/*
* Linux WiMAX
* Generic messaging interface between userspace and driver/device
*
*
* Copyright (C) 2007-2008 Intel Corporation <linux-wimax@intel.com>
* Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
*
* This implements a direct communication channel between user space and
* the driver/device, by which free form messages can be sent back and
* forth.
*
* This is intended for device-specific features, vendor quirks, etc.
*
* See include/net/wimax.h
*
* GENERIC NETLINK ENCODING AND CAPACITY
*
* A destination "pipe name" is added to each message; it is up to the
* drivers to assign or use those names (if using them at all).
*
* Messages are encoded as a binary netlink attribute using nla_put()
* using type NLA_UNSPEC (as some versions of libnl still in
* deployment don't yet understand NLA_BINARY).
*
* The maximum capacity of this transport is PAGESIZE per message (so
* the actual payload will be bit smaller depending on the
* netlink/generic netlink attributes and headers).
*
* RECEPTION OF MESSAGES
*
* When a message is received from user space, it is passed verbatim
* to the driver calling wimax_dev->op_msg_from_user(). The return
* value from this function is passed back to user space as an ack
* over the generic netlink protocol.
*
* The stack doesn't do any processing or interpretation of these
* messages.
*
* SENDING MESSAGES
*
* Messages can be sent with wimax_msg().
*
* If the message delivery needs to happen on a different context to
* that of its creation, wimax_msg_alloc() can be used to get a
* pointer to the message that can be delivered later on with
* wimax_msg_send().
*
* ROADMAP
*
* wimax_gnl_doit_msg_from_user() Process a message from user space
* wimax_dev_get_by_genl_info()
* wimax_dev->op_msg_from_user() Delivery of message to the driver
*
* wimax_msg() Send a message to user space
* wimax_msg_alloc()
* wimax_msg_send()
*/
#include <linux/device.h>
#include <linux/slab.h>
#include <net/genetlink.h>
#include <linux/netdevice.h>
#include <linux/wimax.h>
#include <linux/security.h>
#include <linux/export.h>
#include "wimax-internal.h"
#define D_SUBMODULE op_msg
#include "debug-levels.h"
/**
* wimax_msg_alloc - Create a new skb for sending a message to userspace
*
* @wimax_dev: WiMAX device descriptor
* @pipe_name: "named pipe" the message will be sent to
* @msg: pointer to the message data to send
* @size: size of the message to send (in bytes), including the header.
* @gfp_flags: flags for memory allocation.
*
* Returns: %0 if ok, negative errno code on error
*
* Description:
*
* Allocates an skb that will contain the message to send to user
* space over the messaging pipe and initializes it, copying the
* payload.
*
* Once this call is done, you can deliver it with
* wimax_msg_send().
*
* IMPORTANT:
*
* Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
* wimax_msg_send() depends on skb->data being placed at the
* beginning of the user message.
*
* Unlike other WiMAX stack calls, this call can be used way early,
* even before wimax_dev_add() is called, as long as the
* wimax_dev->net_dev pointer is set to point to a proper
* net_dev. This is so that drivers can use it early in case they need
* to send stuff around or communicate with user space.
