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1391 lines
35 KiB
1391 lines
35 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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#include <linux/export.h> |
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#include <linux/nsproxy.h> |
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#include <linux/slab.h> |
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#include <linux/sched/signal.h> |
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#include <linux/user_namespace.h> |
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#include <linux/proc_ns.h> |
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#include <linux/highuid.h> |
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#include <linux/cred.h> |
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#include <linux/securebits.h> |
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#include <linux/keyctl.h> |
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#include <linux/key-type.h> |
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#include <keys/user-type.h> |
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#include <linux/seq_file.h> |
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#include <linux/fs.h> |
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#include <linux/uaccess.h> |
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#include <linux/ctype.h> |
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#include <linux/projid.h> |
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#include <linux/fs_struct.h> |
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#include <linux/bsearch.h> |
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#include <linux/sort.h> |
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static struct kmem_cache *user_ns_cachep __read_mostly; |
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static DEFINE_MUTEX(userns_state_mutex); |
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static bool new_idmap_permitted(const struct file *file, |
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struct user_namespace *ns, int cap_setid, |
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struct uid_gid_map *map); |
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static void free_user_ns(struct work_struct *work); |
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static struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid) |
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{ |
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return inc_ucount(ns, uid, UCOUNT_USER_NAMESPACES); |
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} |
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|
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static void dec_user_namespaces(struct ucounts *ucounts) |
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{ |
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return dec_ucount(ucounts, UCOUNT_USER_NAMESPACES); |
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} |
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static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns) |
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{ |
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/* Start with the same capabilities as init but useless for doing |
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* anything as the capabilities are bound to the new user namespace. |
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*/ |
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cred->securebits = SECUREBITS_DEFAULT; |
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cred->cap_inheritable = CAP_EMPTY_SET; |
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cred->cap_permitted = CAP_FULL_SET; |
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cred->cap_effective = CAP_FULL_SET; |
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cred->cap_ambient = CAP_EMPTY_SET; |
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cred->cap_bset = CAP_FULL_SET; |
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#ifdef CONFIG_KEYS |
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key_put(cred->request_key_auth); |
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cred->request_key_auth = NULL; |
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#endif |
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/* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */ |
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cred->user_ns = user_ns; |
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} |
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|
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/* |
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* Create a new user namespace, deriving the creator from the user in the |
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* passed credentials, and replacing that user with the new root user for the |
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* new namespace. |
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* |
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* This is called by copy_creds(), which will finish setting the target task's |
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* credentials. |
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*/ |
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int create_user_ns(struct cred *new) |
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{ |
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struct user_namespace *ns, *parent_ns = new->user_ns; |
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kuid_t owner = new->euid; |
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kgid_t group = new->egid; |
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struct ucounts *ucounts; |
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int ret, i; |
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ret = -ENOSPC; |
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if (parent_ns->level > 32) |
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goto fail; |
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ucounts = inc_user_namespaces(parent_ns, owner); |
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if (!ucounts) |
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goto fail; |
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/* |
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* Verify that we can not violate the policy of which files |
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* may be accessed that is specified by the root directory, |
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* by verifying that the root directory is at the root of the |
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* mount namespace which allows all files to be accessed. |
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*/ |
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ret = -EPERM; |
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if (current_chrooted()) |
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goto fail_dec; |
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/* The creator needs a mapping in the parent user namespace |
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* or else we won't be able to reasonably tell userspace who |
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* created a user_namespace. |
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*/ |
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ret = -EPERM; |
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if (!kuid_has_mapping(parent_ns, owner) || |
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!kgid_has_mapping(parent_ns, group)) |
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goto fail_dec; |
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ret = -ENOMEM; |
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ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL); |
