A new bpf command BPF_ITER_CREATE is added.
The anonymous bpf iterator is seq_file based.
The seq_file private data are referenced by targets.
The bpf_iter infrastructure allocated additional space
at seq_file->private after the space used by targets
to store some meta data, e.g.,
prog: prog to run
session_id: an unique id for each opened seq_file
seq_num: how many times bpf programs are queried in this session
has_last: indicate whether or not bpf_prog has been called after
all valid objects have been processed
A map between file and prog/link is established to help
fops->release(). When fops->release() is called, just based on
inode and file, bpf program cannot be located since target
seq_priv_size not available. This map helps retrieve the prog
whose reference count needs to be decremented.
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
include/linux/bpf.h | 3 +
include/uapi/linux/bpf.h | 6 ++
kernel/bpf/bpf_iter.c | 162 ++++++++++++++++++++++++++++++++-
kernel/bpf/syscall.c | 27 ++++++
tools/include/uapi/linux/bpf.h | 6 ++
5 files changed, 203 insertions(+), 1 deletion(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 4fc39d9b5cd0..0f0cafc65a04 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1112,6 +1112,8 @@ struct bpf_link *bpf_link_get_from_fd(u32 ufd);
int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
int bpf_obj_get_user(const char __user *pathname, int flags);
+#define BPF_DUMP_SEQ_NET_PRIVATE BIT(0)
+
struct bpf_iter_reg {
const char *target;
const char *target_func_name;
@@ -1133,6 +1135,7 @@ int bpf_iter_run_prog(struct bpf_prog *prog, void *ctx);
int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
int bpf_iter_link_replace(struct bpf_link *link, struct bpf_prog *old_prog,
struct bpf_prog *new_prog);
+int bpf_iter_new_fd(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);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f39b9fec37ab..576651110d16 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -113,6 +113,7 @@ enum bpf_cmd {
BPF_MAP_DELETE_BATCH,
BPF_LINK_CREATE,
BPF_LINK_UPDATE,
+ BPF_ITER_CREATE,
};
enum bpf_map_type {
@@ -590,6 +591,11 @@ union bpf_attr {
__u32 old_prog_fd;
} link_update;
+ struct { /* struct used by BPF_ITER_CREATE command */
+ __u32 link_fd;
+ __u32 flags;
+ } iter_create;
+
} __attribute__((aligned(8)));
/* The description below is an attempt at providing documentation to eBPF
diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
index fc1ce5ee5c3f..1f4e778d1814 100644
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -2,6 +2,7 @@
/* Copyright (c) 2020 Facebook */
#include <linux/fs.h>
+#include <linux/anon_inodes.h>
#include <linux/filter.h>
#include <linux/bpf.h>
@@ -19,6 +20,19 @@ struct bpf_iter_link {
struct bpf_iter_target_info *tinfo;
};
+struct extra_priv_data {
+ struct bpf_prog *prog;
+ u64 session_id;
+ u64 seq_num;
+ bool has_last;
+};
+
+struct anon_file_prog_assoc {
+ struct list_head list;
+ struct file *file;
+ struct bpf_prog *prog;
+};
+
static struct list_head targets;
static struct mutex targets_mutex;
static bool bpf_iter_inited = false;
@@ -26,6 +40,50 @@ static bool bpf_iter_inited = false;
/* protect bpf_iter_link.link->prog upddate */
static struct mutex bpf_iter_mutex;
+/* Since at anon seq_file release function, the prog cannot
+ * be retrieved since target seq_priv_size is not available.
+ * Keep a list of <anon_file, prog> mapping, so that
+ * at file release stage, the prog can be released properly.
+ */
+static struct list_head anon_iter_info;
+static struct mutex anon_iter_info_mutex;
+
+/* incremented on every opened seq_file */
+static atomic64_t session_id;
+
+static u32 get_total_priv_dsize(u32 old_size)
+{
+ return roundup(old_size, 8) + sizeof(struct extra_priv_data);
+}
+
+static void *get_extra_priv_dptr(void *old_ptr, u32 old_size)
+{
+ return old_ptr + roundup(old_size, 8);
+}
+
+static int anon_iter_release(struct inode *inode, struct file *file)
+{
+ struct anon_file_prog_assoc *finfo;
+
+ mutex_lock(&anon_iter_info_mutex);
+ list_for_each_entry(finfo, &anon_iter_info, list) {
+ if (finfo->file == file) {
