ZFS expects a copyout of zfs_cmd_t on an ioctl error. Our sys_ioctl()

doesn't copyout in this case.

To solve this issue a new struct zfs_iocparm_t is introduced consisting of:
- zfs_ioctl_version (future backwards compatibility purposes)
- user space pointer to zfs_cmd_t (copyin and copyout)
- size of zfs_cmd_t (verification purposes)

The copyin and copyout of zfs_cmd_t is now done the illumos (vendor) way
what makes porting of new changes easier and ensures correct behavior if
returning an error.

MFC after:	10 days

2 files changed, 19 insertions, 5 deletions

diff --git a/sys/cddl/contrib/opensolaris/common/zfs/zfs_ioctl_compat.c b/sys/cddl/contrib/opensolaris/common/zfs/zfs_ioctl_compat.c
index df91b2e..cfa4f44 100644
--- a/sys/cddl/contrib/opensolaris/common/zfs/zfs_ioctl_compat.c
+++ b/sys/cddl/contrib/opensolaris/common/zfs/zfs_ioctl_compat.c
@@ -577,12 +577,18 @@ zcmd_ioctl_compat(int fd, int request, zfs_cmd_t *zc, const int cflag)
 	int nc, ret;
 	void *zc_c;
 	unsigned long ncmd;
+	zfs_iocparm_t zp;
 
 	switch (cflag) {
 	case ZFS_CMD_COMPAT_NONE:
+		ncmd = _IOWR('Z', request, struct zfs_iocparm);
+		zp.zfs_cmd = (uint64_t)zc;
+		zp.zfs_cmd_size = sizeof(zfs_cmd_t);
+		zp.zfs_ioctl_version = ZFS_IOCVER_CURRENT;
+		return (ioctl(fd, ncmd, &zp));
+	case ZFS_CMD_COMPAT_LZC:
 		ncmd = _IOWR('Z', request, struct zfs_cmd);
-		ret = ioctl(fd, ncmd, zc);
-		return (ret);
+		return (ioctl(fd, ncmd, zc));
 	case ZFS_CMD_COMPAT_DEADMAN:
 		zc_c = malloc(sizeof(zfs_cmd_deadman_t));
 		ncmd = _IOWR('Z', request, struct zfs_cmd_deadman);
@@ -677,7 +683,7 @@ zfs_ioctl_compat_innvl(zfs_cmd_t *zc, nvlist_t * innvl, const int vec,
 	char *poolname, *snapname;
 	int err;
 
-	if (cflag == ZFS_CMD_COMPAT_NONE)
+	if (cflag == ZFS_CMD_COMPAT_NONE || cflag == ZFS_CMD_COMPAT_LZC)
 		goto out;
 
 	switch (vec) {
@@ -828,7 +834,7 @@ zfs_ioctl_compat_outnvl(zfs_cmd_t *zc, nvlist_t * outnvl, const int vec,
 {
 	nvlist_t *tmpnvl;
 
-	if (cflag == ZFS_CMD_COMPAT_NONE)
+	if (cflag == ZFS_CMD_COMPAT_NONE || cflag == ZFS_CMD_COMPAT_LZC)
 		return (outnvl);
 
 	switch (vec) {
diff --git a/sys/cddl/contrib/opensolaris/common/zfs/zfs_ioctl_compat.h b/sys/cddl/contrib/opensolaris/common/zfs/zfs_ioctl_compat.h
index 0e7130d..6e8d51d 100644
--- a/sys/cddl/contrib/opensolaris/common/zfs/zfs_ioctl_compat.h
+++ b/sys/cddl/contrib/opensolaris/common/zfs/zfs_ioctl_compat.h
@@ -49,19 +49,27 @@ extern "C" {
 #define	ZFS_IOCVER_NONE		0
 #define	ZFS_IOCVER_DEADMAN	1
 #define	ZFS_IOCVER_LZC		2
-#define	ZFS_IOCVER_CURRENT	ZFS_IOCVER_LZC
+#define	ZFS_IOCVER_ZCMD		3
+#define	ZFS_IOCVER_CURRENT	ZFS_IOCVER_ZCMD
 
 /* compatibility conversion flag */
 #define	ZFS_CMD_COMPAT_NONE	0
 #define	ZFS_CMD_COMPAT_V15	1
 #define	ZFS_CMD_COMPAT_V28	2
 #define	ZFS_CMD_COMPAT_DEADMAN	3
+#define	ZFS_CMD_COMPAT_LZC	4
 
 #define	ZFS_IOC_COMPAT_PASS	254
 #define	ZFS_IOC_COMPAT_FAIL	255
 
 #define	ZFS_IOCREQ(ioreq)	((ioreq) & 0xff)
 
+typedef struct zfs_iocparm {
+	uint32_t	zfs_ioctl_version;
+	uint64_t	zfs_cmd;
+	uint64_t	zfs_cmd_size;
+} zfs_iocparm_t;
+
 typedef struct zinject_record_v15 {
 	uint64_t	zi_objset;
 	uint64_t	zi_object;