linux: add sysctl to pass untranslated interface names

Reviewed by:	kib
MFC after:	2 weeks
Differential Revision: https://reviews.freebsd.org/D33792

sys/compat/linprocfs/linprocfs.c

@@ -1412,11 +1412,6 @@ linprocfs_doprocmem(PFS_FILL_ARGS)
 	return (error);
 }
 
-/*
- * Criteria for interface name translation
- */
-#define IFP_IS_ETH(ifp) (ifp->if_type == IFT_ETHER)
-
 static int
 linux_ifname(struct ifnet *ifp, char *buffer, size_t buflen)
 {
@@ -1426,7 +1421,7 @@ linux_ifname(struct ifnet *ifp, char *buffer, size_t buflen)
 	IFNET_RLOCK_ASSERT();
 
 	/* Short-circuit non ethernet interfaces */
-	if (!IFP_IS_ETH(ifp))
+	if (linux_use_real_ifname(ifp))
 		return (strlcpy(buffer, ifp->if_xname, buflen));
 
 	/* Determine the (relative) unit number for ethernet interfaces */
@@ -1434,7 +1429,7 @@ linux_ifname(struct ifnet *ifp, char *buffer, size_t buflen)
 	CK_STAILQ_FOREACH(ifscan, &V_ifnet, if_link) {
 		if (ifscan == ifp)
 			return (snprintf(buffer, buflen, "eth%d", ethno));
-		if (IFP_IS_ETH(ifscan))
+		if (!linux_use_real_ifname(ifscan))
 			ethno++;
 	}
 

sys/compat/linux/linux.h

@@ -55,12 +55,6 @@
 #define	LINUX_IFHWADDRLEN	6
 #define	LINUX_IFNAMSIZ		16
 
-/*
- * Criteria for interface name translation
- */
-#define	IFP_IS_ETH(ifp)		(ifp->if_type == IFT_ETHER)
-#define	IFP_IS_LOOP(ifp)	(ifp->if_type == IFT_LOOP)
-
 struct l_sockaddr {
 	unsigned short	sa_family;
 	char		sa_data[14];

sys/compat/linux/linux_ioctl.c

@@ -2121,7 +2121,7 @@ linux_ioctl_ifname(struct thread *td, struct l_ifreq *uifr)
 	error = ENODEV;
 	CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
 		if (ifr.ifr_ifindex == index) {
-			if (IFP_IS_ETH(ifp))
+			if (!linux_use_real_ifname(ifp))
 				snprintf(ifr.ifr_name, LINUX_IFNAMSIZ,
 				    "eth%d", ethno);
 			else
@@ -2130,7 +2130,7 @@ linux_ioctl_ifname(struct thread *td, struct l_ifreq *uifr)
 			error = 0;
 			break;
 		}
-		if (IFP_IS_ETH(ifp))
+		if (!linux_use_real_ifname(ifp))
 			ethno++;
 		index++;
 	}

sys/compat/linux/linux_util.c

@@ -50,6 +50,10 @@ __FBSDID("$FreeBSD$");
 #include <sys/systm.h>
 #include <sys/vnode.h>
 
+#include <net/if.h>
+#include <net/if_var.h>
+#include <net/if_types.h>
+
 #include <machine/stdarg.h>
 
 #include <compat/linux/linux_dtrace.h>
@@ -82,6 +86,11 @@ SYSCTL_STRING(_compat_linux, OID_AUTO, emul_path, CTLFLAG_RWTUN,
     linux_emul_path, sizeof(linux_emul_path),
     "Linux runtime environment path");
 
+static bool use_real_ifnames = false;
+SYSCTL_BOOL(_compat_linux, OID_AUTO, use_real_ifnames, CTLFLAG_RWTUN,
+    &use_real_ifnames, 0,
+    "Use FreeBSD interface names instead of generating ethN aliases");
+
 /*
  * Search an alternate path before passing pathname arguments on to
  * system calls. Useful for keeping a separate 'emulation tree'.
@@ -315,3 +324,9 @@ linux_device_unregister_handler(struct linux_device_handler *d)
 
 	return (EINVAL);
 }
+
+bool
+linux_use_real_ifname(const struct ifnet *ifp)
+{
+	return (use_real_ifnames || !IFP_IS_ETH(ifp));
+}

sys/compat/linux/linux_util.h

@@ -120,6 +120,15 @@ int	linux_vn_get_major_minor(const struct vnode *vn, int *major, int *minor);
 char	*linux_get_char_devices(void);
 void	linux_free_get_char_devices(char *string);
 
+/*
+ * Criteria for interface name translation
+ */
+#define	IFP_IS_ETH(ifp)		((ifp)->if_type == IFT_ETHER)
+#define	IFP_IS_LOOP(ifp)	((ifp)->if_type == IFT_LOOP)
+
+struct ifnet;
+bool	linux_use_real_ifname(const struct ifnet *ifp);
+
 #if defined(KTR)
 
 #define	KTR_LINUX				KTR_SUBSYS

sys/modules/linux_common/Makefile

@@ -11,6 +11,7 @@ EXPORT_SYMS=
 EXPORT_SYMS+=	linux_emul_path
 EXPORT_SYMS+=	linux_get_osname
 EXPORT_SYMS+=	linux_get_osrelease
+EXPORT_SYMS+=	linux_use_real_ifname
 
 .if !defined(KERNBUILDDIR)
 .warning Building Linuxulator outside of a kernel does not make sense