| /* |
| * |
| * Copyright (C) 2011 Novell Inc. |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 as published by |
| * the Free Software Foundation. |
| */ |
| |
| #include <linux/fs.h> |
| #include <linux/slab.h> |
| #include <linux/cred.h> |
| #include <linux/xattr.h> |
| #include <linux/posix_acl.h> |
| #include <linux/ratelimit.h> |
| #include "overlayfs.h" |
| |
| |
| int ovl_setattr(struct dentry *dentry, struct iattr *attr) |
| { |
| int err; |
| bool full_copy_up = false; |
| struct dentry *upperdentry; |
| const struct cred *old_cred; |
| |
| err = setattr_prepare(dentry, attr); |
| if (err) |
| return err; |
| |
| err = ovl_want_write(dentry); |
| if (err) |
| goto out; |
| |
| if (attr->ia_valid & ATTR_SIZE) { |
| struct inode *realinode = d_inode(ovl_dentry_real(dentry)); |
| |
| err = -ETXTBSY; |
| if (atomic_read(&realinode->i_writecount) < 0) |
| goto out_drop_write; |
| |
| /* Truncate should trigger data copy up as well */ |
| full_copy_up = true; |
| } |
| |
| if (!full_copy_up) |
| err = ovl_copy_up(dentry); |
| else |
| err = ovl_copy_up_with_data(dentry); |
| if (!err) { |
| struct inode *winode = NULL; |
| |
| upperdentry = ovl_dentry_upper(dentry); |
| |
| if (attr->ia_valid & ATTR_SIZE) { |
| winode = d_inode(upperdentry); |
| err = get_write_access(winode); |
| if (err) |
| goto out_drop_write; |
| } |
| |
| if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
| attr->ia_valid &= ~ATTR_MODE; |
| |
| inode_lock(upperdentry->d_inode); |
| old_cred = ovl_override_creds(dentry->d_sb); |
| err = notify_change(upperdentry, attr, NULL); |
| revert_creds(old_cred); |
| if (!err) |
| ovl_copyattr(upperdentry->d_inode, dentry->d_inode); |
| inode_unlock(upperdentry->d_inode); |
| |
| if (winode) |
| put_write_access(winode); |
| } |
| out_drop_write: |
| ovl_drop_write(dentry); |
| out: |
| return err; |
| } |
| |
| static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, |
| struct ovl_layer *lower_layer) |
| { |
| bool samefs = ovl_same_sb(dentry->d_sb); |
| unsigned int xinobits = ovl_xino_bits(dentry->d_sb); |
| |
| if (samefs) { |
| /* |
| * When all layers are on the same fs, all real inode |
| * number are unique, so we use the overlay st_dev, |
| * which is friendly to du -x. |
| */ |
| stat->dev = dentry->d_sb->s_dev; |
| return 0; |
| } else if (xinobits) { |
| unsigned int shift = 64 - xinobits; |
| /* |
| * All inode numbers of underlying fs should not be using the |
| * high xinobits, so we use high xinobits to partition the |
| * overlay st_ino address space. The high bits holds the fsid |
| * (upper fsid is 0). This way overlay inode numbers are unique |
| * and all inodes use overlay st_dev. Inode numbers are also |
| * persistent for a given layer configuration. |
| */ |
| if (stat->ino >> shift) { |
| pr_warn_ratelimited("overlayfs: inode number too big (%pd2, ino=%llu, xinobits=%d)\n", |
| dentry, stat->ino, xinobits); |
| } else { |
| if (lower_layer) |
| stat->ino |= ((u64)lower_layer->fsid) << shift; |
| |
| stat->dev = dentry->d_sb->s_dev; |
| return 0; |
| } |
| } |
| |
| /* The inode could not be mapped to a unified st_ino address space */ |
| if (S_ISDIR(dentry->d_inode->i_mode)) { |
| /* |
| * Always use the overlay st_dev for directories, so 'find |
| * -xdev' will scan the entire overlay mount and won't cross the |
| * overlay mount boundaries. |
| * |
| * If not all layers are on the same fs the pair {real st_ino; |
| * overlay st_dev} is not unique, so use the non persistent |
| * overlay st_ino for directories. |
| */ |
