| /* |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License as |
| * published by the Free Software Foundation, version 2 of the |
| * License. |
| */ |
| |
| #include <linux/export.h> |
| #include <linux/nsproxy.h> |
| #include <linux/slab.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/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> |
| |
| static struct kmem_cache *user_ns_cachep __read_mostly; |
| |
| static bool new_idmap_permitted(const struct file *file, |
| struct user_namespace *ns, int cap_setid, |
| struct uid_gid_map *map); |
| |
| 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_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; |
| } |
| |
| /* |
| * 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; |
| int ret; |
| |
| if (parent_ns->level > 32) |
| return -EUSERS; |
| |
| /* |
| * 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. |
| */ |
| if (current_chrooted()) |
| return -EPERM; |
| |
| /* 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. |
| */ |
| if (!kuid_has_mapping(parent_ns, owner) || |
| !kgid_has_mapping(parent_ns, group)) |
| return -EPERM; |
| |
| ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL); |
| if (!ns) |
| return -ENOMEM; |
| |
| ret = proc_alloc_inum(&ns->proc_inum); |
| if (ret) { |
| kmem_cache_free(user_ns_cachep, ns); |
| return ret; |
| } |
| |
| atomic_set(&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; |
| |
| set_cred_user_ns(new, ns); |
| |
| update_mnt_policy(ns); |
| |
| return 0; |
| } |
| |
| 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; |
| } |
| |
| void free_user_ns(struct user_namespace *ns) |
| { |
| struct user_namespace *parent; |
| |
| do { |
| parent = ns->parent; |
| proc_free_inum(ns->proc_inum); |
| kmem_cache_free(user_ns_cachep, ns); |
| ns = parent; |
| } while (atomic_dec_and_test(&parent->count)); |
| } |
| EXPORT_SYMBOL(free_user_ns); |
| |
| static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count) |
| { |
| unsigned idx, extents; |
| u32 first, last, id2; |
| |
| id2 = id + count - 1; |
| |
| /* Find the matching extent */ |
| extents = map->nr_extents; |
| smp_rmb(); |
| 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)) |
| break; |
| } |
| /* Map the id or note failure */ |
| if (idx < extents) |
| id = (id - first) + map->extent[idx].lower_first; |
| else |
| id = (u32) -1; |
| |
| return id; |
| } |
| |
| static u32 map_id_down(struct uid_gid_map *map, u32 id) |
| { |
| unsigned idx, extents; |
| u32 first, last; |
| |
| /* Find the matching extent */ |
| extents = map->nr_extents; |
| smp_rmb(); |
| for (idx = 0; idx < extents; idx++) { |
| first = map->extent[idx].first; |
| last = first + map->extent[idx].count - 1; |
| if (id >= first && id <= last) |
| break; |
| } |
| /* Map the id or note failure */ |
| if (idx < extents) |
| id = (id - first) + map->extent[idx].lower_first; |
| else |
| id = (u32) -1; |
| |
| return id; |
| } |
| |
| static u32 map_id_up(struct uid_gid_map *map, u32 id) |
| { |
| unsigned idx, extents; |
| u32 first, last; |
| |
| /* Find the matching extent */ |
| extents = map->nr_extents; |
| smp_rmb(); |
| for (idx = 0; idx < extents; idx++) { |
| first = map->extent[idx].lower_first; |
| last = first + map->extent[idx].count - 1; |
| if (id >= first && id <= last) |
| break; |
| } |
| /* Map the id or note failure */ |
| if (idx < extents) |
| id = (id - first) + map->extent[idx].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 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 |
| * @uid: 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 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) |
| { |
| struct uid_gid_extent *extent = NULL; |
| loff_t pos = *ppos; |
| |
| if (pos < map->nr_extents) |
| extent = &map->extent[pos]; |
| |
| return extent; |
| } |
| |
| 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; |
| } |
| |
| struct seq_operations proc_uid_seq_operations = { |
| .start = uid_m_start, |
| .stop = m_stop, |
| .next = m_next, |
| .show = uid_m_show, |
| }; |
| |
| struct seq_operations proc_gid_seq_operations = { |
| .start = gid_m_start, |
| .stop = m_stop, |
| .next = m_next, |
