main.c

linux 内核源代码

/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 1997-2003 Erez Zadok
 * Copyright (C) 2001-2003 Stony Brook University
 * Copyright (C) 2004-2007 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <[e-mail]>
 *              Michael C. Thompson <[e-mail]>
 *              Tyler Hicks <[e-mail]>
 *
 * 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/dcache.h>
#include <linux/file.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/skbuff.h>
#include <linux/crypto.h>
#include <linux/netlink.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/key.h>
#include <linux/parser.h>
#include <linux/fs_stack.h>
#include "ecryptfs_kernel.h"

/**
 * Module parameter that defines the ecryptfs_verbosity level.
 */
int ecryptfs_verbosity = 0;

module_param(ecryptfs_verbosity, int, 0);
MODULE_PARM_DESC(ecryptfs_verbosity,
		 "Initial verbosity level (0 or 1; defaults to "
		 "0, which is Quiet)");

/**
 * Module parameter that defines the number of netlink message buffer
 * elements
 */
unsigned int ecryptfs_message_buf_len = ECRYPTFS_DEFAULT_MSG_CTX_ELEMS;

module_param(ecryptfs_message_buf_len, uint, 0);
MODULE_PARM_DESC(ecryptfs_message_buf_len,
		 "Number of message buffer elements");

/**
 * Module parameter that defines the maximum guaranteed amount of time to wait
 * for a response through netlink.  The actual sleep time will be, more than
 * likely, a small amount greater than this specified value, but only less if
 * the netlink message successfully arrives.
 */
signed long ecryptfs_message_wait_timeout = ECRYPTFS_MAX_MSG_CTX_TTL / HZ;

module_param(ecryptfs_message_wait_timeout, long, 0);
MODULE_PARM_DESC(ecryptfs_message_wait_timeout,
		 "Maximum number of seconds that an operation will "
		 "sleep while waiting for a message response from "
		 "userspace");

/**
 * Module parameter that is an estimate of the maximum number of users
 * that will be concurrently using eCryptfs. Set this to the right
 * value to balance performance and memory use.
 */
unsigned int ecryptfs_number_of_users = ECRYPTFS_DEFAULT_NUM_USERS;

module_param(ecryptfs_number_of_users, uint, 0);
MODULE_PARM_DESC(ecryptfs_number_of_users, "An estimate of the number of "
		 "concurrent users of eCryptfs");

unsigned int ecryptfs_transport = ECRYPTFS_DEFAULT_TRANSPORT;

void __ecryptfs_printk(const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	if (fmt[1] == '7') { /* KERN_DEBUG */
		if (ecryptfs_verbosity >= 1)
			vprintk(fmt, args);
	} else
		vprintk(fmt, args);
	va_end(args);
}

/**
 * ecryptfs_init_persistent_file
 * @ecryptfs_dentry: Fully initialized eCryptfs dentry object, with
 *                   the lower dentry and the lower mount set
 *
 * eCryptfs only ever keeps a single open file for every lower
 * inode. All I/O operations to the lower inode occur through that
 * file. When the first eCryptfs dentry that interposes with the first
 * lower dentry for that inode is created, this function creates the
 * persistent file struct and associates it with the eCryptfs
 * inode. When the eCryptfs inode is destroyed, the file is closed.
 *
 * The persistent file will be opened with read/write permissions, if
 * possible. Otherwise, it is opened read-only.
 *
 * This function does nothing if a lower persistent file is already
 * associated with the eCryptfs inode.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
{
	struct ecryptfs_inode_info *inode_info =
		ecryptfs_inode_to_private(ecryptfs_dentry->d_inode);
	int rc = 0;

	mutex_lock(&inode_info->lower_file_mutex);
	if (!inode_info->lower_file) {
		struct dentry *lower_dentry;
		struct vfsmount *lower_mnt =
			ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);

		lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
		/* Corresponding dput() and mntput() are done when the
		 * persistent file is fput() when the eCryptfs inode
		 * is destroyed. */
		dget(lower_dentry);
		mntget(lower_mnt);
		inode_info->lower_file = dentry_open(lower_dentry,
						     lower_mnt,
						     (O_RDWR | O_LARGEFILE));
		if (IS_ERR(inode_info->lower_file)) {
			dget(lower_dentry);
			mntget(lower_mnt);
			inode_info->lower_file = dentry_open(lower_dentry,
							     lower_mnt,
							     (O_RDONLY
							      | O_LARGEFILE));
		}
		if (IS_ERR(inode_info->lower_file)) {
			printk(KERN_ERR "Error opening lower persistent file "
			       "for lower_dentry [0x%p] and lower_mnt [0x%p]\n",
			       lower_dentry, lower_mnt);
			rc = PTR_ERR(inode_info->lower_file);
			inode_info->lower_file = NULL;
		}
	}
	mutex_unlock(&inode_info->lower_file_mutex);
	return rc;
}

