lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

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

Browse Source 
Use RCU to access another task's creds and to release a task's own creds.
This means that it will be possible for the credentials of a task to be
replaced without another task (a) requiring a full lock to read them, and (b)
seeing deallocated memory.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
David Howells
2008-11-14 10:39:19 +11:00
committed by James Morris
parent 86a264abe5
commit c69e8d9c01
28 changed files with 353 additions and 202 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
fs/ioprio.c
View File

@@ -31,10 +31,16 @@ static int set_task_ioprio(struct task_struct *task, int ioprio)
{
int err;
struct io_context *ioc;
const struct cred *cred = current_cred(), *tcred;
if (task->cred->uid != current_euid() &&
task->cred->uid != current_uid() && !capable(CAP_SYS_NICE))
rcu_read_lock();
tcred = __task_cred(task);
if (tcred->uid != cred->euid &&
tcred->uid != cred->uid && !capable(CAP_SYS_NICE)) {
rcu_read_unlock();
return -EPERM;
}
rcu_read_unlock();
err = security_task_setioprio(task, ioprio);
if (err)
@@ -131,7 +137,7 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
break;
do_each_thread(g, p) {
if (p->cred->uid != who)
if (__task_cred(p)->uid != who)
continue;
ret = set_task_ioprio(p, ioprio);
if (ret)
@@ -224,7 +230,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
break;
do_each_thread(g, p) {
if (p->cred->uid != user->uid)
if (__task_cred(p)->uid != user->uid)
continue;
tmpio = get_task_ioprio(p);
if (tmpio < 0)