| 1 | |
| 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/version.h>
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| 16 |
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| 17 | |
| 18 | * Clone a new ns copying an original utsname, setting refcount to 1
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| 19 | * @old_ns: namespace to clone
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| 20 | * Return NULL on error (failure to kmalloc), new ns otherwise
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| 21 |
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| 22 | static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
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| 23 | {
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| 24 | struct uts_namespace *ns;
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| 25 |
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| 26 | ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
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| 27 | if (ns) {
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| 28 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
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| 29 | kref_init(&ns->kref);
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| 30 | }
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| 31 | return ns;
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| 32 | }
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| 33 |
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| 34 | |
| 35 | * unshare the current process' utsname namespace.
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| 36 | * called only in sys_unshare()
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| 37 |
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| 38 | int unshare_utsname(unsigned long unshare_flags, struct uts_namespace **new_uts)
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| 39 | {
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| 40 | if (unshare_flags & CLONE_NEWUTS) {
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| 41 | if (!capable(CAP_SYS_ADMIN))
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| 42 | return -EPERM;
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| 43 |
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| 44 | *new_uts = clone_uts_ns(current->nsproxy->uts_ns);
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| 45 | if (!*new_uts)
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| 46 | return -ENOMEM;
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| 47 | }
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| 48 |
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| 49 | return 0;
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| 50 | }
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| 51 |
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| 52 | |
| 53 | * Copy task tsk's utsname namespace, or clone it if flags
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| 54 | * specifies CLONE_NEWUTS. In latter case, changes to the
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| 55 | * utsname of this process won't be seen by parent, and vice
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| 56 | * versa.
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| 57 |
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| 58 | int copy_utsname(int flags, struct task_struct *tsk)
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| 59 | {
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| 60 | struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
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| 61 | struct uts_namespace *new_ns;
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| 62 | int err = 0;
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| 63 |
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| 64 | if (!old_ns)
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| 65 | return 0;
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| 66 |
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| 67 | get_uts_ns(old_ns);
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| 68 |
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| 69 | if (!(flags & CLONE_NEWUTS))
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| 70 | return 0;
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| 71 |
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| 72 | if (!capable(CAP_SYS_ADMIN)) {
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| 73 | err = -EPERM;
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| 74 | goto out;
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| 75 | }
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| 76 |
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| 77 | new_ns = clone_uts_ns(old_ns);
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| 78 | if (!new_ns) {
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| 79 | err = -ENOMEM;
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| 80 | goto out;
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| 81 | }
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| 82 | tsk->nsproxy->uts_ns = new_ns;
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| 83 |
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| 84 | out:
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| 85 | put_uts_ns(old_ns);
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| 86 | return err;
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| 87 | }
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| 88 |
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| 89 | void free_uts_ns(struct kref *kref)
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| 90 | {
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| 91 | struct uts_namespace *ns;
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| 92 |
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| 93 | ns = container_of(kref, struct uts_namespace, kref);
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| 94 | kfree(ns);
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| 95 | }
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