| Message ID | 1468249078-6949-1-git-send-email-david.vrabel@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07/11/2016 10:57 AM, David Vrabel wrote: > diff --git a/include/uapi/xen/evtchn.h b/include/uapi/xen/evtchn.h > index 14e833ee4..f057b53 100644 > --- a/include/uapi/xen/evtchn.h > +++ b/include/uapi/xen/evtchn.h > @@ -85,4 +85,19 @@ struct ioctl_evtchn_notify { > #define IOCTL_EVTCHN_RESET \ > _IOC(_IOC_NONE, 'E', 5, 0) > > +/* > + * Restrict this file descriptor so that it can only be used to bind > + * new interdomain events from one domain. > + * > + * Once a file descriptor has been restricted it cannot be > + * de-restricted, and must be closed and re-opened. Event channels > + * which were bound before restricting remain bound afterwards, and > + * can be notified as usual. > + */ > +#define IOCTL_EVTCHN_RESTRICT_DOMID \ > + _IOC(_IOC_NONE, 'E', 100, sizeof(struct ioctl_evtchn_restrict_domid)) Is there a reason why you picked 100 and not 6? -boris
On 11/07/16 16:31, Boris Ostrovsky wrote: > On 07/11/2016 10:57 AM, David Vrabel wrote: >> diff --git a/include/uapi/xen/evtchn.h b/include/uapi/xen/evtchn.h >> index 14e833ee4..f057b53 100644 >> --- a/include/uapi/xen/evtchn.h >> +++ b/include/uapi/xen/evtchn.h >> @@ -85,4 +85,19 @@ struct ioctl_evtchn_notify { >> #define IOCTL_EVTCHN_RESET \ >> _IOC(_IOC_NONE, 'E', 5, 0) >> >> +/* >> + * Restrict this file descriptor so that it can only be used to bind >> + * new interdomain events from one domain. >> + * >> + * Once a file descriptor has been restricted it cannot be >> + * de-restricted, and must be closed and re-opened. Event channels >> + * which were bound before restricting remain bound afterwards, and >> + * can be notified as usual. >> + */ >> +#define IOCTL_EVTCHN_RESTRICT_DOMID \ >> + _IOC(_IOC_NONE, 'E', 100, sizeof(struct ioctl_evtchn_restrict_domid)) > > Is there a reason why you picked 100 and not 6? Because we've had this patch for years in xenserver like this and I didn't see any need to change the ABI. But if it's preferred I can make this 6 (and manage the transition internally). David
On 11/07/16 17:15, David Vrabel wrote: > On 11/07/16 16:31, Boris Ostrovsky wrote: >> On 07/11/2016 10:57 AM, David Vrabel wrote: >>> diff --git a/include/uapi/xen/evtchn.h b/include/uapi/xen/evtchn.h >>> index 14e833ee4..f057b53 100644 >>> --- a/include/uapi/xen/evtchn.h >>> +++ b/include/uapi/xen/evtchn.h >>> @@ -85,4 +85,19 @@ struct ioctl_evtchn_notify { >>> #define IOCTL_EVTCHN_RESET \ >>> _IOC(_IOC_NONE, 'E', 5, 0) >>> >>> +/* >>> + * Restrict this file descriptor so that it can only be used to bind >>> + * new interdomain events from one domain. >>> + * >>> + * Once a file descriptor has been restricted it cannot be >>> + * de-restricted, and must be closed and re-opened. Event channels >>> + * which were bound before restricting remain bound afterwards, and >>> + * can be notified as usual. >>> + */ >>> +#define IOCTL_EVTCHN_RESTRICT_DOMID \ >>> + _IOC(_IOC_NONE, 'E', 100, sizeof(struct ioctl_evtchn_restrict_domid)) >> Is there a reason why you picked 100 and not 6? > Because we've had this patch for years in xenserver like this and I > didn't see any need to change the ABI. But if it's preferred I can make > this 6 (and manage the transition internally). This should become 6, and we manage the transition. It is not like its hard to manage. ~Andrew
