// SPDX-License-Identifier: GPL-2.0-only/** Copyright (C) 2006 IBM Corporation** Author: Serge Hallyn <serue@us.ibm.com>** Jun 2006 - namespaces support* OpenVZ, SWsoft Inc.* Pavel Emelianov <xemul@openvz.org>*/#include <linux/slab.h>#include <linux/export.h>#include <linux/nsproxy.h>#include <linux/init_task.h>#include <linux/mnt_namespace.h>#include <linux/utsname.h>#include <linux/pid_namespace.h>#include <net/net_namespace.h>#include <linux/ipc_namespace.h>#include <linux/time_namespace.h>#include <linux/fs_struct.h>#include <linux/proc_fs.h>#include <linux/proc_ns.h>#include <linux/file.h>#include <linux/syscalls.h>#include <linux/cgroup.h>#include <linux/perf_event.h>static struct kmem_cache *nsproxy_cachep;struct nsproxy init_nsproxy = {.count = REFCOUNT_INIT(1),.uts_ns = &init_uts_ns,#if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC).ipc_ns = &init_ipc_ns,#endif.mnt_ns = NULL,.pid_ns_for_children = &init_pid_ns,#ifdef CONFIG_NET.net_ns = &init_net,#endif#ifdef CONFIG_CGROUPS.cgroup_ns = &init_cgroup_ns,#endif#ifdef CONFIG_TIME_NS.time_ns = &init_time_ns,.time_ns_for_children = &init_time_ns,#endif};static inline struct nsproxy *create_nsproxy(void){struct nsproxy *nsproxy;nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);if (nsproxy)refcount_set(&nsproxy->count, 1);return nsproxy;}/** Create new nsproxy and all of its the associated namespaces.* Return the newly created nsproxy. Do not attach this to the task,* leave it to the caller to do proper locking and attach it to task.*/static struct nsproxy *create_new_namespaces(unsigned long flags,struct task_struct *tsk, struct user_namespace *user_ns,struct fs_struct *new_fs){struct nsproxy *new_nsp;int err;new_nsp = create_nsproxy();if (!new_nsp)return ERR_PTR(-ENOMEM);new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);if (IS_ERR(new_nsp->mnt_ns)) {err = PTR_ERR(new_nsp->mnt_ns);goto out_ns;}new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);if (IS_ERR(new_nsp->uts_ns)) {err = PTR_ERR(new_nsp->uts_ns);goto out_uts;}new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);if (IS_ERR(new_nsp->ipc_ns)) {err = PTR_ERR(new_nsp->ipc_ns);goto out_ipc;}new_nsp->pid_ns_for_children =copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);if (IS_ERR(new_nsp->pid_ns_for_children)) {err = PTR_ERR(new_nsp->pid_ns_for_children);goto out_pid;}new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns,tsk->nsproxy->cgroup_ns);if (IS_ERR(new_nsp->cgroup_ns)) {err = PTR_ERR(new_nsp->cgroup_ns);goto out_cgroup;}new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);if (IS_ERR(new_nsp->net_ns)) {err = PTR_ERR(new_nsp->net_ns);goto out_net;}new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns,tsk->nsproxy->time_ns_for_children);if (IS_ERR(new_nsp->time_ns_for_children)) {err = PTR_ERR(new_nsp->time_ns_for_children);goto out_time;}new_nsp->time_ns = get_time_ns(tsk->nsproxy->time_ns);return new_nsp;out_time:put_net(new_nsp->net_ns);out_net:put_cgroup_ns(new_nsp->cgroup_ns);out_cgroup:put_pid_ns(new_nsp->pid_ns_for_children);out_pid:put_ipc_ns(new_nsp->ipc_ns);out_ipc:put_uts_ns(new_nsp->uts_ns);out_uts:put_mnt_ns(new_nsp->mnt_ns);out_ns:kmem_cache_free(nsproxy_cachep, new_nsp);return ERR_PTR(err);}/** called from clone. This now handles copy for nsproxy and all* namespaces therein.*/int copy_namespaces(unsigned long flags, struct task_struct *tsk){struct nsproxy *old_ns = tsk->nsproxy;struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);struct nsproxy *new_ns;if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |CLONE_NEWPID | CLONE_NEWNET |CLONE_NEWCGROUP | CLONE_NEWTIME)))) {if ((flags & CLONE_VM) ||likely(old_ns->time_ns_for_children == old_ns->time_ns)) {get_nsproxy(old_ns);return 0;}} else if (!ns_capable(user_ns, CAP_SYS_ADMIN))return -EPERM;/** CLONE_NEWIPC must detach from the undolist: after switching* to a new ipc namespace, the semaphore arrays from the old* namespace are unreachable. In clone parlance, CLONE_SYSVSEM* means share undolist with parent, so we must forbid using* it along with CLONE_NEWIPC.