*/
struct sk_buff *wimax_msg_alloc(struct wimax_dev *wimax_dev,
const char *pipe_name,
const void *msg, size_t size,
gfp_t gfp_flags)
{
int result;
struct device *dev = wimax_dev_to_dev(wimax_dev);
size_t msg_size;
void *genl_msg;
struct sk_buff *skb;
msg_size = nla_total_size(size)
+ nla_total_size(sizeof(u32))
+ (pipe_name ? nla_total_size(strlen(pipe_name)) : 0);
result = -ENOMEM;
skb = genlmsg_new(msg_size, gfp_flags);
if (skb == NULL)
goto error_new;
genl_msg = genlmsg_put(skb, 0, 0, &wimax_gnl_family,
0, WIMAX_GNL_OP_MSG_TO_USER);
if (genl_msg == NULL) {
dev_err(dev, "no memory to create generic netlink message\n");
goto error_genlmsg_put;
}
result = nla_put_u32(skb, WIMAX_GNL_MSG_IFIDX,
wimax_dev->net_dev->ifindex);
if (result < 0) {
dev_err(dev, "no memory to add ifindex attribute\n");
goto error_nla_put;
}
if (pipe_name) {
result = nla_put_string(skb, WIMAX_GNL_MSG_PIPE_NAME,
pipe_name);
if (result < 0) {
dev_err(dev, "no memory to add pipe_name attribute\n");
goto error_nla_put;
}
}
result = nla_put(skb, WIMAX_GNL_MSG_DATA, size, msg);
if (result < 0) {
dev_err(dev, "no memory to add payload (msg %p size %zu) in "
"attribute: %d\n", msg, size, result);
goto error_nla_put;
}
genlmsg_end(skb, genl_msg);
return skb;
error_nla_put:
error_genlmsg_put:
error_new:
nlmsg_free(skb);
return ERR_PTR(result);
}
EXPORT_SYMBOL_GPL(wimax_msg_alloc);
/**
* wimax_msg_data_len - Return a pointer and size of a message's payload
*
* @msg: Pointer to a message created with wimax_msg_alloc()
* @size: Pointer to where to store the message's size
*
* Returns the pointer to the message data.
*/
const void *wimax_msg_data_len(struct sk_buff *msg, size_t *size)
{
struct nlmsghdr *nlh = (void *) msg->head;
struct nlattr *nla;
nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
WIMAX_GNL_MSG_DATA);
if (nla == NULL) {
pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
return NULL;
}
*size = nla_len(nla);
return nla_data(nla);
}
EXPORT_SYMBOL_GPL(wimax_msg_data_len);
/**
* wimax_msg_data - Return a pointer to a message's payload
*
* @msg: Pointer to a message created with wimax_msg_alloc()
*/
const void *wimax_msg_data(struct sk_buff *msg)
{
struct nlmsghdr *nlh = (void *) msg->head;
struct nlattr *nla;
nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
WIMAX_GNL_MSG_DATA);
if (nla == NULL) {
pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
return NULL;
}
return nla_data(nla);
}
EXPORT_SYMBOL_GPL(wimax_msg_data);
/**
* wimax_msg_len - Return a message's payload length
*
* @msg: Pointer to a message created with wimax_msg_alloc()
*/
ssize_t wimax_msg_len(struct sk_buff *msg)
{
struct nlmsghdr *nlh = (void *) msg->head;
struct nlattr *nla;
nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
WIMAX_GNL_MSG_DATA);
if (nla == NULL) {
pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
return -EINVAL;
}
return nla_len(nla);
}
EXPORT_SYMBOL_GPL(wimax_msg_len);
/**
* wimax_msg_send - Send a pre-allocated message to user space
*
* @wimax_dev: WiMAX device descriptor
*
* @skb: &struct sk_buff returned by wimax_msg_alloc(). Note the
* ownership of @skb is transferred to this function.
*
* Returns: 0 if ok, < 0 errno code on error
*
* Description:
*
* Sends a free-form message that was preallocated with
* wimax_msg_alloc() and filled up.
*
* Assumes that once you pass an skb to this function for sending, it
* owns it and will release it when done (on success).
*
* IMPORTANT:
*
* Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
* wimax_msg_send() depends on skb->data being placed at the
* beginning of the user message.
*
* Unlike other WiMAX stack calls, this call can be used way early,
* even before wimax_dev_add() is called, as long as the
* wimax_dev->net_dev pointer is set to point to a proper
* net_dev. This is so that drivers can use it early in case they need
* to send stuff around or communicate with user space.