| stat->dev = dentry->d_sb->s_dev; |
| stat->ino = dentry->d_inode->i_ino; |
| } else if (lower_layer && lower_layer->fsid) { |
| /* |
| * For non-samefs setup, if we cannot map all layers st_ino |
| * to a unified address space, we need to make sure that st_dev |
| * is unique per lower fs. Upper layer uses real st_dev and |
| * lower layers use the unique anonymous bdev assigned to the |
| * lower fs. |
| */ |
| stat->dev = lower_layer->fs->pseudo_dev; |
| } |
| |
| return 0; |
| } |
| |
| int ovl_getattr(const struct path *path, struct kstat *stat, |
| u32 request_mask, unsigned int flags) |
| { |
| struct dentry *dentry = path->dentry; |
| enum ovl_path_type type; |
| struct path realpath; |
| const struct cred *old_cred; |
| bool is_dir = S_ISDIR(dentry->d_inode->i_mode); |
| bool samefs = ovl_same_sb(dentry->d_sb); |
| struct ovl_layer *lower_layer = NULL; |
| int err; |
| bool metacopy_blocks = false; |
| |
| metacopy_blocks = ovl_is_metacopy_dentry(dentry); |
| |
| type = ovl_path_real(dentry, &realpath); |
| old_cred = ovl_override_creds(dentry->d_sb); |
| err = vfs_getattr(&realpath, stat, request_mask, flags); |
| if (err) |
| goto out; |
| |
| /* |
| * For non-dir or same fs, we use st_ino of the copy up origin. |
| * This guaranties constant st_dev/st_ino across copy up. |
| * With xino feature and non-samefs, we use st_ino of the copy up |
| * origin masked with high bits that represent the layer id. |
| * |
| * If lower filesystem supports NFS file handles, this also guaranties |
| * persistent st_ino across mount cycle. |
| */ |
| if (!is_dir || samefs || ovl_xino_bits(dentry->d_sb)) { |
| if (!OVL_TYPE_UPPER(type)) { |
| lower_layer = ovl_layer_lower(dentry); |
| } else if (OVL_TYPE_ORIGIN(type)) { |
| struct kstat lowerstat; |
| u32 lowermask = STATX_INO | STATX_BLOCKS | |
| (!is_dir ? STATX_NLINK : 0); |
| |
| ovl_path_lower(dentry, &realpath); |
| err = vfs_getattr(&realpath, &lowerstat, |
| lowermask, flags); |
| if (err) |
| goto out; |
| |
| /* |
| * Lower hardlinks may be broken on copy up to different |
| * upper files, so we cannot use the lower origin st_ino |
| * for those different files, even for the same fs case. |
| * |
| * Similarly, several redirected dirs can point to the |
| * same dir on a lower layer. With the "verify_lower" |
| * feature, we do not use the lower origin st_ino, if |
| * we haven't verified that this redirect is unique. |
| * |
| * With inodes index enabled, it is safe to use st_ino |
| * of an indexed origin. The index validates that the |
| * upper hardlink is not broken and that a redirected |
| * dir is the only redirect to that origin. |
| */ |
| if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) || |
| (!ovl_verify_lower(dentry->d_sb) && |
| (is_dir || lowerstat.nlink == 1))) { |
| lower_layer = ovl_layer_lower(dentry); |
| /* |
| * Cannot use origin st_dev;st_ino because |
| * origin inode content may differ from overlay |
| * inode content. |
| */ |
| if (samefs || lower_layer->fsid) |
| stat->ino = lowerstat.ino; |
| } |
| |
| /* |
| * If we are querying a metacopy dentry and lower |
| * dentry is data dentry, then use the blocks we |
| * queried just now. We don't have to do additional |
| * vfs_getattr(). If lower itself is metacopy, then |
| * additional vfs_getattr() is unavoidable. |
| */ |
| if (metacopy_blocks && |
| realpath.dentry == ovl_dentry_lowerdata(dentry)) { |
| stat->blocks = lowerstat.blocks; |
| metacopy_blocks = false; |
| } |
| } |
| |
| if (metacopy_blocks) { |
| /* |
| * If lower is not same as lowerdata or if there was |
