Add basic credential support and splat tests.

The previous credential implementation simply provided the needed types and
a couple of dummy functions needed.  This update correctly ties the basic
Solaris credential API in to one of two Linux kernel APIs.

Prior to 2.6.29 the linux kernel embeded all credentials in the task
structure.  For these kernels, we pass around the entire task struct as if
it were the credential, then we use the helper functions to extract the
credential related bits.

As of 2.6.29 a new credential type was added which we can and do fairly
cleanly layer on top of.  Once again the helper functions nicely hide
the implementation details from all callers.

Three tests were added to the splat test framework to verify basic
correctness.  They should be extended as needed when need credential
functions are added.

13 files changed, 839 insertions, 56 deletions

diff --git a/config/spl-build.m4 b/config/spl-build.m4
index 35cc8e401..79fcd2548 100644
--- a/config/spl-build.m4
+++ b/config/spl-build.m4
@@ -64,6 +64,8 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
 	SPL_AC_ZONE_STAT_ITEM_FIA
 	SPL_AC_2ARGS_VFS_UNLINK
 	SPL_AC_4ARGS_VFS_RENAME
+	SPL_AC_CRED_STRUCT
+	SPL_AC_GROUPS_SEARCH
 ])
 
 AC_DEFUN([SPL_AC_MODULE_SYMVERS], [
@@ -1099,3 +1101,34 @@ AC_DEFUN([SPL_AC_4ARGS_VFS_RENAME],
 		AC_MSG_RESULT(no)
 	])
 ])
+
+dnl #
+dnl # 2.6.29 API change,
+dnl # check whether 'struct cred' exists
+dnl #
+AC_DEFUN([SPL_AC_CRED_STRUCT], [
+	AC_MSG_CHECKING([whether struct cred exists])
+	SPL_LINUX_TRY_COMPILE([
+		#include <linux/cred.h>
+	],[
+		struct cred *cr;
+		cr  = NULL;
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_CRED_STRUCT, 1, [struct cred exists])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
+dnl # Custom SPL patch may export this symbol
+dnl #
+AC_DEFUN([SPL_AC_GROUPS_SEARCH], [
+	SPL_CHECK_SYMBOL_EXPORT(
+		[groups_search],
+		[],
+		[AC_DEFINE(HAVE_GROUPS_SEARCH, 1,
+		[groups_search() is available])],
+		[])
+])
diff --git a/configure b/configure
index 5e3358490..a342d73a2 100755
--- a/configure
+++ b/configure
@@ -21342,6 +21342,113 @@ fi
 
 
 
+
+	echo "$as_me:$LINENO: checking whether struct cred exists" >&5
+echo $ECHO_N "checking whether struct cred exists... $ECHO_C" >&6
+
+
+cat >conftest.c <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+
+		#include <linux/cred.h>
+
+int
+main (void)
+{
+
+		struct cred *cr;
+		cr  = NULL;
+
+  ;
+  return 0;
+}
+
+_ACEOF
+
+
+	rm -Rf build && mkdir -p build
+	echo "obj-m := conftest.o" >build/Makefile
+	if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+		echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_CRED_STRUCT 1
+_ACEOF
+
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+		echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+
+
+fi
+
+	rm -Rf build
+
+
+
+
+	echo "$as_me:$LINENO: checking whether symbol groups_search is exported" >&5
+echo $ECHO_N "checking whether symbol groups_search is exported... $ECHO_C" >&6
+	grep -q -E '[[:space:]]groups_search[[:space:]]' \
+		$LINUX_OBJ/Module*.symvers 2>/dev/null
+	rc=$?
+	if test $rc -ne 0; then
+		export=0
+		for file in ; do
+			grep -q -E "EXPORT_SYMBOL.*(groups_search)" \
+				"$LINUX_OBJ/$file" 2>/dev/null
+			rc=$?
+		        if test $rc -eq 0; then
+		                export=1
+		                break;
+		        fi
+		done
+		if test $export -eq 0; then
+			echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+		else
+			echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_GROUPS_SEARCH 1
+_ACEOF
+
+		fi
+	else
+		echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_GROUPS_SEARCH 1
+_ACEOF
+
+	fi
+
+
  ;;
                 user)      ;;
                 all)
@@ -23736,6 +23843,113 @@ fi
 
