netdev - [PATCH net-next 1/3] bpf, maps: add release callback

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 15 Jun 2016 22:47:12 +0200
From:	Daniel Borkmann <daniel@...earbox.net>
To:	davem@...emloft.net
Cc:	alexei.starovoitov@...il.com, netdev@...r.kernel.org,
	Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH net-next 1/3] bpf, maps: add release callback

Add a release callback for maps that is invoked when the last
reference to its struct file is gone and the struct file about
to be released by vfs. The handler will be used by fd array maps.

Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Alexei Starovoitov <ast@...nel.org>
---
 include/linux/bpf.h  | 3 ++-
 kernel/bpf/syscall.c | 7 ++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 1bcae82..29b5a1a 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -19,7 +19,8 @@ struct bpf_map;
 struct bpf_map_ops {
 	/* funcs callable from userspace (via syscall) */
 	struct bpf_map *(*map_alloc)(union bpf_attr *attr);
-	void (*map_free)(struct bpf_map *);
+	void (*map_release)(struct bpf_map *map, struct file *map_file);
+	void (*map_free)(struct bpf_map *map);
 	int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
 
 	/* funcs callable from userspace and from eBPF programs */
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 46ecce4..fc3adcd 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -124,7 +124,12 @@ void bpf_map_put_with_uref(struct bpf_map *map)
 
 static int bpf_map_release(struct inode *inode, struct file *filp)
 {
-	bpf_map_put_with_uref(filp->private_data);
+	struct bpf_map *map = filp->private_data;
+
+	if (map->ops->map_release)
+		map->ops->map_release(map, filp);
+
+	bpf_map_put_with_uref(map);
 	return 0;
 }
 
-- 
1.9.3