util.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2011 Novell Inc.
* Copyright (C) 2016 Red Hat, Inc.
*/
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/xattr.h>
#include <linux/exportfs.h>
#include <linux/fileattr.h>
#include <linux/uuid.h>
#include <linux/namei.h>
#include <linux/ratelimit.h>
#include "overlayfs.h"
int ovl_want_write(struct dentry *dentry)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
return mnt_want_write(ovl_upper_mnt(ofs));
}
void ovl_drop_write(struct dentry *dentry)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
mnt_drop_write(ovl_upper_mnt(ofs));
}
struct dentry *ovl_workdir(struct dentry *dentry)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
return ofs->workdir;
}
const struct cred *ovl_override_creds(struct super_block *sb)
{
struct ovl_fs *ofs = sb->s_fs_info;
return override_creds(ofs->creator_cred);
}
/*
* Check if underlying fs supports file handles and try to determine encoding
* type, in order to deduce maximum inode number used by fs.
*
* Return 0 if file handles are not supported.
* Return 1 (FILEID_INO32_GEN) if fs uses the default 32bit inode encoding.
* Return -1 if fs uses a non default encoding with unknown inode size.
*/
int ovl_can_decode_fh(struct super_block *sb)
{
if (!capable(CAP_DAC_READ_SEARCH))
return 0;
if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry)
return 0;
return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
}
struct dentry *ovl_indexdir(struct super_block *sb)
{
struct ovl_fs *ofs = sb->s_fs_info;
return ofs->indexdir;
}
/* Index all files on copy up. For now only enabled for NFS export */
bool ovl_index_all(struct super_block *sb)
{
struct ovl_fs *ofs = sb->s_fs_info;
return ofs->config.nfs_export && ofs->config.index;
}
/* Verify lower origin on lookup. For now only enabled for NFS export */
bool ovl_verify_lower(struct super_block *sb)
{
struct ovl_fs *ofs = sb->s_fs_info;
return ofs->config.nfs_export && ofs->config.index;
}
struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
{
size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
if (oe)
oe->numlower = numlower;
return oe;
}
bool ovl_dentry_remote(struct dentry *dentry)
{
return dentry->d_flags &
(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
}
void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
unsigned int mask)
{
struct ovl_entry *oe = OVL_E(dentry);
unsigned int i, flags = 0;
if (upperdentry)
flags |= upperdentry->d_flags;
for (i = 0; i < oe->numlower; i++)
flags |= oe->lowerstack[i].dentry->d_flags;
spin_lock(&dentry->d_lock);
dentry->d_flags &= ~mask;
dentry->d_flags |= flags & mask;
spin_unlock(&dentry->d_lock);
}
bool ovl_dentry_weird(struct dentry *dentry)
{
return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
DCACHE_MANAGE_TRANSIT |
DCACHE_OP_HASH |
DCACHE_OP_COMPARE);
}
enum ovl_path_type ovl_path_type(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
enum ovl_path_type type = 0;
if (ovl_dentry_upper(dentry)) {
type = __OVL_PATH_UPPER;
/*
* Non-dir dentry can hold lower dentry of its copy up origin.
