diff options
Diffstat (limited to 'fs/overlayfs/dir.c')
| -rw-r--r-- | fs/overlayfs/dir.c | 1317 |
1 files changed, 1317 insertions, 0 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c new file mode 100644 index 000000000..033fc0458 --- /dev/null +++ b/fs/overlayfs/dir.c @@ -0,0 +1,1317 @@ +// 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 "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); + +int ovl_cleanup(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; +} + +struct dentry *ovl_lookup_temp(struct ovl_fs *ofs, struct dentry *workdir) +{ + struct dentry *temp; + char name[20]; + static atomic_t temp_id = ATOMIC_INIT(0); + + /* counter is allowed to wrap, since temp dentries are ephemeral */ + snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id)); + + temp = ovl_lookup_upper(ofs, name, workdir, strlen(name)); + if (!IS_ERR(temp) && temp->d_inode) { + pr_err("workdir/%s already exists\n", name); + dput(temp); + temp = ERR_PTR(-EIO); + } + + return temp; +} + +/* caller holds i_mutex on workdir */ +static struct dentry *ovl_whiteout(struct ovl_fs *ofs) +{ + int err; + struct dentry *whiteout; + struct dentry *workdir = ofs->workdir; + struct inode *wdir = workdir->d_inode; + + if (!ofs->whiteout) { + whiteout = ovl_lookup_temp(ofs, workdir); + if (IS_ERR(whiteout)) + goto out; + + err = ovl_do_whiteout(ofs, wdir, whiteout); + if (err) { + dput(whiteout); + whiteout = ERR_PTR(err); + goto out; + } + ofs->whiteout = whiteout; + } + + if (!ofs->no_shared_whiteout) { + whiteout = ovl_lookup_temp(ofs, workdir); + if (IS_ERR(whiteout)) + goto out; + + err = ovl_do_link(ofs, ofs->whiteout, wdir, whiteout); + if (!err) + goto out; + + if (err != -EMLINK) { + pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n", + ofs->whiteout->d_inode->i_nlink, err); + ofs->no_shared_whiteout = true; + } + dput(whiteout); + } + whiteout = ofs->whiteout; + ofs->whiteout = NULL; +out: + return whiteout; +} + +/* Caller must hold i_mutex on both workdir and dir */ +int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir, + struct dentry *dentry) +{ + struct inode *wdir = ofs->workdir->d_inode; + struct dentry *whiteout; + 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; + + err = ovl_do_rename(ofs, wdir, whiteout, dir, dentry, flags); + if (err) + goto kill_whiteout; + if (flags) + ovl_cleanup(ofs, wdir, dentry); + +out: + dput(whiteout); + return err; + +kill_whiteout: + ovl_cleanup(ofs, wdir, whiteout); + goto out; +} + +int ovl_mkdir_real(struct ovl_fs *ofs, struct inode *dir, + struct dentry **newdentry, umode_t mode) +{ + int err; + struct dentry *d, *dentry = *newdentry; + + err = ovl_do_mkdir(ofs, dir, dentry, mode); + if (err) + return err; + + if (likely(!d_unhashed(dentry))) + return 0; + + /* + * vfs_mkdir() may succeed and leave the dentry passed + * to it unhashed and negative. If that happens, try to + * lookup a new hashed and positive dentry. + */ + d = ovl_lookup_upper(ofs, dentry->d_name.name, dentry->d_parent, + dentry->d_name.len); + if (IS_ERR(d)) { + pr_warn("failed lookup after mkdir (%pd2, err=%i).\n", + dentry, err); + return PTR_ERR(d); + } + dput(dentry); + *newdentry = d; + + return 0; +} + +struct dentry *ovl_create_real(struct ovl_fs *ofs, struct inode *dir, + struct dentry *newdentry, struct ovl_cattr *attr) +{ + 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... */ + err = ovl_mkdir_real(ofs, dir, &newdentry, attr->mode); + 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 && 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; + } +out: + if (err) { + dput(newdentry); + return ERR_PTR(err); + } + return newdentry; +} + +struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir, + struct ovl_cattr *attr) +{ + return ovl_create_real(ofs, d_inode(workdir), + ovl_lookup_temp(ofs, workdir), attr); +} + +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 ovl_inode_params oip = { + .upperdentry = newdentry, + .newinode = inode, + }; + + ovl_dir_modified(dentry->d_parent, false); + 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. + */ + 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); + } + + 