[PATCHv5 1/1] nvme-tcp: Add option to set the physical interface to be used when connecting over TCP sockets.
Sagi Grimberg
sagi at grimberg.me
Fri May 14 10:45:41 PDT 2021
On 5/14/21 4:46 AM, Martin Belanger wrote:
> From: Martin Belanger <martin.belanger at dell.com>
>
> Addressed reviews from PATCHv4.
>
> In our application, we need a way to force TCP connections to go out a
> specific IP interface instead of letting Linux select the interface
> based on the routing tables. This patch adds the option 'host-iface'
> to allow specifying the interface to use. Note that corresponding
> changes to the nvme-cli utility will follow.
>
> When the option host-iface is specified, the driver uses the specified
> interface to set the option SO_BINDTODEVICE on the TCP socket before
> connecting.
>
> This new option is needed in addtion to the existing host-traddr for
> the following reasons:
>
> Specifying an IP interface by its associated IP address is less
> intuitive than specifying the actual interface name and, in some cases,
> simply doesn't work. That's because the association between interfaces
> and IP addresses is not predictable. IP addresses can be changed or can
> change by themselves over time (e.g. DHCP). Interface names are
> predictable [1] and will persist over time. Consider the following
> configuration.
>
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state ...
> link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> inet 100.0.0.100/24 scope global lo
> valid_lft forever preferred_lft forever
> 2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc ...
> link/ether 08:00:27:21:65:ec brd ff:ff:ff:ff:ff:ff
> inet 100.0.0.100/24 scope global enp0s3
> valid_lft forever preferred_lft forever
> 3: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc ...
> link/ether 08:00:27:4f:95:5c brd ff:ff:ff:ff:ff:ff
> inet 100.0.0.100/24 scope global enp0s8
> valid_lft forever preferred_lft forever
>
> The above is a VM that I configured with the same IP address
> (100.0.0.100) on all interfaces. Doing a reverse lookup to identify the
> unique interface associated with 100.0.0.100 does not work here. And
> this is why the option host_iface is required. I understand that the
> above config does not represent a standard host system, but I'm using
> this to prove a point: "We can never know how users will configure
> their systems". By te way, The above configuration is perfectly fine
> by Linux.
>
> The current TCP implementation for host_traddr performs a
> bind()-before-connect(). This is a common construct to set the source
> IP address on a TCP socket before connecting. This has no effect on how
> Linux selects the interface for the connection. That's because Linux
> uses the Weak End System model as described in RFC1122 [2]. On the other
> hand, setting the Source IP Address has benefits and should be supported
> by linux-nvme. In fact, setting the Source IP Address is a mandatory
> FedGov requirement (e.g. connection to a RADIUS/TACACS+ server).
> Consider the following configuration.
>
> $ ip addr list dev enp0s8
> 3: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc ...
> link/ether 08:00:27:4f:95:5c brd ff:ff:ff:ff:ff:ff
> inet 192.168.56.101/24 brd 192.168.56.255 scope global enp0s8
> valid_lft 426sec preferred_lft 426sec
> inet 192.168.56.102/24 scope global secondary enp0s8
> valid_lft forever preferred_lft forever
> inet 192.168.56.103/24 scope global secondary enp0s8
> valid_lft forever preferred_lft forever
> inet 192.168.56.104/24 scope global secondary enp0s8
> valid_lft forever preferred_lft forever
>
> Here we can see that several addresses are associated with interface
> enp0s8. By default, Linux always selects the default IP address,
> 192.168.56.101, as the source address when connecting over interface
> enp0s8. Some users, however, want the ability to specify a different
> source address (e.g., 192.168.56.102, 192.168.56.103, ...). The option
> host_traddr can be used as-is to perform this function.
>
> In conclusion, I believe that we need 2 options for TCP connections.
> One that can be used to specify an interface (host-iface). And one that
> can be used to set the source address (host-traddr). Users should be
> allowed to use one or the other, or both, or none. Of course, the
> documentation for host_traddr will need some clarification. It should
> state that when used for TCP connection, this option only sets the
> source address. And the documentation for host_iface should say that
> this option is only available for TCP connections.
>
> References:
> [1] https://www.freedesktop.org/wiki/Software/systemd/\
> PredictableNetworkInterfaceNames/
> [2] https://tools.ietf.org/html/rfc1122
>
> Tested both IPv4 and IPv6 connections.
