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kernel/user_namespace.c
33.2 KB
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// 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> #include <linux/key-type.h> #include <keys/user-type.h> #include <linux/seq_file.h> #include <linux/fs.h> #include <linux/uaccess.h> #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> #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, 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) { return inc_ucount(ns, uid, UCOUNT_USER_NAMESPACES); } static void dec_user_namespaces(struct ucounts *ucounts) { return dec_ucount(ucounts, UCOUNT_USER_NAMESPACES); } |
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static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns) { /* Start with the same capabilities as init but useless for doing * anything as the capabilities are bound to the new user namespace. */ cred->securebits = SECUREBITS_DEFAULT; cred->cap_inheritable = CAP_EMPTY_SET; cred->cap_permitted = CAP_FULL_SET; 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; #ifdef CONFIG_KEYS key_put(cred->request_key_auth); cred->request_key_auth = NULL; #endif /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */ cred->user_ns = user_ns; } |
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/* |
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* Create a new user namespace, deriving the creator from the user in the * passed credentials, and replacing that user with the new root user for the * new namespace. * * This is called by copy_creds(), which will finish setting the target task's * 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; 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); if (!ucounts) |
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goto fail; |
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/* * Verify that we can not violate the policy of which files * may be accessed that is specified by the root directory, * by verifing that the root directory is at the root of the * mount namespace which allows all files to be accessed. */ |
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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 * or else we won't be able to reasonably tell userspace who * created a user_namespace. */ |
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ret = -EPERM; |
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if (!kuid_has_mapping(parent_ns, owner) || !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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ret = ns_alloc_inum(&ns->ns); |
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if (ret) goto fail_free; |
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ns->ns.ops = &userns_operations; |
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atomic_set(&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; ns->group = group; |
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INIT_WORK(&ns->work, free_user_ns); |
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for (i = 0; i < UCOUNT_COUNTS; i++) { ns->ucount_max[i] = INT_MAX; } |
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ns->ucounts = ucounts; |
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/* Inherit USERNS_SETGROUPS_ALLOWED from our parent */ mutex_lock(&userns_state_mutex); ns->flags = parent_ns->flags; mutex_unlock(&userns_state_mutex); |
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#ifdef CONFIG_KEYS 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; if (!setup_userns_sysctls(ns)) goto fail_keyring; set_cred_user_ns(new, ns); |
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return 0; |
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fail_keyring: #ifdef CONFIG_PERSISTENT_KEYRINGS key_put(ns->persistent_keyring_register); #endif 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) { struct cred *cred; |
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int err = -ENOMEM; |
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if (!(unshare_flags & CLONE_NEWUSER)) return 0; cred = prepare_creds(); |
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if (cred) { err = create_user_ns(cred); if (err) put_cred(cred); else *new_cred = cred; } |
