diff --git a/fs/proc/base.c b/fs/proc/base.c
index 138cff4b05d..acd1960c28a 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2991,6 +2991,11 @@ static int proc_gid_map_open(struct inode *inode, struct file *file)
 	return proc_id_map_open(inode, file, &proc_gid_seq_operations);
 }
 
+static int proc_projid_map_open(struct inode *inode, struct file *file)
+{
+	return proc_id_map_open(inode, file, &proc_projid_seq_operations);
+}
+
 static const struct file_operations proc_uid_map_operations = {
 	.open		= proc_uid_map_open,
 	.write		= proc_uid_map_write,
@@ -3006,6 +3011,14 @@ static const struct file_operations proc_gid_map_operations = {
 	.llseek		= seq_lseek,
 	.release	= proc_id_map_release,
 };
+
+static const struct file_operations proc_projid_map_operations = {
+	.open		= proc_projid_map_open,
+	.write		= proc_projid_map_write,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= proc_id_map_release,
+};
 #endif /* CONFIG_USER_NS */
 
 static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
@@ -3113,6 +3126,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_USER_NS
 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
+	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
 #endif
 };
 
@@ -3476,6 +3490,7 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_USER_NS
 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
+	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
 #endif
 };
 
diff --git a/include/linux/projid.h b/include/linux/projid.h
new file mode 100644
index 00000000000..36517b95be5
--- /dev/null
+++ b/include/linux/projid.h
@@ -0,0 +1,104 @@
+#ifndef _LINUX_PROJID_H
+#define _LINUX_PROJID_H
+
+/*
+ * A set of types for the internal kernel types representing project ids.
+ *
+ * The types defined in this header allow distinguishing which project ids in
+ * the kernel are values used by userspace and which project id values are
+ * the internal kernel values.  With the addition of user namespaces the values
+ * can be different.  Using the type system makes it possible for the compiler
+ * to detect when we overlook these differences.
+ *
+ */
+#include <linux/types.h>
+
+struct user_namespace;
+extern struct user_namespace init_user_ns;
+
+typedef __kernel_uid32_t projid_t;
+
+#ifdef CONFIG_UIDGID_STRICT_TYPE_CHECKS
+
+typedef struct {
+	projid_t val;
+} kprojid_t;
+
+static inline projid_t __kprojid_val(kprojid_t projid)
+{
+	return projid.val;
+}
+
+#define KPROJIDT_INIT(value) (kprojid_t){ value }
+
+#else
+
+typedef projid_t kprojid_t;
+
+static inline projid_t __kprojid_val(kprojid_t projid)
+{
+	return projid;
+}
+
+#define KPROJIDT_INIT(value) ((kprojid_t) value )
+
+#endif
+
+#define INVALID_PROJID KPROJIDT_INIT(-1)
+#define OVERFLOW_PROJID 65534
+
+static inline bool projid_eq(kprojid_t left, kprojid_t right)
+{
+	return __kprojid_val(left) == __kprojid_val(right);
+}
+
+static inline bool projid_lt(kprojid_t left, kprojid_t right)
+{
+	return __kprojid_val(left) < __kprojid_val(right);
+}
+
+static inline bool projid_valid(kprojid_t projid)
+{
+	return !projid_eq(projid, INVALID_PROJID);
+}
+
+#ifdef CONFIG_USER_NS
+
+extern kprojid_t make_kprojid(struct user_namespace *from, projid_t projid);
+
+extern projid_t from_kprojid(struct user_namespace *to, kprojid_t projid);
+extern projid_t from_kprojid_munged(struct user_namespace *to, kprojid_t projid);
+
+static inline bool kprojid_has_mapping(struct user_namespace *ns, kprojid_t projid)
+{
+	return from_kprojid(ns, projid) != (projid_t)-1;
+}
+
+#else
+
+static inline kprojid_t make_kprojid(struct user_namespace *from, projid_t projid)
+{
+	return KPROJIDT_INIT(projid);
+}
+
+static inline projid_t from_kprojid(struct user_namespace *to, kprojid_t kprojid)
+{
+	return __kprojid_val(kprojid);
+}
+
+static inline projid_t from_kprojid_munged(struct user_namespace *to, kprojid_t kprojid)
+{
+	projid_t projid = from_kprojid(to, kprojid);
+	if (projid == (projid_t)-1)
+		projid = OVERFLOW_PROJID;
+	return projid;
+}
+
+static inline bool kprojid_has_mapping(struct user_namespace *ns, kprojid_t projid)
+{
+	return true;
+}
+
+#endif /* CONFIG_USER_NS */
+
+#endif /* _LINUX_PROJID_H */
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 4e72922e5a7..95142cae446 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -20,6 +20,7 @@ struct uid_gid_map {	/* 64 bytes -- 1 cache line */
 struct user_namespace {
 	struct uid_gid_map	uid_map;
 	struct uid_gid_map	gid_map;
+	struct uid_gid_map	projid_map;
 	struct kref		kref;
 	struct user_namespace	*parent;
 	kuid_t			owner;
@@ -49,8 +50,10 @@ static inline void put_user_ns(struct user_namespace *ns)
 struct seq_operations;
 extern struct seq_operations proc_uid_seq_operations;
 extern struct seq_operations proc_gid_seq_operations;
+extern struct seq_operations proc_projid_seq_operations;
 extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
 extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);
+extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);
 #else
 
