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linux/drivers/scsi/scsi_netlink.c

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/*
* scsi_netlink.c - SCSI Transport Netlink Interface
*
* Copyright (C) 2006 James Smart, Emulex Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/time.h>
#include <linux/jiffies.h>
#include <linux/security.h>
#include <linux/delay.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <scsi/scsi_netlink.h>
#include "scsi_priv.h"
struct sock *scsi_nl_sock = NULL;
EXPORT_SYMBOL_GPL(scsi_nl_sock);
static DEFINE_SPINLOCK(scsi_nl_lock);
static struct list_head scsi_nl_drivers;
static u32 scsi_nl_state;
#define STATE_EHANDLER_BSY 0x00000001
struct scsi_nl_transport {
int (*msg_handler)(struct sk_buff *);
void (*event_handler)(struct notifier_block *, unsigned long, void *);
unsigned int refcnt;
int flags;
};
/* flags values (bit flags) */
#define HANDLER_DELETING 0x1
static struct scsi_nl_transport transports[SCSI_NL_MAX_TRANSPORTS] =
{ {NULL, }, };
struct scsi_nl_drvr {
struct list_head next;
int (*dmsg_handler)(struct Scsi_Host *shost, void *payload,
u32 len, u32 pid);
void (*devt_handler)(struct notifier_block *nb,
unsigned long event, void *notify_ptr);
struct scsi_host_template *hostt;
u64 vendor_id;
unsigned int refcnt;
int flags;
};
/**
* scsi_nl_rcv_msg - Receive message handler.
* @skb: socket receive buffer
*
* Description: Extracts message from a receive buffer.
* Validates message header and calls appropriate transport message handler
*
*
**/
static void
scsi_nl_rcv_msg(struct sk_buff *skb)
{
struct nlmsghdr *nlh;
struct scsi_nl_hdr *hdr;
unsigned long flags;
u32 rlen;
int err, tport;
while (skb->len >= NLMSG_SPACE(0)) {
err = 0;
nlh = nlmsg_hdr(skb);
if ((nlh->nlmsg_len < (sizeof(*nlh) + sizeof(*hdr))) ||
(skb->len < nlh->nlmsg_len)) {
printk(KERN_WARNING "%s: discarding partial skb\n",
__func__);
return;
}
rlen = NLMSG_ALIGN(nlh->nlmsg_len);
if (rlen > skb->len)
rlen = skb->len;
if (nlh->nlmsg_type != SCSI_TRANSPORT_MSG) {
err = -EBADMSG;
goto next_msg;
}
hdr = NLMSG_DATA(nlh);
if ((hdr->version != SCSI_NL_VERSION) ||
(hdr->magic != SCSI_NL_MAGIC)) {
err = -EPROTOTYPE;
goto next_msg;
}
if (security_netlink_recv(skb, CAP_SYS_ADMIN)) {
err = -EPERM;
goto next_msg;
}
if (nlh->nlmsg_len < (sizeof(*nlh) + hdr->msglen)) {
printk(KERN_WARNING "%s: discarding partial message\n",
__func__);
goto next_msg;
}
/*
* Deliver message to the appropriate transport
*/
spin_lock_irqsave(&scsi_nl_lock, flags);
tport = hdr->transport;
if ((tport < SCSI_NL_MAX_TRANSPORTS) &&
!(transports[tport].flags & HANDLER_DELETING) &&
(transports[tport].msg_handler)) {
transports[tport].refcnt++;
spin_unlock_irqrestore(&scsi_nl_lock, flags);
err = transports[tport].msg_handler(skb);
spin_lock_irqsave(&scsi_nl_lock, flags);
transports[tport].refcnt--;
} else
err = -ENOENT;
spin_unlock_irqrestore(&scsi_nl_lock, flags);
next_msg:
if ((err) || (nlh->nlmsg_flags & NLM_F_ACK))
netlink_ack(skb, nlh, err);
skb_pull(skb, rlen);
}
}
/**
* scsi_nl_rcv_event - Event handler for a netlink socket.
