From 290502bee239062499297916bb7d21d205e99d62 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 28 Feb 2013 00:39:37 -0800 Subject: 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: Kees Cook Signed-off-by: Tyler Hicks --- fs/ecryptfs/Kconfig | 8 ++++++++ fs/ecryptfs/Makefile | 7 +++++-- fs/ecryptfs/ecryptfs_kernel.h | 40 ++++++++++++++++++++++++++++++++++++++-- fs/ecryptfs/keystore.c | 4 ++-- include/linux/ecryptfs.h | 12 ++---------- 5 files changed, 55 insertions(+), 16 deletions(-) diff --git a/fs/ecryptfs/Kconfig b/fs/ecryptfs/Kconfig index cc16562654de..1f63120b669a 100644 --- a/fs/ecryptfs/Kconfig +++ b/fs/ecryptfs/Kconfig @@ -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. diff --git a/fs/ecryptfs/Makefile b/fs/ecryptfs/Makefile index 2cc9ee4ad2eb..49678a69947d 100644 --- a/fs/ecryptfs/Makefile +++ b/fs/ecryptfs/Makefile @@ -1,7 +1,10 @@ # -# 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 diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h index cfb4b9fed520..a9df69efadc2 100644 --- a/fs/ecryptfs/ecryptfs_kernel.h +++ b/fs/ecryptfs/ecryptfs_kernel.h @@ -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, diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c index 5aceff202dc0..7d52806c2119 100644 --- a/fs/ecryptfs/keystore.c +++ b/fs/ecryptfs/keystore.c @@ -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); diff --git a/include/linux/ecryptfs.h b/include/linux/ecryptfs.h index 2224a8c0cb64..8d5ab998a222 100644 --- a/include/linux/ecryptfs.h +++ b/include/linux/ecryptfs.h @@ -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 -- cgit v1.2.3