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Re: [PATCH 5/9] Allow ptrace from non-init user namespaces [message #41781 is a reply to message #41751]

Fri, 18 February 2011 23:59

akpm
Messages: 224
Registered: March 2007

Senior Member

On Thu, 17 Feb 2011 15:03:33 +0000
"Serge E. Hallyn" <serge@hallyn.com> wrote:

> ptrace is allowed to tasks in the same user namespace according to
> the usual rules (i.e. the same rules as for two tasks in the init
> user namespace). ptrace is also allowed to a user namespace to
> which the current task the has CAP_SYS_PTRACE capability.
>
>
> ...
>
> --- a/include/linux/capability.h
> +++ b/include/linux/capability.h
> @@ -546,6 +546,8 @@ extern const kernel_cap_t __cap_init_eff_set;
> */
> #define has_capability(t, cap) (security_real_capable((t), &init_user_ns, (cap)) == 0)
>
> +#define has_ns_capability(t, ns, cap) (security_real_capable((t), (ns), (cap)) == 0)

macroitis.

> /**
> * has_capability_noaudit - Determine if a task has a superior capability available (unaudited)
> * @t: The task in question
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index faf4679..862fc59 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -39,6 +39,9 @@ static inline void put_user_ns(struct user_namespace *ns)
> uid_t user_ns_map_uid(struct user_namespace *to, const struct cred *cred, uid_t uid);
> gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t gid);
>
> +int same_or_ancestor_user_ns(struct task_struct *task,
> + struct task_struct *victim);

bool.

> #else
>
> static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
>
> ...
>
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -129,6 +129,22 @@ gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t
> return overflowgid;
> }
>
> +int same_or_ancestor_user_ns(struct task_struct *task,
> + struct task_struct *victim)
> +{
> + struct user_namespace *u1 = task_cred_xxx(task, user)->user_ns;
> + struct user_namespace *u2 = task_cred_xxx(victim, user)->user_ns;
> + for (;;) {
> + if (u1 == u2)
> + return 1;
> + if (u1 == &init_user_ns)
> + return 0;
> + u1 = u1->creator->user_ns;
> + }
> + /* We never get here */
> + return 0;

Remove?

> +}
> +
> static __init int user_namespaces_init(void)
> {
> user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
>
> ...
>
> int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
> {
> int ret = 0;
> + const struct cred *cred, *tcred;
>
> rcu_read_lock();
> - if (!cap_issubset(__task_cred(child)->cap_permitted,
> - current_cred()->cap_permitted) &&
> - !capable(CAP_SYS_PTRACE))
> - ret = -EPERM;
> + cred = current_cred();
> + tcred = __task_cred(child);
> + /*
> + * The ancestor user_ns check may be gratuitous, as I think
> + * we've already guaranteed that in kernel/ptrace.c.
> + */

?

> + if (same_or_ancestor_user_ns(current, child) &&
> + cap_issubset(tcred->cap_permitted, cred->cap_permitted))
> + goto out;
> + if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
> + goto out;
> + ret = -EPERM;
> +out:
> rcu_read_unlock();
> return ret;
> }
>
> ...
>

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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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