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Message-Id: <1287982750-24083-1-git-send-email-x@jeffhansen.com>
Date: Mon, 25 Oct 2010 04:59:10 +0000
From: Jeff Hansen <x@...fhansen.com>
To: netdev@...r.kernel.org
Cc: x@...fhansen.com, Dave Miller <davem@...emloft.net>
Subject: [PATCH] net/unix: Allow Unix sockets to be treated like normal files. (round 2)
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@...fhansen.com>
---
net/unix/Kconfig | 10 +++++
net/unix/af_unix.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 114 insertions(+), 0 deletions(-)
diff --git a/net/unix/Kconfig b/net/unix/Kconfig
index 5a69733..68df4f1 100644
--- a/net/unix/Kconfig
+++ b/net/unix/Kconfig
@@ -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.
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 0ebc777..feb5877 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -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;
--
1.7.0.4
--
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