76 lines
1.6 KiB
C
76 lines
1.6 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/module.h>
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#include <linux/version.h>
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#include <linux/nsproxy.h>
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#include <linux/user_namespace.h>
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/*
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* Clone a new ns copying an original user ns, setting refcount to 1
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* @old_ns: namespace to clone
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* Return NULL on error (failure to kmalloc), new ns otherwise
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*/
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static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
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{
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struct user_namespace *ns;
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struct user_struct *new_user;
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int n;
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ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
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if (!ns)
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return ERR_PTR(-ENOMEM);
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kref_init(&ns->kref);
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for (n = 0; n < UIDHASH_SZ; ++n)
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INIT_HLIST_HEAD(ns->uidhash_table + n);
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/* Insert new root user. */
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ns->root_user = alloc_uid(ns, 0);
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if (!ns->root_user) {
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kfree(ns);
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return ERR_PTR(-ENOMEM);
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}
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/* Reset current->user with a new one */
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new_user = alloc_uid(ns, current->uid);
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if (!new_user) {
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free_uid(ns->root_user);
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kfree(ns);
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return ERR_PTR(-ENOMEM);
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}
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switch_uid(new_user);
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return ns;
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}
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struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
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{
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struct user_namespace *new_ns;
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BUG_ON(!old_ns);
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get_user_ns(old_ns);
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if (!(flags & CLONE_NEWUSER))
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return old_ns;
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new_ns = clone_user_ns(old_ns);
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put_user_ns(old_ns);
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return new_ns;
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}
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void free_user_ns(struct kref *kref)
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{
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struct user_namespace *ns;
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ns = container_of(kref, struct user_namespace, kref);
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release_uids(ns);
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kfree(ns);
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}
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