
break;
|
|
}
|
|
|
|
dput(next);
|
|
next = parent;
|
|
}
|
|
|
|
dput(parent);
|
|
dput(next);
|
|
|
|
return ancestor;
|
|
}
|
|
|
|
/*
|
|
* Lookup a connected overlay dentry whose real dentry is @real.
|
|
* If @real is on upper layer, we lookup a child overlay dentry with the same
|
|
* path the real dentry. Otherwise, we need to consult index for lookup.
|
|
*/
|
|
static struct dentry *ovl_lookup_real(struct super_block *sb,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer)
|
|
{
|
|
struct dentry *connected;
|
|
int err = 0;
|
|
|
|
connected = ovl_lookup_real_ancestor(sb, real, layer);
|
|
if (IS_ERR(connected))
|
|
return connected;
|
|
|
|
while (!err) {
|
|
struct dentry *next, *this;
|
|
struct dentry *parent = NULL;
|
|
struct dentry *real_connected = ovl_dentry_real_at(connected,
|
|
layer->idx);
|
|
|
|
if (real_connected == real)
|
|
break;
|
|
|
|
/* Find the topmost dentry not yet connected */
|
|
next = dget(real);
|
|
for (;;) {
|
|
parent = dget_parent(next);
|
|
|
|
if (parent == real_connected)
|
|
break;
|
|
|
|
/*
|
|
* If real has been moved out of 'real_connected',
|
|
* we will not find 'real_connected' and hit the layer
|
|
* root. In that case, we need to restart connecting.
|
|
* This game can go on forever in the worst case. We
|
|
* may want to consider taking s_vfs_rename_mutex if
|
|
* this happens more than once.
|
|
*/
|
|
if (parent == layer->mnt->mnt_root) {
|
|
dput(connected);
|
|
connected = dget(sb->s_root);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If real file has been moved out of the layer root
|
|
* directory, we will eventully hit the real fs root.
|
|
* This cannot happen by legit overlay rename, so we
|
|
* return error in that case.
|
|
*/
|
|
if (parent == next) {
|
|
err = -EXDEV;
|
|
break;
|
|
}
|
|
|
|
dput(next);
|
|
next = parent;
|
|
}
|
|
|
|
if (!err) {
|
|
this = ovl_lookup_real_one(connected, next, layer);
|
|
if (IS_ERR(this))
|
|
err = PTR_ERR(this);
|
|
|
|
/*
|
|
* Lookup of child in overlay can fail when racing with
|
|
* overlay rename of child away from 'connected' parent.
|
|
* In this case, we need to restart the lookup from the
|
|
* top, because we cannot trust that 'real_connected' is
|
|
* still an ancestor of 'real'. There is a good chance
|
|
* that the renamed overlay ancestor is now in cache, so
|
|
* ovl_lookup_real_ancestor() will find it and we can
|
|
* continue to connect exactly from where lookup failed.
|
|
*/
|
|
if (err == -ECHILD) {
|
|
this = ovl_lookup_real_ancestor(sb, real,
|
|
layer);
|
|
err = PTR_ERR_OR_ZERO(this);
|
|
}
|
|
if (!err) {
|
|
dput(connected);
|
|
connected = this;
|
|
}
|
|
}
|
|
|
|
dput(parent);
|
|
dput(next);
|
|
}
|
|
|
|
if (err)
|
|
goto fail;
|
|
|
|
return connected;
|
|
|
|
fail:
|
|
pr_warn_ratelimited("overlayfs: failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
|
|
real, layer->idx, connected, err);
|
|
dput(connected);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
/*
|
|
* Get an overlay dentry from upper/lower real dentries and index.
|
|
*/
|
|
static struct dentry *ovl_get_dentry(struct super_block *sb,
|
|
struct dentry *upper,
|
|
struct ovl_path *lowerpath,
|
|
struct dentry *index)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
|
|
struct ovl_layer *layer = upper ? &upper_layer : lowerpath->layer;
|
|
struct dentry *real = upper ?: (index ?: lowerpath->dentry);
|
|
|
|
/*
|
|
* Obtain a disconnected overlay dentry from a non-dir real dentry
|
|
* and index.
|
|
*/
|
|
if (!d_is_dir(real))
|
|
return ovl_obtain_alias(sb, upper, lowerpath, index);
|
|
|
|
/* Removed empty directory? */
|
|
if ((real->d_flags & DCACHE_DISCONNECTED) || d_unhashed(real))
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
/*
|
|
* If real dentry is connected and hashed, get a connected overlay
|
|
* dentry whose real dentry is @real.
