diff options
Diffstat (limited to 'fs/overlayfs/dir.c')
| -rw-r--r-- | fs/overlayfs/dir.c | 1495 |
1 files changed, 1495 insertions, 0 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c new file mode 100644 index 000000000..7beb0af26 --- /dev/null +++ b/fs/overlayfs/dir.c @@ -0,0 +1,1495 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * + * Copyright (C) 2011 Novell Inc. + */ + +#include <linux/fs.h> +#include <linux/namei.h> +#include <linux/xattr.h> +#include <linux/security.h> +#include <linux/cred.h> +#include <linux/module.h> +#include <linux/posix_acl.h> +#include <linux/posix_acl_xattr.h> +#include <linux/atomic.h> +#include <linux/ratelimit.h> +#include <linux/backing-file.h> +#include "overlayfs.h" + +static unsigned short ovl_redirect_max = 256; +module_param_named(redirect_max, ovl_redirect_max, ushort, 0644); +MODULE_PARM_DESC(redirect_max, + "Maximum length of absolute redirect xattr value"); + +static int ovl_set_redirect(struct dentry *dentry, bool samedir); + +static int ovl_cleanup_locked(struct ovl_fs *ofs, struct inode *wdir, + struct dentry *wdentry) +{ + int err; + + dget(wdentry); + if (d_is_dir(wdentry)) + err = ovl_do_rmdir(ofs, wdir, wdentry); + else + err = ovl_do_unlink(ofs, wdir, wdentry); + dput(wdentry); + + if (err) { + pr_err("cleanup of '%pd2' failed (%i)\n", + wdentry, err); + } + + return err; +} + +int ovl_cleanup(struct ovl_fs *ofs, struct dentry *workdir, + struct dentry *wdentry) +{ + wdentry = start_removing_dentry(workdir, wdentry); + if (IS_ERR(wdentry)) + return PTR_ERR(wdentry); + + ovl_cleanup_locked(ofs, workdir->d_inode, wdentry); + end_removing(wdentry); + + return 0; +} + +void ovl_tempname(char name[OVL_TEMPNAME_SIZE]) +{ + static atomic_t temp_id = ATOMIC_INIT(0); + + /* counter is allowed to wrap, since temp dentries are ephemeral */ + snprintf(name, OVL_TEMPNAME_SIZE, "#%x", atomic_inc_return(&temp_id)); +} + +static struct dentry *ovl_start_creating_temp(struct ovl_fs *ofs, + struct dentry *workdir, + char name[OVL_TEMPNAME_SIZE]) +{ + ovl_tempname(name); + return start_creating(ovl_upper_mnt_idmap(ofs), workdir, + &QSTR(name)); +} + +static struct dentry *ovl_whiteout(struct ovl_fs *ofs) +{ + int err; + struct dentry *whiteout, *link; + struct dentry *workdir = ofs->workdir; + struct inode *wdir = workdir->d_inode; + char name[OVL_TEMPNAME_SIZE]; + + guard(mutex)(&ofs->whiteout_lock); + + if (!ofs->whiteout) { + whiteout = ovl_start_creating_temp(ofs, workdir, name); + if (IS_ERR(whiteout)) + return whiteout; + err = ovl_do_whiteout(ofs, wdir, whiteout); + if (!err) + ofs->whiteout = dget(whiteout); + end_creating(whiteout); + if (err) + return ERR_PTR(err); + } + + if (!ofs->no_shared_whiteout) { + link = ovl_start_creating_temp(ofs, workdir, name); + if (IS_ERR(link)) + return link; + err = ovl_do_link(ofs, ofs->whiteout, wdir, link); + if (!err) + whiteout = dget(link); + end_creating(link); + if (!err) + return whiteout; + + if (err != -EMLINK) { + pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%u)\n", + ofs->whiteout->d_inode->i_nlink, + err); + ofs->no_shared_whiteout = true; + } + } + whiteout = ofs->whiteout; + ofs->whiteout = NULL; + return whiteout; +} + +int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct dentry *dir, + struct dentry *dentry) +{ + struct dentry *whiteout; + struct renamedata rd = {}; + int err; + int flags = 0; + + whiteout = ovl_whiteout(ofs); + err = PTR_ERR(whiteout); + if (IS_ERR(whiteout)) + return err; + + if (d_is_dir(dentry)) + flags = RENAME_EXCHANGE; + + rd.mnt_idmap = ovl_upper_mnt_idmap(ofs); + rd.old_parent = ofs->workdir; + rd.new_parent = dir; + rd.flags = flags; + err = start_renaming_two_dentries(&rd, whiteout, dentry); + if (!err) { + err = ovl_do_rename_rd(&rd); + end_renaming(&rd); + } + if (err) + goto kill_whiteout; + if (flags) + ovl_cleanup(ofs, ofs->workdir, dentry); + +out: + dput(whiteout); + return err; + +kill_whiteout: + ovl_cleanup(ofs, ofs->workdir, whiteout); + goto out; +} + +struct dentry *ovl_create_real(struct ovl_fs *ofs, struct dentry *parent, + struct dentry *newdentry, struct qstr *qname, + struct ovl_cattr *attr) +{ + struct inode *dir = parent->d_inode; + int err; + + if (IS_ERR(newdentry)) + return newdentry; + + err = -ESTALE; + if (newdentry->d_inode) + goto out; + + if (attr->hardlink) { + err = ovl_do_link(ofs, attr->hardlink, dir, newdentry); + } else { + switch (attr->mode & S_IFMT) { + case S_IFREG: + err = ovl_do_create(ofs, dir, newdentry, attr->mode); + break; + + case S_IFDIR: + /* mkdir is special... */ + newdentry = ovl_do_mkdir(ofs, dir, newdentry, attr->mode); + err = PTR_ERR_OR_ZERO(newdentry); + /* expect to inherit casefolding from workdir/upperdir */ + if (!err && ofs->casefold != ovl_dentry_casefolded(newdentry)) { + pr_warn_ratelimited("wrong inherited casefold (%pd2)\n", + newdentry); + err = -EINVAL; + } + break; + + case S_IFCHR: + case S_IFBLK: + case S_IFIFO: + case S_IFSOCK: + err = ovl_do_mknod(ofs, dir, newdentry, attr->mode, + attr->rdev); + break; + + case S_IFLNK: + err = ovl_do_symlink(ofs, dir, newdentry, attr->link); + break; + + default: + err = -EPERM; + } + } + if (err) + goto out; + + if (WARN_ON(!newdentry->d_inode)) { + /* + * Not quite sure if non-instantiated dentry is legal or not. + * VFS doesn't seem to care so check and warn here. + */ + err = -EIO; + } else if (d_unhashed(newdentry)) { + struct dentry *d; + /* + * Some filesystems (i.e. casefolded) may return an unhashed + * negative dentry from the ovl_start_creating_upper() call before + * ovl_create_real(). + * In that case, lookup again after making the newdentry + * positive, so ovl_create_upper() always returns a hashed + * positive dentry. We lookup using qname which should be + * the same name as newentry, but is certain not to change. + * As we have to drop the lock before the lookup a race + * could result in a lookup failure. In that case we return + * an error. + */ + end_creating_keep(newdentry); + d = ovl_start_creating_upper(ofs, parent, qname); + + if (IS_ERR_OR_NULL(d)) { + err = d ? PTR_ERR(d) : -ENOENT; + } else if (d->d_inode != newdentry->d_inode) { + err = -EIO; + } else { + dput(newdentry); + return d; + } + end_creating(d); + dput(newdentry); + return ERR_PTR(err); + } +out: + if (err) { + end_creating(newdentry); + return ERR_PTR(err); + } + return newdentry; +} + +struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir, + struct ovl_cattr *attr) +{ + struct dentry *ret; + char name[OVL_TEMPNAME_SIZE]; + + ret = ovl_start_creating_temp(ofs, workdir, name); + if (IS_ERR(ret)) + return ret; + ret = ovl_create_real(ofs, workdir, ret, &QSTR(name), attr); + return end_creating_keep(ret); +} + +static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper, + int xerr) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + int err; + + err = ovl_check_setxattr(ofs, upper, OVL_XATTR_OPAQUE, "y", 1, xerr); + if (!err) + ovl_dentry_set_opaque(dentry); + + return err; +} + +static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry) +{ + /* + * Fail with -EIO when trying to create opaque dir and upper doesn't + * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to + * return a specific error for noxattr case. + */ + return ovl_set_opaque_xerr(dentry, upperdentry, -EIO); +} + +/* + * Common operations required to be done after creation of file on upper. + * If @hardlink is false, then @inode is a pre-allocated inode, we may or + * may not use to instantiate the new dentry. + */ +static int ovl_instantiate(struct dentry *dentry, struct inode *inode, + struct dentry *newdentry, bool hardlink, struct file *tmpfile) +{ + struct ovl_inode_params oip = { + .upperdentry = newdentry, + .newinode = inode, + }; + + ovl_dentry_set_upper_alias(dentry); + ovl_dentry_init_reval(dentry, newdentry, NULL); + + if (!hardlink) { + /* + * ovl_obtain_alias() can be called after ovl_create_real() + * and before we get here, so we may get an inode from cache + * with the same real upperdentry that is not the inode we + * pre-allocated. In this case we will use the cached inode + * to instantiate the new dentry. + * + * XXX: if we ever use ovl_obtain_alias() to decode directory + * file handles, need to use ovl_get_inode_locked() and + * d_instantiate_new() here to prevent from creating two + * hashed directory inode aliases. We then need to return + * the obtained alias to ovl_mkdir(). + */ + inode = ovl_get_inode(dentry->d_sb, &oip); + if (IS_ERR(inode)) + return PTR_ERR(inode); + if (inode == oip.newinode) + ovl_set_flag(OVL_UPPERDATA, inode); + } else { + WARN_ON(ovl_inode_real(inode) != d_inode(newdentry)); + dput(newdentry); + inc_nlink(inode); + } + + if (tmpfile) + d_mark_tmpfile(tmpfile, inode); + + d_instantiate(dentry, inode); + if (inode != oip.newinode) { + pr_warn_ratelimited("newly created inode found in cache (%pd2)\n", + dentry); + } + + /* Force lookup of new upper hardlink to find its lower */ + if (hardlink) + d_drop(dentry); + + return 0; +} + +static bool ovl_type_merge(struct dentry *dentry) +{ + return OVL_TYPE_MERGE(ovl_path_type(dentry)); +} + +static bool ovl_type_origin(struct dentry *dentry) +{ + return OVL_TYPE_ORIGIN(ovl_path_type(dentry)); +} + +static