CRED: Use RCU to access another task's creds and to release a task's own creds

[deliverable/linux.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 046c1609606bc627059aa6cd5df687fa86f15d3b..a512a75a55600896f1dc5782a11c9bdb7f48e948 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -571,8 +571,8 @@ static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
 
        if (inode) {
                inode->i_mode = mode;
-               inode->i_uid = current->fsuid;
-               inode->i_gid = current->fsgid;
+               inode->i_uid = current_fsuid();
+               inode->i_gid = current_fsgid();
                inode->i_blocks = 0;
                inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
                inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
@@ -1279,6 +1279,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
 static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
 {
        struct task_struct *tsk;
+       const struct cred *cred = current_cred(), *tcred;
        int ret;
 
        if (pid) {
@@ -1288,14 +1289,16 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
                        rcu_read_unlock();
                        return -ESRCH;
                }
-               get_task_struct(tsk);
-               rcu_read_unlock();
 
-               if ((current->euid) && (current->euid != tsk->uid)
-                   && (current->euid != tsk->suid)) {
-                       put_task_struct(tsk);
+               tcred = __task_cred(tsk);
+               if (cred->euid &&
+                   cred->euid != tcred->uid &&
+                   cred->euid != tcred->suid) {
+                       rcu_read_unlock();
                        return -EACCES;
                }
+               get_task_struct(tsk);
+               rcu_read_unlock();
        } else {
                tsk = current;
                get_task_struct(tsk);
@@ -2104,7 +2107,7 @@ static void *cgroup_tasks_start(struct seq_file *s, loff_t *pos)
        down_read(&cgrp->pids_mutex);
        if (pid) {
                int end = cgrp->pids_length;
-               int i;
+
                while (index < end) {
                        int mid = (index + end) / 2;
                        if (cgrp->tasks_pids[mid] == pid) {