| * no origin on upper, we can end up here. |
| */ |
| struct kstat lowerdatastat; |
| u32 lowermask = STATX_BLOCKS; |
| |
| ovl_path_lowerdata(dentry, &realpath); |
| err = vfs_getattr(&realpath, &lowerdatastat, |
| lowermask, flags); |
| if (err) |
| goto out; |
| stat->blocks = lowerdatastat.blocks; |
| } |
| } |
| |
| err = ovl_map_dev_ino(dentry, stat, lower_layer); |
| if (err) |
| goto out; |
| |
| /* |
| * It's probably not worth it to count subdirs to get the |
| * correct link count. nlink=1 seems to pacify 'find' and |
| * other utilities. |
| */ |
| if (is_dir && OVL_TYPE_MERGE(type)) |
| stat->nlink = 1; |
| |
| /* |
| * Return the overlay inode nlinks for indexed upper inodes. |
| * Overlay inode nlink counts the union of the upper hardlinks |
| * and non-covered lower hardlinks. It does not include the upper |
| * index hardlink. |
| */ |
| if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry))) |
| stat->nlink = dentry->d_inode->i_nlink; |
| |
| out: |
| revert_creds(old_cred); |
| |
| return err; |
| } |
| |
| int ovl_permission(struct inode *inode, int mask) |
| { |
| struct inode *upperinode = ovl_inode_upper(inode); |
| struct inode *realinode = upperinode ?: ovl_inode_lower(inode); |
| const struct cred *old_cred; |
| int err; |
| |
| /* Careful in RCU walk mode */ |
| if (!realinode) { |
| WARN_ON(!(mask & MAY_NOT_BLOCK)); |
| return -ECHILD; |
| } |
| |
| /* |
| * Check overlay inode with the creds of task and underlying inode |
| * with creds of mounter |
| */ |
| err = generic_permission(inode, mask); |
| if (err) |
| return err; |
| |
| old_cred = ovl_override_creds(inode->i_sb); |
| if (!upperinode && |
| !special_file(realinode->i_mode) && mask & MAY_WRITE) { |
| mask &= ~(MAY_WRITE | MAY_APPEND); |
| /* Make sure mounter can read file for copy up later */ |
| mask |= MAY_READ; |
| } |
| err = inode_permission(realinode, mask); |
| revert_creds(old_cred); |
| |
| return err; |
| } |
| |
| static const char *ovl_get_link(struct dentry *dentry, |
| struct inode *inode, |
| struct delayed_call *done) |
| { |
| const struct cred *old_cred; |
| const char *p; |
| |
| if (!dentry) |
| return ERR_PTR(-ECHILD); |
| |
| old_cred = ovl_override_creds(dentry->d_sb); |
| p = vfs_get_link(ovl_dentry_real(dentry), done); |
| revert_creds(old_cred); |
| return p; |
| } |
| |
| bool ovl_is_private_xattr(const char *name) |
| { |
| return strncmp(name, OVL_XATTR_PREFIX, |
| sizeof(OVL_XATTR_PREFIX) - 1) == 0; |
| } |
| |
| int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, |
| const void *value, size_t size, int flags) |
| { |
| int err; |
| struct dentry *upperdentry = ovl_i_dentry_upper(inode); |
| struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry); |
| const struct cred *old_cred; |
| |
| err = ovl_want_write(dentry); |
| if (err) |
| goto out; |
| |
| if (!value && !upperdentry) { |
| old_cred = ovl_override_creds(dentry->d_sb); |
| err = vfs_getxattr(realdentry, name, NULL, 0); |
| revert_creds(old_cred); |
| if (err < 0) |
| goto out_drop_write; |
| } |
| |
| if (!upperdentry) { |
| err = ovl_copy_up(dentry); |
| if (err) |
| goto out_drop_write; |
| |
| realdentry = ovl_dentry_upper(dentry); |
| } |
| |
| old_cred = ovl_override_creds(dentry->d_sb); |
| if (value) |
| err = vfs_setxattr(realdentry, name, value, size, flags); |
| else { |
| WARN_ON(flags != XATTR_REPLACE); |
| err = vfs_removexattr(realdentry, name); |
| } |
| revert_creds(old_cred); |
| |
| /* copy c/mtime */ |
| ovl_copyattr(d_inode(realdentry), inode); |
| |
