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When pinning programs/objects under PATH (eg: during "bpftool prog
loadall") the bpffs is mounted on the parent dir of PATH in the
following situations:
- the given dir exists but it is not bpffs.
- the given dir doesn't exist and the parent dir is not bpffs.
Mounting on the parent dir can also have the unintentional side-
effect of hiding other files located under the parent dir.
If the given dir exists but is not bpffs, then the bpffs should
be mounted on the given dir and not its parent dir.
Similarly, if the given dir doesn't exist and its parent dir is not
bpffs, then the given dir should be created and the bpffs should be
mounted on this new dir.
Fixes: 2a36c26fe3 ("bpftool: Support bpffs mountpoint as pin path for prog loadall")
Signed-off-by: Sahil Siddiq <icegambit91@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/2da44d24-74ae-a564-1764-afccf395eeec@isovalent.com/T/#t
Link: https://lore.kernel.org/bpf/20240404192219.52373-1-icegambit91@gmail.com
Closes: https://github.com/libbpf/bpftool/issues/100
Changes since v1:
- Split "mount_bpffs_for_pin" into two functions.
This is done to improve maintainability and readability.
Changes since v2:
- mount_bpffs_for_pin: rename to "create_and_mount_bpffs_dir".
- mount_bpffs_given_file: rename to "mount_bpffs_given_file".
- create_and_mount_bpffs_dir:
- introduce "dir_exists" boolean.
- remove new dir if "mnt_fs" fails.
- improve error handling and error messages.
Changes since v3:
- Rectify function name.
- Improve error messages and formatting.
- mount_bpffs_for_file:
- Check if dir exists before block_mount check.
Changes since v4:
- Use strdup instead of strcpy.
- create_and_mount_bpffs_dir:
- Use S_IRWXU instead of 0700.
- Improve error handling and formatting.
124 lines
2.3 KiB
C
124 lines
2.3 KiB
C
// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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// Copyright (C) 2020 Facebook
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#ifndef _GNU_SOURCE
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#define _GNU_SOURCE
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#endif
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#include <errno.h>
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#include <unistd.h>
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#include <linux/err.h>
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#include <bpf/libbpf.h>
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#include "main.h"
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static int do_pin(int argc, char **argv)
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{
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DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, iter_opts);
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union bpf_iter_link_info linfo;
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const char *objfile, *path;
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struct bpf_program *prog;
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struct bpf_object *obj;
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struct bpf_link *link;
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int err = -1, map_fd = -1;
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if (!REQ_ARGS(2))
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usage();
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objfile = GET_ARG();
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path = GET_ARG();
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/* optional arguments */
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if (argc) {
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if (is_prefix(*argv, "map")) {
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NEXT_ARG();
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if (!REQ_ARGS(2)) {
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p_err("incorrect map spec");
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return -1;
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}
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map_fd = map_parse_fd(&argc, &argv);
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if (map_fd < 0)
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return -1;
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memset(&linfo, 0, sizeof(linfo));
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linfo.map.map_fd = map_fd;
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iter_opts.link_info = &linfo;
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iter_opts.link_info_len = sizeof(linfo);
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}
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}
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obj = bpf_object__open(objfile);
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if (!obj) {
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err = -errno;
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p_err("can't open objfile %s", objfile);
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goto close_map_fd;
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}
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err = bpf_object__load(obj);
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if (err) {
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p_err("can't load objfile %s", objfile);
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goto close_obj;
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}
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prog = bpf_object__next_program(obj, NULL);
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if (!prog) {
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err = -errno;
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p_err("can't find bpf program in objfile %s", objfile);
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goto close_obj;
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}
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link = bpf_program__attach_iter(prog, &iter_opts);
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if (!link) {
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err = -errno;
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p_err("attach_iter failed for program %s",
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bpf_program__name(prog));
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goto close_obj;
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}
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err = mount_bpffs_for_file(path);
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if (err)
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goto close_link;
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err = bpf_link__pin(link, path);
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if (err) {
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p_err("pin_iter failed for program %s to path %s",
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bpf_program__name(prog), path);
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goto close_link;
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}
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close_link:
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bpf_link__destroy(link);
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close_obj:
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bpf_object__close(obj);
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close_map_fd:
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if (map_fd >= 0)
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close(map_fd);
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return err;
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}
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static int do_help(int argc, char **argv)
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{
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fprintf(stderr,
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"Usage: %1$s %2$s pin OBJ PATH [map MAP]\n"
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" %1$s %2$s help\n"
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"\n"
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" " HELP_SPEC_MAP "\n"
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" " HELP_SPEC_OPTIONS " }\n"
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"",
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bin_name, "iter");
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return 0;
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}
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static const struct cmd cmds[] = {
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{ "help", do_help },
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{ "pin", do_pin },
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{ 0 }
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};
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int do_iter(int argc, char **argv)
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{
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return cmd_select(cmds, argc, argv, do_help);
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}
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