[ovs-dev] [PATCHv6] netdev-afxdp: Enable loading XDP program.
William Tu
u9012063 at gmail.com
Thu Jan 16 21:48:15 UTC 2020
Now netdev-afxdp always forwards all packets to userspace because
it is using libbpf's default XDP program, see 'xsk_load_xdp_prog'.
There are some cases when users want to keep packets in kernel instead
of sending to userspace, for example, management traffic such as SSH
should be processed in kernel.
The patch enables loading the user-provided XDP program by
$ovs-vsctl -- set int afxdp-p0 options:xdp-obj=<path/to/xdp/obj>
So users can implement their filtering logic or traffic steering idea
in their XDP program, and rest of the traffic passes to AF_XDP socket
handled by OVS.
Signed-off-by: William Tu <u9012063 at gmail.com>
---
v6:
- rebase to master
- mostly remains the same as v5, but make sure there is no
leak using bpftool and no repeated loop issued reported from Eelco
here:
https://patchwork.ozlabs.org/patch/1199734/
which has been fixed at
netdev-afxdp: Avoid removing of XDP program if not loaded.
- travis: https://travis-ci.org/williamtu/ovs-travis/builds/638126505
v5:
- rebase to master
Feedbacks from Eelco:
- Remove xdp-obj="__default__" case, to remove xdp-obj, use
ovs-vsctl remove int <dev> options xdp-obj
- Fix problem of xdp program not unloading
verify by bpftool.
- use xdp-obj instead of xdpobj
- Limitation: xdp-obj doesn't work when using best-effort-mode
because best-effort mode tried to probe mode by setting up queue,
and loading xdp-obj requires knwoing mode in advance.
(to support it, we might need to use the
XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD as in v3)
Testing
- I place two xdp binary here
https://drive.google.com/open?id=1QCCdNE-5CwlKCFV6Upg9mOPnnbVkUwA5
[xdpsock_pass.o] Working one, which forwards packets to dpif-netdev
[xdpsock_invalid.o] invalid one, which has no map
v4:
Feedbacks from Eelco.
- First load the program, then configure xsk.
Let API take care of xdp prog and map loading, don't set
XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD.
- When loading custom xdp, need to close(prog_fd) and close(map_fd)
to release the resources
- make sure prog and map is unloaded by bpftool.
- update doc, afxdp.rst
- Tested-at: https://travis-ci.org/williamtu/ovs-travis/builds/608986781
v3:
Feedbacks from Eelco.
- keep using xdpobj not xdp-obj (because we alread use xdpmode)
or we change both to xdp-obj and xdp-mode?
- log a info message when using external program for better debugging
- combine some failure messages
- update doc
NEW:
- add options:xdpobj=__default__, to set back to libbpf default prog
- Tested-at: https://travis-ci.org/williamtu/ovs-travis/builds/606153231
v2:
A couple fixes and remove RFC
---
Documentation/intro/install/afxdp.rst | 59 +++++++++++++++
NEWS | 2 +
lib/netdev-afxdp.c | 135 ++++++++++++++++++++++++++++++++--
lib/netdev-linux-private.h | 4 +
4 files changed, 193 insertions(+), 7 deletions(-)
diff --git a/Documentation/intro/install/afxdp.rst b/Documentation/intro/install/afxdp.rst
index 15e3c918f942..e72bb3edabe6 100644
--- a/Documentation/intro/install/afxdp.rst
+++ b/Documentation/intro/install/afxdp.rst
@@ -283,6 +283,65 @@ Or, use OVS pmd tool::
ovs-appctl dpif-netdev/pmd-stats-show
+Loading Custom XDP Program
+--------------------------
+By defailt, netdev-afxdp always forwards all packets to userspace because
+it is using libbpf's default XDP program. There are some cases when users
+want to keep packets in kernel instead of sending to userspace, for example,
+management traffic such as SSH should be processed in kernel. This can be
+done by loading the user-provided XDP program::
+
+ ovs-vsctl -- set int afxdp-p0 options:xdp-obj=<path/to/xdp/obj>
+
+So users can implement their filtering logic or traffic steering idea
+in their XDP program, and rest of the traffic passes to AF_XDP socket
+handled by OVS. To set it back to default, use::
+
+ ovs-vsctl remove int afxdp-p0 options xdp-obj
+
+Below is a sample C program compiled under kernel's samples/bpf/.
