/* * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) * Licensed under the GPL * * Ported the filesystem routines to 2.5. * 2003-02-10 Petr Baudis <pasky@ucw.cz> */ #include <linux/stddef.h> #include <linux/fs.h> #include <linux/module.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/pagemap.h> #include <linux/blkdev.h> #include <linux/list.h> #include <linux/statfs.h> #include <linux/kdev_t.h> #include <asm/uaccess.h> #include "hostfs.h" #include "kern_util.h" #include "kern.h" #include "init.h" struct hostfs_inode_info { char *host_filename; int fd; int mode; struct inode vfs_inode; }; static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) { return list_entry(inode, struct hostfs_inode_info, vfs_inode); } #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode) int hostfs_d_delete(struct dentry *dentry) { return 1; } struct dentry_operations hostfs_dentry_ops = { .d_delete = hostfs_d_delete, }; /* Changed in hostfs_args before the kernel starts running */ static char *root_ino = ""; static int append = 0; #define HOSTFS_SUPER_MAGIC 0x00c0ffee static const struct inode_operations hostfs_iops; static const struct inode_operations hostfs_dir_iops; static const struct address_space_operations hostfs_link_aops; #ifndef MODULE static int __init hostfs_args(char *options, int *add) { char *ptr; ptr = strchr(options, ','); if(ptr != NULL) *ptr++ = '\0'; if(*options != '\0') root_ino = options; options = ptr; while(options){ ptr = strchr(options, ','); if(ptr != NULL) *ptr++ = '\0'; if(*options != '\0'){ if(!strcmp(options, "append")) append = 1; else printf("hostfs_args - unsupported option - %s\n", options); } options = ptr; } return 0; } __uml_setup("hostfs=", hostfs_args, "hostfs=<root dir>,<flags>,...\n" " This is used to set hostfs parameters. The root directory argument\n" " is used to confine all hostfs mounts to within the specified directory\n" " tree on the host. If this isn't specified, then a user inside UML can\n" " mount anything on the host that's accessible to the user that's running\n" " it.\n" " The only flag currently supported is 'append', which specifies that all\n" " files opened by hostfs will be opened in append mode.\n\n" ); #endif static char *dentry_name(struct dentry *dentry, int extra) { struct dentry *parent; char *root, *name; int len; len = 0; parent = dentry; while(parent->d_parent != parent){ len += parent->d_name.len + 1; parent = parent->d_parent; } root = HOSTFS_I(parent->d_inode)->host_filename; len += strlen(root); name = kmalloc(len + extra + 1, GFP_KERNEL); if(name == NULL) return NULL; name[len] = '\0'; parent = dentry; while(parent->d_parent != parent){ len -= parent->d_name.len + 1; name[len] = '/'; strncpy(&name[len + 1], parent->d_name.name, parent->d_name.len); parent = parent->d_parent; } strncpy(name, root, strlen(root)); return name; } static char *inode_name(struct inode *ino, int extra) { struct dentry *dentry; dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias); return dentry_name(dentry, extra); } static int read_name(struct inode *ino, char *name) { /* The non-int inode fields are copied into ints by stat_file and * then copied into the inode because passing the actual pointers * in and having them treated as int * breaks on big-endian machines */ int err; int i_mode, i_nlink, i_blksize; unsigned long long i_size; unsigned long long i_ino; unsigned long long i_blocks; err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid, &ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime, &ino->i_ctime, &i_blksize, &i_blocks, -1); if(err) return