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 inode *udir = upperdir->d_inode; + struct dentry *newdentry; + int err; + + if (!attr->hardlink && !IS_POSIXACL(udir)) + attr->mode &= ~current_umask(); + + inode_lock_nested(udir, I_MUTEX_PARENT); + newdentry = ovl_create_real(ofs, udir, + ovl_lookup_upper(ofs, dentry->d_name.name, + upperdir, dentry->d_name.len), + attr); + err = PTR_ERR(newdentry); + if (IS_ERR(newdentry)) + goto out_unlock; + + 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); + } + + err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink); + if (err) + goto out_cleanup; +out_unlock: + inode_unlock(udir); + return err; + +out_cleanup: + ovl_cleanup(ofs, udir, newdentry); + dput(newdentry); + goto out_unlock; +} + +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 inode *wdir = workdir->d_inode; + struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); + struct inode *udir = upperdir->d_inode; + struct path upperpath; + struct dentry *upper; + struct dentry *opaquedir; + struct kstat stat; + int err; + + if (WARN_ON(!workdir)) + return ERR_PTR(-EROFS); + + err = ovl_lock_rename_workdir(workdir, upperdir); + if (err) + goto out; + + ovl_path_upper(dentry, &upperpath); + err = vfs_getattr(&upperpath, &stat, + STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT); + if (err) + goto out_unlock; + + err = -ESTALE; + if (!S_ISDIR(stat.mode)) + goto out_unlock; + upper = upperpath.dentry; + if (upper->d_parent->d_inode != udir) + goto out_unlock; + + opaquedir = ovl_create_temp(ofs, workdir, OVL_CATTR(stat.mode)); + err = PTR_ERR(opaquedir); + if (IS_ERR(opaquedir)) + goto out_unlock; + + 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(ofs, wdir, opaquedir, udir, upper, RENAME_EXCHANGE); + if (err) + goto out_cleanup; + + ovl_cleanup_whiteouts(ofs, upper, list); + ovl_cleanup(ofs, wdir, upper); + unlock_rename(workdir, upperdir); + + /* dentry's upper doesn't match now, get rid of it */ + d_drop(dentry); + + return opaquedir; + +out_cleanup: + ovl_cleanup(ofs, wdir, opaquedir); + dput(opaquedir); +out_unlock: + unlock_rename(workdir, upperdir); +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 inode *wdir = workdir->d_inode; + struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); + struct inode *udir = upperdir->d_inode; + 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; + } + + err = ovl_lock_rename_workdir(workdir, upperdir); + if (err) + goto out; + + upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir, + dentry->d_name.len); + err = PTR_ERR(upper); + if (IS_ERR(upper)) + goto out_unlock; + + err = -ESTALE; + if (d_is_negative(upper) || !IS_WHITEOUT(d_inode(upper))) + goto out_dput; + + newdentry = ovl_create_temp(ofs, workdir, cattr); + err = PTR_ERR(newdentry); + if (IS_ERR(newdentry)) + goto out_dput; + + /* + * 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; + + err = ovl_do_rename(ofs, wdir, newdentry, udir, upper, + RENAME_EXCHANGE); + if (err) + goto out_cleanup; + + ovl_cleanup(ofs, wdir, upper); + } else { + err = ovl_do_rename(ofs, wdir, newdentry, udir, upper, 0); + if (err) + goto out_cleanup; + } + err = ovl_instantiate(dentry, inode, newdentry, hardlink); + if (err) { + ovl_cleanup(ofs, udir, newdentry); + dput(newdentry); + } +out_dput: + dput(upper); +out_unlock: + unlock_rename(workdir, upperdir); +out: + if (!hardlink) { + posix_acl_release(acl); + posix_acl_release(default_acl); + } + return err; + +out_cleanup: + ovl_cleanup(ofs, wdir, newdentry); + dput(newdentry); + goto out_dput; +} + +static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, + struct ovl_cattr *attr, bool origin) +{ + int err; + const struct cred *old_cred; + struct cred *override_cred; + struct dentry *parent = dentry->d_parent; + + err = ovl_copy_up(parent); + if (err) + return err; + + old_cred = ovl_override_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) + goto out_revert_creds; + } + + if (!attr->hardlink) { + err = -ENOMEM; + override_cred = prepare_creds(); + if (!override_cred) + goto out_revert_creds; + /* + * 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. + */ + override_cred->fsuid = inode->i_uid; + override_cred->fsgid = inode->i_gid; + err = security_dentry_create_files_as(dentry, + attr->mode, &dentry->d_name, old_cred, + override_cred); + if (err) { + put_cred(override_cred); + goto out_revert_creds; + } + put_cred(override_creds(override_cred)); + put_cred(override_cred); + } + + if (!ovl_dentry_is_whiteout(dentry)) + err = ovl_create_upper(dentry, inode, attr); + else + err = ovl_create_over_whiteout(dentry, inode, attr); + +out_revert_creds: + revert_creds(old_cred); + return err; +} + +static int ovl_create_object(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_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->i_state |= I_CREATING; + spin_unlock(&inode->i_lock); + + inode_init_owner(&nop_mnt_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, bool excl) +{ + return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL); +} + +static int ovl_mkdir(struct mnt_idmap *idmap, struct inode *dir, + struct dentry *dentry, umode_t mode) +{ + return ovl_create_object(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(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(dentry, S_IFLNK, 0, link); +} + +static int ovl_set_link_redirect(struct dentry *dentry) +{ + const struct cred *old_cred; + int err; + + old_cred = ovl_override_creds(dentry->d_sb); + err = ovl_set_redirect(dentry, false); + revert_creds(old_cred); + + return err; +} + +static int ovl_link(struct dentry *old, struct inode *newdir, + struct dentry *new) +{ + int err; + struct inode *inode; + + err = ovl_want_write(old); + if (err) + goto out; + + err = ovl_copy_up(old); + if (err) + goto out_drop_write; + + err = ovl_copy_up(new->d_parent); + if (err) + goto out_drop_write; + + if (ovl_is_metacopy_dentry(old)) { + err = ovl_set_link_redirect(old); + if (err) + goto out_drop_write; + } + + err = ovl_nlink_start(old); + if (err) + goto out_drop_write; + + 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); + + ovl_nlink_end(old); +out_drop_write: + ovl_drop_write(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; + } + + err = ovl_lock_rename_workdir(workdir, upperdir); + if (err) + goto out_dput; + + upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir, + dentry->d_name.len); + err = PTR_ERR(upper); + if (IS_ERR(upper)) + goto out_unlock; + + 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, d_inode(upperdir), upper); + if (err) + goto out_d_drop; + + ovl_dir_modified(dentry->d_parent, true); +out_d_drop: + d_drop(dentry); +out_dput_upper: + dput(upper); +out_unlock: + unlock_rename(workdir, upperdir); +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; + } + + inode_lock_nested(dir, I_MUTEX_PARENT); + upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir, + dentry->d_name.len); + err = PTR_ERR(upper); + if (IS_ERR(upper)) + goto out_unlock; + + err = -ESTALE; + if ((opaquedir && upper != opaquedir) || + (!opaquedir && !ovl_matches_upper(dentry, upper))) + goto out_dput_upper; + + 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_dput_upper: + dput(upper); +out_unlock: + inode_unlock(dir); + 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); + hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { + 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; + const struct cred *old_cred; + 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_want_write(dentry); + if (err) + goto out; + + err = ovl_copy_up(dentry->d_parent); + if (err) + goto out_drop_write; + + err = ovl_nlink_start(dentry); + if (err) + goto out_drop_write; + + old_cred = ovl_override_creds(dentry->d_sb); + if (!lower_positive) + err = ovl_remove_upper(dentry, is_dir, &list); + else + err = ovl_remove_and_whiteout(dentry, &list); + revert_creds(old_cred); + 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_drop_write: + ovl_drop_write(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; +} + +static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir, + struct dentry *old, struct inode *newdir, + struct dentry *new, unsigned int flags) +{ + int err; + struct dentry *old_upperdir; + struct dentry *new_upperdir; + struct dentry *olddentry; + struct dentry *newdentry; + struct dentry *trap; + bool old_opaque; + bool new_opaque; + bool cleanup_whiteout = false; + bool update_nlink = false; + bool overwrite = !