*/
if (oe->numlower) {
if (ovl_test_flag(OVL_CONST_INO, d_inode(dentry)))
type |= __OVL_PATH_ORIGIN;
if (d_is_dir(dentry) ||
!ovl_has_upperdata(d_inode(dentry)))
type |= __OVL_PATH_MERGE;
}
} else {
if (oe->numlower > 1)
type |= __OVL_PATH_MERGE;
}
return type;
}
void ovl_path_upper(struct dentry *dentry, struct path *path)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
path->mnt = ovl_upper_mnt(ofs);
path->dentry = ovl_dentry_upper(dentry);
}
void ovl_path_lower(struct dentry *dentry, struct path *path)
{
struct ovl_entry *oe = dentry->d_fsdata;
if (oe->numlower) {
path->mnt = oe->lowerstack[0].layer->mnt;
path->dentry = oe->lowerstack[0].dentry;
} else {
*path = (struct path) { };
}
}
void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
{
struct ovl_entry *oe = dentry->d_fsdata;
if (oe->numlower) {
path->mnt = oe->lowerstack[oe->numlower - 1].layer->mnt;
path->dentry = oe->lowerstack[oe->numlower - 1].dentry;
} else {
*path = (struct path) { };
}
}
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
{
enum ovl_path_type type = ovl_path_type(dentry);
if (!OVL_TYPE_UPPER(type))
ovl_path_lower(dentry, path);
else
ovl_path_upper(dentry, path);
return type;
}
enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path)
{
enum ovl_path_type type = ovl_path_type(dentry);
WARN_ON_ONCE(d_is_dir(dentry));
if (!OVL_TYPE_UPPER(type) || OVL_TYPE_MERGE(type))
ovl_path_lowerdata(dentry, path);
else
ovl_path_upper(dentry, path);
return type;
}
struct dentry *ovl_dentry_upper(struct dentry *dentry)
{
return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
}
struct dentry *ovl_dentry_lower(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return oe->numlower ? oe->lowerstack[0].dentry : NULL;
}
const struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return oe->numlower ? oe->lowerstack[0].layer : NULL;
}
/*
* ovl_dentry_lower() could return either a data dentry or metacopy dentry
* depending on what is stored in lowerstack[0]. At times we need to find
* lower dentry which has data (and not metacopy dentry). This helper
* returns the lower data dentry.
*/
struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return oe->numlower ? oe->lowerstack[oe->numlower - 1].dentry : NULL;
}
struct dentry *ovl_dentry_real(struct dentry *dentry)
{
return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
}
struct dentry *ovl_i_dentry_upper(struct inode *inode)
{
return ovl_upperdentry_dereference(OVL_I(inode));
}
void ovl_i_path_real(struct inode *inode, struct path *path)
{
path->dentry = ovl_i_dentry_upper(inode);
if (!path->dentry) {
path->dentry = OVL_I(inode)->lowerpath.dentry;
path->mnt = OVL_I(inode)->lowerpath.layer->mnt;
} else {
path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
}
}
struct inode *ovl_inode_upper(struct inode *inode)
{
struct dentry *upperdentry = ovl_i_dentry_upper(inode);
return upperdentry ? d_inode(upperdentry) : NULL;
}
struct inode *ovl_inode_lower(struct inode *inode)
{
struct dentry *lowerdentry = OVL_I(inode)->lowerpath.dentry;
return lowerdentry ? d_inode(lowerdentry) : NULL;
}
struct inode *ovl_inode_real(struct inode *inode)
{
return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
}
/* Return inode which contains lower data. Do not return metacopy */
struct inode *ovl_inode_lowerdata(struct inode *inode)
{
if (WARN_ON(!S_ISREG(inode->i_mode)))
return NULL;
return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode);
}
/* Return real inode which contains data. Does not return metacopy inode */
struct inode *ovl_inode_realdata(struct inode *inode)
{
struct inode *upperinode;
upperinode = ovl_inode_upper(inode);
if (upperinode && ovl_has_upperdata(inode))
return upperinode;
return ovl_inode_lowerdata(inode);
}
struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
{
return OVL_I(inode)->cache;
}
void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)
{
OVL_I(inode)->cache = cache;
}
void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry)
{
set_bit(flag, &OVL_E(dentry)->flags);
}
void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry)
{
clear_bit(flag, &OVL_E(dentry)->flags);
}
bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry)
{
return test_bit(flag, &OVL_E(dentry)->flags);
}
bool ovl_dentry_is_opaque(struct dentry *dentry)
{
return ovl_dentry_test_flag(OVL_E_OPAQUE, dentry);
}
bool ovl_dentry_is_whiteout(struct dentry *dentry)
{
return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
}
void ovl_dentry_set_opaque(struct dentry *dentry)
{
ovl_dentry_set_flag(OVL_E_OPAQUE, dentry);
}
/*
* For hard links and decoded file handles, it's possible for ovl_dentry_upper()
* to return positive, while there's no actual upper alias for the inode.
* Copy up code needs to know about the existence of the upper alias, so it
* can't use ovl_dentry_upper().