* @this: event notifier block
* @event: event type
* @ptr: event payload
*
**/
static int
scsi_nl_rcv_event(struct notifier_block *this, unsigned long event, void *ptr)
{
struct netlink_notify *n = ptr;
struct scsi_nl_drvr *driver;
unsigned long flags;
int tport;
if (n->protocol != NETLINK_SCSITRANSPORT)
return NOTIFY_DONE;
spin_lock_irqsave(&scsi_nl_lock, flags);
scsi_nl_state |= STATE_EHANDLER_BSY;
/*
* Pass event on to any transports that may be listening
*/
for (tport = 0; tport < SCSI_NL_MAX_TRANSPORTS; tport++) {
if (!(transports[tport].flags & HANDLER_DELETING) &&
(transports[tport].event_handler)) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
transports[tport].event_handler(this, event, ptr);
spin_lock_irqsave(&scsi_nl_lock, flags);
}
}
/*
* Pass event on to any drivers that may be listening
*/
list_for_each_entry(driver, &scsi_nl_drivers, next) {
if (!(driver->flags & HANDLER_DELETING) &&
(driver->devt_handler)) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
driver->devt_handler(this, event, ptr);
spin_lock_irqsave(&scsi_nl_lock, flags);
}
}
scsi_nl_state &= ~STATE_EHANDLER_BSY;
spin_unlock_irqrestore(&scsi_nl_lock, flags);
return NOTIFY_DONE;
}
static struct notifier_block scsi_netlink_notifier = {
.notifier_call = scsi_nl_rcv_event,
};
/*
* GENERIC SCSI transport receive and event handlers
*/
/**
* scsi_generic_msg_handler - receive message handler for GENERIC transport messages
* @skb: socket receive buffer
**/
static int
scsi_generic_msg_handler(struct sk_buff *skb)
{
struct nlmsghdr *nlh = nlmsg_hdr(skb);
struct scsi_nl_hdr *snlh = NLMSG_DATA(nlh);
struct scsi_nl_drvr *driver;
struct Scsi_Host *shost;
unsigned long flags;
int err = 0, match, pid;
pid = NETLINK_CREDS(skb)->pid;
switch (snlh->msgtype) {
case SCSI_NL_SHOST_VENDOR:
{
struct scsi_nl_host_vendor_msg *msg = NLMSG_DATA(nlh);
/* Locate the driver that corresponds to the message */
spin_lock_irqsave(&scsi_nl_lock, flags);
match = 0;
list_for_each_entry(driver, &scsi_nl_drivers, next) {
if (driver->vendor_id == msg->vendor_id) {
match = 1;
break;
}
}
if ((!match) || (!driver->dmsg_handler)) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
err = -ESRCH;
goto rcv_exit;
}
if (driver->flags & HANDLER_DELETING) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
err = -ESHUTDOWN;
goto rcv_exit;
}
driver->refcnt++;
spin_unlock_irqrestore(&scsi_nl_lock, flags);
/* if successful, scsi_host_lookup takes a shost reference */
shost = scsi_host_lookup(msg->host_no);
if (!shost) {
err = -ENODEV;
goto driver_exit;
}
/* is this host owned by the vendor ? */
if (shost->hostt != driver->hostt) {
err = -EINVAL;
goto vendormsg_put;
}
/* pass message on to the driver */
err = driver->dmsg_handler(shost, (void *)&msg[1],
msg->vmsg_datalen, pid);
vendormsg_put:
/* release reference by scsi_host_lookup */
scsi_host_put(shost);
driver_exit:
/* release our own reference on the registration object */
spin_lock_irqsave(&scsi_nl_lock, flags);
driver->refcnt--;
spin_unlock_irqrestore(&scsi_nl_lock, flags);
break;
}
default:
err = -EBADR;
break;
}
rcv_exit:
if (err)
printk(KERN_WARNING "%s: Msgtype %d failed - err %d\n",
__func__, snlh->msgtype, err);
return err;
}
/**
* scsi_nl_add_transport -
* Registers message and event handlers for a transport. Enables
* receipt of netlink messages and events to a transport.
*
* @tport: transport registering handlers
* @msg_handler: receive message handler callback
* @event_handler: receive event handler callback
**/
int
scsi_nl_add_transport(u8 tport,
int (*msg_handler)(struct sk_buff *),
void (*event_handler)(struct notifier_block *, unsigned long, void *))
{
unsigned long flags;
int err = 0;
if (tport >= SCSI_NL_MAX_TRANSPORTS)
return -EINVAL;
spin_lock_irqsave(&scsi_nl_lock, flags);
if (scsi_nl_state & STATE_EHANDLER_BSY) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
msleep(1);
spin_lock_irqsave(&scsi_nl_lock, flags);
}
if (transports[tport].msg_handler || transports[tport].event_handler) {
err = -EALREADY;
goto register_out;
}
transports[tport].msg_handler = msg_handler;
transports[tport].event_handler = event_handler;
transports[tport].flags = 0;
transports[tport].refcnt = 0;
register_out:
spin_unlock_irqrestore(&scsi_nl_lock, flags);
return err;
}
EXPORT_SYMBOL_GPL(scsi_nl_add_transport);
/**
* scsi_nl_remove_transport -
* Disable transport receiption of messages and events
*
* @tport: transport deregistering handlers
*
**/
void
scsi_nl_remove_transport(u8 tport)
{
unsigned long flags;
spin_lock_irqsave(&scsi_nl_lock, flags);
if (scsi_nl_state & STATE_EHANDLER_BSY) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
msleep(1);
spin_lock_irqsave(&scsi_nl_lock, flags);
}
if (tport < SCSI_NL_MAX_TRANSPORTS) {
transports[tport].flags |= HANDLER_DELETING;
while (transports[tport].refcnt != 0) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
schedule_timeout_uninterruptible(HZ/4);
spin_lock_irqsave(&scsi_nl_lock, flags);
}
transports[tport].msg_handler = NULL;
transports[tport].event_handler = NULL;
transports[tport].flags = 0;
}
spin_unlock_irqrestore(&scsi_nl_lock, flags);
return;
}
EXPORT_SYMBOL_GPL(scsi_nl_remove_transport);
/**
* scsi_nl_add_driver -
* A driver is registering its interfaces for SCSI netlink messages
*
* @vendor_id: A unique identification value for the driver.