(flags & RENAME_EXCHANGE); + bool is_dir = d_is_dir(old); + bool new_is_dir = d_is_dir(new); + bool samedir = olddir == newdir; + struct dentry *opaquedir = NULL; + const struct cred *old_cred = NULL; + struct ovl_fs *ofs = OVL_FS(old->d_sb); + LIST_HEAD(list); + + err = -EINVAL; + if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE)) + goto out; + + flags &= ~RENAME_NOREPLACE; + + /* Don't copy up directory trees */ + err = -EXDEV; + if (!ovl_can_move(old)) + goto out; + if (!overwrite && !ovl_can_move(new)) + goto out; + + if (overwrite && new_is_dir && !ovl_pure_upper(new)) { + err = ovl_check_empty_dir(new, &list); + if (err) + goto out; + } + + if (overwrite) { + if (ovl_lower_positive(old)) { + if (!ovl_dentry_is_whiteout(new)) { + /* Whiteout source */ + flags |= RENAME_WHITEOUT; + } else { + /* Switch whiteouts */ + flags |= RENAME_EXCHANGE; + } + } else if (is_dir && ovl_dentry_is_whiteout(new)) { + flags |= RENAME_EXCHANGE; + cleanup_whiteout = true; + } + } + + err = ovl_want_write(old); + if (err) + goto out; + + err = ovl_copy_up(old); + if (err) + goto out_drop_write; + + err = ovl_copy_up(new->d_parent); + if (err) + goto out_drop_write; + if (!overwrite) { + err = ovl_copy_up(new); + if (err) + goto out_drop_write; + } else if (d_inode(new)) { + err = ovl_nlink_start(new); + if (err) + goto out_drop_write; + + update_nlink = true; + } + + old_cred = ovl_override_creds(old->d_sb); + + if (!list_empty(&list)) { + opaquedir = ovl_clear_empty(new, &list); + err = PTR_ERR(opaquedir); + if (IS_ERR(opaquedir)) { + opaquedir = NULL; + goto out_revert_creds; + } + } + + old_upperdir = ovl_dentry_upper(old->d_parent); + new_upperdir = ovl_dentry_upper(new->d_parent); + + 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) + goto out_revert_creds; + } + if (!overwrite && ovl_type_origin(new)) { + err = ovl_set_impure(old->d_parent, old_upperdir); + if (err) + goto out_revert_creds; + } + } + + trap = lock_rename(new_upperdir, old_upperdir); + + olddentry = ovl_lookup_upper(ofs, old->d_name.name, old_upperdir, + old->d_name.len); + err = PTR_ERR(olddentry); + if (IS_ERR(olddentry)) + goto out_unlock; + + err = -ESTALE; + if (!ovl_matches_upper(old, olddentry)) + goto out_dput_old; + + newdentry = ovl_lookup_upper(ofs, new->d_name.name, new_upperdir, + new->d_name.len); + err = PTR_ERR(newdentry); + if (IS_ERR(newdentry)) + goto out_dput_old; + + 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 (opaquedir) { + if (newdentry != opaquedir) + goto out_dput; + } else { + if (!ovl_matches_upper(new, newdentry)) + goto out_dput; + } + } else { + if (!d_is_negative(newdentry)) { + if (!new_opaque || !ovl_is_whiteout(newdentry)) + goto out_dput; + } else { + if (flags & RENAME_EXCHANGE) + goto out_dput; + } + } + + if (olddentry == trap) + goto out_dput; + if (newdentry == trap) + goto out_dput; + + if (olddentry->d_inode == newdentry->d_inode) + goto out_dput; + + 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, olddentry, -EXDEV); + if (err) + goto out_dput; + + if (!overwrite && ovl_type_merge_or_lower(new)) + err = ovl_set_redirect(new, samedir); + else if (!overwrite && new_is_dir && !new_opaque && + ovl_type_merge(old->d_parent)) + err = ovl_set_opaque_xerr(new, newdentry, -EXDEV); + if (err) + goto out_dput; + + err = ovl_do_rename(ofs, old_upperdir->d_inode, olddentry, + new_upperdir->d_inode, newdentry, flags); + if (err) + goto out_dput; + + if (cleanup_whiteout) + ovl_cleanup(ofs, old_upperdir->d_inode, newdentry); + + if (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) || + (!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)); + +out_dput: + dput(newdentry); +out_dput_old: + dput(olddentry); +out_unlock: + unlock_rename(new_upperdir, old_upperdir); +out_revert_creds: + revert_creds(old_cred); + if (update_nlink) + ovl_nlink_end(new); +out_drop_write: + ovl_drop_write(old); +out: + dput(opaquedir); + ovl_cache_free(&list); + 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, +}; 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