| Message ID | 20231020155819.24000-5-maxime.coquelin@redhat.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Delegated to: | Paul Moore |
| Headers | show |
| Series | vduse: add support for networking devices | expand |
On 10/20/2023 8:58 AM, Maxime Coquelin wrote: > This patch introduces LSM hooks for devices creation, > destruction and opening operations, checking the > application is allowed to perform these operations for > the Virtio device type. Why do you think that there needs to be a special LSM check for virtio devices? What can't existing device attributes be used? > > Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> > --- > drivers/vdpa/vdpa_user/vduse_dev.c | 12 +++++++ > include/linux/lsm_hook_defs.h | 4 +++ > include/linux/security.h | 15 ++++++++ > security/security.c | 42 ++++++++++++++++++++++ > security/selinux/hooks.c | 55 +++++++++++++++++++++++++++++ > security/selinux/include/classmap.h | 2 ++ > 6 files changed, 130 insertions(+) > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c > index 0243dee9cf0e..ca64eac11ddb 100644 > --- a/drivers/vdpa/vdpa_user/vduse_dev.c > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c > @@ -8,6 +8,7 @@ > * > */ > > +#include "linux/security.h" > #include <linux/init.h> > #include <linux/module.h> > #include <linux/cdev.h> > @@ -1443,6 +1444,10 @@ static int vduse_dev_open(struct inode *inode, struct file *file) > if (dev->connected) > goto unlock; > > + ret = -EPERM; > + if (security_vduse_dev_open(dev->device_id)) > + goto unlock; > + > ret = 0; > dev->connected = true; > file->private_data = dev; > @@ -1655,6 +1660,9 @@ static int vduse_destroy_dev(char *name) > if (!dev) > return -EINVAL; > > + if (security_vduse_dev_destroy(dev->device_id)) > + return -EPERM; > + > mutex_lock(&dev->lock); > if (dev->vdev || dev->connected) { > mutex_unlock(&dev->lock); > @@ -1819,6 +1827,10 @@ static int vduse_create_dev(struct vduse_dev_config *config, > int ret; > struct vduse_dev *dev; > > + ret = -EPERM; > + if (security_vduse_dev_create(config->device_id)) > + goto err; > + > ret = -EEXIST; > if (vduse_find_dev(config->name)) > goto err; > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index ac962c4cb44b..0b3999ab3264 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -419,3 +419,7 @@ LSM_HOOK(int, 0, uring_override_creds, const struct cred *new) > LSM_HOOK(int, 0, uring_sqpoll, void) > LSM_HOOK(int, 0, uring_cmd, struct io_uring_cmd *ioucmd) > #endif /* CONFIG_IO_URING */ > + > +LSM_HOOK(int, 0, vduse_dev_create, u32 device_id) > +LSM_HOOK(int, 0, vduse_dev_destroy, u32 device_id) > +LSM_HOOK(int, 0, vduse_dev_open, u32 device_id) > diff --git a/include/linux/security.h b/include/linux/security.h > index 5f16eecde00b..a650c500f841 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -484,6 +484,9 @@ int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen); > int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen); > int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen); > int security_locked_down(enum lockdown_reason what); > +int security_vduse_dev_create(u32 device_id); > +int security_vduse_dev_destroy(u32 device_id); > +int security_vduse_dev_open(u32 device_id); > #else /* CONFIG_SECURITY */ > > static inline int call_blocking_lsm_notifier(enum lsm_event event, void *data) > @@ -1395,6 +1398,18 @@ static inline int security_locked_down(enum lockdown_reason what) > { > return 0; > } > +static inline int security_vduse_dev_create(u32 device_id) > +{ > + return 0; > +} > +static inline int security_vduse_dev_destroy(u32 device_id) > +{ > + return 0; > +} > +static inline int security_vduse_dev_open(u32 device_id) > +{ > + return 0; > +} > #endif /* CONFIG_SECURITY */ > > #if defined(CONFIG_SECURITY) && defined(CONFIG_WATCH_QUEUE) > diff --git a/security/security.c b/security/security.c > index 23b129d482a7..8d7d4d2eca0b 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -5337,3 +5337,45 @@ int security_uring_cmd(struct io_uring_cmd *ioucmd) > return call_int_hook(uring_cmd, 0, ioucmd); > } > #endif /* CONFIG_IO_URING */ > + > +/** > + * security_vduse_dev_create() - Check if a VDUSE device type creation is allowed > + * @device_id: the Virtio device ID > + * > + * Check whether the Virtio device creation is allowed > + * > + * Return: Returns 0 if permission is granted. > + */ > +int security_vduse_dev_create(u32 device_id) > +{ > + return call_int_hook(vduse_dev_create, 0, device_id); > +} > +EXPORT_SYMBOL(security_vduse_dev_create); > + > +/** > + * security_vduse_dev_destroy() - Check if a VDUSE device type destruction is allowed > + * @device_id: the Virtio device ID > + * > + * Check whether the Virtio device destruction is allowed > + * > + * Return: Returns 0 if permission is granted. > + */ > +int security_vduse_dev_destroy(u32 device_id) > +{ > + return call_int_hook(vduse_dev_destroy, 0, device_id); > +} > +EXPORT_SYMBOL(security_vduse_dev_destroy); > + > +/** > + * security_vduse_dev_open() - Check if a VDUSE device type opening is allowed > + * @device_id: the Virtio device ID > + * > + * Check whether the Virtio device opening is allowed > + * > + * Return: Returns 0 if permission is granted. > + */ > +int security_vduse_dev_open(u32 device_id) > +{ > + return call_int_hook(vduse_dev_open, 0, device_id); > +} > +EXPORT_SYMBOL(security_vduse_dev_open); > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index 2aa0e219d721..65d9262a37f7 