3 files changed, 31 insertions, 7 deletions
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index 5ea470eb4d76..4b20375f3783 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -6,6 +6,7 @@
 #define _LINUX_PROC_NS_H
 
 #include <linux/ns_common.h>
+#include <uapi/linux/nsfs.h>
 
 struct pid_namespace;
 struct nsset;
@@ -39,13 +40,14 @@ extern const struct proc_ns_operations timens_for_children_operations;
  * We always define these enumerators
  */
 enum {
-	PROC_ROOT_INO		= 1,
-	PROC_IPC_INIT_INO	= 0xEFFFFFFFU,
-	PROC_UTS_INIT_INO	= 0xEFFFFFFEU,
-	PROC_USER_INIT_INO	= 0xEFFFFFFDU,
-	PROC_PID_INIT_INO	= 0xEFFFFFFCU,
-	PROC_CGROUP_INIT_INO	= 0xEFFFFFFBU,
-	PROC_TIME_INIT_INO	= 0xEFFFFFFAU,
+	PROC_IPC_INIT_INO	= IPC_NS_INIT_INO,
+	PROC_UTS_INIT_INO	= UTS_NS_INIT_INO,
+	PROC_USER_INIT_INO	= USER_NS_INIT_INO,
+	PROC_PID_INIT_INO	= PID_NS_INIT_INO,
+	PROC_CGROUP_INIT_INO	= CGROUP_NS_INIT_INO,
+	PROC_TIME_INIT_INO	= TIME_NS_INIT_INO,
+	PROC_NET_INIT_INO	= NET_NS_INIT_INO,
+	PROC_MNT_INIT_INO	= MNT_NS_INIT_INO,
 };
 
 #ifdef CONFIG_PROC_FS
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 0098b0ce8ccb..28238a3edbc1 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -60,6 +60,17 @@
 #define RENAME_EXCHANGE		(1 << 1)	/* Exchange source and dest */
 #define RENAME_WHITEOUT		(1 << 2)	/* Whiteout source */
 
+/*
+ * The root inode of procfs is guaranteed to always have the same inode number.
+ * For programs that make heavy use of procfs, verifying that the root is a
+ * real procfs root and using openat2(RESOLVE_{NO_{XDEV,MAGICLINKS},BENEATH})
+ * will allow you to make sure you are never tricked into operating on the
+ * wrong procfs file.
+ */
+enum procfs_ino {
+	PROCFS_ROOT_INO = 1,
+};
+
 struct file_clone_range {
 	__s64 src_fd;
 	__u64 src_offset;
diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h
index 34127653fd00..97d8d80d139f 100644
--- a/include/uapi/linux/nsfs.h
+++ b/include/uapi/linux/nsfs.h
@@ -42,4 +42,15 @@ struct mnt_ns_info {
 /* Get previous namespace. */
 #define NS_MNT_GET_PREV		_IOR(NSIO, 12, struct mnt_ns_info)
 
+enum init_ns_ino {
+	IPC_NS_INIT_INO		= 0xEFFFFFFFU,
+	UTS_NS_INIT_INO		= 0xEFFFFFFEU,
+	USER_NS_INIT_INO	= 0xEFFFFFFDU,
+	PID_NS_INIT_INO		= 0xEFFFFFFCU,
+	CGROUP_NS_INIT_INO	= 0xEFFFFFFBU,
+	TIME_NS_INIT_INO	= 0xEFFFFFFAU,
+	NET_NS_INIT_INO		= 0xEFFFFFF9U,
+	MNT_NS_INIT_INO		= 0xEFFFFFF8U,
+};
+
 #endif /* __LINUX_NSFS_H */