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![David Howells](/assets/img/avatar_default.png)
Add support for per-user_namespace registers of persistent per-UID kerberos caches held within the kernel. This allows the kerberos cache to be retained beyond the life of all a user's processes so that the user's cron jobs can work. The kerberos cache is envisioned as a keyring/key tree looking something like: struct user_namespace \___ .krb_cache keyring - The register \___ _krb.0 keyring - Root's Kerberos cache \___ _krb.5000 keyring - User 5000's Kerberos cache \___ _krb.5001 keyring - User 5001's Kerberos cache \___ tkt785 big_key - A ccache blob \___ tkt12345 big_key - Another ccache blob Or possibly: struct user_namespace \___ .krb_cache keyring - The register \___ _krb.0 keyring - Root's Kerberos cache \___ _krb.5000 keyring - User 5000's Kerberos cache \___ _krb.5001 keyring - User 5001's Kerberos cache \___ tkt785 keyring - A ccache \___ krbtgt/REDHAT.COM@REDHAT.COM big_key \___ http/REDHAT.COM@REDHAT.COM user \___ afs/REDHAT.COM@REDHAT.COM user \___ nfs/REDHAT.COM@REDHAT.COM user \___ krbtgt/KERNEL.ORG@KERNEL.ORG big_key \___ http/KERNEL.ORG@KERNEL.ORG big_key What goes into a particular Kerberos cache is entirely up to userspace. Kernel support is limited to giving you the Kerberos cache keyring that you want. The user asks for their Kerberos cache by: krb_cache = keyctl_get_krbcache(uid, dest_keyring); The uid is -1 or the user's own UID for the user's own cache or the uid of some other user's cache (requires CAP_SETUID). This permits rpc.gssd or whatever to mess with the cache. The cache returned is a keyring named "_krb.<uid>" that the possessor can read, search, clear, invalidate, unlink from and add links to. Active LSMs get a chance to rule on whether the caller is permitted to make a link. Each uid's cache keyring is created when it first accessed and is given a timeout that is extended each time this function is called so that the keyring goes away after a while. The timeout is configurable by sysctl but defaults to three days. Each user_namespace struct gets a lazily-created keyring that serves as the register. The cache keyrings are added to it. This means that standard key search and garbage collection facilities are available. The user_namespace struct's register goes away when it does and anything left in it is then automatically gc'd. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Simo Sorce <simo@redhat.com> cc: Serge E. Hallyn <serge.hallyn@ubuntu.com> cc: Eric W. Biederman <ebiederm@xmission.com>
905 lines
23 KiB
C
905 lines
23 KiB
C
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*/
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#include <linux/export.h>
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#include <linux/nsproxy.h>
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#include <linux/slab.h>
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#include <linux/user_namespace.h>
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#include <linux/proc_ns.h>
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#include <linux/highuid.h>
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#include <linux/cred.h>
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#include <linux/securebits.h>
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#include <linux/keyctl.h>
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#include <linux/key-type.h>
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#include <keys/user-type.h>
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#include <linux/seq_file.h>
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#include <linux/fs.h>
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#include <linux/uaccess.h>
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#include <linux/ctype.h>
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#include <linux/projid.h>
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#include <linux/fs_struct.h>
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static struct kmem_cache *user_ns_cachep __read_mostly;
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static bool new_idmap_permitted(const struct file *file,
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struct user_namespace *ns, int cap_setid,
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struct uid_gid_map *map);
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static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns)
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{
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/* Start with the same capabilities as init but useless for doing
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* anything as the capabilities are bound to the new user namespace.
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*/
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cred->securebits = SECUREBITS_DEFAULT;
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cred->cap_inheritable = CAP_EMPTY_SET;
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cred->cap_permitted = CAP_FULL_SET;
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cred->cap_effective = CAP_FULL_SET;
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cred->cap_bset = CAP_FULL_SET;
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#ifdef CONFIG_KEYS
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key_put(cred->request_key_auth);
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cred->request_key_auth = NULL;
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#endif
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/* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
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cred->user_ns = user_ns;
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}
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/*
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* Create a new user namespace, deriving the creator from the user in the
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* passed credentials, and replacing that user with the new root user for the
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* new namespace.
