From: Yonghong Song <yhs@fb.com>
Date: Sat, 9 May 2020 10:59:06 -0700
Subject: bpf: Create file bpf iterator
Patch-mainline: v5.8-rc1
Git-commit: 367ec3e4834cbd611401c2c40a23c22c825474f1
References: bsc#1177028
To produce a file bpf iterator, the fd must be
corresponding to a link_fd assocciated with a
trace/iter program. When the pinned file is
opened, a seq_file will be generated.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175906.2475893-1-yhs@fb.com
Acked-by: Gary Lin <glin@suse.com>
---
include/linux/bpf.h | 2 ++
kernel/bpf/bpf_iter.c | 17 ++++++++++++++++-
kernel/bpf/inode.c | 5 ++++-
3 files changed, 22 insertions(+), 2 deletions(-)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1022,6 +1022,7 @@ static inline void bpf_enable_instrument
extern const struct file_operations bpf_map_fops;
extern const struct file_operations bpf_prog_fops;
+extern const struct file_operations bpf_iter_fops;
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
extern const struct bpf_prog_ops _name ## _prog_ops; \
@@ -1145,6 +1146,7 @@ void bpf_iter_unreg_target(const char *t
bool bpf_iter_prog_supported(struct bpf_prog *prog);
int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
int bpf_iter_new_fd(struct bpf_link *link);
+bool bpf_link_is_iter(struct bpf_link *link);
int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -39,6 +39,8 @@ static DEFINE_MUTEX(link_mutex);
/* incremented on every opened seq_file */
static atomic64_t session_id;
+static int prepare_seq_file(struct file *file, struct bpf_iter_link *link);
+
/* bpf_seq_read, a customized and simpler version for bpf iterator.
* no_llseek is assumed for this file.
* The following are differences from seq_read():
@@ -162,6 +164,13 @@ done:
return copied;
}
+static int iter_open(struct inode *inode, struct file *file)
+{
+ struct bpf_iter_link *link = inode->i_private;
+
+ return prepare_seq_file(file, link);
+}
+
static int iter_release(struct inode *inode, struct file *file)
{
struct bpf_iter_priv_data *iter_priv;
@@ -183,7 +192,8 @@ static int iter_release(struct inode *in
return seq_release_private(inode, file);
}
-static const struct file_operations bpf_iter_fops = {
+const struct file_operations bpf_iter_fops = {
+ .open = iter_open,
.llseek = no_llseek,
.read = bpf_seq_read,
.release = iter_release,
@@ -310,6 +320,11 @@ static const struct bpf_link_ops bpf_ite
.update_prog = bpf_iter_link_replace,
};
+bool bpf_link_is_iter(struct bpf_link *link)
+{
+ return link->ops == &bpf_iter_link_lops;
+}
+
int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
struct bpf_link_primer link_primer;
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -358,8 +358,11 @@ static int bpf_mkmap(struct dentry *dent
static int bpf_mklink(struct dentry *dentry, umode_t mode, void *arg)
{
+ struct bpf_link *link = arg;
+
return bpf_mkobj_ops(dentry, mode, arg, &bpf_link_iops,
- &bpffs_obj_fops);
+ bpf_link_is_iter(link) ?
+ &bpf_iter_fops : &bpffs_obj_fops);
}
static struct dentry *