// SPDX-License-Identifier: MIT /* * VirtualBox Guest Shared Folders support: Virtual File System. * * Module initialization/finalization * File system registration/deregistration * Superblock reading * Few utility functions * * Copyright (C) 2006-2018 Oracle Corporation */ #include <linux/idr.h> #include <linux/fs_parser.h> #include <linux/magic.h> #include <linux/module.h> #include <linux/nls.h> #include <linux/statfs.h> #include <linux/vbox_utils.h> #include "vfsmod.h" #define VBOXSF_SUPER_MAGIC 0x786f4256 /* 'VBox' little endian */ #define VBSF_MOUNT_SIGNATURE_BYTE_0 ('\000') #define VBSF_MOUNT_SIGNATURE_BYTE_1 ('\377') #define VBSF_MOUNT_SIGNATURE_BYTE_2 ('\376') #define VBSF_MOUNT_SIGNATURE_BYTE_3 ('\375') static int follow_symlinks; module_param(follow_symlinks, int, 0444); MODULE_PARM_DESC(follow_symlinks, "Let host resolve symlinks rather than showing them"); static DEFINE_IDA(vboxsf_bdi_ida); static DEFINE_MUTEX(vboxsf_setup_mutex); static bool vboxsf_setup_done; static struct super_operations vboxsf_super_ops; /* forward declaration */ static struct kmem_cache *vboxsf_inode_cachep; static char * const vboxsf_default_nls = CONFIG_NLS_DEFAULT; enum { opt_nls, opt_uid, opt_gid, opt_ttl, opt_dmode, opt_fmode, opt_dmask, opt_fmask }; static const struct fs_parameter_spec vboxsf_fs_parameters[] = { fsparam_string ("nls", opt_nls), fsparam_u32 ("uid", opt_uid), fsparam_u32 ("gid", opt_gid), fsparam_u32 ("ttl", opt_ttl), fsparam_u32oct ("dmode", opt_dmode), fsparam_u32oct ("fmode", opt_fmode), fsparam_u32oct ("dmask", opt_dmask), fsparam_u32oct ("fmask", opt_fmask), {} }; static int vboxsf_parse_param(struct fs_context *fc, struct fs_parameter *param) { struct vboxsf_fs_context *ctx = fc->fs_private; struct fs_parse_result result; kuid_t uid; kgid_t gid; int opt; opt = fs_parse(fc, vboxsf_fs_parameters, param, &result); if (opt < 0) return opt; switch (opt) { case opt_nls: if (ctx->nls_name || fc->purpose != FS_CONTEXT_FOR_MOUNT) { vbg_err("vboxsf: Cannot reconfigure nls option\n"); return -EINVAL; } ctx->nls_name = param->string; param->string = NULL; break; case opt_uid: uid = make_kuid(current_user_ns(), result.uint_32); if (!uid_valid(uid)) return -EINVAL; ctx->o.uid = uid; break; case opt_gid: gid = make_kgid(current_user_ns(), result.uint_32); if (!gid_valid(gid)) return -EINVAL; ctx->o.gid = gid; break; case opt_ttl: ctx->o.ttl = msecs_to_jiffies(result.uint_32); break; case opt_dmode: if (result.uint_32 & ~0777) return -EINVAL; ctx->o.dmode = result.uint_32; ctx->o.dmode_set = true; break; case opt_fmode: if (result.uint_32 & ~0777) return -EINVAL; ctx->o.fmode = result.uint_32; ctx->o.fmode_set = true; break; case opt_dmask: if (result.uint_32 & ~07777) return -EINVAL; ctx->o.dmask = result.uint_32; break; case opt_fmask: if (result.uint_32 & ~07777) return -EINVAL; ctx->o.fmask = result.uint_32; break; default: return -EINVAL; } return 0; } static int vboxsf_fill_super(struct super_block *sb, struct fs_context *fc) { struct vboxsf_fs_context *ctx = fc->fs_private; struct shfl_string *folder_name, root_path; struct vboxsf_sbi *sbi; struct dentry *droot; struct inode *iroot; char *nls_name; size_t size; int err; if (!fc->source) return -EINVAL; sbi = kzalloc(sizeof(*sbi), GFP_KERNEL); if (!sbi) return -ENOMEM; sbi->o = ctx->o; idr_init(&sbi->ino_idr); spin_lock_init(&sbi->ino_idr_lock); sbi->next_generation = 1; sbi->bdi_id = -1; /* Load nls if not utf8 */ nls_name = ctx->nls_name ? ctx->nls_name : vboxsf_default_nls; if (strcmp(nls_name, "utf8") != 0) { if (nls_name == vboxsf_default_nls) sbi->nls = load_nls_default(); else sbi->nls = load_nls(nls_name); if (!sbi->nls) { vbg_err("vboxsf: Count not load '%s' nls\n", nls_name); err = -EINVAL; goto fail_free; } } sbi->bdi_id = ida_simple_get(&vboxsf_bdi_ida, 0, 0, GFP_KERNEL); if (sbi->bdi_id < 0) { err = sbi->bdi_id; goto fail_free; } err = super_setup_bdi_name(sb, "vboxsf-%d", sbi->bdi_id); if (err) goto fail_free; sb->s_bdi->ra_pages = 0; sb->s_bdi->io_pages = 0; /* Turn source into a shfl_string and map the folder */ size = strlen(fc->source) + 1; folder_name = kmalloc(SHFLSTRING_HEADER_SIZE + size, GFP_KERNEL); if (!folder_name) { err = -ENOMEM; goto fail_free; } folder_name->size = size; folder_name->length = size - 1; strlcpy(folder_name->string.utf8, fc->source, size); err = vboxsf_map_folder(folder_name, &sbi->root); kfree(folder_name); if (err) { vbg_err("vboxsf: Host rejected mount of '%s' with error %d\n", fc->source, err); goto fail_free; } root_path.length = 1; root_path.size = 2; root_path.string.utf8[0] = '/'; root_path.string.utf8[1] = 0; err = vboxsf_stat(sbi, &root_path, &sbi->root_info); if (err) goto fail_unmap; sb->s_magic = VBOXSF_SUPER_MAGIC; sb->s_blocksize = 1024; sb->s_maxbytes = MAX_LFS_FILESIZE; sb->s_op = &vboxsf_super_ops; sb->s_d_op = &vboxsf_dentry_ops; iroot = iget_locked(sb, 0); if (!iroot) { err = -ENOMEM; goto fail_unmap; } vboxsf_init_inode(sbi, iroot, &sbi->root_info, false); unlock_new_inode(iroot); droot = d_make_root(iroot); if (!droot) { err = -ENOMEM; goto fail_unmap; } sb->s_root = droot; sb->s_fs_info = sbi; return 0; fail_unmap: vboxsf_unmap_folder(sbi->root); fail_free: if (sbi->bdi_id >= 0) ida_simple_remove(&vboxsf_bdi_ida, sbi->bdi_id); if (sbi->nls) unload_nls(sbi->nls); idr_destroy(&sbi->ino_idr); kfree(sbi); return err; } static void vboxsf_inode_init_once(void *data) { struct vboxsf_inode *sf_i = data; mutex_init(&sf_i->handle_list_mutex); inode_init_once(&sf_i->vfs_inode); } static struct inode *vboxsf_alloc_inode(struct super_block *sb) { struct vboxsf_inode *sf_i; sf_i = kmem_cache_alloc(vboxsf_inode_cachep, GFP_NOFS); if (!sf_i) return NULL; sf_i->force_restat = 0; INIT_LIST_HEAD(&sf_i->handle_list); return &sf_i->vfs_inode; } static void vboxsf_free_inode(struct inode *inode) { struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb); unsigned long flags; spin_lock_irqsave(&sbi->ino_idr_lock, flags); idr_remove(&sbi->ino_idr, inode->i_ino); spin_unlock_irqrestore(&sbi->ino_idr_lock, flags); kmem_cache_free(vboxsf_inode_cachep, VBOXSF_I(inode)); } static void vboxsf_put_super(struct super_block *sb) { struct vboxsf_sbi *sbi = VBOXSF_SBI(sb); vboxsf_unmap_folder(sbi->root); if (sbi->bdi_id >= 0) ida_simple_remove(&vboxsf_bdi_ida, sbi->bdi_id); if (sbi->nls) unload_nls(sbi->nls); /* * vboxsf_free_inode uses the idr, make sure all delayed rcu free * inodes are flushed. */ rcu_barrier(); idr_destroy(&sbi->ino_idr); kfree(sbi); } static int vboxsf_statfs(struct dentry *dentry, struct kstatfs *stat) { struct super_block *sb = dentry->d_sb; struct shfl_volinfo shfl_volinfo; struct vboxsf_sbi *sbi; u32 buf_len; int err; sbi = VBOXSF_SBI(sb); buf_len = sizeof(shfl_volinfo); err = vboxsf_fsinfo(sbi->root, 0, SHFL_INFO_GET | SHFL_INFO_VOLUME, &buf_len, &shfl_volinfo); if (err) return err; stat->f_type = VBOXSF_SUPER_MAGIC; stat->f_bsize = shfl_volinfo.bytes_per_allocation_unit; do_div(shfl_volinfo.total_allocation_bytes, shfl_volinfo.bytes_per_allocation_unit); stat->f_blocks = shfl_volinfo.total_allocation_bytes; do_div(shfl_volinfo.available_allocation_bytes, shfl_volinfo.bytes_per_allocation_unit); stat->f_bfree = shfl_volinfo.available_allocation_bytes; stat->f_bavail = shfl_volinfo.available_allocation_bytes; stat->f_files = 1000; /* * Don't return 0 here since the guest may then think that it is not * possible to create any more files. */ stat->f_ffree = 1000000; stat->f_fsid.val[0] = 0; stat->f_fsid.val[1] = 0; stat->f_namelen = 255; return 0; } static struct super_operations vboxsf_super_ops = { .alloc_inode = vboxsf_alloc_inode, .free_inode = vboxsf_free_inode, .put_super = vboxsf_put_super, .statfs = vboxsf_statfs, }; static int vboxsf_setup(void) { int err; mutex_lock(&vboxsf_setup_mutex); if (vboxsf_setup_done) goto success; vboxsf_inode_cachep = kmem_cache_create("vboxsf_inode_cache", sizeof(struct vboxsf_inode), 0, (SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD | SLAB_ACCOUNT), vboxsf_inode_init_once); if (!vboxsf_inode_cachep) { err = -ENOMEM; goto fail_nomem; } err = vboxsf_connect(); if (err) { vbg_err("vboxsf: err %d connecting to guest PCI-device\n", err); vbg_err("vboxsf: make sure you are inside a VirtualBox VM\n"); vbg_err("vboxsf: and check dmesg for vboxguest errors\n"); goto fail_free_cache; } err = vboxsf_set_utf8(); if (err) { vbg_err("vboxsf_setutf8 error %d\n", err); goto fail_disconnect; } if (!follow_symlinks) { err = vboxsf_set_symlinks(); if (err) vbg_warn("vboxsf: Unable to show symlinks: %d\n", err); } vboxsf_setup_done = true; success: mutex_unlock(&vboxsf_setup_mutex); return 0; fail_disconnect: vboxsf_disconnect(); fail_free_cache: kmem_cache_destroy(vboxsf_inode_cachep); fail_nomem: mutex_unlock(&vboxsf_setup_mutex); return err; } static int vboxsf_parse_monolithic(struct fs_context *fc, void *data) { unsigned char *options = data; if (options && options[0] == VBSF_MOUNT_SIGNATURE_BYTE_0 && options[1] == VBSF_MOUNT_SIGNATURE_BYTE_1 && options[2] == VBSF_MOUNT_SIGNATURE_BYTE_2 && options[3] == VBSF_MOUNT_SIGNATURE_BYTE_3) { vbg_err("vboxsf: Old binary mount data not supported, remove obsolete mount.vboxsf and/or update your VBoxService.\n"); return -EINVAL; } return generic_parse_monolithic(fc, data); } static int vboxsf_get_tree(struct fs_context *fc) { int err; err = vboxsf_setup(); if (err) return err; return get_tree_nodev(fc, vboxsf_fill_super); } static int vboxsf_reconfigure(struct fs_context *fc) { struct vboxsf_sbi *sbi = VBOXSF_SBI(fc->root->d_sb); struct vboxsf_fs_context *ctx = fc->fs_private; struct inode *iroot = fc->root->d_sb->s_root->d_inode; /* Apply changed options to the root inode */ sbi->o = ctx->o; vboxsf_init_inode(sbi, iroot, &sbi->root_info, true); return 0; } static void vboxsf_free_fc(struct fs_context *fc) { struct vboxsf_fs_context *ctx = fc->fs_private; kfree(ctx->nls_name); kfree(ctx); } static const struct fs_context_operations vboxsf_context_ops = { .free = vboxsf_free_fc, .parse_param = vboxsf_parse_param, .parse_monolithic = vboxsf_parse_monolithic, .get_tree = vboxsf_get_tree, .reconfigure = vboxsf_reconfigure, }; static int vboxsf_init_fs_context(struct fs_context *fc) { struct vboxsf_fs_context *ctx; ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) return -ENOMEM; current_uid_gid(&ctx->o.uid, &ctx->o.gid); fc->fs_private = ctx; fc->ops = &vboxsf_context_ops; return 0; } static struct file_system_type vboxsf_fs_type = { .owner = THIS_MODULE, .name = "vboxsf", .init_fs_context = vboxsf_init_fs_context, .kill_sb = kill_anon_super }; /* Module initialization/finalization handlers */ static int __init vboxsf_init(void) { return register_filesystem(&vboxsf_fs_type); } static void __exit vboxsf_fini(void) { unregister_filesystem(&vboxsf_fs_type); mutex_lock(&vboxsf_setup_mutex); if (vboxsf_setup_done) { vboxsf_disconnect(); /* * Make sure all delayed rcu free inodes are flushed * before we destroy the cache. */ rcu_barrier(); kmem_cache_destroy(vboxsf_inode_cachep); } mutex_unlock(&vboxsf_setup_mutex); } module_init(vboxsf_init); module_exit(vboxsf_fini); MODULE_DESCRIPTION("Oracle VM VirtualBox Module for Host File System Access"); MODULE_AUTHOR("Oracle Corporation"); MODULE_LICENSE("GPL v2"); MODULE_ALIAS_FS("vboxsf");