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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 = 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) { kfree(ns->gid_map.forward); kfree(ns->gid_map.reverse); } if (ns->uid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { kfree(ns->uid_map.forward); kfree(ns->uid_map.reverse); } if (ns->projid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { kfree(ns->projid_map.forward); kfree(ns->projid_map.reverse); } |
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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; } while (atomic_dec_and_test(&parent->count)); |
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} |
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void __put_user_ns(struct user_namespace *ns) { schedule_work(&ns->work); } EXPORT_SYMBOL(__put_user_ns); |
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/** * idmap_key struct holds the information necessary to find an idmapping in a * sorted idmap array. It is passed to cmp_map_id() as first argument. */ struct idmap_key { bool map_up; /* true -> id from kid; false -> kid from id */ u32 id; /* id to find */ u32 count; /* == 0 unless used with map_id_range_down() */ }; /** * cmp_map_id - Function to be passed to bsearch() to find the requested * idmapping. Expects struct idmap_key to be passed via @k. */ static int cmp_map_id(const void *k, const void *e) { u32 first, last, id2; const struct idmap_key *key = k; 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}() */ if (key->map_up) first = el->lower_first; else first = el->first; last = first + el->count - 1; if (key->id >= first && key->id <= last && (id2 >= first && id2 <= last)) return 0; if (key->id < first || id2 < first) return -1; return 1; } /** * map_id_range_down_max - Find idmap via binary search in ordered idmap array. * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. */ |
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static struct uid_gid_extent * 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; key.map_up = false; key.count = count; key.id = id; |
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return bsearch(&key, map->forward, extents, sizeof(struct uid_gid_extent), cmp_map_id); |
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} /** * map_id_range_down_base - Find idmap via binary search in static extent array. * Can only be called if number of mappings is equal or less than * UID_GID_MAP_MAX_BASE_EXTENTS. */ |
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static struct uid_gid_extent * 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++) { first = map->extent[idx].first; last = first + map->extent[idx].count - 1; if (id >= first && id <= last && (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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struct uid_gid_extent *extent; unsigned extents = map->nr_extents; |
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smp_rmb(); if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
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extent = map_id_range_down_base(extents, map, id, count); else 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) id = (id - extent->first) + extent->lower_first; |
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else id = (u32) -1; return id; } static u32 map_id_down(struct uid_gid_map *map, u32 id) { |
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return map_id_range_down(map, id, 1); |
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} /** * map_id_up_base - Find idmap via binary search in static extent array. * Can only be called if number of mappings is equal or less than * UID_GID_MAP_MAX_BASE_EXTENTS. */ |
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static struct uid_gid_extent * 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; /* 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; 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. * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. */ |
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static struct uid_gid_extent * 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; 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, sizeof(struct uid_gid_extent), cmp_map_id); |