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*
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* This is called by copy_creds(), which will finish setting the target task's
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* credentials.
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*/
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int create_user_ns(struct cred *new)
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{
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struct user_namespace *ns, *parent_ns = new->user_ns;
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kuid_t owner = new->euid;
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kgid_t group = new->egid;
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int ret;
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if (parent_ns->level > 32)
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return -EUSERS;
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/*
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* Verify that we can not violate the policy of which files
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* may be accessed that is specified by the root directory,
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* by verifing that the root directory is at the root of the
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* mount namespace which allows all files to be accessed.
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*/
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if (current_chrooted())
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return -EPERM;
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/* The creator needs a mapping in the parent user namespace
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* or else we won't be able to reasonably tell userspace who
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* created a user_namespace.
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*/
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if (!kuid_has_mapping(parent_ns, owner) ||
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!kgid_has_mapping(parent_ns, group))
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return -EPERM;
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ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL);
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if (!ns)
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return -ENOMEM;
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ret = proc_alloc_inum(&ns->proc_inum);
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if (ret) {
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kmem_cache_free(user_ns_cachep, ns);
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return ret;
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}
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atomic_set(&ns->count, 1);
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/* Leave the new->user_ns reference with the new user namespace. */
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ns->parent = parent_ns;
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ns->level = parent_ns->level + 1;
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ns->owner = owner;
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ns->group = group;
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set_cred_user_ns(new, ns);
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#ifdef CONFIG_PERSISTENT_KEYRINGS
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init_rwsem(&ns->persistent_keyring_register_sem);
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#endif
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return 0;
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}
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int unshare_userns(unsigned long unshare_flags, struct cred **new_cred)
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{
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struct cred *cred;
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int err = -ENOMEM;
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if (!(unshare_flags & CLONE_NEWUSER))
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return 0;
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cred = prepare_creds();
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if (cred) {
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err = create_user_ns(cred);
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if (err)
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put_cred(cred);
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else
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*new_cred = cred;
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}
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return err;
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}
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void free_user_ns(struct user_namespace *ns)
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{
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struct user_namespace *parent;
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do {
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parent = ns->parent;
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#ifdef CONFIG_PERSISTENT_KEYRINGS
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key_put(ns->persistent_keyring_register);
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#endif
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proc_free_inum(ns->proc_inum);
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kmem_cache_free(user_ns_cachep, ns);
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ns = parent;
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} while (atomic_dec_and_test(&parent->count));
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}
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EXPORT_SYMBOL(free_user_ns);
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static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count)
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{
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unsigned idx, extents;
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u32 first, last, id2;
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id2 = id + count - 1;
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/* Find the matching extent */
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extents = map->nr_extents;
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smp_read_barrier_depends();
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for (idx = 0; idx < extents; idx++) {
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first = map->extent[idx].first;
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last = first + map->extent[idx].count - 1;
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if (id >= first && id <= last &&
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(id2 >= first && id2 <= last))
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break;
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}
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/* Map the id or note failure */
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if (idx < extents)
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id = (id - first) + map->extent[idx].lower_first;
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else
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id = (u32) -1;
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return id;
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}
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static u32 map_id_down(struct uid_gid_map *map, u32 id)
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{
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unsigned idx, extents;
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u32 first, last;
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/* Find the matching extent */
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extents = map->nr_extents;
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smp_read_barrier_depends();
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for (idx = 0; idx < extents; idx++) {
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first = map->extent[idx].first;
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last = first + map->extent[idx].count - 1;
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if (id >= first && id <= last)
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break;
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}
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/* Map the id or note failure */
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if (idx < extents)
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id = (id - first) + map->extent[idx].lower_first;
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else
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id = (u32) -1;
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return id;
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}
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static u32 map_id_up(struct uid_gid_map *map, u32 id)
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{
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unsigned idx, extents;
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u32 first, last;
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/* Find the matching extent */
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extents = map->nr_extents;
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smp_read_barrier_depends();
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for (idx = 0; idx < extents; idx++) {
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first = map->extent[idx].lower_first;
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last = first + map->extent[idx].count - 1;
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if (id >= first && id <= last)
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break;
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}
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/* Map the id or note failure */
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if (idx < extents)
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id = (id - first) + map->extent[idx].first;
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else
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id = (u32) -1;
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return id;
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}
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/**
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* make_kuid - Map a user-namespace uid pair into a kuid.