| out_drop_write: |
| ovl_drop_write(dentry); |
| out: |
| return err; |
| } |
| |
| int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, |
| void *value, size_t size) |
| { |
| ssize_t res; |
| const struct cred *old_cred; |
| struct dentry *realdentry = |
| ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry); |
| |
| old_cred = ovl_override_creds(dentry->d_sb); |
| res = vfs_getxattr(realdentry, name, value, size); |
| revert_creds(old_cred); |
| return res; |
| } |
| |
| static bool ovl_can_list(const char *s) |
| { |
| /* List all non-trusted xatts */ |
| if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0) |
| return true; |
| |
| /* Never list trusted.overlay, list other trusted for superuser only */ |
| return !ovl_is_private_xattr(s) && |
| ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN); |
| } |
| |
| ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) |
| { |
| struct dentry *realdentry = ovl_dentry_real(dentry); |
| ssize_t res; |
| size_t len; |
| char *s; |
| const struct cred *old_cred; |
| |
| old_cred = ovl_override_creds(dentry->d_sb); |
| res = vfs_listxattr(realdentry, list, size); |
| revert_creds(old_cred); |
| if (res <= 0 || size == 0) |
| return res; |
| |
| /* filter out private xattrs */ |
| for (s = list, len = res; len;) { |
| size_t slen = strnlen(s, len) + 1; |
| |
| /* underlying fs providing us with an broken xattr list? */ |
| if (WARN_ON(slen > len)) |
| return -EIO; |
| |
| len -= slen; |
| if (!ovl_can_list(s)) { |
| res -= slen; |
| memmove(s, s + slen, len); |
| } else { |
| s += slen; |
| } |
| } |
| |
| return res; |
| } |
| |
| struct posix_acl *ovl_get_acl(struct inode *inode, int type) |
| { |
| struct inode *realinode = ovl_inode_real(inode); |
| const struct cred *old_cred; |
| struct posix_acl *acl; |
| |
| if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode)) |
| return NULL; |
| |
| old_cred = ovl_override_creds(inode->i_sb); |
| acl = get_acl(realinode, type); |
| revert_creds(old_cred); |
| |
| return acl; |
| } |
| |
| int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags) |
| { |
| if (flags & S_ATIME) { |
| struct ovl_fs *ofs = inode->i_sb->s_fs_info; |
| struct path upperpath = { |
| .mnt = ofs->upper_mnt, |
| .dentry = ovl_upperdentry_dereference(OVL_I(inode)), |
| }; |
| |
| if (upperpath.dentry) { |
| touch_atime(&upperpath); |
| inode->i_atime = d_inode(upperpath.dentry)->i_atime; |
| } |
| } |
| return 0; |
| } |
| |
| static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, |
| u64 start, u64 len) |
| { |
| int err; |
| struct inode *realinode = ovl_inode_real(inode); |
| const struct cred *old_cred; |
| |
| if (!realinode->i_op->fiemap) |
| return -EOPNOTSUPP; |
| |
| old_cred = ovl_override_creds(inode->i_sb); |
| |
| if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC) |
| filemap_write_and_wait(realinode->i_mapping); |
| |
| err = realinode->i_op->fiemap(realinode, fieinfo, start, len); |
| revert_creds(old_cred); |
| |
| return err; |
| } |
| |
| static const struct inode_operations ovl_file_inode_operations = { |
| .setattr = ovl_setattr, |
| .permission = ovl_permission, |
| .getattr = ovl_getattr, |
| .listxattr = ovl_listxattr, |
| .get_acl = ovl_get_acl, |
| .update_time = ovl_update_time, |
| .fiemap = ovl_fiemap, |
| }; |
| |
| static const struct inode_operations ovl_symlink_inode_operations = { |
| .setattr = ovl_setattr, |
| .get_link = ovl_get_link, |
| .getattr = ovl_getattr, |
| .listxattr = ovl_listxattr, |
| .update_time = ovl_update_time, |
| }; |
| |