 
 
+	echo "$as_me:$LINENO: checking whether struct cred exists" >&5
+echo $ECHO_N "checking whether struct cred exists... $ECHO_C" >&6
+
+
+cat >conftest.c <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+
+		#include <linux/cred.h>
+
+int
+main (void)
+{
+
+		struct cred *cr;
+		cr  = NULL;
+
+  ;
+  return 0;
+}
+
+_ACEOF
+
+
+	rm -Rf build && mkdir -p build
+	echo "obj-m := conftest.o" >build/Makefile
+	if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+		echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_CRED_STRUCT 1
+_ACEOF
+
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+		echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+
+
+fi
+
+	rm -Rf build
+
+
+
+
+	echo "$as_me:$LINENO: checking whether symbol groups_search is exported" >&5
+echo $ECHO_N "checking whether symbol groups_search is exported... $ECHO_C" >&6
+	grep -q -E '[[:space:]]groups_search[[:space:]]' \
+		$LINUX_OBJ/Module*.symvers 2>/dev/null
+	rc=$?
+	if test $rc -ne 0; then
+		export=0
+		for file in ; do
+			grep -q -E "EXPORT_SYMBOL.*(groups_search)" \
+				"$LINUX_OBJ/$file" 2>/dev/null
+			rc=$?
+		        if test $rc -eq 0; then
+		                export=1
+		                break;
+		        fi
+		done
+		if test $export -eq 0; then
+			echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+		else
+			echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_GROUPS_SEARCH 1
+_ACEOF
+
+		fi
+	else
+		echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_GROUPS_SEARCH 1
+_ACEOF
+
+	fi
+
+
+
                            ;;
                 *)
                 echo "$as_me:$LINENO: result: Error!" >&5
diff --git a/include/splat-ctl.h b/include/splat-ctl.h
index 7f49b9fff..fc68395e8 100644
--- a/include/splat-ctl.h
+++ b/include/splat-ctl.h
@@ -105,6 +105,7 @@ typedef struct splat_cmd {
 #define SPLAT_SUBSYSTEM_ATOMIC		0x0b00
 #define SPLAT_SUBSYSTEM_LIST		0x0c00
 #define SPLAT_SUBSYSTEM_GENERIC		0x0d00
+#define SPLAT_SUBSYSTEM_CRED		0x0e00
 #define SPLAT_SUBSYSTEM_UNKNOWN		0xff00
 
 #endif /* _SPLAT_CTL_H */
diff --git a/include/sys/cred.h b/include/sys/cred.h
index 47eeda2cb..9717b66bc 100644
--- a/include/sys/cred.h
+++ b/include/sys/cred.h
@@ -9,69 +9,33 @@ extern "C" {
 #include <sys/types.h>
 #include <sys/vfs.h>
 
-/* XXX - Portions commented out because we really just want to have the type
- * defined and the contents aren't nearly so important at the moment. */
-typedef struct cred {
-        uint_t          cr_ref;         /* reference count */
-        uid_t           cr_uid;         /* effective user id */
-        gid_t           cr_gid;         /* effective group id */
-        uid_t           cr_ruid;        /* real user id */
-        gid_t           cr_rgid;        /* real group id */
-        uid_t           cr_suid;        /* "saved" user id (from exec) */
-        gid_t           cr_sgid;        /* "saved" group id (from exec) */
-        uint_t          cr_ngroups;     /* number of groups returned by */
-                                        /* crgroups() */
-#if 0
-        cred_priv_t     cr_priv;        /* privileges */
-        projid_t        cr_projid;      /* project */
-        struct zone     *cr_zone;       /* pointer to per-zone structure */
-        struct ts_label_s *cr_label;    /* pointer to the effective label */
-        credsid_t       *cr_ksid;       /* pointer to SIDs */
-#endif
-        gid_t           cr_groups[1];   /* cr_groups size not fixed */
-                                        /* audit info is defined dynamically */
-                                        /* and valid only when audit enabled */
-        /* auditinfo_addr_t     cr_auinfo;      audit info */
-} cred_t;
+#ifdef HAVE_CRED_STRUCT
 
