diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/Makefile | 1 | ||||
| -rw-r--r-- | kernel/ns_cgroup.c | 100 | ||||
| -rw-r--r-- | kernel/nsproxy.c | 17 |
3 files changed, 117 insertions, 1 deletions
diff --git a/kernel/Makefile b/kernel/Makefile index a50a6debe5f..32b2d8bdc9f 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -40,6 +40,7 @@ obj-$(CONFIG_CGROUPS) += cgroup.o obj-$(CONFIG_CGROUP_DEBUG) += cgroup_debug.o obj-$(CONFIG_CPUSETS) += cpuset.o obj-$(CONFIG_CGROUP_CPUACCT) += cpu_acct.o +obj-$(CONFIG_CGROUP_NS) += ns_cgroup.o obj-$(CONFIG_IKCONFIG) += configs.o obj-$(CONFIG_STOP_MACHINE) += stop_machine.o obj-$(CONFIG_AUDIT) += audit.o auditfilter.o diff --git a/kernel/ns_cgroup.c b/kernel/ns_cgroup.c new file mode 100644 index 00000000000..aead4d69f62 --- /dev/null +++ b/kernel/ns_cgroup.c @@ -0,0 +1,100 @@ +/* + * ns_cgroup.c - namespace cgroup subsystem + * + * Copyright 2006, 2007 IBM Corp + */ + +#include <linux/module.h> +#include <linux/cgroup.h> +#include <linux/fs.h> + +struct ns_cgroup { + struct cgroup_subsys_state css; + spinlock_t lock; +}; + +struct cgroup_subsys ns_subsys; + +static inline struct ns_cgroup *cgroup_to_ns( + struct cgroup *cgroup) +{ + return container_of(cgroup_subsys_state(cgroup, ns_subsys_id), + struct ns_cgroup, css); +} + +int ns_cgroup_clone(struct task_struct *task) +{ + return cgroup_clone(task, &ns_subsys); +} + +/* + * Rules: + * 1. you can only enter a cgroup which is a child of your current + * cgroup + * 2. you can only place another process into a cgroup if + * a. you have CAP_SYS_ADMIN + * b. your cgroup is an ancestor of task's destination cgroup + * (hence either you are in the same cgroup as task, or in an + * ancestor cgroup thereof) + */ +static int ns_can_attach(struct cgroup_subsys *ss, + struct cgroup *new_cgroup, struct task_struct *task) +{ + struct cgroup *orig; + + if (current != task) { + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (!cgroup_is_descendant(new_cgroup)) + return -EPERM; + } + + if (atomic_read(&new_cgroup->count) != 0) + return -EPERM; + + orig = task_cgroup(task, ns_subsys_id); + if (orig && orig != new_cgroup->parent) + return -EPERM; + + return 0; +} + +/* + * Rules: you can only create a cgroup if + * 1. you are capable(CAP_SYS_ADMIN) + * 2. the target cgroup is a descendant of your own cgroup + */ +static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss, + struct cgroup *cgroup) +{ + struct ns_cgroup *ns_cgroup; + + if (!capable(CAP_SYS_ADMIN)) + return ERR_PTR(-EPERM); + if (!cgroup_is_descendant(cgroup)) + return ERR_PTR(-EPERM); + + ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL); + if (!ns_cgroup) + return ERR_PTR(-ENOMEM); + spin_lock_init(&ns_cgroup->lock); + return &ns_cgroup->css; +} + +static void ns_destroy(struct cgroup_subsys *ss, + struct cgroup *cgroup) +{ + struct ns_cgroup *ns_cgroup; + + ns_cgroup = cgroup_to_ns(cgroup); + kfree(ns_cgroup); +} + +struct cgroup_subsys ns_subsys = { + .name = "ns", + .can_attach = ns_can_attach, + .create = ns_create, + .destroy = ns_destroy, + .subsys_id = ns_subsys_id, +}; diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index 049e7c0ac56..ac99837e7a0 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -156,7 +156,14 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk) goto out; } + err = ns_cgroup_clone(tsk); + if (err) { + put_nsproxy(new_ns); + goto out; + } + tsk->nsproxy = new_ns; + out: put_nsproxy(old_ns); return err; @@ -196,8 +203,16 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags, *new_nsp = create_new_namespaces(unshare_flags, current, new_fs ? new_fs : current->fs); - if (IS_ERR(*new_nsp)) + if (IS_ERR(*new_nsp)) { err = PTR_ERR(*new_nsp); + goto out; + } + + err = ns_cgroup_clone(current); + if (err) + put_nsproxy(*new_nsp); + +out: return err; } |