main.c

linux 内核源代码

			     .hash = 0,.name = "/",.len = 1});
	if (!sb->s_root) {
		ecryptfs_printk(KERN_ERR, "d_alloc failed\n");
		rc = -ENOMEM;
		goto out;
	}
	sb->s_root->d_op = &ecryptfs_dops;
	sb->s_root->d_sb = sb;
	sb->s_root->d_parent = sb->s_root;
	/* Released in d_release when dput(sb->s_root) is called */
	/* through deactivate_super(sb) from get_sb_nodev() */
	ecryptfs_set_dentry_private(sb->s_root,
				    kmem_cache_zalloc(ecryptfs_dentry_info_cache,
						     GFP_KERNEL));
	if (!ecryptfs_dentry_to_private(sb->s_root)) {
		ecryptfs_printk(KERN_ERR,
				"dentry_info_cache alloc failed\n");
		rc = -ENOMEM;
		goto out;
	}
	rc = 0;
out:
	/* Should be able to rely on deactivate_super called from
	 * get_sb_nodev */
	return rc;
}

/**
 * ecryptfs_read_super
 * @sb: The ecryptfs super block
 * @dev_name: The path to mount over
 *
 * Read the super block of the lower filesystem, and use
 * ecryptfs_interpose to create our initial inode and super block
 * struct.
 */
static int ecryptfs_read_super(struct super_block *sb, const char *dev_name)
{
	int rc;
	struct nameidata nd;
	struct dentry *lower_root;
	struct vfsmount *lower_mnt;

	memset(&nd, 0, sizeof(struct nameidata));
	rc = path_lookup(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &nd);
	if (rc) {
		ecryptfs_printk(KERN_WARNING, "path_lookup() failed\n");
		goto out;
	}
	lower_root = nd.dentry;
	lower_mnt = nd.mnt;
	ecryptfs_set_superblock_lower(sb, lower_root->d_sb);
	sb->s_maxbytes = lower_root->d_sb->s_maxbytes;
	sb->s_blocksize = lower_root->d_sb->s_blocksize;
	ecryptfs_set_dentry_lower(sb->s_root, lower_root);
	ecryptfs_set_dentry_lower_mnt(sb->s_root, lower_mnt);
	rc = ecryptfs_interpose(lower_root, sb->s_root, sb, 0);
	if (rc)
		goto out_free;
	rc = 0;
	goto out;
out_free:
	path_release(&nd);
out:
	return rc;
}

/**
 * ecryptfs_get_sb
 * @fs_type
 * @flags
 * @dev_name: The path to mount over
 * @raw_data: The options passed into the kernel
 *
 * The whole ecryptfs_get_sb process is broken into 4 functions:
 * ecryptfs_parse_options(): handle options passed to ecryptfs, if any
 * ecryptfs_fill_super(): used by get_sb_nodev, fills out the super_block
 *                        with as much information as it can before needing
 *                        the lower filesystem.
 * ecryptfs_read_super(): this accesses the lower filesystem and uses
 *                        ecryptfs_interpolate to perform most of the linking
 * ecryptfs_interpolate(): links the lower filesystem into ecryptfs
 */
static int ecryptfs_get_sb(struct file_system_type *fs_type, int flags,
			const char *dev_name, void *raw_data,
			struct vfsmount *mnt)
{
	int rc;
	struct super_block *sb;

	rc = get_sb_nodev(fs_type, flags, raw_data, ecryptfs_fill_super, mnt);
	if (rc < 0) {
		printk(KERN_ERR "Getting sb failed; rc = [%d]\n", rc);
		goto out;
	}
	sb = mnt->mnt_sb;
	rc = ecryptfs_parse_options(sb, raw_data);
	if (rc) {
		printk(KERN_ERR "Error parsing options; rc = [%d]\n", rc);
		goto out_abort;
	}
	rc = ecryptfs_read_super(sb, dev_name);
	if (rc) {
		printk(KERN_ERR "Reading sb failed; rc = [%d]\n", rc);
		goto out_abort;
	}
	goto out;
out_abort:
	dput(sb->s_root);
	up_write(&sb->s_umount);
	deactivate_super(sb);
out:
	return rc;
}