-#define kcred				NULL
-#define CRED()				NULL
+typedef struct cred cred_t;
 
-static __inline__ uid_t
-crgetuid(cred_t *cr)
-{
-	return 0;
-}
+#define kcred		((cred_t *)(init_task.cred))
+#define CRED()		((cred_t *)current_cred())
 
-static __inline__ gid_t
-crgetgid(cred_t *cr)
-{
-	return 0;
-}
+#else
 
-static __inline__ int
-crgetngroups(cred_t *cr)
-{
-	return 0;
-}
+typedef struct task_struct cred_t;
 
-static __inline__ gid_t *
-crgetgroups(cred_t *cr)
-{
-	return NULL;
-}
-
-static __inline__ int
-groupmember(gid_t gid, const cred_t *cr)
-{
-	/* Primary group check */
-	if ((cr) && (gid == cr->cr_gid))
-		return 1;
+#define kcred		((cred_t *)&init_task)
+#define CRED()		((cred_t *)current)
 
-	/* Supplemental group check (unsupported) */
-	return 0;
-}
+#endif /* HAVE_CRED_STRUCT */
 
+extern void crhold(cred_t *cr);
+extern void crfree(cred_t *cr);
+extern uid_t crgetuid(const cred_t *cr);
+extern uid_t crgetruid(const cred_t *cr);
+extern uid_t crgetsuid(const cred_t *cr);
+extern gid_t crgetgid(const cred_t *cr);
+extern gid_t crgetrgid(const cred_t *cr);
+extern gid_t crgetsgid(const cred_t *cr);
+extern int crgetngroups(const cred_t *cr);
+extern gid_t * crgetgroups(const cred_t *cr);
+extern int groupmember(gid_t gid, const cred_t *cr);
 
 #ifdef  __cplusplus
 }
diff --git a/include/sys/debug.h b/include/sys/debug.h
index f19231b90..8da76863c 100644
--- a/include/sys/debug.h
+++ b/include/sys/debug.h
@@ -53,6 +53,7 @@ extern unsigned long spl_debug_subsys;
 #define S_GENERIC     0x00002000
 #define S_PROC        0x00004000
 #define S_MODULE      0x00008000
+#define S_CRED        0x00010000
 