>
> Signed-off-by: Martin Belanger <martin.belanger at dell.com>
> ---
> drivers/nvme/host/core.c | 5 ++++
> drivers/nvme/host/fabrics.c | 14 +++++++++++
> drivers/nvme/host/fabrics.h | 6 ++++-
> drivers/nvme/host/tcp.c | 48 ++++++++++++++++++++++++++++++++++++-
> 4 files changed, 71 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 762125f2905f..f98255eb7deb 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -4067,6 +4067,11 @@ static int nvme_class_uevent(struct device *dev, struct kobj_uevent_env *env)
>
> ret = add_uevent_var(env, "NVME_HOST_TRADDR=%s",
> opts->host_traddr ?: "none");
> + if (ret)
> + return ret;
> +
> + ret = add_uevent_var(env, "NVME_HOST_IFACE=%s",
> + opts->host_iface ?: "none");
> }
> return ret;
> }
> diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
> index a2bb7fc63a73..76dc3eaf46f3 100644
> --- a/drivers/nvme/host/fabrics.c
> +++ b/drivers/nvme/host/fabrics.c
> @@ -112,6 +112,9 @@ int nvmf_get_address(struct nvme_ctrl *ctrl, char *buf, int size)
> if (ctrl->opts->mask & NVMF_OPT_HOST_TRADDR)
> len += scnprintf(buf + len, size - len, "%shost_traddr=%s",
> (len) ? "," : "", ctrl->opts->host_traddr);
> + if (ctrl->opts->mask & NVMF_OPT_HOST_IFACE)
> + len += scnprintf(buf + len, size - len, "%shost_iface=%s",
> + (len) ? "," : "", ctrl->opts->host_iface);
> len += scnprintf(buf + len, size - len, "\n");
>
> return len;
> @@ -545,6 +548,7 @@ static const match_table_t opt_tokens = {
> { NVMF_OPT_KATO, "keep_alive_tmo=%d" },
> { NVMF_OPT_HOSTNQN, "hostnqn=%s" },
> { NVMF_OPT_HOST_TRADDR, "host_traddr=%s" },
> + { NVMF_OPT_HOST_IFACE, "host_iface=%s" },
> { NVMF_OPT_HOST_ID, "hostid=%s" },
> { NVMF_OPT_DUP_CONNECT, "duplicate_connect" },
> { NVMF_OPT_DISABLE_SQFLOW, "disable_sqflow" },
> @@ -754,6 +758,15 @@ static int nvmf_parse_options(struct nvmf_ctrl_options *opts,
> kfree(opts->host_traddr);
> opts->host_traddr = p;
> break;
> + case NVMF_OPT_HOST_IFACE:
> + p = match_strdup(args);
> + if (!p) {
> + ret = -ENOMEM;
> + goto out;
> + }
> + kfree(opts->host_iface);
> + opts->host_iface = p;
> + break;
> case NVMF_OPT_HOST_ID:
> p = match_strdup(args);
> if (!p) {
> @@ -938,6 +951,7 @@ void nvmf_free_options(struct nvmf_ctrl_options *opts)
> kfree(opts->trsvcid);
> kfree(opts->subsysnqn);
> kfree(opts->host_traddr);
> + kfree(opts->host_iface);
> kfree(opts);
> }
> EXPORT_SYMBOL_GPL(nvmf_free_options);
> diff --git a/drivers/nvme/host/fabrics.h b/drivers/nvme/host/fabrics.h
> index d7f7974dc208..c31dad69a773 100644
> --- a/drivers/nvme/host/fabrics.h
> +++ b/drivers/nvme/host/fabrics.h
> @@ -66,6 +66,7 @@ enum {
> NVMF_OPT_NR_POLL_QUEUES = 1 << 18,
> NVMF_OPT_TOS = 1 << 19,
> NVMF_OPT_FAIL_FAST_TMO = 1 << 20,
> + NVMF_OPT_HOST_IFACE = 1 << 21,
> };
>
> /**
> @@ -83,7 +84,9 @@ enum {
> * @trsvcid: The transport-specific TRSVCID field for a port on the
> * subsystem which is adding a controller.
> * @host_traddr: A transport-specific field identifying the NVME host port
> - * to use for the connection to the controller.
> + * to use for the connection to the controller.
