// SPDX-License-Identifier: GPL-2.0-or-later /* * eCryptfs: Linux filesystem encryption layer * * Copyright (C) 1997-2004 Erez Zadok * Copyright (C) 2001-2004 Stony Brook University * Copyright (C) 2004-2007 International Business Machines Corp. * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com> * Michael C. Thompson <mcthomps@us.ibm.com> */ #include <linux/file.h> #include <linux/poll.h> #include <linux/slab.h> #include <linux/mount.h> #include <linux/pagemap.h> #include <linux/security.h> #include <linux/compat.h> #include <linux/fs_stack.h> #include "ecryptfs_kernel.h" /* * ecryptfs_read_update_atime * * generic_file_read updates the atime of upper layer inode. But, it * doesn't give us a chance to update the atime of the lower layer * inode. This function is a wrapper to generic_file_read. It * updates the atime of the lower level inode if generic_file_read * returns without any errors. This is to be used only for file reads. * The function to be used for directory reads is ecryptfs_read. */ static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb, struct iov_iter *to) { ssize_t rc; struct path *path; struct file *file = iocb->ki_filp; rc = generic_file_read_iter(iocb, to); if (rc >= 0) { path = ecryptfs_dentry_to_lower_path(file->f_path.dentry); touch_atime(path); } return rc; } struct ecryptfs_getdents_callback { struct dir_context ctx; struct dir_context *caller; struct super_block *sb; int filldir_called; int entries_written; }; /* Inspired by generic filldir in fs/readdir.c */ static int ecryptfs_filldir(struct dir_context *ctx, const char *lower_name, int lower_namelen, loff_t offset, u64 ino, unsigned int d_type) { struct ecryptfs_getdents_callback *buf = container_of(ctx, struct ecryptfs_getdents_callback, ctx); size_t name_size; char *name; int rc; buf->filldir_called++; rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size, buf->sb, lower_name, lower_namelen); if (rc) { if (rc != -EINVAL) { ecryptfs_printk(KERN_DEBUG, "%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n", __func__, lower_name, rc); return rc; } /* Mask -EINVAL errors as these are most likely due a plaintext * filename present in the lower filesystem despite filename * encryption being enabled. One unavoidable example would be * the "lost+found" dentry in the root directory of an Ext4 * filesystem. */ return 0; } buf->caller->pos = buf->ctx.pos; rc = !dir_emit(buf->caller, name, name_size, ino, d_type); kfree(name); if (!rc) buf->entries_written++; return rc; } /** * ecryptfs_readdir * @file: The eCryptfs directory file * @ctx: The actor to feed the entries to */ static int ecryptfs_readdir(struct file *file, struct dir_context *ctx) { int rc; struct file *lower_file; struct inode *inode = file_inode(file); struct ecryptfs_getdents_callback buf = { .ctx.actor = ecryptfs_filldir, .caller = ctx, .sb = inode->i_sb, }; lower_file = ecryptfs_file_to_lower(file); rc = iterate_dir(lower_file, &buf.ctx); ctx->pos = buf.ctx.pos; if (rc < 0) goto out; if (buf.filldir_called && !buf.entries_written) goto out; if (rc >= 0) fsstack_copy_attr_atime(inode, file_inode(lower_file)); out: return rc; } struct kmem_cache *ecryptfs_file_info_cache; static int read_or_initialize_metadata(struct dentry *dentry) { struct inode *inode = d_inode(dentry); struct ecryptfs_mount_crypt_stat *mount_crypt_stat; struct ecryptfs_crypt_stat *crypt_stat; int rc; crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; mount_crypt_stat = &ecryptfs_superblock_to_private( inode->i_sb)->mount_crypt_stat; mutex_lock(&crypt_stat->cs_mutex); if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED && crypt_stat->flags & ECRYPTFS_KEY_VALID) { rc = 0; goto out; } rc = ecryptfs_read_metadata(dentry); if (!rc) goto out; if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) { crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED | ECRYPTFS_ENCRYPTED); rc = 0; goto out; } if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) && !i_size_read(ecryptfs_inode_to_lower(inode))) { rc = ecryptfs_initialize_file(dentry, inode); if (!rc) goto out; } rc = -EIO; out: mutex_unlock(&crypt_stat->cs_mutex); return rc; } static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma) { struct file *lower_file = ecryptfs_file_to_lower(file); /* * Don't allow mmap on top of file systems that don't support it * natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs * allows recursive mounting, this will need to be extended. */ if (!lower_file->f_op->mmap) return -ENODEV; return generic_file_mmap(file, vma); } /** * ecryptfs_open * @inode: inode specifying file to open * @file: Structure to return filled in * * Opens the file specified by inode. * * Returns zero on success; non-zero otherwise */ static int ecryptfs_open(struct inode *inode, struct file *file) { int rc = 0; struct ecryptfs_crypt_stat *crypt_stat = NULL; struct dentry *ecryptfs_dentry = file->f_path.dentry; /* Private value of ecryptfs_dentry allocated in * ecryptfs_lookup() */ struct ecryptfs_file_info *file_info; /* Released in ecryptfs_release or end of function if failure */ file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); ecryptfs_set_file_private(file, file_info); if (!file_info) { ecryptfs_printk(KERN_ERR, "Error attempting to allocate memory\n"); rc = -ENOMEM; goto out; } crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; mutex_lock(&crypt_stat->cs_mutex); if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); /* Policy code enabled in future release */ crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED | ECRYPTFS_ENCRYPTED); } mutex_unlock(&crypt_stat->cs_mutex); rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode); if (rc) { printk(KERN_ERR "%s: Error attempting to initialize " "the lower file for the dentry with name " "[%pd]; rc = [%d]\n", __func__, ecryptfs_dentry, rc); goto out_free; } if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { rc = -EPERM; printk(KERN_WARNING "%s: Lower file is RO; eCryptfs " "file must hence be opened RO\n", __func__); goto out_put; } ecryptfs_set_file_lower( file, ecryptfs_inode_to_private(inode)->lower_file); rc = read_or_initialize_metadata(ecryptfs_dentry); if (rc) goto out_put; ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = " "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino, (unsigned long long)i_size_read(inode)); goto out; out_put: ecryptfs_put_lower_file(inode); out_free: kmem_cache_free(ecryptfs_file_info_cache, ecryptfs_file_to_private(file)); out: return rc; } /** * ecryptfs_dir_open * @inode: inode specifying file to open * @file: Structure to return filled in * * Opens the file specified by inode. * * Returns zero on success; non-zero otherwise */ static int ecryptfs_dir_open(struct inode *inode, struct file *file) { struct dentry *ecryptfs_dentry = file->f_path.dentry; /* Private value of ecryptfs_dentry allocated in * ecryptfs_lookup() */ struct ecryptfs_file_info *file_info; struct file *lower_file; /* Released in ecryptfs_release or end of function if failure */ file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); ecryptfs_set_file_private(file, file_info); if (unlikely(!file_info)) { ecryptfs_printk(KERN_ERR, "Error attempting to allocate memory\n"); return -ENOMEM; } lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry), file->f_flags, current_cred()); if (IS_ERR(lower_file)) { printk(KERN_ERR "%s: Error attempting to initialize " "the lower file for the dentry with name " "[%pd]; rc = [%ld]\n", __func__, ecryptfs_dentry, PTR_ERR(lower_file)); kmem_cache_free(ecryptfs_file_info_cache, file_info); return PTR_ERR(lower_file); } ecryptfs_set_file_lower(file, lower_file); return 0; } static int ecryptfs_flush(struct file *file, fl_owner_t td) { struct file *lower_file = ecryptfs_file_to_lower(file); if (lower_file->f_op->flush) { filemap_write_and_wait(file->f_mapping); return lower_file->f_op->flush(lower_file, td); } return 0; } static int ecryptfs_release(struct inode *inode, struct file *file) { ecryptfs_put_lower_file(inode); kmem_cache_free(ecryptfs_file_info_cache, ecryptfs_file_to_private(file)); return 0; } static int ecryptfs_dir_release(struct inode *inode, struct file *file) { fput(ecryptfs_file_to_lower(file)); kmem_cache_free(ecryptfs_file_info_cache, ecryptfs_file_to_private(file)); return 0; } static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence) { return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence); } static int ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) { int rc; rc = file_write_and_wait(file); if (rc) return rc; return vfs_fsync(ecryptfs_file_to_lower(file), datasync); } static int ecryptfs_fasync(int fd, struct file *file, int flag) { int rc = 0; struct file *lower_file = NULL; lower_file = ecryptfs_file_to_lower(file); if (lower_file->f_op->fasync) rc = lower_file->f_op->fasync(fd, lower_file, flag); return rc; } static long ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct file *lower_file = ecryptfs_file_to_lower(file); long rc = -ENOTTY; if (!lower_file->f_op->unlocked_ioctl) return rc; switch (cmd) { case FITRIM: case FS_IOC_GETFLAGS: case FS_IOC_SETFLAGS: case FS_IOC_GETVERSION: case FS_IOC_SETVERSION: rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); fsstack_copy_attr_all(file_inode(file), file_inode(lower_file)); return rc; default: return rc; } } #ifdef CONFIG_COMPAT static long ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct file *lower_file = ecryptfs_file_to_lower(file); long rc = -ENOIOCTLCMD; if (!lower_file->f_op->compat_ioctl) return rc; switch (cmd) { case FITRIM: case FS_IOC32_GETFLAGS: case FS_IOC32_SETFLAGS: case FS_IOC32_GETVERSION: case FS_IOC32_SETVERSION: rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); fsstack_copy_attr_all(file_inode(file), file_inode(lower_file)); return rc; default: return rc; } } #endif const struct file_operations ecryptfs_dir_fops = { .iterate_shared = ecryptfs_readdir, .read = generic_read_dir, .unlocked_ioctl = ecryptfs_unlocked_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = ecryptfs_compat_ioctl, #endif .open = ecryptfs_dir_open, .release = ecryptfs_dir_release, .fsync = ecryptfs_fsync, .llseek = ecryptfs_dir_llseek, }; const struct file_operations ecryptfs_main_fops = { .llseek = generic_file_llseek, .read_iter = ecryptfs_read_update_atime, .write_iter = generic_file_write_iter, .unlocked_ioctl = ecryptfs_unlocked_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = ecryptfs_compat_ioctl, #endif .mmap = ecryptfs_mmap, .open = ecryptfs_open, .flush = ecryptfs_flush, .release = ecryptfs_release, .fsync = ecryptfs_fsync, .fasync = ecryptfs_fasync, .splice_read = generic_file_splice_read, };