// 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/file.h>
#include <linux/fileattr.h>
#include <linux/uuid.h>
#include <linux/namei.h>
#include <linux/ratelimit.h>
#include "overlayfs.h"
/* Get write access to upper mnt - may fail if upper sb was remounted ro */
int ovl_get_write_access(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
return mnt_get_write_access(ovl_upper_mnt(ofs));
}
/* Get write access to upper sb - may block if upper sb is frozen */
void ovl_start_write(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
sb_start_write(ovl_upper_mnt(ofs)->mnt_sb);
}
int ovl_want_write(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
return mnt_want_write(ovl_upper_mnt(ofs));
}
void ovl_put_write_access(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
mnt_put_write_access(ovl_upper_mnt(ofs));
}
void ovl_end_write(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
sb_end_write(ovl_upper_mnt(ofs)->mnt_sb);
}
void ovl_drop_write(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
mnt_drop_write(ovl_upper_mnt(ofs));
}
struct dentry *ovl_workdir(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
return ofs->workdir;
}
const struct cred *ovl_override_creds(struct super_block *sb)
{
struct ovl_fs *ofs = OVL_FS(sb);
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 (!exportfs_can_decode_fh(sb->s_export_op))
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 = OVL_FS(sb);
return ofs->config.index ? ofs->workdir : NULL;
}
/* 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 = OVL_FS(sb);
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 = OVL_FS(sb);
return ofs->config.nfs_export && ofs->config.index;
}
struct ovl_path *ovl_stack_alloc(unsigned int n)
{
return kcalloc(n, sizeof(struct ovl_path), GFP_KERNEL);
}
void ovl_stack_cpy(struct ovl_path *dst, struct ovl_path *src, unsigned int n)
{
unsigned int i;
memcpy(dst, src, sizeof(struct ovl_path) * n);
for (i = 0; i < n; i++)
dget(src[i].dentry);
}
void ovl_stack_put(struct ovl_path *stack, unsigned int n)
{
unsigned int i;
for (i = 0; stack && i < n; i++)
dput(stack[i].dentry);
}
void ovl_stack_free(struct ovl_path *stack, unsigned int n)
{
ovl_stack_put(stack, n);
kfree(stack);
}
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;
}
void ovl_free_entry(struct ovl_entry *oe)
{
ovl_stack_put(ovl_lowerstack(oe), ovl_numlower(oe));
kfree(oe);
}
#define OVL_D_REVALIDATE (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE)
bool ovl_dentry_remote(struct dentry *dentry)
{
return dentry->d_flags & OVL_D_REVALIDATE;
}
void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry)
{
if (!ovl_dentry_remote(realdentry))
return;
spin_lock(&dentry->d_lock);
dentry->d_flags |= realdentry->d_flags & OVL_D_REVALIDATE;
spin_unlock(&dentry->d_lock);
}
void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry,
struct ovl_entry *oe)
{
return ovl_dentry_init_flags(dentry, upperdentry, oe, OVL_D_REVALIDATE);
}
void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
struct ovl_entry *oe, unsigned int mask)
{
struct ovl_path *lowerstack = ovl_lowerstack(oe);
unsigned int i, flags = 0;
if (upperdentry)
flags |= upperdentry->d_flags;
for (i = 0; i < ovl_numlower(oe) && lowerstack[i].dentry; i++)
flags |= 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 = OVL_E(dentry);
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 (ovl_numlower(oe)) {
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 (ovl_numlower(oe) > 1)
type |= __OVL_PATH_MERGE;
}
return type;
}
void ovl_path_upper(struct dentry *dentry, struct path *path)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
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 = OVL_E(dentry);
struct ovl_path *lowerpath = ovl_lowerstack(oe);
if (ovl_numlower(oe)) {
path->mnt = lowerpath->layer->mnt;
path->dentry = lowerpath->dentry;
} else {
*path = (struct path) { };
}
}
void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
{
struct ovl_entry *oe = OVL_E(dentry);
struct ovl_path *lowerdata = ovl_lowerdata(oe);
struct dentry *lowerdata_dentry = ovl_lowerdata_dentry(oe);
if (lowerdata_dentry) {
path->dentry = lowerdata_dentry;
/*
* Pairs with smp_wmb() in ovl_dentry_set_lowerdata().
* Make sure that if lowerdata->dentry is visible, then
* datapath->layer is visible as well.
