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- // SPDX-License-Identifier: GPL-2.0-only
- #include <linux/export.h>
- #include <linux/nsproxy.h>
- #include <linux/slab.h>
- #include <linux/sched/signal.h>
- #include <linux/user_namespace.h>
- #include <linux/proc_ns.h>
- #include <linux/highuid.h>
- #include <linux/cred.h>
- #include <linux/securebits.h>
- #include <linux/security.h>
- #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>
- #include <linux/projid.h>
- #include <linux/fs_struct.h>
- #include <linux/bsearch.h>
- #include <linux/sort.h>
- static struct kmem_cache *user_ns_cachep __read_mostly;
- static DEFINE_MUTEX(userns_state_mutex);
- static bool new_idmap_permitted(const struct file *file,
- struct user_namespace *ns, int cap_setid,
- struct uid_gid_map *map);
- static void free_user_ns(struct work_struct *work);
- 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);
- }
- 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;
- cred->cap_ambient = CAP_EMPTY_SET;
- 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;
- }
- static unsigned long enforced_nproc_rlimit(void)
- {
- unsigned long limit = RLIM_INFINITY;
- /* Is RLIMIT_NPROC currently enforced? */
- if (!uid_eq(current_uid(), GLOBAL_ROOT_UID) ||
- (current_user_ns() != &init_user_ns))
- limit = rlimit(RLIMIT_NPROC);
- return limit;
- }
- /*
- * 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.
- */
- int create_user_ns(struct cred *new)
- {
- struct user_namespace *ns, *parent_ns = new->user_ns;
- kuid_t owner = new->euid;
- kgid_t group = new->egid;
- struct ucounts *ucounts;
- int ret, i;
- ret = -ENOSPC;
- if (parent_ns->level > 32)
- goto fail;
- ucounts = inc_user_namespaces(parent_ns, owner);
- if (!ucounts)
- goto fail;
- /*
- * Verify that we can not violate the policy of which files
- * may be accessed that is specified by the root directory,
- * by verifying that the root directory is at the root of the
- * mount namespace which allows all files to be accessed.
- */
- ret = -EPERM;
- if (current_chrooted())
- goto fail_dec;
- /* 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.
- */
- ret = -EPERM;
- if (!kuid_has_mapping(parent_ns, owner) ||
- !kgid_has_mapping(parent_ns, group))
- goto fail_dec;
- ret = security_create_user_ns(new);
- if (ret < 0)
- goto fail_dec;
- ret = -ENOMEM;
- ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL);
- if (!ns)
- goto fail_dec;
- ns->parent_could_setfcap = cap_raised(new->cap_effective, CAP_SETFCAP);
- ret = ns_alloc_inum(&ns->ns);
- if (ret)
- goto fail_free;
- ns->ns.ops = &userns_operations;
- refcount_set(&ns->ns.count, 1);
- /* Leave the new->user_ns reference with the new user namespace. */
- ns->parent = parent_ns;
- ns->level = parent_ns->level + 1;
- ns->owner = owner;
- ns->group = group;
- INIT_WORK(&ns->work, free_user_ns);
- for (i = 0; i < UCOUNT_COUNTS; i++) {
- ns->ucount_max[i] = INT_MAX;
- }
- set_userns_rlimit_max(ns, UCOUNT_RLIMIT_NPROC, enforced_nproc_rlimit());
- set_userns_rlimit_max(ns, UCOUNT_RLIMIT_MSGQUEUE, rlimit(RLIMIT_MSGQUEUE));
- set_userns_rlimit_max(ns, UCOUNT_RLIMIT_SIGPENDING, rlimit(RLIMIT_SIGPENDING));
- set_userns_rlimit_max(ns, UCOUNT_RLIMIT_MEMLOCK, rlimit(RLIMIT_MEMLOCK));
- ns->ucounts = ucounts;
- /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
- mutex_lock(&userns_state_mutex);
- ns->flags = parent_ns->flags;
- mutex_unlock(&userns_state_mutex);
- #ifdef CONFIG_KEYS
- INIT_LIST_HEAD(&ns->keyring_name_list);
- init_rwsem(&ns->keyring_sem);
- #endif
- ret = -ENOMEM;
- if (!setup_userns_sysctls(ns))
- goto fail_keyring;
- set_cred_user_ns(new, ns);
- return 0;
- fail_keyring:
- #ifdef CONFIG_PERSISTENT_KEYRINGS
- key_put(ns->persistent_keyring_register);
- #endif
- ns_free_inum(&ns->ns);
- fail_free:
- kmem_cache_free(user_ns_cachep, ns);
- fail_dec:
- dec_user_namespaces(ucounts);
- fail:
- return ret;
- }
