On Sat, Sep 22, 2018 at 11:53:14AM +0200, Thomas Gleixner wrote:
> @@ -86,6 +88,7 @@ extern void exit_ptrace(struct task_stru
> * process_vm_writev or ptrace (and should use the real credentials).
> */
> extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
> +extern bool ptrace_may_access_sched(struct task_struct *task, unsigned int
> mode);
I like that..
> static inline int ptrace_reparented(struct task_struct *child)
> {
> --- a/kernel/ptrace.c
> +++ b/kernel/ptrace.c
> +bool ptrace_may_access_sched(struct task_struct *task, unsigned int mode)
> +{
> + struct mm_struct *mm;
> + int res;
> +
> + res = __ptrace_may_access_basic(task, mode);
> + if (res <= 0)
> + return !res;
> +
> + rcu_read_lock();
> + res = __ptrace_may_access_cred(__task_cred(task), mode);
> rcu_read_unlock();
> + if (res)
> + return false;
> +
> + mm = task->mm;
> + if (mm && get_dumpable(mm) != SUID_DUMP_USER)
> + return false;
> + return true;
> +}
> +
> +/* Returns 0 on success, -errno on denial. */
> +static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
> +{
> + const struct cred *tcred;
> + struct mm_struct *mm;
> + int res;
> +
> + res = __ptrace_may_access_basic(task, mode);
> + if (res <= 0)
> + return res;
> +
> + rcu_read_lock();
> + tcred = __task_cred(task);
> + res = __ptrace_may_access_cred(tcred, mode);
> + if (res > 0)
> + res = ptrace_has_cap(tcred->user_ns, mode) ? 0 : -EPERM;
> rcu_read_unlock();
> + if (res < 0)
> + return res;
> +
> mm = task->mm;
> + if (mm && (get_dumpable(mm) != SUID_DUMP_USER &&
> + !ptrace_has_cap(mm->user_ns, mode)))
> + return -EPERM;
>
> return security_ptrace_access_check(task, mode);
> }
This has some unfortunate duplication.
Lets go with it for now, but I'll see if I can do something about that
later.
