// SPDX-License-Identifier: GPL-2.0-only /* * * Copyright (C) 2011 Novell Inc. */ #include <linux/module.h> #include <linux/fs.h> #include <linux/slab.h> #include <linux/file.h> #include <linux/splice.h> #include <linux/xattr.h> #include <linux/security.h> #include <linux/uaccess.h> #include <linux/sched/signal.h> #include <linux/cred.h> #include <linux/namei.h> #include <linux/fdtable.h> #include <linux/ratelimit.h> #include <linux/exportfs.h> #include "overlayfs.h" #define OVL_COPY_UP_CHUNK_SIZE (1 << 20) static int ovl_ccup_set(const char *buf, const struct kernel_param *param) { pr_warn("overlayfs: \"check_copy_up\" module option is obsolete\n"); return 0; } static int ovl_ccup_get(char *buf, const struct kernel_param *param) { return sprintf(buf, "N\n"); } module_param_call(check_copy_up, ovl_ccup_set, ovl_ccup_get, NULL, 0644); MODULE_PARM_DESC(check_copy_up, "Obsolete; does nothing"); int ovl_copy_xattr(struct dentry *old, struct dentry *new) { ssize_t list_size, size, value_size = 0; char *buf, *name, *value = NULL; int uninitialized_var(error); size_t slen; if (!(old->d_inode->i_opflags & IOP_XATTR) || !(new->d_inode->i_opflags & IOP_XATTR)) return 0; list_size = vfs_listxattr(old, NULL, 0); if (list_size <= 0) { if (list_size == -EOPNOTSUPP) return 0; return list_size; } buf = kzalloc(list_size, GFP_KERNEL); if (!buf) return -ENOMEM; list_size = vfs_listxattr(old, buf, list_size); if (list_size <= 0) { error = list_size; goto out; } for (name = buf; list_size; name += slen) { slen = strnlen(name, list_size) + 1; /* underlying fs providing us with an broken xattr list? */ if (WARN_ON(slen > list_size)) { error = -EIO; break; } list_size -= slen; if (ovl_is_private_xattr(name)) continue; retry: size = vfs_getxattr(old, name, value, value_size); if (size == -ERANGE) size = vfs_getxattr(old, name, NULL, 0); if (size < 0) { error = size; break; } if (size > value_size) { void *new; new = krealloc(value, size, GFP_KERNEL); if (!new) { error = -ENOMEM; break; } value = new; value_size = size; goto retry; } error = security_inode_copy_up_xattr(name); if (error < 0 && error != -EOPNOTSUPP) break; if (error == 1) { error = 0; continue; /* Discard */ } error = vfs_setxattr(new, name, value, size, 0); if (error) break; } kfree(value); out: kfree(buf); return error; } static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len) { struct file *old_file; struct file *new_file; loff_t old_pos = 0; loff_t new_pos = 0; loff_t cloned; int error = 0; if (len == 0) return 0; old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY); if (IS_ERR(old_file)) return PTR_ERR(old_file); new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY); if (IS_ERR(new_file)) { error = PTR_ERR(new_file); goto out_fput; } /* Try to use clone_file_range to clone up within the same fs */ cloned = do_clone_file_range(old_file, 0, new_file, 0, len, 0); if (cloned == len) goto out; /* Couldn't clone, so now we try to copy the data */ /* FIXME: copy up sparse files efficiently */ while (len) { size_t this_len = OVL_COPY_UP_CHUNK_SIZE; long bytes; if (len < this_len) this_len = len; if (signal_pending_state(TASK_KILLABLE, current)) { error = -EINTR; break; } bytes = do_splice_direct(old_file, &old_pos, new_file, &new_pos, this_len, SPLICE_F_MOVE); if (bytes <= 0) { error = bytes; break; } WARN_ON(old_pos != new_pos); len -= bytes; } out: if (!error) error = vfs_fsync(new_file, 0); fput(new_file); out_fput: fput(old_file); return error; } static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat) { struct iattr attr = { .ia_valid = ATTR_SIZE, .ia_size = stat->size, }; return notify_change(upperdentry, &attr, NULL); } static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat) { struct iattr attr = { .ia_valid = ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET, .ia_atime = stat->atime, .ia_mtime = stat->mtime, }; return