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} static u32 map_id_up(struct uid_gid_map *map, u32 id) { |
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struct uid_gid_extent *extent; unsigned extents = map->nr_extents; |
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smp_rmb(); |
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if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) extent = map_id_up_base(extents, map, id); else extent = map_id_up_max(extents, map, id); |
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/* Map the id or note failure */ |
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if (extent) id = (id - extent->lower_first) + extent->first; |
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else id = (u32) -1; return id; } /** * make_kuid - Map a user-namespace uid pair into a kuid. * @ns: User namespace that the uid is in * @uid: User identifier * * Maps a user-namespace uid pair into a kernel internal kuid, * and returns that kuid. * * When there is no mapping defined for the user-namespace uid * 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(). */ kuid_t make_kuid(struct user_namespace *ns, uid_t uid) { /* Map the uid to a global kernel uid */ return KUIDT_INIT(map_id_down(&ns->uid_map, uid)); } EXPORT_SYMBOL(make_kuid); /** * from_kuid - Create a uid from a kuid user-namespace pair. * @targ: The user namespace we want a uid in. * @kuid: The kernel internal uid to start with. * * Map @kuid into the user-namespace specified by @targ and * return the resulting uid. * * There is always a mapping into the initial user_namespace. * * If @kuid has no mapping in @targ (uid_t)-1 is returned. */ uid_t from_kuid(struct user_namespace *targ, kuid_t kuid) { /* Map the uid from a global kernel uid */ return map_id_up(&targ->uid_map, __kuid_val(kuid)); } EXPORT_SYMBOL(from_kuid); /** * from_kuid_munged - Create a uid from a kuid user-namespace pair. * @targ: The user namespace we want a uid in. * @kuid: The kernel internal uid to start with. * * Map @kuid into the user-namespace specified by @targ and * return the resulting uid. * * There is always a mapping into the initial user_namespace. * * Unlike from_kuid from_kuid_munged never fails and always * returns a valid uid. This makes from_kuid_munged appropriate * for use in syscalls like stat and getuid where failing the * system call and failing to provide a valid uid are not an * options. * * If @kuid has no mapping in @targ overflowuid is returned. */ uid_t from_kuid_munged(struct user_namespace *targ, kuid_t kuid) { uid_t uid; uid = from_kuid(targ, kuid); if (uid == (uid_t) -1) uid = overflowuid; return uid; } EXPORT_SYMBOL(from_kuid_munged); /** * make_kgid - Map a user-namespace gid pair into a kgid. * @ns: User namespace that the gid is in |
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* @gid: group identifier |
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* * Maps a user-namespace gid pair into a kernel internal kgid, * and returns that kgid. * * When there is no mapping defined for the user-namespace gid * pair INVALID_GID is returned. Callers are expected to test * for and handle INVALID_GID being returned. INVALID_GID may be * tested for using gid_valid(). */ kgid_t make_kgid(struct user_namespace *ns, gid_t gid) { /* Map the gid to a global kernel gid */ return KGIDT_INIT(map_id_down(&ns->gid_map, gid)); } EXPORT_SYMBOL(make_kgid); /** * from_kgid - Create a gid from a kgid user-namespace pair. * @targ: The user namespace we want a gid in. * @kgid: The kernel internal gid to start with. * * Map @kgid into the user-namespace specified by @targ and * return the resulting gid. * * There is always a mapping into the initial user_namespace. * * If @kgid has no mapping in @targ (gid_t)-1 is returned. */ gid_t from_kgid(struct user_namespace *targ, kgid_t kgid) { /* Map the gid from a global kernel gid */ return map_id_up(&targ->gid_map, __kgid_val(kgid)); } EXPORT_SYMBOL(from_kgid); /** * from_kgid_munged - Create a gid from a kgid user-namespace pair. * @targ: The user namespace we want a gid in. * @kgid: The kernel internal gid to start with. * * Map @kgid into the user-namespace specified by @targ and * return the resulting gid. * * There is always a mapping into the initial user_namespace. * * Unlike from_kgid from_kgid_munged never fails and always * returns a valid gid. This makes from_kgid_munged appropriate * for use in syscalls like stat and getgid where failing the * system call and failing to provide a valid gid are not options. * * If @kgid has no mapping in @targ overflowgid is returned. */ gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid) { gid_t gid; gid = from_kgid(targ, kgid); if (gid == (gid_t) -1) gid = overflowgid; return gid; } EXPORT_SYMBOL(from_kgid_munged); |