err; ino->i_ino = i_ino; ino->i_mode = i_mode; ino->i_nlink = i_nlink; ino->i_size = i_size; ino->i_blocks = i_blocks; return 0; } static char *follow_link(char *link) { int len, n; char *name, *resolved, *end; len = 64; while(1){ n = -ENOMEM; name = kmalloc(len, GFP_KERNEL); if(name == NULL) goto out; n = do_readlink(link, name, len); if(n < len) break; len *= 2; kfree(name); } if(n < 0) goto out_free; if(*name == '/') return name; end = strrchr(link, '/'); if(end == NULL) return name; *(end + 1) = '\0'; len = strlen(link) + strlen(name) + 1; resolved = kmalloc(len, GFP_KERNEL); if(resolved == NULL){ n = -ENOMEM; goto out_free; } sprintf(resolved, "%s%s", link, name); kfree(name); kfree(link); return resolved; out_free: kfree(name); out: return ERR_PTR(n); } static int read_inode(struct inode *ino) { char *name; int err = 0; /* Unfortunately, we are called from iget() when we don't have a dentry * allocated yet. */ if(list_empty(&ino->i_dentry)) goto out; err = -ENOMEM; name = inode_name(ino, 0); if(name == NULL) goto out; if(file_type(name, NULL, NULL) == OS_TYPE_SYMLINK){ name = follow_link(name); if(IS_ERR(name)){ err = PTR_ERR(name); goto out; } } err = read_name(ino, name); kfree(name); out: return err; } int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) { /* do_statfs uses struct statfs64 internally, but the linux kernel * struct statfs still has 32-bit versions for most of these fields, * so we convert them here */ int err; long long f_blocks; long long f_bfree; long long f_bavail; long long f_files; long long f_ffree; err = do_statfs(HOSTFS_I(dentry->d_sb->s_root->d_inode)->host_filename, &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), &sf->f_namelen, sf->f_spare); if(err) return err; sf->f_blocks = f_blocks; sf->f_bfree = f_bfree; sf->f_bavail = f_bavail; sf->f_files = f_files; sf->f_ffree = f_ffree; sf->f_type = HOSTFS_SUPER_MAGIC; return 0; } static struct inode *hostfs_alloc_inode(struct super_block *sb) { struct hostfs_inode_info *hi; hi = kmalloc(sizeof(*hi), GFP_KERNEL); if(hi == NULL) return NULL; *hi = ((struct hostfs_inode_info) { .host_filename = NULL, .fd = -1, .mode = 0 }); inode_init_once(&hi->vfs_inode); return &hi->vfs_inode; } static void hostfs_delete_inode(struct inode *inode) { truncate_inode_pages(&inode->i_data, 0); if(HOSTFS_I(inode)->fd != -1) { close_file(&HOSTFS_I(inode)->fd); HOSTFS_I(inode)->fd = -1; } clear_inode(inode); } static void hostfs_destroy_inode(struct inode *inode) { kfree(HOSTFS_I(inode)->host_filename); /*XXX: This should not happen, probably. The check is here for * additional safety.*/ if(HOSTFS_I(inode)->fd != -1) { close_file(&HOSTFS_I(inode)->fd); printk(KERN_DEBUG "Closing host fd in .destroy_inode\n"); } kfree(HOSTFS_I(inode)); } static void hostfs_read_inode(struct inode *inode) { read_inode(inode); } static const struct super_operations hostfs_sbops = { .alloc_inode = hostfs_alloc_inode, .drop_inode = generic_delete_inode, .delete_inode = hostfs_delete_inode, .destroy_inode = hostfs_destroy_inode, .read_inode = hostfs_read_inode, .statfs = hostfs_statfs, }; int hostfs_readdir(struct file *file, void *ent, filldir_t filldir) { void *dir; char *name; unsigned long long next, ino; int error, len; name = dentry_name(file->f_path.dentry, 0); if(name == NULL) return -ENOMEM; dir = open_dir(name, &error); kfree(name); if(dir == NULL) return -error; next = file->f_pos; while((name = read_dir(dir, &next, &ino, &len)) != NULL){ error = (*filldir)(ent, name, len, file->f_pos, ino, DT_UNKNOWN); if(error) break; file->f_pos = next; } close_dir(dir); return 0; } int hostfs_file_open(struct inode *ino, struct file *file) { char *name; int mode = 0, r = 0, w = 0, fd; mode = file->f_mode & (FMODE_READ | FMODE_WRITE); if((mode & HOSTFS_I(ino)->mode) == mode) return 0; /* The file may already have been opened, but with the wrong access, * so this resets things and reopens the file with the new access. */ if(HOSTFS_I(ino)->fd != -1){ close_file(&HOSTFS_I(ino)->fd); HOSTFS_I(ino)->fd = -1; } HOSTFS_I(ino)->mode |= mode; if(HOSTFS_I(ino)->mode & FMODE_READ) r = 1; if(HOSTFS_I(ino)->mode & FMODE_WRITE) w = 1; if(w) r = 1; name = dentry_name(file->f_path.dentry, 0); if(name == NULL) return -ENOMEM; fd = open_file(name, r, w, append); kfree(name); if(fd < 0) return fd; FILE_HOSTFS_I(file)->fd = fd; return 0; } int hostfs_fsync(struct file *file, struct dentry *dentry, int datasync) { return fsync_file(HOSTFS_I(dentry->d_inode)->fd, datasync); } static const struct file_operations hostfs_file_fops = { .llseek = generic_file_llseek, .read = do_sync_read, .sendfile = generic_file_sendfile, .aio_read = generic_file_aio_read, .aio_write = generic_file_aio_write, .write = do_sync_write, .mmap = generic_file_mmap, .open = hostfs_file_open, .release = NULL, .fsync = hostfs_fsync, }; static const struct file_operations hostfs_dir_fops = { .llseek = generic_file_llseek, .readdir = hostfs_readdir, .read = generic_read_dir, }; int hostfs_writepage(struct page *page, struct writeback_control *wbc) { struct address_space *mapping = page->mapping; struct inode *inode = mapping->host; char *buffer; unsigned long long base; int count = PAGE_CACHE_SIZE; int end_index = inode->i_size >> PAGE_CACHE_SHIFT; int err; if (page->index >= end_index) count = inode->i_size & (PAGE_CACHE_SIZE-1); buffer = kmap(page); base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT; err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); if(err != count){ ClearPageUptodate(page); goto out; } if (base > inode->i_size) inode->i_size = base; if (PageError(page)) ClearPageError(page); err = 0; out: kunmap(page); unlock_page(page); return err; } int hostfs_readpage(struct file *file, struct page *page) { char *buffer; long long start; int err = 0; start = (long long) page->index << PAGE_CACHE_SHIFT; buffer = kmap(page); err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, PAGE_CACHE_SIZE); if(err < 0) goto out; memset(&buffer[err], 0, PAGE_CACHE_SIZE - err); flush_dcache_page(page); SetPageUptodate(page); if (PageError(page)) ClearPageError(page); err = 0; out: kunmap(page); unlock_page(page); return err; } int hostfs_prepare_write(struct file *file, struct page *page, unsigned int from, unsigned int to) { char *buffer; long long start, tmp; int err; start = (long long) page->index << PAGE_CACHE_SHIFT; buffer = kmap(page); if(from != 0){ tmp = start; err = read_file(FILE_HOSTFS_I(file)->fd, &tmp, buffer, from); if(err < 0) goto out; } if(to != PAGE_CACHE_SIZE){ start += to; err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer + to, PAGE_CACHE_SIZE - to); if(err < 0) goto out; } err = 0; out: kunmap(page); return err; } int hostfs_commit_write(struct file *file, struct page *page, unsigned from, unsigned to) { struct address_space *mapping = page->mapping; struct inode *inode = mapping->host; char *buffer; long long start; int err = 0; start = (((long