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -21,6 +21,7 @@ > * Copyright (C) 2016 Mellanox Technologies > */ > > +#include "av_permissions.h" > #include <linux/init.h> > #include <linux/kd.h> > #include <linux/kernel.h> > @@ -92,6 +93,7 @@ > #include <linux/fsnotify.h> > #include <linux/fanotify.h> > #include <linux/io_uring.h> > +#include <uapi/linux/virtio_ids.h> > > #include "avc.h" > #include "objsec.h" > @@ -6950,6 +6952,56 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) > } > #endif /* CONFIG_IO_URING */ > > +static int vduse_check_device_type(u32 sid, u32 device_id) > +{ > + u32 requested; > + > + if (device_id == VIRTIO_ID_NET) > + requested = VDUSE__NET; > + else if (device_id == VIRTIO_ID_BLOCK) > + requested = VDUSE__BLOCK; > + else > + return -EINVAL; > + > + return avc_has_perm(sid, sid, SECCLASS_VDUSE, requested, NULL); > +} > + > +static int selinux_vduse_dev_create(u32 device_id) > +{ > + u32 sid = current_sid(); > + int ret; > + > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVCREATE, NULL); > + if (ret) > + return ret; > + > + return vduse_check_device_type(sid, device_id); > +} > + > +static int selinux_vduse_dev_destroy(u32 device_id) > +{ > + u32 sid = current_sid(); > + int ret; > + > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVDESTROY, NULL); > + if (ret) > + return ret; > + > + return vduse_check_device_type(sid, device_id); > +} > + > +static int selinux_vduse_dev_open(u32 device_id) > +{ > + u32 sid = current_sid(); > + int ret; > + > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVOPEN, NULL); > + if (ret) > + return ret; > + > + return vduse_check_device_type(sid, device_id); > +} > + > /* > * IMPORTANT NOTE: When adding new hooks, please be careful to keep this order: > * 1. any hooks that don't belong to (2.) or (3.) below, > @@ -7243,6 +7295,9 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { > #ifdef CONFIG_PERF_EVENTS > LSM_HOOK_INIT(perf_event_alloc, selinux_perf_event_alloc), > #endif > + LSM_HOOK_INIT(vduse_dev_create, selinux_vduse_dev_create), > + LSM_HOOK_INIT(vduse_dev_destroy, selinux_vduse_dev_destroy), > + LSM_HOOK_INIT(vduse_dev_open, selinux_vduse_dev_open), > }; > > static __init int selinux_init(void) > diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h > index a3c380775d41..d3dc37fb03d4 100644 > --- a/security/selinux/include/classmap.h > +++ b/security/selinux/include/classmap.h > @@ -256,6 +256,8 @@ const struct security_class_mapping secclass_map[] = { > { "override_creds", "sqpoll", "cmd", NULL } }, > { "user_namespace", > { "create", NULL } }, > + { "vduse", > + { "devcreate", "devdestroy", "devopen", "net", "block", NULL} }, > { NULL } > }; >
On Fri, Oct 20, 2023 at 11:58 PM Maxime Coquelin <maxime.coquelin@redhat.com> wrote: > > This patch introduces LSM hooks for devices creation, > destruction and opening operations, checking the > application is allowed to perform these operations for > the Virtio device type. > > Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> > --- Hi Maxime: I think we need to document the reason why we need those hooks now. Thanks
On 10/21/23 00:20, Casey Schaufler wrote: > On 10/20/2023 8:58 AM, Maxime Coquelin wrote: >> This patch introduces LSM hooks for devices creation, >> destruction and opening operations, checking the >> application is allowed to perform these operations for >> the Virtio device type. > > Why do you think that there needs to be a special LSM check for virtio > devices? What can't existing device attributes be used? Michael asked for a way for SELinux to allow/prevent the creation of some types of devices [0]. A device is created using ioctl() on VDUSE control chardev. Its type is specified via a field in the structure passed in argument. I didn't see other way than adding dedicated LSM hooks to achieve this, but it is possible that their is a better way to do it? Thanks, Maxime [0]: https://lore.kernel.org/all/20230829130430-mutt-send-email-mst@kernel.org/
On 10/23/2023 12:28 AM, Maxime Coquelin wrote: > > > On 10/21/23 00:20, Casey Schaufler wrote: >> On 10/20/2023 8:58 AM, Maxime Coquelin wrote: >>> This patch introduces LSM hooks for devices creation, >>> destruction and opening operations, checking the >>> application is allowed to perform these operations for >>> the Virtio device type. >> >> Why do you think that there needs to be a special LSM check for virtio >> devices? What can't existing device attributes be used? > > Michael asked for a way for SELinux to allow/prevent the creation of > some types of devices [0]. > > A device is created using ioctl() on VDUSE control chardev. Its type is > specified via a field in the structure passed in argument. > > I didn't see other way than adding dedicated LSM hooks to achieve this, > but it is possible that their is a better way to do it? At the very least the hook should be made more general, and I'd have to see a proposal before commenting on that. security_dev_destroy(dev) might be a better approach. If there's reason to control destruction of vduse devices it's reasonable to assume that there are other devices with the same or similar properties. Since SELinux is your target use case, can you explain why you can't create SELinux policy to enforce the restrictions you're after? I believe (but can be proven wrong, of course) that SELinux has mechanism for dealing with controls on ioctls. > > Thanks, > Maxime > > [0]: > https://lore.kernel.org/all/20230829130430-mutt-send-email-mst@kernel.org/ >