int ovl_create_upper(struct dentry *dentry, struct inode *inode, + struct ovl_cattr *attr) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); + struct dentry *newdentry; + struct qstr qname = QSTR_LEN(dentry->d_name.name, + dentry->d_name.len); + int err; + + newdentry = ovl_start_creating_upper(ofs, upperdir, + &qname); + if (IS_ERR(newdentry)) + return PTR_ERR(newdentry); + newdentry = ovl_create_real(ofs, upperdir, newdentry, &qname, attr); + if (IS_ERR(newdentry)) + return PTR_ERR(newdentry); + + end_creating_keep(newdentry); + + if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry) && + !ovl_allow_offline_changes(ofs)) { + /* Setting opaque here is just an optimization, allow to fail */ + ovl_set_opaque(dentry, newdentry); + } + + ovl_dir_modified(dentry->d_parent, false); + err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink, NULL); + if (err) + goto out_cleanup; + return 0; + +out_cleanup: + ovl_cleanup(ofs, upperdir, newdentry); + dput(newdentry); + return err; +} + +static struct dentry *ovl_clear_empty(struct dentry *dentry, + struct list_head *list) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + struct dentry *workdir = ovl_workdir(dentry); + struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); + struct renamedata rd = {}; + struct path upperpath; + struct dentry *upper; + struct dentry *opaquedir; + struct kstat stat; + int err; + + if (WARN_ON(!workdir)) + return ERR_PTR(-EROFS); + + ovl_path_upper(dentry, &upperpath); + err = vfs_getattr(&upperpath, &stat, + STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT); + if (err) + goto out; + + err = -ESTALE; + if (!S_ISDIR(stat.mode)) + goto out; + upper = upperpath.dentry; + + opaquedir = ovl_create_temp(ofs, workdir, OVL_CATTR(stat.mode)); + err = PTR_ERR(opaquedir); + if (IS_ERR(opaquedir)) + goto out; + + rd.mnt_idmap = ovl_upper_mnt_idmap(ofs); + rd.old_parent = workdir; + rd.new_parent = upperdir; + rd.flags = RENAME_EXCHANGE; + err = start_renaming_two_dentries(&rd, opaquedir, upper); + if (err) + goto out_cleanup_unlocked; + + err = ovl_copy_xattr(dentry->d_sb, &upperpath, opaquedir); + if (err) + goto out_cleanup; + + err = ovl_set_opaque(dentry, opaquedir); + if (err) + goto out_cleanup; + + inode_lock(opaquedir->d_inode); + err = ovl_set_attr(ofs, opaquedir, &stat); + inode_unlock(opaquedir->d_inode); + if (err) + goto out_cleanup; + + err = ovl_do_rename_rd(&rd); + end_renaming(&rd); + if (err) + goto out_cleanup_unlocked; + + ovl_cleanup_whiteouts(ofs, upper, list); + ovl_cleanup(ofs, workdir, upper); + + /* dentry's upper doesn't match now, get rid of it */ + d_drop(dentry); + + return opaquedir; + +out_cleanup: + end_renaming(&rd); +out_cleanup_unlocked: + ovl_cleanup(ofs, workdir, opaquedir); + dput(opaquedir); +out: + return ERR_PTR(err); +} + +static int ovl_set_upper_acl(struct ovl_fs *ofs, struct dentry *upperdentry, + const char *acl_name, struct posix_acl *acl) +{ + if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl) + return 0; + + return ovl_do_set_acl(ofs, upperdentry, acl_name, acl); +} + +static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode, + struct ovl_cattr *cattr) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + struct dentry *workdir = ovl_workdir(dentry); + struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); + struct renamedata rd = {}; + struct dentry *upper; + struct dentry *newdentry; + int err; + struct posix_acl *acl, *default_acl; + bool hardlink = !!cattr->hardlink; + + if (WARN_ON(!workdir)) + return -EROFS; + + if (!hardlink) { + err = posix_acl_create(dentry->d_parent->d_inode, + &cattr->mode, &default_acl, &acl); + if (err) + return err; + } + + upper = ovl_lookup_upper_unlocked(ofs, dentry->d_name.name, upperdir, + dentry->d_name.len); + err = PTR_ERR(upper); + if (IS_ERR(upper)) + goto out; + + err = -ESTALE; + if (d_is_negative(upper) || !ovl_upper_is_whiteout(ofs, upper)) + goto out_dput; + + newdentry = ovl_create_temp(ofs, workdir, cattr); + err = PTR_ERR(newdentry); + if (IS_ERR(newdentry)) + goto out_dput; + + rd.mnt_idmap = ovl_upper_mnt_idmap(ofs); + rd.old_parent = workdir; + rd.new_parent = upperdir; + rd.flags = 0; + err = start_renaming_two_dentries(&rd, newdentry, upper); + if (err) + goto out_cleanup_unlocked; + + /* + * mode could have been mutilated due to umask (e.g. sgid directory) + */ + if (!hardlink && + !S_ISLNK(cattr->mode) && + newdentry->d_inode->i_mode != cattr->mode) { + struct iattr attr = { + .ia_valid = ATTR_MODE, + .ia_mode = cattr->mode, + }; + inode_lock(newdentry->d_inode); + err = ovl_do_notify_change(ofs, newdentry, &attr); + inode_unlock(newdentry->d_inode); + if (err) + goto out_cleanup; + } + if (!hardlink) { + err = ovl_set_upper_acl(ofs, newdentry, + XATTR_NAME_POSIX_ACL_ACCESS, acl); + if (err) + goto out_cleanup; + + err = ovl_set_upper_acl(ofs, newdentry, + XATTR_NAME_POSIX_ACL_DEFAULT, default_acl); + if (err) + goto out_cleanup; + } + + if (!hardlink && S_ISDIR(cattr->mode)) { + err = ovl_set_opaque(dentry, newdentry); + if (err) + goto out_cleanup; + + rd.flags = RENAME_EXCHANGE; + err = ovl_do_rename_rd(&rd); + end_renaming(&rd); + if (err) + goto out_cleanup_unlocked; + + ovl_cleanup(ofs, workdir, upper); + } else { + err = ovl_do_rename_rd(&rd); + end_renaming(&rd); + if (err) + goto out_cleanup_unlocked; + } + ovl_dir_modified(dentry->d_parent, false); + err = ovl_instantiate(dentry, inode, newdentry, hardlink, NULL); + if (err) { + ovl_cleanup(ofs, upperdir, newdentry); + dput(newdentry); + } +out_dput: + dput(upper); +out: + if (!hardlink) { + posix_acl_release(acl); + posix_acl_release(default_acl); + } + return err; + +out_cleanup: + end_renaming(&rd); +out_cleanup_unlocked: + ovl_cleanup(ofs, workdir, newdentry); + dput(newdentry); + goto out_dput; +} + +static const struct cred *ovl_override_creator_creds(const struct cred *original_creds, + struct dentry *dentry, struct inode *inode, umode_t mode) +{ + int err; + + if (WARN_ON_ONCE(current->cred != ovl_creds(dentry->d_sb))) + return ERR_PTR(-EINVAL); + + CLASS(prepare_creds, override_cred)(); + if (!override_cred) + return ERR_PTR(-ENOMEM); + + override_cred->fsuid = inode->i_uid; + override_cred->fsgid = inode->i_gid; + + err = security_dentry_create_files_as(dentry, mode, &dentry->d_name, + original_creds, override_cred); + if (err) + return ERR_PTR(err); + + return override_creds(no_free_ptr(override_cred)); +} + +static void ovl_revert_creator_creds(const struct cred *old_cred) +{ + const struct cred *override_cred; + + override_cred = revert_creds(old_cred); + put_cred(override_cred); +} + +DEFINE_CLASS(ovl_override_creator_creds, + const struct cred *, + if (!IS_ERR_OR_NULL(_T)) ovl_revert_creator_creds(_T), + ovl_override_creator_creds(original_creds, dentry, inode, mode), + const struct cred *original_creds, + struct dentry *dentry, + struct inode *inode, + umode_t mode) + +static int ovl_create_handle_whiteouts(struct dentry *dentry, + struct inode *inode, + struct ovl_cattr *attr) +{ + if (!ovl_dentry_is_whiteout(dentry)) + return ovl_create_upper(dentry, inode, attr); + + return ovl_create_over_whiteout(dentry, inode, attr); +} + +static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, + struct ovl_cattr *attr, bool origin) +{ + int err; + struct dentry *parent = dentry->d_parent; + + scoped_class(override_creds_ovl, original_creds, dentry->d_sb) { + /* + * When linking a file with copy up origin into a new parent, mark the + * new parent dir "impure". + */ + if (origin) { + err = ovl_set_impure(parent, ovl_dentry_upper(parent)); + if (err) + return err; + } + + /* + * In the creation cases(create, mkdir, mknod, symlink), + * ovl should transfer current's fs{u,g}id to underlying + * fs. Because underlying fs want to initialize its new + * inode owner using current's fs{u,g}id. And in this + * case, the @inode is a new inode that is initialized + * in inode_init_owner() to current's fs{u,g}id. So use + * the inode's i_{u,g}id to override the cred's fs{u,g}id. + * + * But in the other hardlink case, ovl_link() does not + * create a new inode, so just use the ovl mounter's + * fs{u,g}id. + */ + + if (attr->hardlink) + return ovl_create_handle_whiteouts(dentry, inode, attr); + + scoped_class(ovl_override_creator_creds, cred, original_creds, dentry, inode, attr->mode) { + if (IS_ERR(cred)) + return PTR_ERR(cred); + return ovl_create_handle_whiteouts(dentry, inode, attr); + } + } + return err; +} + +static int ovl_create_object(struct mnt_idmap *idmap, struct dentry *dentry, + int mode, dev_t rdev, const char *link) +{ + int err; + struct inode *inode; + struct ovl_cattr attr = { + .rdev = rdev, + .link = link, + }; + + err = ovl_copy_up(dentry->d_parent); + if (err) + return err; + + err = ovl_want_write(dentry); + if (err) + goto out; + + /* Preallocate inode to be used by ovl_get_inode() */ + err = -ENOMEM; + inode = ovl_new_inode(dentry->d_sb, mode, rdev); + if (!inode) + goto out_drop_write; + + spin_lock(&inode->i_lock); + inode_state_set(inode, I_CREATING); + spin_unlock(&inode->i_lock); + + inode_init_owner(idmap, inode, dentry->d_parent->d_inode, mode); + attr.mode = inode->i_mode; + + err = ovl_create_or_link(dentry, inode, &attr, false); + /* Did