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if (!ns) |
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goto fail_dec; |
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ns->parent_could_setfcap = cap_raised(new->cap_effective, CAP_SETFCAP); |
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ret = ns_alloc_inum(&ns->ns); |
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if (ret) |
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goto fail_free; |
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ns->ns.ops = &userns_operations; |
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refcount_set(&ns->ns.count, 1); |
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/* Leave the new->user_ns reference with the new user namespace. */ |
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ns->parent = parent_ns; |
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ns->level = parent_ns->level + 1; |
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ns->owner = owner; |
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ns->group = group; |
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INIT_WORK(&ns->work, free_user_ns); |
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for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++) { |
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ns->ucount_max[i] = INT_MAX; |
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} |
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set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC)); |
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set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_MSGQUEUE, rlimit(RLIMIT_MSGQUEUE)); |
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set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_SIGPENDING, rlimit(RLIMIT_SIGPENDING)); |
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set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_MEMLOCK, rlimit(RLIMIT_MEMLOCK)); |
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ns->ucounts = ucounts; |
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/* Inherit USERNS_SETGROUPS_ALLOWED from our parent */ |
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mutex_lock(&userns_state_mutex); |
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ns->flags = parent_ns->flags; |
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mutex_unlock(&userns_state_mutex); |
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#ifdef CONFIG_KEYS |
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INIT_LIST_HEAD(&ns->keyring_name_list); |
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init_rwsem(&ns->keyring_sem); |
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#endif |
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ret = -ENOMEM; |
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if (!setup_userns_sysctls(ns)) |
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goto fail_keyring; |
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set_cred_user_ns(new, ns); |
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return 0; |
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fail_keyring: |
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#ifdef CONFIG_PERSISTENT_KEYRINGS |
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key_put(ns->persistent_keyring_register); |
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#endif |
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ns_free_inum(&ns->ns); |
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fail_free: |
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kmem_cache_free(user_ns_cachep, ns); |
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fail_dec: |
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dec_user_namespaces(ucounts); |
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fail: |
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return ret; |
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} |
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int unshare_userns(unsigned long unshare_flags, struct cred **new_cred) |
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{ |
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struct cred *cred; |
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int err = -ENOMEM; |
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if (!(unshare_flags & CLONE_NEWUSER)) |
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return 0; |
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cred = prepare_creds(); |
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if (cred) { |
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err = create_user_ns(cred); |
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if (err) |
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put_cred(cred); |
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else |
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*new_cred = cred; |
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} |
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return err; |
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} |
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static void free_user_ns(struct work_struct *work) |
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{ |
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struct user_namespace *parent, *ns = |
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container_of(work, struct user_namespace, work); |
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do { |
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struct ucounts *ucounts = ns->ucounts; |
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parent = ns->parent; |
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if (ns->gid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
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kfree(ns->gid_map.forward); |
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kfree(ns->gid_map.reverse); |
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} |
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if (ns->uid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
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kfree(ns->uid_map.forward); |
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kfree(ns->uid_map.reverse); |
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} |
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if (ns->projid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
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kfree(ns->projid_map.forward); |
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kfree(ns->projid_map.reverse); |
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} |
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retire_userns_sysctls(ns); |
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key_free_user_ns(ns); |
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ns_free_inum(&ns->ns); |
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kmem_cache_free(user_ns_cachep, ns); |
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dec_user_namespaces(ucounts); |
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ns = parent; |
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} while (refcount_dec_and_test(&parent->ns.count)); |
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} |
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void __put_user_ns(struct user_namespace *ns) |
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{ |
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schedule_work(&ns->work); |
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} |
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EXPORT_SYMBOL(__put_user_ns); |
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/** |
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* idmap_key struct holds the information necessary to find an idmapping in a |