On 11/07/16 17:33, Andrew Cooper wrote: > On 11/07/16 17:15, David Vrabel wrote: >> On 11/07/16 16:31, Boris Ostrovsky wrote: >>> On 07/11/2016 10:57 AM, David Vrabel wrote: >>>> diff --git a/include/uapi/xen/evtchn.h b/include/uapi/xen/evtchn.h >>>> index 14e833ee4..f057b53 100644 >>>> --- a/include/uapi/xen/evtchn.h >>>> +++ b/include/uapi/xen/evtchn.h >>>> @@ -85,4 +85,19 @@ struct ioctl_evtchn_notify { >>>> #define IOCTL_EVTCHN_RESET \ >>>> _IOC(_IOC_NONE, 'E', 5, 0) >>>> >>>> +/* >>>> + * Restrict this file descriptor so that it can only be used to bind >>>> + * new interdomain events from one domain. >>>> + * >>>> + * Once a file descriptor has been restricted it cannot be >>>> + * de-restricted, and must be closed and re-opened. Event channels >>>> + * which were bound before restricting remain bound afterwards, and >>>> + * can be notified as usual. >>>> + */ >>>> +#define IOCTL_EVTCHN_RESTRICT_DOMID \ >>>> + _IOC(_IOC_NONE, 'E', 100, sizeof(struct ioctl_evtchn_restrict_domid)) >>> Is there a reason why you picked 100 and not 6? >> Because we've had this patch for years in xenserver like this and I >> didn't see any need to change the ABI. But if it's preferred I can make >> this 6 (and manage the transition internally). > > This should become 6, and we manage the transition. It is not like its > hard to manage. Ok. David
On 07/11/2016 12:44 PM, David Vrabel wrote: > On 11/07/16 17:33, Andrew Cooper wrote: >> On 11/07/16 17:15, David Vrabel wrote: >>> On 11/07/16 16:31, Boris Ostrovsky wrote: >>>> On 07/11/2016 10:57 AM, David Vrabel wrote: >>>>> diff --git a/include/uapi/xen/evtchn.h b/include/uapi/xen/evtchn.h >>>>> index 14e833ee4..f057b53 100644 >>>>> --- a/include/uapi/xen/evtchn.h >>>>> +++ b/include/uapi/xen/evtchn.h >>>>> @@ -85,4 +85,19 @@ struct ioctl_evtchn_notify { >>>>> #define IOCTL_EVTCHN_RESET \ >>>>> _IOC(_IOC_NONE, 'E', 5, 0) >>>>> >>>>> +/* >>>>> + * Restrict this file descriptor so that it can only be used to bind >>>>> + * new interdomain events from one domain. >>>>> + * >>>>> + * Once a file descriptor has been restricted it cannot be >>>>> + * de-restricted, and must be closed and re-opened. Event channels >>>>> + * which were bound before restricting remain bound afterwards, and >>>>> + * can be notified as usual. >>>>> + */ >>>>> +#define IOCTL_EVTCHN_RESTRICT_DOMID \ >>>>> + _IOC(_IOC_NONE, 'E', 100, sizeof(struct ioctl_evtchn_restrict_domid)) >>>> Is there a reason why you picked 100 and not 6? >>> Because we've had this patch for years in xenserver like this and I >>> didn't see any need to change the ABI. But if it's preferred I can make >>> this 6 (and manage the transition internally). >> This should become 6, and we manage the transition. It is not like its >> hard to manage. > Ok. With that Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>>> On 11.07.16 at 16:57, <david.vrabel@citrix.com> wrote: > @@ -553,6 +570,27 @@ static long evtchn_ioctl(struct file *file, > break; > } > > + case IOCTL_EVTCHN_RESTRICT_DOMID: { > + struct ioctl_evtchn_restrict_domid ierd; > + > + rc = -EACCES; > + if (u->restrict_domid != UNRESTRICTED_DOMID) > + break; > + > + rc = -EFAULT; > + if (copy_from_user(&ierd, uarg, sizeof(ierd))) > + break; > + > + rc = -EINVAL; > + if (ierd.domid == 0 || ierd.domid >= DOMID_FIRST_RESERVED) > + break; Any reason you special case Dom0 here, but not the conceptually more general hardware and/or control domain? Jan
On 01/08/16 12:15, Jan Beulich wrote: >>>> On 11.07.16 at 16:57, <david.vrabel@citrix.com> wrote: >> @@ -553,6 +570,27 @@ static long evtchn_ioctl(struct file *file, >> break; >> } >> >> + case IOCTL_EVTCHN_RESTRICT_DOMID: { >> + struct ioctl_evtchn_restrict_domid ierd; >> + >> + rc = -EACCES; >> + if (u->restrict_domid != UNRESTRICTED_DOMID) >> + break; >> + >> + rc = -EFAULT; >> + if (copy_from_user(&ierd, uarg, sizeof(ierd))) >> + break; >> + >> + rc = -EINVAL; >> + if (ierd.domid == 0 || ierd.domid >= DOMID_FIRST_RESERVED) >> + break; > > Any reason you special case Dom0 here, but not the conceptually > more general hardware and/or control domain? I don't know why that check is there. I think it can be removed. David
