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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-24 05:04:00 +08:00
linux-next/samples/bpf/libbpf.c
Daniel Mack d8c5b17f2b samples: bpf: add userspace example for attaching eBPF programs to cgroups
Add a simple userpace program to demonstrate the new API to attach eBPF
programs to cgroups. This is what it does:

 * Create arraymap in kernel with 4 byte keys and 8 byte values

 * Load eBPF program

   The eBPF program accesses the map passed in to store two pieces of
   information. The number of invocations of the program, which maps
   to the number of packets received, is stored to key 0. Key 1 is
   incremented on each iteration by the number of bytes stored in
   the skb.

 * Detach any eBPF program previously attached to the cgroup

 * Attach the new program to the cgroup using BPF_PROG_ATTACH

 * Once a second, read map[0] and map[1] to see how many bytes and
   packets were seen on any socket of tasks in the given cgroup.

The program takes a cgroup path as 1st argument, and either "ingress"
or "egress" as 2nd. Optionally, "drop" can be passed as 3rd argument,
which will make the generated eBPF program return 0 instead of 1, so
the kernel will drop the packet.

libbpf gained two new wrappers for the new syscall commands.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-25 16:26:04 -05:00

177 lines
3.9 KiB
C

/* eBPF mini library */
#include <stdlib.h>
#include <stdio.h>
#include <linux/unistd.h>
#include <unistd.h>
#include <string.h>
#include <linux/netlink.h>
#include <linux/bpf.h>
#include <errno.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <linux/if_packet.h>
#include <arpa/inet.h>
#include "libbpf.h"
static __u64 ptr_to_u64(void *ptr)
{
return (__u64) (unsigned long) ptr;
}
int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size,
int max_entries, int map_flags)
{
union bpf_attr attr = {
.map_type = map_type,
.key_size = key_size,
.value_size = value_size,
.max_entries = max_entries,
.map_flags = map_flags,
};
return syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr));
}
int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags)
{
union bpf_attr attr = {
.map_fd = fd,
.key = ptr_to_u64(key),
.value = ptr_to_u64(value),
.flags = flags,
};
return syscall(__NR_bpf, BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
}
int bpf_lookup_elem(int fd, void *key, void *value)
{
union bpf_attr attr = {
.map_fd = fd,
.key = ptr_to_u64(key),
.value = ptr_to_u64(value),
};
return syscall(__NR_bpf, BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
}
int bpf_delete_elem(int fd, void *key)
{
union bpf_attr attr = {
.map_fd = fd,
.key = ptr_to_u64(key),
};
return syscall(__NR_bpf, BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
}
int bpf_get_next_key(int fd, void *key, void *next_key)
{
union bpf_attr attr = {
.map_fd = fd,
.key = ptr_to_u64(key),
.next_key = ptr_to_u64(next_key),
};
return syscall(__NR_bpf, BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
}
#define ROUND_UP(x, n) (((x) + (n) - 1u) & ~((n) - 1u))
char bpf_log_buf[LOG_BUF_SIZE];
int bpf_prog_load(enum bpf_prog_type prog_type,
const struct bpf_insn *insns, int prog_len,
const char *license, int kern_version)
{
union bpf_attr attr = {
.prog_type = prog_type,
.insns = ptr_to_u64((void *) insns),
.insn_cnt = prog_len / sizeof(struct bpf_insn),
.license = ptr_to_u64((void *) license),
.log_buf = ptr_to_u64(bpf_log_buf),
.log_size = LOG_BUF_SIZE,
.log_level = 1,
};
/* assign one field outside of struct init to make sure any
* padding is zero initialized
*/
attr.kern_version = kern_version;
bpf_log_buf[0] = 0;
return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
}
int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type)
{
union bpf_attr attr = {
.target_fd = target_fd,
.attach_bpf_fd = prog_fd,
.attach_type = type,
};
return syscall(__NR_bpf, BPF_PROG_ATTACH, &attr, sizeof(attr));
}
int bpf_prog_detach(int target_fd, enum bpf_attach_type type)
{
union bpf_attr attr = {
.target_fd = target_fd,
.attach_type = type,
};
return syscall(__NR_bpf, BPF_PROG_DETACH, &attr, sizeof(attr));
}
int bpf_obj_pin(int fd, const char *pathname)
{
union bpf_attr attr = {
.pathname = ptr_to_u64((void *)pathname),
.bpf_fd = fd,
};
return syscall(__NR_bpf, BPF_OBJ_PIN, &attr, sizeof(attr));
}
int bpf_obj_get(const char *pathname)
{
union bpf_attr attr = {
.pathname = ptr_to_u64((void *)pathname),
};
return syscall(__NR_bpf, BPF_OBJ_GET, &attr, sizeof(attr));
}
int open_raw_sock(const char *name)
{
struct sockaddr_ll sll;
int sock;
sock = socket(PF_PACKET, SOCK_RAW | SOCK_NONBLOCK | SOCK_CLOEXEC, htons(ETH_P_ALL));
if (sock < 0) {
printf("cannot create raw socket\n");
return -1;
}
memset(&sll, 0, sizeof(sll));
sll.sll_family = AF_PACKET;
sll.sll_ifindex = if_nametoindex(name);
sll.sll_protocol = htons(ETH_P_ALL);
if (bind(sock, (struct sockaddr *)&sll, sizeof(sll)) < 0) {
printf("bind to %s: %s\n", name, strerror(errno));
close(sock);
return -1;
}
return sock;
}
int perf_event_open(struct perf_event_attr *attr, int pid, int cpu,
int group_fd, unsigned long flags)
{
return syscall(__NR_perf_event_open, attr, pid, cpu,
group_fd, flags);
}