Commit 6b0a249a authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov

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: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200821184418.574122-1-yhs@fb.com
parent 149cb339
......@@ -1218,12 +1218,18 @@ typedef int (*bpf_iter_attach_target_t)(struct bpf_prog *prog,
union bpf_iter_link_info *linfo,
struct bpf_iter_aux_info *aux);
typedef void (*bpf_iter_detach_target_t)(struct bpf_iter_aux_info *aux);
typedef void (*bpf_iter_show_fdinfo_t) (const struct bpf_iter_aux_info *aux,
struct seq_file *seq);
typedef int (*bpf_iter_fill_link_info_t)(const struct bpf_iter_aux_info *aux,
struct bpf_link_info *info);
#define BPF_ITER_CTX_ARG_MAX 2
struct bpf_iter_reg {
const char *target;
bpf_iter_attach_target_t attach_target;
bpf_iter_detach_target_t detach_target;
bpf_iter_show_fdinfo_t show_fdinfo;
bpf_iter_fill_link_info_t fill_link_info;
u32 ctx_arg_info_size;
struct bpf_ctx_arg_aux ctx_arg_info[BPF_ITER_CTX_ARG_MAX];
const struct bpf_iter_seq_info *seq_info;
......
......@@ -4071,6 +4071,13 @@ struct bpf_link_info {
__u64 cgroup_id;
__u32 attach_type;
} cgroup;
struct {
__aligned_u64 target_name; /* in/out: target_name buffer ptr */
__u32 target_name_len; /* in/out: target_name buffer len */
union {
__u32 map_id;
} map;
} iter;
struct {
__u32 netns_ino;
__u32 attach_type;
......
......@@ -377,10 +377,68 @@ static int bpf_iter_link_replace(struct bpf_link *link,
return ret;
}
static void bpf_iter_link_show_fdinfo(const struct bpf_link *link,
struct seq_file *seq)
{
struct bpf_iter_link *iter_link =
container_of(link, struct bpf_iter_link, link);
bpf_iter_show_fdinfo_t show_fdinfo;
seq_printf(seq,
"target_name:\t%s\n",
iter_link->tinfo->reg_info->target);
show_fdinfo = iter_link->tinfo->reg_info->show_fdinfo;
if (show_fdinfo)
show_fdinfo(&iter_link->aux, seq);
}
static int bpf_iter_link_fill_link_info(const struct bpf_link *link,
struct bpf_link_info *info)
{
struct bpf_iter_link *iter_link =
container_of(link, struct bpf_iter_link, link);
char __user *ubuf = u64_to_user_ptr(info->iter.target_name);
bpf_iter_fill_link_info_t fill_link_info;
u32 ulen = info->iter.target_name_len;
const char *target_name;
u32 target_len;
if (!ulen ^ !ubuf)
return -EINVAL;
target_name = iter_link->tinfo->reg_info->target;
target_len = strlen(target_name);
info->iter.target_name_len = target_len + 1;
if (ubuf) {
if (ulen >= target_len + 1) {
if (copy_to_user(ubuf, target_name, target_len + 1))
return -EFAULT;
} else {
char zero = '\0';
if (copy_to_user(ubuf, target_name, ulen - 1))
return -EFAULT;
if (put_user(zero, ubuf + ulen - 1))
return -EFAULT;
return -ENOSPC;
}
}
fill_link_info = iter_link->tinfo->reg_info->fill_link_info;
if (fill_link_info)
return fill_link_info(&iter_link->aux, info);
return 0;
}
static const struct bpf_link_ops bpf_iter_link_lops = {
.release = bpf_iter_link_release,
.dealloc = bpf_iter_link_dealloc,
.update_prog = bpf_iter_link_replace,
.show_fdinfo = bpf_iter_link_show_fdinfo,
.fill_link_info = bpf_iter_link_fill_link_info,
};
bool bpf_link_is_iter(struct bpf_link *link)
......
......@@ -4071,6 +4071,13 @@ struct bpf_link_info {
__u64 cgroup_id;
__u32 attach_type;
} cgroup;
struct {
__aligned_u64 target_name; /* in/out: target_name buffer ptr */
__u32 target_name_len; /* in/out: target_name buffer len */
union {
__u32 map_id;
} map;
} iter;
struct {
__u32 netns_ino;
__u32 attach_type;
......
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