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* sorted idmap array. It is passed to cmp_map_id() as first argument. |
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*/ |
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struct idmap_key { |
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bool map_up; /* true -> id from kid; false -> kid from id */ |
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u32 id; /* id to find */ |
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u32 count; /* == 0 unless used with map_id_range_down() */ |
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}; |
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/** |
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* cmp_map_id - Function to be passed to bsearch() to find the requested |
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* idmapping. Expects struct idmap_key to be passed via @k. |
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*/ |
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static int cmp_map_id(const void *k, const void *e) |
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{ |
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u32 first, last, id2; |
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const struct idmap_key *key = k; |
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const struct uid_gid_extent *el = e; |
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id2 = key->id + key->count - 1; |
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/* handle map_id_{down,up}() */ |
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if (key->map_up) |
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first = el->lower_first; |
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else |
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first = el->first; |
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last = first + el->count - 1; |
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if (key->id >= first && key->id <= last && |
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(id2 >= first && id2 <= last)) |
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return 0; |
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if (key->id < first || id2 < first) |
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return -1; |
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return 1; |
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} |
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/** |
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* map_id_range_down_max - Find idmap via binary search in ordered idmap array. |
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* Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. |
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*/ |
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static struct uid_gid_extent * |
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map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) |
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{ |
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struct idmap_key key; |
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key.map_up = false; |
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key.count = count; |
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key.id = id; |
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return bsearch(&key, map->forward, extents, |
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sizeof(struct uid_gid_extent), cmp_map_id); |
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} |
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/** |
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* map_id_range_down_base - Find idmap via binary search in static extent array. |
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* Can only be called if number of mappings is equal or less than |
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* UID_GID_MAP_MAX_BASE_EXTENTS. |
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*/ |
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static struct uid_gid_extent * |
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map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) |
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{ |
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unsigned idx; |
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u32 first, last, id2; |
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id2 = id + count - 1; |
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/* Find the matching extent */ |
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for (idx = 0; idx < extents; idx++) { |
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first = map->extent[idx].first; |
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last = first + map->extent[idx].count - 1; |
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if (id >= first && id <= last && |
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(id2 >= first && id2 <= last)) |
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return &map->extent[idx]; |
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} |
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return NULL; |
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} |
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static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count) |
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{ |
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struct uid_gid_extent *extent; |
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unsigned extents = map->nr_extents; |
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smp_rmb(); |
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if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
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extent = map_id_range_down_base(extents, map, id, count); |
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else |
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extent = map_id_range_down_max(extents, map, id, count); |
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/* Map the id or note failure */ |
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if (extent) |
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id = (id - extent->first) + extent->lower_first; |
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else |
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id = (u32) -1; |
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return id; |
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} |
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static u32 map_id_down(struct uid_gid_map *map, u32 id) |
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{ |
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return map_id_range_down(map, id, 1); |
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} |
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/** |
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* map_id_up_base - Find idmap via binary search in static extent array. |
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* Can only be called if number of mappings is equal or less than |
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* UID_GID_MAP_MAX_BASE_EXTENTS. |
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*/ |
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static struct uid_gid_extent * |
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map_id_up_base(unsigned extents, struct uid_gid_map *map, u32 id) |
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{ |
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unsigned idx; |
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u32 first, last; |
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/* Find the matching extent */ |
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for (idx = 0; idx < extents; idx++) { |
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first = map->extent[idx].lower_first; |