*/if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==(CLONE_NEWIPC | CLONE_SYSVSEM))return -EINVAL;new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);if (IS_ERR(new_ns))return PTR_ERR(new_ns);if ((flags & CLONE_VM) == 0)timens_on_fork(new_ns, tsk);tsk->nsproxy = new_ns;return 0;}void free_nsproxy(struct nsproxy *ns){put_mnt_ns(ns->mnt_ns);put_uts_ns(ns->uts_ns);put_ipc_ns(ns->ipc_ns);put_pid_ns(ns->pid_ns_for_children);put_time_ns(ns->time_ns);put_time_ns(ns->time_ns_for_children);put_cgroup_ns(ns->cgroup_ns);put_net(ns->net_ns);kmem_cache_free(nsproxy_cachep, ns);}/** Called from unshare. Unshare all the namespaces part of nsproxy.* On success, returns the new nsproxy.*/int unshare_nsproxy_namespaces(unsigned long unshare_flags,struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs){struct user_namespace *user_ns;int err = 0;if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |CLONE_NEWTIME)))return 0;user_ns = new_cred ? new_cred->user_ns : current_user_ns();if (!ns_capable(user_ns, CAP_SYS_ADMIN))return -EPERM;*new_nsp = create_new_namespaces(unshare_flags, current, user_ns,new_fs ? new_fs : current->fs);if (IS_ERR(*new_nsp)) {err = PTR_ERR(*new_nsp);goto out;}out:return err;}void switch_task_namespaces(struct task_struct *p, struct nsproxy *new){struct nsproxy *ns;might_sleep();task_lock(p);ns = p->nsproxy;p->nsproxy = new;task_unlock(p);if (ns)put_nsproxy(ns);}void exit_task_namespaces(struct task_struct *p){switch_task_namespaces(p, NULL);}int exec_task_namespaces(void){struct task_struct *tsk = current;struct nsproxy *new;if (tsk->nsproxy->time_ns_for_children == tsk->nsproxy->time_ns)return 0;new = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);if (IS_ERR(new))return PTR_ERR(new);timens_on_fork(new, tsk);switch_task_namespaces(tsk, new);return 0;}static int check_setns_flags(unsigned long flags){if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |CLONE_NEWNET | CLONE_NEWTIME | CLONE_NEWUSER |CLONE_NEWPID | CLONE_NEWCGROUP)))return -EINVAL;#ifndef CONFIG_USER_NSif (flags & CLONE_NEWUSER)return -EINVAL;#endif#ifndef CONFIG_PID_NSif (flags & CLONE_NEWPID)return -EINVAL;#endif#ifndef CONFIG_UTS_NSif (flags & CLONE_NEWUTS)return -EINVAL;#endif#ifndef CONFIG_IPC_NSif (flags & CLONE_NEWIPC)return -EINVAL;#endif#ifndef CONFIG_CGROUPSif (flags & CLONE_NEWCGROUP)return -EINVAL;#endif#ifndef CONFIG_NET_NSif (flags & CLONE_NEWNET)return -EINVAL;#endif#ifndef CONFIG_TIME_NSif (flags & CLONE_NEWTIME)return -EINVAL;#endifreturn 0;}static void put_nsset(struct nsset *nsset){unsigned flags = nsset->flags;if (flags & CLONE_NEWUSER)put_cred(nsset_cred(nsset));/** We only created a temporary copy if we attached to more than just* the mount namespace.*/if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS))free_fs_struct(nsset->fs);if (nsset->nsproxy)free_nsproxy(nsset->nsproxy);}static int prepare_nsset(unsigned flags, struct nsset *nsset){struct task_struct *me = current;nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs);if (IS_ERR(nsset->nsproxy))return PTR_ERR(nsset->nsproxy);if (flags & CLONE_NEWUSER)nsset->cred = prepare_creds();elsensset->cred = current_cred();if (!nsset->cred)goto out;/* Only create a temporary copy of fs_struct if we really need to. */if (flags == CLONE_NEWNS) {nsset->fs = me->fs;} else if (flags & CLONE_NEWNS) {nsset->fs = copy_fs_struct(me->fs);if (!nsset->fs)goto out;}nsset->flags = flags;return 0;out:put_nsset(nsset);return -ENOMEM;}static inline int validate_ns(struct nsset *nsset, struct ns_common *ns){return ns->ops->install(nsset, ns);}/** This is the inverse operation to unshare().* Ordering is equivalent to the standard ordering used everywhere else* during unshare and process creation. The switch to the new set of* namespaces occurs at the point of no return after installation of* all requested namespaces was successful in commit_nsset().