On 10/23/23 17:13, Casey Schaufler wrote: > On 10/23/2023 12:28 AM, Maxime Coquelin wrote: >> >> >> On 10/21/23 00:20, Casey Schaufler wrote: >>> On 10/20/2023 8:58 AM, Maxime Coquelin wrote: >>>> This patch introduces LSM hooks for devices creation, >>>> destruction and opening operations, checking the >>>> application is allowed to perform these operations for >>>> the Virtio device type. >>> >>> Why do you think that there needs to be a special LSM check for virtio >>> devices? What can't existing device attributes be used? >> >> Michael asked for a way for SELinux to allow/prevent the creation of >> some types of devices [0]. >> >> A device is created using ioctl() on VDUSE control chardev. Its type is >> specified via a field in the structure passed in argument. >> >> I didn't see other way than adding dedicated LSM hooks to achieve this, >> but it is possible that their is a better way to do it? > > At the very least the hook should be made more general, and I'd have to > see a proposal before commenting on that. security_dev_destroy(dev) might > be a better approach. If there's reason to control destruction of vduse > devices it's reasonable to assume that there are other devices with the > same or similar properties. VDUSE is different from other devices as the device is actually implemented by the user-space application, so this is very specific in my opinion. > > Since SELinux is your target use case, can you explain why you can't > create SELinux policy to enforce the restrictions you're after? I believe > (but can be proven wrong, of course) that SELinux has mechanism for dealing > with controls on ioctls. > I am not aware of such mechanism to deal with ioctl(), if you have a pointer that would be welcome. Thanks, Maxime > >> >> Thanks, >> Maxime >> >> [0]: >> https://lore.kernel.org/all/20230829130430-mutt-send-email-mst@kernel.org/ >> >
On 10/24/2023 2:49 AM, Maxime Coquelin wrote: > > > On 10/23/23 17:13, Casey Schaufler wrote: >> On 10/23/2023 12:28 AM, Maxime Coquelin wrote: >>> >>> >>> On 10/21/23 00:20, Casey Schaufler wrote: >>>> On 10/20/2023 8:58 AM, Maxime Coquelin wrote: >>>>> This patch introduces LSM hooks for devices creation, >>>>> destruction and opening operations, checking the >>>>> application is allowed to perform these operations for >>>>> the Virtio device type. >>>> >>>> Why do you think that there needs to be a special LSM check for virtio >>>> devices? What can't existing device attributes be used? >>> >>> Michael asked for a way for SELinux to allow/prevent the creation of >>> some types of devices [0]. >>> >>> A device is created using ioctl() on VDUSE control chardev. Its type is >>> specified via a field in the structure passed in argument. >>> >>> I didn't see other way than adding dedicated LSM hooks to achieve this, >>> but it is possible that their is a better way to do it? >> >> At the very least the hook should be made more general, and I'd have to >> see a proposal before commenting on that. security_dev_destroy(dev) >> might >> be a better approach. If there's reason to control destruction of vduse >> devices it's reasonable to assume that there are other devices with the >> same or similar properties. > > VDUSE is different from other devices as the device is actually > implemented by the user-space application, so this is very specific in > my opinion. This is hardly unique. If you're implementing the device in user-space you may well be able to implement the desired controls there. > >> >> Since SELinux is your target use case, can you explain why you can't >> create SELinux policy to enforce the restrictions you're after? I >> believe >> (but can be proven wrong, of course) that SELinux has mechanism for >> dealing >> with controls on ioctls. >> > > I am not aware of such mechanism to deal with ioctl(), if you have a > pointer that would be welcome. security/selinux/hooks.c > > Thanks, > Maxime > >> >>> >>> Thanks, >>> Maxime >>> >>> [0]: >>> https://lore.kernel.org/all/20230829130430-mutt-send-email-mst@kernel.org/ >>> >>> >> >
On 10/24/23 17:30, Casey Schaufler wrote: > On 10/24/2023 2:49 AM, Maxime Coquelin wrote: >> >> >> On 10/23/23 17:13, Casey Schaufler wrote: >>> On 10/23/2023 12:28 AM, Maxime Coquelin wrote: >>>> >>>> >>>> On 10/21/23 00:20, Casey Schaufler wrote: >>>>> On 10/20/2023 8:58 AM, Maxime Coquelin wrote: >>>>>> This patch introduces LSM hooks for devices creation, >>>>>> destruction and opening operations, checking the >>>>>> application is allowed to perform these operations for >>>>>> the Virtio device type. >>>>> >>>>> Why do you think that there needs to be a special LSM check for virtio >>>>> devices? What can't existing device attributes be used? >>>> >>>> Michael asked for a way for SELinux to allow/prevent the creation of >>>> some types of devices [0]. >>>> >>>> A device is created using ioctl() on VDUSE control chardev. Its type is >>>> specified via a field in the structure passed in argument. >>>> >>>> I didn't see other way than adding dedicated LSM hooks to achieve this, >>>> but it is possible that their is a better way to do it? >>> >>> At the very least the hook should be made more general, and I'd have to >>> see a proposal before commenting on that. security_dev_destroy(dev) >>> might >>> be a better approach. If there's reason to control destruction of vduse >>> devices