 #define D_TRACE       0x00000001
 #define D_INFO        0x00000002
diff --git a/module/spl/Makefile.in b/module/spl/Makefile.in
index e9c8d3470..ad29af406 100644
--- a/module/spl/Makefile.in
+++ b/module/spl/Makefile.in
@@ -23,3 +23,4 @@ spl-objs += spl-mutex.o
 spl-objs += spl-kstat.o
 spl-objs += spl-condvar.o
 spl-objs += spl-xdr.o
+spl-objs += spl-cred.o
diff --git a/module/spl/spl-cred.c b/module/spl/spl-cred.c
new file mode 100644
index 000000000..c5994aa20
--- /dev/null
+++ b/module/spl/spl-cred.c
@@ -0,0 +1,308 @@
+/*
+ *  This file is part of the SPL: Solaris Porting Layer.
+ *
+ *  Copyright (c) 2009 Lawrence Livermore National Security, LLC.
+ *  Produced at Lawrence Livermore National Laboratory
+ *  Written by:
+ *          Brian Behlendorf <[email protected]>,
+ *  UCRL-CODE-235197
+ *
+ *  This is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA.
+ */
+
+#include <sys/cred.h>
+
+#ifdef DEBUG_SUBSYSTEM
+#undef DEBUG_SUBSYSTEM
+#endif
+
+#define DEBUG_SUBSYSTEM S_CRED
+
+#ifdef HAVE_GROUPS_SEARCH
+/* Symbol may be exported by custom kernel patch */
+#define cr_groups_search(gi, grp)	groups_search(gi, grp)
+#else
+/* Implementation from 2.6.30 kernel */
+static int
+cr_groups_search(const struct group_info *group_info, gid_t grp)
+{
+	unsigned int left, right;
+
+	if (!group_info)
+		return 0;
+
+	left = 0;
+	right = group_info->ngroups;
+	while (left < right) {
+		unsigned int mid = (left+right)/2;
+		int cmp = grp - GROUP_AT(group_info, mid);
+		if (cmp > 0)
+			left = mid + 1;
+		else if (cmp < 0)
+			right = mid;
+		else
+			return 1;
+	}
+	return 0;
+}
+#endif
+
+#ifdef HAVE_CRED_STRUCT
+
+/*
+ * As of 2.6.29 a clean credential API appears in the linux kernel.
+ * We attempt to layer the Solaris API on top of the linux API.
+ */
+
+/* Hold a reference on the credential and group info */
+void
+crhold(cred_t *cr)
+{
+	(void)get_cred((const cred_t *)cr);
+	(void)get_group_info(cr->group_info);
+}
+
+/* Free a reference on the credential and group info */
+void
+crfree(cred_t *cr)
+{
+	put_group_info(cr->group_info);
+	put_cred((const cred_t *)cr);
+}
+
+/* Return the effective user id */
+uid_t
+crgetuid(const cred_t *cr)
+{
+	return cr->euid;
+}
+
+/* Return the real user id */
+uid_t
+crgetruid(const cred_t *cr)
+{
+	return cr->uid;
+}
+
+/* Return the saved user id */
+uid_t
+crgetsuid(const cred_t *cr)
+{
+	return cr->suid;
+}
+
+/* Return the effective group id */
+gid_t
+crgetgid(const cred_t *cr)
+{
+	return cr->egid;
+}
+
+/* Return the real group id */
+gid_t
+crgetrgid(const cred_t *cr)
+{
+	return cr->gid;
+}
+
+/* Return the saved group id */
+gid_t
+crgetsgid(const cred_t *cr)
+{
+	return cr->sgid;
+}
+
+/* Return the number of supplemental groups */
+int
+crgetngroups(const cred_t *cr)
+{
+	struct group_info *gi;
+	int rc;
+
+	gi = get_group_info(cr->group_info);
+	rc = gi->ngroups;
+	put_group_info(gi);
+
+	return rc;
+}
+
+/*
+ * Return an array of supplemental gids.  The returned address is safe
+ * to use as long as the caller has taken a reference with crhold().
+ * The caller is responsible for releasing the reference with crfree().
+ */
+gid_t *
+crgetgroups(const cred_t *cr)
+{
+	struct group_info *gi;
+	gid_t *gids;
+
+	gi = get_group_info(cr->group_info);
+	gids = gi->blocks[0];
+	put_group_info(gi);
+
+	return gids;
+}
+
