C++ cap_issubset函数代码示例

int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
		      kernel_cap_t *inheritable, kernel_cap_t *permitted)
{
	/* Derived from kernel/capability.c:sys_capset. */
	/* verify restrictions on target's new Inheritable set */
	if (!cap_issubset (*inheritable,
			   cap_combine (target->cap_inheritable,
					current->cap_permitted))) {
		return -EPERM;
	}

	/* verify restrictions on target's new Permitted set */
	if (!cap_issubset (*permitted,
			   cap_combine (target->cap_permitted,
					current->cap_permitted))) {
		return -EPERM;
	}

	/* verify the _new_Effective_ is a subset of the _new_Permitted_ */
	if (!cap_issubset (*effective, *permitted)) {
		return -EPERM;
	}

	return 0;
}

int cap_ptrace (struct task_struct *parent, struct task_struct *child)
{
	/* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
	if (!cap_issubset(child->cap_permitted, parent->cap_permitted) &&
	    !__capable(parent, CAP_SYS_PTRACE))
		return -EPERM;
	return 0;
}

/**
 * cap_ptrace_traceme - Determine whether another process may trace the current
 * @parent: The task proposed to be the tracer
 *
 * Determine whether the nominated task is permitted to trace the current
 * process, returning 0 if permission is granted, -ve if denied.
 */
int cap_ptrace_traceme(struct task_struct *parent)
{
	int ret = 0;

	rcu_read_lock();
	if (!cap_issubset(current_cred()->cap_permitted,
			  __task_cred(parent)->cap_permitted) &&
	    !has_capability(parent, CAP_SYS_PTRACE))
		ret = -EPERM;
	rcu_read_unlock();
	return ret;
}

/**
 * cap_ptrace_access_check - Determine whether the current process may access
 *			   another
 * @child: The process to be accessed
 * @mode: The mode of attachment.
 *
 * Determine whether a process may access another, returning 0 if permission
 * granted, -ve if denied.
 */
int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
{
	int ret = 0;

	rcu_read_lock();
	if (!cap_issubset(__task_cred(child)->cap_permitted,
			  current_cred()->cap_permitted) &&
	    !capable(CAP_SYS_PTRACE))
		ret = -EPERM;
	rcu_read_unlock();
	return ret;
}

int ptrace_attach(struct task_struct *task)
{
	task_lock(task);
	if (task->pid <= 1)
		goto bad;
	if (task == current)
		goto bad;
	if (!task->mm)
		goto bad;
	if(((current->uid != task->euid) ||
	    (current->uid != task->suid) ||
	    (current->uid != task->uid) ||
 	    (current->gid != task->egid) ||
 	    (current->gid != task->sgid) ||
 	    (!cap_issubset(task->cap_permitted, current->cap_permitted)) ||
 	    (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
		goto bad;
	rmb();
	if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
		goto bad;
	/* the same process cannot be attached many times */
	if (task->ptrace & PT_PTRACED)
		goto bad;

	/* Go */
	task->ptrace |= PT_PTRACED;
	if (capable(CAP_SYS_PTRACE))
		task->ptrace |= PT_PTRACE_CAP;
	task_unlock(task);

	write_lock_irq(&tasklist_lock);
	if (task->p_pptr != current) {
		REMOVE_LINKS(task);
		task->p_pptr = current;
		SET_LINKS(task);
	}
	write_unlock_irq(&tasklist_lock);

	send_sig(SIGSTOP, task, 1);
	return 0;

bad:
	task_unlock(task);
	return -EPERM;
}

void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
{
	/* Derived from fs/exec.c:compute_creds. */
	kernel_cap_t new_permitted, working;

	new_permitted = cap_intersect (bprm->cap_permitted, cap_bset);
	working = cap_intersect (bprm->cap_inheritable,
				 current->cap_inheritable);
	new_permitted = cap_combine (new_permitted, working);

	if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
	    !cap_issubset (new_permitted, current->cap_permitted)) {
		current->mm->dumpable = 0;

		if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
			if (!capable(CAP_SETUID)) {
				bprm->e_uid = current->uid;
				bprm->e_gid = current->gid;
			}
			if (!capable (CAP_SETPCAP)) {
				new_permitted = cap_intersect (new_permitted,
							current->cap_permitted);
			}
		}
	}

	current->suid = current->euid = current->fsuid = bprm->e_uid;
	current->sgid = current->egid = current->fsgid = bprm->e_gid;

	/* For init, we want to retain the capabilities set
	 * in the init_task struct. Thus we skip the usual
	 * capability rules */
	if (current->pid != 1) {
		current->cap_permitted = new_permitted;
		current->cap_effective =
		    cap_intersect (new_permitted, bprm->cap_effective);
	}

	/* AUD: Audit candidate if current->cap_effective is set */

	current->keep_capabilities = 0;
}

/**
 * cap_ptrace_access_check - Determine whether the current process may access
 *			   another
 * @child: The process to be accessed
 * @mode: The mode of attachment.
 *
 * If we are in the same or an ancestor user_ns and have all the target
 * task's capabilities, then ptrace access is allowed.
 * If we have the ptrace capability to the target user_ns, then ptrace
 * access is allowed.
 * Else denied.
 *
 * Determine whether a process may access another, returning 0 if permission
 * granted, -ve if denied.
 */
int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
{
	int ret = 0;
	const struct cred *cred, *child_cred;
	const kernel_cap_t *caller_caps;