/**
 * ecryptfs_interpose
 * @lower_dentry: Existing dentry in the lower filesystem
 * @dentry: ecryptfs' dentry
 * @sb: ecryptfs's super_block
 * @flag: If set to true, then d_add is called, else d_instantiate is called
 *
 * Interposes upper and lower dentries.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_interpose(struct dentry *lower_dentry, struct dentry *dentry,
		       struct super_block *sb, int flag)
{
	struct inode *lower_inode;
	struct inode *inode;
	int rc = 0;

	lower_inode = lower_dentry->d_inode;
	if (lower_inode->i_sb != ecryptfs_superblock_to_lower(sb)) {
		rc = -EXDEV;
		goto out;
	}
	if (!igrab(lower_inode)) {
		rc = -ESTALE;
		goto out;
	}
	inode = iget5_locked(sb, (unsigned long)lower_inode,
			     ecryptfs_inode_test, ecryptfs_inode_set,
			     lower_inode);
	if (!inode) {
		rc = -EACCES;
		iput(lower_inode);
		goto out;
	}
	if (inode->i_state & I_NEW)
		unlock_new_inode(inode);
	else
		iput(lower_inode);
	if (S_ISLNK(lower_inode->i_mode))
		inode->i_op = &ecryptfs_symlink_iops;
	else if (S_ISDIR(lower_inode->i_mode))
		inode->i_op = &ecryptfs_dir_iops;
	if (S_ISDIR(lower_inode->i_mode))
		inode->i_fop = &ecryptfs_dir_fops;
	if (special_file(lower_inode->i_mode))
		init_special_inode(inode, lower_inode->i_mode,
				   lower_inode->i_rdev);
	dentry->d_op = &ecryptfs_dops;
	if (flag)
		d_add(dentry, inode);
	else
		d_instantiate(dentry, inode);
	fsstack_copy_attr_all(inode, lower_inode, NULL);
	/* This size will be overwritten for real files w/ headers and
	 * other metadata */
	fsstack_copy_inode_size(inode, lower_inode);
	rc = ecryptfs_init_persistent_file(dentry);
	if (rc) {
		printk(KERN_ERR "%s: Error attempting to initialize the "
		       "persistent file for the dentry with name [%s]; "
		       "rc = [%d]\n", __FUNCTION__, dentry->d_name.name, rc);
		goto out;
	}
out:
	return rc;
}

enum { ecryptfs_opt_sig, ecryptfs_opt_ecryptfs_sig, ecryptfs_opt_debug,
       ecryptfs_opt_ecryptfs_debug, ecryptfs_opt_cipher,
       ecryptfs_opt_ecryptfs_cipher, ecryptfs_opt_ecryptfs_key_bytes,
       ecryptfs_opt_passthrough, ecryptfs_opt_xattr_metadata,
       ecryptfs_opt_encrypted_view, ecryptfs_opt_err };

static match_table_t tokens = {
	{ecryptfs_opt_sig, "sig=%s"},
	{ecryptfs_opt_ecryptfs_sig, "ecryptfs_sig=%s"},
	{ecryptfs_opt_debug, "debug=%u"},
	{ecryptfs_opt_ecryptfs_debug, "ecryptfs_debug=%u"},
	{ecryptfs_opt_cipher, "cipher=%s"},
	{ecryptfs_opt_ecryptfs_cipher, "ecryptfs_cipher=%s"},
	{ecryptfs_opt_ecryptfs_key_bytes, "ecryptfs_key_bytes=%u"},
	{ecryptfs_opt_passthrough, "ecryptfs_passthrough"},
	{ecryptfs_opt_xattr_metadata, "ecryptfs_xattr_metadata"},
	{ecryptfs_opt_encrypted_view, "ecryptfs_encrypted_view"},
	{ecryptfs_opt_err, NULL}
};