notify_change(upperdentry, &attr, NULL); } int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat) { int err = 0; if (!S_ISLNK(stat->mode)) { struct iattr attr = { .ia_valid = ATTR_MODE, .ia_mode = stat->mode, }; err = notify_change(upperdentry, &attr, NULL); } if (!err) { struct iattr attr = { .ia_valid = ATTR_UID | ATTR_GID, .ia_uid = stat->uid, .ia_gid = stat->gid, }; err = notify_change(upperdentry, &attr, NULL); } if (!err) ovl_set_timestamps(upperdentry, stat); return err; } struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper) { struct ovl_fh *fh; int fh_type, dwords; int buflen = MAX_HANDLE_SZ; uuid_t *uuid = &real->d_sb->s_uuid; int err; /* Make sure the real fid stays 32bit aligned */ BUILD_BUG_ON(OVL_FH_FID_OFFSET % 4); BUILD_BUG_ON(MAX_HANDLE_SZ + OVL_FH_FID_OFFSET > 255); fh = kzalloc(buflen + OVL_FH_FID_OFFSET, GFP_KERNEL); if (!fh) return ERR_PTR(-ENOMEM); /* * We encode a non-connectable file handle for non-dir, because we * only need to find the lower inode number and we don't want to pay * the price or reconnecting the dentry. */ dwords = buflen >> 2; fh_type = exportfs_encode_fh(real, (void *)fh->fb.fid, &dwords, 0); buflen = (dwords << 2); err = -EIO; if (WARN_ON(fh_type < 0) || WARN_ON(buflen > MAX_HANDLE_SZ) || WARN_ON(fh_type == FILEID_INVALID)) goto out_err; fh->fb.version = OVL_FH_VERSION; fh->fb.magic = OVL_FH_MAGIC; fh->fb.type = fh_type; fh->fb.flags = OVL_FH_FLAG_CPU_ENDIAN; /* * When we will want to decode an overlay dentry from this handle * and all layers are on the same fs, if we get a disconncted real * dentry when we decode fid, the only way to tell if we should assign * it to upperdentry or to lowerstack is by checking this flag. */ if (is_upper) fh->fb.flags |= OVL_FH_FLAG_PATH_UPPER; fh->fb.len = sizeof(fh->fb) + buflen; fh->fb.uuid = *uuid; return fh; out_err: kfree(fh); return ERR_PTR(err); } int ovl_set_origin(struct dentry *dentry, struct dentry *lower, struct dentry *upper) { const struct ovl_fh *fh = NULL; int err; /* * When lower layer doesn't support export operations store a 'null' fh, * so we can use the overlay.origin xattr to distignuish between a copy * up and a pure upper inode. */ if (ovl_can_decode_fh(lower->d_sb)) { fh = ovl_encode_real_fh(lower, false); if (IS_ERR(fh)) return PTR_ERR(fh); } /* * Do not fail when upper doesn't support xattrs. */ err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh->buf, fh ? fh->fb.len : 0, 0); kfree(fh); return err; } /* Store file handle of @upper dir in @index dir entry */ static int ovl_set_upper_fh(struct dentry *upper, struct dentry *index) { const struct ovl_fh *fh; int err; fh = ovl_encode_real_fh(upper, true); if (IS_ERR(fh)) return PTR_ERR(fh); err = ovl_do_setxattr(index, OVL_XATTR_UPPER, fh->buf, fh->fb.len, 0); kfree(fh); return err; } /* * Create and install index entry. * * Caller must hold i_mutex on indexdir. */ static int ovl_create_index(struct dentry *dentry, struct dentry *origin, struct dentry *upper) { struct dentry *indexdir = ovl_indexdir(dentry->d_sb); struct inode *dir = d_inode(indexdir); struct dentry *index = NULL; struct dentry *temp = NULL; struct qstr name = { }; int err; /* * For now this is only used for creating index entry for directories, * because non-dir are copied up directly to index and then hardlinked * to upper dir. * * TODO: implement create index for non-dir, so we can call it when * encoding file handle for non-dir in case index does not exist. */ if (WARN_ON(!d_is_dir(dentry))) return -EIO; /* Directory not expected to be indexed before copy up */ if (WARN_ON(ovl_test_flag(OVL_INDEX, d_inode(dentry)))) return -EIO; err = ovl_get_index_name(origin, &name); if (err) return err; temp = ovl_create_temp(indexdir, OVL_CATTR(S_IFDIR | 0)); err = PTR_ERR(temp); if (IS_ERR(temp)) goto free_name; err = ovl_set_upper_fh(upper, temp); if (err) goto out; index = lookup_one_len(name.name, indexdir, name.len); if (IS_ERR(index)) { err = PTR_ERR(index); } else { err = ovl_do_rename(dir, temp, dir, index, 0); dput(index); } out: if (err) ovl_cleanup(dir, temp); dput(temp); free_name: kfree(name.name); return err; } struct ovl_copy_up_ctx { struct dentry *parent; struct dentry *dentry; struct path lowerpath; struct kstat stat; struct kstat pstat; const char *link; struct dentry *destdir; struct qstr destname; struct dentry *workdir; bool origin; bool indexed; bool metacopy; }; static int ovl_link_up(struct ovl_copy_up_ctx *c) { int err; struct dentry *upper; struct dentry *upperdir = ovl_dentry_upper(c->parent); struct inode *udir = d_inode(upperdir); /* Mark parent "impure" because it may now contain non-pure upper */ err = ovl_set_impure(c->parent, upperdir); if (err) return err; err = ovl_set_nlink_lower(c->dentry); if (err) return err; inode_lock_nested(udir, I_MUTEX_PARENT); upper = lookup_one_len(c->dentry->d_name.name, upperdir, c->dentry->d_name.len); err = PTR_ERR(upper); if (!IS_ERR(upper)) { err = ovl_do_link(ovl_dentry_upper(c->dentry), udir, upper); dput(upper); if (!err) { /* Restore timestamps on parent (best effort) */ ovl_set_timestamps(upperdir, &c->pstat); ovl_dentry_set_upper_alias(c->dentry); } } inode_unlock(udir); if (err) return err; err = ovl_set_nlink_upper(c->dentry); return err; } static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp) { int err; /* * Copy up data first and then xattrs. Writing data after * xattrs will remove security.capability xattr automatically. */ if (S_ISREG(c->stat.mode) && !c->metacopy) { struct path upperpath, datapath; ovl_path_upper(c->dentry, &upperpath); if (WARN_ON(upperpath.dentry != NULL)) return -EIO; upperpath.dentry = temp; ovl_path_lowerdata(c->dentry, &datapath); err = ovl_copy_up_data(&datapath, &upperpath, c->stat.size); if (err) return err; } err = ovl_copy_xattr(c->lowerpath.dentry, temp); if (err) return err; /* * Store identifier of lower inode in upper inode xattr to * allow lookup of the copy up origin inode. * * Don't set origin when we are breaking the association with a lower * hard link. */ if (c->origin) { err = ovl_set_origin(c->dentry, c->lowerpath.dentry, temp); if (err) return err; } if (c->metacopy) { err = ovl_check_setxattr(c->dentry, temp, OVL_XATTR_METACOPY, NULL, 0, -EOPNOTSUPP); if (err) return err; } inode_lock(temp->d_inode); if (c->metacopy) err = ovl_set_size(temp, &c->stat); if (!err) err = ovl_set_attr(temp, &c->stat); inode_unlock(temp->d_inode); return err; } struct ovl_cu_creds { const struct cred *old; struct cred *new; }; static int ovl_prep_cu_creds(struct dentry *dentry, struct ovl_cu_creds *cc) { int err; cc->old = cc->new = NULL; err = security_inode_copy_up(dentry, &cc->new); if (err < 0) return err; if (cc->new) cc->old = override_creds(cc->new); return 0; } static void ovl_revert_cu_creds(struct ovl_cu_creds *cc) { if (cc->new) { revert_creds(cc->old); put_cred(cc->new); } } /* * Copyup using workdir to prepare temp file. Used when copying up directories, * special files or when upper fs doesn't support O_TMPFILE. */ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c) { struct inode *inode; struct inode *udir = d_inode(c->destdir), *wdir = d_inode(c->workdir); struct dentry *temp, *upper; struct ovl_cu_creds cc; int err; struct ovl_cattr cattr = { /* Can't properly set mode on creation because of the umask */ .mode = c->stat.mode & S_IFMT, .rdev = c->stat.rdev, .link = c->link }; err = ovl_lock_rename_workdir(c->workdir, c->destdir); if (err) return err; err = ovl_prep_cu_creds(c->dentry, &cc); if (err) goto unlock; temp = ovl_create_temp(c->workdir, &cattr); ovl_revert_cu_creds(&cc); err = PTR_ERR(temp); if (IS_ERR(temp)) goto unlock; err = ovl_copy_up_inode(c, temp); if (err) goto cleanup; if (S_ISDIR(c->stat.mode) && c->indexed) { err = ovl_create_index(c->dentry, c->lowerpath.dentry, temp); if (err) goto