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Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace [message #41774 is a reply to message #41747]

Fri, 18 February 2011 16:57

Daniel Lezcano
Messages: 417
Registered: June 2006

Senior Member

On 02/17/2011 04:02 PM, Serge E. Hallyn wrote:
> copy_process() handles CLONE_NEWUSER before the rest of the
> namespaces. So in the case of clone(CLONE_NEWUSER|CLONE_NEWUTS)
> the new uts namespace will have the new user namespace as its
> owner. That is what we want, since we want root in that new
> userns to be able to have privilege over it.
>
> Changelog:
> Feb 15: don't set uts_ns->user_ns if we didn't create
> a new uts_ns.
>
> Signed-off-by: Serge E. Hallyn<serge.hallyn@canonical.com>

Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>

A couple of comments.

> ---
> include/linux/utsname.h | 3 +++
> init/version.c | 2 ++
> kernel/nsproxy.c | 5 +++++
> kernel/user.c | 8 ++++++--
> kernel/utsname.c | 4 ++++
> 5 files changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/utsname.h b/include/linux/utsname.h
> index 69f3997..85171be 100644
> --- a/include/linux/utsname.h
> +++ b/include/linux/utsname.h
> @@ -37,9 +37,12 @@ struct new_utsname {
> #include<linux/nsproxy.h>
> #include<linux/err.h>
>
> +struct user_namespace;
> +
> struct uts_namespace {
> struct kref kref;
> struct new_utsname name;
> + struct user_namespace *user_ns;
> };
> extern struct uts_namespace init_uts_ns;
>
> diff --git a/init/version.c b/init/version.c
> index adff586..97bb86f 100644
> --- a/init/version.c
> +++ b/init/version.c
> @@ -21,6 +21,7 @@ extern int version_string(LINUX_VERSION_CODE);
> int version_string(LINUX_VERSION_CODE);
> #endif
>
> +extern struct user_namespace init_user_ns;
> struct uts_namespace init_uts_ns = {
> .kref = {
> .refcount = ATOMIC_INIT(2),
> @@ -33,6 +34,7 @@ struct uts_namespace init_uts_ns = {
> .machine = UTS_MACHINE,
> .domainname = UTS_DOMAINNAME,
> },
> + .user_ns =&init_user_ns,
> };
> EXPORT_SYMBOL_GPL(init_uts_ns);
>
> diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
> index f74e6c0..034dc2e 100644
> --- a/kernel/nsproxy.c
> +++ b/kernel/nsproxy.c
> @@ -74,6 +74,11 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
> err = PTR_ERR(new_nsp->uts_ns);
> goto out_uts;
> }
> + if (new_nsp->uts_ns != tsk->nsproxy->uts_ns) {
> + put_user_ns(new_nsp->uts_ns->user_ns);
> + new_nsp->uts_ns->user_ns = task_cred_xxx(tsk, user)->user_ns;
> + get_user_ns(new_nsp->uts_ns->user_ns);
> + }

IMO you should add a comment telling this code assume create_user_ns was
called before (via copy_cred).

>
> new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
> if (IS_ERR(new_nsp->ipc_ns)) {

[ ... ]

> static struct uts_namespace *create_uts_ns(void)
> {
> @@ -40,6 +41,8 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
>
> down_read(&uts_sem);
> memcpy(&ns->name,&old_ns->name, sizeof(ns->name));
> + ns->user_ns = old_ns->user_ns;
> + get_user_ns(ns->user_ns);

ns->user_ns = get_user_ns(old_ns->user_ns);