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/** * make_kprojid - Map a user-namespace projid pair into a kprojid. * @ns: User namespace that the projid is in * @projid: Project identifier * * Maps a user-namespace uid pair into a kernel internal kuid, * and returns that kuid. * * When there is no mapping defined for the user-namespace projid * pair INVALID_PROJID is returned. Callers are expected to test * for and handle handle INVALID_PROJID being returned. INVALID_PROJID * may be tested for using projid_valid(). */ kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid) { /* Map the uid to a global kernel uid */ return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid)); } EXPORT_SYMBOL(make_kprojid); /** * from_kprojid - Create a projid from a kprojid user-namespace pair. * @targ: The user namespace we want a projid in. * @kprojid: The kernel internal project identifier 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. * * If @kprojid has no mapping in @targ (projid_t)-1 is returned. */ projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid) { /* Map the uid from a global kernel uid */ return map_id_up(&targ->projid_map, __kprojid_val(kprojid)); } 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); |
22d917d80
|
562 563 564 565 566 567 |
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; |
5c1469de7
|
568 |
|
c450f371d
|
569 |
lower_ns = seq_user_ns(seq); |
22d917d80
|
570 571 572 573 574 575 576 577 578 579 580 581 |
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 ", extent->first, lower, extent->count); return 0; |
5c1469de7
|
582 |
} |
22d917d80
|
583 |
static int gid_m_show(struct seq_file *seq, void *v) |
5c1469de7
|
584 |
{ |
22d917d80
|
585 586 587 588 |
struct user_namespace *ns = seq->private; struct uid_gid_extent *extent = v; struct user_namespace *lower_ns; gid_t lower; |
5c1469de7
|
589 |
|
c450f371d
|
590 |
lower_ns = seq_user_ns(seq); |
22d917d80
|
591 592 |
if ((lower_ns == ns) && lower_ns->parent) lower_ns = lower_ns->parent; |
5c1469de7
|
593 |
|
22d917d80
|
594 595 596 597 598 599 600 601 602 603 |
lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first)); seq_printf(seq, "%10u %10u %10u ", extent->first, lower, extent->count); return 0; } |
f76d207a6
|
604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 |
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 ", extent->first, lower, extent->count); return 0; } |
68a9a435e
|
625 626 |
static void *m_start(struct seq_file *seq, loff_t *ppos, struct uid_gid_map *map) |
22d917d80
|
627 |
{ |
22d917d80
|
628 |
loff_t pos = *ppos; |
d5e7b3c5f
|
629 630 |
unsigned extents = map->nr_extents; smp_rmb(); |
22d917d80
|
631 |
|
d5e7b3c5f
|
632 |
if (pos >= extents) |
6397fac49
|
633 |
return NULL; |
22d917d80
|
634 |
|
d5e7b3c5f
|
635 |
if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
6397fac49
|
636 |
return &map->extent[pos]; |
22d917d80
|
637 |
|
6397fac49
|
638 |
return &map->forward[pos]; |
22d917d80
|
639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 |
} 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); } |
f76d207a6
|
654 655 656 657 658 659 |
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); } |
22d917d80
|
660 661 662 663 664 665 666 667 668 669 |
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; } |
ccf94f1b4
|
670 |
const struct seq_operations proc_uid_seq_operations = { |
22d917d80
|
671 672 673 674 675 |
.start = uid_m_start, .stop = m_stop, .next = m_next, .show = uid_m_show, }; |
ccf94f1b4
|
676 |
const struct seq_operations proc_gid_seq_operations = { |
22d917d80
|
677 678 679 680 681 |
.start = gid_m_start, .stop = m_stop, .next = m_next, .show = gid_m_show, }; |
ccf94f1b4
|
682 |
const struct seq_operations proc_projid_seq_operations = { |
