18ef5dac93
Open code obj_get_info_by_fd in bpf preload. It's the last part of libbpf that preload/iterators were using. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20220131220528.98088-7-alexei.starovoitov@gmail.com
109 lines
2.6 KiB
C
109 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2020 Facebook */
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/resource.h>
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#include <bpf/libbpf.h>
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#include <bpf/bpf.h>
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#include <sys/mount.h>
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#include "iterators.lskel.h"
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#include "bpf_preload_common.h"
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int to_kernel = -1;
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int from_kernel = 0;
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static int __bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len)
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{
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union bpf_attr attr;
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int err;
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memset(&attr, 0, sizeof(attr));
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attr.info.bpf_fd = bpf_fd;
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attr.info.info_len = *info_len;
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attr.info.info = (long) info;
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err = skel_sys_bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr));
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if (!err)
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*info_len = attr.info.info_len;
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return err;
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}
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static int send_link_to_kernel(int link_fd, const char *link_name)
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{
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struct bpf_preload_info obj = {};
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struct bpf_link_info info = {};
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__u32 info_len = sizeof(info);
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int err;
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err = __bpf_obj_get_info_by_fd(link_fd, &info, &info_len);
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if (err)
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return err;
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obj.link_id = info.id;
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if (strlen(link_name) >= sizeof(obj.link_name))
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return -E2BIG;
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strcpy(obj.link_name, link_name);
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if (write(to_kernel, &obj, sizeof(obj)) != sizeof(obj))
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return -EPIPE;
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return 0;
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}
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int main(int argc, char **argv)
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{
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struct iterators_bpf *skel;
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int err, magic;
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int debug_fd;
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debug_fd = open("/dev/console", O_WRONLY | O_NOCTTY | O_CLOEXEC);
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if (debug_fd < 0)
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return 1;
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to_kernel = dup(1);
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close(1);
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dup(debug_fd);
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/* now stdin and stderr point to /dev/console */
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read(from_kernel, &magic, sizeof(magic));
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if (magic != BPF_PRELOAD_START) {
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printf("bad start magic %d\n", magic);
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return 1;
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}
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/* libbpf opens BPF object and loads it into the kernel */
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skel = iterators_bpf__open_and_load();
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if (!skel) {
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/* iterators.skel.h is little endian.
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* libbpf doesn't support automatic little->big conversion
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* of BPF bytecode yet.
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* The program load will fail in such case.
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*/
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printf("Failed load could be due to wrong endianness\n");
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return 1;
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}
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err = iterators_bpf__attach(skel);
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if (err)
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goto cleanup;
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/* send two bpf_link IDs with names to the kernel */
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err = send_link_to_kernel(skel->links.dump_bpf_map_fd, "maps.debug");
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if (err)
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goto cleanup;
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err = send_link_to_kernel(skel->links.dump_bpf_prog_fd, "progs.debug");
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if (err)
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goto cleanup;
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/* The kernel will proceed with pinnging the links in bpffs.
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* UMD will wait on read from pipe.
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*/
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read(from_kernel, &magic, sizeof(magic));
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if (magic != BPF_PRELOAD_END) {
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printf("bad final magic %d\n", magic);
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err = -EINVAL;
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}
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cleanup:
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iterators_bpf__destroy(skel);
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return err != 0;
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}
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