| static const struct inode_operations ovl_special_inode_operations = { |
| .setattr = ovl_setattr, |
| .permission = ovl_permission, |
| .getattr = ovl_getattr, |
| .listxattr = ovl_listxattr, |
| .get_acl = ovl_get_acl, |
| .update_time = ovl_update_time, |
| }; |
| |
| static const struct address_space_operations ovl_aops = { |
| /* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */ |
| .direct_IO = noop_direct_IO, |
| }; |
| |
| /* |
| * It is possible to stack overlayfs instance on top of another |
| * overlayfs instance as lower layer. We need to annonate the |
| * stackable i_mutex locks according to stack level of the super |
| * block instance. An overlayfs instance can never be in stack |
| * depth 0 (there is always a real fs below it). An overlayfs |
| * inode lock will use the lockdep annotaion ovl_i_mutex_key[depth]. |
| * |
| * For example, here is a snip from /proc/lockdep_chains after |
| * dir_iterate of nested overlayfs: |
| * |
| * [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2) |
| * [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1) |
| * [...] &type->i_mutex_dir_key (stack_depth=0) |
| */ |
| #define OVL_MAX_NESTING FILESYSTEM_MAX_STACK_DEPTH |
| |
| static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode) |
| { |
| #ifdef CONFIG_LOCKDEP |
| static struct lock_class_key ovl_i_mutex_key[OVL_MAX_NESTING]; |
| static struct lock_class_key ovl_i_mutex_dir_key[OVL_MAX_NESTING]; |
| static struct lock_class_key ovl_i_lock_key[OVL_MAX_NESTING]; |
| |
| int depth = inode->i_sb->s_stack_depth - 1; |
| |
| if (WARN_ON_ONCE(depth < 0 || depth >= OVL_MAX_NESTING)) |
| depth = 0; |
| |
| if (S_ISDIR(inode->i_mode)) |
| lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_dir_key[depth]); |
| else |
| lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_key[depth]); |
| |
| lockdep_set_class(&OVL_I(inode)->lock, &ovl_i_lock_key[depth]); |
| #endif |
| } |
| |
| static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev, |
| unsigned long ino, int fsid) |
| { |
| int xinobits = ovl_xino_bits(inode->i_sb); |
| |
| /* |
| * When d_ino is consistent with st_ino (samefs or i_ino has enough |
| * bits to encode layer), set the same value used for st_ino to i_ino, |
| * so inode number exposed via /proc/locks and a like will be |
| * consistent with d_ino and st_ino values. An i_ino value inconsistent |
| * with d_ino also causes nfsd readdirplus to fail. When called from |
| * ovl_new_inode(), ino arg is 0, so i_ino will be updated to real |
| * upper inode i_ino on ovl_inode_init() or ovl_inode_update(). |
| */ |
| if (ovl_same_sb(inode->i_sb) || xinobits) { |
| inode->i_ino = ino; |
| if (xinobits && fsid && !(ino >> (64 - xinobits))) |
| inode->i_ino |= (unsigned long)fsid << (64 - xinobits); |
| } else { |
| inode->i_ino = get_next_ino(); |
| } |
| inode->i_mode = mode; |
| inode->i_flags |= S_NOCMTIME; |
| #ifdef CONFIG_FS_POSIX_ACL |
| inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE; |
| #endif |
| |
| ovl_lockdep_annotate_inode_mutex_key(inode); |
| |
| switch (mode & S_IFMT) { |
| case S_IFREG: |
| inode->i_op = &ovl_file_inode_operations; |
| inode->i_fop = &ovl_file_operations; |
| inode->i_mapping->a_ops = &ovl_aops; |
| break; |
| |
| case S_IFDIR: |
| inode->i_op = &ovl_dir_inode_operations; |
| inode->i_fop = &ovl_dir_operations; |
| break; |
| |
| case S_IFLNK: |
| inode->i_op = &ovl_symlink_inode_operations; |
| break; |
| |
| default: |
| inode->i_op = &ovl_special_inode_operations; |
| init_special_inode(inode, mode, rdev); |
| break; |
