[PATCH 2/4] Expose may_setuid() in user.h

[Dan Smith <danms-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

Make this helper available to others.

Signed-off-by: Dan Smith <danms-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
---
 include/linux/user.h |    9 +++++++++
 kernel/user.c        |   16 +++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletions(-)

diff --git a/include/linux/user.h b/include/linux/user.h
index 68daf84..713bae7 100644
--- a/include/linux/user.h
+++ b/include/linux/user.h
@@ -1 +1,10 @@
+#ifndef _LINUX_USER_H
+#define _LINUX_USER_H
+
 #include <asm/user.h>
+#include <linux/sched.h>
+
+extern int may_setuid(struct user_namespace *ns, uid_t uid);
+extern int may_setgid(struct group_info *groupinfo, gid_t gid);
+
+#endif
diff --git a/kernel/user.c b/kernel/user.c
index a535ed6..38b8b50 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -604,7 +604,7 @@ int checkpoint_user(struct ckpt_ctx *ctx, void *ptr)
 	return do_checkpoint_user(ctx, (struct user_struct *) ptr);
 }
 
-static int may_setuid(struct user_namespace *ns, uid_t uid)
+int may_setuid(struct user_namespace *ns, uid_t uid)
 {
 	/*
 	 * this next check will one day become
@@ -631,6 +631,20 @@ static int may_setuid(struct user_namespace *ns, uid_t uid)
 	return 0;
 }
 
+int may_setgid(struct group_info *groupinfo, gid_t gid)
+{
+	if (capable(CAP_SETGID))
+		return 1;
+
+	if (current_cred_xxx(group_info) != groupinfo)
+		return 0;
+
+	if (in_egroup_p(gid))
+		return 1;
+
+	return 0;
+}
+
 static struct user_struct *do_restore_user(struct ckpt_ctx *ctx)
 {
 	struct user_struct *u;
-- 
1.6.0.4