*/
bool ovl_dentry_has_upper_alias(struct dentry *dentry)
{
return ovl_dentry_test_flag(OVL_E_UPPER_ALIAS, dentry);
}
void ovl_dentry_set_upper_alias(struct dentry *dentry)
{
ovl_dentry_set_flag(OVL_E_UPPER_ALIAS, dentry);
}
static bool ovl_should_check_upperdata(struct inode *inode)
{
if (!S_ISREG(inode->i_mode))
return false;
if (!ovl_inode_lower(inode))
return false;
return true;
}
bool ovl_has_upperdata(struct inode *inode)
{
if (!ovl_should_check_upperdata(inode))
return true;
if (!ovl_test_flag(OVL_UPPERDATA, inode))
return false;
/*
* Pairs with smp_wmb() in ovl_set_upperdata(). Main user of
* ovl_has_upperdata() is ovl_copy_up_meta_inode_data(). Make sure
* if setting of OVL_UPPERDATA is visible, then effects of writes
* before that are visible too.
*/
smp_rmb();
return true;
}
void ovl_set_upperdata(struct inode *inode)
{
/*
* Pairs with smp_rmb() in ovl_has_upperdata(). Make sure
* if OVL_UPPERDATA flag is visible, then effects of write operations
* before it are visible as well.
*/
smp_wmb();
ovl_set_flag(OVL_UPPERDATA, inode);
}
/* Caller should hold ovl_inode->lock */
bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags)
{
if (!ovl_open_flags_need_copy_up(flags))
return false;
return !ovl_test_flag(OVL_UPPERDATA, d_inode(dentry));
}
bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags)
{
if (!ovl_open_flags_need_copy_up(flags))
return false;
return !ovl_has_upperdata(d_inode(dentry));
}
bool ovl_redirect_dir(struct super_block *sb)
{
struct ovl_fs *ofs = sb->s_fs_info;
return ofs->config.redirect_dir && !ofs->noxattr;
}
const char *ovl_dentry_get_redirect(struct dentry *dentry)
{
return OVL_I(d_inode(dentry))->redirect;
}
void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
{
struct ovl_inode *oi = OVL_I(d_inode(dentry));
kfree(oi->redirect);
oi->redirect = redirect;
}
void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
{
struct inode *upperinode = d_inode(upperdentry);
WARN_ON(OVL_I(inode)->__upperdentry);
/*
* Make sure upperdentry is consistent before making it visible
*/
smp_wmb();
OVL_I(inode)->__upperdentry = upperdentry;
if (inode_unhashed(inode)) {
inode->i_private = upperinode;
__insert_inode_hash(inode, (unsigned long) upperinode);
}
}
static void ovl_dir_version_inc(struct dentry *dentry, bool impurity)
{
struct inode *inode = d_inode(dentry);
WARN_ON(!inode_is_locked(inode));
WARN_ON(!d_is_dir(dentry));
/*
* Version is used by readdir code to keep cache consistent.
* For merge dirs (or dirs with origin) all changes need to be noted.
* For non-merge dirs, cache contains only impure entries (i.e. ones
* which have been copied up and have origins), so only need to note
* changes to impure entries.
*/
if (!ovl_dir_is_real(inode) || impurity)
OVL_I(inode)->version++;
}
void ovl_dir_modified(struct dentry *dentry, bool impurity)
{
/* Copy mtime/ctime */
ovl_copyattr(d_inode(dentry));
ovl_dir_version_inc(dentry, impurity);
}
u64 ovl_inode_version_get(struct inode *inode)
{
WARN_ON(!inode_is_locked(inode));
return OVL_I(inode)->version;
}
bool ovl_is_whiteout(struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
return inode && IS_WHITEOUT(inode);
}
struct file *ovl_path_open(const struct path *path, int flags)
{
struct inode *inode = d_inode(path->dentry);
struct mnt_idmap *real_idmap = mnt_idmap(path->mnt);
int err, acc_mode;
if (flags & ~(O_ACCMODE | O_LARGEFILE))
BUG();
switch (flags & O_ACCMODE) {
case O_RDONLY:
acc_mode = MAY_READ;
break;
case O_WRONLY:
acc_mode = MAY_WRITE;
break;
default:
BUG();
}
err = inode_permission(real_idmap, inode, acc_mode | MAY_OPEN);
if (err)
return ERR_PTR(err);
/* O_NOATIME is an optimization, don't fail if not permitted */
if (inode_owner_or_capable(real_idmap, inode))
flags |= O_NOATIME;
return dentry_open(path, flags, current_cred());
}
/* Caller should hold ovl_inode->lock */
static bool ovl_already_copied_up_locked(struct dentry *dentry, int flags)
{
bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
if (ovl_dentry_upper(dentry) &&
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&
!ovl_dentry_needs_data_copy_up_locked(dentry, flags))
return true;
return false;
}
bool ovl_already_copied_up(struct dentry *dentry, int flags)
{
bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
/*
* Check if copy-up has happened as well as for upper alias (in
* case of hard links) is there.