- int unshare_userns(unsigned long unshare_flags, struct cred **new_cred)
- {
- struct cred *cred;
- int err = -ENOMEM;
- if (!(unshare_flags & CLONE_NEWUSER))
- return 0;
- cred = prepare_creds();
- if (cred) {
- err = create_user_ns(cred);
- if (err)
- put_cred(cred);
- else
- *new_cred = cred;
- }
- return err;
- }
- static void free_user_ns(struct work_struct *work)
- {
- struct user_namespace *parent, *ns =
- container_of(work, struct user_namespace, work);
- do {
- struct ucounts *ucounts = ns->ucounts;
- parent = ns->parent;
- 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);
- }
- retire_userns_sysctls(ns);
- key_free_user_ns(ns);
- ns_free_inum(&ns->ns);
- kmem_cache_free(user_ns_cachep, ns);
- dec_user_namespaces(ucounts);
- ns = parent;
- } while (refcount_dec_and_test(&parent->ns.count));
- }
- void __put_user_ns(struct user_namespace *ns)
- {
- schedule_work(&ns->work);
- }
- EXPORT_SYMBOL(__put_user_ns);
- /**
- * 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;
- id2 = key->id + key->count - 1;
- /* 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.
- */
- static struct uid_gid_extent *
- map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
- {
- struct idmap_key key;
- key.map_up = false;
- key.count = count;
- key.id = id;
- return bsearch(&key, map->forward, extents,
- sizeof(struct uid_gid_extent), cmp_map_id);
- }
- /**
- * 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.
- */
- static struct uid_gid_extent *
- map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
- {
- unsigned idx;
- u32 first, last, id2;
- id2 = id + count - 1;
- /* Find the matching extent */
- 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))
- return &map->extent[idx];
- }
- return NULL;
- }
- static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count)
- {
- struct uid_gid_extent *extent;
- unsigned extents = map->nr_extents;
- smp_rmb();
- if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
- extent = map_id_range_down_base(extents, map, id, count);
- else
- extent = map_id_range_down_max(extents, map, id, count);
- /* Map the id or note failure */
- if (extent)
- id = (id - extent->first) + extent->lower_first;
- else
- id = (u32) -1;
- return id;
- }
- static u32 map_id_down(struct uid_gid_map *map, u32 id)
- {
- return map_id_range_down(map, id, 1);
- }
- /**
- * 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.
- */
- static struct uid_gid_extent *
- map_id_up_base(unsigned extents, struct uid_gid_map *map, u32 id)
- {
- unsigned idx;
- u32 first, last;
- /* Find the matching extent */
- for (idx = 0; idx < extents; idx++) {
- first = map->extent[idx].lower_first;
- last = first + map->extent[idx].count - 1;
- if (id >= first && id <= last)
- return &map->extent[idx];
- }
- return NULL;
- }
- /**
- * 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.
- */
- static struct uid_gid_extent *
- map_id_up_max(unsigned extents, struct uid_gid_map *map, u32 id)
- {
- struct idmap_key key;
- key.map_up = true;
- key.count = 1;
- key.id = id;
- return bsearch(&key, map->reverse, extents,
- sizeof(struct uid_gid_extent), cmp_map_id);
- }
- static u32 map_id_up(struct uid_gid_map *map, u32 id)
- {
- struct uid_gid_extent *extent;
- unsigned extents = map->nr_extents;
- smp_rmb();
- 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);
- /* Map the id or note failure */
- if (extent)
- id = (id - extent->lower_first) + extent->first;
- 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
- * for and handle INVALID_UID being returned. INVALID_UID
- * 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
- * @gid: group identifier
- *
- * 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);
- /**
- * 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 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);
- 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);
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