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/* Copyright (C) 2022 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <bpf/bpf.h>
#include <linux/if_link.h>
#include <net/if.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "libknot/endian.h"
#include "libknot/error.h"
#include "libknot/xdp/bpf-kernel-obj.h"
#include "libknot/xdp/bpf-user.h"
#include "libknot/xdp/eth.h"
#include "contrib/openbsd/strlcpy.h"
#define NO_BPF_MAPS 2
static inline bool IS_ERR_OR_NULL(const void *ptr)
{
return (ptr == NULL) || (unsigned long)ptr >= (unsigned long)-4095;
}
static int prog_load(struct bpf_object **pobj, int *prog_fd)
{
struct bpf_program *prog, *first_prog = NULL;
struct bpf_object *obj;
obj = bpf_object__open_mem(bpf_kernel_o, bpf_kernel_o_len, NULL);
if (IS_ERR_OR_NULL(obj)) {
return KNOT_ENOENT;
}
bpf_object__for_each_program(prog, obj) {
bpf_program__set_type(prog, BPF_PROG_TYPE_XDP);
if (first_prog == NULL) {
first_prog = prog;
}
}
if (first_prog == NULL) {
bpf_object__close(obj);
return KNOT_ENOENT;
}
int ret = bpf_object__load(obj);
if (ret != 0) {
bpf_object__close(obj);
return KNOT_EINVAL;
}
*pobj = obj;
*prog_fd = bpf_program__fd(first_prog);
return KNOT_EOK;
}
static int ensure_prog(struct kxsk_iface *iface, bool overwrite)
{
if (bpf_kernel_o_len < 2) {
return KNOT_ENOTSUP;
}
/* Use libbpf for extracting BPF byte-code from BPF-ELF object, and
* loading this into the kernel via bpf-syscall. */
int prog_fd;
int ret = prog_load(&iface->prog_obj, &prog_fd);
if (ret != KNOT_EOK) {
return KNOT_EPROGRAM;
}
#if USE_LIBXDP
ret = bpf_xdp_attach(iface->if_index, prog_fd,
overwrite ? 0 : XDP_FLAGS_UPDATE_IF_NOEXIST, NULL);
#else
ret = bpf_set_link_xdp_fd(iface->if_index, prog_fd,
overwrite ? 0 : XDP_FLAGS_UPDATE_IF_NOEXIST);
#endif
if (ret != 0) {
close(prog_fd);
}
if (ret == -EBUSY && !overwrite) { // We try accepting the present program.
uint32_t prog_id = 0;
#if USE_LIBXDP
ret = bpf_xdp_query_id(iface->if_index, 0, &prog_id);
#else
ret = bpf_get_link_xdp_id(iface->if_index, &prog_id, 0);
#endif
if (ret == 0 && prog_id != 0) {
ret = prog_fd = bpf_prog_get_fd_by_id(prog_id);
}
}
if (ret < 0) {
return KNOT_EFD;
} else {
return prog_fd;
}
}
static void unget_bpf_maps(struct kxsk_iface *iface)
{
if (iface->opts_map_fd >= 0) {
close(iface->opts_map_fd);
}
if (iface->xsks_map_fd >= 0) {
close(iface->xsks_map_fd);
}
iface->opts_map_fd = iface->xsks_map_fd = -1;
}
/*!
* /brief Get FDs for the two maps and assign them into xsk_info-> fields.
*
* Inspired by xsk_lookup_bpf_maps() from libbpf before qidconf_map elimination.
