--- /dev/null
+/*
+ * 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 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 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 = ns_alloc_inum(&ns->ns);
+ if (ret) {
+ kmem_cache_free(user_ns_cachep, ns);
+ return ret;
+ }
+ ns->ns.ops = &userns_operations;
+
+ 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;
+
+ /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
+ mutex_lock(&userns_state_mutex);
+ ns->flags = parent_ns->flags;
+ mutex_unlock(&userns_state_mutex);
+
+ set_cred_user_ns(new, ns);
+
+#ifdef CONFIG_PERSISTENT_KEYRINGS
+ init_rwsem(&ns->persistent_keyring_register_sem);
+#endif
+ 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;
+#ifdef CONFIG_PERSISTENT_KEYRINGS
+ key_put(ns->persistent_keyring_register);
+#endif
+ ns_free_inum(&ns->ns);
+ 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 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 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;
+}
+
+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;
+
+ 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 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 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);
+
+ 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(&userns_state_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)
+{
+ const struct cred *cred = file->f_cred;
+ /* 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 had the approprpiate 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 = ACCESS_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;
+}
+
+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 nsproxy *nsproxy, 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;
+
+ /* 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);
+}
+
+const struct proc_ns_operations userns_operations = {
+ .name = "user",
+ .type = CLONE_NEWUSER,
+ .get = userns_get,
+ .put = userns_put,
+ .install = userns_install,
+};
+
+static __init int user_namespaces_init(void)
+{
+ user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
+ return 0;
+}
+subsys_initcall(user_namespaces_init);
Code Review / kvmfornfv.git / blobdiff