*
* Both checks are lockless:
* - false negatives: will recheck under oi->lock
* - false positives:
* + ovl_dentry_upper() uses memory barriers to ensure the
* upper dentry is up-to-date
* + ovl_dentry_has_upper_alias() relies on locking of
* upper parent i_rwsem to prevent reordering copy-up
* with rename.
*/
if (ovl_dentry_upper(dentry) &&
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&
!ovl_dentry_needs_data_copy_up(dentry, flags))
return true;
return false;
}
int ovl_copy_up_start(struct dentry *dentry, int flags)
{
struct inode *inode = d_inode(dentry);
int err;
err = ovl_inode_lock_interruptible(inode);
if (!err && ovl_already_copied_up_locked(dentry, flags)) {
err = 1; /* Already copied up */
ovl_inode_unlock(inode);
}
return err;
}
void ovl_copy_up_end(struct dentry *dentry)
{
ovl_inode_unlock(d_inode(dentry));
}
bool ovl_path_check_origin_xattr(struct ovl_fs *ofs, const struct path *path)
{
int res;
res = ovl_path_getxattr(ofs, path, OVL_XATTR_ORIGIN, NULL, 0);
/* Zero size value means "copied up but origin unknown" */
if (res >= 0)
return true;
return false;
}
bool ovl_path_check_dir_xattr(struct ovl_fs *ofs, const struct path *path,
enum ovl_xattr ox)
{
int res;
char val;
if (!d_is_dir(path->dentry))
return false;
res = ovl_path_getxattr(ofs, path, ox, &val, 1);
if (res == 1 && val == 'y')
return true;
return false;
}
#define OVL_XATTR_OPAQUE_POSTFIX "opaque"
#define OVL_XATTR_REDIRECT_POSTFIX "redirect"
#define OVL_XATTR_ORIGIN_POSTFIX "origin"
#define OVL_XATTR_IMPURE_POSTFIX "impure"
#define OVL_XATTR_NLINK_POSTFIX "nlink"
#define OVL_XATTR_UPPER_POSTFIX "upper"
#define OVL_XATTR_METACOPY_POSTFIX "metacopy"
#define OVL_XATTR_PROTATTR_POSTFIX "protattr"
#define OVL_XATTR_TAB_ENTRY(x) \
[x] = { [false] = OVL_XATTR_TRUSTED_PREFIX x ## _POSTFIX, \
[true] = OVL_XATTR_USER_PREFIX x ## _POSTFIX }
const char *const ovl_xattr_table[][2] = {
OVL_XATTR_TAB_ENTRY(OVL_XATTR_OPAQUE),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_REDIRECT),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_ORIGIN),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_IMPURE),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_NLINK),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_UPPER),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_PROTATTR),
};
int ovl_check_setxattr(struct ovl_fs *ofs, struct dentry *upperdentry,
enum ovl_xattr ox, const void *value, size_t size,
int xerr)
{
int err;
if (ofs->noxattr)
return xerr;
err = ovl_setxattr(ofs, upperdentry, ox, value, size);
if (err == -EOPNOTSUPP) {
pr_warn("cannot set %s xattr on upper\n", ovl_xattr(ofs, ox));
ofs->noxattr = true;
return xerr;
}
return err;
}
int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
int err;
if (ovl_test_flag(OVL_IMPURE, d_inode(dentry)))
return 0;
/*
* Do not fail when upper doesn't support xattrs.
* Upper inodes won't have origin nor redirect xattr anyway.
