kernel/bpf/link_iter.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* Copyright (c) 2022 Red Hat, Inc. */
0003 #include <linux/bpf.h>
0004 #include <linux/fs.h>
0005 #include <linux/filter.h>
0006 #include <linux/kernel.h>
0007 #include <linux/btf_ids.h>
0008
0009 struct bpf_iter_seq_link_info {
0010     u32 link_id;
0011 };
0012
0013 static void *bpf_link_seq_start(struct seq_file *seq, loff_t *pos)
0014 {
0015     struct bpf_iter_seq_link_info *info = seq->private;
0016     struct bpf_link *link;
0017
0018     link = bpf_link_get_curr_or_next(&info->link_id);
0019     if (!link)
0020         return NULL;
0021
0022     if (*pos == 0)
0023         ++*pos;
0024     return link;
0025 }
0026
0027 static void *bpf_link_seq_next(struct seq_file *seq, void *v, loff_t *pos)
0028 {
0029     struct bpf_iter_seq_link_info *info = seq->private;
0030
0031     ++*pos;
0032     ++info->link_id;
0033     bpf_link_put((struct bpf_link *)v);
0034     return bpf_link_get_curr_or_next(&info->link_id);
0035 }
0036
0037 struct bpf_iter__bpf_link {
0038     __bpf_md_ptr(struct bpf_iter_meta *, meta);
0039     __bpf_md_ptr(struct bpf_link *, link);
0040 };
0041
0042 DEFINE_BPF_ITER_FUNC(bpf_link, struct bpf_iter_meta *meta, struct bpf_link *link)
0043
0044 static int __bpf_link_seq_show(struct seq_file *seq, void *v, bool in_stop)
0045 {
0046     struct bpf_iter__bpf_link ctx;
0047     struct bpf_iter_meta meta;
0048     struct bpf_prog *prog;
0049     int ret = 0;
0050
0051     ctx.meta = &meta;
0052     ctx.link = v;
0053     meta.seq = seq;
0054     prog = bpf_iter_get_info(&meta, in_stop);
0055     if (prog)
0056         ret = bpf_iter_run_prog(prog, &ctx);
0057
0058     return ret;
0059 }
0060
0061 static int bpf_link_seq_show(struct seq_file *seq, void *v)
0062 {
0063     return __bpf_link_seq_show(seq, v, false);
0064 }
0065
0066 static void bpf_link_seq_stop(struct seq_file *seq, void *v)
0067 {
0068     if (!v)
0069         (void)__bpf_link_seq_show(seq, v, true);
0070     else
0071         bpf_link_put((struct bpf_link *)v);
0072 }
0073
0074 static const struct seq_operations bpf_link_seq_ops = {
0075     .start  = bpf_link_seq_start,
0076     .next   = bpf_link_seq_next,
0077     .stop   = bpf_link_seq_stop,
0078     .show   = bpf_link_seq_show,
0079 };
0080
0081 BTF_ID_LIST(btf_bpf_link_id)
0082 BTF_ID(struct, bpf_link)
0083
0084 static const struct bpf_iter_seq_info bpf_link_seq_info = {
0085     .seq_ops        = &bpf_link_seq_ops,
0086     .init_seq_private   = NULL,
0087     .fini_seq_private   = NULL,
0088     .seq_priv_size      = sizeof(struct bpf_iter_seq_link_info),
0089 };
0090
0091 static struct bpf_iter_reg bpf_link_reg_info = {
0092     .target         = "bpf_link",
0093     .ctx_arg_info_size  = 1,
0094     .ctx_arg_info       = {
0095         { offsetof(struct bpf_iter__bpf_link, link),
0096           PTR_TO_BTF_ID_OR_NULL },
0097     },
0098     .seq_info       = &bpf_link_seq_info,
0099 };
0100
0101 static int __init bpf_link_iter_init(void)
0102 {
0103     bpf_link_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_link_id;
0104     return bpf_iter_reg_target(&bpf_link_reg_info);
0105 }
0106
0107 late_initcall(bpf_link_iter_init);