*/
smp_rmb();
path->mnt = READ_ONCE(lowerdata->layer)->mnt;
} 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 = OVL_E(dentry);
return ovl_numlower(oe) ? ovl_lowerstack(oe)->dentry : NULL;
}
const struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
{
struct ovl_entry *oe = OVL_E(dentry);
return ovl_numlower(oe) ? ovl_lowerstack(oe)->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)
{
return ovl_lowerdata_dentry(OVL_E(dentry));
}
int ovl_dentry_set_lowerdata(struct dentry *dentry, struct ovl_path *datapath)
{
struct ovl_entry *oe = OVL_E(dentry);
struct ovl_path *lowerdata = ovl_lowerdata(oe);
struct dentry *datadentry = datapath->dentry;
if (WARN_ON_ONCE(ovl_numlower(oe) <= 1))
return -EIO;
WRITE_ONCE(lowerdata->layer, datapath->layer);
/*
* Pairs with smp_rmb() in ovl_path_lowerdata().
* Make sure that if lowerdata->dentry is visible, then
* lowerdata->layer is visible as well.
*/
smp_wmb();
WRITE_ONCE(lowerdata->dentry, dget(datadentry));
ovl_dentry_update_reval(dentry, datadentry);
return 0;
}
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));
}
struct inode *ovl_i_path_real(struct inode *inode, struct path *path)
{
struct ovl_path *lowerpath = ovl_lowerpath(OVL_I_E(inode));
path->dentry = ovl_i_dentry_upper(inode);
if (!path->dentry) {
path->dentry = lowerpath->dentry;
path->mnt = lowerpath->layer->mnt;
} else {
path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
}
return path->dentry ? d_inode_rcu(path->dentry) : NULL;
}
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 ovl_path *lowerpath = ovl_lowerpath(OVL_I_E(inode));
return lowerpath ? d_inode(lowerpath->dentry) : 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)
{
struct dentry *lowerdata = ovl_lowerdata_dentry(OVL_I_E(inode));
if (WARN_ON(!S_ISREG(inode->i_mode)))
return NULL;
return lowerdata ? d_inode(lowerdata) : NULL;
}
/* 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);
}
const char *ovl_lowerdata_redirect(struct inode *inode)
{
return inode && S_ISREG(inode->i_mode) ?
OVL_I(inode)->lowerdata_redirect : NULL;
}
struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
{
return inode && S_ISDIR(inode->i_mode) ? OVL_I(inode)->cache : NULL;
}
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_FLAGS(dentry));
}
void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry)
{
clear_bit(flag, OVL_E_FLAGS(dentry));
}
bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry)
{
return test_bit(flag, OVL_E_FLAGS(dentry));
}
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);
}
bool ovl_dentry_has_xwhiteouts(struct dentry *dentry)
{
return ovl_dentry_test_flag(OVL_E_XWHITEOUTS, dentry);
}
void ovl_dentry_set_xwhiteouts(struct dentry *dentry)
{
ovl_dentry_set_flag(OVL_E_XWHITEOUTS, dentry);
}
/*
* ovl_layer_set_xwhiteouts() is called before adding the overlay dir
* dentry to dcache, while readdir of that same directory happens after
* the overlay dir dentry is in dcache, so if some cpu observes that
* ovl_dentry_is_xwhiteouts(), it will also observe layer->has_xwhiteouts
* for the layers where xwhiteouts marker was found in that merge dir.
*/
void ovl_layer_set_xwhiteouts(struct ovl_fs *ofs,
const struct ovl_layer *layer)
{
if (layer->has_xwhiteouts)
return;
/* Write once to read-mostly layer properties */
ofs->layers[layer->idx].has_xwhiteouts = true;
}
/*
* 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));
}
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);
}
/*
* Use this over ovl_is_whiteout for upper and lower files, as it also
* handles overlay.whiteout xattr whiteout files.
*/
bool ovl_path_is_whiteout(struct ovl_fs *ofs, const struct path *path)
{
return ovl_is_whiteout(path->dentry) ||
ovl_path_check_xwhiteout_xattr(ofs, path);
}
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;
}
/*
* The copy up "transaction" keeps an elevated mnt write count on upper mnt,
* but leaves taking freeze protection on upper sb to lower level helpers.
*/
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)
return err;
if (ovl_already_copied_up_locked(dentry, flags))
err = 1; /* Already copied up */
else
err = ovl_get_write_access(dentry);
if (err)
goto out_unlock;
return 0;
out_unlock:
ovl_inode_unlock(inode);
return err;
}
void ovl_copy_up_end(struct dentry *dentry)
{
ovl_put_write_access(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_xwhiteout_xattr(struct ovl_fs *ofs, const struct path *path)
{
struct dentry *dentry = path->dentry;
int res;
/* xattr.whiteout must be a zero size regular file */
if (!d_is_reg(dentry) || i_size_read(d_inode(dentry)) != 0)
return false;
res = ovl_path_getxattr(ofs, path, OVL_XATTR_XWHITEOUT, NULL, 0);
return res >= 0;
}
/*
* Load persistent uuid from xattr into s_uuid if found, or store a new
* random generated value in s_uuid and in xattr.