+/* Check if the passed gid is available is in supplied credential. */
+int
+groupmember(gid_t gid, const cred_t *cr)
+{
+	struct group_info *gi;
+	int rc;
+
+	gi = get_group_info(cr->group_info);
+	rc = cr_groups_search(cr->group_info, gid);
+	put_group_info(gi);
+
+	return rc;
+}
+
+#else /* HAVE_CRED_STRUCT */
+
+/*
+ * Until very recently all credential information was embedded in
+ * the linux task struct.  For this reason to simulate a Solaris
+ * cred_t we need to pass the entire task structure around.
+ */
+
+/* Hold a reference on the credential and group info */
+void
+crhold(cred_t *cr)
+{
+	get_task_struct(cr);
+}
+
+/* Free a reference on the credential and group info */
+void
+crfree(cred_t *cr)
+{
+	put_task_struct(cr);
+}
+
+/* Return the effective user id */
+uid_t
+crgetuid(const cred_t *cr) {
+	return cr->euid;
+}
+
+/* Return the effective real id */
+uid_t
+crgetruid(const cred_t *cr) {
+	return cr->uid;
+}
+
+/* Return the effective saved id */
+uid_t
+crgetsuid(const cred_t *cr) {
+	return cr->suid;
+}
+
+/* Return the effective group id */
+gid_t
+crgetgid(const cred_t *cr) {
+	return cr->egid;
+}
+
+/* Return the real group id */
+gid_t
+crgetrgid(const cred_t *cr) {
+	return cr->gid;
+}
+
+/* Return the saved group id */
+gid_t
+crgetsgid(const cred_t *cr) {
+	return cr->sgid;
+}
+
+/* Return the number of supplemental groups */
+int
+crgetngroups(const cred_t *cr)
+{
+	int lock, rc;
+
+	lock = (cr != current);
+	if (lock)
+		task_lock((struct task_struct *)cr);
+
+	get_group_info(cr->group_info);
+	rc = cr->group_info->ngroups;
+	put_group_info(cr->group_info);
+
+	if (lock)
+		task_unlock((struct task_struct *)cr);
+
+	return rc;
+}
+
+/*
+ * Return an array of supplemental gids.  The returned address is safe
+ * to use as long as the caller has taken a reference with crhold().
+ * The caller is responsible for releasing the reference with crfree().
+ */
+gid_t *
+crgetgroups(const cred_t *cr)
+{
+	gid_t *gids;
+	int lock;
+
+	lock = (cr != current);
+	if (lock)
+		task_lock((struct task_struct *)cr);
+
+	get_group_info(cr->group_info);
+	gids = cr->group_info->blocks[0];
+	put_group_info(cr->group_info);
+
+	if (lock)
+		task_unlock((struct task_struct *)cr);
+
+	return gids;
+}
+
+/* Check if the passed gid is available is in supplied credential. */
+int
+groupmember(gid_t gid, const cred_t *cr)
+{
+	int lock, rc;
+
+	lock = (cr != current);
+	if (lock)
+		task_lock((struct task_struct *)cr);
+
+	get_group_info(cr->group_info);
+	rc = cr_groups_search(cr->group_info, gid);
+	put_group_info(cr->group_info);
+
+	if (lock)
+		task_unlock((struct task_struct *)cr);
+
+	return rc;
+}
+
+#endif /* HAVE_CRED_STRUCT */
+
+EXPORT_SYMBOL(crhold);
+EXPORT_SYMBOL(crfree);
+EXPORT_SYMBOL(crgetuid);
+EXPORT_SYMBOL(crgetruid);
+EXPORT_SYMBOL(crgetsuid);
+EXPORT_SYMBOL(crgetgid);
+EXPORT_SYMBOL(crgetrgid);
+EXPORT_SYMBOL(crgetsgid);
+EXPORT_SYMBOL(crgetngroups);
+EXPORT_SYMBOL(crgetgroups);
+EXPORT_SYMBOL(groupmember);
diff --git a/module/spl/spl-debug.c b/module/spl/spl-debug.c
index a60740519..6d71f4b82 100644
--- a/module/spl/spl-debug.c
+++ b/module/spl/spl-debug.c
@@ -157,6 +157,8 @@ spl_debug_subsys2str(int subsys)
                 return "proc";
         case S_MODULE:
                 return "module";
+	case S_CRED:
+                return "cred";
         }
 }
 