|
|
*/
|
|
return ovl_lookup_real(sb, real, layer);
|
|
}
|
|
|
|
static struct dentry *ovl_upper_fh_to_d(struct super_block *sb,
|
|
struct ovl_fh *fh)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
struct dentry *dentry;
|
|
struct dentry *upper;
|
|
|
|
if (!ofs->upper_mnt)
|
|
return ERR_PTR(-EACCES);
|
|
|
|
upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
|
|
if (IS_ERR_OR_NULL(upper))
|
|
return upper;
|
|
|
|
dentry = ovl_get_dentry(sb, upper, NULL, NULL);
|
|
dput(upper);
|
|
|
|
return dentry;
|
|
}
|
|
|
|
static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
|
|
struct ovl_fh *fh)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
struct ovl_path origin = { };
|
|
struct ovl_path *stack = &origin;
|
|
struct dentry *dentry = NULL;
|
|
struct dentry *index = NULL;
|
|
struct inode *inode;
|
|
int err;
|
|
|
|
/* First lookup overlay inode in inode cache by origin fh */
|
|
err = ovl_check_origin_fh(ofs, fh, false, NULL, &stack);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
if (!d_is_dir(origin.dentry) ||
|
|
!(origin.dentry->d_flags & DCACHE_DISCONNECTED)) {
|
|
inode = ovl_lookup_inode(sb, origin.dentry, false);
|
|
err = PTR_ERR(inode);
|
|
if (IS_ERR(inode))
|
|
goto out_err;
|
|
if (inode) {
|
|
dentry = d_find_any_alias(inode);
|
|
iput(inode);
|
|
if (dentry)
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/* Then lookup indexed upper/whiteout by origin fh */
|
|
if (ofs->indexdir) {
|
|
index = ovl_get_index_fh(ofs, fh);
|
|
err = PTR_ERR(index);
|
|
if (IS_ERR(index)) {
|
|
index = NULL;
|
|
goto out_err;
|
|
}
|
|
}
|
|
|
|
/* Then try to get a connected upper dir by index */
|
|
if (index && d_is_dir(index)) {
|
|
struct dentry *upper = ovl_index_upper(ofs, index);
|
|
|
|
err = PTR_ERR(upper);
|
|
if (IS_ERR_OR_NULL(upper))
|
|
goto out_err;
|
|
|
|
dentry = ovl_get_dentry(sb, upper, NULL, NULL);
|
|
dput(upper);
|
|
goto out;
|
|
}
|
|
|
|
/* Otherwise, get a connected non-upper dir or disconnected non-dir */
|
|
if (d_is_dir(origin.dentry) &&
|
|
(origin.dentry->d_flags & DCACHE_DISCONNECTED)) {
|
|
dput(origin.dentry);
|
|
origin.dentry = NULL;
|
|
err = ovl_check_origin_fh(ofs, fh, true, NULL, &stack);
|
|
if (err)
|
|
goto out_err;
|
|
}
|
|
if (index) {
|
|
err = ovl_verify_origin(index, origin.dentry, false);
|
|
if (err)
|
|
goto out_err;
|
|
}
|
|
|
|
dentry = ovl_get_dentry(sb, NULL, &origin, index);
|
|
|
|
out:
|
|
dput(origin.dentry);
|
|
dput(index);
|
|
return dentry;
|
|
|
|
out_err:
|
|
dentry = ERR_PTR(err);
|
|
goto out;
|
|
}
|
|
|
|
static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,
|
|
int fh_len, int fh_type)
|
|
{
|
|
struct dentry *dentry = NULL;
|
|
struct ovl_fh *fh = (struct ovl_fh *) fid;
|
|
int len = fh_len << 2;
|
|
unsigned int flags = 0;
|
|
int err;
|
|
|
|
err = -EINVAL;
|
|
if (fh_type != OVL_FILEID)
|
|
goto out_err;
|
|
|
|
err = ovl_check_fh_len(fh, len);
|
|
if (err)
|
|
goto out_err;
|
|
|
|
flags = fh->flags;
|
|
dentry = (flags & OVL_FH_FLAG_PATH_UPPER) ?
|
|
ovl_upper_fh_to_d(sb, fh) :
|
|
ovl_lower_fh_to_d(sb, fh);
|
|
err = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry) && err != -ESTALE)
|
|
goto out_err;
|
|
|
|
return dentry;
|
|
|
|
out_err:
|
|
pr_warn_ratelimited("overlayfs: failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n",
|
|
len, fh_type, flags, err);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid,
|
|
int fh_len, int fh_type)
|
|
{
|
|
pr_warn_ratelimited("overlayfs: connectable file handles not supported; use 'no_subtree_check' exportfs option.\n");
|
|
return ERR_PTR(-EACCES);
|
|
}
|
|
|
|
static int ovl_get_name(struct dentry *parent, char *name,
|
|
struct dentry *child)
|
|
{
|
|
/*
|
|
* ovl_fh_to_dentry() returns connected dir overlay dentries and
|
|
* ovl_fh_to_parent() is not implemented, so we should not get here.
|
|
*/
|
|
WARN_ON_ONCE(1);
|
|
return -EIO;
|
|
}
|
|
|
|
static struct dentry *ovl_get_parent(struct dentry *dentry)
|
|
{
|
|
/*
|
|
* ovl_fh_to_dentry() returns connected dir overlay dentries, so we
|
|
* should not get here.
|
|
*/
|
|
WARN_ON_ONCE(1);
|
|
return ERR_PTR(-EIO);
|
|
}
|
|
|
|
const struct export_operations ovl_export_operations = {
|
|
.encode_fh = ovl_encode_fh,
|
|
.fh_to_dentry = ovl_fh_to_dentry,
|
|
.fh_to_parent = ovl_fh_to_parent,
|
|
.get_name = ovl_get_name,
|
|
.get_parent = ovl_get_parent,
|
|
};
|