f76d207a6
|
683 684 685 686 687 |
.start = projid_m_start, .stop = m_stop, .next = m_next, .show = projid_m_show, }; |
68a9a435e
|
688 689 |
static bool mappings_overlap(struct uid_gid_map *new_map, struct uid_gid_extent *extent) |
0bd14b4fd
|
690 691 692 693 694 695 696 697 698 699 700 701 702 |
{ 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; |
6397fac49
|
703 704 705 706 |
if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) prev = &new_map->extent[idx]; else prev = &new_map->forward[idx]; |
0bd14b4fd
|
707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 |
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; } |
6397fac49
|
725 726 727 728 729 730 731 |
/** * 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) { |
3fda0e737
|
732 |
struct uid_gid_extent *dest; |
6397fac49
|
733 734 735 736 737 |
if (map->nr_extents == UID_GID_MAP_MAX_BASE_EXTENTS) { struct uid_gid_extent *forward; /* Allocate memory for 340 mappings. */ |
6da2ec560
|
738 739 740 |
forward = kmalloc_array(UID_GID_MAP_MAX_EXTENTS, sizeof(struct uid_gid_extent), GFP_KERNEL); |
6397fac49
|
741 742 743 744 745 746 747 748 749 750 751 752 |
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; } |
3fda0e737
|
753 754 755 756 757 758 759 |
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++; |
6397fac49
|
760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 |
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; } |
22d917d80
|
819 820 821 822 823 824 825 826 827 828 |
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 *ns = seq->private; struct uid_gid_map new_map; unsigned idx; |
6397fac49
|
829 |
struct uid_gid_extent extent; |
70f6cbb6f
|
830 |
char *kbuf = NULL, *pos, *next_line; |
5820f140e
|
831 832 833 834 835 836 837 838 839 840 |
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); |
22d917d80
|
841 842 |
/* |
f0d62aec9
|
843 |
* The userns_state_mutex serializes all writes to any given map. |
22d917d80
|
844 845 846 847 848 849 850 851 852 853 854 855 856 857 |
* * 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 |
e79323bd8
|
858 859 |
* order and smp_rmb() is guaranteed that we don't have crazy * architectures returning stale data. |
22d917d80
|
860 |
*/ |
f0d62aec9
|
861 |
mutex_lock(&userns_state_mutex); |
22d917d80
|
862 |
|
6397fac49
|
863 |
memset(&new_map, 0, sizeof(struct uid_gid_map)); |
22d917d80
|
864 865 866 867 |
ret = -EPERM; /* Only allow one successful write to the map */ if (map->nr_extents != 0) goto out; |
41c21e351
|
868 869 |
/* * Adjusting namespace settings requires capabilities on the target. |
5c1469de7
|
870 |
*/ |
41c21e351
|
871 |
if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN)) |
22d917d80
|
872 |
goto out; |
22d917d80
|
873 874 875 |
/* Parse the user data */ ret = -EINVAL; pos = kbuf; |
68a9a435e
|
876 |
for (; pos; pos = next_line) { |
22d917d80
|
877 878 879 880 881 882 883 884 885 |
/* Find the end of line and ensure I don't look past it */ next_line = strchr(pos, ' '); if (next_line) { *next_line = '\0'; next_line++; if (*next_line == '\0') next_line = NULL; |
5c1469de7
|
886 |
} |
22d917d80
|
887 888 |
pos = skip_spaces(pos); |
6397fac49
|
889 |
extent.first = simple_strtoul(pos, &pos, 10); |
22d917d80
|
890 891 892 893 |
if (!isspace(*pos)) goto out; pos = skip_spaces(pos); |
6397fac49
|
894 |
extent.lower_first = simple_strtoul(pos, &pos, 10); |
22d917d80
|
895 896 897 898 |
if (!isspace(*pos)) goto out; pos = skip_spaces(pos); |
6397fac49
|
899 |
extent.count = simple_strtoul(pos, &pos, 10); |
22d917d80
|
900 901 902 903 904 905 906 907 908 |
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 */ |
6397fac49
|
909 910 |
if ((extent.first == (u32) -1) || (extent.lower_first == (u32) -1)) |
22d917d80
|
911 |
goto out; |
68a9a435e
|
912 913 914 |
/* Verify count is not zero and does not cause the * extent to wrap */ |
6397fac49
|
915 |
if ((extent.first + extent.count) <= extent.first) |
22d917d80
|
916 |
goto out; |
6397fac49
|
917 918 |
if ((extent.lower_first + extent.count) <= extent.lower_first) |
22d917d80
|
919 |
goto out; |
0bd14b4fd
|
920 |
/* Do the ranges in extent overlap any previous extents? */ |
6397fac49
|
921 |
if (mappings_overlap(&new_map, &extent)) |
22d917d80
|
922 |
goto out; |
6397fac49
|