* @hostt: address of the driver's host template. Used
* to verify an shost is bound to the driver
* @nlmsg_handler: receive message handler callback
* @nlevt_handler: receive event handler callback
*
* Returns:
* 0 on Success
* error result otherwise
**/
int
scsi_nl_add_driver(u64 vendor_id, struct scsi_host_template *hostt,
int (*nlmsg_handler)(struct Scsi_Host *shost, void *payload,
u32 len, u32 pid),
void (*nlevt_handler)(struct notifier_block *nb,
unsigned long event, void *notify_ptr))
{
struct scsi_nl_drvr *driver;
unsigned long flags;
driver = kzalloc(sizeof(*driver), GFP_KERNEL);
if (unlikely(!driver)) {
printk(KERN_ERR "%s: allocation failure\n", __func__);
return -ENOMEM;
}
driver->dmsg_handler = nlmsg_handler;
driver->devt_handler = nlevt_handler;
driver->hostt = hostt;
driver->vendor_id = vendor_id;
spin_lock_irqsave(&scsi_nl_lock, flags);
if (scsi_nl_state & STATE_EHANDLER_BSY) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
msleep(1);
spin_lock_irqsave(&scsi_nl_lock, flags);
}
list_add_tail(&driver->next, &scsi_nl_drivers);
spin_unlock_irqrestore(&scsi_nl_lock, flags);
return 0;
}
EXPORT_SYMBOL_GPL(scsi_nl_add_driver);
/**
* scsi_nl_remove_driver -
* An driver is unregistering with the SCSI netlink messages
*
* @vendor_id: The unique identification value for the driver.
**/
void
scsi_nl_remove_driver(u64 vendor_id)
{
struct scsi_nl_drvr *driver;
unsigned long flags;
spin_lock_irqsave(&scsi_nl_lock, flags);
if (scsi_nl_state & STATE_EHANDLER_BSY) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
msleep(1);
spin_lock_irqsave(&scsi_nl_lock, flags);
}
list_for_each_entry(driver, &scsi_nl_drivers, next) {
if (driver->vendor_id == vendor_id) {
driver->flags |= HANDLER_DELETING;
while (driver->refcnt != 0) {
spin_unlock_irqrestore(&scsi_nl_lock, flags);
schedule_timeout_uninterruptible(HZ/4);
spin_lock_irqsave(&scsi_nl_lock, flags);
}
list_del(&driver->next);
kfree(driver);
spin_unlock_irqrestore(&scsi_nl_lock, flags);
return;
}
}
spin_unlock_irqrestore(&scsi_nl_lock, flags);
printk(KERN_ERR "%s: removal of driver failed - vendor_id 0x%llx\n",
__func__, (unsigned long long)vendor_id);
return;
}
EXPORT_SYMBOL_GPL(scsi_nl_remove_driver);
/**
* scsi_netlink_init - Called by SCSI subsystem to intialize
* the SCSI transport netlink interface
*
**/
void
scsi_netlink_init(void)
{
int error;
INIT_LIST_HEAD(&scsi_nl_drivers);
error = netlink_register_notifier(&scsi_netlink_notifier);
if (error) {
printk(KERN_ERR "%s: register of event handler failed - %d\n",
__func__, error);
return;
}
scsi_nl_sock = netlink_kernel_create(&init_net, NETLINK_SCSITRANSPORT,
SCSI_NL_GRP_CNT, scsi_nl_rcv_msg, NULL,
THIS_MODULE);
if (!scsi_nl_sock) {
printk(KERN_ERR "%s: register of recieve handler failed\n",
__func__);
netlink_unregister_notifier(&scsi_netlink_notifier);
return;
}
/* Register the entry points for the generic SCSI transport */
error = scsi_nl_add_transport(SCSI_NL_TRANSPORT,
scsi_generic_msg_handler, NULL);
if (error)
printk(KERN_ERR "%s: register of GENERIC transport handler"
" failed - %d\n", __func__, error);
return;
}
/**
* scsi_netlink_exit - Called by SCSI subsystem to disable the SCSI transport netlink interface