long) page->index) << PAGE_CACHE_SHIFT) + from; buffer = kmap(page); err = write_file(FILE_HOSTFS_I(file)->fd, &start, buffer + from, to - from); if(err > 0) err = 0; /* Actually, if !err, write_file has added to-from to start, so, despite * the appearance, we are comparing i_size against the _last_ written * location, as we should. */ if(!err && (start > inode->i_size)) inode->i_size = start; kunmap(page); return err; } static const struct address_space_operations hostfs_aops = { .writepage = hostfs_writepage, .readpage = hostfs_readpage, .set_page_dirty = __set_page_dirty_nobuffers, .prepare_write = hostfs_prepare_write, .commit_write = hostfs_commit_write }; static int init_inode(struct inode *inode, struct dentry *dentry) { char *name; int type, err = -ENOMEM; int maj, min; dev_t rdev = 0; if(dentry){ name = dentry_name(dentry, 0); if(name == NULL) goto out; type = file_type(name, &maj, &min); /*Reencode maj and min with the kernel encoding.*/ rdev = MKDEV(maj, min); kfree(name); } else type = OS_TYPE_DIR; err = 0; if(type == OS_TYPE_SYMLINK) inode->i_op = &page_symlink_inode_operations; else if(type == OS_TYPE_DIR) inode->i_op = &hostfs_dir_iops; else inode->i_op = &hostfs_iops; if(type == OS_TYPE_DIR) inode->i_fop = &hostfs_dir_fops; else inode->i_fop = &hostfs_file_fops; if(type == OS_TYPE_SYMLINK) inode->i_mapping->a_ops = &hostfs_link_aops; else inode->i_mapping->a_ops = &hostfs_aops; switch (type) { case OS_TYPE_CHARDEV: init_special_inode(inode, S_IFCHR, rdev); break; case OS_TYPE_BLOCKDEV: init_special_inode(inode, S_IFBLK, rdev); break; case OS_TYPE_FIFO: init_special_inode(inode, S_IFIFO, 0); break; case OS_TYPE_SOCK: init_special_inode(inode, S_IFSOCK, 0); break; } out: return err; } int hostfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd) { struct inode *inode; char *name; int error, fd; error = -ENOMEM; inode = iget(dir->i_sb, 0); if(inode == NULL) goto out; error = init_inode(inode, dentry); if(error) goto out_put; error = -ENOMEM; name = dentry_name(dentry, 0); if(name == NULL) goto out_put; fd = file_create(name, mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR, mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP, mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH); if(fd < 0) error = fd; else error = read_name(inode, name); kfree(name); if(error) goto out_put; HOSTFS_I(inode)->fd = fd; HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; d_instantiate(dentry, inode); return 0; out_put: iput(inode); out: return error; } struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, struct nameidata *nd) { struct inode *inode; char *name; int err; err = -ENOMEM; inode = iget(ino->i_sb, 0); if(inode == NULL) goto out; err = init_inode(inode, dentry); if(err) goto out_put; err = -ENOMEM; name = dentry_name(dentry, 0); if(name == NULL) goto out_put; err = read_name(inode, name); kfree(name); if(err == -ENOENT){ iput(inode); inode = NULL; } else if(err) goto out_put; d_add(dentry, inode); dentry->d_op = &hostfs_dentry_ops; return NULL; out_put: iput(inode); out: return ERR_PTR(err); } static char *inode_dentry_name(struct inode *ino, struct dentry *dentry) { char *file; int len; file = inode_name(ino, dentry->d_name.len + 1); if(file == NULL) return NULL; strcat(file, "/"); len = strlen(file); strncat(file, dentry->d_name.name, dentry->d_name.len); file[len + dentry->d_name.len] = '\0'; return file; } int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from) { char *from_name, *to_name; int err; if((from_name = inode_dentry_name(ino, from)) == NULL) return -ENOMEM; to_name = dentry_name(to, 0); if(to_name == NULL){ kfree(from_name); return -ENOMEM; } err = link_file(to_name, from_name); kfree(from_name); kfree(to_name); return err; } int hostfs_unlink(struct inode *ino, struct dentry *dentry) { char *file; int err; if((file = inode_dentry_name(ino, dentry)) == NULL) return -ENOMEM; if(append) return -EPERM; err = unlink_file(file); kfree(file); return err; } int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to) { char *file; int err; if((file = inode_dentry_name(ino, dentry)) == NULL) return -ENOMEM; err = make_symlink(file, to); kfree(file); return err; } int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode) { char *file; int err; if((file = inode_dentry_name(ino, dentry)) == NULL) return -ENOMEM; err = do_mkdir(file, mode); kfree(file); return err; } int hostfs_rmdir(struct inode *ino, struct dentry *dentry) { char *file; int err; if((file = inode_dentry_name(ino, dentry)) == NULL) return -ENOMEM; err = do_rmdir(file); kfree(file); return err; } int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) { struct inode *inode; char *name; int err = -ENOMEM; inode = iget(dir->i_sb, 0); if(inode == NULL) goto out; err = init_inode(inode, dentry); if(err) goto out_put; err = -ENOMEM; name = dentry_name(dentry, 0); if(name == NULL) goto out_put; init_special_inode(inode, mode, dev); err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); if(err) goto out_free; err = read_name(inode, name); kfree(name); if(err) goto out_put; d_instantiate(dentry, inode); return 0; out_free: kfree(name); out_put: iput(inode); out: return err; } int hostfs_rename(struct inode *from_ino, struct dentry *from, struct inode *to_ino, struct dentry *to) { char *from_name, *to_name; int err; if((from_name = inode_dentry_name(from_ino, from)) == NULL) return -ENOMEM; if((to_name = inode_dentry_name(to_ino, to)) == NULL){ kfree(from_name); return -ENOMEM; } err = rename_file(from_name, to_name); kfree(from_name); kfree(to_name); return err; } int hostfs_permission(struct inode *ino, int desired, struct nameidata *nd) { char *name; int r = 0, w = 0, x = 0, err; if (desired & MAY_READ) r = 1; if (desired & MAY_WRITE) w = 1; if (desired & MAY_EXEC) x = 1; name = inode_name(ino, 0); if (name == NULL) return -ENOMEM; if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) err = 0; else err = access_file(name, r, w, x); kfree(name); if(!err) err = generic_permission(ino, desired, NULL); return err; } int hostfs_setattr(struct dentry *dentry, struct iattr *attr) { struct hostfs_iattr attrs; char *name; int err; int fd = HOSTFS_I(dentry->d_inode)->fd; err = inode_change_ok(dentry->d_inode, attr); if (err) return err; if(append) attr->ia_valid &= ~ATTR_SIZE; attrs.ia_valid = 0; if(attr->ia_valid & ATTR_MODE){ attrs.ia_valid |= HOSTFS_ATTR_MODE; attrs.ia_mode = attr->ia_mode; } if(attr->ia_valid & ATTR_UID){ attrs.ia_valid |= HOSTFS_ATTR_UID; attrs.ia_uid = attr->ia_uid; } if(attr->ia_valid & ATTR_GID){ attrs.ia_valid |= HOSTFS_ATTR_GID; attrs.ia_gid = attr->ia_gid; } if(attr->ia_valid & ATTR_SIZE){ attrs.ia_valid |= HOSTFS_ATTR_SIZE; attrs.ia_size = attr->ia_size; } if(attr->ia_valid & ATTR_ATIME){ attrs.ia_valid |= HOSTFS_ATTR_ATIME; attrs.ia_atime = attr->ia_atime; } if(attr->ia_valid & ATTR_MTIME){ attrs.ia_valid |= HOSTFS_ATTR_MTIME; attrs.ia_mtime = attr->ia_mtime; } if(attr->ia_valid & ATTR_CTIME){ attrs.ia_valid |= HOSTFS_ATTR_CTIME; attrs.ia_ctime = attr->ia_ctime; } if(attr->ia_valid & ATTR_ATIME_SET){ attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; } if(attr->ia_valid & ATTR_MTIME_SET){ attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; } name = dentry_name(dentry, 0); if(name == NULL) return -ENOMEM; err = set_attr(name, &attrs, fd); kfree(name); if(err) return err; return inode_setattr(dentry->d_inode, attr); } int hostfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) { generic_fillattr(dentry->d_inode, stat); return 0; } static const struct inode_operations hostfs_iops = { .create = hostfs_create, .link = hostfs_link, .unlink = hostfs_unlink, .symlink = hostfs_symlink, .mkdir = hostfs_mkdir, .rmdir = hostfs_rmdir, .mknod = hostfs_mknod, .rename = hostfs_rename, .permission = hostfs_permission, .setattr = hostfs_setattr, .getattr = hostfs_getattr, }; static const struct inode_operations hostfs_dir_iops = { .create = hostfs_create, .lookup = hostfs_lookup, .link = hostfs_link, .unlink = hostfs_unlink, .symlink = hostfs_symlink, .mkdir = hostfs_mkdir, .rmdir = hostfs_rmdir, .mknod = hostfs_mknod, .rename = hostfs_rename, .permission = hostfs_permission, .setattr = hostfs_setattr, .getattr = hostfs_getattr, }; int hostfs_link_readpage(struct file *file, struct page *page) { char *buffer, *name; int err; buffer = kmap(page); name = inode_name(page->mapping->host, 0); if(name == NULL) return -ENOMEM; err = do_readlink(name, buffer, PAGE_CACHE_SIZE); kfree(name); if(err == PAGE_CACHE_SIZE) err = -E2BIG; else if(err > 0){ flush_dcache_page(page); SetPageUptodate(page); if (PageError(page)) ClearPageError(page); err = 0; } kunmap(page); unlock_page(page); return err; } static const struct address_space_operations hostfs_link_aops = { .readpage = hostfs_link_readpage, }; static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) { struct inode *root_inode; char *host_root_path, *req_root = d; int err; sb->s_blocksize = 1024; sb->s_blocksize_bits = 10; sb->s_magic = HOSTFS_SUPER_MAGIC; sb->s_op = &hostfs_sbops; /* NULL is printed as <NULL> by sprintf: avoid that. */ if (req_root == NULL) req_root = ""; err = -ENOMEM; host_root_path = kmalloc(strlen(root_ino) + 1 + strlen(req_root) + 1, GFP_KERNEL); if(host_root_path == NULL) goto out; sprintf(host_root_path, "%s/%s", root_ino, req_root); root_inode = iget(sb, 0); if(root_inode == NULL) goto out_free; err = init_inode(root_inode, NULL); if(err) goto out_put; HOSTFS_I(root_inode)->host_filename = host_root_path; /* Avoid that in the error path, iput(root_inode) frees again * host_root_path through hostfs_destroy_inode! */ host_root_path = NULL; err = -ENOMEM; sb->s_root = d_alloc_root(root_inode); if(sb->s_root == NULL) goto out_put; err = read_inode(root_inode); if(err){ /* No iput in this case because the dput does that for us */ dput(sb->s_root); sb->s_root = NULL; goto out; } return 0; out_put: iput(root_inode); out_free: kfree(host_root_path); out: return err; } static int hostfs_read_sb(struct file_system_type *type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { return get_sb_nodev(type, flags, data, hostfs_fill_sb_common, mnt); } static struct file_system_type hostfs_type = { .owner = THIS_MODULE, .name = "hostfs", .get_sb = hostfs_read_sb, .kill_sb = kill_anon_super, .fs_flags = 0, }; static int __init init_hostfs(void) { return register_filesystem(&hostfs_type); } static void __exit exit_hostfs(void) { unregister_filesystem(&hostfs_type); } module_init(init_hostfs) module_exit(exit_hostfs) MODULE_LICENSE("GPL");