*/static int validate_nsset(struct nsset *nsset, struct pid *pid){int ret = 0;unsigned flags = nsset->flags;struct user_namespace *user_ns = NULL;struct pid_namespace *pid_ns = NULL;struct nsproxy *nsp;struct task_struct *tsk;/* Take a "snapshot" of the target task's namespaces. */rcu_read_lock();tsk = pid_task(pid, PIDTYPE_PID);if (!tsk) {rcu_read_unlock();return -ESRCH;}if (!ptrace_may_access(tsk, PTRACE_MODE_READ_REALCREDS)) {rcu_read_unlock();return -EPERM;}task_lock(tsk);nsp = tsk->nsproxy;if (nsp)get_nsproxy(nsp);task_unlock(tsk);if (!nsp) {rcu_read_unlock();return -ESRCH;}#ifdef CONFIG_PID_NSif (flags & CLONE_NEWPID) {pid_ns = task_active_pid_ns(tsk);if (unlikely(!pid_ns)) {rcu_read_unlock();ret = -ESRCH;goto out;}get_pid_ns(pid_ns);}#endif#ifdef CONFIG_USER_NSif (flags & CLONE_NEWUSER)user_ns = get_user_ns(__task_cred(tsk)->user_ns);#endifrcu_read_unlock();/** Install requested namespaces. The caller will have* verified earlier that the requested namespaces are* supported on this kernel. We don't report errors here* if a namespace is requested that isn't supported.*/#ifdef CONFIG_USER_NSif (flags & CLONE_NEWUSER) {ret = validate_ns(nsset, &user_ns->ns);if (ret)goto out;}#endifif (flags & CLONE_NEWNS) {ret = validate_ns(nsset, from_mnt_ns(nsp->mnt_ns));if (ret)goto out;}#ifdef CONFIG_UTS_NSif (flags & CLONE_NEWUTS) {ret = validate_ns(nsset, &nsp->uts_ns->ns);if (ret)goto out;}#endif#ifdef CONFIG_IPC_NSif (flags & CLONE_NEWIPC) {ret = validate_ns(nsset, &nsp->ipc_ns->ns);if (ret)goto out;}#endif#ifdef CONFIG_PID_NSif (flags & CLONE_NEWPID) {ret = validate_ns(nsset, &pid_ns->ns);if (ret)goto out;}#endif#ifdef CONFIG_CGROUPSif (flags & CLONE_NEWCGROUP) {ret = validate_ns(nsset, &nsp->cgroup_ns->ns);if (ret)goto out;}#endif#ifdef CONFIG_NET_NSif (flags & CLONE_NEWNET) {ret = validate_ns(nsset, &nsp->net_ns->ns);if (ret)goto out;}#endif#ifdef CONFIG_TIME_NSif (flags & CLONE_NEWTIME) {ret = validate_ns(nsset, &nsp->time_ns->ns);if (ret)goto out;}#endifout:if (pid_ns)put_pid_ns(pid_ns);if (nsp)put_nsproxy(nsp);put_user_ns(user_ns);return ret;}/** This is the point of no return. There are just a few namespaces* that do some actual work here and it's sufficiently minimal that* a separate ns_common operation seems unnecessary for now.* Unshare is doing the same thing. If we'll end up needing to do* more in a given namespace or a helper here is ultimately not* exported anymore a simple commit handler for each namespace* should be added to ns_common.*/static void commit_nsset(struct nsset *nsset){unsigned flags = nsset->flags;struct task_struct *me = current;#ifdef CONFIG_USER_NSif (flags & CLONE_NEWUSER) {/* transfer ownership */commit_creds(nsset_cred(nsset));nsset->cred = NULL;}#endif/* We only need to commit if we have used a temporary fs_struct. */if ((flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) {set_fs_root(me->fs, &nsset->fs->root);set_fs_pwd(me->fs, &nsset->fs->pwd);}#ifdef CONFIG_IPC_NSif (flags & CLONE_NEWIPC)exit_sem(me);#endif#ifdef CONFIG_TIME_NSif (flags & CLONE_NEWTIME)timens_commit(me, nsset->nsproxy->time_ns);#endif/* transfer ownership */switch_task_namespaces(me, nsset->nsproxy);nsset->nsproxy = NULL;}SYSCALL_DEFINE2(setns, int, fd, int, flags){CLASS(fd, f)(fd);struct ns_common *ns = NULL;struct nsset nsset = {};int err = 0;if (fd_empty(f))return -EBADF;if (proc_ns_file(fd_file(f))) {ns = get_proc_ns(file_inode(fd_file(f)));if (flags && (ns->ops->type != flags))err = -EINVAL;flags = ns->ops->type;} else if (!IS_ERR(pidfd_pid(fd_file(f)))) {err = check_setns_flags(flags);} else {err = -EINVAL;}if (err)goto out;err = prepare_nsset(flags, &nsset);if (err)goto out;if (proc_ns_file(fd_file(f)))err = validate_ns(&nsset, ns);elseerr = validate_nsset(&nsset, pidfd_pid(fd_file(f)));if (!err) {commit_nsset(&nsset);perf_event_namespaces(current);}put_nsset(&nsset);out:return err;}int __init nsproxy_cache_init(void){nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC|SLAB_ACCOUNT);return 0;}
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