+
+.. code-block:: c
+
+ #include <uapi/linux/bpf.h>
+ #include "bpf_helpers.h"
+
+ #if LINUX_VERSION_CODE < KERNEL_VERSION(5,3,0)
+ /* Kernel version before 5.3 needed an additional map */
+ struct bpf_map_def SEC("maps") qidconf_map = {
+ .type = BPF_MAP_TYPE_ARRAY,
+ .key_size = sizeof(int),
+ .value_size = sizeof(int),
+ .max_entries = 64,
+ };
+ #endif
+
+ /* OVS will associate map 'xsks_map' to xsk socket. */
+ struct bpf_map_def SEC("maps") xsks_map = {
+ .type = BPF_MAP_TYPE_XSKMAP,
+ .key_size = sizeof(int),
+ .value_size = sizeof(int),
+ .max_entries = 32,
+ };
+
+ SEC("xdp_sock")
+ int xdp_sock_prog(struct xdp_md *ctx)
+ {
+ int index = ctx->rx_queue_index;
+
+ /* Customized by user.
+ * For example
+ * 1) filter out all SSH traffic and return XDP_PASS
+ * for kernel to process.
+ * 2) Drop unwanted packet by returning XDP_DROP.
+ */
+
+ /* Rest of packets goes to AF_XDP. */
+ return bpf_redirect_map(&xsks_map, index, 0);
+ }
+ char _license[] SEC("license") = "GPL";
+
+
Example Script
--------------
diff --git a/NEWS b/NEWS
index e8d662a0c15f..a939262ce09e 100644
--- a/NEWS
+++ b/NEWS
@@ -19,6 +19,8 @@ Post-v2.12.0
generic - former SKB
best-effort [default] - new one, chooses the best available from
3 above modes
+ * New option 'xdp-obj' for loading custom XDP program. Default uses
+ the libbpf builtin XDP program.
- DPDK:
* DPDK pdump packet capture support disabled by default. New configure
option '--enable-dpdk-pdump' to enable it.
diff --git a/lib/netdev-afxdp.c b/lib/netdev-afxdp.c
index 6ac0bc2dde90..421566e36a40 100644
--- a/lib/netdev-afxdp.c
+++ b/lib/netdev-afxdp.c
@@ -21,6 +21,7 @@
#include "netdev-afxdp.h"
#include "netdev-afxdp-pool.h"
+#include <bpf/bpf.h>
#include <errno.h>
#include <inttypes.h>
#include <linux/rtnetlink.h>
@@ -30,6 +31,7 @@
#include <stdlib.h>
#include <sys/resource.h>
#include <sys/socket.h>
+#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
@@ -93,7 +95,8 @@ static struct xsk_socket_info *xsk_configure(int ifindex, int xdp_queue_id,
enum afxdp_mode mode,
bool use_need_wakeup,
bool report_socket_failures);
-static void xsk_remove_xdp_program(uint32_t ifindex, enum afxdp_mode);
+static void xsk_remove_xdp_program(uint32_t ifindex, enum afxdp_mode,
+ int prog_fd, int map_fd);
static void xsk_destroy(struct xsk_socket_info *xsk);
static int xsk_configure_all(struct netdev *netdev);
static void xsk_destroy_all(struct netdev *netdev);
@@ -255,6 +258,23 @@ netdev_afxdp_sweep_unused_pools(void *aux OVS_UNUSED)
ovs_mutex_unlock(&unused_pools_mutex);
}
+static int
+xsk_load_prog(const char *path, struct bpf_object **obj,
+ int *prog_fd)
+{
+ struct bpf_prog_load_attr attr = {
+ .prog_type = BPF_PROG_TYPE_XDP,
+ .file = path,
+ };
+
+ if (bpf_prog_load_xattr(&attr, obj, prog_fd)) {
+ VLOG_ERR("Can't load XDP program at '%s'", path);
+ return EINVAL;
+ }
+
+ return 0;
+}
+
static struct xsk_umem_info *
xsk_configure_umem(void *buffer, uint64_t size)
{
@@ -471,6 +491,50 @@ xsk_configure_queue(struct netdev_linux *dev, int ifindex, int queue_id,
return 0;
}
+static int
+xsk_configure_prog(struct netdev *netdev, int ifindex)
+{
