Commit 290502be authored by Kees Cook's avatar Kees Cook Committed by Tyler Hicks
Browse files

eCryptfs: allow userspace messaging to be disabled 



When the userspace messaging (for the less common case of userspace key
wrap/unwrap via ecryptfsd) is not needed, allow eCryptfs to build with
it removed. This saves on kernel code size and reduces potential attack
surface by removing the /dev/ecryptfs node.

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarTyler Hicks <tyhicks@canonical.com>
parent 1111eae9

fs/ecryptfs/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -12,3 +12,11 @@ config ECRYPT_FS 


	  To compile this file system support as a module, choose M here: the

	  module will be called ecryptfs.



config ECRYPT_FS_MESSAGING

	bool "Enable notifications for userspace key wrap/unwrap"

	depends on ECRYPT_FS

	help

	  Enables the /dev/ecryptfs entry for use by ecryptfsd. This allows

	  for userspace to wrap/unwrap file encryption keys by other

	  backends, like OpenSSL.

fs/ecryptfs/Makefile

+5 −2
Original line number Diff line number Diff line 
#

# Makefile for the Linux 2.6 eCryptfs

# Makefile for the Linux eCryptfs

#



obj-$(CONFIG_ECRYPT_FS) += ecryptfs.o



ecryptfs-objs := dentry.o file.o inode.o main.o super.o mmap.o read_write.o crypto.o keystore.o messaging.o miscdev.o kthread.o debug.o
 
ecryptfs-y := dentry.o file.o inode.o main.o super.o mmap.o read_write.o \

	      crypto.o keystore.o kthread.o debug.o



ecryptfs-$(CONFIG_ECRYPT_FS_MESSAGING) += messaging.o miscdev.o

fs/ecryptfs/ecryptfs_kernel.h

+38 −2
Original line number Diff line number Diff line
@@ -172,6 +172,19 @@ ecryptfs_get_key_payload_data(struct key *key) 
#define ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE 24

#define ECRYPTFS_ENCRYPTED_DENTRY_NAME_LEN (18 + 1 + 4 + 1 + 32)



#ifdef CONFIG_ECRYPT_FS_MESSAGING

# define ECRYPTFS_VERSIONING_MASK_MESSAGING (ECRYPTFS_VERSIONING_DEVMISC \

					     | ECRYPTFS_VERSIONING_PUBKEY)

#else

# define ECRYPTFS_VERSIONING_MASK_MESSAGING 0

#endif



#define ECRYPTFS_VERSIONING_MASK (ECRYPTFS_VERSIONING_PASSPHRASE \

				  | ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH \

				  | ECRYPTFS_VERSIONING_XATTR \

				  | ECRYPTFS_VERSIONING_MULTKEY \

				  | ECRYPTFS_VERSIONING_MASK_MESSAGING \

				  | ECRYPTFS_VERSIONING_FILENAME_ENCRYPTION)

struct ecryptfs_key_sig {

	struct list_head crypt_stat_list;

	char keysig[ECRYPTFS_SIG_SIZE_HEX + 1];
@@ -399,7 +412,9 @@ struct ecryptfs_daemon { 
	struct hlist_node euid_chain;

};



#ifdef CONFIG_ECRYPT_FS_MESSAGING

extern struct mutex ecryptfs_daemon_hash_mux;

#endif



static inline size_t

ecryptfs_lower_header_size(struct ecryptfs_crypt_stat *crypt_stat)
@@ -604,6 +619,7 @@ int 
ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,

		  size_t size, int flags);

int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode);

#ifdef CONFIG_ECRYPT_FS_MESSAGING

int ecryptfs_process_response(struct ecryptfs_daemon *daemon,

			      struct ecryptfs_message *msg, u32 seq);

int ecryptfs_send_message(char *data, int data_len,
@@ -612,6 +628,24 @@ int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx, 
			       struct ecryptfs_message **emsg);

int ecryptfs_init_messaging(void);

void ecryptfs_release_messaging(void);

#else

static inline int ecryptfs_init_messaging(void)

{

	return 0;