923 |
if ((new_map.nr_extents + 1) == UID_GID_MAP_MAX_EXTENTS && |
22d917d80
|
924 925 |
(next_line != NULL)) goto out; |
6397fac49
|
926 927 928 929 930 |
ret = insert_extent(&new_map, &extent); if (ret < 0) goto out; ret = -EINVAL; |
5c1469de7
|
931 |
} |
22d917d80
|
932 933 934 935 936 937 |
/* Be very certaint 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. */ |
6708075f1
|
938 |
if (!new_idmap_permitted(file, ns, cap_setid, &new_map)) |
22d917d80
|
939 |
goto out; |
6397fac49
|
940 |
ret = -EPERM; |
22d917d80
|
941 942 943 944 |
/* Map the lower ids from the parent user namespace to the * kernel global id space. */ for (idx = 0; idx < new_map.nr_extents; idx++) { |
6397fac49
|
945 |
struct uid_gid_extent *e; |
22d917d80
|
946 |
u32 lower_first; |
6397fac49
|
947 948 949 950 951 |
if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) e = &new_map.extent[idx]; else e = &new_map.forward[idx]; |
22d917d80
|
952 953 |
lower_first = map_id_range_down(parent_map, |
6397fac49
|
954 955 |
e->lower_first, e->count); |
22d917d80
|
956 957 958 959 960 961 |
/* Fail if we can not map the specified extent to * the kernel global id space. */ if (lower_first == (u32) -1) goto out; |
6397fac49
|
962 |
e->lower_first = lower_first; |
22d917d80
|
963 |
} |
d2f007dbe
|
964 965 966 967 968 969 970 |
/* * 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; |
22d917d80
|
971 |
/* Install the map */ |
6397fac49
|
972 973 974 975 976 977 978 |
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; } |
22d917d80
|
979 980 981 982 983 984 |
smp_wmb(); map->nr_extents = new_map.nr_extents; *ppos = count; ret = count; out: |
6397fac49
|
985 986 987 988 989 990 991 |
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; } |
f0d62aec9
|
992 |
mutex_unlock(&userns_state_mutex); |
70f6cbb6f
|
993 |
kfree(kbuf); |
22d917d80
|
994 995 |
return ret; } |
68a9a435e
|
996 997 |
ssize_t proc_uid_map_write(struct file *file, const char __user *buf, size_t size, loff_t *ppos) |
22d917d80
|
998 999 1000 |
{ struct seq_file *seq = file->private_data; struct user_namespace *ns = seq->private; |
c450f371d
|
1001 |
struct user_namespace *seq_ns = seq_user_ns(seq); |
22d917d80
|
1002 1003 1004 |
if (!ns->parent) return -EPERM; |
c450f371d
|
1005 1006 |
if ((seq_ns != ns) && (seq_ns != ns->parent)) return -EPERM; |
22d917d80
|
1007 1008 1009 |
return map_write(file, buf, size, ppos, CAP_SETUID, &ns->uid_map, &ns->parent->uid_map); } |
68a9a435e
|
1010 1011 |
ssize_t proc_gid_map_write(struct file *file, const char __user *buf, size_t size, loff_t *ppos) |
22d917d80
|
1012 1013 1014 |
{ struct seq_file *seq = file->private_data; struct user_namespace *ns = seq->private; |
c450f371d
|
1015 |
struct user_namespace *seq_ns = seq_user_ns(seq); |
22d917d80
|
1016 1017 1018 |
if (!ns->parent) return -EPERM; |
c450f371d
|
1019 1020 |
if ((seq_ns != ns) && (seq_ns != ns->parent)) return -EPERM; |
22d917d80
|
1021 1022 1023 |
return map_write(file, buf, size, ppos, CAP_SETGID, &ns->gid_map, &ns->parent->gid_map); } |
68a9a435e
|
1024 1025 |
ssize_t proc_projid_map_write(struct file *file, const char __user *buf, size_t size, loff_t *ppos) |
f76d207a6
|
1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 |
{ 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); } |
68a9a435e
|
1041 |
static bool new_idmap_permitted(const struct file *file, |
6708075f1
|
1042 |
struct user_namespace *ns, int cap_setid, |
22d917d80
|
1043 1044 |
struct uid_gid_map *new_map) { |
f95d7918b
|
1045 |
const struct cred *cred = file->f_cred; |
0542f17bf
|
1046 1047 1048 |
/* Don't allow mappings that would allow anything that wouldn't * be allowed without the establishment of unprivileged mappings. */ |
f95d7918b
|
1049 1050 |
if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1) && uid_eq(ns->owner, cred->euid)) { |
37657da3c
|
1051 1052 1053 |
u32 id = new_map->extent[0].lower_first; if (cap_setid == CAP_SETUID) { kuid_t uid = make_kuid(ns->parent, id); |
f95d7918b
|
1054 |
if (uid_eq(uid, cred->euid)) |
37657da3c
|
1055 |
return true; |
68a9a435e
|
1056 |
} else if (cap_setid == CAP_SETGID) { |
37657da3c
|
1057 |
kgid_t gid = make_kgid(ns->parent, id); |
66d2f338e
|
1058 1059 |
if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) && gid_eq(gid, cred->egid)) |