*/
err = ovl_check_setxattr(ofs, upperdentry, OVL_XATTR_IMPURE, "y", 1, 0);
if (!err)
ovl_set_flag(OVL_IMPURE, d_inode(dentry));
return err;
}
#define OVL_PROTATTR_MAX 32 /* Reserved for future flags */
void ovl_check_protattr(struct inode *inode, struct dentry *upper)
{
struct ovl_fs *ofs = OVL_FS(inode->i_sb);
u32 iflags = inode->i_flags & OVL_PROT_I_FLAGS_MASK;
char buf[OVL_PROTATTR_MAX+1];
int res, n;
res = ovl_getxattr_upper(ofs, upper, OVL_XATTR_PROTATTR, buf,
OVL_PROTATTR_MAX);
if (res < 0)
return;
/*
* Initialize inode flags from overlay.protattr xattr and upper inode
* flags. If upper inode has those fileattr flags set (i.e. from old
* kernel), we do not clear them on ovl_get_inode(), but we will clear
* them on next fileattr_set().
*/
for (n = 0; n < res; n++) {
if (buf[n] == 'a')
iflags |= S_APPEND;
else if (buf[n] == 'i')
iflags |= S_IMMUTABLE;
else
break;
}
if (!res || n < res) {
pr_warn_ratelimited("incompatible overlay.protattr format (%pd2, len=%d)\n",
upper, res);
} else {
inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
}
}
int ovl_set_protattr(struct inode *inode, struct dentry *upper,
struct fileattr *fa)
{
struct ovl_fs *ofs = OVL_FS(inode->i_sb);
char buf[OVL_PROTATTR_MAX];
int len = 0, err = 0;
u32 iflags = 0;
BUILD_BUG_ON(HWEIGHT32(OVL_PROT_FS_FLAGS_MASK) > OVL_PROTATTR_MAX);
if (fa->flags & FS_APPEND_FL) {
buf[len++] = 'a';
iflags |= S_APPEND;
}
if (fa->flags & FS_IMMUTABLE_FL) {
buf[len++] = 'i';
iflags |= S_IMMUTABLE;
}
/*
* Do not allow to set protection flags when upper doesn't support
* xattrs, because we do not set those fileattr flags on upper inode.
* Remove xattr if it exist and all protection flags are cleared.
*/
if (len) {
err = ovl_check_setxattr(ofs, upper, OVL_XATTR_PROTATTR,
buf, len, -EPERM);
} else if (inode->i_flags & OVL_PROT_I_FLAGS_MASK) {
err = ovl_removexattr(ofs, upper, OVL_XATTR_PROTATTR);
if (err == -EOPNOTSUPP || err == -ENODATA)
err = 0;
}
if (err)
return err;
inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
/* Mask out the fileattr flags that should not be set in upper inode */
fa->flags &= ~OVL_PROT_FS_FLAGS_MASK;
fa->fsx_xflags &= ~OVL_PROT_FSX_FLAGS_MASK;
return 0;
}
/**
* Caller must hold a reference to inode to prevent it from being freed while
* it is marked inuse.
*/
bool ovl_inuse_trylock(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
bool locked = false;
spin_lock(&inode->i_lock);
if (!(inode->i_state & I_OVL_INUSE)) {
inode->i_state |= I_OVL_INUSE;
locked = true;
}
spin_unlock(&inode->i_lock);
return locked;
}
void ovl_inuse_unlock(struct dentry *dentry)
{
if (dentry) {
struct inode *inode = d_inode(dentry);
spin_lock(&inode->i_lock);
WARN_ON(!(inode->i_state & I_OVL_INUSE));
inode->i_state &= ~I_OVL_INUSE;
spin_unlock(&inode->i_lock);
}
}
bool ovl_is_inuse(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
bool inuse;
spin_lock(&inode->i_lock);
inuse = (inode->i_state & I_OVL_INUSE);
spin_unlock(&inode->i_lock);
return inuse;
}
/*
* Does this overlay dentry need to be indexed on copy up?