}

static inline void ecryptfs_release_messaging(void)

{ }

static inline int ecryptfs_send_message(char *data, int data_len,

					struct ecryptfs_msg_ctx **msg_ctx)

{

	return -ENOTCONN;

}

static inline int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,

					     struct ecryptfs_message **emsg)

{

	return -ENOMSG;

}

#endif



void

ecryptfs_write_header_metadata(char *virt,
@@ -649,12 +683,11 @@ int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs, 
				     size_t offset_in_page, size_t size,

				     struct inode *ecryptfs_inode);

struct page *ecryptfs_get_locked_page(struct inode *inode, loff_t index);

int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon);

int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon);

int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,

				 size_t *length_size);

int ecryptfs_write_packet_length(char *dest, size_t size,

				 size_t *packet_size_length);

#ifdef CONFIG_ECRYPT_FS_MESSAGING

int ecryptfs_init_ecryptfs_miscdev(void);

void ecryptfs_destroy_ecryptfs_miscdev(void);

int ecryptfs_send_miscdev(char *data, size_t data_size,
@@ -663,6 +696,9 @@ int ecryptfs_send_miscdev(char *data, size_t data_size, 
void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx);

int

ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, struct file *file);

int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon);

int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon);

#endif

int ecryptfs_init_kthread(void);

void ecryptfs_destroy_kthread(void);

int ecryptfs_privileged_open(struct file **lower_file,

fs/ecryptfs/keystore.c

+2 −2
Original line number Diff line number Diff line
@@ -1168,7 +1168,7 @@ decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok, 
	rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);

	if (rc) {

		ecryptfs_printk(KERN_ERR, "Error sending message to "

				"ecryptfsd\n");

				"ecryptfsd: %d\n", rc);

		goto out;

	}

	rc = ecryptfs_wait_for_response(msg_ctx, &msg);
@@ -1988,7 +1988,7 @@ pki_encrypt_session_key(struct key *auth_tok_key, 
	rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);

	if (rc) {

		ecryptfs_printk(KERN_ERR, "Error sending message to "

				"ecryptfsd\n");

				"ecryptfsd: %d\n", rc);

		goto out;

	}

	rc = ecryptfs_wait_for_response(msg_ctx, &msg);

include/linux/ecryptfs.h

+2 −10
Original line number Diff line number Diff line
@@ -6,9 +6,8 @@ 
#define ECRYPTFS_VERSION_MINOR 0x04

#define ECRYPTFS_SUPPORTED_FILE_VERSION 0x03

/* These flags indicate which features are supported by the kernel

 * module; userspace tools such as the mount helper read

 * ECRYPTFS_VERSIONING_MASK from a sysfs handle in order to determine

 * how to behave. */

 * module; userspace tools such as the mount helper read the feature

 * bits from a sysfs handle in order to determine how to behave. */

#define ECRYPTFS_VERSIONING_PASSPHRASE            0x00000001

#define ECRYPTFS_VERSIONING_PUBKEY                0x00000002

#define ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH 0x00000004
@@ -19,13 +18,6 @@ 
#define ECRYPTFS_VERSIONING_HMAC                  0x00000080

#define ECRYPTFS_VERSIONING_FILENAME_ENCRYPTION   0x00000100

#define ECRYPTFS_VERSIONING_GCM                   0x00000200

#define ECRYPTFS_VERSIONING_MASK (ECRYPTFS_VERSIONING_PASSPHRASE \

				  | ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH \

				  | ECRYPTFS_VERSIONING_PUBKEY \

				  | ECRYPTFS_VERSIONING_XATTR \

				  | ECRYPTFS_VERSIONING_MULTKEY \

				  | ECRYPTFS_VERSIONING_DEVMISC \

				  | ECRYPTFS_VERSIONING_FILENAME_ENCRYPTION)

#define ECRYPTFS_MAX_PASSWORD_LENGTH 64

#define ECRYPTFS_MAX_PASSPHRASE_BYTES ECRYPTFS_MAX_PASSWORD_LENGTH

#define ECRYPTFS_SALT_SIZE 8

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