it's reasonable to assume that there are other devices with the >>> same or similar properties. >> >> VDUSE is different from other devices as the device is actually >> implemented by the user-space application, so this is very specific in >> my opinion. > > This is hardly unique. If you're implementing the device > in user-space you may well be able to implement the desired > controls there. > >> >>> >>> Since SELinux is your target use case, can you explain why you can't >>> create SELinux policy to enforce the restrictions you're after? I >>> believe >>> (but can be proven wrong, of course) that SELinux has mechanism for >>> dealing >>> with controls on ioctls. >>> >> >> I am not aware of such mechanism to deal with ioctl(), if you have a >> pointer that would be welcome. > > security/selinux/hooks.c We might be able to extend selinux_file_ioctl(), but that will only covers the ioctl for the control file, this patch also adds hook for the device file opening that would need dedicated hook as the device type information is stored in the device's private data. Michael, before going further, I would be interested in your feedback. Was this patch what you had in mind when requesting for a way to allow/deny devices types for a given application? Regards, Maxime > >> >> Thanks, >> Maxime >> >>> >>>> >>>> Thanks, >>>> Maxime >>>> >>>> [0]: >>>> https://lore.kernel.org/all/20230829130430-mutt-send-email-mst@kernel.org/ >>>> >>>> >>> >> >
On Thu, Nov 02, 2023 at 06:56:59PM +0100, Maxime Coquelin wrote: > > > On 10/24/23 17:30, Casey Schaufler wrote: > > On 10/24/2023 2:49 AM, Maxime Coquelin wrote: > > > > > > > > > On 10/23/23 17:13, Casey Schaufler wrote: > > > > On 10/23/2023 12:28 AM, Maxime Coquelin wrote: > > > > > > > > > > > > > > > On 10/21/23 00:20, Casey Schaufler wrote: > > > > > > On 10/20/2023 8:58 AM, Maxime Coquelin wrote: > > > > > > > This patch introduces LSM hooks for devices creation, > > > > > > > destruction and opening operations, checking the > > > > > > > application is allowed to perform these operations for > > > > > > > the Virtio device type. > > > > > > > > > > > > Why do you think that there needs to be a special LSM check for virtio > > > > > > devices? What can't existing device attributes be used? > > > > > > > > > > Michael asked for a way for SELinux to allow/prevent the creation of > > > > > some types of devices [0]. > > > > > > > > > > A device is created using ioctl() on VDUSE control chardev. Its type is > > > > > specified via a field in the structure passed in argument. > > > > > > > > > > I didn't see other way than adding dedicated LSM hooks to achieve this, > > > > > but it is possible that their is a better way to do it? > > > > > > > > At the very least the hook should be made more general, and I'd have to > > > > see a proposal before commenting on that. security_dev_destroy(dev) > > > > might > > > > be a better approach. If there's reason to control destruction of vduse > > > > devices it's reasonable to assume that there are other devices with the > > > > same or similar properties. > > > > > > VDUSE is different from other devices as the device is actually > > > implemented by the user-space application, so this is very specific in > > > my opinion. > > > > This is hardly unique. If you're implementing the device > > in user-space you may well be able to implement the desired > > controls there. > > > > > > > > > > > > > Since SELinux is your target use case, can you explain why you can't > > > > create SELinux policy to enforce the restrictions you're after? I > > > > believe > > > > (but can be proven wrong, of course) that SELinux has mechanism for > > > > dealing > > > > with controls on ioctls. > > > > > > > > > > I am not aware of such mechanism to deal with ioctl(), if you have a > > > pointer that would be welcome. > > > > security/selinux/hooks.c > > We might be able to extend selinux_file_ioctl(), but that will only > covers the ioctl for the control file, this patch also adds hook for the > device file opening that would need dedicated hook as the device type > information is stored in the device's private data. > > Michael, before going further, I would be interested in your feedback. > Was this patch what you had in mind when requesting for a way to > allow/deny devices types for a given application? > > Regards, > Maxime Yes, this is more or less what I had in mind. > > > > > > > > Thanks, > > > Maxime > > > > > > > > > > > > > > > > > Thanks, > > > > > Maxime > > > > > > > > > > [0]: > > > > > https://lore.kernel.org/all/20230829130430-mutt-send-email-mst@kernel.org/ > > > > > > > > > > > > > > > > > > >
