From 98f842e675f96ffac96e6c50315790912b2812be 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 --- include/linux/ipc_namespace.h | 2 ++ include/linux/pid_namespace.h | 1 + include/linux/proc_fs.h | 7 ++++++- include/linux/user_namespace.h | 1 + include/linux/utsname.h | 1 + 5 files changed, 11 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h index f03af702a39d..fe771978e877 100644 --- a/include/linux/ipc_namespace.h +++ b/include/linux/ipc_namespace.h @@ -67,6 +67,8 @@ struct ipc_namespace { /* user_ns which owns the ipc ns */ struct user_namespace *user_ns; + + unsigned int proc_inum; }; extern struct ipc_namespace init_ipc_ns; diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index 4c96acdb2489..bf285999273a 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -37,6 +37,7 @@ struct pid_namespace { kgid_t pid_gid; int hide_pid; int reboot; /* group exit code if this pidns was rebooted */ + unsigned int proc_inum; }; extern struct pid_namespace init_pid_ns; diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index bf1d000fbba6..2e24018b7cec 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -28,7 +28,11 @@ struct mm_struct; */ enum { - PROC_ROOT_INO = 1, + PROC_ROOT_INO = 1, + PROC_IPC_INIT_INO = 0xEFFFFFFFU, + PROC_UTS_INIT_INO = 0xEFFFFFFEU, + PROC_USER_INIT_INO = 0xEFFFFFFDU, + PROC_PID_INIT_INO = 0xEFFFFFFCU, }; /* @@ -263,6 +267,7 @@ struct proc_ns_operations { void *(*get)(struct task_struct *task); void (*put)(void *ns); int (*install)(struct nsproxy *nsproxy, void *ns); + unsigned int (*inum)(void *ns); }; extern const struct proc_ns_operations netns_operations; extern const struct proc_ns_operations utsns_operations; diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 17651f08d67f..b9bd2e6c73cc 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -25,6 +25,7 @@ struct user_namespace { struct user_namespace *parent; kuid_t owner; kgid_t group; + unsigned int proc_inum; }; extern struct user_namespace init_user_ns; diff --git a/include/linux/utsname.h b/include/linux/utsname.h index 221f4a0a7502..239e27733d6c 100644 --- a/include/linux/utsname.h +++ b/include/linux/utsname.h @@ -23,6 +23,7 @@ struct uts_namespace { struct kref kref; struct new_utsname name; struct user_namespace *user_ns; + unsigned int proc_inum; }; extern struct uts_namespace init_uts_ns; -- cgit v1.2.3