#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,
if (!ns)
return -ENOMEM;
- ret = proc_alloc_inum(&ns->proc_inum);
+ 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->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
#ifdef CONFIG_PERSISTENT_KEYRINGS
key_put(ns->persistent_keyring_register);
#endif
- proc_free_inum(ns->proc_inum);
+ ns_free_inum(&ns->ns);
kmem_cache_free(user_ns_cachep, ns);
ns = parent;
} while (atomic_dec_and_test(&parent->count));
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,
ssize_t ret = -EINVAL;
/*
- * The id_map_mutex serializes all writes to any given map.
+ * The userns_state_mutex serializes all writes to any given map.
*
* Any map is only ever written once.
*
* order and smp_rmb() is guaranteed that we don't have crazy
* architectures returning stale data.
*/
- mutex_lock(&id_map_mutex);
+ mutex_lock(&userns_state_mutex);
ret = -EPERM;
/* Only allow one successful write to the map */
if (!page)
goto out;
- /* Only allow <= page size writes at the beginning of the file */
+ /* Only allow < page size writes at the beginning of the file */
ret = -EINVAL;
if ((*ppos != 0) || (count >= PAGE_SIZE))
goto out;
*ppos = count;
ret = count;
out:
- mutex_unlock(&id_map_mutex);
+ mutex_unlock(&userns_state_mutex);
if (page)
free_page(page);
return ret;
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)) {
+ 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, file->f_cred->fsuid))
+ if (uid_eq(uid, cred->euid))
return true;
} else if (cap_setid == CAP_SETGID) {
kgid_t gid = make_kgid(ns->parent, id);
- if (gid_eq(gid, file->f_cred->fsgid))
+ if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) &&
+ gid_eq(gid, cred->egid))
return true;
}
}
return false;
}
-static void *userns_get(struct task_struct *task)
+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;
user_ns = get_user_ns(__task_cred(task)->user_ns);
rcu_read_unlock();
- return user_ns;
+ return user_ns ? &user_ns->ns : NULL;
}
-static void userns_put(void *ns)
+static void userns_put(struct ns_common *ns)
{
- put_user_ns(ns);
+ put_user_ns(to_user_ns(ns));
}
-static int userns_install(struct nsproxy *nsproxy, void *ns)
+static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns)
{
- struct user_namespace *user_ns = ns;
+ struct user_namespace *user_ns = to_user_ns(ns);
struct cred *cred;
/* Don't allow gaining capabilities by reentering
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)
projects / cascardo / linux.git / blobdiff