5c1469de75
Define what happens when a we view a uid from one user_namespace in another user_namepece. - If the user namespaces are the same no mapping is necessary. - For most cases of difference use overflowuid and overflowgid, the uid and gid currently used for 16bit apis when we have a 32bit uid that does fit in 16bits. Effectively the situation is the same, we want to return a uid or gid that is not assigned to any user. - For the case when we happen to be mapping the uid or gid of the creator of the target user namespace use uid 0 and gid as confusing that user with root is not a problem. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Serge E. Hallyn <serue@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
129 lines
3.2 KiB
C
129 lines
3.2 KiB
C
/*
|
|
* 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/module.h>
|
|
#include <linux/nsproxy.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/user_namespace.h>
|
|
#include <linux/highuid.h>
|
|
#include <linux/cred.h>
|
|
|
|
/*
|
|
* 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;
|
|
struct user_struct *root_user;
|
|
int n;
|
|
|
|
ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
|
|
if (!ns)
|
|
return -ENOMEM;
|
|
|
|
kref_init(&ns->kref);
|
|
|
|
for (n = 0; n < UIDHASH_SZ; ++n)
|
|
INIT_HLIST_HEAD(ns->uidhash_table + n);
|
|
|
|
/* Alloc new root user. */
|
|
root_user = alloc_uid(ns, 0);
|
|
if (!root_user) {
|
|
kfree(ns);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* set the new root user in the credentials under preparation */
|
|
ns->creator = new->user;
|
|
new->user = root_user;
|
|
new->uid = new->euid = new->suid = new->fsuid = 0;
|
|
new->gid = new->egid = new->sgid = new->fsgid = 0;
|
|
put_group_info(new->group_info);
|
|
new->group_info = get_group_info(&init_groups);
|
|
#ifdef CONFIG_KEYS
|
|
key_put(new->request_key_auth);
|
|
new->request_key_auth = NULL;
|
|
#endif
|
|
/* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
|
|
|
|
/* root_user holds a reference to ns, our reference can be dropped */
|
|
put_user_ns(ns);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Deferred destructor for a user namespace. This is required because
|
|
* free_user_ns() may be called with uidhash_lock held, but we need to call
|
|
* back to free_uid() which will want to take the lock again.
|
|
*/
|
|
static void free_user_ns_work(struct work_struct *work)
|
|
{
|
|
struct user_namespace *ns =
|
|
container_of(work, struct user_namespace, destroyer);
|
|
free_uid(ns->creator);
|
|
kfree(ns);
|
|
}
|
|
|
|
void free_user_ns(struct kref *kref)
|
|
{
|
|
struct user_namespace *ns =
|
|
container_of(kref, struct user_namespace, kref);
|
|
|
|
INIT_WORK(&ns->destroyer, free_user_ns_work);
|
|
schedule_work(&ns->destroyer);
|
|
}
|
|
EXPORT_SYMBOL(free_user_ns);
|
|
|
|
uid_t user_ns_map_uid(struct user_namespace *to, const struct cred *cred, uid_t uid)
|
|
{
|
|
struct user_namespace *tmp;
|
|
|
|
if (likely(to == cred->user->user_ns))
|
|
return uid;
|
|
|
|
|
|
/* Is cred->user the creator of the target user_ns
|
|
* or the creator of one of it's parents?
|
|
*/
|
|
for ( tmp = to; tmp != &init_user_ns;
|
|
tmp = tmp->creator->user_ns ) {
|
|
if (cred->user == tmp->creator) {
|
|
return (uid_t)0;
|
|
}
|
|
}
|
|
|
|
/* No useful relationship so no mapping */
|
|
return overflowuid;
|
|
}
|
|
|
|
gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t gid)
|
|
{
|
|
struct user_namespace *tmp;
|
|
|
|
if (likely(to == cred->user->user_ns))
|
|
return gid;
|
|
|
|
/* Is cred->user the creator of the target user_ns
|
|
* or the creator of one of it's parents?
|
|
*/
|
|
for ( tmp = to; tmp != &init_user_ns;
|
|
tmp = tmp->creator->user_ns ) {
|
|
if (cred->user == tmp->creator) {
|
|
return (gid_t)0;
|
|
}
|
|
}
|
|
|
|
/* No useful relationship so no mapping */
|
|
return overflowgid;
|
|
}
|