diff --git a/module/splat/Makefile.in b/module/splat/Makefile.in
index c2d4c3f22..2f63b458a 100644
--- a/module/splat/Makefile.in
+++ b/module/splat/Makefile.in
@@ -20,3 +20,4 @@ splat-objs += splat-kobj.o
 splat-objs += splat-atomic.o
 splat-objs += splat-list.o
 splat-objs += splat-generic.o
+splat-objs += splat-cred.o
diff --git a/module/splat/splat-cred.c b/module/splat/splat-cred.c
new file mode 100644
index 000000000..f808625e8
--- /dev/null
+++ b/module/splat/splat-cred.c
@@ -0,0 +1,247 @@
+/*
+ *  This file is part of the SPL: Solaris Porting Layer.
+ *
+ *  Copyright (c) 2009 Lawrence Livermore National Security, LLC.
+ *  Produced at Lawrence Livermore National Laboratory
+ *  Written by:
+ *          Brian Behlendorf <[email protected]>,
+ *  UCRL-CODE-235197
+ *
+ *  This is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA.
+ */
+
+#include "splat-internal.h"
+
+#define SPLAT_CRED_NAME			"cred"
+#define SPLAT_CRED_DESC			"Kernel Cred Tests"
+
+#define SPLAT_CRED_TEST1_ID		0x0e01
+#define SPLAT_CRED_TEST1_NAME		"cred"
+#define SPLAT_CRED_TEST1_DESC		"Task Credential Test"
+
+#define SPLAT_CRED_TEST2_ID		0x0e02
+#define SPLAT_CRED_TEST2_NAME		"kcred"
+#define SPLAT_CRED_TEST2_DESC		"Kernel Credential Test"
+
+#define SPLAT_CRED_TEST3_ID		0x0e03
+#define SPLAT_CRED_TEST3_NAME		"groupmember"
+#define SPLAT_CRED_TEST3_DESC		"Group Member Test"
+
+#define GROUP_STR_SIZE			128
+#define GROUP_STR_REDZONE		16
+
+static int
+splat_cred_test1(struct file *file, void *arg)
+{
+	char str[GROUP_STR_SIZE];
+	uid_t uid, ruid, suid;
+	gid_t gid, rgid, sgid, *groups;
+	int ngroups, i, count = 0;
+
+	uid  = crgetuid(CRED());
+	ruid = crgetruid(CRED());
+	suid = crgetsuid(CRED());
+
+	gid  = crgetgid(CRED());
+	rgid = crgetrgid(CRED());
+	sgid = crgetsgid(CRED());
+
+	crhold(CRED());
+	ngroups = crgetngroups(CRED());
+	groups  = crgetgroups(CRED());
+
+	memset(str, 0, GROUP_STR_SIZE);
+	for (i = 0; i < ngroups; i++) {
+		count += sprintf(str + count, "%d ", groups[i]);
+
+		if (count > (GROUP_STR_SIZE - GROUP_STR_REDZONE)) {
+			splat_vprint(file, SPLAT_CRED_TEST1_NAME,
+				     "Failed too many group entries for temp "
+				     "buffer: %d, %s\n", ngroups, str);
+			return -ENOSPC;
+		}
+	}
+
+	crfree(CRED());
+
+	splat_vprint(file, SPLAT_CRED_TEST1_NAME,
+		     "uid: %d ruid: %d suid: %d "
+		     "gid: %d rgid: %d sgid: %d\n",
+		     uid, ruid, suid, gid, rgid, sgid);
+	splat_vprint(file, SPLAT_CRED_TEST1_NAME,
+		     "ngroups: %d groups: %s\n", ngroups, str);
+
+	if (uid || ruid || suid || gid || rgid || sgid) {
+		splat_vprint(file, SPLAT_CRED_TEST1_NAME,
+			     "Failed expected all uids+gids to be %d\n", 0);
+		return -EIDRM;
+	}
+
+	if (ngroups > NGROUPS_MAX) {
+		splat_vprint(file, SPLAT_CRED_TEST1_NAME,
+			     "Failed ngroups must not exceed NGROUPS_MAX: "
+			     "%d > %d\n", ngroups, NGROUPS_MAX);
+		return -EIDRM;
+	}
+
+	splat_vprint(file, SPLAT_CRED_TEST1_NAME,
+		     "Success sane CRED(): %d\n", 0);
+
+        return 0;
+} /* splat_cred_test1() */
+
+static int
+splat_cred_test2(struct file *file, void *arg)
+{
+	char str[GROUP_STR_SIZE];
+	uid_t uid, ruid, suid;
+	gid_t gid, rgid, sgid, *groups;
+	int ngroups, i, count = 0;
+
+	uid  = crgetuid(kcred);
+	ruid = crgetruid(kcred);
+	suid = crgetsuid(kcred);
+
+	gid  = crgetgid(kcred);
+	rgid = crgetrgid(kcred);
+	sgid = crgetsgid(kcred);
+
+	crhold(kcred);
+	ngroups = crgetngroups(kcred);
+	groups  = crgetgroups(kcred);
+
+	memset(str, 0, GROUP_STR_SIZE);
+	for (i = 0; i < ngroups; i++) {
+		count += sprintf(str + count, "%d ", groups[i]);
+
+		if (count > (GROUP_STR_SIZE - GROUP_STR_REDZONE)) {
+			splat_vprint(file, SPLAT_CRED_TEST2_NAME,
+				     "Failed too many group entries for temp "
