| 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
| ||
|
Message-Id: <1485975645-8437-1-git-send-email-avagin@openvz.org>
Date: Wed, 1 Feb 2017 11:00:45 -0800
From: Andrei Vagin <avagin@...nvz.org>
To: "David S. Miller" <davem@...emloft.net>
Cc: netdev@...r.kernel.org, criu@...nvz.org,
Andrei Vagin <avagin@...nvz.org>
Subject: [PATCH net-next] unix: add ioctl to open a unix socket file with O_PATH
This ioctl opens a file to which a socket is bound and
returns a file descriptor. The caller has to have CAP_NET_ADMIN
in the socket network namespace.
Currently it is impossible to get a path and a mount point
for a socket file. socket_diag reports address, device ID and inode
number for unix sockets. An address can contain a relative path or
a file may be moved somewhere. And these properties say nothing about
a mount namespace and a mount point of a socket file.
With the introduced ioctl, we can get a path by reading
/proc/self/fd/X and get mnt_id from /proc/self/fdinfo/X.
In CRIU we are going to use this ioctl to dump and restore unix socket.
Here is an example how it can be used:
$ strace -e socket,bind,ioctl ./test /tmp/test_sock
socket(AF_UNIX, SOCK_STREAM, 0) = 3
bind(3, {sa_family=AF_UNIX, sun_path="test_sock"}, 11) = 0
ioctl(3, SIOCUNIXFILE, 0) = 4
^Z
$ ss -a | grep test_sock
u_str LISTEN 0 1 test_sock 17798 * 0
$ ls -l /proc/760/fd/{3,4}
lrwx------ 1 root root 64 Feb 1 09:41 3 -> 'socket:[17798]'
l--------- 1 root root 64 Feb 1 09:41 4 -> /tmp/test_sock
$ cat /proc/760/fdinfo/4
pos: 0
flags: 012000000
mnt_id: 40
$ cat /proc/self/mountinfo | grep "^40\s"
40 19 0:37 / /tmp rw shared:23 - tmpfs tmpfs rw
Signed-off-by: Andrei Vagin <avagin@...nvz.org>
---
include/uapi/linux/un.h | 2 ++
net/unix/af_unix.c | 41 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/include/uapi/linux/un.h b/include/uapi/linux/un.h
index 3ed3e46..4f0ab3a 100644
--- a/include/uapi/linux/un.h
+++ b/include/uapi/linux/un.h
@@ -10,4 +10,6 @@ struct sockaddr_un {
char sun_path[UNIX_PATH_MAX]; /* pathname */
};
+#define SIOCUNIXFILE (SIOCPROTOPRIVATE + 0) /* open a socket file with O_PATH */
+
#endif /* _LINUX_UN_H */
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index cef7987..e2d18b9 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -117,6 +117,7 @@
#include <net/checksum.h>
#include <linux/security.h>
#include <linux/freezer.h>
+#include <linux/file.h>
struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];
EXPORT_SYMBOL_GPL(unix_socket_table);
@@ -2592,6 +2593,43 @@ long unix_outq_len(struct sock *sk)
}
EXPORT_SYMBOL_GPL(unix_outq_len);
+static int unix_open_file(struct sock *sk)
+{
+ struct path path;
+ struct file *f;
+ int fd;
+
+ if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
+ return -EPERM;
+
+ unix_state_lock(sk);
+ path = unix_sk(sk)->path;
+ if (!path.dentry) {
+ unix_state_unlock(sk);
+ return -ENOENT;
+ }
+
+ path_get(&path);
+ unix_state_unlock(sk);
+
+ fd = get_unused_fd_flags(O_CLOEXEC);
+ if (fd < 0)
+ goto out;
+
+ f = dentry_open(&path, O_PATH, current_cred());
+ if (IS_ERR(f)) {
+ put_unused_fd(fd);
+ fd = PTR_ERR(f);
+ goto out;
+ }
+
+ fd_install(fd, f);
+out:
+ path_put(&path);
+
+ return fd;
+}
+
static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
struct sock *sk = sock->sk;
@@ -2610,6 +2648,9 @@ static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
else
err = put_user(amount, (int __user *)arg);
break;
+ case SIOCUNIXFILE:
+ err = unix_open_file(sk);
+ break;
default:
err = -ENOIOCTLCMD;
break;
--
2.7.4
Powered by blists - more mailing lists