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last = first + map->extent[idx].count - 1; |
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if (id >= first && id <= last) |
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return &map->extent[idx]; |
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} |
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return NULL; |
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} |
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/** |
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* map_id_up_max - Find idmap via binary search in ordered idmap array. |
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* Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. |
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*/ |
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static struct uid_gid_extent * |
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map_id_up_max(unsigned extents, struct uid_gid_map *map, u32 id) |
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{ |
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struct idmap_key key; |
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key.map_up = true; |
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key.count = 1; |
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key.id = id; |
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return bsearch(&key, map->reverse, extents, |
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sizeof(struct uid_gid_extent), cmp_map_id); |
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} |
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static u32 map_id_up(struct uid_gid_map *map, u32 id) |
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{ |
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struct uid_gid_extent *extent; |
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unsigned extents = map->nr_extents; |
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smp_rmb(); |
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if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
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extent = map_id_up_base(extents, map, id); |
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else |
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extent = map_id_up_max(extents, map, id); |
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/* Map the id or note failure */ |
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if (extent) |
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id = (id - extent->lower_first) + extent->first; |
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else |
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id = (u32) -1; |
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return id; |
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} |
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/** |
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* make_kuid - Map a user-namespace uid pair into a kuid. |
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* @ns: User namespace that the uid is in |
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* @uid: User identifier |
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* |
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* Maps a user-namespace uid pair into a kernel internal kuid, |
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* and returns that kuid. |
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* |
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* When there is no mapping defined for the user-namespace uid |
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* pair INVALID_UID is returned. Callers are expected to test |
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* for and handle INVALID_UID being returned. INVALID_UID |
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* may be tested for using uid_valid(). |
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*/ |
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kuid_t make_kuid(struct user_namespace *ns, uid_t uid) |
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{ |
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/* Map the uid to a global kernel uid */ |
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return KUIDT_INIT(map_id_down(&ns->uid_map, uid)); |
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} |
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EXPORT_SYMBOL(make_kuid); |
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/** |
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* from_kuid - Create a uid from a kuid user-namespace pair. |
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* @targ: The user namespace we want a uid in. |
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* @kuid: The kernel internal uid to start with. |
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* |
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* Map @kuid into the user-namespace specified by @targ and |
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* return the resulting uid. |
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* |
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* There is always a mapping into the initial user_namespace. |
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* |
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* If @kuid has no mapping in @targ (uid_t)-1 is returned. |
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*/ |
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uid_t from_kuid(struct user_namespace *targ, kuid_t kuid) |
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{ |
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/* Map the uid from a global kernel uid */ |
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return map_id_up(&targ->uid_map, __kuid_val(kuid)); |
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} |
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EXPORT_SYMBOL(from_kuid); |
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/** |
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* from_kuid_munged - Create a uid from a kuid user-namespace pair. |
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* @targ: The user namespace we want a uid in. |
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* @kuid: The kernel internal uid to start with. |
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* |
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* Map @kuid into the user-namespace specified by @targ and |
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* return the resulting uid. |
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* |
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* There is always a mapping into the initial user_namespace. |
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* |
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* Unlike from_kuid from_kuid_munged never fails and always |
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* returns a valid uid. This makes from_kuid_munged appropriate |
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* for use in syscalls like stat and getuid where failing the |
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* system call and failing to provide a valid uid are not an |
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* options. |
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* |
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* If @kuid has no mapping in @targ overflowuid is returned. |
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*/ |
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uid_t from_kuid_munged(struct user_namespace *targ, kuid_t kuid) |
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{ |
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uid_t uid; |
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uid = from_kuid(targ, kuid); |
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if (uid == (uid_t) -1) |