static int ecryptfs_init_global_auth_toks(
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
{
	struct ecryptfs_global_auth_tok *global_auth_tok;
	int rc = 0;

	list_for_each_entry(global_auth_tok,
			    &mount_crypt_stat->global_auth_tok_list,
			    mount_crypt_stat_list) {
		rc = ecryptfs_keyring_auth_tok_for_sig(
			&global_auth_tok->global_auth_tok_key,
			&global_auth_tok->global_auth_tok,
			global_auth_tok->sig);
		if (rc) {
			printk(KERN_ERR "Could not find valid key in user "
			       "session keyring for sig specified in mount "
			       "option: [%s]\n", global_auth_tok->sig);
			global_auth_tok->flags |= ECRYPTFS_AUTH_TOK_INVALID;
			rc = 0;
		} else
			global_auth_tok->flags &= ~ECRYPTFS_AUTH_TOK_INVALID;
	}
	return rc;
}

static void ecryptfs_init_mount_crypt_stat(
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
{
	memset((void *)mount_crypt_stat, 0,
	       sizeof(struct ecryptfs_mount_crypt_stat));
	INIT_LIST_HEAD(&mount_crypt_stat->global_auth_tok_list);
	mutex_init(&mount_crypt_stat->global_auth_tok_list_mutex);
	mount_crypt_stat->flags |= ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED;
}

/**
 * ecryptfs_parse_options
 * @sb: The ecryptfs super block
 * @options: The options pased to the kernel
 *
 * Parse mount options:
 * debug=N 	   - ecryptfs_verbosity level for debug output
 * sig=XXX	   - description(signature) of the key to use
 *
 * Returns the dentry object of the lower-level (lower/interposed)
 * directory; We want to mount our stackable file system on top of
 * that lower directory.
 *
 * The signature of the key to use must be the description of a key
 * already in the keyring. Mounting will fail if the key can not be
 * found.
 *
 * Returns zero on success; non-zero on error
 */
static int ecryptfs_parse_options(struct super_block *sb, char *options)
{
	char *p;
	int rc = 0;
	int sig_set = 0;
	int cipher_name_set = 0;
	int cipher_key_bytes;
	int cipher_key_bytes_set = 0;
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
	substring_t args[MAX_OPT_ARGS];
	int token;
	char *sig_src;
	char *debug_src;
	char *cipher_name_dst;
	char *cipher_name_src;
	char *cipher_key_bytes_src;
	int cipher_name_len;

