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Diffstat (limited to '')
| -rw-r--r-- | kernel/utsname.c | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/kernel/utsname.c b/kernel/utsname.c new file mode 100644 index 0000000000..b1ac3ca870 --- /dev/null +++ b/kernel/utsname.c @@ -0,0 +1,177 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2004 IBM Corporation + * + * Author: Serge Hallyn <serue@us.ibm.com> + */ + +#include <linux/export.h> +#include <linux/uts.h> +#include <linux/utsname.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/cred.h> +#include <linux/user_namespace.h> +#include <linux/proc_ns.h> +#include <linux/sched/task.h> + +static struct kmem_cache *uts_ns_cache __ro_after_init; + +static struct ucounts *inc_uts_namespaces(struct user_namespace *ns) +{ + return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES); +} + +static void dec_uts_namespaces(struct ucounts *ucounts) +{ + dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES); +} + +static struct uts_namespace *create_uts_ns(void) +{ + struct uts_namespace *uts_ns; + + uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL); + if (uts_ns) + refcount_set(&uts_ns->ns.count, 1); + return uts_ns; +} + +/* + * Clone a new ns copying an original utsname, setting refcount to 1 + * @old_ns: namespace to clone + * Return ERR_PTR(-ENOMEM) on error (failure to allocate), new ns otherwise + */ +static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns, + struct uts_namespace *old_ns) +{ + struct uts_namespace *ns; + struct ucounts *ucounts; + int err; + + err = -ENOSPC; + ucounts = inc_uts_namespaces(user_ns); + if (!ucounts) + goto fail; + + err = -ENOMEM; + ns = create_uts_ns(); + if (!ns) + goto fail_dec; + + err = ns_alloc_inum(&ns->ns); + if (err) + goto fail_free; + + ns->ucounts = ucounts; + ns->ns.ops = &utsns_operations; + + down_read(&uts_sem); + memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); + ns->user_ns = get_user_ns(user_ns); + up_read(&uts_sem); + return ns; + +fail_free: + kmem_cache_free(uts_ns_cache, ns); +fail_dec: + dec_uts_namespaces(ucounts); +fail: + return ERR_PTR(err); +} + +/* + * Copy task tsk's utsname namespace, or clone it if flags + * specifies CLONE_NEWUTS. In latter case, changes to the + * utsname of this process won't be seen by parent, and vice + * versa. + */ +struct uts_namespace *copy_utsname(unsigned long flags, + struct user_namespace *user_ns, struct uts_namespace *old_ns) +{ + struct uts_namespace *new_ns; + + BUG_ON(!old_ns); + get_uts_ns(old_ns); + + if (!(flags & CLONE_NEWUTS)) + return old_ns; + + new_ns = clone_uts_ns(user_ns, old_ns); + + put_uts_ns(old_ns); + return new_ns; +} + +void free_uts_ns(struct uts_namespace *ns) +{ + dec_uts_namespaces(ns->ucounts); + put_user_ns(ns->user_ns); + ns_free_inum(&ns->ns); + kmem_cache_free(uts_ns_cache, ns); +} + +static inline struct uts_namespace *to_uts_ns(struct ns_common *ns) +{ + return container_of(ns, struct uts_namespace, ns); +} + +static struct ns_common *utsns_get(struct task_struct *task) +{ + struct uts_namespace *ns = NULL; + struct nsproxy *nsproxy; + + task_lock(task); + nsproxy = task->nsproxy; + if (nsproxy) { + ns = nsproxy->uts_ns; + get_uts_ns(ns); + } + task_unlock(task); + + return ns ? &ns->ns : NULL; +} + +static void utsns_put(struct ns_common *ns) +{ + put_uts_ns(to_uts_ns(ns)); +} + +static int utsns_install(struct nsset *nsset, struct ns_common *new) +{ + struct nsproxy *nsproxy = nsset->nsproxy; + struct uts_namespace *ns = to_uts_ns(new); + + if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) || + !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN)) + return -EPERM; + + get_uts_ns(ns); + put_uts_ns(nsproxy->uts_ns); + nsproxy->uts_ns = ns; + return 0; +} + +static struct user_namespace *utsns_owner(struct ns_common *ns) +{ + return to_uts_ns(ns)->user_ns; +} + +const struct proc_ns_operations utsns_operations = { + .name = "uts", + .type = CLONE_NEWUTS, + .get = utsns_get, + .put = utsns_put, + .install = utsns_install, + .owner = utsns_owner, +}; + +void __init uts_ns_init(void) +{ + uts_ns_cache = kmem_cache_create_usercopy( + "uts_namespace", sizeof(struct uts_namespace), 0, + SLAB_PANIC|SLAB_ACCOUNT, + offsetof(struct uts_namespace, name), + sizeof_field(struct uts_namespace, name), + NULL); +} |