From: Jeff Mahoney <jeffm@suse.com>
Subject: [PATCH] mISDN: Add support for group membership check
References: bnc#564423
Patch-mainline: Unsubmitted, needs upstream consensus

 This patch adds a module parameter to allow a group access to the
 mISDN devices. Otherwise, unpriviledged users on systems with ISDN hardware
 have the ability to dial out, potentially causing expensive bills.

Based on a different implementation by Patrick Koppen <isdn4linux@koppen.de>

Acked-by: Jeff Mahoney <jeffm@suse.com>
---

 drivers/isdn/mISDN/core.c   |    3 +++
 drivers/isdn/mISDN/core.h   |    1 +
 drivers/isdn/mISDN/socket.c |    8 ++++++++
 3 files changed, 12 insertions(+)

--- a/drivers/isdn/mISDN/core.c
+++ b/drivers/isdn/mISDN/core.c
@@ -21,10 +21,13 @@
 #include "core.h"
 
 static u_int debug;
+u_int misdn_permitted_gid;
 
 MODULE_AUTHOR("Karsten Keil");
 MODULE_LICENSE("GPL");
 module_param(debug, uint, S_IRUGO | S_IWUSR);
+module_param_named(gid, misdn_permitted_gid, uint, 0);
+MODULE_PARM_DESC(gid, "Unix group for accessing misdn socket (default 0)");
 
 static u64		device_ids;
 #define MAX_DEVICE_ID	63
--- a/drivers/isdn/mISDN/core.h
+++ b/drivers/isdn/mISDN/core.h
@@ -17,6 +17,7 @@
 
 extern struct mISDNdevice	*get_mdevice(u_int);
 extern int			get_mdevice_count(void);
+extern u_int misdn_permitted_gid;
 
 /* stack status flag */
 #define mISDN_STACK_ACTION_MASK		0x0000ffff
--- a/drivers/isdn/mISDN/socket.c
+++ b/drivers/isdn/mISDN/socket.c
@@ -608,6 +608,10 @@ data_sock_create(struct net *net, struct
 {
 	struct sock *sk;
 
+	if(!capable(CAP_SYS_ADMIN) && (misdn_permitted_gid != current_gid())
+		&& (!in_group_p(misdn_permitted_gid)))
+			return -EPERM;
+
 	if (sock->type != SOCK_DGRAM)
 		return -ESOCKTNOSUPPORT;
 
@@ -690,6 +694,10 @@ base_sock_ioctl(struct socket *sock, uns
 	case IMSETDEVNAME:
 		{
 			struct mISDN_devrename dn;
+			if(!capable(CAP_SYS_ADMIN)
+				&& (misdn_permitted_gid != current_gid())
+				&& (!in_group_p(misdn_permitted_gid)))
+					return -EPERM;
 			if (copy_from_user(&dn, (void __user *)arg,
 			    sizeof(dn))) {
 				err = -EFAULT;