37657da3c
|
1060 1061 1062 |
return true; } } |
f76d207a6
|
1063 1064 1065 |
/* Allow anyone to set a mapping that doesn't require privilege */ if (!cap_valid(cap_setid)) return true; |
22d917d80
|
1066 1067 |
/* Allow the specified ids if we have the appropriate capability * (CAP_SETUID or CAP_SETGID) over the parent user namespace. |
6708075f1
|
1068 |
* And the opener of the id file also had the approprpiate capability. |
22d917d80
|
1069 |
*/ |
6708075f1
|
1070 1071 |
if (ns_capable(ns->parent, cap_setid) && file_ns_capable(file, ns->parent, cap_setid)) |
22d917d80
|
1072 |
return true; |
5c1469de7
|
1073 |
|
22d917d80
|
1074 |
return false; |
5c1469de7
|
1075 |
} |
6164281ab
|
1076 |
|
9cc46516d
|
1077 1078 1079 |
int proc_setgroups_show(struct seq_file *seq, void *v) { struct user_namespace *ns = seq->private; |
6aa7de059
|
1080 |
unsigned long userns_flags = READ_ONCE(ns->flags); |
9cc46516d
|
1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 |
seq_printf(seq, "%s ", (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; } |
273d2c67c
|
1155 1156 1157 |
bool userns_may_setgroups(const struct user_namespace *ns) { bool allowed; |
f0d62aec9
|
1158 |
mutex_lock(&userns_state_mutex); |
273d2c67c
|
1159 1160 1161 1162 |
/* 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; |
9cc46516d
|
1163 1164 |
/* Is setgroups allowed? */ allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED); |
f0d62aec9
|
1165 |
mutex_unlock(&userns_state_mutex); |
273d2c67c
|
1166 1167 1168 |
return allowed; } |
d07b846f6
|
1169 |
/* |
a2b426267
|
1170 1171 |
* Returns true if @child is the same namespace or a descendant of * @ancestor. |
d07b846f6
|
1172 |
*/ |
a2b426267
|
1173 1174 1175 1176 1177 1178 1179 1180 |
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); } |
d07b846f6
|
1181 1182 |
bool current_in_userns(const struct user_namespace *target_ns) { |
a2b426267
|
1183 |
return in_userns(target_ns, current_user_ns()); |
d07b846f6
|
1184 |
} |
73f03c2b4
|
1185 |
EXPORT_SYMBOL(current_in_userns); |
d07b846f6
|
1186 |
|
3c0411846
|
1187 1188 1189 1190 |
static inline struct user_namespace *to_user_ns(struct ns_common *ns) { return container_of(ns, struct user_namespace, ns); } |
64964528b
|
1191 |
static struct ns_common *userns_get(struct task_struct *task) |
cde1975bc
|
1192 1193 1194 1195 1196 1197 |
{ struct user_namespace *user_ns; rcu_read_lock(); user_ns = get_user_ns(__task_cred(task)->user_ns); rcu_read_unlock(); |
3c0411846
|
1198 |
return user_ns ? &user_ns->ns : NULL; |
cde1975bc
|
1199 |
} |
64964528b
|
1200 |
static void userns_put(struct ns_common *ns) |
cde1975bc
|
1201 |
{ |
3c0411846
|
1202 |
put_user_ns(to_user_ns(ns)); |
cde1975bc
|
1203 |
} |
64964528b
|
1204 |
static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns) |
cde1975bc
|
1205 |
{ |
3c0411846
|
1206 |
struct user_namespace *user_ns = to_user_ns(ns); |
cde1975bc
|
1207 1208 1209 1210 1211 1212 1213 |
struct cred *cred; /* Don't allow gaining capabilities by reentering * the same user namespace. */ if (user_ns == current_user_ns()) return -EINVAL; |
faf00da54
|
1214 1215 |
/* Tasks that share a thread group must share a user namespace */ if (!thread_group_empty(current)) |
cde1975bc
|
1216 |
return -EINVAL; |
e66eded83
|
1217 1218 |
if (current->fs->users != 1) return -EINVAL; |
cde1975bc
|
1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 |
if (!ns_capable(user_ns, CAP_SYS_ADMIN)) return -EPERM; cred = prepare_creds(); if (!cred) return -ENOMEM; put_user_ns(cred->user_ns); set_cred_user_ns(cred, get_user_ns(user_ns)); return commit_creds(cred); } |
bcac25a58
|
1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 |
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; } |
cde1975bc
|
1253 1254 1255 1256 1257 1258 |
const struct proc_ns_operations userns_operations = { .name = "user", .type = CLONE_NEWUSER, .get = userns_get, .put = userns_put, .install = userns_install, |
bcac25a58
|
1259 |
.owner = userns_owner, |
a7306ed8d
|
1260 |
.get_parent = ns_get_owner, |
cde1975bc
|
1261 |
}; |
6164281ab
|
1262 1263 1264 1265 1266 |
static __init int user_namespaces_init(void) { user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC); return 0; } |
c96d6660d
|
1267 |
subsys_initcall(user_namespaces_init); |