| } |
| } |
| |
| /* |
| * With inodes index enabled, an overlay inode nlink counts the union of upper |
| * hardlinks and non-covered lower hardlinks. During the lifetime of a non-pure |
| * upper inode, the following nlink modifying operations can happen: |
| * |
| * 1. Lower hardlink copy up |
| * 2. Upper hardlink created, unlinked or renamed over |
| * 3. Lower hardlink whiteout or renamed over |
| * |
| * For the first, copy up case, the union nlink does not change, whether the |
| * operation succeeds or fails, but the upper inode nlink may change. |
| * Therefore, before copy up, we store the union nlink value relative to the |
| * lower inode nlink in the index inode xattr trusted.overlay.nlink. |
| * |
| * For the second, upper hardlink case, the union nlink should be incremented |
| * or decremented IFF the operation succeeds, aligned with nlink change of the |
| * upper inode. Therefore, before link/unlink/rename, we store the union nlink |
| * value relative to the upper inode nlink in the index inode. |
| * |
| * For the last, lower cover up case, we simplify things by preceding the |
| * whiteout or cover up with copy up. This makes sure that there is an index |
| * upper inode where the nlink xattr can be stored before the copied up upper |
| * entry is unlink. |
| */ |
| #define OVL_NLINK_ADD_UPPER (1 << 0) |
| |
| /* |
| * On-disk format for indexed nlink: |
| * |
| * nlink relative to the upper inode - "U[+-]NUM" |
| * nlink relative to the lower inode - "L[+-]NUM" |
| */ |
| |
| static int ovl_set_nlink_common(struct dentry *dentry, |
| struct dentry *realdentry, const char *format) |
| { |
| struct inode *inode = d_inode(dentry); |
| struct inode *realinode = d_inode(realdentry); |
| char buf[13]; |
| int len; |
| |
| len = snprintf(buf, sizeof(buf), format, |
| (int) (inode->i_nlink - realinode->i_nlink)); |
| |
| if (WARN_ON(len >= sizeof(buf))) |
| return -EIO; |
| |
| return ovl_do_setxattr(ovl_dentry_upper(dentry), |
| OVL_XATTR_NLINK, buf, len, 0); |
| } |
| |
| int ovl_set_nlink_upper(struct dentry *dentry) |
| { |
| return ovl_set_nlink_common(dentry, ovl_dentry_upper(dentry), "U%+i"); |
| } |
| |
| int ovl_set_nlink_lower(struct dentry *dentry) |
| { |
| return ovl_set_nlink_common(dentry, ovl_dentry_lower(dentry), "L%+i"); |
| } |
| |
| unsigned int ovl_get_nlink(struct dentry *lowerdentry, |
| struct dentry *upperdentry, |
| unsigned int fallback) |
| { |
| int nlink_diff; |
| int nlink; |
| char buf[13]; |
| int err; |
| |
| if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1) |
| return fallback; |
| |
| err = vfs_getxattr(upperdentry, OVL_XATTR_NLINK, &buf, sizeof(buf) - 1); |
| if (err < 0) |
| goto fail; |
| |
| buf[err] = '\0'; |
| if ((buf[0] != 'L' && buf[0] != 'U') || |
| (buf[1] != '+' && buf[1] != '-')) |
| goto fail; |
| |
| err = kstrtoint(buf + 1, 10, &nlink_diff); |
| if (err < 0) |
| goto fail; |
| |
| nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink; |
| nlink += nlink_diff; |
| |
| if (nlink <= 0) |
| goto fail; |
| |
| return nlink; |
| |
| fail: |
| pr_warn_ratelimited("overlayfs: failed to get index nlink (%pd2, err=%i)\n", |
| upperdentry, err); |
| return fallback; |
| } |
| |
| struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev) |
| { |
| struct inode *inode; |
| |
| inode = new_inode(sb); |
| if (inode) |
| ovl_fill_inode(inode, mode, rdev, 0, 0); |
| |
| return inode; |
| } |
| |
| static int ovl_inode_test(struct inode *inode, void *data) |
| { |
| return inode->i_private == data; |
| } |
| |