cleanup; } upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len); err = PTR_ERR(upper); if (IS_ERR(upper)) goto cleanup; err = ovl_do_rename(wdir, temp, udir, upper, 0); dput(upper); if (err) goto cleanup; if (!c->metacopy) ovl_set_upperdata(d_inode(c->dentry)); inode = d_inode(c->dentry); ovl_inode_update(inode, temp); if (S_ISDIR(inode->i_mode)) ovl_set_flag(OVL_WHITEOUTS, inode); unlock: unlock_rename(c->workdir, c->destdir); return err; cleanup: ovl_cleanup(wdir, temp); dput(temp); goto unlock; } /* Copyup using O_TMPFILE which does not require cross dir locking */ static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c) { struct inode *udir = d_inode(c->destdir); struct dentry *temp, *upper; struct ovl_cu_creds cc; int err; err = ovl_prep_cu_creds(c->dentry, &cc); if (err) return err; temp = ovl_do_tmpfile(c->workdir, c->stat.mode); ovl_revert_cu_creds(&cc); if (IS_ERR(temp)) return PTR_ERR(temp); err = ovl_copy_up_inode(c, temp); if (err) goto out_dput; inode_lock_nested(udir, I_MUTEX_PARENT); upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len); err = PTR_ERR(upper); if (!IS_ERR(upper)) { err = ovl_do_link(temp, udir, upper); dput(upper); } inode_unlock(udir); if (err) goto out_dput; if (!c->metacopy) ovl_set_upperdata(d_inode(c->dentry)); ovl_inode_update(d_inode(c->dentry), temp); return 0; out_dput: dput(temp); return err; } /* * Copy up a single dentry * * All renames start with copy up of source if necessary. The actual * rename will only proceed once the copy up was successful. Copy up uses * upper parent i_mutex for exclusion. Since rename can change d_parent it * is possible that the copy up will lock the old parent. At that point * the file will have already been copied up anyway. */ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) { int err; struct ovl_fs *ofs = c->dentry->d_sb->s_fs_info; bool to_index = false; /* * Indexed non-dir is copied up directly to the index entry and then * hardlinked to upper dir. Indexed dir is copied up to indexdir, * then index entry is created and then copied up dir installed. * Copying dir up to indexdir instead of workdir simplifies locking. */ if (ovl_need_index(c->dentry)) { c->indexed = true; if (S_ISDIR(c->stat.mode)) c->workdir = ovl_indexdir(c->dentry->d_sb); else to_index = true; } if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || to_index) c->origin = true; if (to_index) { c->destdir = ovl_indexdir(c->dentry->d_sb); err = ovl_get_index_name(c->lowerpath.dentry, &c->destname); if (err) return err; } else if (WARN_ON(!c->parent)) { /* Disconnected dentry must be copied up to index dir */ return -EIO; } else { /* * Mark parent "impure" because it may now contain non-pure * upper */ err = ovl_set_impure(c->parent, c->destdir); if (err) return err; } /* Should we copyup with O_TMPFILE or with workdir? */ if (S_ISREG(c->stat.mode) && ofs->tmpfile) err = ovl_copy_up_tmpfile(c); else err = ovl_copy_up_workdir(c); if (err) goto out; if (c->indexed) ovl_set_flag(OVL_INDEX, d_inode(c->dentry)); if (to_index) { /* Initialize nlink for copy up of disconnected dentry */ err = ovl_set_nlink_upper(c->dentry); } else { struct inode *udir = d_inode(c->destdir); /* Restore timestamps on parent (best effort) */ inode_lock(udir); ovl_set_timestamps(c->destdir, &c->pstat); inode_unlock(udir); ovl_dentry_set_upper_alias(c->dentry); } out: if (to_index) kfree(c->destname.name); return err; } static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode, int flags) { struct ovl_fs *ofs = dentry->d_sb->s_fs_info; if (!ofs->config.metacopy) return false; if (!S_ISREG(mode)) return false; if (flags && ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC))) return false; return true; } /* Copy up data of an inode which was copied up metadata only in the past. */ static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c) { struct path upperpath, datapath; int err; char *capability = NULL; ssize_t uninitialized_var(cap_size); ovl_path_upper(c->dentry, &upperpath); if (WARN_ON(upperpath.dentry == NULL)) return -EIO; ovl_path_lowerdata(c->dentry, &datapath); if (WARN_ON(datapath.dentry == NULL)) return -EIO; if (c->stat.size) { err = cap_size = ovl_getxattr(upperpath.dentry, XATTR_NAME_CAPS, &capability, 0); if (err < 0 && err != -ENODATA) goto out; } err = ovl_copy_up_data(&datapath, &upperpath, c->stat.size); if (err) goto out_free; /* * Writing to upper file will clear security.capability xattr. We * don't want that to happen for normal copy-up operation. */ if (capability) { err = ovl_do_setxattr(upperpath.dentry, XATTR_NAME_CAPS, capability, cap_size, 0); if (err) goto out_free; } err = vfs_removexattr(upperpath.dentry, OVL_XATTR_METACOPY); if (err) goto out_free; ovl_set_upperdata(d_inode(c->dentry)); out_free: kfree(capability); out: return err; } static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, int flags) { int err; DEFINE_DELAYED_CALL(done); struct path parentpath; struct ovl_copy_up_ctx ctx = { .parent = parent, .dentry = dentry, .workdir = ovl_workdir(dentry), }; if (WARN_ON(!ctx.workdir)) return -EROFS; ovl_path_lower(dentry, &ctx.lowerpath); err = vfs_getattr(&ctx.lowerpath, &ctx.stat, STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT); if (err) return err; ctx.metacopy = ovl_need_meta_copy_up(dentry, ctx.stat.mode, flags); if (parent) { ovl_path_upper(parent, &parentpath); ctx.destdir = parentpath.dentry; ctx.destname = dentry->d_name; err = vfs_getattr(&parentpath, &ctx.pstat, STATX_ATIME | STATX_MTIME, AT_STATX_SYNC_AS_STAT); if (err) return err; } /* maybe truncate regular file. this has no effect on dirs */ if (flags & O_TRUNC) ctx.stat.size = 0; if (S_ISLNK(ctx.stat.mode)) { ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done); if (IS_ERR(ctx.link)) return PTR_ERR(ctx.link); } err = ovl_copy_up_start(dentry, flags); /* err < 0: interrupted, err > 0: raced with another copy-up */ if (unlikely(err)) { if (err > 0) err = 0; } else { if (!ovl_dentry_upper(dentry)) err = ovl_do_copy_up(&ctx); if (!err && parent && !ovl_dentry_has_upper_alias(dentry)) err = ovl_link_up(&ctx); if (!err && ovl_dentry_needs_data_copy_up_locked(dentry, flags)) err = ovl_copy_up_meta_inode_data(&ctx); ovl_copy_up_end(dentry); } do_delayed_call(&done); return err; } int ovl_copy_up_flags(struct dentry *dentry, int flags) { int err = 0; const struct cred *old_cred = ovl_override_creds(dentry->d_sb); bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED); /* * With NFS export, copy up can get called for a disconnected non-dir. * In this case, we will copy up lower inode to index dir without * linking it to upper dir. */ if (WARN_ON(disconnected && d_is_dir(dentry))) return -EIO; while (!err) { struct dentry *next; struct dentry *parent = NULL; if (ovl_already_copied_up(dentry, flags)) break; next = dget(dentry); /* find the topmost dentry not yet copied up */ for (; !disconnected;) { parent = dget_parent(next); if (ovl_dentry_upper(parent)) break; dput(next); next = parent; } err = ovl_copy_up_one(parent, next, flags); dput(parent); dput(next); } revert_creds(old_cred); return err; } static bool ovl_open_need_copy_up(struct dentry *dentry, int flags) { /* Copy up of disconnected dentry does not set upper alias */ if (ovl_already_copied_up(dentry, flags)) return false; if (special_file(d_inode(dentry)->i_mode)) return false; if (!ovl_open_flags_need_copy_up(flags)) return false; return true; } int ovl_maybe_copy_up(struct dentry *dentry, int flags) { int err = 0; if (ovl_open_need_copy_up(dentry, flags)) { err = ovl_want_write(dentry); if (!err) { err = ovl_copy_up_flags(dentry, flags); ovl_drop_write(dentry); } } return err; } int ovl_copy_up_with_data(struct dentry *dentry) { return ovl_copy_up_flags(dentry, O_WRONLY); } int ovl_copy_up(struct dentry *dentry) { return ovl_copy_up_flags(dentry, 0); }