diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2011-06-15 21:21:48 +0400 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2012-11-20 16:19:49 +0400 |
| commit | 98f842e675f96ffac96e6c50315790912b2812be (patch) | |
| tree | ed4dee9a6e54e3443e9f3f1614c8a2fcf9b31e0a /kernel/pid_namespace.c | |
| parent | bf056bfa80596a5d14b26b17276a56a0dcb080e5 (diff) | |
| download | linux-98f842e675f96ffac96e6c50315790912b2812be.tar.xz | |
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>
Diffstat (limited to 'kernel/pid_namespace.c')
| -rw-r--r-- | kernel/pid_namespace.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index 68508d330634..560da0dab230 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -107,6 +107,10 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns if (ns->pid_cachep == NULL) goto out_free_map; + err = proc_alloc_inum(&ns->proc_inum); + if (err) + goto out_free_map; + kref_init(&ns->kref); ns->level = level; ns->parent = get_pid_ns(parent_pid_ns); @@ -133,6 +137,7 @@ static void destroy_pid_namespace(struct pid_namespace *ns) { int i; + proc_free_inum(ns->proc_inum); for (i = 0; i < PIDMAP_ENTRIES; i++) kfree(ns->pidmap[i].page); put_user_ns(ns->user_ns); @@ -345,12 +350,19 @@ static int pidns_install(struct nsproxy *nsproxy, void *ns) return 0; } +static unsigned int pidns_inum(void *ns) +{ + struct pid_namespace *pid_ns = ns; + return pid_ns->proc_inum; +} + const struct proc_ns_operations pidns_operations = { .name = "pid", .type = CLONE_NEWPID, .get = pidns_get, .put = pidns_put, .install = pidns_install, + .inum = pidns_inum, }; static __init int pid_namespaces_init(void) |