 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
diff --git a/kernel/user.c b/kernel/user.c
index b815fefbe76..750acffbe9e 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -38,6 +38,14 @@ struct user_namespace init_user_ns = {
 			.count = 4294967295U,
 		},
 	},
+	.projid_map = {
+		.nr_extents = 1,
+		.extent[0] = {
+			.first = 0,
+			.lower_first = 0,
+			.count = 4294967295U,
+		},
+	},
 	.kref = {
 		.refcount	= ATOMIC_INIT(3),
 	},
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 86602316422..456a6b9fba3 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -19,6 +19,7 @@
 #include <linux/fs.h>
 #include <linux/uaccess.h>
 #include <linux/ctype.h>
+#include <linux/projid.h>
 
 static struct kmem_cache *user_ns_cachep __read_mostly;
 
@@ -295,6 +296,75 @@ gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid)
 }
 EXPORT_SYMBOL(from_kgid_munged);
 
+/**
+ *	make_kprojid - Map a user-namespace projid pair into a kprojid.
+ *	@ns:  User namespace that the projid is in
+ *	@projid: Project identifier
+ *
+ *	Maps a user-namespace uid pair into a kernel internal kuid,
+ *	and returns that kuid.
+ *
+ *	When there is no mapping defined for the user-namespace projid
+ *	pair INVALID_PROJID is returned.  Callers are expected to test
+ *	for and handle handle INVALID_PROJID being returned.  INVALID_PROJID
+ *	may be tested for using projid_valid().
+ */
+kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid)
+{
+	/* Map the uid to a global kernel uid */
+	return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid));
+}
+EXPORT_SYMBOL(make_kprojid);
+
+/**
+ *	from_kprojid - Create a projid from a kprojid user-namespace pair.
+ *	@targ: The user namespace we want a projid in.
+ *	@kprojid: The kernel internal project identifier to start with.
+ *
+ *	Map @kprojid into the user-namespace specified by @targ and
+ *	return the resulting projid.
+ *
+ *	There is always a mapping into the initial user_namespace.
+ *
+ *	If @kprojid has no mapping in @targ (projid_t)-1 is returned.
+ */
+projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid)
+{
+	/* Map the uid from a global kernel uid */
+	return map_id_up(&targ->projid_map, __kprojid_val(kprojid));
+}
+EXPORT_SYMBOL(from_kprojid);
+
+/**
+ *	from_kprojid_munged - Create a projiid from a kprojid user-namespace pair.
+ *	@targ: The user namespace we want a projid in.
+ *	@kprojid: The kernel internal projid to start with.
+ *
+ *	Map @kprojid into the user-namespace specified by @targ and
+ *	return the resulting projid.
+ *
+ *	There is always a mapping into the initial user_namespace.
+ *
+ *	Unlike from_kprojid from_kprojid_munged never fails and always
+ *	returns a valid projid.  This makes from_kprojid_munged
+ *	appropriate for use in syscalls like stat and where
+ *	failing the system call and failing to provide a valid projid are
+ *	not an options.
+ *
+ *	If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned.
+ */
+projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid)
+{
+	projid_t projid;
+	projid = from_kprojid(targ, kprojid);
+
+	if (projid == (projid_t) -1)
+		projid = OVERFLOW_PROJID;
+	return projid;
+}
+EXPORT_SYMBOL(from_kprojid_munged);
+
+
 static int uid_m_show(struct seq_file *seq, void *v)
 {
 	struct user_namespace *ns = seq->private;
@@ -337,6 +407,27 @@ static int gid_m_show(struct seq_file *seq, void *v)
 	return 0;
 }
 