On 11/2/23 19:59, Michael S. Tsirkin wrote: > On Thu, Nov 02, 2023 at 06:56:59PM +0100, Maxime Coquelin wrote: >> >> >> On 10/24/23 17:30, Casey Schaufler wrote: >>> On 10/24/2023 2:49 AM, Maxime Coquelin wrote: >>>> >>>> >>>> On 10/23/23 17:13, Casey Schaufler wrote: >>>>> On 10/23/2023 12:28 AM, Maxime Coquelin wrote: >>>>>> >>>>>> >>>>>> On 10/21/23 00:20, Casey Schaufler wrote: >>>>>>> On 10/20/2023 8:58 AM, Maxime Coquelin wrote: >>>>>>>> This patch introduces LSM hooks for devices creation, >>>>>>>> destruction and opening operations, checking the >>>>>>>> application is allowed to perform these operations for >>>>>>>> the Virtio device type. >>>>>>> >>>>>>> Why do you think that there needs to be a special LSM check for virtio >>>>>>> devices? What can't existing device attributes be used? >>>>>> >>>>>> Michael asked for a way for SELinux to allow/prevent the creation of >>>>>> some types of devices [0]. >>>>>> >>>>>> A device is created using ioctl() on VDUSE control chardev. Its type is >>>>>> specified via a field in the structure passed in argument. >>>>>> >>>>>> I didn't see other way than adding dedicated LSM hooks to achieve this, >>>>>> but it is possible that their is a better way to do it? >>>>> >>>>> At the very least the hook should be made more general, and I'd have to >>>>> see a proposal before commenting on that. security_dev_destroy(dev) >>>>> might >>>>> be a better approach. If there's reason to control destruction of vduse >>>>> devices it's reasonable to assume that there are other devices with the >>>>> same or similar properties. >>>> >>>> VDUSE is different from other devices as the device is actually >>>> implemented by the user-space application, so this is very specific in >>>> my opinion. >>> >>> This is hardly unique. If you're implementing the device >>> in user-space you may well be able to implement the desired >>> controls there. >>> >>>> >>>>> >>>>> Since SELinux is your target use case, can you explain why you can't >>>>> create SELinux policy to enforce the restrictions you're after? I >>>>> believe >>>>> (but can be proven wrong, of course) that SELinux has mechanism for >>>>> dealing >>>>> with controls on ioctls. >>>>> >>>> >>>> I am not aware of such mechanism to deal with ioctl(), if you have a >>>> pointer that would be welcome. >>> >>> security/selinux/hooks.c >> >> We might be able to extend selinux_file_ioctl(), but that will only >> covers the ioctl for the control file, this patch also adds hook for the >> device file opening that would need dedicated hook as the device type >> information is stored in the device's private data. >> >> Michael, before going further, I would be interested in your feedback. >> Was this patch what you had in mind when requesting for a way to >> allow/deny devices types for a given application? >> >> Regards, >> Maxime > > > Yes, this is more or less what I had in mind. Great. Do you think we need to cover both ioctl() on the control file and open() on the device file, or only ioctl() is enough? If the former, we will need VDUSE-specific hooks. I may be able to improve my patch to have a single hook instead of 3 by passing the type of operation as an extra argument (create/destroy/open). If the latter, we may be able to extend the generic ioctl hook. Personally, I think it would make sense to also ensure a given application can only open existing VDUSE devices it supports. For example, openvswitch should only be allowed to open networking VDUSE devices. Thanks, Maxime > >>> >>>> >>>> Thanks, >>>> Maxime >>>> >>>>> >>>>>> >>>>>> Thanks, >>>>>> Maxime >>>>>> >>>>>> [0]: >>>>>> https://lore.kernel.org/all/20230829130430-mutt-send-email-mst@kernel.org/ >>>>>> >>>>>> >>>>> >>>> >>> >
On Fri, Nov 03, 2023 at 08:55:19AM +0100, Maxime Coquelin wrote: > > > On 11/2/23 19:59, Michael S. Tsirkin wrote: > > On Thu, Nov 02, 2023 at 06:56:59PM +0100, Maxime Coquelin wrote: > > > > > > > > > On 10/24/23 17:30, Casey Schaufler wrote: > > > > On 10/24/2023 2:49 AM, Maxime Coquelin wrote: > > > > > > > > > > > > > > > On 10/23/23 17:13, Casey Schaufler wrote: > > > > > > On 10/23/2023 12:28 AM, Maxime Coquelin wrote: > > > > > > > > > > > > > > > > > > > > > On 10/21/23 00:20, Casey Schaufler wrote: > > > > > > > > On 10/20/2023 8:58 AM, Maxime Coquelin wrote: > > > > > > > > > This patch introduces LSM hooks for devices creation, > > > > > > > > > destruction and opening operations, checking the > > > > > > > > > application is allowed to perform these operations for > > > > > > > > > the Virtio device type. > > > > > > > > > > > > > > > > Why do you think that there needs to be a special LSM check for virtio > > > > > > > > devices? What can't existing device attributes be used? > > > > > > > > > > > > > > Michael asked for a way for SELinux to allow/prevent the creation of > > > > > > > some types of devices [0]. > > > > > > > > > > > > > > A device is created using ioctl() on VDUSE control chardev. Its type is > > > > > > > specified via a field in the structure passed in argument. > > > > > > > > > > > > > > I didn't see other way than adding dedicated LSM hooks to achieve this, > > > > > > > but it is possible that their is a better way to do it? > > > > > > > > > > > > At the very least the hook should be made more general, and I'd have to > > > > > > see a proposal before commenting on that. security_dev_destroy(dev) > > > > > > might > > > > > > be a better approach. If there's reason to control destruction of vduse > > > > > > devices it's reasonable to assume that there are other devices with the > > > > > > same or similar properties. > > > > > > > > > > VDUSE is different from other devices as the device is actually > > > > > implemented by the user-space application, so this is very specific in > > > > > my opinion. > > > > > > > > This is hardly unique. If you're implementing the device > > > > in user-space you may well be able to implement the desired > > > > controls there. > > > > > > > > > > > > > > > > > > > > > Since SELinux is your target use case, can you explain why you can't > > > > > > create SELinux policy to enforce the restrictions you're after? I > > > > > > believe > > > > > > (but can be proven wrong, of