*/
bool ovl_need_index(struct dentry *dentry)
{
struct dentry *lower = ovl_dentry_lower(dentry);
if (!lower || !ovl_indexdir(dentry->d_sb))
return false;
/* Index all files for NFS export and consistency verification */
if (ovl_index_all(dentry->d_sb))
return true;
/* Index only lower hardlinks on copy up */
if (!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
return true;
return false;
}
/* Caller must hold OVL_I(inode)->lock */
static void ovl_cleanup_index(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
struct inode *dir = indexdir->d_inode;
struct dentry *lowerdentry = ovl_dentry_lower(dentry);
struct dentry *upperdentry = ovl_dentry_upper(dentry);
struct dentry *index = NULL;
struct inode *inode;
struct qstr name = { };
int err;
err = ovl_get_index_name(ofs, lowerdentry, &name);
if (err)
goto fail;
inode = d_inode(upperdentry);
if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) {
pr_warn_ratelimited("cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
upperdentry, inode->i_ino, inode->i_nlink);
/*
* We either have a bug with persistent union nlink or a lower
* hardlink was added while overlay is mounted. Adding a lower
* hardlink and then unlinking all overlay hardlinks would drop
* overlay nlink to zero before all upper inodes are unlinked.
* As a safety measure, when that situation is detected, set
* the overlay nlink to the index inode nlink minus one for the
* index entry itself.
*/
set_nlink(d_inode(dentry), inode->i_nlink - 1);
ovl_set_nlink_upper(dentry);
goto out;
}
inode_lock_nested(dir, I_MUTEX_PARENT);
index = ovl_lookup_upper(ofs, name.name, indexdir, name.len);
err = PTR_ERR(index);
if (IS_ERR(index)) {
index = NULL;
} else if (ovl_index_all(dentry->d_sb)) {
/* Whiteout orphan index to block future open by handle */
err = ovl_cleanup_and_whiteout(OVL_FS(dentry->d_sb),
dir, index);
} else {
/* Cleanup orphan index entries */
err = ovl_cleanup(ofs, dir, index);
}
inode_unlock(dir);
if (err)
goto fail;
out:
kfree(name.name);
dput(index);
return;
fail:
pr_err("cleanup index of '%pd2' failed (%i)\n", dentry, err);
goto out;
}
/*
* Operations that change overlay inode and upper inode nlink need to be
* synchronized with copy up for persistent nlink accounting.
*/
int ovl_nlink_start(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
const struct cred *old_cred;
int err;
if (WARN_ON(!inode))
return -ENOENT;
/*
* With inodes index is enabled, we store the union overlay nlink
* in an xattr on the index inode. When whiting out an indexed lower,
* we need to decrement the overlay persistent nlink, but before the
* first copy up, we have no upper index inode to store the xattr.
*
* As a workaround, before whiteout/rename over an indexed lower,
* copy up to create the upper index. Creating the upper index will
* initialize the overlay nlink, so it could be dropped if unlink
* or rename succeeds.
*
* TODO: implement metadata only index copy up when called with
* ovl_copy_up_flags(dentry, O_PATH).
*/
if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) {
err = ovl_copy_up(dentry);
if (err)
return err;
}
err = ovl_inode_lock_interruptible(inode);
if (err)
return err;
if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
goto out;
old_cred = ovl_override_creds(dentry->d_sb);
/*
* The overlay inode nlink should be incremented/decremented IFF the
* upper operation succeeds, along with nlink change of upper inode.
* Therefore, before link/unlink/rename, we store the union nlink
* value relative to the upper inode nlink in an upper inode xattr.
*/
err = ovl_set_nlink_upper(dentry);
revert_creds(old_cred);
out:
if (err)
ovl_inode_unlock(inode);
return err;
}
void ovl_nlink_end(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) {
const struct cred *old_cred;
old_cred = ovl_override_creds(dentry->d_sb);
ovl_cleanup_index(dentry);
revert_creds(old_cred);
}
ovl_inode_unlock(inode);
}
int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
{
/* Workdir should not be the same as upperdir */
if (workdir == upperdir)
goto err;
/* Workdir should not be subdir of upperdir and vice versa */
if (lock_rename(workdir, upperdir) != NULL)
goto err_unlock;
return 0;
err_unlock:
unlock_rename(workdir, upperdir);
err:
pr_err("failed to lock workdir+upperdir\n");
return -EIO;
}
/* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
int ovl_check_metacopy_xattr(struct ovl_fs *ofs, const struct path *path)
{
int res;
/* Only regular files can have metacopy xattr */
if (!S_ISREG(d_inode(path->dentry)->i_mode))
return 0;
res = ovl_path_getxattr(ofs, path, OVL_XATTR_METACOPY, NULL, 0);
if (res < 0) {
if (res == -ENODATA || res == -EOPNOTSUPP)
return 0;
/*
* getxattr on user.* may fail with EACCES in case there's no
* read permission on the inode. Not much we can do, other than
* tell the caller that this is not a metacopy inode.
