所以我有一個內核 ebpf 程式，它將 xdp 鉤子附加到介面 eno1，在其中我有一個ip_mapBPF_MAP_TYPE_HASH 型別的映射，我正在與用戶空間共享。因此，在我的用戶空間中，我正在獲取地圖的檔案描述符，但是現在我想
struct share_me在我的用戶空間加載程式中借助 BPF_MAP_TYPE_HASH 型別地圖來獲取我正在共享的更新值。
任何人都請幫我解釋一下，至于我該怎么做，
所以我假設如果我map_fd指向 BPF_MAP_TYPE_HASH 指向我的 MAP，那么我可以這樣做，這樣我就可以 從內核 ebpf 程式int sizeof_share_me_read=read(map_fd,&share_me,sizeof(struct share_me));中讀取我的共享的當前更新值，并且它將在share_me 物件的成員中包含當前資料包的 ip 標頭. 誰能幫我解決這個問題map_fd(BPF_MAP_TYPE_HASH)struct iphdr dest_ip
用戶.c
/* SPDX-License-Identifier: GPL-2.0 */
#include <assert.h>
#include <errno.h>
#include <getopt.h>
#include <locale.h>
#include <poll.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/resource.h>
#include <bpf/bpf.h>
#include <bpf/xsk.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <linux/if_link.h>
#include <linux/if_ether.h>
#include <linux/ipv6.h>
#include <linux/icmpv6.h>
#include "../common/common_params.h"
#include "../common/common_user_bpf_xdp.h"
#include "../common/common_libbpf.h"
int main()
{
struct bpf_object *bpf_obj;
struct bpf_program *bpf_prog;
bpf_obj = load_bpf_object_file("af_xdp_kern.o", 0);
if (!bpf_obj) {
printf("ERR: loading file:\n");
exit(EXIT_FAIL_BPF);
}
bpf_prog = bpf_program__next(NULL, bpf_obj);
if (!bpf_prog)
{
printf("bpf_program_next:\n");
exit(0);
}
int prog_fd = bpf_program__fd(bpf_prog);
if (prog_fd <= 0) {
}
int err = xdp_link_attach(if_nametoindex("eno1"), 0, prog_fd);
if(err)
{
printf("xdp_link_attach\n");
exit(0);
}
struct bpf_map *map1 = bpf_object__find_map_by_name(bpf_obj, "ip_map");
int map_fd = bpf_map__fd(map1);
if(map_fd<0)
{
printf("map fd <0\n");
exit(0);
}
return 0;
}
內核.c
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <linux/if_ether.h>
#include <linux/ip.h>
#include <linux/udp.h>
void *memcpy(void *, const void *, unsigned long);
int IPPROTO_UDP = 17;
struct share_me
{
struct iphdr dest_ip;
};
struct bpf_map_def SEC("maps") ip_map = {
.type = BPF_MAP_TYPE_HASH,
.key_size = sizeof(int),
.value_size = sizeof(struct share_me),
.max_entries = 64, /* Assume netdev has no more than 64 queues */
};
struct bpf_map_def SEC("maps") xsks_map = {
.type = BPF_MAP_TYPE_XSKMAP,
.key_size = sizeof(int),
.value_size = sizeof(int),
.max_entries = 64, /* Assume netdev has no more than 64 queues */
};
struct bpf_map_def SEC("maps") xdp_stats_map = {
.type = BPF_MAP_TYPE_PERCPU_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(__u32),
.max_entries = 64,
};
SEC("xdp_sock")
int xdp_sock_prog(struct xdp_md *ctx)
{
int index = ctx->rx_queue_index;
__u32 *pkt_count;
void *data = (void *)(long)ctx->data;
void *data_end = (void *)(long)ctx->data_end;
struct ethhdr *eth = data;
struct share_me me;
if ((void *)eth sizeof(*eth) <= data_end)
{
struct iphdr *ip = data sizeof(*eth);
//me.dest_ip=ip;
if(((void *)ip sizeof(*ip))<=data_end)
{
struct iphdr ip_temp=(struct iphdr)*ip;
memcpy(&me.dest_ip,&ip_temp,sizeof(ip_temp));
bpf_map_lookup_elem(&ip_map, &index);
bpf_map_update_elem(&ip_map,&index,&me,0);
if ((void *)ip sizeof(*ip) <= data_end)
{
if (ip->protocol == IPPROTO_UDP)
{
struct udphdr *udp = (void *)ip sizeof(*ip);
if ((void *)udp sizeof(*udp) <= data_end)
{
//u64 value = htons(udp->dest);
//counter.increment(value);
}
}
}
}
}
pkt_count = bpf_map_lookup_elem(&xdp_stats_map, &index);
if (pkt_count) {
/* We pass every other packet */
if ((*pkt_count) & 1)
return XDP_DROP;
}
/* A set entry here means that the correspnding queue_id
* has an active AF_XDP socket bound to it. */
if (bpf_map_lookup_elem(&xsks_map, &index))
return bpf_redirect_map(&xsks_map, index, 0);
return XDP_PASS;
}
char _license[] SEC("license") = "GPL";
uj5u.com熱心網友回復：
現在您有了 map fd，您需要使用libbpf 的 bpf_map_lookup_elem函式來讀取值：
int key = 0;
struct share_me value = {};
if (bpf_map_lookup_elem(map_fd, &key, &value))
// Print errno.
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