course) that SELinux has mechanism for > > > > > > dealing > > > > > > with controls on ioctls. > > > > > > > > > > > > > > > > I am not aware of such mechanism to deal with ioctl(), if you have a > > > > > pointer that would be welcome. > > > > > > > > security/selinux/hooks.c > > > > > > We might be able to extend selinux_file_ioctl(), but that will only > > > covers the ioctl for the control file, this patch also adds hook for the > > > device file opening that would need dedicated hook as the device type > > > information is stored in the device's private data. > > > > > > Michael, before going further, I would be interested in your feedback. > > > Was this patch what you had in mind when requesting for a way to > > > allow/deny devices types for a given application? > > > > > > Regards, > > > Maxime > > > > > > Yes, this is more or less what I had in mind. > > Great. > > Do you think we need to cover both ioctl() on the control file and > open() on the device file, or only ioctl() is enough? > > If the former, we will need VDUSE-specific hooks. I may be able to > improve my patch to have a single hook instead of 3 by passing the type > of operation as an extra argument (create/destroy/open). > > If the latter, we may be able to extend the generic ioctl hook. > > Personally, I think it would make sense to also ensure a given > application can only open existing VDUSE devices it supports. For > example, openvswitch should only be allowed to open networking VDUSE > devices. > > Thanks, > Maxime I agree here. I think an open hook is important. Make sure to document the need in the cover letter and commit log. > > > > > > > > > > > > > > > > Thanks, > > > > > Maxime > > > > > > > > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > Maxime > > > > > > > > > > > > > > [0]: > > > > > > > https://lore.kernel.org/all/20230829130430-mutt-send-email-mst@kernel.org/ > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
On Oct 20, 2023 "Michael S. Tsirkin" <mst@redhat.com> wrote: > > This patch introduces LSM hooks for devices creation, > destruction and opening operations, checking the > application is allowed to perform these operations for > the Virtio device type. > > Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> > --- > drivers/vdpa/vdpa_user/vduse_dev.c | 12 +++++++ > include/linux/lsm_hook_defs.h | 4 +++ > include/linux/security.h | 15 ++++++++ > security/security.c | 42 ++++++++++++++++++++++ > security/selinux/hooks.c | 55 +++++++++++++++++++++++++++++ > security/selinux/include/classmap.h | 2 ++ > 6 files changed, 130 insertions(+) My apologies for the late reply, I've been trying to work my way through the review backlog but it has been taking longer than expected; comments below ... > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index 2aa0e219d721..65d9262a37f7 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -21,6 +21,7 @@ > * Copyright (C) 2016 Mellanox Technologies > */ > > +#include "av_permissions.h" > #include <linux/init.h> > #include <linux/kd.h> > #include <linux/kernel.h> > @@ -92,6 +93,7 @@ > #include <linux/fsnotify.h> > #include <linux/fanotify.h> > #include <linux/io_uring.h> > +#include <uapi/linux/virtio_ids.h> > > #include "avc.h" > #include "objsec.h" > @@ -6950,6 +6952,56 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) > } > #endif /* CONFIG_IO_URING */ > > +static int vduse_check_device_type(u32 sid, u32 device_id) > +{ > + u32 requested; > + > + if (device_id == VIRTIO_ID_NET) > + requested = VDUSE__NET; > + else if (device_id == VIRTIO_ID_BLOCK) > + requested = VDUSE__BLOCK; > + else > + return -EINVAL; > + > + return avc_has_perm(sid, sid, SECCLASS_VDUSE, requested, NULL); > +} > + > +static int selinux_vduse_dev_create(u32 device_id) > +{ > + u32 sid = current_sid(); > + int ret; > + > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVCREATE, NULL); > + if (ret) > + return ret; > + > + return vduse_check_device_type(sid, device_id); > +} I see there has been some discussion about the need for a dedicated create hook as opposed to using the existing ioctl controls. I think one important point that has been missing from the discussion is the idea of labeling the newly created device. Unfortunately prior to a few minutes ago I hadn't ever looked at VDUSE so please correct me if I get some things wrong :) From what I can see userspace creates a new VDUSE device with ioctl(VDUSE_CREATE_DEV), which trigger the creation of a new /dev/vduse/XXX device which will be labeled according to the udev and SELinux configuration, likely with a generic udev label. My question is if we want to be able to uniquely label each VDUSE device based on the process that initiates the device creation with the call to ioctl()? If that is the case, we would need a create hook not only to control the creation of the device, but to record the triggering process' label in the new device; this label would then be used in subsequent VDUSE open and destroy operations. The normal device file I/O operations would still be subject to the standard SELinux file I/O permissions using the device file label assigned by systemd/udev when the device was created. > +static int selinux_vduse_dev_destroy(u32 device_id) > +{ > + u32 sid = current_sid(); > + int ret; > + > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVDESTROY, NULL); > + if (ret) > + return ret; > + > + return vduse_check_device_type(sid, device_id); > +} > + > +static