*/
if (ofs->config.userxattr && res == -EACCES)
return 0;
goto out;
}
return 1;
out:
pr_warn_ratelimited("failed to get metacopy (%i)\n", res);
return res;
}
bool ovl_is_metacopy_dentry(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
if (!d_is_reg(dentry))
return false;
if (ovl_dentry_upper(dentry)) {
if (!ovl_has_upperdata(d_inode(dentry)))
return true;
return false;
}
return (oe->numlower > 1);
}
char *ovl_get_redirect_xattr(struct ovl_fs *ofs, const struct path *path, int padding)
{
int res;
char *s, *next, *buf = NULL;
res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, NULL, 0);
if (res == -ENODATA || res == -EOPNOTSUPP)
return NULL;
if (res < 0)
goto fail;
if (res == 0)
goto invalid;
buf = kzalloc(res + padding + 1, GFP_KERNEL);
if (!buf)
return ERR_PTR(-ENOMEM);
res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, buf, res);
if (res < 0)
goto fail;
if (res == 0)
goto invalid;
if (buf[0] == '/') {
for (s = buf; *s++ == '/'; s = next) {
next = strchrnul(s, '/');
if (s == next)
goto invalid;
}
} else {
if (strchr(buf, '/') != NULL)
goto invalid;
}
return buf;
invalid:
pr_warn_ratelimited("invalid redirect (%s)\n", buf);
res = -EINVAL;
goto err_free;
fail:
pr_warn_ratelimited("failed to get redirect (%i)\n", res);
err_free:
kfree(buf);
return ERR_PTR(res);
}
/*
* ovl_sync_status() - Check fs sync status for volatile mounts
*
* Returns 1 if this is not a volatile mount and a real sync is required.
*
* Returns 0 if syncing can be skipped because mount is volatile, and no errors
* have occurred on the upperdir since the mount.
*
* Returns -errno if it is a volatile mount, and the error that occurred since
* the last mount. If the error code changes, it'll return the latest error
* code.
*/
int ovl_sync_status(struct ovl_fs *ofs)
{
struct vfsmount *mnt;
if (ovl_should_sync(ofs))
return 1;
mnt = ovl_upper_mnt(ofs);
if (!mnt)
return 0;
return errseq_check(&mnt->mnt_sb->s_wb_err, ofs->errseq);
}
/*
* ovl_copyattr() - copy inode attributes from layer to ovl inode
*
* When overlay copies inode information from an upper or lower layer to the
* relevant overlay inode it will apply the idmapping of the upper or lower
* layer when doing so ensuring that the ovl inode ownership will correctly
* reflect the ownership of the idmapped upper or lower layer. For example, an
* idmapped upper or lower layer mapping id 1001 to id 1000 will take care to
* map any lower or upper inode owned by id 1001 to id 1000. These mapping
* helpers are nops when the relevant layer isn't idmapped.
*/
void ovl_copyattr(struct inode *inode)
{
struct path realpath;
struct inode *realinode;
struct mnt_idmap *real_idmap;
vfsuid_t vfsuid;
vfsgid_t vfsgid;
ovl_i_path_real(inode, &realpath);
realinode = d_inode(realpath.dentry);
real_idmap = mnt_idmap(realpath.mnt);
vfsuid = i_uid_into_vfsuid(real_idmap, realinode);
vfsgid = i_gid_into_vfsgid(real_idmap, realinode);
inode->i_uid = vfsuid_into_kuid(vfsuid);
inode->i_gid = vfsgid_into_kgid(vfsgid);
inode->i_mode = realinode->i_mode;
inode->i_atime = realinode->i_atime;
inode->i_mtime = realinode->i_mtime;
inode->i_ctime = realinode->i_ctime;
i_size_write(inode, i_size_read(realinode));
}