From 2ecaf55db6dcf4dd25e1ef8d5eb6068e3286a20f Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Mon, 11 Jun 2012 09:47:47 -0700 Subject: 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/miscdev.c | 98 ++++++++++++++------------------------------------- 1 file changed, 26 insertions(+), 72 deletions(-) (limited to 'fs/ecryptfs/miscdev.c') 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", -- cgit v1.2.3