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 <tyhicks@canonical.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
index c11911d..b29bb8b 100644
--- a/fs/ecryptfs/messaging.c
+++ b/fs/ecryptfs/messaging.c
@@ -32,8 +32,8 @@
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 @@
/**
* 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 @@
/**
* 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 @@
* 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 @@
"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 @@
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 @@
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 @@
* 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 @@
*
* 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 @@
}
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 @@
}
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 @@
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);