+				     "buffer: %d, %s\n", ngroups, str);
+			return -ENOSPC;
+		}
+	}
+
+	crfree(kcred);
+
+	splat_vprint(file, SPLAT_CRED_TEST2_NAME,
+		     "uid: %d ruid: %d suid: %d "
+		     "gid: %d rgid: %d sgid: %d\n",
+		     uid, ruid, suid, gid, rgid, sgid);
+	splat_vprint(file, SPLAT_CRED_TEST2_NAME,
+		     "ngroups: %d groups: %s\n", ngroups, str);
+
+	if (uid || ruid || suid || gid || rgid || sgid) {
+		splat_vprint(file, SPLAT_CRED_TEST2_NAME,
+			     "Failed expected all uids+gids to be %d\n", 0);
+		return -EIDRM;
+	}
+
+	if (ngroups > NGROUPS_MAX) {
+		splat_vprint(file, SPLAT_CRED_TEST2_NAME,
+			     "Failed ngroups must not exceed NGROUPS_MAX: "
+			     "%d > %d\n", ngroups, NGROUPS_MAX);
+		return -EIDRM;
+	}
+
+	splat_vprint(file, SPLAT_CRED_TEST2_NAME,
+		     "Success sane kcred: %d\n", 0);
+
+        return 0;
+} /* splat_cred_test2() */
+
+/*
+ * On most/all systems it can be expected that a task with root
+ * permissions also is a member of the root group,  Since the
+ * test suite is always run as root we check first that CRED() is
+ * a member of the root group, and secondly that it is not a member
+ * of our fake group.  This test will break is someone happens to
+ * create group number NGROUPS_MAX-1 and then added root to it.
+ */
+static int
+splat_cred_test3(struct file *file, void *arg)
+{
+	gid_t root_gid, fake_gid;
+	int rc;
+
+	root_gid = 0;
+	fake_gid = NGROUPS_MAX-1;
+
+	rc = groupmember(root_gid, CRED());
+	if (!rc) {
+		splat_vprint(file, SPLAT_CRED_TEST3_NAME,
+			     "Failed root git %d expected to be member "
+			     "of CRED() groups: %d\n", root_gid, rc);
+		return -EIDRM;
+	}
+
+	rc = groupmember(fake_gid, CRED());
+	if (rc) {
+		splat_vprint(file, SPLAT_CRED_TEST3_NAME,
+			     "Failed fake git %d expected not to be member "
+			     "of CRED() groups: %d\n", fake_gid, rc);
+		return -EIDRM;
+	}
+
+	splat_vprint(file, SPLAT_CRED_TEST3_NAME, "Success root gid "
+		     "is a member of the expected groups: %d\n", rc);
+
+	return rc;
+} /* splat_cred_test3() */
+
+splat_subsystem_t *
+splat_cred_init(void)
+{
+        splat_subsystem_t *sub;
+
+        sub = kmalloc(sizeof(*sub), GFP_KERNEL);
+        if (sub == NULL)
+                return NULL;
+
+        memset(sub, 0, sizeof(*sub));
+        strncpy(sub->desc.name, SPLAT_CRED_NAME, SPLAT_NAME_SIZE);
+	strncpy(sub->desc.desc, SPLAT_CRED_DESC, SPLAT_DESC_SIZE);
+        INIT_LIST_HEAD(&sub->subsystem_list);
+	INIT_LIST_HEAD(&sub->test_list);
+        spin_lock_init(&sub->test_lock);
+        sub->desc.id = SPLAT_SUBSYSTEM_CRED;
+
+        SPLAT_TEST_INIT(sub, SPLAT_CRED_TEST1_NAME, SPLAT_CRED_TEST1_DESC,
+	              SPLAT_CRED_TEST1_ID, splat_cred_test1);
+        SPLAT_TEST_INIT(sub, SPLAT_CRED_TEST2_NAME, SPLAT_CRED_TEST2_DESC,
+	              SPLAT_CRED_TEST2_ID, splat_cred_test2);
+        SPLAT_TEST_INIT(sub, SPLAT_CRED_TEST3_NAME, SPLAT_CRED_TEST3_DESC,
+	              SPLAT_CRED_TEST3_ID, splat_cred_test3);
+
+        return sub;
+} /* splat_cred_init() */
+
+void
+splat_cred_fini(splat_subsystem_t *sub)
+{
+        ASSERT(sub);
+
+        SPLAT_TEST_FINI(sub, SPLAT_CRED_TEST3_ID);
+        SPLAT_TEST_FINI(sub, SPLAT_CRED_TEST2_ID);
+        SPLAT_TEST_FINI(sub, SPLAT_CRED_TEST1_ID);
+
+        kfree(sub);
+} /* splat_cred_fini() */
+
+int
+splat_cred_id(void)
+{
+        return SPLAT_SUBSYSTEM_CRED;
+} /* splat_cred_id() */
diff --git a/module/splat/splat-ctl.c b/module/splat/splat-ctl.c
index c8925636a..159103980 100644
--- a/module/splat/splat-ctl.c
+++ b/module/splat/splat-ctl.c
@@ -630,6 +630,7 @@ splat_init(void)
 	SPLAT_SUBSYSTEM_INIT(atomic);
 	SPLAT_SUBSYSTEM_INIT(list);
 	SPLAT_SUBSYSTEM_INIT(generic);
+	SPLAT_SUBSYSTEM_INIT(cred);
 