/**
 * ecryptfs_kill_block_super
 * @sb: The ecryptfs super block
 *
 * Used to bring the superblock down and free the private data.
 * Private data is free'd in ecryptfs_put_super()
 */
static void ecryptfs_kill_block_super(struct super_block *sb)
{
	generic_shutdown_super(sb);
}

static struct file_system_type ecryptfs_fs_type = {
	.owner = THIS_MODULE,
	.name = "ecryptfs",
	.get_sb = ecryptfs_get_sb,
	.kill_sb = ecryptfs_kill_block_super,
	.fs_flags = 0
};

/**
 * inode_info_init_once
 *
 * Initializes the ecryptfs_inode_info_cache when it is created
 */
static void
inode_info_init_once(struct kmem_cache *cachep, void *vptr)
{
	struct ecryptfs_inode_info *ei = (struct ecryptfs_inode_info *)vptr;

	inode_init_once(&ei->vfs_inode);
}

static struct ecryptfs_cache_info {
	struct kmem_cache **cache;
	const char *name;
	size_t size;
	void (*ctor)(struct kmem_cache *cache, void *obj);
} ecryptfs_cache_infos[] = {
	{
		.cache = &ecryptfs_auth_tok_list_item_cache,
		.name = "ecryptfs_auth_tok_list_item",
		.size = sizeof(struct ecryptfs_auth_tok_list_item),
	},
	{
		.cache = &ecryptfs_file_info_cache,
		.name = "ecryptfs_file_cache",
		.size = sizeof(struct ecryptfs_file_info),
	},
	{
		.cache = &ecryptfs_dentry_info_cache,
		.name = "ecryptfs_dentry_info_cache",
		.size = sizeof(struct ecryptfs_dentry_info),
	},
	{
		.cache = &ecryptfs_inode_info_cache,
		.name = "ecryptfs_inode_cache",
		.size = sizeof(struct ecryptfs_inode_info),
		.ctor = inode_info_init_once,
	},
	{
		.cache = &ecryptfs_sb_info_cache,
		.name = "ecryptfs_sb_cache",
		.size = sizeof(struct ecryptfs_sb_info),
	},
	{
		.cache = &ecryptfs_header_cache_0,
		.name = "ecryptfs_headers_0",
		.size = PAGE_CACHE_SIZE,
	},
	{
		.cache = &ecryptfs_header_cache_1,
		.name = "ecryptfs_headers_1",
		.size = PAGE_CACHE_SIZE,
	},
	{
		.cache = &ecryptfs_header_cache_2,
		.name = "ecryptfs_headers_2",
		.size = PAGE_CACHE_SIZE,
	},
	{
		.cache = &ecryptfs_xattr_cache,
		.name = "ecryptfs_xattr_cache",
		.size = PAGE_CACHE_SIZE,
	},
	{
		.cache = &ecryptfs_key_record_cache,
		.name = "ecryptfs_key_record_cache",
		.size = sizeof(struct ecryptfs_key_record),
	},
	{
		.cache = &ecryptfs_key_sig_cache,
		.name = "ecryptfs_key_sig_cache",
		.size = sizeof(struct ecryptfs_key_sig),
	},
	{
		.cache = &ecryptfs_global_auth_tok_cache,
		.name = "ecryptfs_global_auth_tok_cache",
		.size = sizeof(struct ecryptfs_global_auth_tok),
	},
	{
		.cache = &ecryptfs_key_tfm_cache,
		.name = "ecryptfs_key_tfm_cache",
		.size = sizeof(struct ecryptfs_key_tfm),
	},
};

static void ecryptfs_free_kmem_caches(void)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
		struct ecryptfs_cache_info *info;

		info = &ecryptfs_cache_infos[i];
		if (*(info->cache))
			kmem_cache_destroy(*(info->cache));
	}
}