int selinux_vduse_dev_open(u32 device_id) > +{ > + u32 sid = current_sid(); > + int ret; > + > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVOPEN, NULL); > + if (ret) > + return ret; > + > + return vduse_check_device_type(sid, device_id); > +} > + > /* > * IMPORTANT NOTE: When adding new hooks, please be careful to keep this order: > * 1. any hooks that don't belong to (2.) or (3.) below, > @@ -7243,6 +7295,9 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { > #ifdef CONFIG_PERF_EVENTS > LSM_HOOK_INIT(perf_event_alloc, selinux_perf_event_alloc), > #endif > + LSM_HOOK_INIT(vduse_dev_create, selinux_vduse_dev_create), > + LSM_HOOK_INIT(vduse_dev_destroy, selinux_vduse_dev_destroy), > + LSM_HOOK_INIT(vduse_dev_open, selinux_vduse_dev_open), > }; > > static __init int selinux_init(void) > diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h > index a3c380775d41..d3dc37fb03d4 100644 > --- a/security/selinux/include/classmap.h > +++ b/security/selinux/include/classmap.h > @@ -256,6 +256,8 @@ const struct security_class_mapping secclass_map[] = { > { "override_creds", "sqpoll", "cmd", NULL } }, > { "user_namespace", > { "create", NULL } }, > + { "vduse", > + { "devcreate", "devdestroy", "devopen", "net", "block", NULL} }, I think we can just call the permissions "create", "open", and "destroy" since the "dev" prefix is somewhat implied by this being a dedicated VDUSE object class. I don't see where you are using the "net" and "block" permissions above, is this a leftover from a prior draft of this patch or are you planning to do something with these permissions? > { NULL } > }; > > -- > 2.41.0 -- paul-moore.com
Hello Paul, On 11/8/23 03:31, Paul Moore wrote: > On Oct 20, 2023 "Michael S. Tsirkin" <mst@redhat.com> wrote: >> >> This patch introduces LSM hooks for devices creation, >> destruction and opening operations, checking the >> application is allowed to perform these operations for >> the Virtio device type. >> >> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> >> --- >> drivers/vdpa/vdpa_user/vduse_dev.c | 12 +++++++ >> include/linux/lsm_hook_defs.h | 4 +++ >> include/linux/security.h | 15 ++++++++ >> security/security.c | 42 ++++++++++++++++++++++ >> security/selinux/hooks.c | 55 +++++++++++++++++++++++++++++ >> security/selinux/include/classmap.h | 2 ++ >> 6 files changed, 130 insertions(+) > > My apologies for the late reply, I've been trying to work my way through > the review backlog but it has been taking longer than expected; comments > below ... No worries, I have also been busy these days. >> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c >> index 2aa0e219d721..65d9262a37f7 100644 >> --- a/security/selinux/hooks.c >> +++ b/security/selinux/hooks.c >> @@ -21,6 +21,7 @@ >> * Copyright (C) 2016 Mellanox Technologies >> */ >> >> +#include "av_permissions.h" >> #include <linux/init.h> >> #include <linux/kd.h> >> #include <linux/kernel.h> >> @@ -92,6 +93,7 @@ >> #include <linux/fsnotify.h> >> #include <linux/fanotify.h> >> #include <linux/io_uring.h> >> +#include <uapi/linux/virtio_ids.h> >> >> #include "avc.h" >> #include "objsec.h" >> @@ -6950,6 +6952,56 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) >> } >> #endif /* CONFIG_IO_URING */ >> >> +static int vduse_check_device_type(u32 sid, u32 device_id) >> +{ >> + u32 requested; >> + >> + if (device_id == VIRTIO_ID_NET) >> + requested = VDUSE__NET; >> + else if (device_id == VIRTIO_ID_BLOCK) >> + requested = VDUSE__BLOCK; >> + else >> + return -EINVAL; >> + >> + return avc_has_perm(sid, sid, SECCLASS_VDUSE, requested, NULL); >> +} >> + >> +static int selinux_vduse_dev_create(u32 device_id) >> +{ >> + u32 sid = current_sid(); >> + int ret; >> + >> + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVCREATE, NULL); >> + if (ret) >> + return ret; >> + >> + return vduse_check_device_type(sid, device_id); >> +} > > I see there has been some discussion about the need for a dedicated > create hook as opposed to using the existing ioctl controls. I think > one important point that has been missing from the discussion is the > idea of labeling the newly created device. Unfortunately prior to a > few minutes ago I hadn't ever looked at VDUSE so please correct me if > I get some things wrong :) > > From what I can see userspace creates a new VDUSE device with > ioctl(VDUSE_CREATE_DEV), which trigger the creation of a new > /dev/vduse/XXX device which will be labeled according to the udev > and SELinux configuration, likely with a generic udev label. My > question is if we want to be able to uniquely label each VDUSE > device based on the process that initiates the device creation > with the call to ioctl()? If that is the case, we would need a > create hook not only to control the creation of the device, but to > record the triggering process' label in the new device; this label > would then be used in subsequent VDUSE open and destroy operations. > The normal device file I/O operations would still be subject to the > standard SELinux file I/O permissions using the device file label > assigned by systemd/udev when the device was created. I don't think we need a unique label for VDUSE devices, but maybe Michael thinks otherwise? > >> +static int selinux_vduse_dev_destroy(u32 device_id) >> +{ >> + u32 sid = current_sid(); >> + int ret; >> + >> + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVDESTROY, NULL); >> + if (ret) >> + return