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authorEric W. Biederman <ebiederm@xmission.com>2011-06-15 10:21:48 -0700
committerZiyan <jaraidaniel@gmail.com>2016-03-11 16:08:59 +0100
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tree3480b8e0e625b0036af678e672a6491225e71ab6 /include/linux/user_namespace.h
parenta6bf34a158d63bc888bb8c89b86cbc95e5d986c3 (diff)
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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 <ebiederm@xmission.com> (cherry picked from commit 98f842e675f96ffac96e6c50315790912b2812be)
Diffstat (limited to 'include/linux/user_namespace.h')
-rw-r--r--include/linux/user_namespace.h1
1 files changed, 1 insertions, 0 deletions
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;