 	dev = MKDEV(SPLAT_MAJOR, 0);
         if ((rc = register_chrdev_region(dev, SPLAT_MINORS, SPLAT_NAME)))
@@ -676,6 +677,7 @@ splat_fini(void)
         cdev_del(&splat_cdev);
         unregister_chrdev_region(dev, SPLAT_MINORS);
 
+	SPLAT_SUBSYSTEM_FINI(cred);
 	SPLAT_SUBSYSTEM_FINI(generic);
 	SPLAT_SUBSYSTEM_FINI(list);
 	SPLAT_SUBSYSTEM_FINI(atomic);
diff --git a/module/splat/splat-internal.h b/module/splat/splat-internal.h
index 0fa177c02..c1c84d8d1 100644
--- a/module/splat/splat-internal.h
+++ b/module/splat/splat-internal.h
@@ -208,6 +208,7 @@ splat_subsystem_t *splat_kobj_init(void);
 splat_subsystem_t *splat_atomic_init(void);
 splat_subsystem_t *splat_list_init(void);
 splat_subsystem_t *splat_generic_init(void);
+splat_subsystem_t *splat_cred_init(void);
 
 void splat_condvar_fini(splat_subsystem_t *);
 void splat_kmem_fini(splat_subsystem_t *);
@@ -222,6 +223,7 @@ void splat_kobj_fini(splat_subsystem_t *);
 void splat_atomic_fini(splat_subsystem_t *);
 void splat_list_fini(splat_subsystem_t *);
 void splat_generic_fini(splat_subsystem_t *);
+void splat_cred_fini(splat_subsystem_t *);
 
 int splat_condvar_id(void);
 int splat_kmem_id(void);
@@ -236,5 +238,6 @@ int splat_kobj_id(void);
 int splat_atomic_id(void);
 int splat_list_id(void);
 int splat_generic_id(void);
+int splat_cred_id(void);
 
 #endif /* _SPLAT_INTERNAL_H */
diff --git a/spl_config.h.in b/spl_config.h.in
index 3b07d993c..582a47603 100644
--- a/spl_config.h.in
+++ b/spl_config.h.in
@@ -36,6 +36,9 @@
 /* class_device_create() is available */
 #undef HAVE_CLASS_DEVICE_CREATE
 
+/* struct cred exists */
+#undef HAVE_CRED_STRUCT
+
 /* unnumbered sysctl support exists */
 #undef HAVE_CTL_UNNUMBERED
 
@@ -72,6 +75,9 @@
 /* global_page_state() is available */
 #undef HAVE_GLOBAL_PAGE_STATE
 
+/* groups_search() is available */
+#undef HAVE_GROUPS_SEARCH
+
 /* init_utsname() is available */
 #undef HAVE_INIT_UTSNAME