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* @ns: User namespace that the uid is in
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* @uid: User identifier
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*
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* Maps a user-namespace uid pair into a kernel internal kuid,
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* and returns that kuid.
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*
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* When there is no mapping defined for the user-namespace uid
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* pair INVALID_UID is returned. Callers are expected to test
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* for and handle handle INVALID_UID being returned. INVALID_UID
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* may be tested for using uid_valid().
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*/
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kuid_t make_kuid(struct user_namespace *ns, uid_t uid)
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{
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/* Map the uid to a global kernel uid */
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return KUIDT_INIT(map_id_down(&ns->uid_map, uid));
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}
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EXPORT_SYMBOL(make_kuid);
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/**
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* from_kuid - Create a uid from a kuid user-namespace pair.
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* @targ: The user namespace we want a uid in.
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* @kuid: The kernel internal uid to start with.
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*
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* Map @kuid into the user-namespace specified by @targ and
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* return the resulting uid.
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*
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* There is always a mapping into the initial user_namespace.
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*
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* If @kuid has no mapping in @targ (uid_t)-1 is returned.
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*/
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uid_t from_kuid(struct user_namespace *targ, kuid_t kuid)
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{
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/* Map the uid from a global kernel uid */
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return map_id_up(&targ->uid_map, __kuid_val(kuid));
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}
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EXPORT_SYMBOL(from_kuid);
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/**
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* from_kuid_munged - Create a uid from a kuid user-namespace pair.
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* @targ: The user namespace we want a uid in.
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* @kuid: The kernel internal uid to start with.
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*
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* Map @kuid into the user-namespace specified by @targ and
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* return the resulting uid.
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*
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* There is always a mapping into the initial user_namespace.
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*
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* Unlike from_kuid from_kuid_munged never fails and always
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* returns a valid uid. This makes from_kuid_munged appropriate
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* for use in syscalls like stat and getuid where failing the
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* system call and failing to provide a valid uid are not an
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* options.
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*
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* If @kuid has no mapping in @targ overflowuid is returned.
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*/
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uid_t from_kuid_munged(struct user_namespace *targ, kuid_t kuid)
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{
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uid_t uid;
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uid = from_kuid(targ, kuid);
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if (uid == (uid_t) -1)
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uid = overflowuid;
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return uid;
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}
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EXPORT_SYMBOL(from_kuid_munged);
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/**
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* make_kgid - Map a user-namespace gid pair into a kgid.
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* @ns: User namespace that the gid is in
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* @uid: group identifier
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*
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* Maps a user-namespace gid pair into a kernel internal kgid,
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* and returns that kgid.
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*
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* When there is no mapping defined for the user-namespace gid
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* pair INVALID_GID is returned. Callers are expected to test
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* for and handle INVALID_GID being returned. INVALID_GID may be
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* tested for using gid_valid().
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*/
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kgid_t make_kgid(struct user_namespace *ns, gid_t gid)
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{
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/* Map the gid to a global kernel gid */
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return KGIDT_INIT(map_id_down(&ns->gid_map, gid));
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}
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EXPORT_SYMBOL(make_kgid);
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/**
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* from_kgid - Create a gid from a kgid user-namespace pair.
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* @targ: The user namespace we want a gid in.
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* @kgid: The kernel internal gid to start with.
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*
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* Map @kgid into the user-namespace specified by @targ and
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* return the resulting gid.
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*
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* There is always a mapping into the initial user_namespace.
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*
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* If @kgid has no mapping in @targ (gid_t)-1 is returned.
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*/
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gid_t from_kgid(struct user_namespace *targ, kgid_t kgid)
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{
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/* Map the gid from a global kernel gid */
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return map_id_up(&targ->gid_map, __kgid_val(kgid));
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}
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EXPORT_SYMBOL(from_kgid);
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/**
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* from_kgid_munged - Create a gid from a kgid user-namespace pair.
