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 --- kernel/pid.c | 1 + kernel/pid_namespace.c | 12 ++++++++++++ kernel/user.c | 2 ++ kernel/user_namespace.c | 15 +++++++++++++++ kernel/utsname.c | 17 ++++++++++++++++- 5 files changed, 46 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/pid.c b/kernel/pid.c index 6e8da291de49..3026ddae0a34 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -80,6 +80,7 @@ struct pid_namespace init_pid_ns = { .level = 0, .child_reaper = &init_task, .user_ns = &init_user_ns, + .proc_inum = PROC_PID_INIT_INO, }; EXPORT_SYMBOL_GPL(init_pid_ns); 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) diff --git a/kernel/user.c b/kernel/user.c index 750acffbe9ec..33acb5e53a5f 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -16,6 +16,7 @@ #include #include #include +#include /* * userns count is 1 for root user, 1 for init_uts_ns, @@ -51,6 +52,7 @@ struct user_namespace init_user_ns = { }, .owner = GLOBAL_ROOT_UID, .group = GLOBAL_ROOT_GID, + .proc_inum = PROC_USER_INIT_INO, }; EXPORT_SYMBOL_GPL(init_user_ns); diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 89f6eaed067a..f5975ccf9348 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -58,6 +58,7 @@ int create_user_ns(struct cred *new) struct user_namespace *ns, *parent_ns = new->user_ns; kuid_t owner = new->euid; kgid_t group = new->egid; + int ret; /* The creator needs a mapping in the parent user namespace * or else we won't be able to reasonably tell userspace who @@ -71,6 +72,12 @@ int create_user_ns(struct cred *new) if (!ns) return -ENOMEM; + ret = proc_alloc_inum(&ns->proc_inum); + if (ret) { + kmem_cache_free(user_ns_cachep, ns); + return ret; + } + kref_init(&ns->kref); /* Leave the new->user_ns reference with the new user namespace. */ ns->parent = parent_ns; @@ -103,6 +110,7 @@ void free_user_ns(struct kref *kref) container_of(kref, struct user_namespace, kref); parent = ns->parent; + proc_free_inum(ns->proc_inum); kmem_cache_free(user_ns_cachep, ns); put_user_ns(parent); } @@ -808,12 +816,19 @@ static int userns_install(struct nsproxy *nsproxy, void *ns) return commit_creds(cred); } +static unsigned int userns_inum(void *ns) +{ + struct user_namespace *user_ns = ns; + return user_ns->proc_inum; +} + const struct proc_ns_operations userns_operations = { .name = "user", .type = CLONE_NEWUSER, .get = userns_get, .put = userns_put, .install = userns_install, + .inum = userns_inum, }; static __init int user_namespaces_init(void) diff --git a/kernel/utsname.c b/kernel/utsname.c index fdc619eb61ef..f6336d51d64c 100644 --- a/kernel/utsname.c +++ b/kernel/utsname.c @@ -36,11 +36,18 @@ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns, struct uts_namespace *old_ns) { struct uts_namespace *ns; + int err; ns = create_uts_ns(); if (!ns) return ERR_PTR(-ENOMEM); + err = proc_alloc_inum(&ns->proc_inum); + if (err) { + kfree(ns); + return ERR_PTR(err); + } + down_read(&uts_sem); memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); ns->user_ns = get_user_ns(user_ns); @@ -77,6 +84,7 @@ void free_uts_ns(struct kref *kref) ns = container_of(kref, struct uts_namespace, kref); put_user_ns(ns->user_ns); + proc_free_inum(ns->proc_inum); kfree(ns); } @@ -114,11 +122,18 @@ static int utsns_install(struct nsproxy *nsproxy, void *new) return 0; } +static unsigned int utsns_inum(void *vp) +{ + struct uts_namespace *ns = vp; + + return ns->proc_inum; +} + const struct proc_ns_operations utsns_operations = { .name = "uts", .type = CLONE_NEWUTS, .get = utsns_get, .put = utsns_put, .install = utsns_install, + .inum = utsns_inum, }; - -- cgit