Re: [PATCH net-next] tuntap: add sanity checks about msg_controllen in sendmsg

[Jason Wang <jasowang@xxxxxxxxxx>]

在 2022/3/3 上午10:24, Harold Huang 写道:
> In patch [1], tun_msg_ctl was added to allow pass batched xdp buffers to
> tun_sendmsg. Although we donot use msg_controllen in this path, we should
> check msg_controllen to make sure the caller pass a valid msg_ctl.
>
> [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fe8dd45bb7556246c6b76277b1ba4296c91c2505
>
> Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
> Signed-off-by: Harold Huang <baymaxhuang@xxxxxxxxx>


Acked-by: Jason Wang <jasowang@xxxxxxxxxx>


> ---
>   drivers/net/tap.c   | 3 ++-
>   drivers/net/tun.c   | 3 ++-
>   drivers/vhost/net.c | 1 +
>   3 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/tap.c b/drivers/net/tap.c
> index 8e3a28ba6b28..ba2ef5437e16 100644
> --- a/drivers/net/tap.c
> +++ b/drivers/net/tap.c
> @@ -1198,7 +1198,8 @@ static int tap_sendmsg(struct socket *sock, struct msghdr *m,
>   	struct xdp_buff *xdp;
>   	int i;
>   
> -	if (ctl && (ctl->type == TUN_MSG_PTR)) {
> +	if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
> +	    ctl && ctl->type == TUN_MSG_PTR) {
>   		for (i = 0; i < ctl->num; i++) {
>   			xdp = &((struct xdp_buff *)ctl->ptr)[i];
>   			tap_get_user_xdp(q, xdp);
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 969ea69fd29d..2a0d8a5d7aec 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -2501,7 +2501,8 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
>   	if (!tun)
>   		return -EBADFD;
>   
> -	if (ctl && (ctl->type == TUN_MSG_PTR)) {
> +	if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
> +	    ctl && ctl->type == TUN_MSG_PTR) {
>   		struct tun_page tpage;
>   		int n = ctl->num;
>   		int flush = 0, queued = 0;
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 28ef323882fb..792ab5f23647 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -473,6 +473,7 @@ static void vhost_tx_batch(struct vhost_net *net,
>   		goto signal_used;
>   
>   	msghdr->msg_control = &ctl;
> +	msghdr->msg_controllen = sizeof(ctl);
>   	err = sock->ops->sendmsg(sock, msghdr, 0);
>   	if (unlikely(err < 0)) {
>   		vq_err(&nvq->vq, "Fail to batch sending packets\n");