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uid = overflowuid; |
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return uid; |
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} |
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EXPORT_SYMBOL(from_kuid_munged); |
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|
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/** |
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* make_kgid - Map a user-namespace gid pair into a kgid. |
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* @ns: User namespace that the gid is in |
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* @gid: group identifier |
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* |
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* Maps a user-namespace gid pair into a kernel internal kgid, |
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* and returns that kgid. |
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* |
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* When there is no mapping defined for the user-namespace gid |
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* pair INVALID_GID is returned. Callers are expected to test |
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* for and handle INVALID_GID being returned. INVALID_GID may be |
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* tested for using gid_valid(). |
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*/ |
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kgid_t make_kgid(struct user_namespace *ns, gid_t gid) |
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{ |
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/* Map the gid to a global kernel gid */ |
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return KGIDT_INIT(map_id_down(&ns->gid_map, gid)); |
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} |
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EXPORT_SYMBOL(make_kgid); |
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|
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/** |
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* from_kgid - Create a gid from a kgid user-namespace pair. |
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* @targ: The user namespace we want a gid in. |
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* @kgid: The kernel internal gid to start with. |
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* |
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* Map @kgid into the user-namespace specified by @targ and |
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* return the resulting gid. |
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* |
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* There is always a mapping into the initial user_namespace. |
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* |
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* If @kgid has no mapping in @targ (gid_t)-1 is returned. |
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*/ |
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gid_t from_kgid(struct user_namespace *targ, kgid_t kgid) |
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{ |
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/* Map the gid from a global kernel gid */ |
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return map_id_up(&targ->gid_map, __kgid_val(kgid)); |
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} |
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EXPORT_SYMBOL(from_kgid); |
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|
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/** |
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* from_kgid_munged - Create a gid from a kgid user-namespace pair. |
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* @targ: The user namespace we want a gid in. |
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* @kgid: The kernel internal gid to start with. |
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* |
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* Map @kgid into the user-namespace specified by @targ and |
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* return the resulting gid. |
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* |
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* There is always a mapping into the initial user_namespace. |
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* |
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* Unlike from_kgid from_kgid_munged never fails and always |
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* returns a valid gid. This makes from_kgid_munged appropriate |
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* for use in syscalls like stat and getgid where failing the |
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* system call and failing to provide a valid gid are not options. |
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* |
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* If @kgid has no mapping in @targ overflowgid is returned. |
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*/ |
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gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid) |
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{ |
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gid_t gid; |
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gid = from_kgid(targ, kgid); |
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|
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if (gid == (gid_t) -1) |
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gid = overflowgid; |
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return gid; |
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} |
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EXPORT_SYMBOL(from_kgid_munged); |
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|
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/** |
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* make_kprojid - Map a user-namespace projid pair into a kprojid. |
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* @ns: User namespace that the projid is in |
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* @projid: Project identifier |
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* |
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* Maps a user-namespace uid pair into a kernel internal kuid, |
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* and returns that kuid. |
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* |
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* When there is no mapping defined for the user-namespace projid |
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* pair INVALID_PROJID is returned. Callers are expected to test |
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* for and handle INVALID_PROJID being returned. INVALID_PROJID |
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* may be tested for using projid_valid(). |
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*/ |
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kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid) |
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{ |
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/* Map the uid to a global kernel uid */ |
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return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid)); |
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} |
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EXPORT_SYMBOL(make_kprojid); |
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|
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/** |
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* from_kprojid - Create a projid from a kprojid user-namespace pair. |
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* @targ: The user namespace we want a projid in. |