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c index f4edd6d..7efd1cb 100644 --- a/drivers/xen/evtchn.c +++ b/drivers/xen/evtchn.c @@ -73,8 +73,12 @@ struct per_user_data { wait_queue_head_t evtchn_wait; struct fasync_struct *evtchn_async_queue; const char *name; + + domid_t restrict_domid; }; +#define UNRESTRICTED_DOMID ((domid_t)-1) + struct user_evtchn { struct rb_node node; struct per_user_data *user; @@ -443,6 +447,10 @@ static long evtchn_ioctl(struct file *file, struct ioctl_evtchn_bind_virq bind; struct evtchn_bind_virq bind_virq; + rc = -EACCES; + if (u->restrict_domid != UNRESTRICTED_DOMID) + break; + rc = -EFAULT; if (copy_from_user(&bind, uarg, sizeof(bind))) break; @@ -468,6 +476,11 @@ static long evtchn_ioctl(struct file *file, if (copy_from_user(&bind, uarg, sizeof(bind))) break; + rc = -EACCES; + if (u->restrict_domid != UNRESTRICTED_DOMID && + u->restrict_domid != bind.remote_domain) + break; + bind_interdomain.remote_dom = bind.remote_domain; bind_interdomain.remote_port = bind.remote_port; rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain, @@ -485,6 +498,10 @@ static long evtchn_ioctl(struct file *file, struct ioctl_evtchn_bind_unbound_port bind; struct evtchn_alloc_unbound alloc_unbound; + rc = -EACCES; + if (u->restrict_domid != UNRESTRICTED_DOMID) + break; + rc = -EFAULT; if (copy_from_user(&bind, uarg, sizeof(bind))) break; @@ -553,6 +570,27 @@ static long evtchn_ioctl(struct file *file, break; } + case IOCTL_EVTCHN_RESTRICT_DOMID: { + struct ioctl_evtchn_restrict_domid ierd; + + rc = -EACCES; + if (u->restrict_domid != UNRESTRICTED_DOMID) + break; + + rc = -EFAULT; + if (copy_from_user(&ierd, uarg, sizeof(ierd))) + break; + + rc = -EINVAL; + if (ierd.domid == 0 || ierd.domid >= DOMID_FIRST_RESERVED) + break; + + u->restrict_domid = ierd.domid; + rc = 0; + + break; + } + default: rc = -ENOSYS; break; @@ -601,6 +639,8 @@ static int evtchn_open(struct inode *inode, struct file *filp) mutex_init(&u->ring_cons_mutex); spin_lock_init(&u->ring_prod_lock); + u->restrict_domid = UNRESTRICTED_DOMID; + filp->private_data = u; return nonseekable_open(inode, filp); diff --git a/include/uapi/xen/evtchn.h b/include/uapi/xen/evtchn.h index 14e833ee4..f057b53 100644 --- a/include/uapi/xen/evtchn.h +++ b/include/uapi/xen/evtchn.h @@ -85,4 +85,19 @@ struct ioctl_evtchn_notify { #define IOCTL_EVTCHN_RESET \ _IOC(_IOC_NONE, 'E', 5, 0) +/* + * Restrict this file descriptor so that it can only be used to bind + * new interdomain events from one domain. + * + * Once a file descriptor has been restricted it cannot be + * de-restricted, and must be closed and re-opened. Event channels + * which were bound before restricting remain bound afterwards, and + * can be notified as usual. + */ +#define IOCTL_EVTCHN_RESTRICT_DOMID \ + _IOC(_IOC_NONE, 'E', 100, sizeof(struct ioctl_evtchn_restrict_domid)) +struct ioctl_evtchn_restrict_domid { + domid_t domid; +}; + #endif /* __LINUX_PUBLIC_EVTCHN_H__ */
IOCTL_EVTCHN_RESTRICT limits the file descriptor to being able to bind to interdomain event channels from a specific domain. Event channels that are already bound continue to work for sending and receiving notifications. This is useful as part of deprivileging a user space PV backend or device model (QEMU). e.g., Once the device model as bound to the ioreq server event channels it can restrict the file handle so an exploited DM cannot use it to create or bind to arbitrary event channels. Signed-off-by: David Vrabel <david.vrabel@citrix.com> --- drivers/xen/evtchn.c | 40 ++++++++++++++++++++++++++++++++++++++++ include/uapi/xen/evtchn.h | 15 +++++++++++++++ 2 files changed, 55 insertions(+)