+static int projid_m_show(struct seq_file *seq, void *v)
+{
+	struct user_namespace *ns = seq->private;
+	struct uid_gid_extent *extent = v;
+	struct user_namespace *lower_ns;
+	projid_t lower;
+
+	lower_ns = seq_user_ns(seq);
+	if ((lower_ns == ns) && lower_ns->parent)
+		lower_ns = lower_ns->parent;
+
+	lower = from_kprojid(lower_ns, KPROJIDT_INIT(extent->lower_first));
+
+	seq_printf(seq, "%10u %10u %10u\n",
+		extent->first,
+		lower,
+		extent->count);
+
+	return 0;
+}
+
 static void *m_start(struct seq_file *seq, loff_t *ppos, struct uid_gid_map *map)
 {
 	struct uid_gid_extent *extent = NULL;
@@ -362,6 +453,13 @@ static void *gid_m_start(struct seq_file *seq, loff_t *ppos)
 	return m_start(seq, ppos, &ns->gid_map);
 }
 
+static void *projid_m_start(struct seq_file *seq, loff_t *ppos)
+{
+	struct user_namespace *ns = seq->private;
+
+	return m_start(seq, ppos, &ns->projid_map);
+}
+
 static void *m_next(struct seq_file *seq, void *v, loff_t *pos)
 {
 	(*pos)++;
@@ -387,6 +485,13 @@ struct seq_operations proc_gid_seq_operations = {
 	.show = gid_m_show,
 };
 
+struct seq_operations proc_projid_seq_operations = {
+	.start = projid_m_start,
+	.stop = m_stop,
+	.next = m_next,
+	.show = projid_m_show,
+};
+
 static DEFINE_MUTEX(id_map_mutex);
 
 static ssize_t map_write(struct file *file, const char __user *buf,
@@ -434,7 +539,7 @@ static ssize_t map_write(struct file *file, const char __user *buf,
 	/* Require the appropriate privilege CAP_SETUID or CAP_SETGID
 	 * over the user namespace in order to set the id mapping.
 	 */
-	if (!ns_capable(ns, cap_setid))
+	if (cap_valid(cap_setid) && !ns_capable(ns, cap_setid))
 		goto out;
 
 	/* Get a buffer */
@@ -584,9 +689,30 @@ ssize_t proc_gid_map_write(struct file *file, const char __user *buf, size_t siz
 			 &ns->gid_map, &ns->parent->gid_map);
 }
 
+ssize_t proc_projid_map_write(struct file *file, const char __user *buf, size_t size, loff_t *ppos)
+{
+	struct seq_file *seq = file->private_data;
+	struct user_namespace *ns = seq->private;
+	struct user_namespace *seq_ns = seq_user_ns(seq);
+
+	if (!ns->parent)
+		return -EPERM;
+
+	if ((seq_ns != ns) && (seq_ns != ns->parent))
+		return -EPERM;
+
+	/* Anyone can set any valid project id no capability needed */
+	return map_write(file, buf, size, ppos, -1,
+			 &ns->projid_map, &ns->parent->projid_map);
+}
+
 static bool new_idmap_permitted(struct user_namespace *ns, int cap_setid,
 				struct uid_gid_map *new_map)
 {
+	/* Allow anyone to set a mapping that doesn't require privilege */
+	if (!cap_valid(cap_setid))
+		return true;
+
 	/* Allow the specified ids if we have the appropriate capability
 	 * (CAP_SETUID or CAP_SETGID) over the parent user namespace.
 	 */