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| 2 | * Copyright (C) 2004 IBM Corporation
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| 3 | *
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| 4 | * Author: Serge Hallyn <[email protected]>
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| 5 | *
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| 6 | * This program is free software; you can redistribute it and/or
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| 7 | * modify it under the terms of the GNU General Public License as
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| 8 | * published by the Free Software Foundation, version 2 of the
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| 9 | * License.
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| 10 |
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| 11 |
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| 12 | #include <linux/module.h>
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| 13 | #include <linux/uts.h>
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| 14 | #include <linux/utsname.h>
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| 15 | #include <linux/err.h>
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| 16 | #include <linux/slab.h>
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| 17 |
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| 18 | static struct uts_namespace *create_uts_ns(void)
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| 19 | {
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| 20 | struct uts_namespace *uts_ns;
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| 21 |
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| 22 | uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
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| 23 | if (uts_ns)
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| 24 | kref_init(&uts_ns->kref);
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| 25 | return uts_ns;
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| 26 | }
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| 27 |
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| 28 | |
| 29 | * Clone a new ns copying an original utsname, setting refcount to 1
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| 30 | * @old_ns: namespace to clone
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| 31 | * Return NULL on error (failure to kmalloc), new ns otherwise
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| 32 |
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| 33 | static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
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| 34 | {
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| 35 | struct uts_namespace *ns;
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| 36 |
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| 37 | ns = create_uts_ns();
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| 38 | if (!ns)
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| 39 | return ERR_PTR(-ENOMEM);
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| 40 |
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| 41 | down_read(&uts_sem);
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| 42 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
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| 43 | up_read(&uts_sem);
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| 44 | return ns;
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| 45 | }
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| 46 |
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| 47 | |
| 48 | * Copy task tsk's utsname namespace, or clone it if flags
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| 49 | * specifies CLONE_NEWUTS. In latter case, changes to the
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| 50 | * utsname of this process won't be seen by parent, and vice
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| 51 | * versa.
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| 52 |
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| 53 | struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns)
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| 54 | {
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| 55 | struct uts_namespace *new_ns;
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| 56 |
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| 57 | BUG_ON(!old_ns);
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| 58 | get_uts_ns(old_ns);
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| 59 |
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| 60 | if (!(flags & CLONE_NEWUTS))
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| 61 | return old_ns;
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| 62 |
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| 63 | new_ns = clone_uts_ns(old_ns);
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| 64 |
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| 65 | put_uts_ns(old_ns);
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| 66 | return new_ns;
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| 67 | }
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| 68 |
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| 69 | void free_uts_ns(struct kref *kref)
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| 70 | {
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| 71 | struct uts_namespace *ns;
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| 72 |
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| 73 | ns = container_of(kref, struct uts_namespace, kref);
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| 74 | kfree(ns);
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| 75 | }
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