| static int ovl_inode_set(struct inode *inode, void *data) |
| { |
| inode->i_private = data; |
| return 0; |
| } |
| |
| static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry, |
| struct dentry *upperdentry, bool strict) |
| { |
| /* |
| * For directories, @strict verify from lookup path performs consistency |
| * checks, so NULL lower/upper in dentry must match NULL lower/upper in |
| * inode. Non @strict verify from NFS handle decode path passes NULL for |
| * 'unknown' lower/upper. |
| */ |
| if (S_ISDIR(inode->i_mode) && strict) { |
| /* Real lower dir moved to upper layer under us? */ |
| if (!lowerdentry && ovl_inode_lower(inode)) |
| return false; |
| |
| /* Lookup of an uncovered redirect origin? */ |
| if (!upperdentry && ovl_inode_upper(inode)) |
| return false; |
| } |
| |
| /* |
| * Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL. |
| * This happens when finding a copied up overlay inode for a renamed |
| * or hardlinked overlay dentry and lower dentry cannot be followed |
| * by origin because lower fs does not support file handles. |
| */ |
| if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry)) |
| return false; |
| |
| /* |
| * Allow non-NULL __upperdentry in inode even if upperdentry is NULL. |
| * This happens when finding a lower alias for a copied up hard link. |
| */ |
| if (upperdentry && ovl_inode_upper(inode) != d_inode(upperdentry)) |
| return false; |
| |
| return true; |
| } |
| |
| struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real, |
| bool is_upper) |
| { |
| struct inode *inode, *key = d_inode(real); |
| |
| inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key); |
| if (!inode) |
| return NULL; |
| |
| if (!ovl_verify_inode(inode, is_upper ? NULL : real, |
| is_upper ? real : NULL, false)) { |
| iput(inode); |
| return ERR_PTR(-ESTALE); |
| } |
| |
| return inode; |
| } |
| |
| bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir) |
| { |
| struct inode *key = d_inode(dir); |
| struct inode *trap; |
| bool res; |
| |
| trap = ilookup5(sb, (unsigned long) key, ovl_inode_test, key); |
| if (!trap) |
| return false; |
| |
| res = IS_DEADDIR(trap) && !ovl_inode_upper(trap) && |
| !ovl_inode_lower(trap); |
| |
| iput(trap); |
| return res; |
| } |
| |
| /* |
| * Create an inode cache entry for layer root dir, that will intentionally |
| * fail ovl_verify_inode(), so any lookup that will find some layer root |
| * will fail. |
| */ |
| struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir) |
| { |
| struct inode *key = d_inode(dir); |
| struct inode *trap; |
| |
| if (!d_is_dir(dir)) |
| return ERR_PTR(-ENOTDIR); |
| |
| trap = iget5_locked(sb, (unsigned long) key, ovl_inode_test, |
| ovl_inode_set, key); |
| if (!trap) |
| return ERR_PTR(-ENOMEM); |
| |
| if (!(trap->i_state & I_NEW)) { |
| /* Conflicting layer roots? */ |
| iput(trap); |
| return ERR_PTR(-ELOOP); |
| } |
| |
| trap->i_mode = S_IFDIR; |
| trap->i_flags = S_DEAD; |
| unlock_new_inode(trap); |
| |
| return trap; |
| } |
| |
| /* |
| * Does overlay inode need to be hashed by lower inode? |
| */ |
| static bool ovl_hash_bylower(struct super_block *sb, struct dentry *upper, |
| struct dentry *lower, struct dentry *index) |
| { |
| struct ovl_fs *ofs = sb->s_fs_info; |
| |
| /* No, if pure upper */ |
| if (!lower) |
| return false; |
| |
| /* Yes, if already indexed */ |
| if (index) |
| return true; |
| |
| /* Yes, if won't be copied up */ |
| if (!ofs->upper_mnt) |
| return true; |
| |
| /* No, if lower hardlink is or will be broken on copy up */ |