+ struct netdev_linux *dev = netdev_linux_cast(netdev);
+ struct bpf_object *obj;
+ uint32_t prog_id = 0;
+ uint32_t flags;
+ int prog_fd = 0;
+ int map_fd = 0;
+ int mode;
+ int ret;
+
+ mode = dev->xdp_mode_in_use;
+ flags = xdp_modes[mode].xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST;
+
+ ret = xsk_load_prog(dev->xdp_obj, &obj, &prog_fd);
+ if (ret) {
+ goto err;
+ }
+ dev->prog_fd = prog_fd;
+
+ bpf_set_link_xdp_fd(ifindex, prog_fd, flags);
+ ret = bpf_get_link_xdp_id(ifindex, &prog_id, flags);
+ if (ret < 0) {
+ VLOG_ERR("%s: Cannot get XDP prog id.",
+ netdev_get_name(netdev));
+ goto err;
+ }
+
+ map_fd = bpf_object__find_map_fd_by_name(obj, "xsks_map");
+ if (map_fd < 0) {
+ VLOG_ERR("%s: Cannot find \"xsks_map\".",
+ netdev_get_name(netdev));
+ goto err;
+ }
+ dev->map_fd = map_fd;
+
+ VLOG_INFO("%s: Loaded custom XDP program at %s prog_id %d.",
+ netdev_get_name(netdev), dev->xdp_obj, prog_id);
+ return 0;
+
+err:
+ return ret;
+}
static int
xsk_configure_all(struct netdev *netdev)
@@ -507,6 +571,13 @@ xsk_configure_all(struct netdev *netdev)
qid++;
} else {
dev->xdp_mode_in_use = dev->xdp_mode;
+ if (dev->xdp_obj) {
+ /* XDP program is per-netdev, so all queues share
+ * the same XDP program. */
+ if (xsk_configure_prog(netdev, ifindex)) {
+ goto err;
+ }
+ }
}
/* Configure remaining queues. */
@@ -581,7 +652,12 @@ xsk_destroy_all(struct netdev *netdev)
VLOG_INFO("%s: Removing xdp program.", netdev_get_name(netdev));
ifindex = linux_get_ifindex(netdev_get_name(netdev));
- xsk_remove_xdp_program(ifindex, dev->xdp_mode_in_use);
+ xsk_remove_xdp_program(ifindex, dev->xdp_mode_in_use, dev->prog_fd,
+ dev->map_fd);
+ dev->prog_fd = 0;
+ dev->map_fd = 0;
+ free(CONST_CAST(char *, dev->xdp_obj));
+ dev->xdp_obj = NULL;
if (dev->tx_locks) {
for (i = 0; i < netdev_n_txq(netdev); i++) {
@@ -598,9 +674,11 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args,
{
struct netdev_linux *dev = netdev_linux_cast(netdev);
const char *str_xdp_mode;
+ const char *str_xdp_obj;
enum afxdp_mode xdp_mode;
bool need_wakeup;
int new_n_rxq;
+ struct stat s;
ovs_mutex_lock(&dev->mutex);
new_n_rxq = MAX(smap_get_int(args, "n_rxq", NR_QUEUE), 1);
@@ -634,12 +712,34 @@ netdev_afxdp_set_config(struct netdev *netdev, const struct smap *args,
}
#endif
+ str_xdp_obj = smap_get_def(args, "xdp-obj", NULL);
+ if (str_xdp_obj) {
+ if (stat(str_xdp_obj, &s)) {
+ ovs_mutex_unlock(&dev->mutex);
+ VLOG_ERR("Invalid xdp-obj '%s': %s.", str_xdp_obj,
+ ovs_strerror(errno));
+ return EINVAL;
+ } else if (!S_ISREG(s.st_mode)) {
+ ovs_mutex_unlock(&dev->mutex);
+ VLOG_ERR("xdp-obj '%s' is not a regular file.", str_xdp_obj);
+ return EINVAL;
+ }
+ }
+
+ if (str_xdp_obj && xdp_mode == OVS_AF_XDP_MODE_BEST_EFFORT) {
+ ovs_mutex_unlock(&dev->mutex);
+ VLOG_ERR("best-effort mode and xdp-obj can't be set together");
+ return EINVAL;
+ }
+
if (dev->requested_n_rxq != new_n_rxq
|| dev->requested_xdp_mode != xdp_mode
- || dev->requested_need_wakeup != need_wakeup) {
+ || dev->requested_need_wakeup != need_wakeup
+ || !nullable_string_is_equal(dev->requested_xdp_obj, str_xdp_obj)) {
dev->requested_n_rxq = new_n_rxq;