*/
int wimax_msg_send(struct wimax_dev *wimax_dev, struct sk_buff *skb)
{
struct device *dev = wimax_dev_to_dev(wimax_dev);
void *msg = skb->data;
size_t size = skb->len;
might_sleep();
d_printf(1, dev, "CTX: wimax msg, %zu bytes\n", size);
d_dump(2, dev, msg, size);
genlmsg_multicast(&wimax_gnl_family, skb, 0, 0, GFP_KERNEL);
d_printf(1, dev, "CTX: genl multicast done\n");
return 0;
}
EXPORT_SYMBOL_GPL(wimax_msg_send);
/**
* wimax_msg - Send a message to user space
*
* @wimax_dev: WiMAX device descriptor (properly referenced)
* @pipe_name: "named pipe" the message will be sent to
* @buf: pointer to the message to send.
* @size: size of the buffer pointed to by @buf (in bytes).
* @gfp_flags: flags for memory allocation.
*
* Returns: %0 if ok, negative errno code on error.
*
* Description:
*
* Sends a free-form message to user space on the device @wimax_dev.
*
* NOTES:
*
* Once the @skb is given to this function, who will own it and will
* release it when done (unless it returns error).
*/
int wimax_msg(struct wimax_dev *wimax_dev, const char *pipe_name,
const void *buf, size_t size, gfp_t gfp_flags)
{
int result = -ENOMEM;
struct sk_buff *skb;
skb = wimax_msg_alloc(wimax_dev, pipe_name, buf, size, gfp_flags);
if (IS_ERR(skb))
result = PTR_ERR(skb);
else
result = wimax_msg_send(wimax_dev, skb);
return result;
}
EXPORT_SYMBOL_GPL(wimax_msg);
/*
* Relays a message from user space to the driver
*
* The skb is passed to the driver-specific function with the netlink
* and generic netlink headers already stripped.
*
* This call will block while handling/relaying the message.
*/
int wimax_gnl_doit_msg_from_user(struct sk_buff *skb, struct genl_info *info)
{
int result, ifindex;
struct wimax_dev *wimax_dev;
struct device *dev;
struct nlmsghdr *nlh = info->nlhdr;
char *pipe_name;
void *msg_buf;
size_t msg_len;
might_sleep();
d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
result = -ENODEV;
if (info->attrs[WIMAX_GNL_MSG_IFIDX] == NULL) {
pr_err("WIMAX_GNL_MSG_FROM_USER: can't find IFIDX attribute\n");
goto error_no_wimax_dev;
}
ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_IFIDX]);
wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
if (wimax_dev == NULL)
goto error_no_wimax_dev;
dev = wimax_dev_to_dev(wimax_dev);
/* Unpack arguments */
result = -EINVAL;
if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
"attribute\n");
goto error_no_data;
}
msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);
if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
pipe_name = NULL;
else {
struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
size_t attr_len = nla_len(attr);
/* libnl-1.1 does not yet support NLA_NUL_STRING */
result = -ENOMEM;
pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
if (pipe_name == NULL)
goto error_alloc;
pipe_name[attr_len] = 0;
}
mutex_lock(&wimax_dev->mutex);
result = wimax_dev_is_ready(wimax_dev);
if (result == -ENOMEDIUM)
result = 0;
if (result < 0)
goto error_not_ready;
result = -ENOSYS;
if (wimax_dev->op_msg_from_user == NULL)
goto error_noop;
d_printf(1, dev,
"CRX: nlmsghdr len %u type %u flags 0x%04x seq 0x%x pid %u\n",
nlh->nlmsg_len, nlh->nlmsg_type, nlh->nlmsg_flags,
nlh->nlmsg_seq, nlh->nlmsg_pid);
d_printf(1, dev, "CRX: wimax message %zu bytes\n", msg_len);
d_dump(2, dev, msg_buf, msg_len);
result = wimax_dev->op_msg_from_user(wimax_dev, pipe_name,
msg_buf, msg_len, info);
error_noop:
error_not_ready:
mutex_unlock(&wimax_dev->mutex);
error_alloc:
kfree(pipe_name);
error_no_data:
dev_put(wimax_dev->net_dev);
error_no_wimax_dev:
d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
return result;
}