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
......@@ -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.
#
# 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
......@@ -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,
......
......@@ -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);
......
......@@ -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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