Re: [PATCH 17/18] nvmet-tcp: control messages for recvmsg()

[Sagi Grimberg <sagi@grimberg.me>]

On 3/29/23 16:59, Hannes Reinecke wrote:
> kTLS requires control messages for recvmsg() to relay any out-of-band
> TLS messages (eg TLS alerts) to the caller.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
>   drivers/nvme/target/tcp.c | 71 +++++++++++++++++++++++++++++++++++++++
>   1 file changed, 71 insertions(+)
> 
> diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
> index 5daf16138471..75017fd5da9f 100644
> --- a/drivers/nvme/target/tcp.c
> +++ b/drivers/nvme/target/tcp.c
> @@ -12,6 +12,7 @@
>   #include <net/sock.h>
>   #include <net/tcp.h>
>   #ifdef CONFIG_NVME_TLS
> +#include <net/tls.h>
>   #include <net/handshake.h>
>   #include <linux/nvme-keyring.h>
>   #endif
> @@ -92,6 +93,7 @@ struct nvmet_tcp_cmd {
>   	u32				pdu_len;
>   	u32				pdu_recv;
>   	int				sg_idx;
> +	char				recv_cbuf[CMSG_LEN(sizeof(char))];
>   	struct msghdr			recv_msg;
>   	struct bio_vec			*iov;
>   	u32				flags;
> @@ -1086,7 +1088,18 @@ static int nvmet_tcp_try_recv_pdu(struct nvmet_tcp_queue *queue)
>   	struct nvme_tcp_hdr *hdr = &queue->pdu.cmd.hdr;
>   	int len;
>   	struct kvec iov;
> +#ifdef CONFIG_NVME_TLS

Do you need this ifdef? The recv_cbuf in the cmd is not under and ifdef.

> +	char cbuf[CMSG_LEN(sizeof(char))] = {};
> +	unsigned char ctype;
> +	struct cmsghdr *cmsg;
> +	struct msghdr msg = {
> +		.msg_control = cbuf,
> +		.msg_controllen = sizeof(cbuf),
> +		.msg_flags = MSG_DONTWAIT
> +	};
> +#else
>   	struct msghdr msg = { .msg_flags = MSG_DONTWAIT };
> +#endif
>   
>   recv:
>   	iov.iov_base = (void *)&queue->pdu + queue->offset;
> @@ -1095,6 +1108,19 @@ static int nvmet_tcp_try_recv_pdu(struct nvmet_tcp_queue *queue)
>   			iov.iov_len, msg.msg_flags);
>   	if (unlikely(len < 0))
>   		return len;
> +#ifdef CONFIG_NVME_TLS
> +	cmsg = (struct cmsghdr *)cbuf;
> +	if (CMSG_OK(&msg, cmsg) &&
> +	    cmsg->cmsg_level == SOL_TLS &&
> +	    cmsg->cmsg_type == TLS_GET_RECORD_TYPE) {
> +		ctype = *((unsigned char *)CMSG_DATA(cmsg));
> +		if (ctype != TLS_RECORD_TYPE_DATA) {
> +			pr_err("queue %d unhandled TLS record %d\n",
> +				queue->idx, ctype);
> +			return -ENOTCONN;
> +		}
> +	}
> +#endif

Can we consolidate this to a helper?

Something like:
static int nvmet_tcp_check_cmsg(struct nvmet_tcp_queue *queue, struct 
cmsghdr *cmsg)
{
	if (!IS_ENABLED(CONFIG_NVME_TLS))
		return 0;

	if (CMSG_OK(&msg, cmsg) &&
	    cmsg->cmsg_level == SOL_TLS &&
	    cmsg->cmsg_type == TLS_GET_RECORD_TYPE) {
		ctype = *((unsigned char *)CMSG_DATA(cmsg));
		if (ctype != TLS_RECORD_TYPE_DATA) {
			pr_err("queue %d unhandled TLS record %d\n",
				queue->idx, ctype);
			return -ENOTCONN;
		}
	}
	return 0;
}

