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9f88361273
Implement bpf_link iterator to traverse links via bpf_seq_file
operations. The changeset is mostly shamelessly copied from
commit a228a64fc1 ("bpf: Add bpf_prog iterator")
Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220510155233.9815-2-9erthalion6@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
107 lines
2.4 KiB
C
107 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2022 Red Hat, Inc. */
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#include <linux/bpf.h>
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#include <linux/fs.h>
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#include <linux/filter.h>
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#include <linux/kernel.h>
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#include <linux/btf_ids.h>
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struct bpf_iter_seq_link_info {
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u32 link_id;
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};
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static void *bpf_link_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct bpf_iter_seq_link_info *info = seq->private;
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struct bpf_link *link;
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link = bpf_link_get_curr_or_next(&info->link_id);
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if (!link)
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return NULL;
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if (*pos == 0)
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++*pos;
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return link;
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}
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static void *bpf_link_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct bpf_iter_seq_link_info *info = seq->private;
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++*pos;
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++info->link_id;
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bpf_link_put((struct bpf_link *)v);
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return bpf_link_get_curr_or_next(&info->link_id);
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}
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struct bpf_iter__bpf_link {
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__bpf_md_ptr(struct bpf_iter_meta *, meta);
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__bpf_md_ptr(struct bpf_link *, link);
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};
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DEFINE_BPF_ITER_FUNC(bpf_link, struct bpf_iter_meta *meta, struct bpf_link *link)
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static int __bpf_link_seq_show(struct seq_file *seq, void *v, bool in_stop)
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{
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struct bpf_iter__bpf_link ctx;
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struct bpf_iter_meta meta;
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struct bpf_prog *prog;
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int ret = 0;
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ctx.meta = &meta;
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ctx.link = v;
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meta.seq = seq;
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prog = bpf_iter_get_info(&meta, in_stop);
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if (prog)
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ret = bpf_iter_run_prog(prog, &ctx);
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return ret;
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}
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static int bpf_link_seq_show(struct seq_file *seq, void *v)
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{
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return __bpf_link_seq_show(seq, v, false);
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}
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static void bpf_link_seq_stop(struct seq_file *seq, void *v)
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{
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if (!v)
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(void)__bpf_link_seq_show(seq, v, true);
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else
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bpf_link_put((struct bpf_link *)v);
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}
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static const struct seq_operations bpf_link_seq_ops = {
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.start = bpf_link_seq_start,
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.next = bpf_link_seq_next,
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.stop = bpf_link_seq_stop,
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.show = bpf_link_seq_show,
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};
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BTF_ID_LIST(btf_bpf_link_id)
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BTF_ID(struct, bpf_link)
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static const struct bpf_iter_seq_info bpf_link_seq_info = {
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.seq_ops = &bpf_link_seq_ops,
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.init_seq_private = NULL,
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.fini_seq_private = NULL,
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.seq_priv_size = sizeof(struct bpf_iter_seq_link_info),
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};
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static struct bpf_iter_reg bpf_link_reg_info = {
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.target = "bpf_link",
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.ctx_arg_info_size = 1,
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.ctx_arg_info = {
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{ offsetof(struct bpf_iter__bpf_link, link),
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PTR_TO_BTF_ID_OR_NULL },
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},
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.seq_info = &bpf_link_seq_info,
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};
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static int __init bpf_link_iter_init(void)
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{
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bpf_link_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_link_id;
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return bpf_iter_reg_target(&bpf_link_reg_info);
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}
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late_initcall(bpf_link_iter_init);
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