> + * @host_iface: A transport-specific field identifying the NVME host
> + * interface to use for the connection to the controller.
> * @queue_size: Number of IO queue elements.
> * @nr_io_queues: Number of controller IO queues that will be established.
> * @reconnect_delay: Time between two consecutive reconnect attempts.
> @@ -108,6 +111,7 @@ struct nvmf_ctrl_options {
> char *traddr;
> char *trsvcid;
> char *host_traddr;
> + char *host_iface;
> size_t queue_size;
> unsigned int nr_io_queues;
> unsigned int reconnect_delay;
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index 0222e23f5936..32e44527afaa 100644
> --- a/drivers/nvme/host/tcp.c
> +++ b/drivers/nvme/host/tcp.c
> @@ -123,6 +123,7 @@ struct nvme_tcp_ctrl {
> struct blk_mq_tag_set admin_tag_set;
> struct sockaddr_storage addr;
> struct sockaddr_storage src_addr;
> + struct net_device *ndev;
> struct nvme_ctrl ctrl;
>
> struct work_struct err_work;
> @@ -1454,6 +1455,20 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl,
> }
> }
>
> + if (nctrl->opts->mask & NVMF_OPT_HOST_IFACE) {
> + char *iface = nctrl->opts->host_iface;
> + sockptr_t optval = KERNEL_SOCKPTR(iface);
> +
> + ret = sock_setsockopt(queue->sock, SOL_SOCKET, SO_BINDTODEVICE,
> + optval, strlen(iface));
> + if (ret) {
> + dev_err(nctrl->device,
> + "failed to bind to interface %s queue %d err %d\n",
> + iface, qid, ret);
> + goto err_sock;
> + }
> + }
> +
> queue->hdr_digest = nctrl->opts->hdr_digest;
> queue->data_digest = nctrl->opts->data_digest;
> if (queue->hdr_digest || queue->data_digest) {
> @@ -2514,6 +2529,37 @@ static struct nvme_ctrl *nvme_tcp_create_ctrl(struct device *dev,
> }
> }
>
> + if (opts->mask & NVMF_OPT_HOST_IFACE) {
> + ctrl->ndev = dev_get_by_name(&init_net, opts->host_iface);
> + if (!ctrl->ndev) {
> + pr_err("invalid interface passed: %s\n",
> + opts->host_iface);
> + ret = -ENODEV;
> + goto out_free_ctrl;
> + }
> + }
> +
> + /* For IPv6 HOST_TRADDR, check if scope ID is specified. If not, set
> + * HOST_TRADDR's scope ID to the scope ID of HOST_IFACE or the scope
> + * ID of TRADDR
> + */
Not sure I follow what this is doing. the binding is taken from either
host_traddr, host_iface or traddr? What are the rules here?
> + if ((opts->mask & NVMF_OPT_HOST_TRADDR) &&
> + (ctrl->src_addr.ss_family == AF_INET6)) {
> + struct sockaddr_in6 *src_addr6 =
> + (struct sockaddr_in6 *)&ctrl->src_addr;
> +
> + if (src_addr6->sin6_scope_id == 0) {
> + if (ctrl->ndev && (ctrl->ndev->ifindex != 0)) {
> + src_addr6->sin6_scope_id = ctrl->ndev->ifindex;
> + } else {
> + struct sockaddr_in6 *addr6 =
> + (struct sockaddr_in6 *)&ctrl->addr;
> +
> + src_addr6->sin6_scope_id = addr6->sin6_scope_id;
> + }
> + }
> + }
> +
> if (!opts->duplicate_connect && nvme_tcp_existing_controller(opts)) {
> ret = -EALREADY;
> goto out_free_ctrl;
> @@ -2570,7 +2616,7 @@ static struct nvmf_transport_ops nvme_tcp_transport = {
> NVMF_OPT_HOST_TRADDR | NVMF_OPT_CTRL_LOSS_TMO |
> NVMF_OPT_HDR_DIGEST | NVMF_OPT_DATA_DIGEST |
> NVMF_OPT_NR_WRITE_QUEUES | NVMF_OPT_NR_POLL_QUEUES |
> - NVMF_OPT_TOS,
> + NVMF_OPT_TOS | NVMF_OPT_HOST_IFACE,
> .create_ctrl = nvme_tcp_create_ctrl,
> };
>
> --
> 2.30.2
>
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