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bpf: Implement link_query for bpf iterators
This patch implemented bpf_link callback functions show_fdinfo and fill_link_info to support link_query interface. The general interface for show_fdinfo and fill_link_info will print/fill the target_name. Each targets can register show_fdinfo and fill_link_info callbacks to print/fill more target specific information. For example, the below is a fdinfo result for a bpf task iterator. $ cat /proc/1749/fdinfo/7 pos: 0 flags: 02000000 mnt_id: 14 link_type: iter link_id: 11 prog_tag: 990e1f8152f7e54f prog_id: 59 target_name: task Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200821184418.574122-1-yhs@fb.com
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149cb33955
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4 changed files with 78 additions and 0 deletions
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@ -1218,12 +1218,18 @@ typedef int (*bpf_iter_attach_target_t)(struct bpf_prog *prog,
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union bpf_iter_link_info *linfo,
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struct bpf_iter_aux_info *aux);
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typedef void (*bpf_iter_detach_target_t)(struct bpf_iter_aux_info *aux);
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typedef void (*bpf_iter_show_fdinfo_t) (const struct bpf_iter_aux_info *aux,
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struct seq_file *seq);
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typedef int (*bpf_iter_fill_link_info_t)(const struct bpf_iter_aux_info *aux,
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struct bpf_link_info *info);
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#define BPF_ITER_CTX_ARG_MAX 2
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struct bpf_iter_reg {
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const char *target;
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bpf_iter_attach_target_t attach_target;
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bpf_iter_detach_target_t detach_target;
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bpf_iter_show_fdinfo_t show_fdinfo;
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bpf_iter_fill_link_info_t fill_link_info;
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u32 ctx_arg_info_size;
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struct bpf_ctx_arg_aux ctx_arg_info[BPF_ITER_CTX_ARG_MAX];
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const struct bpf_iter_seq_info *seq_info;
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@ -4071,6 +4071,13 @@ struct bpf_link_info {
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__u64 cgroup_id;
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__u32 attach_type;
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} cgroup;
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struct {
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__aligned_u64 target_name; /* in/out: target_name buffer ptr */
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__u32 target_name_len; /* in/out: target_name buffer len */
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union {
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__u32 map_id;
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} map;
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} iter;
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struct {
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__u32 netns_ino;
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__u32 attach_type;
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@ -377,10 +377,68 @@ static int bpf_iter_link_replace(struct bpf_link *link,
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return ret;
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}
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static void bpf_iter_link_show_fdinfo(const struct bpf_link *link,
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struct seq_file *seq)
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{
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struct bpf_iter_link *iter_link =
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container_of(link, struct bpf_iter_link, link);
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bpf_iter_show_fdinfo_t show_fdinfo;
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seq_printf(seq,
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"target_name:\t%s\n",
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iter_link->tinfo->reg_info->target);
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show_fdinfo = iter_link->tinfo->reg_info->show_fdinfo;
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if (show_fdinfo)
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show_fdinfo(&iter_link->aux, seq);
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}
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static int bpf_iter_link_fill_link_info(const struct bpf_link *link,
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struct bpf_link_info *info)
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{
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struct bpf_iter_link *iter_link =
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container_of(link, struct bpf_iter_link, link);
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char __user *ubuf = u64_to_user_ptr(info->iter.target_name);
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bpf_iter_fill_link_info_t fill_link_info;
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u32 ulen = info->iter.target_name_len;
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const char *target_name;
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u32 target_len;
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if (!ulen ^ !ubuf)
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return -EINVAL;
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target_name = iter_link->tinfo->reg_info->target;
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target_len = strlen(target_name);
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info->iter.target_name_len = target_len + 1;
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if (ubuf) {
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if (ulen >= target_len + 1) {
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if (copy_to_user(ubuf, target_name, target_len + 1))
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return -EFAULT;
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} else {
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char zero = '\0';
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if (copy_to_user(ubuf, target_name, ulen - 1))
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return -EFAULT;
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if (put_user(zero, ubuf + ulen - 1))
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return -EFAULT;
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return -ENOSPC;
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}
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}
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fill_link_info = iter_link->tinfo->reg_info->fill_link_info;
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if (fill_link_info)
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return fill_link_info(&iter_link->aux, info);
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return 0;
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}
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static const struct bpf_link_ops bpf_iter_link_lops = {
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.release = bpf_iter_link_release,
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.dealloc = bpf_iter_link_dealloc,
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.update_prog = bpf_iter_link_replace,
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.show_fdinfo = bpf_iter_link_show_fdinfo,
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.fill_link_info = bpf_iter_link_fill_link_info,
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};
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bool bpf_link_is_iter(struct bpf_link *link)
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@ -4071,6 +4071,13 @@ struct bpf_link_info {
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__u64 cgroup_id;
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__u32 attach_type;
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} cgroup;
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struct {
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__aligned_u64 target_name; /* in/out: target_name buffer ptr */
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__u32 target_name_len; /* in/out: target_name buffer len */
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union {
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__u32 map_id;
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} map;
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} iter;
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struct {
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__u32 netns_ino;
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__u32 attach_type;
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