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* @targ: The user namespace we want a gid in.
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* @kgid: The kernel internal gid to start with.
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*
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* Map @kgid into the user-namespace specified by @targ and
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* return the resulting gid.
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*
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* There is always a mapping into the initial user_namespace.
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*
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* Unlike from_kgid from_kgid_munged never fails and always
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* returns a valid gid. This makes from_kgid_munged appropriate
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* for use in syscalls like stat and getgid where failing the
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* system call and failing to provide a valid gid are not options.
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*
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* If @kgid has no mapping in @targ overflowgid is returned.
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*/
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gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid)
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{
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gid_t gid;
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gid = from_kgid(targ, kgid);
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if (gid == (gid_t) -1)
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gid = overflowgid;
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return gid;
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}
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EXPORT_SYMBOL(from_kgid_munged);
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/**
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* make_kprojid - Map a user-namespace projid pair into a kprojid.
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* @ns: User namespace that the projid is in
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* @projid: Project identifier
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*
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* Maps a user-namespace uid pair into a kernel internal kuid,
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* and returns that kuid.
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*
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* When there is no mapping defined for the user-namespace projid
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* pair INVALID_PROJID is returned. Callers are expected to test
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* for and handle handle INVALID_PROJID being returned. INVALID_PROJID
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* may be tested for using projid_valid().
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*/
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kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid)
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{
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/* Map the uid to a global kernel uid */
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return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid));
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}
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EXPORT_SYMBOL(make_kprojid);
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/**
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* from_kprojid - Create a projid from a kprojid user-namespace pair.
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* @targ: The user namespace we want a projid in.
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* @kprojid: The kernel internal project identifier to start with.
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*
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* Map @kprojid into the user-namespace specified by @targ and
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* return the resulting projid.
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*
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* There is always a mapping into the initial user_namespace.
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*
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* If @kprojid has no mapping in @targ (projid_t)-1 is returned.
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*/
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projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid)
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{
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/* Map the uid from a global kernel uid */
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return map_id_up(&targ->projid_map, __kprojid_val(kprojid));
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}
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EXPORT_SYMBOL(from_kprojid);
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/**
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* from_kprojid_munged - Create a projiid from a kprojid user-namespace pair.
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* @targ: The user namespace we want a projid in.
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* @kprojid: The kernel internal projid to start with.
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*
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* Map @kprojid into the user-namespace specified by @targ and
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* return the resulting projid.
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*
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* There is always a mapping into the initial user_namespace.
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*
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* Unlike from_kprojid from_kprojid_munged never fails and always
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* returns a valid projid. This makes from_kprojid_munged
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* appropriate for use in syscalls like stat and where
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* failing the system call and failing to provide a valid projid are
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* not an options.
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*
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* If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned.
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*/
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projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid)
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{
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projid_t projid;
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projid = from_kprojid(targ, kprojid);
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if (projid == (projid_t) -1)
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projid = OVERFLOW_PROJID;
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return projid;
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}
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EXPORT_SYMBOL(from_kprojid_munged);
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static int uid_m_show(struct seq_file *seq, void *v)
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{
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struct user_namespace *ns = seq->private;
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struct uid_gid_extent *extent = v;
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struct user_namespace *lower_ns;
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uid_t lower;
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lower_ns = seq_user_ns(seq);
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if ((lower_ns == ns) && lower_ns->parent)
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lower_ns = lower_ns->parent;
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lower = from_kuid(lower_ns, KUIDT_INIT(extent->lower_first));
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seq_printf(seq, "%10u %10u %10u\n",
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extent->first,
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lower,
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extent->count);
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return 0;
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}
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static int gid_m_show(struct seq_file *seq, void *v)
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{
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struct user_namespace *ns = seq->private;
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struct uid_gid_extent *extent = v;
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struct user_namespace *lower_ns;
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gid_t lower;
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lower_ns = seq_user_ns(seq);
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if ((lower_ns == ns) && lower_ns->parent)
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lower_ns = lower_ns->parent;
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lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first));
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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_read_barrier_depends() 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);
|