*/
bool ovl_init_uuid_xattr(struct super_block *sb, struct ovl_fs *ofs,
const struct path *upperpath)
{
bool set = false;
uuid_t uuid;
int res;
/* Try to load existing persistent uuid */
res = ovl_path_getxattr(ofs, upperpath, OVL_XATTR_UUID, uuid.b,
UUID_SIZE);
if (res == UUID_SIZE)
goto set_uuid;
if (res != -ENODATA)
goto fail;
/*
* With uuid=auto, if uuid xattr is found, it will be used.
* If uuid xattrs is not found, generate a persistent uuid only on mount
* of new overlays where upper root dir is not yet marked as impure.
* An upper dir is marked as impure on copy up or lookup of its subdirs.
*/
if (ofs->config.uuid == OVL_UUID_AUTO) {
res = ovl_path_getxattr(ofs, upperpath, OVL_XATTR_IMPURE, NULL,
0);
if (res > 0) {
/* Any mount of old overlay - downgrade to uuid=null */
ofs->config.uuid = OVL_UUID_NULL;
return true;
} else if (res == -ENODATA) {
/* First mount of new overlay - upgrade to uuid=on */
ofs->config.uuid = OVL_UUID_ON;
} else if (res < 0) {
goto fail;
}
}
/* Generate overlay instance uuid */
uuid_gen(&uuid);
/* Try to store persistent uuid */
set = true;
res = ovl_setxattr(ofs, upperpath->dentry, OVL_XATTR_UUID, uuid.b,
UUID_SIZE);
if (res)
goto fail;
set_uuid:
super_set_uuid(sb, uuid.b, sizeof(uuid));
return true;
fail:
ofs->config.uuid = OVL_UUID_NULL;
pr_warn("failed to %s uuid (%pd2, err=%i); falling back to uuid=null.\n",
set ? "set" : "get", upperpath->dentry, res);
return false;
}
char ovl_get_dir_xattr_val(struct ovl_fs *ofs, const struct path *path,
enum ovl_xattr ox)
{
int res;
char val;
if (!d_is_dir(path->dentry))
return 0;
res = ovl_path_getxattr(ofs, path, ox, &val, 1);
return res == 1 ? val : 0;
}
#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_UUID_POSTFIX "uuid"
#define OVL_XATTR_METACOPY_POSTFIX "metacopy"
#define OVL_XATTR_PROTATTR_POSTFIX "protattr"
#define OVL_XATTR_XWHITEOUT_POSTFIX "whiteout"
#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_UUID),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_PROTATTR),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_XWHITEOUT),
};
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 = { };
bool got_write = false;
int err;
err = ovl_get_index_name(ofs, lowerdentry, &name);
if (err)
goto fail;
err = ovl_want_write(dentry);
if (err)
goto fail;
got_write = true;
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:
if (got_write)
ovl_drop_write(dentry);
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;
err = ovl_want_write(dentry);
if (err)
goto out_unlock;
if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
return 0;
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);
if (err)
goto out_drop_write;
return 0;
out_drop_write:
ovl_drop_write(dentry);
out_unlock:
ovl_inode_unlock(inode);
return err;
}
void ovl_nlink_end(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
ovl_drop_write(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)
{
struct dentry *trap;
/* Workdir should not be the same as upperdir */
if (workdir == upperdir)
goto err;
/* Workdir should not be subdir of upperdir and vice versa */
trap = lock_rename(workdir, upperdir);
if (IS_ERR(trap))
goto err;
if (trap)
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, metacopy data size if xattr found.
* an empty xattr returns OVL_METACOPY_MIN_SIZE to distinguish from no xattr value.