/**
 * ecryptfs_init_kmem_caches
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_init_kmem_caches(void)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
		struct ecryptfs_cache_info *info;

		info = &ecryptfs_cache_infos[i];
		*(info->cache) = kmem_cache_create(info->name, info->size,
				0, SLAB_HWCACHE_ALIGN, info->ctor);
		if (!*(info->cache)) {
			ecryptfs_free_kmem_caches();
			ecryptfs_printk(KERN_WARNING, "%s: "
					"kmem_cache_create failed\n",
					info->name);
			return -ENOMEM;
		}
	}
	return 0;
}

struct ecryptfs_obj {
	char *name;
	struct list_head slot_list;
	struct kobject kobj;
};

struct ecryptfs_attribute {
	struct attribute attr;
	ssize_t(*show) (struct ecryptfs_obj *, char *);
	ssize_t(*store) (struct ecryptfs_obj *, const char *, size_t);
};

static ssize_t
ecryptfs_attr_store(struct kobject *kobj,
		    struct attribute *attr, const char *buf, size_t len)
{
	struct ecryptfs_obj *obj = container_of(kobj, struct ecryptfs_obj,
						kobj);
	struct ecryptfs_attribute *attribute =
		container_of(attr, struct ecryptfs_attribute, attr);

	return (attribute->store ? attribute->store(obj, buf, len) : 0);
}

static ssize_t
ecryptfs_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
{
	struct ecryptfs_obj *obj = container_of(kobj, struct ecryptfs_obj,
						kobj);
	struct ecryptfs_attribute *attribute =
		container_of(attr, struct ecryptfs_attribute, attr);

	return (attribute->show ? attribute->show(obj, buf) : 0);
}

static struct sysfs_ops ecryptfs_sysfs_ops = {
	.show = ecryptfs_attr_show,
	.store = ecryptfs_attr_store
};

static struct kobj_type ecryptfs_ktype = {
	.sysfs_ops = &ecryptfs_sysfs_ops
};

static decl_subsys(ecryptfs, &ecryptfs_ktype, NULL);

static ssize_t version_show(struct ecryptfs_obj *obj, char *buff)
{
	return snprintf(buff, PAGE_SIZE, "%d\n", ECRYPTFS_VERSIONING_MASK);
}

static struct ecryptfs_attribute sysfs_attr_version = __ATTR_RO(version);

static struct ecryptfs_version_str_map_elem {
	u32 flag;
	char *str;
} ecryptfs_version_str_map[] = {
	{ECRYPTFS_VERSIONING_PASSPHRASE, "passphrase"},
	{ECRYPTFS_VERSIONING_PUBKEY, "pubkey"},
	{ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH, "plaintext passthrough"},
	{ECRYPTFS_VERSIONING_POLICY, "policy"},
	{ECRYPTFS_VERSIONING_XATTR, "metadata in extended attribute"},
	{ECRYPTFS_VERSIONING_MULTKEY, "multiple keys per file"}
};

static ssize_t version_str_show(struct ecryptfs_obj *obj, char *buff)
{
	int i;
	int remaining = PAGE_SIZE;
	int total_written = 0;

	buff[0] = '\0';
	for (i = 0; i < ARRAY_SIZE(ecryptfs_version_str_map); i++) {
		int entry_size;

		if (!(ECRYPTFS_VERSIONING_MASK
		      & ecryptfs_version_str_map[i].flag))
			continue;
		entry_size = strlen(ecryptfs_version_str_map[i].str);
		if ((entry_size + 2) > remaining)
			goto out;
		memcpy(buff, ecryptfs_version_str_map[i].str, entry_size);
		buff[entry_size++] = '\n';
		buff[entry_size] = '\0';
		buff += entry_size;
		total_written += entry_size;
		remaining -= entry_size;
	}
out:
	return total_written;
}

static struct ecryptfs_attribute sysfs_attr_version_str = __ATTR_RO(version_str);

static int do_sysfs_registration(void)
{
	int rc;