*/
static int get_bpf_maps(int prog_fd, struct kxsk_iface *iface)
{
uint32_t *map_ids = calloc(NO_BPF_MAPS, sizeof(*map_ids));
if (map_ids == NULL) {
return KNOT_ENOMEM;
}
struct bpf_prog_info prog_info = {
.nr_map_ids = NO_BPF_MAPS,
.map_ids = (__u64)(unsigned long)map_ids,
};
uint32_t prog_len = sizeof(struct bpf_prog_info);
int ret = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &prog_len);
if (ret != 0) {
free(map_ids);
return ret;
}
for (int i = 0; i < NO_BPF_MAPS; ++i) {
int fd = bpf_map_get_fd_by_id(map_ids[i]);
if (fd < 0) {
continue;
}
struct bpf_map_info map_info = { 0 };
uint32_t map_len = sizeof(struct bpf_map_info);
ret = bpf_obj_get_info_by_fd(fd, &map_info, &map_len);
if (ret != 0) {
close(fd);
continue;
}
if (strcmp(map_info.name, "opts_map") == 0) {
iface->opts_map_fd = fd;
continue;
}
if (strcmp(map_info.name, "xsks_map") == 0) {
iface->xsks_map_fd = fd;
continue;
}
close(fd);
}
if (iface->opts_map_fd < 0 || iface->xsks_map_fd < 0) {
unget_bpf_maps(iface);
free(map_ids);
return KNOT_ENOENT;
}
free(map_ids);
return KNOT_EOK;
}
int kxsk_socket_start(const struct kxsk_iface *iface, knot_xdp_filter_flag_t flags,
uint16_t udp_port, uint16_t quic_port, struct xsk_socket *xsk)
{
if (iface == NULL || xsk == NULL) {
return KNOT_EINVAL;
}
int fd = xsk_socket__fd(xsk);
int ret = bpf_map_update_elem(iface->xsks_map_fd, &iface->if_queue, &fd, 0);
if (ret != 0) {
return ret;
}
knot_xdp_opts_t opts = {
.flags = flags | KNOT_XDP_FILTER_ON,
.udp_port = udp_port,
.quic_port = quic_port,
};
ret = bpf_map_update_elem(iface->opts_map_fd, &iface->if_queue, &opts, 0);
if (ret != 0) {
(void)bpf_map_delete_elem(iface->xsks_map_fd, &iface->if_queue);
}
return ret;
}
void kxsk_socket_stop(const struct kxsk_iface *iface)
{
if (iface == NULL) {
return;
}
knot_xdp_opts_t opts = { 0 };
(void)bpf_map_update_elem(iface->opts_map_fd, &iface->if_queue, &opts, 0);
(void)bpf_map_delete_elem(iface->xsks_map_fd, &iface->if_queue);
}
int kxsk_iface_new(const char *if_name, unsigned if_queue, knot_xdp_load_bpf_t load_bpf,
struct kxsk_iface **out_iface)
{
if (if_name == NULL || out_iface == NULL) {
return KNOT_EINVAL;
}
struct kxsk_iface *iface = calloc(1, sizeof(*iface) + IFNAMSIZ);
if (iface == NULL) {
return KNOT_ENOMEM;
}
iface->if_name = (char *)(iface + 1);
strlcpy((char *)iface->if_name, if_name, IFNAMSIZ);
iface->if_index = if_nametoindex(if_name);
if (iface->if_index == 0) {
free(iface);
return KNOT_EINVAL;
}
iface->if_queue = if_queue;
iface->opts_map_fd = iface->xsks_map_fd = -1;
int ret;
switch (load_bpf) {
case KNOT_XDP_LOAD_BPF_NEVER:
(void)0;
uint32_t prog_id = 0;
#if USE_LIBXDP
ret = bpf_xdp_query_id(iface->if_index, 0, &prog_id);
#else
ret = bpf_get_link_xdp_id(iface->if_index, &prog_id, 0);
#endif
if (ret == 0) {
if (prog_id == 0) {
ret = KNOT_EPROGRAM;
} else {
ret = bpf_prog_get_fd_by_id(prog_id);
}
}
break;
case KNOT_XDP_LOAD_BPF_ALWAYS_UNLOAD:
#if USE_LIBXDP
(void)bpf_xdp_detach(iface->if_index, 0, NULL);
#else
(void)bpf_set_link_xdp_fd(iface->if_index, -1, 0);
#endif
sleep(1);
// FALLTHROUGH
case KNOT_XDP_LOAD_BPF_ALWAYS:
ret = ensure_prog(iface, true);
break;
case KNOT_XDP_LOAD_BPF_MAYBE:
ret = ensure_prog(iface, false);
break;
default:
return KNOT_EINVAL;
}
if (ret >= 0) {
ret = get_bpf_maps(ret, iface);
}
if (ret < 0) {
free(iface);
return ret;
}
knot_xdp_mode_t mode = knot_eth_xdp_mode(iface->if_index);
if (mode == KNOT_XDP_MODE_NONE) {
free(iface);
return KNOT_ENOTSUP;
}
*out_iface = iface;
return KNOT_EOK;
}
void kxsk_iface_free(struct kxsk_iface *iface)
{
if (iface == NULL) {
return;
}
unget_bpf_maps(iface);
if (iface->prog_obj != NULL) {
bpf_object__close(iface->prog_obj);
}
free(iface);
}
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