For the people who missed the beginning of the discussion, the
following patch is an extension of the existing getrusage syscall()
and it applies to the 2.6.16.9 kernel.
It allows a task to read usage information about another task. The argument
who can be equal to RUSAGE_SELF, to RUSAGE_CHILDREN or to a valid pid.
The permissions are checked through security_ptrace() as suggested by Andy.
Any other comment ?
Thanks,
Claudio
Signed-off-by: Claudio Scordino <[email protected]>
--- sys.old.c 2006-04-19 02:10:14.000000000 -0400
+++ sys.c 2006-04-20 10:53:16.000000000 -0400
@@ -1765,11 +1765,30 @@ int getrusage(struct task_struct *p, int
return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
}
+/* who can be RUSAGE_SELF, RUSAGE_CHILDREN or a valid pid */
asmlinkage long sys_getrusage(int who, struct rusage __user *ru)
{
- if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
- return -EINVAL;
- return getrusage(current, who, ru);
+ struct rusage r;
+ struct task_struct* tsk = current;
+ read_lock(&tasklist_lock);
+ if ((who != RUSAGE_SELF) && (who != RUSAGE_CHILDREN)) {
+ if (who <= 0)
+ goto bad;
+ tsk = find_task_by_pid(who);
+ if (tsk == NULL)
+ goto bad;
+ if ((tsk != current) && security_ptrace(current, tsk))
+ goto bad;
+ /* current can get info about tsk */
+ who = RUSAGE_SELF;
+ }
+ k_getrusage(tsk, who, &r);
+ read_unlock(&tasklist_lock);
+ return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
+
+bad:
+ read_unlock(&tasklist_lock);
+ return tsk ? -EPERM : -EINVAL;
}
asmlinkage long sys_umask(int mask)
-
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