Subject: [PATCH] scsi_netlink: Remove dead and buggy code

From: [email-masked] (Eric W. Biederman)
Date: Fri, 07 Sep 2012 15:39:21 -0700

The scsi netlink code confuses the netlink port id with a process id,
going so far as to read NETLINK_CREDS(skb)->pid instead of the correct
NETLINK_CB(skb).pid.  Fortunately it does not matter because nothing
registers to respond to scsi netlink requests.

The only interesting use of the scsi_netlink interface is
fc_host_post_vendor_event which sends a netlink multicast message.

Since nothing registers to handle scsi netlink messages kill all of the
registration logic, while retaining the same error handling behavior
preserving the userspace visible behavior and removing all of the
confused code that thought a netlink port id was a process id.

This was tested with a kernel allyesconfig build which had no problems.

Cc: James Bottomley <[email-masked]>
Cc: James Smart <[email-masked]>
Signed-off-by: "Eric W. Biederman" <[email-masked]>
---
 drivers/scsi/scsi_netlink.c |  555 ++-----------------------------------------
 include/scsi/scsi_netlink.h |   24 --
 2 files changed, 15 insertions(+), 564 deletions(-)

diff --git a/drivers/scsi/scsi_netlink.c b/drivers/scsi/scsi_netlink.c
index 8818dd6..abd43a3 100644
--- a/drivers/scsi/scsi_netlink.c
+++ b/drivers/scsi/scsi_netlink.c
@@ -33,40 +33,6 @@
 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
@@ -81,7 +47,6 @@ scsi_nl_rcv_msg(struct sk_buff *skb)
 {
 	struct nlmsghdr *nlh;
 	struct scsi_nl_hdr *hdr;
-	unsigned long flags;
 	u32 rlen;
 	int err, tport;
 
@@ -126,22 +91,24 @@ scsi_nl_rcv_msg(struct sk_buff *skb)
 		/*
 		 * 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
+		if (tport == SCSI_NL_TRANSPORT) {
+			switch (hdr->msgtype) {
+			case SCSI_NL_SHOST_VENDOR:
+				/* Locate the driver that corresponds to the message */
+				err = -ESRCH;
+				break;
+			default:
+				err = -EBADR;
+				break;
+			}
+			if (err)
+				printk(KERN_WARNING "%s: Msgtype %d failed - err %d\n",
+				       __func__, hdr->msgtype, err);
+		}
+		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);
@@ -150,333 +117,6 @@ next_msg:
 	}
 }
 
-
-/**
- * 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 initialize
  * 	the SCSI transport netlink interface
@@ -485,36 +125,19 @@ EXPORT_SYMBOL_GPL(scsi_nl_remove_driver);
 void
 scsi_netlink_init(void)
 {
-	int error;
 	struct netlink_kernel_cfg cfg = {
 		.input	= scsi_nl_rcv_msg,
 		.groups	= SCSI_NL_GRP_CNT,
 	};
 
-	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,
 					     THIS_MODULE, &cfg);
 	if (!scsi_nl_sock) {
 		printk(KERN_ERR "%s: register of receive 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;
 }
 
@@ -526,158 +149,10 @@ scsi_netlink_init(void)
 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 successful 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);
-
-
diff --git a/include/scsi/scsi_netlink.h b/include/scsi/scsi_netlink.h
index 5cb20cc..62b4eda 100644
--- a/include/scsi/scsi_netlink.h
+++ b/include/scsi/scsi_netlink.h
@@ -119,29 +119,5 @@ struct scsi_nl_host_vendor_msg {
 	(hdr)->msglen = mlen;					\
 	}
 
-
-#ifdef __KERNEL__
-
-#include <scsi/scsi_host.h>
-
-/* Exported Kernel Interfaces */
-int scsi_nl_add_transport(u8 tport,
-	 int (*msg_handler)(struct sk_buff *),
-	void (*event_handler)(struct notifier_block *, unsigned long, void *));
-void scsi_nl_remove_transport(u8 tport);
-
-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));
-void scsi_nl_remove_driver(u64 vendor_id);
-
-void scsi_nl_send_transport_msg(u32 pid, struct scsi_nl_hdr *hdr);
-int scsi_nl_send_vendor_msg(u32 pid, unsigned short host_no, u64 vendor_id,
-			 char *data_buf, u32 data_len);
-
-#endif /* __KERNEL__ */
-
 #endif /* SCSI_NETLINK_H */
 
-- 
1.7.5.4