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591 lines (495 loc) · 16.4 KB
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/*
* Copyright (c) 2015 PLUMgrid, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <linux/bpf.h>
#include <linux/if_packet.h>
#include <linux/pkt_cls.h>
#include <linux/perf_event.h>
#include <linux/rtnetlink.h>
#include <linux/unistd.h>
#include <linux/version.h>
#include <linux/bpf_common.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/resource.h>
#include <unistd.h>
#include <stdbool.h>
#include "libbpf.h"
#include "perf_reader.h"
// TODO: remove these defines when linux-libc-dev exports them properly
#ifndef __NR_bpf
#if defined(__powerpc64__)
#define __NR_bpf 361
#else
#define __NR_bpf 321
#endif
#endif
#ifndef SO_ATTACH_BPF
#define SO_ATTACH_BPF 50
#endif
#ifndef PERF_EVENT_IOC_SET_BPF
#define PERF_EVENT_IOC_SET_BPF _IOW('$', 8, __u32)
#endif
#ifndef PERF_FLAG_FD_CLOEXEC
#define PERF_FLAG_FD_CLOEXEC (1UL << 3)
#endif
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)
{
union bpf_attr attr;
memset(&attr, 0, sizeof(attr));
attr.map_type = map_type;
attr.key_size = key_size;
attr.value_size = value_size;
attr.max_entries = max_entries;
int ret = syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr));
if (ret < 0 && errno == EPERM) {
// see note below about the rationale for this retry
struct rlimit rl = {};
if (getrlimit(RLIMIT_MEMLOCK, &rl) == 0) {
rl.rlim_max = RLIM_INFINITY;
rl.rlim_cur = rl.rlim_max;
if (setrlimit(RLIMIT_MEMLOCK, &rl) == 0)
ret = syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr));
}
}
return ret;
}
int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags)
{
union bpf_attr attr;
memset(&attr, 0, sizeof(attr));
attr.map_fd = fd;
attr.key = ptr_to_u64(key);
attr.value = ptr_to_u64(value);
attr.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;
memset(&attr, 0, sizeof(attr));
attr.map_fd = fd;
attr.key = ptr_to_u64(key);
attr.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;
memset(&attr, 0, sizeof(attr));
attr.map_fd = fd;
attr.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;
memset(&attr, 0, sizeof(attr));
attr.map_fd = fd;
attr.key = ptr_to_u64(key);
attr.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))
int bpf_prog_load(enum bpf_prog_type prog_type,
const struct bpf_insn *insns, int prog_len,
const char *license, unsigned kern_version,
char *log_buf, unsigned log_buf_size)
{
union bpf_attr attr;
char *bpf_log_buffer = NULL;
unsigned buffer_size = 0;
int ret = 0;
memset(&attr, 0, sizeof(attr));
attr.prog_type = prog_type;
attr.insns = ptr_to_u64((void *) insns);
attr.insn_cnt = prog_len / sizeof(struct bpf_insn);
attr.license = ptr_to_u64((void *) license);
attr.log_buf = ptr_to_u64(log_buf);
attr.log_size = log_buf_size;
attr.log_level = log_buf ? 1 : 0;
attr.kern_version = kern_version;
if (log_buf)
log_buf[0] = 0;
if (attr.insn_cnt > BPF_MAXINSNS) {
ret = -1;
errno = EINVAL;
fprintf(stderr,
"bpf: %s. Program too large (%d insns), at most %d insns\n\n",
strerror(errno), attr.insn_cnt, BPF_MAXINSNS);
return ret;
}
ret = syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
if (ret < 0 && errno == EPERM) {
// When EPERM is returned, two reasons are possible:
// 1. user has no permissions for bpf()
// 2. user has insufficent rlimit for locked memory
// Unfortunately, there is no api to inspect the current usage of locked
// mem for the user, so an accurate calculation of how much memory to lock
// for this new program is difficult to calculate. As a hack, bump the limit
// to unlimited. If program load fails again, return the error.