	rc = subsystem_register(&ecryptfs_subsys);
	if (rc) {
		printk(KERN_ERR
		       "Unable to register ecryptfs sysfs subsystem\n");
		goto out;
	}
	rc = sysfs_create_file(&ecryptfs_subsys.kobj,
			       &sysfs_attr_version.attr);
	if (rc) {
		printk(KERN_ERR
		       "Unable to create ecryptfs version attribute\n");
		subsystem_unregister(&ecryptfs_subsys);
		goto out;
	}
	rc = sysfs_create_file(&ecryptfs_subsys.kobj,
			       &sysfs_attr_version_str.attr);
	if (rc) {
		printk(KERN_ERR
		       "Unable to create ecryptfs version_str attribute\n");
		sysfs_remove_file(&ecryptfs_subsys.kobj,
				  &sysfs_attr_version.attr);
		subsystem_unregister(&ecryptfs_subsys);
		goto out;
	}
out:
	return rc;
}

static void do_sysfs_unregistration(void)
{
	sysfs_remove_file(&ecryptfs_subsys.kobj,
			  &sysfs_attr_version.attr);
	sysfs_remove_file(&ecryptfs_subsys.kobj,
			  &sysfs_attr_version_str.attr);
	subsystem_unregister(&ecryptfs_subsys);
}

static int __init ecryptfs_init(void)
{
	int rc;

	if (ECRYPTFS_DEFAULT_EXTENT_SIZE > PAGE_CACHE_SIZE) {
		rc = -EINVAL;
		ecryptfs_printk(KERN_ERR, "The eCryptfs extent size is "
				"larger than the host's page size, and so "
				"eCryptfs cannot run on this system. The "
				"default eCryptfs extent size is [%d] bytes; "
				"the page size is [%d] bytes.\n",
				ECRYPTFS_DEFAULT_EXTENT_SIZE, PAGE_CACHE_SIZE);
		goto out;
	}
	rc = ecryptfs_init_kmem_caches();
	if (rc) {
		printk(KERN_ERR
		       "Failed to allocate one or more kmem_cache objects\n");
		goto out;
	}
	rc = register_filesystem(&ecryptfs_fs_type);
	if (rc) {
		printk(KERN_ERR "Failed to register filesystem\n");
		goto out_free_kmem_caches;
	}
	kobj_set_kset_s(&ecryptfs_subsys, fs_subsys);
	rc = do_sysfs_registration();
	if (rc) {
		printk(KERN_ERR "sysfs registration failed\n");
		goto out_unregister_filesystem;
	}
	rc = ecryptfs_init_messaging(ecryptfs_transport);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Failure occured while attempting to "
				"initialize the eCryptfs netlink socket\n");
		goto out_do_sysfs_unregistration;
	}
	rc = ecryptfs_init_crypto();
	if (rc) {
		printk(KERN_ERR "Failure whilst attempting to init crypto; "
		       "rc = [%d]\n", rc);
		goto out_release_messaging;
	}
	goto out;
out_release_messaging:
	ecryptfs_release_messaging(ecryptfs_transport);
out_do_sysfs_unregistration:
	do_sysfs_unregistration();
out_unregister_filesystem:
	unregister_filesystem(&ecryptfs_fs_type);
out_free_kmem_caches:
	ecryptfs_free_kmem_caches();
out:
	return rc;
}

static void __exit ecryptfs_exit(void)
{
	int rc;

	rc = ecryptfs_destroy_crypto();
	if (rc)
		printk(KERN_ERR "Failure whilst attempting to destroy crypto; "
		       "rc = [%d]\n", rc);
	ecryptfs_release_messaging(ecryptfs_transport);
	do_sysfs_unregistration();
	unregister_filesystem(&ecryptfs_fs_type);
	ecryptfs_free_kmem_caches();
}

MODULE_AUTHOR("Michael A. Halcrow <[e-mail]>");
MODULE_DESCRIPTION("eCryptfs");

MODULE_LICENSE("GPL");

module_init(ecryptfs_init)
module_exit(ecryptfs_exit)