From e1405a6b24b7f9b84aee7aff6db09e5ca5c17cec Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 15 Jun 2011 10:21:48 -0700 Subject: proc: Usable inode numbers for the namespace file descriptors. Assign a unique proc inode to each namespace, and use that inode number to ensure we only allocate at most one proc inode for every namespace in proc. A single proc inode per namespace allows userspace to test to see if two processes are in the same namespace. This has been a long requested feature and only blocked because a naive implementation would put the id in a global space and would ultimately require having a namespace for the names of namespaces, making migration and certain virtualization tricks impossible. We still don't have per superblock inode numbers for proc, which appears necessary for application unaware checkpoint/restart and migrations (if the application is using namespace file descriptors) but that is now allowd by the design if it becomes important. I have preallocated the ipc and uts initial proc inode numbers so their structures can be statically initialized. Signed-off-by: Eric W. Biederman (cherry picked from commit 98f842e675f96ffac96e6c50315790912b2812be) --- include/linux/user_namespace.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/user_namespace.h') diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index faf4679..5ecc988 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -14,6 +14,7 @@ struct user_namespace { struct hlist_head uidhash_table[UIDHASH_SZ]; struct user_struct *creator; struct work_struct destroyer; + unsigned int proc_inum; }; extern struct user_namespace init_user_ns; -- cgit v1.1