From: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Kirill Tkhai <ktkhai-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
Cc: serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org,
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Subject: Re: [PATCH 2/2] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy
Date: Wed, 26 Apr 2017 17:53:53 +0200 [thread overview]
Message-ID: <20170426155352.GA12131@redhat.com> (raw)
In-Reply-To: <149245057248.17600.1341652606136269734.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
On 04/17, Kirill Tkhai wrote:
>
> +struct pidns_ioc_req {
> +/* Set vector of last pids in namespace hierarchy */
> +#define PIDNS_REQ_SET_LAST_PID_VEC 0x1
> + unsigned int req;
> + void __user *data;
> + unsigned int data_size;
> + char std_fields[0];
> +};
see below,
> +static long set_last_pid_vec(struct pid_namespace *pid_ns,
> + struct pidns_ioc_req *req)
> +{
> + char *str, *p;
> + int ret = 0;
> + pid_t pid;
> +
> + read_lock(&tasklist_lock);
> + if (!pid_ns->child_reaper)
> + ret = -EINVAL;
> + read_unlock(&tasklist_lock);
> + if (ret)
> + return ret;
why do you need to check ->child_reaper under tasklist_lock? this looks pointless.
In fact I do not understand how it is possible to hit pid_ns->child_reaper == NULL,
there must be at least one task in this namespace, otherwise you can't open a file
which has f_op == ns_file_operations, no?
> + if (req->data_size >= PAGE_SIZE)
> + return -EINVAL;
> + str = vmalloc(req->data_size + 1);
then I don't understand why it makes sense to use vmalloc()
> + if (!str)
> + return -ENOMEM;
> + if (copy_from_user(str, req->data, req->data_size)) {
> + ret = -EFAULT;
> + goto out_vfree;
> + }
> + str[req->data_size] = '\0';
> +
> + p = str;
> + while (p && *p != '\0') {
> + if (!ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN)) {
> + ret = -EPERM;
> + goto out_vfree;
> + }
> +
> + if (sscanf(p, "%d", &pid) != 1 || pid < 0 || pid > pid_max) {
> + ret = -EINVAL;
> + goto out_vfree;
> + }
Well, this is ioctl(), do we really want to parse the strings?
Can't we make
struct pidns_ioc_req {
...
int nr_pids;
pid_t pids[0];
}
and just use get_user() in a loop? This way we can avoid vmalloc() or anything
else altogether.
Oleg.
next prev parent reply other threads:[~2017-04-26 15:53 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-17 17:34 [PATCH 0/2] nsfs: Introduce ioctl to set vector of ns_last_pid's on pid ns hierarhy Kirill Tkhai
[not found] ` <149245014695.17600.12640895883798122726.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-04-17 17:36 ` [PATCH 1/2] nsfs: Add namespace-specific ioctl (NS_SPECIFIC_IOC) Kirill Tkhai
2017-04-17 17:36 ` [PATCH 2/2] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy Kirill Tkhai
[not found] ` <149245057248.17600.1341652606136269734.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-04-19 20:27 ` Serge E. Hallyn
2017-04-24 19:03 ` Cyrill Gorcunov
2017-04-26 15:53 ` Oleg Nesterov [this message]
[not found] ` <20170426155352.GA12131-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-04-26 16:11 ` Kirill Tkhai
[not found] ` <785e1986-da03-72aa-06c0-234ed2dbc0fd-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-26 16:33 ` Kirill Tkhai
[not found] ` <005f52d9-efbe-9eaa-7f36-19945c8b06c3-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-26 16:32 ` Eric W. Biederman
[not found] ` <87h91bcep5.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-26 16:43 ` Kirill Tkhai
2017-04-26 17:01 ` Eric W. Biederman
2017-04-27 16:12 ` Oleg Nesterov
2017-04-27 16:17 ` Kirill Tkhai
[not found] ` <fdd61d9c-6f88-1669-4d12-31748395fe99-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-27 16:22 ` Oleg Nesterov
2017-04-28 9:17 ` Kirill Tkhai
2017-05-02 16:33 ` Oleg Nesterov
[not found] ` <20170502163324.GA25036-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-05-02 17:22 ` Eric W. Biederman
2017-05-02 17:33 ` Kirill Tkhai
[not found] ` <de392430-18b8-d296-b868-82fdedcd0c0e-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-05-02 21:13 ` Eric W. Biederman
[not found] ` <8737cngdxi.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-05-03 10:20 ` Kirill Tkhai
2017-04-27 16:39 ` Eric W. Biederman
[not found] ` <87o9vhztwv.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-28 9:22 ` Kirill Tkhai
2017-04-27 16:16 ` Oleg Nesterov
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