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Message-ID: <20200821184418.574122-1-yhs@fb.com>
Date: Fri, 21 Aug 2020 11:44:18 -0700
From: Yonghong Song <yhs@...com>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>
CC: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>
Subject: [PATCH bpf-next v4 1/3] 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@...com>
---
include/linux/bpf.h | 6 ++++
include/uapi/linux/bpf.h | 7 ++++
kernel/bpf/bpf_iter.c | 58 ++++++++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 7 ++++
4 files changed, 78 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a9b7185a6b37..529e9b183eeb 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -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;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 0480f893facd..a1bbaff7a0af 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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;
diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
index b6715964b685..aeec7e174188 100644
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -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)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 0480f893facd..a1bbaff7a0af 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -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;
--
2.24.1
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