*/
int ovl_check_metacopy_xattr(struct ovl_fs *ofs, const struct path *path,
struct ovl_metacopy *data)
{
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,
data, data ? OVL_METACOPY_MAX_SIZE : 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;
}
if (res == 0) {
/* Emulate empty data for zero size metacopy xattr */
res = OVL_METACOPY_MIN_SIZE;
if (data) {
memset(data, 0, res);
data->len = res;
}
} else if (res < OVL_METACOPY_MIN_SIZE) {
pr_warn_ratelimited("metacopy file '%pd' has too small xattr\n",
path->dentry);
return -EIO;
} else if (data) {
if (data->version != 0) {
pr_warn_ratelimited("metacopy file '%pd' has unsupported version\n",
path->dentry);
return -EIO;
}
if (res != data->len) {
pr_warn_ratelimited("metacopy file '%pd' has invalid xattr size\n",
path->dentry);
return -EIO;
}
}
return res;
out:
pr_warn_ratelimited("failed to get metacopy (%i)\n", res);
return res;
}
int ovl_set_metacopy_xattr(struct ovl_fs *ofs, struct dentry *d, struct ovl_metacopy *metacopy)
{
size_t len = metacopy->len;
/* If no flags or digest fall back to empty metacopy file */
if (metacopy->version == 0 && metacopy->flags == 0 && metacopy->digest_algo == 0)
len = 0;
return ovl_check_setxattr(ofs, d, OVL_XATTR_METACOPY,
metacopy, len, -EOPNOTSUPP);
}
bool ovl_is_metacopy_dentry(struct dentry *dentry)
{
struct ovl_entry *oe = OVL_E(dentry);
if (!d_is_reg(dentry))
return false;
if (ovl_dentry_upper(dentry)) {
if (!ovl_has_upperdata(d_inode(dentry)))
return true;
return false;
}
return (ovl_numlower(oe) > 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);
}
/* Call with mounter creds as it may open the file */
int ovl_ensure_verity_loaded(struct path *datapath)
{
struct inode *inode = d_inode(datapath->dentry);
struct file *filp;
if (!fsverity_active(inode) && IS_VERITY(inode)) {
/*
* If this inode was not yet opened, the verity info hasn't been
* loaded yet, so we need to do that here to force it into memory.
*/
filp = kernel_file_open(datapath, O_RDONLY, current_cred());
if (IS_ERR(filp))
return PTR_ERR(filp);
fput(filp);
}
return 0;
}
int ovl_validate_verity(struct ovl_fs *ofs,
struct path *metapath,
struct path *datapath)
{
struct ovl_metacopy metacopy_data;
u8 actual_digest[FS_VERITY_MAX_DIGEST_SIZE];
int xattr_digest_size, digest_size;
int xattr_size, err;
u8 verity_algo;
if (!ofs->config.verity_mode ||
/* Verity only works on regular files */
!S_ISREG(d_inode(metapath->dentry)->i_mode))
return 0;
xattr_size = ovl_check_metacopy_xattr(ofs, metapath, &metacopy_data);
if (xattr_size < 0)
return xattr_size;
if (!xattr_size || !metacopy_data.digest_algo) {
if (ofs->config.verity_mode == OVL_VERITY_REQUIRE) {
pr_warn_ratelimited("metacopy file '%pd' has no digest specified\n",
metapath->dentry);
return -EIO;
}
return 0;
}
xattr_digest_size = ovl_metadata_digest_size(&metacopy_data);
err = ovl_ensure_verity_loaded(datapath);
if (err < 0) {
pr_warn_ratelimited("lower file '%pd' failed to load fs-verity info\n",
datapath->dentry);
return -EIO;
}
digest_size = fsverity_get_digest(d_inode(datapath->dentry), actual_digest,
&verity_algo, NULL);
if (digest_size == 0) {
pr_warn_ratelimited("lower file '%pd' has no fs-verity digest\n", datapath->dentry);
return -EIO;
}
if (xattr_digest_size != digest_size ||
metacopy_data.digest_algo != verity_algo ||
memcmp(metacopy_data.digest, actual_digest, xattr_digest_size) != 0) {
pr_warn_ratelimited("lower file '%pd' has the wrong fs-verity digest\n",
datapath->dentry);
return -EIO;
}
return 0;
}
int ovl_get_verity_digest(struct ovl_fs *ofs, struct path *src,
struct ovl_metacopy *metacopy)
{
int err, digest_size;
if (!ofs->config.verity_mode || !S_ISREG(d_inode(src->dentry)->i_mode))
return 0;
err = ovl_ensure_verity_loaded(src);
if (err < 0) {
pr_warn_ratelimited("lower file '%pd' failed to load fs-verity info\n",
src->dentry);
return -EIO;
}
digest_size = fsverity_get_digest(d_inode(src->dentry),
metacopy->digest, &metacopy->digest_algo, NULL);
if (digest_size == 0 ||
WARN_ON_ONCE(digest_size > FS_VERITY_MAX_DIGEST_SIZE)) {
if (ofs->config.verity_mode == OVL_VERITY_REQUIRE) {
pr_warn_ratelimited("lower file '%pd' has no fs-verity digest\n",
src->dentry);
return -EIO;
}
return 0;
}
metacopy->len += digest_size;
return 0;
}
/*
* 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;
realinode = ovl_i_path_real(inode, &realpath);
real_idmap = mnt_idmap(realpath.mnt);
spin_lock(&inode->i_lock);
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_set_atime_to_ts(inode, inode_get_atime(realinode));
inode_set_mtime_to_ts(inode, inode_get_mtime(realinode));
inode_set_ctime_to_ts(inode, inode_get_ctime(realinode));
i_size_write(inode, i_size_read(realinode));
spin_unlock(&inode->i_lock);
}
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