*
**/
void
scsi_netlink_exit(void)
{
scsi_nl_remove_transport(SCSI_NL_TRANSPORT);
if (scsi_nl_sock) {
netlink_kernel_release(scsi_nl_sock);
netlink_unregister_notifier(&scsi_netlink_notifier);
}
return;
}
/*
* Exported Interfaces
*/
/**
* scsi_nl_send_transport_msg -
* Generic function to send a single message from a SCSI transport to
* a single process
*
* @pid: receiving pid
* @hdr: message payload
*
**/
void
scsi_nl_send_transport_msg(u32 pid, struct scsi_nl_hdr *hdr)
{
struct sk_buff *skb;
struct nlmsghdr *nlh;
const char *fn;
char *datab;
u32 len, skblen;
int err;
if (!scsi_nl_sock) {
err = -ENOENT;
fn = "netlink socket";
goto msg_fail;
}
len = NLMSG_SPACE(hdr->msglen);
skblen = NLMSG_SPACE(len);
skb = alloc_skb(skblen, GFP_KERNEL);
if (!skb) {
err = -ENOBUFS;
fn = "alloc_skb";
goto msg_fail;
}
nlh = nlmsg_put(skb, pid, 0, SCSI_TRANSPORT_MSG, len - sizeof(*nlh), 0);
if (!nlh) {
err = -ENOBUFS;
fn = "nlmsg_put";
goto msg_fail_skb;
}
datab = NLMSG_DATA(nlh);
memcpy(datab, hdr, hdr->msglen);
err = nlmsg_unicast(scsi_nl_sock, skb, pid);
if (err < 0) {
fn = "nlmsg_unicast";
/* nlmsg_unicast already kfree_skb'd */
goto msg_fail;
}
return;
msg_fail_skb:
kfree_skb(skb);
msg_fail:
printk(KERN_WARNING
"%s: Dropped Message : pid %d Transport %d, msgtype x%x, "
"msglen %d: %s : err %d\n",
__func__, pid, hdr->transport, hdr->msgtype, hdr->msglen,
fn, err);
return;
}
EXPORT_SYMBOL_GPL(scsi_nl_send_transport_msg);
/**
* scsi_nl_send_vendor_msg - called to send a shost vendor unique message
* to a specific process id.
*
* @pid: process id of the receiver
* @host_no: host # sending the message
* @vendor_id: unique identifier for the driver's vendor
* @data_len: amount, in bytes, of vendor unique payload data
* @data_buf: pointer to vendor unique data buffer
*
* Returns:
* 0 on succesful return
* otherwise, failing error code
*
* Notes:
* This routine assumes no locks are held on entry.
*/
int
scsi_nl_send_vendor_msg(u32 pid, unsigned short host_no, u64 vendor_id,
char *data_buf, u32 data_len)
{
struct sk_buff *skb;
struct nlmsghdr *nlh;
struct scsi_nl_host_vendor_msg *msg;
u32 len, skblen;
int err;
if (!scsi_nl_sock) {
err = -ENOENT;
goto send_vendor_fail;
}
len = SCSI_NL_MSGALIGN(sizeof(*msg) + data_len);
skblen = NLMSG_SPACE(len);
skb = alloc_skb(skblen, GFP_KERNEL);
if (!skb) {
err = -ENOBUFS;
goto send_vendor_fail;
}
nlh = nlmsg_put(skb, 0, 0, SCSI_TRANSPORT_MSG,
skblen - sizeof(*nlh), 0);
if (!nlh) {
err = -ENOBUFS;
goto send_vendor_fail_skb;
}
msg = NLMSG_DATA(nlh);
INIT_SCSI_NL_HDR(&msg->snlh, SCSI_NL_TRANSPORT,
SCSI_NL_SHOST_VENDOR, len);
msg->vendor_id = vendor_id;
msg->host_no = host_no;
msg->vmsg_datalen = data_len; /* bytes */
memcpy(&msg[1], data_buf, data_len);
err = nlmsg_unicast(scsi_nl_sock, skb, pid);
if (err)
/* nlmsg_multicast already kfree_skb'd */
goto send_vendor_fail;
return 0;
send_vendor_fail_skb:
kfree_skb(skb);
send_vendor_fail:
printk(KERN_WARNING
"%s: Dropped SCSI Msg : host %d vendor_unique - err %d\n",
__func__, host_no, err);
return err;
}
EXPORT_SYMBOL(scsi_nl_send_vendor_msg);
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