| .show = gid_m_show, |
| }; |
| |
| 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; |
| |
| prev = &new_map->extent[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; |
| } |
| |
| |
| static DEFINE_MUTEX(id_map_mutex); |
| |
| 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; |
| struct uid_gid_extent *extent = NULL; |
| unsigned long page = 0; |
| char *kbuf, *pos, *next_line; |
| ssize_t ret = -EINVAL; |
| |
| /* |
| * The id_map_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(&id_map_mutex); |
| |
| 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, ns, CAP_SYS_ADMIN)) |
| goto out; |
| |
| /* Get a buffer */ |
| ret = -ENOMEM; |
| page = __get_free_page(GFP_TEMPORARY); |
| kbuf = (char *) page; |
| if (!page) |
| goto out; |
| |
| /* Only allow <= page size writes at the beginning of the file */ |
| ret = -EINVAL; |
| if ((*ppos != 0) || (count >= PAGE_SIZE)) |
| goto out; |
| |
| /* Slurp in the user data */ |
| ret = -EFAULT; |
| if (copy_from_user(kbuf, buf, count)) |
| goto out; |
| kbuf[count] = '\0'; |
| |
| /* Parse the user data */ |
| ret = -EINVAL; |
| pos = kbuf; |
| new_map.nr_extents = 0; |
| for (;pos; pos = next_line) { |
| extent = &new_map.extent[new_map.nr_extents]; |
| |
| /* 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; |
| |
| new_map.nr_extents++; |
| |
| /* Fail if the file contains too many extents */ |
| if ((new_map.nr_extents == UID_GID_MAP_MAX_EXTENTS) && |
| (next_line != NULL)) |
| goto out; |
| } |
| /* 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. */ |
| if (!new_idmap_permitted(file, ns, cap_setid, &new_map)) |
| goto out; |
| |
| /* Map the lower ids from the parent user namespace to the |
| * kernel global id space. |
| */ |
| for (idx = 0; idx < new_map.nr_extents; idx++) { |
| u32 lower_first; |
| extent = &new_map.extent[idx]; |
| |
| lower_first = map_id_range_down(parent_map, |
| extent->lower_first, |
| extent->count); |
| |
| /* Fail if we can not map the specified extent to |
| * the kernel global id space. |
| */ |
| if (lower_first == (u32) -1) |
| goto out; |
| |
| extent->lower_first = lower_first; |
| } |
| |
| /* Install the map */ |
| memcpy(map->extent, new_map.extent, |
| new_map.nr_extents*sizeof(new_map.extent[0])); |
| smp_wmb(); |
| map->nr_extents = new_map.nr_extents; |
| |
| *ppos = count; |
| ret = count; |
| out: |
| mutex_unlock(&id_map_mutex); |
| if (page) |
| free_page(page); |
| 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) |
| { |
| /* Allow mapping to your own filesystem ids */ |
| if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1)) { |
| 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, file->f_cred->fsuid)) |
| return true; |
| } |
| else if (cap_setid == CAP_SETGID) { |
| kgid_t gid = make_kgid(ns->parent, id); |
| if (gid_eq(gid, file->f_cred->fsgid)) |
| 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 had the approprpiate capability. |
| */ |
| if (ns_capable(ns->parent, cap_setid) && |
| file_ns_capable(file, ns->parent, cap_setid)) |
| return true; |
| |
| return false; |
| } |
| |
| static void *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; |
| } |
| |
| static void userns_put(void *ns) |
| { |
| put_user_ns(ns); |
| } |
| |
| static int userns_install(struct nsproxy *nsproxy, void *ns) |
| { |
| struct user_namespace *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; |
| |
| /* Threaded processes may not enter a different user namespace */ |
| if (atomic_read(¤t->mm->mm_users) > 1) |
| return -EINVAL; |
| |
| if (current->fs->users != 1) |
| return -EINVAL; |
| |
| 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); |
| } |
| |
| static unsigned int userns_inum(void *ns) |
| { |
| struct user_namespace *user_ns = ns; |
| return user_ns->proc_inum; |
| } |
| |
| const struct proc_ns_operations userns_operations = { |
| .name = "user", |
| .type = CLONE_NEWUSER, |
| .get = userns_get, |
| .put = userns_put, |
| .install = userns_install, |
| .inum = userns_inum, |
| }; |
| |
| static __init int user_namespaces_init(void) |
| { |
| user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC); |
| return 0; |
| } |
| module_init(user_namespaces_init); |