@@ -19,3 +19,13 @@ config UNIX
Say Y unless you know what you are doing.
+config UNIX_FOPS
+ boolean "Allow Unix sockets to be treated like normal files"
+ depends on UNIX
+ ---help---
+ If you say Y here, Unix sockets may be opened, written, read, and
+ closed, like normal files. This is handy for sending short commands
+ to Unix sockets (i.e. from shell scripts), without having to create
+ a Unix socket.
+
+ Say Y unless you know what you are doing.
@@ -798,6 +798,105 @@ fail:
return NULL;
}
+#ifdef CONFIG_UNIX_FOPS
+static int unix_open(struct inode *inode, struct file *filp)
+{
+ int err;
+ struct socket *sock = NULL;
+ struct dentry *dentry = filp->f_dentry;
+ struct sockaddr_un sunaddr = { 0 };
+ char *p;
+
+ if (!filp)
+ return -ENXIO;
+ dentry = filp->f_dentry;
+
+ if (!dentry || !dentry->d_parent)
+ return -ENXIO;
+
+ if (filp->private_data)
+ return -EBUSY;
+
+ sunaddr.sun_family = AF_UNIX;
+ p = d_path(&filp->f_path, sunaddr.sun_path, sizeof(sunaddr.sun_path));
+ if (IS_ERR(p))
+ return PTR_ERR(p);
+ memmove(sunaddr.sun_path, p, p[sizeof(sunaddr.sun_path) - 1] ?
+ sizeof(sunaddr.sun_path) : strlen(p));
+
+ err = sock_create(PF_UNIX, SOCK_DGRAM, 0, &sock);
+ if (err)
+ return err;
+
+ err = unix_dgram_connect(sock, (struct sockaddr *)&sunaddr,
+ sizeof(sunaddr), 0);
+ if (err) {
+ sock_release(sock);
+
+ err = sock_create(PF_UNIX, SOCK_STREAM, 0, &sock);
+ if (err)
+ return err;
+
+ err = unix_stream_connect(sock, (struct sockaddr *)&sunaddr,
+ sizeof(sunaddr), 0);
+
+ if (err)
+ return err;
+ }
+ filp->private_data = sock;
+
+ return err;
+}
+
+static int unix_frelease(struct inode *inode, struct file *filp)
+{
+ if (!filp->private_data)
+ return -ENXIO;
+
+ sock_release(filp->private_data);
+ filp->private_data = NULL;
+ return 0;
+}
+
+#define DECLARE_UNIX_FOP(name, buf_mod, fop) \
+static ssize_t name(struct file *filp, buf_mod char __user *buf, \
+ size_t _len, loff_t *ppos) \
+{ \
+ struct socket *sock = filp->private_data; \
+ int len = (int)_len, err; \
+ struct kvec iov = { \
+ .iov_base = (void *)buf, \
+ .iov_len = len, \
+ }; \
+ struct msghdr msg = { \
+ /* NB: struct iovec and kvec are equal */ \
+ .msg_iov = (struct iovec *)&iov, \
+ .msg_iovlen = 1, \
+ }; \
+\
+ if (!sock) \
+ return -ENXIO; \
+ if (_len > 0xffffffffLL) \
+ return -E2BIG; \
+\
+ err = fop; \
+ if (err > 0 && ppos) \
+ *ppos += err; \
+\
+ return err; \
+}
+
+DECLARE_UNIX_FOP(unix_write, const, sock_sendmsg(sock, &msg, len))
+DECLARE_UNIX_FOP(unix_read, , sock_recvmsg(sock, &msg, len, 0))
+
+const struct file_operations unix_sock_fops = {
+ .owner = THIS_MODULE,
+ .open = unix_open,
+ .release = unix_frelease,
+ .write = unix_write,
+ .read = unix_read,
+};
+#endif /* CONFIG_UNIX_FOPS */
static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
@@ -874,6 +973,11 @@ out_mknod_drop_write:
mnt_drop_write(nd.path.mnt);
if (err)
goto out_mknod_dput;
+
+#ifdef CONFIG_UNIX_FOPS
+ dentry->d_inode->i_fop = &unix_sock_fops;
+#endif
+
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
dput(nd.path.dentry);
nd.path.dentry = dentry;
This allows Unix sockets to be opened, written, read, and closed, like normal files. This can be especially handy from, for example, a shell script that wants to send a short message to a Unix socket, but doesn't want to and/or cannot create the socket itself. This will try to open the Unix socket first in SOCK_DGRAM mode, then SOCK_STREAM mode if that fails. Signed-off-by: Jeff Hansen <x@jeffhansen.com> --- net/unix/Kconfig | 10 +++++ net/unix/af_unix.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 114 insertions(+), 0 deletions(-)