Add basic zfs ioc input nvpair validation

We want newer versions of libzfs_core to run against an existing
zfs kernel module (i.e. a deferred reboot or module reload after
an update).

Programmatically document, via a zfs_ioc_key_t, the valid arguments 
for the ioc commands that rely on nvpair input arguments (i.e. non 
legacy commands from libzfs_core). Automatically verify the expected 
pairs before dispatching a command.

This initial phase focuses on the non-legacy ioctls. A follow-on 
change can address the legacy ioctl input from the zfs_cmd_t.

The zfs_ioc_key_t for zfs_keys_channel_program looks like:

static const zfs_ioc_key_t zfs_keys_channel_program[] = {
       {"program",     DATA_TYPE_STRING,               0},
       {"arg",         DATA_TYPE_UNKNOWN,              0},
       {"sync",        DATA_TYPE_BOOLEAN_VALUE,        ZK_OPTIONAL},
       {"instrlimit",  DATA_TYPE_UINT64,               ZK_OPTIONAL},
       {"memlimit",    DATA_TYPE_UINT64,               ZK_OPTIONAL},
};

Introduce four input errors to identify specific input failures
(in addition to generic argument value errors like EINVAL, ERANGE, 
EBADF, and E2BIG).

ZFS_ERR_IOC_CMD_UNAVAIL the ioctl number is not supported by kernel
ZFS_ERR_IOC_ARG_UNAVAIL an input argument is not supported by kernel
ZFS_ERR_IOC_ARG_REQUIRED a required input argument is missing
ZFS_ERR_IOC_ARG_BADTYPE an input argument has an invalid type

Reviewed-by: Matthew Ahrens <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Don Brady <[email protected]>
Closes #7780 

2 files changed, 85 insertions, 2 deletions

diff --git a/lib/libzfs/libzfs_util.c b/lib/libzfs/libzfs_util.c
index d18b582c6..440ed3bc0 100644
--- a/lib/libzfs/libzfs_util.c
+++ b/lib/libzfs/libzfs_util.c
@@ -22,7 +22,7 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2018, Joyent, Inc. All rights reserved.
- * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
  * Copyright 2016 Igor Kozhukhov <[email protected]>
  * Copyright (c) 2017 Datto Inc.
  */
@@ -227,6 +227,9 @@ libzfs_error_description(libzfs_handle_t *hdl)
 	case EZFS_NOTSUP:
 		return (dgettext(TEXT_DOMAIN, "operation not supported "
 		    "on this dataset"));
+	case EZFS_IOC_NOTSUPPORTED:
+		return (dgettext(TEXT_DOMAIN, "operation not supported by "
+		    "zfs kernel module"));
 	case EZFS_ACTIVE_SPARE:
 		return (dgettext(TEXT_DOMAIN, "pool has active shared spare "
 		    "device"));
@@ -445,6 +448,22 @@ zfs_standard_error_fmt(libzfs_handle_t *hdl, int error, const char *fmt, ...)
 	case EREMOTEIO:
 		zfs_verror(hdl, EZFS_ACTIVE_POOL, fmt, ap);
 		break;
+	case ZFS_ERR_IOC_CMD_UNAVAIL:
+		zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "the loaded zfs "
+		    "module does not support this operation. A reboot may "
+		    "be required to enable this operation."));
+		zfs_verror(hdl, EZFS_IOC_NOTSUPPORTED, fmt, ap);
+		break;
+	case ZFS_ERR_IOC_ARG_UNAVAIL:
+		zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "the loaded zfs "
+		    "module does not support an option for this operation. "
+		    "A reboot may be required to enable this option."));
+		zfs_verror(hdl, EZFS_IOC_NOTSUPPORTED, fmt, ap);
+		break;
+	case ZFS_ERR_IOC_ARG_REQUIRED:
+	case ZFS_ERR_IOC_ARG_BADTYPE:
+		zfs_verror(hdl, EZFS_IOC_NOTSUPPORTED, fmt, ap);
+		break;
 	default:
 		zfs_error_aux(hdl, strerror(error));
 		zfs_verror(hdl, EZFS_UNKNOWN, fmt, ap);
@@ -556,6 +575,22 @@ zpool_standard_error_fmt(libzfs_handle_t *hdl, int error, const char *fmt, ...)
 	case ZFS_ERR_VDEV_TOO_BIG:
 		zfs_verror(hdl, EZFS_VDEV_TOO_BIG, fmt, ap);
 		break;
+	case ZFS_ERR_IOC_CMD_UNAVAIL:
+		zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "the loaded zfs "
+		    "module does not support this operation. A reboot may "
+		    "be required to enable this operation."));
+		zfs_verror(hdl, EZFS_IOC_NOTSUPPORTED, fmt, ap);
+		break;
+	case ZFS_ERR_IOC_ARG_UNAVAIL:
+		zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "the loaded zfs "
+		    "module does not support an option for this operation. "
+		    "A reboot may be required to enable this option."));
+		zfs_verror(hdl, EZFS_IOC_NOTSUPPORTED, fmt, ap);
+		break;
+	case ZFS_ERR_IOC_ARG_REQUIRED:
+	case ZFS_ERR_IOC_ARG_BADTYPE:
+		zfs_verror(hdl, EZFS_IOC_NOTSUPPORTED, fmt, ap);
+		break;
 	default:
 		zfs_error_aux(hdl, strerror(error));
 		zfs_verror(hdl, EZFS_UNKNOWN, fmt, ap);
diff --git a/lib/libzfs_core/libzfs_core.c b/lib/libzfs_core/libzfs_core.c
index 3a0b02690..f24581db8 100644
--- a/lib/libzfs_core/libzfs_core.c
+++ b/lib/libzfs_core/libzfs_core.c
@@ -20,7 +20,7 @@
  */
 