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* @kprojid: The kernel internal project identifier to start with. |
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* |
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* Map @kprojid into the user-namespace specified by @targ and |
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* return the resulting projid. |
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* |
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* There is always a mapping into the initial user_namespace. |
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* |
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* If @kprojid has no mapping in @targ (projid_t)-1 is returned. |
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*/ |
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projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid) |
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{ |
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/* Map the uid from a global kernel uid */ |
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return map_id_up(&targ->projid_map, __kprojid_val(kprojid)); |
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} |
|
EXPORT_SYMBOL(from_kprojid); |
|
|
|
/** |
|
* from_kprojid_munged - Create a projiid from a kprojid user-namespace pair. |
|
* @targ: The user namespace we want a projid in. |
|
* @kprojid: The kernel internal projid to start with. |
|
* |
|
* Map @kprojid into the user-namespace specified by @targ and |
|
* return the resulting projid. |
|
* |
|
* There is always a mapping into the initial user_namespace. |
|
* |
|
* Unlike from_kprojid from_kprojid_munged never fails and always |
|
* returns a valid projid. This makes from_kprojid_munged |
|
* appropriate for use in syscalls like stat and where |
|
* failing the system call and failing to provide a valid projid are |
|
* not an options. |
|
* |
|
* If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned. |
|
*/ |
|
projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid) |
|
{ |
|
projid_t projid; |
|
projid = from_kprojid(targ, kprojid); |
|
|
|
if (projid == (projid_t) -1) |
|
projid = OVERFLOW_PROJID; |
|
return projid; |
|
} |
|
EXPORT_SYMBOL(from_kprojid_munged); |
|
|
|
|
|
static int uid_m_show(struct seq_file *seq, void *v) |
|
{ |
|
struct user_namespace *ns = seq->private; |
|
struct uid_gid_extent *extent = v; |
|
struct user_namespace *lower_ns; |
|
uid_t lower; |
|
|
|
lower_ns = seq_user_ns(seq); |
|
if ((lower_ns == ns) && lower_ns->parent) |
|
lower_ns = lower_ns->parent; |
|
|
|
lower = from_kuid(lower_ns, KUIDT_INIT(extent->lower_first)); |
|
|
|
seq_printf(seq, "%10u %10u %10u\n", |
|
extent->first, |
|
lower, |
|
extent->count); |
|
|
|
return 0; |
|
} |
|
|
|
static int gid_m_show(struct seq_file *seq, void *v) |
|
{ |
|
struct user_namespace *ns = seq->private; |
|
struct uid_gid_extent *extent = v; |
|
struct user_namespace *lower_ns; |
|
gid_t lower; |
|
|
|
lower_ns = seq_user_ns(seq); |
|
if ((lower_ns == ns) && lower_ns->parent) |
|
lower_ns = lower_ns->parent; |
|
|
|
lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first)); |
|
|
|
seq_printf(seq, "%10u %10u %10u\n", |
|
extent->first, |
|
lower, |
|
extent->count); |
|
|
|
return 0; |
|
} |
|
|
|
static int projid_m_show(struct seq_file *seq, void *v) |
|
{ |
|
struct user_namespace *ns = seq->private; |
|
struct uid_gid_extent *extent = v; |
|
struct user_namespace *lower_ns; |
|
projid_t lower; |
|
|
|
lower_ns = seq_user_ns(seq); |
|
if ((lower_ns == ns) && lower_ns->parent) |
|
lower_ns = lower_ns->parent; |
|
|
|
lower = from_kprojid(lower_ns, KPROJIDT_INIT(extent->lower_first)); |
|
|
|
seq_printf(seq, "%10u %10u %10u\n", |
|
extent->first, |
|
lower, |
|
extent->count); |
|
|
|
return 0; |
|
} |
|
|
|
static void *m_start(struct seq_file *seq, loff_t *ppos, |
|
struct uid_gid_map *map) |
|
{ |
|
loff_t pos = *ppos; |
|
unsigned extents = map->nr_extents; |
|
smp_rmb(); |
|
|
|
if (pos >= extents) |
|
return NULL; |
|
|
|
if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
|
return &map->extent[pos]; |
|
|
|
return &map->forward[pos]; |
|
} |
|
|
|
static void *uid_m_start(struct seq_file *seq, loff_t *ppos) |
|
{ |
|
struct user_namespace *ns = seq->private; |
|
|
|
return m_start(seq, ppos, &ns->uid_map); |
|
} |
|
|
|
static void *gid_m_start(struct seq_file *seq, loff_t *ppos) |
|
{ |
|
struct user_namespace *ns = seq->private; |
|
|
|
return m_start(seq, ppos, &ns->gid_map); |
|
} |
|
|
|
static void *projid_m_start(struct seq_file *seq, loff_t *ppos) |
|
{ |
|
struct user_namespace *ns = seq->private; |
|
|
|
return m_start(seq, ppos, &ns->projid_map); |
|
} |
|
|
|
static void *m_next(struct seq_file *seq, void *v, loff_t *pos) |
|
{ |
|
(*pos)++; |
|
return seq->op->start(seq, pos); |
|
} |
|
|
|
static void m_stop(struct seq_file *seq, void *v) |
|
{ |
|
return; |
|
} |
|
|
|
const struct seq_operations proc_uid_seq_operations = { |
|
.start = uid_m_start, |
|
.stop = m_stop, |
|
.next = m_next, |
|
.show = uid_m_show, |
|
}; |
|
|
|
const struct seq_operations proc_gid_seq_operations = { |
|
.start = gid_m_start, |
|
.stop = m_stop, |
|
.next = m_next, |
|
.show = gid_m_show, |
|
}; |
|
|
|
const struct seq_operations proc_projid_seq_operations = { |
|
.start = projid_m_start, |
|
.stop = m_stop, |
|
.next = m_next, |
|
.show = projid_m_show, |
|
}; |
|
|
|
static bool mappings_overlap(struct uid_gid_map *new_map, |
|
struct uid_gid_extent *extent) |
|
{ |
|
u32 upper_first, lower_first, upper_last, lower_last; |
|
unsigned idx; |
|
|
|
upper_first = extent->first; |
|
lower_first = extent->lower_first; |
|
upper_last = upper_first + extent->count - 1; |
|
lower_last = lower_first + extent->count - 1; |
|
|
|
for (idx = 0; idx < new_map->nr_extents; idx++) { |
|
u32 prev_upper_first, prev_lower_first; |
|
u32 prev_upper_last, prev_lower_last; |
|
struct uid_gid_extent *prev; |
|
|
|
if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
|
prev = &new_map->extent[idx]; |
|
else |
|
prev = &new_map->forward[idx]; |
|
|
|
prev_upper_first = prev->first; |
|
prev_lower_first = prev->lower_first; |
|
prev_upper_last = prev_upper_first + prev->count - 1; |
|
prev_lower_last = prev_lower_first + prev->count - 1; |
|
|
|
/* Does the upper range intersect a previous extent? */ |
|
if ((prev_upper_first <= upper_last) && |
|
(prev_upper_last >= upper_first)) |
|
return true; |
|
|
|
/* Does the lower range intersect a previous extent? */ |
|
if ((prev_lower_first <= lower_last) && |
|
(prev_lower_last >= lower_first)) |
|
return true; |
|
} |
|
return false; |
|
} |
|
|
|
/** |
|
* insert_extent - Safely insert a new idmap extent into struct uid_gid_map. |
|
* Takes care to allocate a 4K block of memory if the number of mappings exceeds |
|
* UID_GID_MAP_MAX_BASE_EXTENTS. |
|
*/ |
|
static int insert_extent(struct uid_gid_map *map, struct uid_gid_extent *extent) |
|
{ |
|
struct uid_gid_extent *dest; |
|
|
|
if (map->nr_extents == UID_GID_MAP_MAX_BASE_EXTENTS) { |
|
struct uid_gid_extent *forward; |
|
|
|
/* Allocate memory for 340 mappings. */ |
|
forward = kmalloc_array(UID_GID_MAP_MAX_EXTENTS, |
|
sizeof(struct uid_gid_extent), |
|
GFP_KERNEL); |
|
if (!forward) |
|
return -ENOMEM; |
|
|
|
/* Copy over memory. Only set up memory for the forward pointer. |
|
* Defer the memory setup for the reverse pointer. |
|
*/ |
|
memcpy(forward, map->extent, |
|
map->nr_extents * sizeof(map->extent[0])); |
|
|
|
map->forward = forward; |
|
map->reverse = NULL; |
|
} |
|
|
|
if (map->nr_extents < UID_GID_MAP_MAX_BASE_EXTENTS) |
|
dest = &map->extent[map->nr_extents]; |
|
else |
|
dest = &map->forward[map->nr_extents]; |
|
|
|
*dest = *extent; |
|
map->nr_extents++; |
|
return 0; |
|
} |
|
|
|
/* cmp function to sort() forward mappings */ |
|
static int cmp_extents_forward(const void *a, const void *b) |
|
{ |
|
const struct uid_gid_extent *e1 = a; |
|
const struct uid_gid_extent *e2 = b; |
|
|
|
if (e1->first < e2->first) |
|
return -1; |
|
|
|
if (e1->first > e2->first) |
|
return 1; |
|
|
|
return 0; |
|
} |
|
|
|
/* cmp function to sort() reverse mappings */ |
