diff options
Diffstat (limited to 'fs/ecryptfs/file.c')
| -rw-r--r-- | fs/ecryptfs/file.c | 437 |
1 files changed, 437 insertions, 0 deletions
diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c new file mode 100644 index 000000000..b76a98533 --- /dev/null +++ b/fs/ecryptfs/file.c @@ -0,0 +1,437 @@ +/** + * 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> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA + * 02111-1307, USA. + */ + +#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 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, +}; |