struct rlimit rl = {};
if (getrlimit(RLIMIT_MEMLOCK, &rl) == 0) {
rl.rlim_max = RLIM_INFINITY;
rl.rlim_cur = rl.rlim_max;
if (setrlimit(RLIMIT_MEMLOCK, &rl) == 0)
ret = syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
}
}
if (ret < 0 && !log_buf) {
buffer_size = LOG_BUF_SIZE;
// caller did not specify log_buf but failure should be printed,
// so repeat the syscall and print the result to stderr
for (;;) {
bpf_log_buffer = malloc(buffer_size);
if (!bpf_log_buffer) {
fprintf(stderr,
"bpf: buffer log memory allocation failed for error %s\n\n",
strerror(errno));
return ret;
}
attr.log_buf = ptr_to_u64(bpf_log_buffer);
attr.log_size = buffer_size;
attr.log_level = bpf_log_buffer ? 1 : 0;
ret = syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
if (ret < 0 && errno == ENOSPC) {
free(bpf_log_buffer);
bpf_log_buffer = NULL;
buffer_size <<= 1;
} else {
break;
}
}
fprintf(stderr, "bpf: %s\n%s\n", strerror(errno), bpf_log_buffer);
free(bpf_log_buffer);
}
return ret;
}
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 bpf_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 bpf_attach_socket(int sock, int prog) {
return setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog, sizeof(prog));
}
static int bpf_attach_tracing_event(int progfd, const char *event_path,
struct perf_reader *reader, int pid, int cpu, int group_fd) {
int efd, pfd;
ssize_t bytes;
char buf[256];
struct perf_event_attr attr = {};
snprintf(buf, sizeof(buf), "%s/id", event_path);
efd = open(buf, O_RDONLY, 0);
if (efd < 0) {
fprintf(stderr, "open(%s): %s\n", buf, strerror(errno));
return -1;
}
bytes = read(efd, buf, sizeof(buf));
if (bytes <= 0 || bytes >= sizeof(buf)) {
fprintf(stderr, "read(%s): %s\n", buf, strerror(errno));
close(efd);
return -1;
}
close(efd);
buf[bytes] = '\0';
attr.config = strtol(buf, NULL, 0);
attr.type = PERF_TYPE_TRACEPOINT;
attr.sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CALLCHAIN;
attr.sample_period = 1;
attr.wakeup_events = 1;
pfd = syscall(__NR_perf_event_open, &attr, pid, cpu, group_fd, PERF_FLAG_FD_CLOEXEC);
if (pfd < 0) {
fprintf(stderr, "perf_event_open(%s/id): %s\n", event_path, strerror(errno));
return -1;
}
perf_reader_set_fd(reader, pfd);
if (perf_reader_mmap(reader, attr.type, attr.sample_type) < 0)
return -1;
if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, progfd) < 0) {
perror("ioctl(PERF_EVENT_IOC_SET_BPF)");
return -1;
}
if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
perror("ioctl(PERF_EVENT_IOC_ENABLE)");
return -1;
}
return 0;
}
static void * bpf_attach_probe(int progfd, const char *event,
const char *event_desc, const char *event_type,
pid_t pid, int cpu, int group_fd,
perf_reader_cb cb, void *cb_cookie) {
int kfd;
char buf[256];
struct perf_reader *reader = NULL;
reader = perf_reader_new(cb, NULL, cb_cookie);
if (!reader)
goto error;
snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events", event_type);
kfd = open(buf, O_WRONLY | O_APPEND, 0);
if (kfd < 0) {
fprintf(stderr, "open(%s): %s\n", buf, strerror(errno));
goto error;
}
if (write(kfd, event_desc, strlen(event_desc)) < 0) {
fprintf(stderr, "write(%s, \"%s\") failed: %s\n", buf, event_desc, strerror(errno));
if (errno == EINVAL)
fprintf(stderr, "check dmesg output for possible cause\n");
close(kfd);
goto error;
}
close(kfd);
snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s", event_type, event);
if (bpf_attach_tracing_event(progfd, buf, reader, pid, cpu, group_fd) < 0)
goto error;
return reader;
error:
perf_reader_free(reader);
return NULL;
}
void * bpf_attach_kprobe(int progfd, const char *event,
const char *event_desc,
pid_t pid, int cpu, int group_fd,
perf_reader_cb cb, void *cb_cookie) {
return bpf_attach_probe(progfd, event, event_desc, "kprobe", pid, cpu, group_fd, cb, cb_cookie);
}
void * bpf_attach_uprobe(int progfd, const char *event,
const char *event_desc,
pid_t pid, int cpu, int group_fd,
perf_reader_cb cb, void *cb_cookie) {
return bpf_attach_probe(progfd, event, event_desc, "uprobe", pid, cpu, group_fd, cb, cb_cookie);
}
static int bpf_detach_probe(const char *event_desc, const char *event_type) {
int kfd;
char buf[256];
snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events", event_type);
kfd = open(buf, O_WRONLY | O_APPEND, 0);
if (kfd < 0) {
fprintf(stderr, "open(%s): %s\n", buf, strerror(errno));
return -1;
}
if (write(kfd, event_desc, strlen(event_desc)) < 0) {
fprintf(stderr, "write(%s): %s\n", buf, strerror(errno));
close(kfd);
return -1;
}
close(kfd);
return 0;
}
int bpf_detach_kprobe(const char *event_desc) {
return bpf_detach_probe(event_desc, "kprobe");
}
int bpf_detach_uprobe(const char *event_desc) {
return bpf_detach_probe(event_desc, "uprobe");
}
void * bpf_attach_tracepoint(int progfd, const char *tp_category,
const char *tp_name, int pid, int cpu,
int group_fd, perf_reader_cb cb, void *cb_cookie) {
char buf[256];
struct perf_reader *reader = NULL;
reader = perf_reader_new(cb, NULL, cb_cookie);
if (!reader)
goto error;
snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%s/%s",
tp_category, tp_name);
if (bpf_attach_tracing_event(progfd, buf, reader, pid, cpu, group_fd) < 0)
goto error;
return reader;
error:
perf_reader_free(reader);
return NULL;
}
int bpf_detach_tracepoint(const char *tp_category, const char *tp_name) {
// Right now, there is nothing to do, but it's a good idea to encourage
// callers to detach anything they attach.