| if ((upper || !ovl_indexdir(sb)) && |
| !d_is_dir(lower) && d_inode(lower)->i_nlink > 1) |
| return false; |
| |
| /* No, if non-indexed upper with NFS export */ |
| if (sb->s_export_op && upper) |
| return false; |
| |
| /* Otherwise, hash by lower inode for fsnotify */ |
| return true; |
| } |
| |
| static struct inode *ovl_iget5(struct super_block *sb, struct inode *newinode, |
| struct inode *key) |
| { |
| return newinode ? inode_insert5(newinode, (unsigned long) key, |
| ovl_inode_test, ovl_inode_set, key) : |
| iget5_locked(sb, (unsigned long) key, |
| ovl_inode_test, ovl_inode_set, key); |
| } |
| |
| struct inode *ovl_get_inode(struct super_block *sb, |
| struct ovl_inode_params *oip) |
| { |
| struct dentry *upperdentry = oip->upperdentry; |
| struct ovl_path *lowerpath = oip->lowerpath; |
| struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL; |
| struct inode *inode; |
| struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL; |
| bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry, |
| oip->index); |
| int fsid = bylower ? lowerpath->layer->fsid : 0; |
| bool is_dir, metacopy = false; |
| unsigned long ino = 0; |
| int err = oip->newinode ? -EEXIST : -ENOMEM; |
| |
| if (!realinode) |
| realinode = d_inode(lowerdentry); |
| |
| /* |
| * Copy up origin (lower) may exist for non-indexed upper, but we must |
| * not use lower as hash key if this is a broken hardlink. |
| */ |
| is_dir = S_ISDIR(realinode->i_mode); |
| if (upperdentry || bylower) { |
| struct inode *key = d_inode(bylower ? lowerdentry : |
| upperdentry); |
| unsigned int nlink = is_dir ? 1 : realinode->i_nlink; |
| |
| inode = ovl_iget5(sb, oip->newinode, key); |
| if (!inode) |
| goto out_err; |
| if (!(inode->i_state & I_NEW)) { |
| /* |
| * Verify that the underlying files stored in the inode |
| * match those in the dentry. |
| */ |
| if (!ovl_verify_inode(inode, lowerdentry, upperdentry, |
| true)) { |
| iput(inode); |
| err = -ESTALE; |
| goto out_err; |
| } |
| |
| dput(upperdentry); |
| kfree(oip->redirect); |
| goto out; |
| } |
| |
| /* Recalculate nlink for non-dir due to indexing */ |
| if (!is_dir) |
| nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink); |
| set_nlink(inode, nlink); |
| ino = key->i_ino; |
| } else { |
| /* Lower hardlink that will be broken on copy up */ |
| inode = new_inode(sb); |
| if (!inode) { |
| err = -ENOMEM; |
| goto out_err; |
| } |
| ino = realinode->i_ino; |
| fsid = lowerpath->layer->fsid; |
| } |
| ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev, ino, fsid); |
| ovl_inode_init(inode, upperdentry, lowerdentry, oip->lowerdata); |
| |
| if (upperdentry && ovl_is_impuredir(upperdentry)) |
| ovl_set_flag(OVL_IMPURE, inode); |
| |
| if (oip->index) |
| ovl_set_flag(OVL_INDEX, inode); |
| |
| if (upperdentry) { |
| err = ovl_check_metacopy_xattr(upperdentry); |
| if (err < 0) |
| goto out_err; |
| metacopy = err; |
| if (!metacopy) |
| ovl_set_flag(OVL_UPPERDATA, inode); |
| } |
| |
| OVL_I(inode)->redirect = oip->redirect; |
| |
| if (bylower) |
| ovl_set_flag(OVL_CONST_INO, inode); |
| |
| /* Check for non-merge dir that may have whiteouts */ |
| if (is_dir) { |
| if (((upperdentry && lowerdentry) || oip->numlower > 1) || |
| ovl_check_origin_xattr(upperdentry ?: lowerdentry)) { |
| ovl_set_flag(OVL_WHITEOUTS, inode); |
| } |
| } |
| |
| if (inode->i_state & I_NEW) |
| unlock_new_inode(inode); |
| out: |
| return inode; |
| |
| out_err: |
| pr_warn_ratelimited("overlayfs: failed to get inode (%i)\n", err); |
| inode = ERR_PTR(err); |
| goto out; |
| } |