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[Message index]

		userns: targeted capabilities v5 By: serge on Thu, 17 February 2011 15:02
		[PATCH 2/9] security: Make capabilities relative to the user namespace. By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: ebiederm on Fri, 18 February 2011 03:46
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: Daniel Lezcano on Fri, 18 February 2011 23:44
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: David Howells on Wed, 23 February 2011 12:01
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: serge on Wed, 23 February 2011 13:43
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: David Howells on Wed, 23 February 2011 11:40
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: David Howells on Wed, 23 February 2011 16:59
		[PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: serge on Thu, 17 February 2011 15:04
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: ebiederm on Fri, 18 February 2011 01:29
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: serge on Thu, 24 February 2011 03:24
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: akpm on Thu, 24 February 2011 05:08
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: Daniel Lezcano on Sat, 19 February 2011 19:22
		[PATCH 7/9] add a user namespace owner of ipc ns By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 7/9] add a user namespace owner of ipc ns By: ebiederm on Fri, 18 February 2011 03:19
		Re: [PATCH 7/9] add a user namespace owner of ipc ns By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 7/9] add a user namespace owner of ipc ns By: Daniel Lezcano on Sat, 19 February 2011 17:57
		[PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: serge on Thu, 17 February 2011 15:02
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: ebiederm on Fri, 18 February 2011 03:31
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: Daniel Lezcano on Fri, 18 February 2011 16:57
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: David Howells on Wed, 23 February 2011 17:16
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: ebiederm on Wed, 23 February 2011 21:21
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: David Howells on Wed, 23 February 2011 23:19
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: ebiederm on Wed, 23 February 2011 23:54
		[PATCH 3/9] allow sethostname in a container By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 3/9] allow sethostname in a container By: ebiederm on Fri, 18 February 2011 03:05
		Re: [PATCH 3/9] allow sethostname in a container By: Daniel Lezcano on Fri, 18 February 2011 23:46
		[PATCH 4/9] allow killing tasks in your own or child userns By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: ebiederm on Fri, 18 February 2011 03:00
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: serge on Thu, 24 February 2011 00:48
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: akpm on Thu, 24 February 2011 00:54
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: Daniel Lezcano on Sat, 19 February 2011 10:55
		[PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: ebiederm on Fri, 18 February 2011 01:57
		Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: akpm on Sat, 19 February 2011 00:01
		Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: Daniel Lezcano on Sat, 19 February 2011 17:52
		[PATCH 5/9] Allow ptrace from non-init user namespaces By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: ebiederm on Fri, 18 February 2011 02:59
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: serge on Fri, 18 February 2011 04:36
		[PATCH] userns: ptrace: incorporate feedback from Eric By: serge on Thu, 24 February 2011 00:49
		Re: [PATCH] userns: ptrace: incorporate feedback from Eric By: akpm on Thu, 24 February 2011 00:56
		Re: [PATCH] userns: ptrace: incorporate feedback from Eric By: serge on Thu, 24 February 2011 03:15
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: serge on Thu, 24 February 2011 00:43
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: Daniel Lezcano on Sat, 19 February 2011 17:49
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: David Howells on Wed, 23 February 2011 17:05
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: David Howells on Wed, 23 February 2011 17:11
		[PATCH 8/9] user namespaces: convert several capable() calls By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 8/9] user namespaces: convert several capable() calls By: ebiederm on Fri, 18 February 2011 01:51
		Re: [PATCH 8/9] user namespaces: convert several capable() calls By: Daniel Lezcano on Sat, 19 February 2011 19:07
		Re: userns: targeted capabilities v5 By: akpm on Fri, 18 February 2011 00:21
		Re: userns: targeted capabilities v5 By: ebiederm on Fri, 18 February 2011 03:53
		Re: userns: targeted capabilities v5 By: serge on Fri, 18 February 2011 04:28
		User namespaces and keys By: David Howells on Wed, 23 February 2011 12:05
		Re: User namespaces and keys By: serge on Wed, 23 February 2011 13:58
		Re: User namespaces and keys By: ebiederm on Wed, 23 February 2011 14:46
		Re: User namespaces and keys By: David Howells on Wed, 23 February 2011 15:06
		Re: User namespaces and keys By: ebiederm on Wed, 23 February 2011 15:45
		Re: User namespaces and keys By: Serge E. Hallyn on Wed, 23 February 2011 15:53
		Re: User namespaces and keys By: Casey Schaufler on Wed, 23 February 2011 19:24
		Re: User namespaces and keys By: ebiederm on Wed, 23 February 2011 20:55
		Re: User namespaces and keys By: Casey Schaufler on Wed, 23 February 2011 21:37
		Re: User namespaces and keys By: ebiederm on Thu, 24 February 2011 06:56

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