	if (!options) {
		rc = -EINVAL;
		goto out;
	}
	ecryptfs_init_mount_crypt_stat(mount_crypt_stat);
	while ((p = strsep(&options, ",")) != NULL) {
		if (!*p)
			continue;
		token = match_token(p, tokens, args);
		switch (token) {
		case ecryptfs_opt_sig:
		case ecryptfs_opt_ecryptfs_sig:
			sig_src = args[0].from;
			rc = ecryptfs_add_global_auth_tok(mount_crypt_stat,
							  sig_src);
			if (rc) {
				printk(KERN_ERR "Error attempting to register "
				       "global sig; rc = [%d]\n", rc);
				goto out;
			}
			sig_set = 1;
			break;
		case ecryptfs_opt_debug:
		case ecryptfs_opt_ecryptfs_debug:
			debug_src = args[0].from;
			ecryptfs_verbosity =
				(int)simple_strtol(debug_src, &debug_src,
						   0);
			ecryptfs_printk(KERN_DEBUG,
					"Verbosity set to [%d]" "\n",
					ecryptfs_verbosity);
			break;
		case ecryptfs_opt_cipher:
		case ecryptfs_opt_ecryptfs_cipher:
			cipher_name_src = args[0].from;
			cipher_name_dst =
				mount_crypt_stat->
				global_default_cipher_name;
			strncpy(cipher_name_dst, cipher_name_src,
				ECRYPTFS_MAX_CIPHER_NAME_SIZE);
			ecryptfs_printk(KERN_DEBUG,
					"The mount_crypt_stat "
					"global_default_cipher_name set to: "
					"[%s]\n", cipher_name_dst);
			cipher_name_set = 1;
			break;
		case ecryptfs_opt_ecryptfs_key_bytes:
			cipher_key_bytes_src = args[0].from;
			cipher_key_bytes =
				(int)simple_strtol(cipher_key_bytes_src,
						   &cipher_key_bytes_src, 0);
			mount_crypt_stat->global_default_cipher_key_size =
				cipher_key_bytes;
			ecryptfs_printk(KERN_DEBUG,
					"The mount_crypt_stat "
					"global_default_cipher_key_size "
					"set to: [%d]\n", mount_crypt_stat->
					global_default_cipher_key_size);
			cipher_key_bytes_set = 1;
			break;
		case ecryptfs_opt_passthrough:
			mount_crypt_stat->flags |=
				ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED;
			break;
		case ecryptfs_opt_xattr_metadata:
			mount_crypt_stat->flags |=
				ECRYPTFS_XATTR_METADATA_ENABLED;
			break;
		case ecryptfs_opt_encrypted_view:
			mount_crypt_stat->flags |=
				ECRYPTFS_XATTR_METADATA_ENABLED;
			mount_crypt_stat->flags |=
				ECRYPTFS_ENCRYPTED_VIEW_ENABLED;
			break;
		case ecryptfs_opt_err:
		default:
			ecryptfs_printk(KERN_WARNING,
					"eCryptfs: unrecognized option '%s'\n",
					p);
		}
	}
	if (!sig_set) {
		rc = -EINVAL;
		ecryptfs_printk(KERN_ERR, "You must supply at least one valid "
				"auth tok signature as a mount "
				"parameter; see the eCryptfs README\n");
		goto out;
	}
	if (!cipher_name_set) {
		cipher_name_len = strlen(ECRYPTFS_DEFAULT_CIPHER);
		if (unlikely(cipher_name_len
			     >= ECRYPTFS_MAX_CIPHER_NAME_SIZE)) {
			rc = -EINVAL;
			BUG();
			goto out;
		}
		memcpy(mount_crypt_stat->global_default_cipher_name,
		       ECRYPTFS_DEFAULT_CIPHER, cipher_name_len);
		mount_crypt_stat->global_default_cipher_name[cipher_name_len]
		    = '\0';
	}
	if (!cipher_key_bytes_set) {
		mount_crypt_stat->global_default_cipher_key_size = 0;
	}
	rc = ecryptfs_add_new_key_tfm(
		NULL, mount_crypt_stat->global_default_cipher_name,
		mount_crypt_stat->global_default_cipher_key_size);
	if (rc) {
		printk(KERN_ERR "Error attempting to initialize cipher with "
		       "name = [%s] and key size = [%td]; rc = [%d]\n",
		       mount_crypt_stat->global_default_cipher_name,
		       mount_crypt_stat->global_default_cipher_key_size, rc);
		rc = -EINVAL;
		goto out;
	}
	rc = ecryptfs_init_global_auth_toks(mount_crypt_stat);
	if (rc) {
		printk(KERN_WARNING "One or more global auth toks could not "
		       "properly register; rc = [%d]\n", rc);
	}
	rc = 0;
out:
	return rc;
}

struct kmem_cache *ecryptfs_sb_info_cache;

/**
 * ecryptfs_fill_super
 * @sb: The ecryptfs super block
 * @raw_data: The options passed to mount
 * @silent: Not used but required by function prototype
 *
 * Sets up what we can of the sb, rest is done in ecryptfs_read_super
 *
 * Returns zero on success; non-zero otherwise
 */
static int
ecryptfs_fill_super(struct super_block *sb, void *raw_data, int silent)
{
	int rc = 0;

	/* Released in ecryptfs_put_super() */
	ecryptfs_set_superblock_private(sb,
					kmem_cache_zalloc(ecryptfs_sb_info_cache,
							 GFP_KERNEL));
	if (!ecryptfs_superblock_to_private(sb)) {
		ecryptfs_printk(KERN_WARNING, "Out of memory\n");
		rc = -ENOMEM;
		goto out;
	}
	sb->s_op = &ecryptfs_sops;
	/* Released through deactivate_super(sb) from get_sb_nodev */
	sb->s_root = d_alloc(NULL, &(const struct qstr) {