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Commit 2873d214 authored by Jeff Layton's avatar Jeff Layton Committed by J. Bruce Fields
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nfsd: add a usermodehelper upcall for NFSv4 client ID tracking 



Add a new client tracker upcall type that uses call_usermodehelper to
call out to a program. This seems to be the preferred method of
calling out to usermode these days for seldom-called upcalls. It's
simple and doesn't require a running daemon, so it should "just work"
as long as the binary is installed.

The client tracking exit operation is also changed to check for a
NULL pointer before running. The UMH upcall doesn't need to do anything
at module teardown time.

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent a0af710a

fs/nfsd/nfs4recover.c

+133 −1
Original line number Diff line number Diff line
@@ -927,6 +927,137 @@ static struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops = { 
	.grace_done	= nfsd4_cld_grace_done,

};



/* upcall via usermodehelper */

static char cltrack_prog[PATH_MAX] = "/sbin/nfsdcltrack";

module_param_string(cltrack_prog, cltrack_prog, sizeof(cltrack_prog),

			S_IRUGO|S_IWUSR);

MODULE_PARM_DESC(cltrack_prog, "Path to the nfsdcltrack upcall program");



static int

nfsd4_umh_cltrack_upcall(char *cmd, char *arg)

{

	char *envp[] = { NULL };

	char *argv[4];

	int ret;



	if (unlikely(!cltrack_prog[0])) {

		dprintk("%s: cltrack_prog is disabled\n", __func__);

		return -EACCES;

	}



	dprintk("%s: cmd: %s\n", __func__, cmd);

	dprintk("%s: arg: %s\n", __func__, arg ? arg : "(null)");



	argv[0] = (char *)cltrack_prog;

	argv[1] = cmd;

	argv[2] = arg;

	argv[3] = NULL;



	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);

	/*

	 * Disable the upcall mechanism if we're getting an ENOENT or EACCES

	 * error. The admin can re-enable it on the fly by using sysfs

	 * once the problem has been fixed.

	 */

	if (ret == -ENOENT || ret == -EACCES) {

		dprintk("NFSD: %s was not found or isn't executable (%d). "

			"Setting cltrack_prog to blank string!",

			cltrack_prog, ret);

		cltrack_prog[0] = '\0';

	}

	dprintk("%s: %s return value: %d\n", __func__, cltrack_prog, ret);



	return ret;

}



static char *

bin_to_hex_dup(const unsigned char *src, int srclen)

{

	int i;

	char *buf, *hex;



	/* +1 for terminating NULL */

	buf = kmalloc((srclen * 2) + 1, GFP_KERNEL);

	if (!buf)

		return buf;



	hex = buf;

	for (i = 0; i < srclen; i++) {

		sprintf(hex, "%2.2x", *src++);

		hex += 2;

	}

	return buf;

}



static int

nfsd4_umh_cltrack_init(struct net __attribute__((unused)) *net)

{

	return nfsd4_umh_cltrack_upcall("init", NULL);

}



static void

nfsd4_umh_cltrack_create(struct nfs4_client *clp)

{

	char *hexid;



	hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);

	if (!hexid) {

		dprintk("%s: can't allocate memory for upcall!\n", __func__);

		return;

	}

	nfsd4_umh_cltrack_upcall("create", hexid);

	kfree(hexid);

}



static void

nfsd4_umh_cltrack_remove(struct nfs4_client *clp)

{

	char *hexid;



	hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);

	if (!hexid) {

		dprintk("%s: can't allocate memory for upcall!\n", __func__);

		return;

	}

	nfsd4_umh_cltrack_upcall("remove", hexid);

	kfree(hexid);

}



static int

nfsd4_umh_cltrack_check(struct nfs4_client *clp)

{

	int ret;

	char *hexid;



	hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);

	if (!hexid) {

		dprintk("%s: can't allocate memory for upcall!\n", __func__);

		return -ENOMEM;

	}

	ret = nfsd4_umh_cltrack_upcall("check", hexid);

	kfree(hexid);

	return ret;

}



static void

nfsd4_umh_cltrack_grace_done(struct net __attribute__((unused)) *net,

				time_t boot_time)

{

	char timestr[22]; /* FIXME: better way to determine max size? */



	sprintf(timestr, "%ld", boot_time);

	nfsd4_umh_cltrack_upcall("gracedone", timestr);

}



static struct nfsd4_client_tracking_ops nfsd4_umh_tracking_ops = {

	.init		= nfsd4_umh_cltrack_init,

	.exit		= NULL,

	.create		= nfsd4_umh_cltrack_create,

	.remove		= nfsd4_umh_cltrack_remove,

	.check		= nfsd4_umh_cltrack_check,

	.grace_done	= nfsd4_umh_cltrack_grace_done,

};



int

nfsd4_client_tracking_init(struct net *net)

{
@@ -957,6 +1088,7 @@ void 
nfsd4_client_tracking_exit(struct net *net)

{

	if (client_tracking_ops) {

		if (client_tracking_ops->exit)

			client_tracking_ops->exit(net);

		client_tracking_ops = NULL;

	}