|
static int cmp_extents_reverse(const void *a, const void *b) |
|
{ |
|
const struct uid_gid_extent *e1 = a; |
|
const struct uid_gid_extent *e2 = b; |
|
|
|
if (e1->lower_first < e2->lower_first) |
|
return -1; |
|
|
|
if (e1->lower_first > e2->lower_first) |
|
return 1; |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* sort_idmaps - Sorts an array of idmap entries. |
|
* Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. |
|
*/ |
|
static int sort_idmaps(struct uid_gid_map *map) |
|
{ |
|
if (map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
|
return 0; |
|
|
|
/* Sort forward array. */ |
|
sort(map->forward, map->nr_extents, sizeof(struct uid_gid_extent), |
|
cmp_extents_forward, NULL); |
|
|
|
/* Only copy the memory from forward we actually need. */ |
|
map->reverse = kmemdup(map->forward, |
|
map->nr_extents * sizeof(struct uid_gid_extent), |
|
GFP_KERNEL); |
|
if (!map->reverse) |
|
return -ENOMEM; |
|
|
|
/* Sort reverse array. */ |
|
sort(map->reverse, map->nr_extents, sizeof(struct uid_gid_extent), |
|
cmp_extents_reverse, NULL); |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* verify_root_map() - check the uid 0 mapping |
|
* @file: idmapping file |
|
* @map_ns: user namespace of the target process |
|
* @new_map: requested idmap |
|
* |
|
* If a process requests mapping parent uid 0 into the new ns, verify that the |
|
* process writing the map had the CAP_SETFCAP capability as the target process |
|
* will be able to write fscaps that are valid in ancestor user namespaces. |
|
* |
|
* Return: true if the mapping is allowed, false if not. |
|
*/ |
|
static bool verify_root_map(const struct file *file, |
|
struct user_namespace *map_ns, |
|
struct uid_gid_map *new_map) |
|
{ |
|
int idx; |
|
const struct user_namespace *file_ns = file->f_cred->user_ns; |
|
struct uid_gid_extent *extent0 = NULL; |
|
|
|
for (idx = 0; idx < new_map->nr_extents; idx++) { |
|
if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
|
extent0 = &new_map->extent[idx]; |
|
else |
|
extent0 = &new_map->forward[idx]; |
|
if (extent0->lower_first == 0) |
|
break; |
|
|
|
extent0 = NULL; |
|
} |
|
|
|
if (!extent0) |
|
return true; |
|
|
|
if (map_ns == file_ns) { |
|
/* The process unshared its ns and is writing to its own |
|
* /proc/self/uid_map. User already has full capabilites in |
|
* the new namespace. Verify that the parent had CAP_SETFCAP |
|
* when it unshared. |
|
* */ |
|
if (!file_ns->parent_could_setfcap) |
|
return false; |
|
} else { |
|
/* Process p1 is writing to uid_map of p2, who is in a child |
|
* user namespace to p1's. Verify that the opener of the map |
|
* file has CAP_SETFCAP against the parent of the new map |
|
* namespace */ |
|
if (!file_ns_capable(file, map_ns->parent, CAP_SETFCAP)) |
|
return false; |
|
} |
|
|
|
return true; |
|
} |
|
|
|
static ssize_t map_write(struct file *file, const char __user *buf, |
|
size_t count, loff_t *ppos, |
|
int cap_setid, |
|
struct uid_gid_map *map, |
|
struct uid_gid_map *parent_map) |
|
{ |
|
struct seq_file *seq = file->private_data; |
|
struct user_namespace *map_ns = seq->private; |
|
struct uid_gid_map new_map; |
|
unsigned idx; |
|
struct uid_gid_extent extent; |
|
char *kbuf = NULL, *pos, *next_line; |
|
ssize_t ret; |
|
|
|
/* Only allow < page size writes at the beginning of the file */ |
|
if ((*ppos != 0) || (count >= PAGE_SIZE)) |
|
return -EINVAL; |
|
|
|
/* Slurp in the user data */ |
|
kbuf = memdup_user_nul(buf, count); |
|
if (IS_ERR(kbuf)) |
|
return PTR_ERR(kbuf); |
|
|
|
/* |
|
* The userns_state_mutex serializes all writes to any given map. |
|
* |
|
* Any map is only ever written once. |
|
* |
|
* An id map fits within 1 cache line on most architectures. |
|
* |
|
* On read nothing needs to be done unless you are on an |
|
* architecture with a crazy cache coherency model like alpha. |
|
* |
|
* There is a one time data dependency between reading the |
|
* count of the extents and the values of the extents. The |
|
* desired behavior is to see the values of the extents that |
|
* were written before the count of the extents. |
|
* |
|
* To achieve this smp_wmb() is used on guarantee the write |
|
* order and smp_rmb() is guaranteed that we don't have crazy |
|
* architectures returning stale data. |
|
*/ |
|
mutex_lock(&userns_state_mutex); |
|
|
|
memset(&new_map, 0, sizeof(struct uid_gid_map)); |
|
|
|
ret = -EPERM; |
|
/* Only allow one successful write to the map */ |
|
if (map->nr_extents != 0) |
|
goto out; |
|
|
|
/* |
|
* Adjusting namespace settings requires capabilities on the target. |
|
*/ |
|
if (cap_valid(cap_setid) && !file_ns_capable(file, map_ns, CAP_SYS_ADMIN)) |
|
goto out; |
|
|
|
/* Parse the user data */ |
|
ret = -EINVAL; |
|
pos = kbuf; |
|
for (; pos; pos = next_line) { |
|
|
|
/* Find the end of line and ensure I don't look past it */ |
|
next_line = strchr(pos, '\n'); |
|
if (next_line) { |
|
*next_line = '\0'; |
|
next_line++; |
|
if (*next_line == '\0') |
|
next_line = NULL; |
|
} |
|
|
|
pos = skip_spaces(pos); |
|
extent.first = simple_strtoul(pos, &pos, 10); |
|
if (!isspace(*pos)) |
|
goto out; |
|
|
|
pos = skip_spaces(pos); |
|
extent.lower_first = simple_strtoul(pos, &pos, 10); |
|
if (!isspace(*pos)) |
|
goto out; |
|
|
|
pos = skip_spaces(pos); |
|
extent.count = simple_strtoul(pos, &pos, 10); |
|
if (*pos && !isspace(*pos)) |
|
goto out; |
|
|
|
/* Verify there is not trailing junk on the line */ |
|
pos = skip_spaces(pos); |
|
if (*pos != '\0') |
|
goto out; |
|
|
|
/* Verify we have been given valid starting values */ |
|
if ((extent.first == (u32) -1) || |
|
(extent.lower_first == (u32) -1)) |
|
goto out; |
|
|
|
/* Verify count is not zero and does not cause the |
|
* extent to wrap |
|
*/ |
|
if ((extent.first + extent.count) <= extent.first) |
|
goto out; |
|
if ((extent.lower_first + extent.count) <= |
|
extent.lower_first) |
|
goto out; |
|
|
|
/* Do the ranges in extent overlap any previous extents? */ |
|
if (mappings_overlap(&new_map, &extent)) |
|
goto out; |
|
|
|
if ((new_map.nr_extents + 1) == UID_GID_MAP_MAX_EXTENTS && |
|
(next_line != NULL)) |
|
goto out; |
|
|
|
ret = insert_extent(&new_map, &extent); |
|
if (ret < 0) |
|
goto out; |
|
ret = -EINVAL; |
|
} |
|
/* Be very certain the new map actually exists */ |
|
if (new_map.nr_extents == 0) |
|
goto out; |
|
|
|
ret = -EPERM; |
|
/* Validate the user is allowed to use user id's mapped to. */ |
|
if (!new_idmap_permitted(file, map_ns, cap_setid, &new_map)) |
|
goto out; |
|
|
|
ret = -EPERM; |
|
/* Map the lower ids from the parent user namespace to the |
|
* kernel global id space. |
|
*/ |
|
for (idx = 0; idx < new_map.nr_extents; idx++) { |
|
struct uid_gid_extent *e; |
|
u32 lower_first; |
|
|
|
if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
|
e = &new_map.extent[idx]; |
|
else |
|
e = &new_map.forward[idx]; |
|
|
|
lower_first = map_id_range_down(parent_map, |
|
e->lower_first, |
|
e->count); |
|
|
|
/* Fail if we can not map the specified extent to |
|
* the kernel global id space. |
|
*/ |
|
if (lower_first == (u32) -1) |
|
goto out; |
|
|
|
e->lower_first = lower_first; |
|
} |
|
|
|
/* |
|
* If we want to use binary search for lookup, this clones the extent |
|
* array and sorts both copies. |
|
*/ |
|
ret = sort_idmaps(&new_map); |
|
if (ret < 0) |
|
goto out; |
|
|
|
/* Install the map */ |
|
if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) { |
|
memcpy(map->extent, new_map.extent, |
|
new_map.nr_extents * sizeof(new_map.extent[0])); |
|
} else { |
|
map->forward = new_map.forward; |
|
map->reverse = new_map.reverse; |
|
} |
|
smp_wmb(); |
|
map->nr_extents = new_map.nr_extents; |
|
|
|
*ppos = count; |
|
ret = count; |
|
out: |
|
if (ret < 0 && new_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
|
kfree(new_map.forward); |
|
kfree(new_map.reverse); |
|
map->forward = NULL; |
|
map->reverse = NULL; |
|
map->nr_extents = 0; |
|
} |
|
|
|
mutex_unlock(&userns_state_mutex); |
|
kfree(kbuf); |
|
return ret; |
|
} |
|
|
|
ssize_t proc_uid_map_write(struct file *file, const char __user *buf, |
|
size_t size, loff_t *ppos) |