we end up using the preallocated inode? */ + if (inode != d_inode(dentry)) + iput(inode); + +out_drop_write: + ovl_drop_write(dentry); +out: + return err; +} + +static int ovl_create(struct mnt_idmap *idmap, struct inode *dir, + struct dentry *dentry, umode_t mode) +{ + return ovl_create_object(idmap, dentry, (mode & 07777) | S_IFREG, 0, NULL); +} + +static struct dentry *ovl_mkdir(struct mnt_idmap *idmap, struct inode *dir, + struct dentry *dentry, umode_t mode) +{ + return ERR_PTR(ovl_create_object(idmap, dentry, (mode & 07777) | S_IFDIR, 0, NULL)); +} + +static int ovl_mknod(struct mnt_idmap *idmap, struct inode *dir, + struct dentry *dentry, umode_t mode, dev_t rdev) +{ + /* Don't allow creation of "whiteout" on overlay */ + if (S_ISCHR(mode) && rdev == WHITEOUT_DEV) + return -EPERM; + + return ovl_create_object(idmap, dentry, mode, rdev, NULL); +} + +static int ovl_symlink(struct mnt_idmap *idmap, struct inode *dir, + struct dentry *dentry, const char *link) +{ + return ovl_create_object(idmap, dentry, S_IFLNK, 0, link); +} + +static int ovl_set_link_redirect(struct dentry *dentry) +{ + with_ovl_creds(dentry->d_sb) + return ovl_set_redirect(dentry, false); +} + +static int ovl_link(struct dentry *old, struct inode *newdir, + struct dentry *new) +{ + int err; + struct inode *inode; + + err = ovl_copy_up(old); + if (err) + goto out; + + err = ovl_copy_up(new->d_parent); + if (err) + goto out; + + err = ovl_nlink_start(old); + if (err) + goto out; + + if (ovl_is_metacopy_dentry(old)) { + err = ovl_set_link_redirect(old); + if (err) + goto out_nlink_end; + } + + inode = d_inode(old); + ihold(inode); + + err = ovl_create_or_link(new, inode, + &(struct ovl_cattr) {.hardlink = ovl_dentry_upper(old)}, + ovl_type_origin(old)); + if (err) + iput(inode); + +out_nlink_end: + ovl_nlink_end(old); +out: + return err; +} + +static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper) +{ + return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper); +} + +static int ovl_remove_and_whiteout(struct dentry *dentry, + struct list_head *list) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + struct dentry *workdir = ovl_workdir(dentry); + struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); + struct dentry *upper; + struct dentry *opaquedir = NULL; + int err; + + if (WARN_ON(!workdir)) + return -EROFS; + + if (!list_empty(list)) { + opaquedir = ovl_clear_empty(dentry, list); + err = PTR_ERR(opaquedir); + if (IS_ERR(opaquedir)) + goto out; + } + + upper = ovl_lookup_upper_unlocked(ofs, dentry->d_name.name, upperdir, + dentry->d_name.len); + err = PTR_ERR(upper); + if (IS_ERR(upper)) + goto out_dput; + + err = -ESTALE; + if ((opaquedir && upper != opaquedir) || + (!opaquedir && ovl_dentry_upper(dentry) && + !ovl_matches_upper(dentry, upper))) { + goto out_dput_upper; + } + + err = ovl_cleanup_and_whiteout(ofs, upperdir, upper); + if (!err) + ovl_dir_modified(dentry->d_parent, true); + + d_drop(dentry); +out_dput_upper: + dput(upper); +out_dput: + dput(opaquedir); +out: + return err; +} + +static int ovl_remove_upper(struct dentry *dentry, bool is_dir, + struct list_head *list) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); + struct inode *dir = upperdir->d_inode; + struct dentry *upper; + struct dentry *opaquedir = NULL; + int err; + + if (!list_empty(list)) { + opaquedir = ovl_clear_empty(dentry, list); + err = PTR_ERR(opaquedir); + if (IS_ERR(opaquedir)) + goto out; + } + + upper = ovl_start_removing_upper(ofs, upperdir, + &QSTR_LEN(dentry->d_name.name, + dentry->d_name.len)); + err = PTR_ERR(upper); + if (IS_ERR(upper)) + goto out_dput; + + err = -ESTALE; + if ((opaquedir && upper != opaquedir) || + (!opaquedir && !ovl_matches_upper(dentry, upper))) + goto out_unlock; + + if (is_dir) + err = ovl_do_rmdir(ofs, dir, upper); + else + err = ovl_do_unlink(ofs, dir, upper); + ovl_dir_modified(dentry->d_parent, ovl_type_origin(dentry)); + + /* + * Keeping this dentry hashed would mean having to release + * upperpath/lowerpath, which could only be done if we are the + * sole user of this dentry. Too tricky... Just unhash for + * now. + */ + if (!err) + d_drop(dentry); +out_unlock: + end_removing(upper); +out_dput: + dput(opaquedir); +out: + return err; +} + +static bool ovl_pure_upper(struct dentry *dentry) +{ + return !ovl_dentry_lower(dentry) && + !ovl_test_flag(OVL_WHITEOUTS, d_inode(dentry)); +} + +static void ovl_drop_nlink(struct dentry *dentry) +{ + struct inode *inode = d_inode(dentry); + struct dentry *alias; + + /* Try to find another, hashed alias */ + spin_lock(&inode->i_lock); + for_each_alias(alias, inode) { + if (alias != dentry && !d_unhashed(alias)) + break; + } + spin_unlock(&inode->i_lock); + + /* + * Changes to underlying layers may cause i_nlink to lose sync with + * reality. In this case prevent the link count from going to zero + * prematurely. + */ + if (inode->i_nlink > !!alias) + drop_nlink(inode); +} + +static int ovl_do_remove(struct dentry *dentry, bool is_dir) +{ + int err; + bool lower_positive = ovl_lower_positive(dentry); + LIST_HEAD(list); + + /* No need to clean pure upper removed by vfs_rmdir() */ + if (is_dir && (lower_positive || !ovl_pure_upper(dentry))) { + err = ovl_check_empty_dir(dentry, &list); + if (err) + goto out; + } + + err = ovl_copy_up(dentry->d_parent); + if (err) + goto out; + + err = ovl_nlink_start(dentry); + if (err) + goto out; + + with_ovl_creds(dentry->d_sb) { + if (!lower_positive) + err = ovl_remove_upper(dentry, is_dir, &list); + else + err = ovl_remove_and_whiteout(dentry, &list); + } + if (!err) { + if (is_dir) + clear_nlink(dentry->d_inode); + else + ovl_drop_nlink(dentry); + } + ovl_nlink_end(dentry); + + /* + * Copy ctime + * + * Note: we fail to update ctime if there was no copy-up, only a + * whiteout + */ + if (ovl_dentry_upper(dentry)) + ovl_copyattr(d_inode(dentry)); + +out: + ovl_cache_free(&list); + return err; +} + +static int ovl_unlink(struct inode *dir, struct dentry *dentry) +{ + return ovl_do_remove(dentry, false); +} + +static int ovl_rmdir(struct inode *dir, struct dentry *dentry) +{ + return ovl_do_remove(dentry, true); +} + +static bool ovl_type_merge_or_lower(struct dentry *dentry) +{ + enum ovl_path_type type = ovl_path_type(dentry); + + return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type); +} + +static bool ovl_can_move(struct dentry *dentry) +{ + return ovl_redirect_dir(OVL_FS(dentry->d_sb)) || + !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry); +} + +static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect) +{ + char *buf, *ret; + struct dentry *d, *tmp; + int buflen = ovl_redirect_max + 1; + + if (!abs_redirect) { + ret = kstrndup(dentry->d_name.name, dentry->d_name.len, + GFP_KERNEL); + goto out; + } + + buf = ret = kmalloc(buflen, GFP_KERNEL); + if (!buf) + goto out; + + buflen--; + buf[buflen] = '\0'; + for (d = dget(dentry); !IS_ROOT(d);) { + const char *name; + int thislen; + + spin_lock(&d->d_lock); + name = ovl_dentry_get_redirect(d); + if (name) { + thislen = strlen(name); + } else { + name = d->d_name.name; + thislen = d->d_name.len; + } + + /* If path is too long, fall back to userspace move */ + if (thislen + (name[0] != '/') > buflen) { + ret = ERR_PTR(-EXDEV); + spin_unlock(&d->d_lock); + goto out_put; + } + + buflen -= thislen; + memcpy(&buf[buflen], name, thislen); + spin_unlock(&d->d_lock); + tmp = dget_parent(d); + + dput(d); + d = tmp; + + /* Absolute redirect: finished */ + if (buf[buflen] == '/') + break; + buflen--; + buf[buflen] = '/'; + } + ret = kstrdup(&buf[buflen], GFP_KERNEL); +out_put: + dput(d); + kfree(buf); +out: + return ret ? ret : ERR_PTR(-ENOMEM); +} + +static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir) +{ + struct dentry *lowerdentry; + + if (!samedir) + return true; + + if (d_is_dir(dentry)) + return false; + + /* + * For non-dir hardlinked files, we need absolute redirects + * in general as two upper hardlinks could be in different + * dirs. We could put a relative redirect now and convert + * it to absolute redirect later. But when nlink > 1 and + * indexing is on, that means relative redirect needs to be + * converted to absolute during copy up of another lower + * hardllink as well. + * + * So without optimizing too much, just check if lower is + * a hard link or not. If lower is hard link, put absolute + * redirect. + */ + lowerdentry = ovl_dentry_lower(dentry); + return (d_inode(lowerdentry)->i_nlink > 1); +} + +static int ovl_set_redirect(struct dentry *dentry, bool samedir) +{ + int err; + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + const char *redirect = ovl_dentry_get_redirect(dentry); + bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir); + + if (redirect && (!absolute_redirect || redirect[0] == '/')) + return 0; + + redirect = ovl_get_redirect(dentry, absolute_redirect); + if (IS_ERR(redirect)) + return PTR_ERR(redirect); + + err = ovl_check_setxattr(ofs, ovl_dentry_upper(dentry), + OVL_XATTR_REDIRECT, + redirect, strlen(redirect), -EXDEV); + if (!err) { + spin_lock(&dentry->d_lock); + ovl_dentry_set_redirect(dentry, redirect); + spin_unlock(&dentry->d_lock); + } else { + kfree(redirect); + pr_warn_ratelimited("failed