return 0;
}
void * bpf_open_perf_buffer(perf_reader_raw_cb raw_cb, void *cb_cookie, int pid, int cpu) {
int pfd;
struct perf_event_attr attr = {};
struct perf_reader *reader = NULL;
reader = perf_reader_new(NULL, raw_cb, cb_cookie);
if (!reader)
goto error;
attr.config = 10;//PERF_COUNT_SW_BPF_OUTPUT;
attr.type = PERF_TYPE_SOFTWARE;
attr.sample_type = PERF_SAMPLE_RAW;
attr.sample_period = 1;
attr.wakeup_events = 1;
pfd = syscall(__NR_perf_event_open, &attr, pid, cpu, -1, PERF_FLAG_FD_CLOEXEC);
if (pfd < 0) {
fprintf(stderr, "perf_event_open: %s\n", strerror(errno));
fprintf(stderr, " (check your kernel for PERF_COUNT_SW_BPF_OUTPUT support, 4.4 or newer)\n");
goto error;
}
perf_reader_set_fd(reader, pfd);
if (perf_reader_mmap(reader, attr.type, attr.sample_type) < 0)
goto error;
if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
perror("ioctl(PERF_EVENT_IOC_ENABLE)");
goto error;
}
return reader;
error:
if (reader)
perf_reader_free(reader);
return NULL;
}
int bpf_open_perf_event(uint32_t type, uint64_t config, int pid, int cpu) {
int fd;
struct perf_event_attr attr = {};
attr.sample_period = LONG_MAX;
attr.type = type;
attr.config = config;
fd = syscall(__NR_perf_event_open, &attr, pid, cpu, -1, PERF_FLAG_FD_CLOEXEC);
if (fd < 0) {
fprintf(stderr, "perf_event_open: %s\n", strerror(errno));
return -1;
}
if (ioctl(fd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
perror("ioctl(PERF_EVENT_IOC_ENABLE)");
close(fd);
return -1;
}
return fd;
}
int bpf_attach_xdp(const char *dev_name, int progfd) {
struct sockaddr_nl sa;
int sock, seq = 0, len, ret = -1;
char buf[4096];
struct nlattr *nla, *nla_xdp;
struct {
struct nlmsghdr nh;
struct ifinfomsg ifinfo;
char attrbuf[64];
} req;
struct nlmsghdr *nh;
struct nlmsgerr *err;
memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK;
sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (sock < 0) {
fprintf(stderr, "bpf: opening a netlink socket: %s\n", strerror(errno));
return -1;
}
if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
fprintf(stderr, "bpf: bind to netlink: %s\n", strerror(errno));
goto cleanup;
}
memset(&req, 0, sizeof(req));
req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
req.nh.nlmsg_type = RTM_SETLINK;
req.nh.nlmsg_pid = 0;
req.nh.nlmsg_seq = ++seq;
req.ifinfo.ifi_family = AF_UNSPEC;
req.ifinfo.ifi_index = if_nametoindex(dev_name);
if (req.ifinfo.ifi_index == 0) {
fprintf(stderr, "bpf: Resolving device name to index: %s\n", strerror(errno));
goto cleanup;
}
nla = (struct nlattr *)(((char *)&req)
+ NLMSG_ALIGN(req.nh.nlmsg_len));
nla->nla_type = NLA_F_NESTED | 43/*IFLA_XDP*/;
nla_xdp = (struct nlattr *)((char *)nla + NLA_HDRLEN);
// we specify the FD passed over by the user
nla_xdp->nla_type = 1/*IFLA_XDP_FD*/;
nla_xdp->nla_len = NLA_HDRLEN + sizeof(int);
memcpy((char *)nla_xdp + NLA_HDRLEN, &progfd, sizeof(progfd));
nla->nla_len = NLA_HDRLEN + nla_xdp->nla_len;
req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);
if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) {
fprintf(stderr, "bpf: send to netlink: %s\n", strerror(errno));
goto cleanup;
}
len = recv(sock, buf, sizeof(buf), 0);
if (len < 0) {
fprintf(stderr, "bpf: recv from netlink: %s\n", strerror(errno));
goto cleanup;
}
for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
nh = NLMSG_NEXT(nh, len)) {
if (nh->nlmsg_pid != getpid()) {
fprintf(stderr, "bpf: Wrong pid %d, expected %d\n",
nh->nlmsg_pid, getpid());
errno = EBADMSG;
goto cleanup;
}
if (nh->nlmsg_seq != seq) {
fprintf(stderr, "bpf: Wrong seq %d, expected %d\n",
nh->nlmsg_seq, seq);
errno = EBADMSG;
goto cleanup;
}
switch (nh->nlmsg_type) {
case NLMSG_ERROR:
err = (struct nlmsgerr *)NLMSG_DATA(nh);
if (!err->error)
continue;
fprintf(stderr, "bpf: nlmsg error %s\n", strerror(-err->error));
errno = -err->error;
goto cleanup;
case NLMSG_DONE:
break;
}
}
ret = 0;
cleanup:
close(sock);
return ret;
}