|
{ |
|
struct seq_file *seq = file->private_data; |
|
struct user_namespace *ns = seq->private; |
|
struct user_namespace *seq_ns = seq_user_ns(seq); |
|
|
|
if (!ns->parent) |
|
return -EPERM; |
|
|
|
if ((seq_ns != ns) && (seq_ns != ns->parent)) |
|
return -EPERM; |
|
|
|
return map_write(file, buf, size, ppos, CAP_SETUID, |
|
&ns->uid_map, &ns->parent->uid_map); |
|
} |
|
|
|
ssize_t proc_gid_map_write(struct file *file, const char __user *buf, |
|
size_t size, loff_t *ppos) |
|
{ |
|
struct seq_file *seq = file->private_data; |
|
struct user_namespace *ns = seq->private; |
|
struct user_namespace *seq_ns = seq_user_ns(seq); |
|
|
|
if (!ns->parent) |
|
return -EPERM; |
|
|
|
if ((seq_ns != ns) && (seq_ns != ns->parent)) |
|
return -EPERM; |
|
|
|
return map_write(file, buf, size, ppos, CAP_SETGID, |
|
&ns->gid_map, &ns->parent->gid_map); |
|
} |
|
|
|
ssize_t proc_projid_map_write(struct file *file, const char __user *buf, |
|
size_t size, loff_t *ppos) |
|
{ |
|
struct seq_file *seq = file->private_data; |
|
struct user_namespace *ns = seq->private; |
|
struct user_namespace *seq_ns = seq_user_ns(seq); |
|
|
|
if (!ns->parent) |
|
return -EPERM; |
|
|
|
if ((seq_ns != ns) && (seq_ns != ns->parent)) |
|
return -EPERM; |
|
|
|
/* Anyone can set any valid project id no capability needed */ |
|
return map_write(file, buf, size, ppos, -1, |
|
&ns->projid_map, &ns->parent->projid_map); |
|
} |
|
|
|
static bool new_idmap_permitted(const struct file *file, |
|
struct user_namespace *ns, int cap_setid, |
|
struct uid_gid_map *new_map) |
|
{ |
|
const struct cred *cred = file->f_cred; |
|
|
|
if (cap_setid == CAP_SETUID && !verify_root_map(file, ns, new_map)) |
|
return false; |
|
|
|
/* Don't allow mappings that would allow anything that wouldn't |
|
* be allowed without the establishment of unprivileged mappings. |
|
*/ |
|
if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1) && |
|
uid_eq(ns->owner, cred->euid)) { |
|
u32 id = new_map->extent[0].lower_first; |
|
if (cap_setid == CAP_SETUID) { |
|
kuid_t uid = make_kuid(ns->parent, id); |
|
if (uid_eq(uid, cred->euid)) |
|
return true; |
|
} else if (cap_setid == CAP_SETGID) { |
|
kgid_t gid = make_kgid(ns->parent, id); |
|
if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) && |
|
gid_eq(gid, cred->egid)) |
|
return true; |
|
} |
|
} |
|
|
|
/* Allow anyone to set a mapping that doesn't require privilege */ |
|
if (!cap_valid(cap_setid)) |
|
return true; |
|
|
|
/* Allow the specified ids if we have the appropriate capability |
|
* (CAP_SETUID or CAP_SETGID) over the parent user namespace. |
|
* And the opener of the id file also has the appropriate capability. |
|
*/ |
|
if (ns_capable(ns->parent, cap_setid) && |
|
file_ns_capable(file, ns->parent, cap_setid)) |
|
return true; |
|
|
|
return false; |
|
} |
|
|
|
int proc_setgroups_show(struct seq_file *seq, void *v) |
|
{ |
|
struct user_namespace *ns = seq->private; |
|
unsigned long userns_flags = READ_ONCE(ns->flags); |
|
|
|
seq_printf(seq, "%s\n", |
|
(userns_flags & USERNS_SETGROUPS_ALLOWED) ? |
|
"allow" : "deny"); |
|
return 0; |
|
} |
|
|
|
ssize_t proc_setgroups_write(struct file *file, const char __user *buf, |
|
size_t count, loff_t *ppos) |
|
{ |
|
struct seq_file *seq = file->private_data; |
|
struct user_namespace *ns = seq->private; |
|
char kbuf[8], *pos; |
|
bool setgroups_allowed; |
|
ssize_t ret; |
|
|
|
/* Only allow a very narrow range of strings to be written */ |
|
ret = -EINVAL; |
|
if ((*ppos != 0) || (count >= sizeof(kbuf))) |
|
goto out; |
|
|
|
/* What was written? */ |
|
ret = -EFAULT; |
|
if (copy_from_user(kbuf, buf, count)) |
|
goto out; |
|
kbuf[count] = '\0'; |
|
pos = kbuf; |
|
|
|
/* What is being requested? */ |
|
ret = -EINVAL; |
|
if (strncmp(pos, "allow", 5) == 0) { |
|
pos += 5; |
|
setgroups_allowed = true; |
|
} |
|
else if (strncmp(pos, "deny", 4) == 0) { |
|
pos += 4; |
|
setgroups_allowed = false; |
|
} |
|
else |
|
goto out; |
|
|
|
/* Verify there is not trailing junk on the line */ |
|
pos = skip_spaces(pos); |
|
if (*pos != '\0') |
|
goto out; |
|
|
|
ret = -EPERM; |
|
mutex_lock(&userns_state_mutex); |
|
if (setgroups_allowed) { |
|
/* Enabling setgroups after setgroups has been disabled |
|
* is not allowed. |
|
*/ |
|
if (!(ns->flags & USERNS_SETGROUPS_ALLOWED)) |
|
goto out_unlock; |
|
} else { |
|
/* Permanently disabling setgroups after setgroups has |
|
* been enabled by writing the gid_map is not allowed. |
|
*/ |
|
if (ns->gid_map.nr_extents != 0) |
|
goto out_unlock; |
|
ns->flags &= ~USERNS_SETGROUPS_ALLOWED; |
|
} |
|
mutex_unlock(&userns_state_mutex); |
|
|
|
/* Report a successful write */ |
|
*ppos = count; |
|
ret = count; |
|
out: |
|
return ret; |
|
out_unlock: |
|
mutex_unlock(&userns_state_mutex); |
|
goto out; |
|
} |
|
|
|
bool userns_may_setgroups(const struct user_namespace *ns) |
|
{ |
|
bool allowed; |
|
|
|
mutex_lock(&userns_state_mutex); |
|
/* It is not safe to use setgroups until a gid mapping in |
|
* the user namespace has been established. |
|
*/ |
|
allowed = ns->gid_map.nr_extents != 0; |
|
/* Is setgroups allowed? */ |
|
allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED); |
|
mutex_unlock(&userns_state_mutex); |
|
|
|
return allowed; |
|
} |
|
|
|
/* |
|
* Returns true if @child is the same namespace or a descendant of |
|
* @ancestor. |
|
*/ |
|
bool in_userns(const struct user_namespace *ancestor, |
|
const struct user_namespace *child) |
|
{ |
|
const struct user_namespace *ns; |
|
for (ns = child; ns->level > ancestor->level; ns = ns->parent) |
|
; |
|
return (ns == ancestor); |
|
} |
|
|
|
bool current_in_userns(const struct user_namespace *target_ns) |
|
{ |
|
return in_userns(target_ns, current_user_ns()); |
|
} |
|
EXPORT_SYMBOL(current_in_userns); |
|
|
|
static inline struct user_namespace *to_user_ns(struct ns_common *ns) |
|
{ |
|
return container_of(ns, struct user_namespace, ns); |
|
} |
|
|
|
static struct ns_common *userns_get(struct task_struct *task) |
|
{ |
|
struct user_namespace *user_ns; |
|
|
|
rcu_read_lock(); |
|
user_ns = get_user_ns(__task_cred(task)->user_ns); |
|
rcu_read_unlock(); |
|
|
|
return user_ns ? &user_ns->ns : NULL; |
|
} |
|
|
|
static void userns_put(struct ns_common *ns) |
|
{ |
|
put_user_ns(to_user_ns(ns)); |
|
} |
|
|
|
static int userns_install(struct nsset *nsset, struct ns_common *ns) |
|
{ |
|
struct user_namespace *user_ns = to_user_ns(ns); |
|
struct cred *cred; |
|
|
|
/* Don't allow gaining capabilities by reentering |
|
* the same user namespace. |
|
*/ |
|
if (user_ns == current_user_ns()) |
|
return -EINVAL; |
|
|
|
/* Tasks that share a thread group must share a user namespace */ |
|
if (!thread_group_empty(current)) |
|
return -EINVAL; |
|
|
|
if (current->fs->users != 1) |
|
return -EINVAL; |
|
|
|
if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
|
return -EPERM; |
|
|
|
cred = nsset_cred(nsset); |
|
if (!cred) |
|
return -EINVAL; |
|
|
|
put_user_ns(cred->user_ns); |
|
set_cred_user_ns(cred, get_user_ns(user_ns)); |
|
|
|
if (set_cred_ucounts(cred) < 0) |
|
return -EINVAL; |
|
|
|
return 0; |
|
} |
|
|
|
struct ns_common *ns_get_owner(struct ns_common *ns) |
|
{ |
|
struct user_namespace *my_user_ns = current_user_ns(); |
|
struct user_namespace *owner, *p; |
|
|
|
/* See if the owner is in the current user namespace */ |
|
owner = p = ns->ops->owner(ns); |
|
for (;;) { |
|
if (!p) |
|
return ERR_PTR(-EPERM); |
|
if (p == my_user_ns) |
|
break; |
|
p = p->parent; |
|
} |
|
|
|
return &get_user_ns(owner)->ns; |
|
} |
|
|
|
static struct user_namespace *userns_owner(struct ns_common *ns) |
|
{ |
|
return to_user_ns(ns)->parent; |
|
} |
|
|
|
const struct proc_ns_operations userns_operations = { |
|
.name = "user", |
|
.type = CLONE_NEWUSER, |
|
.get = userns_get, |
|
.put = userns_put, |
|
.install = userns_install, |
|
.owner = userns_owner, |
|
.get_parent = ns_get_owner, |
|
}; |
|
|
|
static __init int user_namespaces_init(void) |
|
{ |
|
user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC | SLAB_ACCOUNT); |
|
return 0; |
|
} |
|
subsys_initcall(user_namespaces_init);
|
|
|