BUG_ON(!list_empty(&child->ptrace_entry));
list_add(&child->ptrace_entry, &new_parent->ptraced);
child->parent = new_parent;
+ rcu_read_lock();
+ child->ptracer_cred = get_cred(__task_cred(new_parent));
+ rcu_read_unlock();
}
/**
*/
void __ptrace_unlink(struct task_struct *child)
{
+ const struct cred *old_cred;
BUG_ON(!child->ptrace);
child->ptrace = 0;
child->parent = child->real_parent;
list_del_init(&child->ptrace_entry);
+ old_cred = child->ptracer_cred;
+ child->ptracer_cred = NULL;
+ put_cred(old_cred);
spin_lock(&child->sighand->siglock);
static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
{
const struct cred *cred = current_cred(), *tcred;
+ struct mm_struct *mm;
+ kuid_t caller_uid;
+ kgid_t caller_gid;
+
+ if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) {
+ WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n");
+ return -EPERM;
+ }
/* May we inspect the given task?
* This check is used both for attaching with ptrace
* because setting up the necessary parent/child relationship
* or halting the specified task is impossible.
*/
- int dumpable = 0;
+
/* Don't let security modules deny introspection */
if (same_thread_group(task, current))
return 0;
rcu_read_lock();
+ if (mode & PTRACE_MODE_FSCREDS) {
+ caller_uid = cred->fsuid;
+ caller_gid = cred->fsgid;
+ } else {
+ /*
+ * Using the euid would make more sense here, but something
+ * in userland might rely on the old behavior, and this
+ * shouldn't be a security problem since
+ * PTRACE_MODE_REALCREDS implies that the caller explicitly
+ * used a syscall that requests access to another process
+ * (and not a filesystem syscall to procfs).
+ */
+ caller_uid = cred->uid;
+ caller_gid = cred->gid;
+ }
tcred = __task_cred(task);
- if (uid_eq(cred->uid, tcred->euid) &&
- uid_eq(cred->uid, tcred->suid) &&
- uid_eq(cred->uid, tcred->uid) &&
- gid_eq(cred->gid, tcred->egid) &&
- gid_eq(cred->gid, tcred->sgid) &&
- gid_eq(cred->gid, tcred->gid))
+ if (uid_eq(caller_uid, tcred->euid) &&
+ uid_eq(caller_uid, tcred->suid) &&
+ uid_eq(caller_uid, tcred->uid) &&
+ gid_eq(caller_gid, tcred->egid) &&
+ gid_eq(caller_gid, tcred->sgid) &&
+ gid_eq(caller_gid, tcred->gid))
goto ok;
if (ptrace_has_cap(tcred->user_ns, mode))
goto ok;
return -EPERM;
ok:
rcu_read_unlock();
- smp_rmb();
- if (task->mm)
- dumpable = get_dumpable(task->mm);
- rcu_read_lock();
- if (dumpable != SUID_DUMP_USER &&
- !ptrace_has_cap(__task_cred(task)->user_ns, mode)) {
- rcu_read_unlock();
- return -EPERM;
- }
- rcu_read_unlock();
+ 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);
}
goto out;
task_lock(task);
- retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
+ retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS);
task_unlock(task);
if (retval)
goto unlock_creds;
if (seize)
flags |= PT_SEIZED;
- rcu_read_lock();
- if (ns_capable(__task_cred(task)->user_ns, CAP_SYS_PTRACE))
- flags |= PT_PTRACE_CAP;
- rcu_read_unlock();
task->ptrace = flags;
__ptrace_link(task, current);