 /*
- * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2017 Datto Inc.
  * Copyright 2017 RackTop Systems.
@@ -78,6 +78,9 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
+#ifdef ZFS_DEBUG
+#include <stdio.h>
+#endif
 #include <errno.h>
 #include <fcntl.h>
 #include <pthread.h>
@@ -91,6 +94,42 @@ static int g_fd = -1;
 static pthread_mutex_t g_lock = PTHREAD_MUTEX_INITIALIZER;
 static int g_refcount;
 
+#ifdef ZFS_DEBUG
+static zfs_ioc_t fail_ioc_cmd;
+static zfs_errno_t fail_ioc_err;
+
+static void
+libzfs_core_debug_ioc(void)
+{
+	/*
+	 * To test running newer user space binaries with kernel's
+	 * that don't yet support an ioctl or a new ioctl arg we
+	 * provide an override to intentionally fail an ioctl.
+	 *
+	 * USAGE:
+	 * The override variable, ZFS_IOC_TEST, is of the form "cmd:err"
+	 *
+	 * For example, to fail a ZFS_IOC_POOL_CHECKPOINT with a
+	 * ZFS_ERR_IOC_CMD_UNAVAIL, the string would be "0x5a4d:1029"
+	 *
+	 * $ sudo sh -c "ZFS_IOC_TEST=0x5a4d:1029 zpool checkpoint tank"
+	 * cannot checkpoint 'tank': the loaded zfs module does not support
+	 * this operation. A reboot may be required to enable this operation.
+	 */
+	if (fail_ioc_cmd == 0) {
+		char *ioc_test = getenv("ZFS_IOC_TEST");
+		unsigned int ioc_num = 0, ioc_err = 0;
+
+		if (ioc_test != NULL &&
+		    sscanf(ioc_test, "%i:%i", &ioc_num, &ioc_err) == 2 &&
+		    ioc_num < ZFS_IOC_LAST)  {
+			fail_ioc_cmd = ioc_num;
+			fail_ioc_err = ioc_err;
+		}
+	}
+}
+#endif
+
 int
 libzfs_core_init(void)
 {
@@ -103,6 +142,10 @@ libzfs_core_init(void)
 		}
 	}
 	g_refcount++;
+
+#ifdef ZFS_DEBUG
+	libzfs_core_debug_ioc();
+#endif
 	(void) pthread_mutex_unlock(&g_lock);
 	return (0);
 }
@@ -135,6 +178,11 @@ lzc_ioctl(zfs_ioc_t ioc, const char *name,
 	ASSERT3S(g_refcount, >, 0);
 	VERIFY3S(g_fd, !=, -1);
 
+#ifdef ZFS_DEBUG
+	if (ioc == fail_ioc_cmd)
+		return (fail_ioc_err);
+#endif
+
 	if (name != NULL)
 		(void) strlcpy(zc.zc_name, name, sizeof (zc.zc_name));