From 142e1d1d5f088e7a38659daca6e84a730967774a Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 26 Jul 2012 01:13:20 -0700 Subject: userns: Allow unprivileged use of setns. - Push the permission check from the core setns syscall into the setns install methods where the user namespace of the target namespace can be determined, and used in a ns_capable call. Acked-by: Serge Hallyn Signed-off-by: "Eric W. Biederman" --- ipc/namespace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'ipc') diff --git a/ipc/namespace.c b/ipc/namespace.c index f362298c5ce..6ed33c05cb6 100644 --- a/ipc/namespace.c +++ b/ipc/namespace.c @@ -161,8 +161,12 @@ static void ipcns_put(void *ns) return put_ipc_ns(ns); } -static int ipcns_install(struct nsproxy *nsproxy, void *ns) +static int ipcns_install(struct nsproxy *nsproxy, void *new) { + struct ipc_namespace *ns = new; + if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) + return -EPERM; + /* Ditch state from the old ipc namespace */ exit_sem(current); put_ipc_ns(nsproxy->ipc_ns); -- cgit v1.2.3 From bcf58e725ddc45d31addbc6627d4f0edccc824c1 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 26 Jul 2012 04:02:49 -0700 Subject: userns: Make create_new_namespaces take a user_ns parameter Modify create_new_namespaces to explicitly take a user namespace parameter, instead of implicitly through the task_struct. This allows an implementation of unshare(CLONE_NEWUSER) where the new user namespace is not stored onto the current task_struct until after all of the namespaces are created. Acked-by: Serge Hallyn Signed-off-by: "Eric W. Biederman" --- ipc/namespace.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'ipc') diff --git a/ipc/namespace.c b/ipc/namespace.c index 6ed33c05cb6..72c86827779 100644 --- a/ipc/namespace.c +++ b/ipc/namespace.c @@ -16,7 +16,7 @@ #include "util.h" -static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk, +static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns, struct ipc_namespace *old_ns) { struct ipc_namespace *ns; @@ -46,19 +46,17 @@ static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk, ipcns_notify(IPCNS_CREATED); register_ipcns_notifier(ns); - ns->user_ns = get_user_ns(task_cred_xxx(tsk, user_ns)); + ns->user_ns = get_user_ns(user_ns); return ns; } struct ipc_namespace *copy_ipcs(unsigned long flags, - struct task_struct *tsk) + struct user_namespace *user_ns, struct ipc_namespace *ns) { - struct ipc_namespace *ns = tsk->nsproxy->ipc_ns; - if (!(flags & CLONE_NEWIPC)) return get_ipc_ns(ns); - return create_ipc_ns(tsk, ns); + return create_ipc_ns(user_ns, ns); } /* -- cgit v1.2.3 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 --- ipc/msgutil.c | 2 ++ ipc/namespace.c | 16 ++++++++++++++++ 2 files changed, 18 insertions(+) (limited to 'ipc') diff --git a/ipc/msgutil.c b/ipc/msgutil.c index 26143d377c9..6471f1bdae9 100644 --- a/ipc/msgutil.c +++ b/ipc/msgutil.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include "util.h" @@ -30,6 +31,7 @@ DEFINE_SPINLOCK(mq_lock); struct ipc_namespace init_ipc_ns = { .count = ATOMIC_INIT(1), .user_ns = &init_user_ns, + .proc_inum = PROC_IPC_INIT_INO, }; atomic_t nr_ipc_ns = ATOMIC_INIT(1); diff --git a/ipc/namespace.c b/ipc/namespace.c index 72c86827779..cf3386a51de 100644 --- a/ipc/namespace.c +++ b/ipc/namespace.c @@ -26,9 +26,16 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns, if (ns == NULL) return ERR_PTR(-ENOMEM); + err = proc_alloc_inum(&ns->proc_inum); + if (err) { + kfree(ns); + return ERR_PTR(err); + } + atomic_set(&ns->count, 1); err = mq_init_ns(ns); if (err) { + proc_free_inum(ns->proc_inum); kfree(ns); return ERR_PTR(err); } @@ -111,6 +118,7 @@ static void free_ipc_ns(struct ipc_namespace *ns) */ ipcns_notify(IPCNS_REMOVED); put_user_ns(ns->user_ns); + proc_free_inum(ns->proc_inum); kfree(ns); } @@ -172,10 +180,18 @@ static int ipcns_install(struct nsproxy *nsproxy, void *new) return 0; } +static unsigned int ipcns_inum(void *vp) +{ + struct ipc_namespace *ns = vp; + + return ns->proc_inum; +} + const struct proc_ns_operations ipcns_operations = { .name = "ipc", .type = CLONE_NEWIPC, .get = ipcns_get, .put = ipcns_put, .install = ipcns_install, + .inum = ipcns_inum, }; -- cgit v1.2.3