CRED: Wrap task credential accesses in the eCryptFS filesystem

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Mike Halcrow <mhalcrow@us.ibm.com>
Cc: Phillip Hellewell <phillip@hellewell.homeip.net>
Cc: ecryptfs-devel@lists.sourceforge.net
Signed-off-by: James Morris <jmorris@namei.org>

2 files changed, 22 insertions, 16 deletions

diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
index c6983978a31e..e0b0a4e28b9b 100644
--- a/fs/ecryptfs/messaging.c
+++ b/fs/ecryptfs/messaging.c
@@ -361,6 +361,7 @@ int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid,
         size_t msg_size;
         struct nsproxy *nsproxy;
         struct user_namespace *current_user_ns;
+        uid_t ctx_euid;
         int rc;
 
         if (msg->index >= ecryptfs_message_buf_len) {
@@ -385,8 +386,8 @@ int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid,
                 goto wake_up;
         }
         current_user_ns = nsproxy->user_ns;
-        rc = ecryptfs_find_daemon_by_euid(&daemon, msg_ctx->task->euid,
-                                          current_user_ns);
+        ctx_euid = task_euid(msg_ctx->task);
+        rc = ecryptfs_find_daemon_by_euid(&daemon, ctx_euid, current_user_ns);
         rcu_read_unlock();
         mutex_unlock(&ecryptfs_daemon_hash_mux);
         if (rc) {
@@ -394,14 +395,14 @@ int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid,
                 printk(KERN_WARNING "%s: User [%d] received a "
                        "message response from process [0x%p] but does "
                        "not have a registered daemon\n", __func__,
-                       msg_ctx->task->euid, pid);
+                       ctx_euid, pid);
                 goto wake_up;
         }
-        if (msg_ctx->task->euid != euid) {
+        if (ctx_euid != euid) {
                 rc = -EBADMSG;
                 printk(KERN_WARNING "%s: Received message from user "
                        "[%d]; expected message from user [%d]\n", __func__,
-                       euid, msg_ctx->task->euid);
+                       euid, ctx_euid);
                 goto unlock;
         }
         if (current_user_ns != user_ns) {
@@ -415,7 +416,7 @@ int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t euid,
                 rc = -EBADMSG;
                 printk(KERN_ERR "%s: User [%d] sent a message response "
                        "from an unrecognized process [0x%p]\n",
-                       __func__, msg_ctx->task->euid, pid);
+                       __func__, ctx_euid, pid);
                 goto unlock;
         }
         if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
@@ -464,14 +465,15 @@ 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, current->euid,
+        rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
                                           current->nsproxy->user_ns);
         if (rc || !daemon) {
                 rc = -ENOTCONN;
                 printk(KERN_ERR "%s: User [%d] does not have a daemon "
-                       "registered\n", __func__, current->euid);
+                       "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 b484792a0996..047ac609695b 100644
--- a/fs/ecryptfs/miscdev.c
+++ b/fs/ecryptfs/miscdev.c
@@ -42,11 +42,12 @@ ecryptfs_miscdev_poll(struct file *file, poll_table *pt)
 {
         struct ecryptfs_daemon *daemon;
         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, current->euid,
+        rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
                                           current->nsproxy->user_ns);
         BUG_ON(rc || !daemon);
         mutex_lock(&daemon->mux);
@@ -83,6 +84,7 @@ 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);
@@ -93,10 +95,10 @@ 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, current->euid,
+        rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
                                           current->nsproxy->user_ns);
         if (rc || !daemon) {
-                rc = ecryptfs_spawn_daemon(&daemon, current->euid,
+                rc = ecryptfs_spawn_daemon(&daemon, euid,
                                            current->nsproxy->user_ns,
                                            task_pid(current));
                 if (rc) {
@@ -147,10 +149,11 @@ static int
 ecryptfs_miscdev_release(struct inode *inode, struct file *file)
 {
         struct ecryptfs_daemon *daemon = NULL;
+        uid_t euid = current_euid();
         int rc;
 
         mutex_lock(&ecryptfs_daemon_hash_mux);
-        rc = ecryptfs_find_daemon_by_euid(&daemon, current->euid,
+        rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
                                           current->nsproxy->user_ns);
         BUG_ON(rc || !daemon);
         mutex_lock(&daemon->mux);
@@ -246,11 +249,12 @@ ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
         char packet_length[3];
         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, current->euid,
+        rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
                                           current->nsproxy->user_ns);
         BUG_ON(rc || !daemon);
         mutex_lock(&daemon->mux);
@@ -290,7 +294,7 @@ check_list:
                  * message from the queue; try again */
                 goto check_list;
         }
-        BUG_ON(current->euid != daemon->euid);
+        BUG_ON(euid != daemon->euid);
         BUG_ON(current->nsproxy->user_ns != daemon->user_ns);
         BUG_ON(task_pid(current) != daemon->pid);
         msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
@@ -414,6 +418,7 @@ ecryptfs_miscdev_write(struct file *file, const char __user *buf,
         size_t packet_size, packet_size_length, i;
         ssize_t sz = 0;
         char *data;
+        uid_t euid = current_euid();
         int rc;
 
         if (count == 0)
@@ -463,8 +468,7 @@ ecryptfs_miscdev_write(struct file *file, const char __user *buf,
                         goto out_free;
                 }
                 rc = ecryptfs_miscdev_response(&data[i], packet_size,
-                                               current->euid,
-                                               current->nsproxy->user_ns,
+                                               euid, current->nsproxy->user_ns,
                                                task_pid(current), seq);
                 if (rc)
                         printk(KERN_WARNING "%s: Failed to deliver miscdev "