dev->requested_xdp_mode = xdp_mode;
dev->requested_need_wakeup = need_wakeup;
+ dev->requested_xdp_obj = nullable_xstrdup(str_xdp_obj);
netdev_request_reconfigure(netdev);
}
ovs_mutex_unlock(&dev->mutex);
@@ -658,6 +758,8 @@ netdev_afxdp_get_config(const struct netdev *netdev, struct smap *args)
xdp_modes[dev->xdp_mode_in_use].name);
smap_add_format(args, "use-need-wakeup", "%s",
dev->use_need_wakeup ? "true" : "false");
+ smap_add_format(args, "xdp-obj", "%s",
+ dev->xdp_obj ? dev->xdp_obj : "builtin");
ovs_mutex_unlock(&dev->mutex);
return 0;
}
@@ -674,7 +776,8 @@ netdev_afxdp_reconfigure(struct netdev *netdev)
if (netdev->n_rxq == dev->requested_n_rxq
&& dev->xdp_mode == dev->requested_xdp_mode
&& dev->use_need_wakeup == dev->requested_need_wakeup
- && dev->xsks) {
+ && dev->xsks
+ && nullable_string_is_equal(dev->xdp_obj, dev->requested_xdp_obj)) {
goto out;
}
@@ -692,6 +795,8 @@ netdev_afxdp_reconfigure(struct netdev *netdev)
}
dev->use_need_wakeup = dev->requested_need_wakeup;
+ dev->xdp_obj = dev->requested_xdp_obj;
+
err = xsk_configure_all(netdev);
if (err) {
VLOG_ERR("%s: AF_XDP device reconfiguration failed.",
@@ -715,7 +820,8 @@ netdev_afxdp_get_numa_id(const struct netdev *netdev)
}
static void
-xsk_remove_xdp_program(uint32_t ifindex, enum afxdp_mode mode)
+xsk_remove_xdp_program(uint32_t ifindex, enum afxdp_mode mode,
+ int prog_fd, int map_fd)
{
uint32_t flags = xdp_modes[mode].xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST;
uint32_t ret, prog_id = 0;
@@ -732,7 +838,19 @@ xsk_remove_xdp_program(uint32_t ifindex, enum afxdp_mode mode)
return;
}
- bpf_set_link_xdp_fd(ifindex, -1, flags);
+ ret = bpf_set_link_xdp_fd(ifindex, -1, flags);
+ if (ret) {
+ VLOG_ERR("Failed to unload prog ID: %d", prog_id);
+ }
+
+ if (prog_fd) {
+ close(prog_fd);
+ }
+ if (map_fd) {
+ close(map_fd);
+ }
+
+ VLOG_INFO("Removed XDP program ID: %d", prog_id);
}
void
@@ -744,7 +862,8 @@ signal_remove_xdp(struct netdev *netdev)
ifindex = linux_get_ifindex(netdev_get_name(netdev));
VLOG_WARN("Force removing xdp program.");
- xsk_remove_xdp_program(ifindex, dev->xdp_mode_in_use);
+ xsk_remove_xdp_program(ifindex, dev->xdp_mode_in_use,
+ dev->prog_fd, dev->map_fd);
}
static struct dp_packet_afxdp *
@@ -1158,10 +1277,12 @@ netdev_afxdp_construct(struct netdev *netdev)
netdev->n_txq = 0;
dev->xdp_mode = OVS_AF_XDP_MODE_UNSPEC;
dev->xdp_mode_in_use = OVS_AF_XDP_MODE_UNSPEC;
+ dev->xdp_obj = NULL;
dev->requested_n_rxq = NR_QUEUE;
dev->requested_xdp_mode = OVS_AF_XDP_MODE_BEST_EFFORT;
dev->requested_need_wakeup = NEED_WAKEUP_DEFAULT;
+ dev->requested_xdp_obj = NULL;
dev->xsks = NULL;
dev->tx_locks = NULL;
diff --git a/lib/netdev-linux-private.h b/lib/netdev-linux-private.h
index f08159aa7b53..190927cec098 100644
--- a/lib/netdev-linux-private.h
+++ b/lib/netdev-linux-private.h
@@ -109,6 +109,10 @@ struct netdev_linux {
bool requested_need_wakeup;
struct netdev_afxdp_tx_lock *tx_locks; /* Array of locks for TX queues. */
+ const char *xdp_obj; /* XDP object file path. */
+ const char *requested_xdp_obj;
+ int prog_fd;
+ int map_fd;
#endif
};
--
2.7.4
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