	rcu_read_lock();
	cred = current_cred();
	child_cred = __task_cred(child);
	if (mode & PTRACE_MODE_FSCREDS)
		caller_caps = &cred->cap_effective;
	else
		caller_caps = &cred->cap_permitted;
	if (cred->user_ns == child_cred->user_ns &&
	    cap_issubset(child_cred->cap_permitted, *caller_caps))
		goto out;
	if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE))
		goto out;
	ret = -EPERM;
out:
	rcu_read_unlock();
	return ret;
}

long sys_ptrace(long request, pid_t pid, long addr, long data)
{
	struct task_struct *child;
	long ret;

	lock_kernel();
	ret = -EPERM;
	if (request == PTRACE_TRACEME) {
		/* are we already being traced? */
		if (current->ptrace & PT_PTRACED)
			goto out;
		/* set the ptrace bit in the process flags. */
		current->ptrace |= PT_PTRACED;
		ret = 0;
		goto out;
	}

	ret = -ESRCH;
	read_lock(&tasklist_lock);
	child = find_task_by_pid(pid);
	if (child)
		get_task_struct(child);
	read_unlock(&tasklist_lock);
	if (!child)
		goto out;
	ret = -EPERM;
	if (pid == 1)		/* no messing around with init! */
		goto out_tsk;

	if (request == PTRACE_ATTACH) {
		if (child == current)
			goto out_tsk;
		if ((!child->dumpable ||
		    (current->uid != child->euid) ||
		    (current->uid != child->suid) ||
		    (current->uid != child->uid) ||
	 	    (current->gid != child->egid) ||
	 	    (current->gid != child->sgid) ||
	 	    (!cap_issubset(child->cap_permitted, current->cap_permitted)) ||
	 	    (current->gid != child->gid)) && !capable(CAP_SYS_PTRACE))
			goto out_tsk;
		/* the same process cannot be attached many times */
		if (child->ptrace & PT_PTRACED)
			goto out_tsk;
		child->ptrace |= PT_PTRACED;
		if (child->p_pptr != current) {
			unsigned long flags;

			write_lock_irqsave(&tasklist_lock, flags);
			REMOVE_LINKS(child);
			child->p_pptr = current;
			SET_LINKS(child);
			write_unlock_irqrestore(&tasklist_lock, flags);
		}
		send_sig(SIGSTOP, child, 1);
		ret = 0;
		goto out_tsk;
	}
	ret = -ESRCH;
	if (!(child->ptrace & PT_PTRACED))
		goto out_tsk;
	if (child->state != TASK_STOPPED) {
		if (request != PTRACE_KILL)
			goto out_tsk;
	}
	if (child->p_pptr != current)
		goto out_tsk;

	switch (request) {
	case PTRACE_PEEKTEXT: /* read word at location addr. */ 
	case PTRACE_PEEKDATA: {
		unsigned long tmp;
		int copied;

		copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
		ret = -EIO;
		if (copied != sizeof(tmp))
			goto out_tsk;
		ret = put_user(tmp,(unsigned long *) data);
		goto out_tsk;
	}

	/* when I and D space are separate, this will have to be fixed. */
	case PTRACE_POKETEXT: /* write the word at location addr. */
	case PTRACE_POKEDATA:
		ret = 0;
		if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
			goto out_tsk;
		ret = -EIO;
		goto out_tsk;

	/* Read the word at location addr in the USER area.  This will need
	   to change when the kernel no longer saves all regs on a syscall. */
	case PTRACE_PEEKUSR: {
		unsigned long tmp;

		ret = -EIO;
		if ((addr & 3) || (unsigned long) addr >= sizeof(struct pt_regs))
			goto out_tsk;

//.........这里部分代码省略.........

static int krg_set_cap(struct task_struct *tsk,
		       const kernel_krg_cap_t *requested_cap)
{
	kernel_krg_cap_t *caps = &tsk->krg_caps;
	kernel_cap_t tmp_cap;
	struct nsproxy *nsp;
	int res;
	int i;

	res = 0;
	rcu_read_lock();
	nsp = rcu_dereference(tsk->nsproxy);
	if (!nsp || !nsp->krg_ns)
		res = -EPERM;
	rcu_read_unlock();
	if (res)
		goto out;

	res = -EINVAL;
	if (!cap_issubset(requested_cap->effective, requested_cap->permitted)
	    || !cap_issubset(requested_cap->inheritable_permitted,
			     requested_cap->permitted)
	    || !cap_issubset(requested_cap->inheritable_effective,
			     requested_cap->inheritable_permitted))
		goto out;

	res = -ENOSYS;
	tmp_cap = KRG_CAP_SUPPORTED;
	if (!cap_issubset(requested_cap->permitted, tmp_cap))
		goto out;

	res = -EPERM;
	if (!permissions_ok(tsk))
		goto out;

	task_lock(tsk);

	if (!cap_raised(caps->effective, CAP_CHANGE_KERRIGHED_CAP))
		goto out_unlock;

	res = -EBUSY;
	for (i = 0; i < CAP_SIZE; i++)
		if (atomic_read(&tsk->krg_cap_used[i])
		    && !cap_raised(requested_cap->effective, i))
			goto out_unlock;

	tmp_cap = cap_intersect(caps->permitted, requested_cap->permitted);
	caps->permitted = tmp_cap;
	tmp_cap = cap_intersect(caps->permitted, requested_cap->effective);
	caps->effective = tmp_cap;
	tmp_cap = cap_intersect(caps->permitted,
				requested_cap->inheritable_effective);
	caps->inheritable_effective = tmp_cap;
	tmp_cap = cap_intersect(caps->permitted,
				requested_cap->inheritable_permitted);
	caps->inheritable_permitted = tmp_cap;

	res = 0;

out_unlock:
	task_unlock(tsk);

out:
	return res;
}