From 2ecaf55db6dcf4dd25e1ef8d5eb6068e3286a20f Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Mon, 11 Jun 2012 09:47:47 -0700 Subject: [PATCH] eCryptfs: Make all miscdev functions use daemon ptr in file private_data Now that a pointer to a valid struct ecryptfs_daemon is stored in the private_data of an opened /dev/ecryptfs file, the remaining miscdev functions can utilize the pointer rather than looking up the ecryptfs_daemon at the beginning of each operation. The security model of /dev/ecryptfs is simplified a little bit with this patch. Upon opening /dev/ecryptfs, a per-user ecryptfs_daemon is registered. Another daemon cannot be registered for that user until the last file reference is released. During the lifetime of the ecryptfs_daemon, access checks are not performed on the /dev/ecryptfs operations because it is assumed that the application securely handles the opened file descriptor and does not unintentionally leak it to processes that are not trusted. Signed-off-by: Tyler Hicks Cc: Sasha Levin --- fs/ecryptfs/ecryptfs_kernel.h | 16 ++---- fs/ecryptfs/messaging.c | 105 ++++++---------------------------- fs/ecryptfs/miscdev.c | 98 +++++++++---------------------- 3 files changed, 47 insertions(+), 172 deletions(-) diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h index 01a1f8575950..0deb4f24957a 100644 --- a/fs/ecryptfs/ecryptfs_kernel.h +++ b/fs/ecryptfs/ecryptfs_kernel.h @@ -392,10 +392,7 @@ struct ecryptfs_daemon { #define ECRYPTFS_DAEMON_MISCDEV_OPEN 0x00000008 u32 flags; u32 num_queued_msg_ctx; - struct pid *pid; - uid_t euid; - struct user_namespace *user_ns; - struct task_struct *task; + struct file *file; struct mutex mux; struct list_head msg_ctx_out_queue; wait_queue_head_t wait; @@ -619,9 +616,8 @@ 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); -int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid, - struct user_namespace *user_ns, struct pid *pid, - u32 seq); +int ecryptfs_process_response(struct ecryptfs_daemon *daemon, + struct ecryptfs_message *msg, u32 seq); int ecryptfs_send_message(char *data, int data_len, struct ecryptfs_msg_ctx **msg_ctx); int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx, @@ -666,8 +662,7 @@ int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs, 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, uid_t euid, - struct user_namespace *user_ns); +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, @@ -679,8 +674,7 @@ int ecryptfs_send_miscdev(char *data, size_t data_size, u16 msg_flags, struct ecryptfs_daemon *daemon); void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx); int -ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, uid_t euid, - struct user_namespace *user_ns, struct pid *pid); +ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, struct file *file); int ecryptfs_init_kthread(void); void ecryptfs_destroy_kthread(void); int ecryptfs_privileged_open(struct file **lower_file, diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c index c11911decdc1..b29bb8bfa8d9 100644 --- a/fs/ecryptfs/messaging.c +++ b/fs/ecryptfs/messaging.c @@ -32,8 +32,8 @@ static struct mutex ecryptfs_msg_ctx_lists_mux; static struct hlist_head *ecryptfs_daemon_hash; struct mutex ecryptfs_daemon_hash_mux; static int ecryptfs_hash_bits; -#define ecryptfs_uid_hash(uid) \ - hash_long((unsigned long)uid, ecryptfs_hash_bits) +#define ecryptfs_current_euid_hash(uid) \ + hash_long((unsigned long)current_euid(), ecryptfs_hash_bits) static u32 ecryptfs_msg_counter; static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr; @@ -105,26 +105,24 @@ void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx) /** * ecryptfs_find_daemon_by_euid - * @euid: The effective user id which maps to the desired daemon id - * @user_ns: The namespace in which @euid applies * @daemon: If return value is zero, points to the desired daemon pointer * * Must be called with ecryptfs_daemon_hash_mux held. * - * Search the hash list for the given user id. + * Search the hash list for the current effective user id. * * Returns zero if the user id exists in the list; non-zero otherwise. */ -int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon, uid_t euid, - struct user_namespace *user_ns) +int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon) { struct hlist_node *elem; int rc; hlist_for_each_entry(*daemon, elem, - &ecryptfs_daemon_hash[ecryptfs_uid_hash(euid)], - euid_chain) { - if ((*daemon)->euid == euid && (*daemon)->user_ns == user_ns) { + &ecryptfs_daemon_hash[ecryptfs_current_euid_hash()], + euid_chain) { + if ((*daemon)->file->f_cred->euid == current_euid() && + (*daemon)->file->f_cred->user_ns == current_user_ns()) { rc = 0; goto out; } @@ -137,9 +135,7 @@ out: /** * ecryptfs_spawn_daemon - Create and initialize a new daemon struct * @daemon: Pointer to set to newly allocated daemon struct - * @euid: Effective user id for the daemon - * @user_ns: The namespace in which @euid applies - * @pid: Process id for the daemon + * @file: File used when opening /dev/ecryptfs * * Must be called ceremoniously while in possession of * ecryptfs_sacred_daemon_hash_mux @@ -147,8 +143,7 @@ out: * Returns zero on success; non-zero otherwise */ int -ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, uid_t euid, - struct user_namespace *user_ns, struct pid *pid) +ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, struct file *file) { int rc = 0; @@ -159,16 +154,13 @@ ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, uid_t euid, "GFP_KERNEL memory\n", __func__, sizeof(**daemon)); goto out; } - (*daemon)->euid = euid; - (*daemon)->user_ns = get_user_ns(user_ns); - (*daemon)->pid = get_pid(pid); - (*daemon)->task = current; + (*daemon)->file = file; mutex_init(&(*daemon)->mux); INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue); init_waitqueue_head(&(*daemon)->wait); (*daemon)->num_queued_msg_ctx = 0; hlist_add_head(&(*daemon)->euid_chain, - &ecryptfs_daemon_hash[ecryptfs_uid_hash(euid)]); + &ecryptfs_daemon_hash[ecryptfs_current_euid_hash()]); out: return rc; } @@ -188,9 +180,6 @@ int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon) if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ) || (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) { rc = -EBUSY; - printk(KERN_WARNING "%s: Attempt to destroy daemon with pid " - "[0x%p], but it is in the midst of a read or a poll\n", - __func__, daemon->pid); mutex_unlock(&daemon->mux); goto out; } @@ -203,12 +192,6 @@ int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon) ecryptfs_msg_ctx_alloc_to_free(msg_ctx); } hlist_del(&daemon->euid_chain); - if (daemon->task) - wake_up_process(daemon->task); - if (daemon->pid) - put_pid(daemon->pid); - if (daemon->user_ns) - put_user_ns(daemon->user_ns); mutex_unlock(&daemon->mux); kzfree(daemon); out: @@ -219,8 +202,6 @@ out: * ecryptfs_process_reponse * @msg: The ecryptfs message received; the caller should sanity check * msg->data_len and free the memory - * @pid: The process ID of the userspace application that sent the - * message * @seq: The sequence number of the message; must match the sequence * number for the existing message context waiting for this * response @@ -239,16 +220,11 @@ out: * * Returns zero on success; non-zero otherwise */ -int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid, - struct user_namespace *user_ns, struct pid *pid, - u32 seq) +int ecryptfs_process_response(struct ecryptfs_daemon *daemon, + struct ecryptfs_message *msg, u32 seq) { - struct ecryptfs_daemon *uninitialized_var(daemon); struct ecryptfs_msg_ctx *msg_ctx; size_t msg_size; - struct nsproxy *nsproxy; - struct user_namespace *tsk_user_ns; - uid_t ctx_euid; int rc; if (msg->index >= ecryptfs_message_buf_len) { @@ -261,51 +237,6 @@ int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid, } msg_ctx = &ecryptfs_msg_ctx_arr[msg->index]; mutex_lock(&msg_ctx->mux); - mutex_lock(&ecryptfs_daemon_hash_mux); - rcu_read_lock(); - nsproxy = task_nsproxy(msg_ctx->task); - if (nsproxy == NULL) { - rc = -EBADMSG; - printk(KERN_ERR "%s: Receiving process is a zombie. Dropping " - "message.\n", __func__); - rcu_read_unlock(); - mutex_unlock(&ecryptfs_daemon_hash_mux); - goto wake_up; - } - tsk_user_ns = __task_cred(msg_ctx->task)->user_ns; - ctx_euid = task_euid(msg_ctx->task); - rc = ecryptfs_find_daemon_by_euid(&daemon, ctx_euid, tsk_user_ns); - rcu_read_unlock(); - mutex_unlock(&ecryptfs_daemon_hash_mux); - if (rc) { - rc = -EBADMSG; - printk(KERN_WARNING "%s: User [%d] received a " - "message response from process [0x%p] but does " - "not have a registered daemon\n", __func__, - ctx_euid, pid); - goto wake_up; - } - if (ctx_euid != euid) { - rc = -EBADMSG; - printk(KERN_WARNING "%s: Received message from user " - "[%d]; expected message from user [%d]\n", __func__, - euid, ctx_euid); - goto unlock; - } - if (tsk_user_ns != user_ns) { - rc = -EBADMSG; - printk(KERN_WARNING "%s: Received message from user_ns " - "[0x%p]; expected message from user_ns [0x%p]\n", - __func__, user_ns, tsk_user_ns); - goto unlock; - } - if (daemon->pid != pid) { - rc = -EBADMSG; - printk(KERN_ERR "%s: User [%d] sent a message response " - "from an unrecognized process [0x%p]\n", - __func__, ctx_euid, pid); - goto unlock; - } if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) { rc = -EINVAL; printk(KERN_WARNING "%s: Desired context element is not " @@ -328,9 +259,8 @@ int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid, } memcpy(msg_ctx->msg, msg, msg_size); msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE; - rc = 0; -wake_up: wake_up_process(msg_ctx->task); + rc = 0; unlock: mutex_unlock(&msg_ctx->mux); out: @@ -352,14 +282,11 @@ ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type, struct ecryptfs_msg_ctx **msg_ctx) { struct ecryptfs_daemon *daemon; - uid_t euid = current_euid(); int rc; - rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); + rc = ecryptfs_find_daemon_by_euid(&daemon); if (rc || !daemon) { rc = -ENOTCONN; - printk(KERN_ERR "%s: User [%d] does not have a daemon " - "registered\n", __func__, euid); goto out; } mutex_lock(&ecryptfs_msg_ctx_lists_mux); diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c index c0038f6566d4..412e6eda25f8 100644 --- a/fs/ecryptfs/miscdev.c +++ b/fs/ecryptfs/miscdev.c @@ -33,7 +33,7 @@ static atomic_t ecryptfs_num_miscdev_opens; /** * ecryptfs_miscdev_poll - * @file: dev file (ignored) + * @file: dev file * @pt: dev poll table (ignored) * * Returns the poll mask @@ -41,20 +41,10 @@ static atomic_t ecryptfs_num_miscdev_opens; static unsigned int ecryptfs_miscdev_poll(struct file *file, poll_table *pt) { - struct ecryptfs_daemon *daemon; + struct ecryptfs_daemon *daemon = file->private_data; unsigned int mask = 0; - uid_t euid = current_euid(); - int rc; - mutex_lock(&ecryptfs_daemon_hash_mux); - /* TODO: Just use file->private_data? */ - rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); - if (rc || !daemon) { - mutex_unlock(&ecryptfs_daemon_hash_mux); - return -EINVAL; - } mutex_lock(&daemon->mux); - mutex_unlock(&ecryptfs_daemon_hash_mux); if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) { printk(KERN_WARNING "%s: Attempt to poll on zombified " "daemon\n", __func__); @@ -79,7 +69,7 @@ out_unlock_daemon: /** * ecryptfs_miscdev_open * @inode: inode of miscdev handle (ignored) - * @file: file for miscdev handle (ignored) + * @file: file for miscdev handle * * Returns zero on success; non-zero otherwise */ @@ -87,7 +77,6 @@ static int ecryptfs_miscdev_open(struct inode *inode, struct file *file) { struct ecryptfs_daemon *daemon = NULL; - uid_t euid = current_euid(); int rc; mutex_lock(&ecryptfs_daemon_hash_mux); @@ -98,30 +87,20 @@ ecryptfs_miscdev_open(struct inode *inode, struct file *file) "count; rc = [%d]\n", __func__, rc); goto out_unlock_daemon_list; } - rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); - if (rc || !daemon) { - rc = ecryptfs_spawn_daemon(&daemon, euid, current_user_ns(), - task_pid(current)); - if (rc) { - printk(KERN_ERR "%s: Error attempting to spawn daemon; " - "rc = [%d]\n", __func__, rc); - goto out_module_put_unlock_daemon_list; - } - } - mutex_lock(&daemon->mux); - if (daemon->pid != task_pid(current)) { + rc = ecryptfs_find_daemon_by_euid(&daemon); + if (!rc) { rc = -EINVAL; - printk(KERN_ERR "%s: pid [0x%p] has registered with euid [%d], " - "but pid [0x%p] has attempted to open the handle " - "instead\n", __func__, daemon->pid, daemon->euid, - task_pid(current)); - goto out_unlock_daemon; + goto out_unlock_daemon_list; + } + rc = ecryptfs_spawn_daemon(&daemon, file); + if (rc) { + printk(KERN_ERR "%s: Error attempting to spawn daemon; " + "rc = [%d]\n", __func__, rc); + goto out_module_put_unlock_daemon_list; } + mutex_lock(&daemon->mux); if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) { rc = -EBUSY; - printk(KERN_ERR "%s: Miscellaneous device handle may only be " - "opened once per daemon; pid [0x%p] already has this " - "handle open\n", __func__, daemon->pid); goto out_unlock_daemon; } daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN; @@ -140,7 +119,7 @@ out_unlock_daemon_list: /** * ecryptfs_miscdev_release * @inode: inode of fs/ecryptfs/euid handle (ignored) - * @file: file for fs/ecryptfs/euid handle (ignored) + * @file: file for fs/ecryptfs/euid handle * * This keeps the daemon registered until the daemon sends another * ioctl to fs/ecryptfs/ctl or until the kernel module unregisters. @@ -150,20 +129,18 @@ out_unlock_daemon_list: static int ecryptfs_miscdev_release(struct inode *inode, struct file *file) { - struct ecryptfs_daemon *daemon = NULL; - uid_t euid = current_euid(); + struct ecryptfs_daemon *daemon = file->private_data; int rc; - mutex_lock(&ecryptfs_daemon_hash_mux); - rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); - if (rc || !daemon) - daemon = file->private_data; mutex_lock(&daemon->mux); BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN)); daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN; atomic_dec(&ecryptfs_num_miscdev_opens); mutex_unlock(&daemon->mux); + + mutex_lock(&ecryptfs_daemon_hash_mux); rc = ecryptfs_exorcise_daemon(daemon); + mutex_unlock(&ecryptfs_daemon_hash_mux); if (rc) { printk(KERN_CRIT "%s: Fatal error whilst attempting to " "shut down daemon; rc = [%d]. Please report this " @@ -171,7 +148,6 @@ ecryptfs_miscdev_release(struct inode *inode, struct file *file) BUG(); } module_put(THIS_MODULE); - mutex_unlock(&ecryptfs_daemon_hash_mux); return rc; } @@ -248,7 +224,7 @@ int ecryptfs_send_miscdev(char *data, size_t data_size, /** * ecryptfs_miscdev_read - format and send message from queue - * @file: fs/ecryptfs/euid miscdevfs handle (ignored) + * @file: miscdevfs handle * @buf: User buffer into which to copy the next message on the daemon queue * @count: Amount of space available in @buf * @ppos: Offset in file (ignored) @@ -262,43 +238,27 @@ static ssize_t ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { - struct ecryptfs_daemon *daemon; + struct ecryptfs_daemon *daemon = file->private_data; struct ecryptfs_msg_ctx *msg_ctx; size_t packet_length_size; char packet_length[ECRYPTFS_MAX_PKT_LEN_SIZE]; size_t i; size_t total_length; - uid_t euid = current_euid(); int rc; - mutex_lock(&ecryptfs_daemon_hash_mux); - /* TODO: Just use file->private_data? */ - rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); - if (rc || !daemon) { - mutex_unlock(&ecryptfs_daemon_hash_mux); - return -EINVAL; - } mutex_lock(&daemon->mux); - if (task_pid(current) != daemon->pid) { - mutex_unlock(&daemon->mux); - mutex_unlock(&ecryptfs_daemon_hash_mux); - return -EPERM; - } if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) { rc = 0; - mutex_unlock(&ecryptfs_daemon_hash_mux); printk(KERN_WARNING "%s: Attempt to read from zombified " "daemon\n", __func__); goto out_unlock_daemon; } if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) { rc = 0; - mutex_unlock(&ecryptfs_daemon_hash_mux); goto out_unlock_daemon; } /* This daemon will not go away so long as this flag is set */ daemon->flags |= ECRYPTFS_DAEMON_IN_READ; - mutex_unlock(&ecryptfs_daemon_hash_mux); check_list: if (list_empty(&daemon->msg_ctx_out_queue)) { mutex_unlock(&daemon->mux); @@ -382,16 +342,12 @@ out_unlock_daemon: * ecryptfs_miscdev_response - miscdevess response to message previously sent to daemon * @data: Bytes comprising struct ecryptfs_message * @data_size: sizeof(struct ecryptfs_message) + data len - * @euid: Effective user id of miscdevess sending the miscdev response - * @user_ns: The namespace in which @euid applies - * @pid: Miscdevess id of miscdevess sending the miscdev response * @seq: Sequence number for miscdev response packet * * Returns zero on success; non-zero otherwise */ -static int ecryptfs_miscdev_response(char *data, size_t data_size, - uid_t euid, struct user_namespace *user_ns, - struct pid *pid, u32 seq) +static int ecryptfs_miscdev_response(struct ecryptfs_daemon *daemon, char *data, + size_t data_size, u32 seq) { struct ecryptfs_message *msg = (struct ecryptfs_message *)data; int rc; @@ -403,7 +359,7 @@ static int ecryptfs_miscdev_response(char *data, size_t data_size, rc = -EINVAL; goto out; } - rc = ecryptfs_process_response(msg, euid, user_ns, pid, seq); + rc = ecryptfs_process_response(daemon, msg, seq); if (rc) printk(KERN_ERR "Error processing response message; rc = [%d]\n", rc); @@ -413,7 +369,7 @@ out: /** * ecryptfs_miscdev_write - handle write to daemon miscdev handle - * @file: File for misc dev handle (ignored) + * @file: File for misc dev handle * @buf: Buffer containing user data * @count: Amount of data in @buf * @ppos: Pointer to offset in file (ignored) @@ -428,7 +384,6 @@ ecryptfs_miscdev_write(struct file *file, const char __user *buf, u32 seq; size_t packet_size, packet_size_length; char *data; - uid_t euid = current_euid(); unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE]; ssize_t rc; @@ -488,10 +443,9 @@ memdup: } memcpy(&counter_nbo, &data[PKT_CTR_OFFSET], PKT_CTR_SIZE); seq = be32_to_cpu(counter_nbo); - rc = ecryptfs_miscdev_response( + rc = ecryptfs_miscdev_response(file->private_data, &data[PKT_LEN_OFFSET + packet_size_length], - packet_size, euid, current_user_ns(), - task_pid(current), seq); + packet_size, seq); if (rc) { printk(KERN_WARNING "%s: Failed to deliver miscdev " "response to requesting operation; rc = [%zd]\n", -- 2.30.2