to set redirect (%i)\n", + err); + /* Fall back to userspace copy-up */ + err = -EXDEV; + } + return err; +} + +struct ovl_renamedata { + struct renamedata; + struct dentry *opaquedir; + bool cleanup_whiteout; + bool update_nlink; + bool overwrite; +}; + +static int ovl_rename_start(struct ovl_renamedata *ovlrd, struct list_head *list) +{ + struct dentry *old = ovlrd->old_dentry; + struct dentry *new = ovlrd->new_dentry; + bool is_dir = d_is_dir(old); + bool new_is_dir = d_is_dir(new); + int err; + + if (ovlrd->flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE)) + return -EINVAL; + + ovlrd->flags &= ~RENAME_NOREPLACE; + + /* Don't copy up directory trees */ + err = -EXDEV; + if (!ovl_can_move(old)) + return err; + if (!ovlrd->overwrite && !ovl_can_move(new)) + return err; + + if (ovlrd->overwrite && new_is_dir && !ovl_pure_upper(new)) { + err = ovl_check_empty_dir(new, list); + if (err) + return err; + } + + if (ovlrd->overwrite) { + if (ovl_lower_positive(old)) { + if (!ovl_dentry_is_whiteout(new)) { + /* Whiteout source */ + ovlrd->flags |= RENAME_WHITEOUT; + } else { + /* Switch whiteouts */ + ovlrd->flags |= RENAME_EXCHANGE; + } + } else if (is_dir && ovl_dentry_is_whiteout(new)) { + ovlrd->flags |= RENAME_EXCHANGE; + ovlrd->cleanup_whiteout = true; + } + } + + err = ovl_copy_up(old); + if (err) + return err; + + err = ovl_copy_up(new->d_parent); + if (err) + return err; + + if (!ovlrd->overwrite) { + err = ovl_copy_up(new); + if (err) + return err; + } else if (d_inode(new)) { + err = ovl_nlink_start(new); + if (err) + return err; + + ovlrd->update_nlink = true; + } + + if (!ovlrd->update_nlink) { + /* ovl_nlink_start() took ovl_want_write() */ + err = ovl_want_write(old); + if (err) + return err; + } + + return 0; +} + +static int ovl_rename_upper(struct ovl_renamedata *ovlrd, struct list_head *list) +{ + struct dentry *old = ovlrd->old_dentry; + struct dentry *new = ovlrd->new_dentry; + struct ovl_fs *ofs = OVL_FS(old->d_sb); + struct dentry *old_upperdir = ovl_dentry_upper(old->d_parent); + struct dentry *new_upperdir = ovl_dentry_upper(new->d_parent); + bool is_dir = d_is_dir(old); + bool new_is_dir = d_is_dir(new); + bool samedir = old->d_parent == new->d_parent; + struct renamedata rd = {}; + struct dentry *de; + struct dentry *whiteout = NULL; + bool old_opaque, new_opaque; + int err; + + if (!list_empty(list)) { + de = ovl_clear_empty(new, list); + if (IS_ERR(de)) + return PTR_ERR(de); + ovlrd->opaquedir = de; + } + + if (!samedir) { + /* + * When moving a merge dir or non-dir with copy up origin into + * a new parent, we are marking the new parent dir "impure". + * When ovl_iterate() iterates an "impure" upper dir, it will + * lookup the origin inodes of the entries to fill d_ino. + */ + if (ovl_type_origin(old)) { + err = ovl_set_impure(new->d_parent, new_upperdir); + if (err) + return err; + } + if (!ovlrd->overwrite && ovl_type_origin(new)) { + err = ovl_set_impure(old->d_parent, old_upperdir); + if (err) + return err; + } + } + + rd.mnt_idmap = ovl_upper_mnt_idmap(ofs); + rd.old_parent = old_upperdir; + rd.new_parent = new_upperdir; + rd.flags = ovlrd->flags; + + err = start_renaming(&rd, 0, + &QSTR_LEN(old->d_name.name, old->d_name.len), + &QSTR_LEN(new->d_name.name, new->d_name.len)); + if (err) + return err; + + err = -ESTALE; + if (!ovl_matches_upper(old, rd.old_dentry)) + goto out_unlock; + + old_opaque = ovl_dentry_is_opaque(old); + new_opaque = ovl_dentry_is_opaque(new); + + err = -ESTALE; + if (d_inode(new) && ovl_dentry_upper(new)) { + if (ovlrd->opaquedir) { + if (rd.new_dentry != ovlrd->opaquedir) + goto out_unlock; + } else { + if (!ovl_matches_upper(new, rd.new_dentry)) + goto out_unlock; + } + } else { + if (!d_is_negative(rd.new_dentry)) { + if (!new_opaque || !ovl_upper_is_whiteout(ofs, rd.new_dentry)) + goto out_unlock; + } else { + if (ovlrd->flags & RENAME_EXCHANGE) + goto out_unlock; + } + } + + if (rd.old_dentry->d_inode == rd.new_dentry->d_inode) + goto out_unlock; + + err = 0; + if (ovl_type_merge_or_lower(old)) + err = ovl_set_redirect(old, samedir); + else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent)) + err = ovl_set_opaque_xerr(old, rd.old_dentry, -EXDEV); + if (err) + goto out_unlock; + + if (!ovlrd->overwrite && ovl_type_merge_or_lower(new)) + err = ovl_set_redirect(new, samedir); + else if (!ovlrd->overwrite && new_is_dir && !new_opaque && + ovl_type_merge(old->d_parent)) + err = ovl_set_opaque_xerr(new, rd.new_dentry, -EXDEV); + if (err) + goto out_unlock; + + err = ovl_do_rename_rd(&rd); + + if (!err && ovlrd->cleanup_whiteout) + whiteout = dget(rd.new_dentry); + +out_unlock: + end_renaming(&rd); + + if (err) + return err; + + if (whiteout) { + ovl_cleanup(ofs, old_upperdir, whiteout); + dput(whiteout); + } + + if (ovlrd->overwrite && d_inode(new)) { + if (new_is_dir) + clear_nlink(d_inode(new)); + else + ovl_drop_nlink(new); + } + + ovl_dir_modified(old->d_parent, ovl_type_origin(old) || + (!ovlrd->overwrite && ovl_type_origin(new))); + ovl_dir_modified(new->d_parent, ovl_type_origin(old) || + (d_inode(new) && ovl_type_origin(new))); + + /* copy ctime: */ + ovl_copyattr(d_inode(old)); + if (d_inode(new) && ovl_dentry_upper(new)) + ovl_copyattr(d_inode(new)); + + return err; +} + +static void ovl_rename_end(struct ovl_renamedata *ovlrd) +{ + if (ovlrd->update_nlink) + ovl_nlink_end(ovlrd->new_dentry); + else + ovl_drop_write(ovlrd->old_dentry); +} + +static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir, + struct dentry *old, struct inode *newdir, + struct dentry *new, unsigned int flags) +{ + struct ovl_renamedata ovlrd = { + .old_parent = old->d_parent, + .old_dentry = old, + .new_parent = new->d_parent, + .new_dentry = new, + .flags = flags, + .overwrite = !(flags & RENAME_EXCHANGE), + }; + LIST_HEAD(list); + int err; + + err = ovl_rename_start(&ovlrd, &list); + if (!err) { + with_ovl_creds(old->d_sb) + err = ovl_rename_upper(&ovlrd, &list); + ovl_rename_end(&ovlrd); + } + + dput(ovlrd.opaquedir); + ovl_cache_free(&list); + return err; +} + +static int ovl_create_tmpfile(struct file *file, struct dentry *dentry, + struct inode *inode, umode_t mode) +{ + struct path realparentpath; + struct file *realfile; + struct ovl_file *of; + struct dentry *newdentry; + /* It's okay to set O_NOATIME, since the owner will be current fsuid */ + int flags = file->f_flags | OVL_OPEN_FLAGS; + int err; + + scoped_class(override_creds_ovl, original_creds, dentry->d_sb) { + scoped_class(ovl_override_creator_creds, cred, original_creds, dentry, inode, mode) { + if (IS_ERR(cred)) + return PTR_ERR(cred); + + ovl_path_upper(dentry->d_parent, &realparentpath); + realfile = backing_tmpfile_open(file, flags, &realparentpath, + mode, current_cred()); + err = PTR_ERR_OR_ZERO(realfile); + pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err); + if (err) + return err; + + of = ovl_file_alloc(realfile); + if (!of) { + fput(realfile); + return -ENOMEM; + } + + /* ovl_instantiate() consumes the newdentry reference on success */ + newdentry = dget(realfile->f_path.dentry); + err = ovl_instantiate(dentry, inode, newdentry, false, file); + if (!err) { + file->private_data = of; + } else { + dput(newdentry); + ovl_file_free(of); + } + } + } + return err; +} + +static int ovl_dummy_open(struct inode *inode, struct file *file) +{ + return 0; +} + +static int ovl_tmpfile(struct mnt_idmap *idmap, struct inode *dir, + struct file *file, umode_t mode) +{ + int err; + struct dentry *dentry = file->f_path.dentry; + struct inode *inode; + + if (!OVL_FS(dentry->d_sb)->tmpfile) + return -EOPNOTSUPP; + + err = ovl_copy_up(dentry->d_parent); + if (err) + return err; + + err = ovl_want_write(dentry); + if (err) + return err; + + err = -ENOMEM; + inode = ovl_new_inode(dentry->d_sb, mode, 0); + if (!inode) + goto drop_write; + + inode_init_owner(idmap, inode, dir, mode); + err = ovl_create_tmpfile(file, dentry, inode, inode->i_mode); + if (err) + goto put_inode; + + /* + * Check if the preallocated inode was actually used. Having something + * else assigned to the dentry shouldn't happen as that would indicate + * that the backing tmpfile "leaked" out of overlayfs. + */ + err = -EIO; + if (WARN_ON(inode != d_inode(dentry))) + goto put_realfile; + + /* inode reference was transferred to dentry */ + inode = NULL; + err = finish_open(file, dentry, ovl_dummy_open); +put_realfile: + /* Without FMODE_OPENED ->release() won't be called on @file */ + if (!(file->f_mode & FMODE_OPENED)) + ovl_file_free(file->private_data); +put_inode: + iput(inode); +drop_write: + ovl_drop_write(dentry); + return err; +} + +const struct inode_operations ovl_dir_inode_operations = { + .lookup = ovl_lookup, + .mkdir = ovl_mkdir, + .symlink = ovl_symlink, + .unlink = ovl_unlink, + .rmdir = ovl_rmdir, + .rename = ovl_rename, + .link = ovl_link, + .setattr = ovl_setattr, + .create = ovl_create, + .mknod = ovl_mknod, + .permission = ovl_permission, + .getattr = ovl_getattr, + .listxattr = ovl_listxattr, + .get_inode_acl = ovl_get_inode_acl, + .get_acl = ovl_get_acl, + .set_acl = ovl_set_acl, + .update_time = ovl_update_time, + .fileattr_get = ovl_fileattr_get, + .fileattr_set = ovl_fileattr_set, + .tmpfile = ovl_tmpfile, +}; |