>   
>   	queue->offset += len;
>   	queue->left -= len;
> @@ -1150,10 +1176,27 @@ static int nvmet_tcp_try_recv_data(struct nvmet_tcp_queue *queue)
>   	int ret;
>   
>   	while (msg_data_left(&cmd->recv_msg)) {
> +#ifdef CONFIG_NVME_TLS
> +		struct cmsghdr *cmsg;
> +		unsigned char ctype;
> +#endif
>   		ret = sock_recvmsg(cmd->queue->sock, &cmd->recv_msg,
>   			cmd->recv_msg.msg_flags);
>   		if (ret <= 0)
>   			return ret;
> +#ifdef CONFIG_NVME_TLS
> +		cmsg = (struct cmsghdr *)cmd->recv_cbuf;
> +		if (CMSG_OK(&cmd->recv_msg, cmsg) &&
> +		    cmsg->cmsg_level == SOL_TLS &&
> +		    cmsg->cmsg_type == TLS_GET_RECORD_TYPE) {
> +			ctype = *((unsigned char *)CMSG_DATA(cmsg));
> +			if (ctype != TLS_RECORD_TYPE_DATA) {
> +				pr_err("queue %d unhandled TLS record %d\n",
> +				       queue->idx, ctype);
> +				return -ENOTCONN;
> +			}
> +		}
> +#endif
>   
>   		cmd->pdu_recv += ret;
>   		cmd->rbytes_done += ret;
> @@ -1175,7 +1218,18 @@ static int nvmet_tcp_try_recv_ddgst(struct nvmet_tcp_queue *queue)
>   {
>   	struct nvmet_tcp_cmd *cmd = queue->cmd;
>   	int ret;
> +#ifdef CONFIG_NVME_TLS
> +	char cbuf[CMSG_LEN(sizeof(char))] = {};
> +	unsigned char ctype;
> +	struct cmsghdr *cmsg;
> +	struct msghdr msg = {
> +		.msg_control = cbuf,
> +		.msg_controllen = sizeof(cbuf),
> +		.msg_flags = MSG_DONTWAIT
> +	};
> +#else
>   	struct msghdr msg = { .msg_flags = MSG_DONTWAIT };
> +#endif
>   	struct kvec iov = {
>   		.iov_base = (void *)&cmd->recv_ddgst + queue->offset,
>   		.iov_len = queue->left
> @@ -1185,6 +1239,19 @@ static int nvmet_tcp_try_recv_ddgst(struct nvmet_tcp_queue *queue)
>   			iov.iov_len, msg.msg_flags);
>   	if (unlikely(ret < 0))
>   		return ret;
> +#ifdef CONFIG_NVME_TLS
> +	cmsg = (struct cmsghdr *)cbuf;
> +	if (CMSG_OK(&msg, cmsg) &&
> +	    cmsg->cmsg_level == SOL_TLS &&
> +	    cmsg->cmsg_type == TLS_GET_RECORD_TYPE) {
> +		ctype = *((unsigned char *)CMSG_DATA(cmsg));
> +		if (ctype != TLS_RECORD_TYPE_DATA) {
> +			pr_err("queue %d unhandled TLS record %d\n",
> +				queue->idx, ctype);
> +			return -ENOTCONN;
> +		}
> +	}
> +#endif
>   
>   	queue->offset += ret;
>   	queue->left -= ret;
> @@ -1354,6 +1421,10 @@ static int nvmet_tcp_alloc_cmd(struct nvmet_tcp_queue *queue,
>   	if (!c->r2t_pdu)
>   		goto out_free_data;
>   
> +#ifdef CONFIG_NVME_TLS
> +	c->recv_msg.msg_control = c->recv_cbuf;
> +	c->recv_msg.msg_controllen = sizeof(c->recv_cbuf);
> +#endif
>   	c->recv_msg.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
>   
>   	list_add_tail(&c->entry, &queue->free_list);