ret; >> + >> + return vduse_check_device_type(sid, device_id); >> +} >> + >> +static int selinux_vduse_dev_open(u32 device_id) >> +{ >> + u32 sid = current_sid(); >> + int ret; >> + >> + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVOPEN, NULL); >> + if (ret) >> + return ret; >> + >> + return vduse_check_device_type(sid, device_id); >> +} >> + >> /* >> * IMPORTANT NOTE: When adding new hooks, please be careful to keep this order: >> * 1. any hooks that don't belong to (2.) or (3.) below, >> @@ -7243,6 +7295,9 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { >> #ifdef CONFIG_PERF_EVENTS >> LSM_HOOK_INIT(perf_event_alloc, selinux_perf_event_alloc), >> #endif >> + LSM_HOOK_INIT(vduse_dev_create, selinux_vduse_dev_create), >> + LSM_HOOK_INIT(vduse_dev_destroy, selinux_vduse_dev_destroy), >> + LSM_HOOK_INIT(vduse_dev_open, selinux_vduse_dev_open), >> }; >> >> static __init int selinux_init(void) >> diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h >> index a3c380775d41..d3dc37fb03d4 100644 >> --- a/security/selinux/include/classmap.h >> +++ b/security/selinux/include/classmap.h >> @@ -256,6 +256,8 @@ const struct security_class_mapping secclass_map[] = { >> { "override_creds", "sqpoll", "cmd", NULL } }, >> { "user_namespace", >> { "create", NULL } }, >> + { "vduse", >> + { "devcreate", "devdestroy", "devopen", "net", "block", NULL} }, > > I think we can just call the permissions "create", "open", and "destroy" > since the "dev" prefix is somewhat implied by this being a dedicated > VDUSE object class. Ack, I can remove the "dev" prefix in next revision. > > I don't see where you are using the "net" and "block" permissions above, > is this a leftover from a prior draft of this patch or are you planning > to do something with these permissions? It is actually used, but maybe not in a correct way. If you look at each hook, there are two checks performed: 1. Check for the operation type: create/destroy/open 2. Check for the device type: block/net It means that the application will have to combine one (or more) operation type with one (or more) device type. Does that make sense? Thanks, Maxime > >> { NULL } >> }; >> >> -- >> 2.41.0 > > -- > paul-moore.com >
On Fri, Dec 08, 2023 at 12:01:15PM +0100, Maxime Coquelin wrote: > Hello Paul, > > On 11/8/23 03:31, Paul Moore wrote: > > On Oct 20, 2023 "Michael S. Tsirkin" <mst@redhat.com> wrote: > > > > > > This patch introduces LSM hooks for devices creation, > > > destruction and opening operations, checking the > > > application is allowed to perform these operations for > > > the Virtio device type. > > > > > > Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> > > > --- > > > drivers/vdpa/vdpa_user/vduse_dev.c | 12 +++++++ > > > include/linux/lsm_hook_defs.h | 4 +++ > > > include/linux/security.h | 15 ++++++++ > > > security/security.c | 42 ++++++++++++++++++++++ > > > security/selinux/hooks.c | 55 +++++++++++++++++++++++++++++ > > > security/selinux/include/classmap.h | 2 ++ > > > 6 files changed, 130 insertions(+) > > > > My apologies for the late reply, I've been trying to work my way through > > the review backlog but it has been taking longer than expected; comments > > below ... > > No worries, I have also been busy these days. > > > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > > > index 2aa0e219d721..65d9262a37f7 100644 > > > --- a/security/selinux/hooks.c > > > +++ b/security/selinux/hooks.c > > > @@ -21,6 +21,7 @@ > > > * Copyright (C) 2016 Mellanox Technologies > > > */ > > > +#include "av_permissions.h" > > > #include <linux/init.h> > > > #include <linux/kd.h> > > > #include <linux/kernel.h> > > > @@ -92,6 +93,7 @@ > > > #include <linux/fsnotify.h> > > > #include <linux/fanotify.h> > > > #include <linux/io_uring.h> > > > +#include <uapi/linux/virtio_ids.h> > > > #include "avc.h" > > > #include "objsec.h" > > > @@ -6950,6 +6952,56 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) > > > } > > > #endif /* CONFIG_IO_URING */ > > > +static int vduse_check_device_type(u32 sid, u32 device_id) > > > +{ > > > + u32 requested; > > > + > > > + if (device_id == VIRTIO_ID_NET) > > > + requested = VDUSE__NET; > > > + else if (device_id == VIRTIO_ID_BLOCK) > > > + requested = VDUSE__BLOCK; > > > + else > > > + return -EINVAL; > > > + > > > + return avc_has_perm(sid, sid, SECCLASS_VDUSE, requested, NULL); > > > +} > > > + > > > +static int selinux_vduse_dev_create(u32 device_id) > > > +{ > > > + u32 sid = current_sid(); > > > + int ret; > > > + > > > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVCREATE, NULL); > > > + if (ret) > > > + return ret; > > > + > > > + return vduse_check_device_type(sid, device_id); > > > +} > > > > I see there has been some discussion about the need for a dedicated > > create hook as opposed to using the existing ioctl controls. I think > > one important point that has been missing from the discussion is the > > idea of labeling the newly created device. Unfortunately prior to a > > few minutes ago I hadn't ever looked at VDUSE so please correct me if > > I get some things wrong :) > > > > From what I can see userspace creates a new VDUSE device with > > ioctl(VDUSE_CREATE_DEV), which trigger the creation of a new > > /dev/vduse/XXX device which will be labeled according to the udev > > and SELinux configuration, likely with a generic udev label. My > > question is if we want to be able to uniquely label each VDUSE > > device based on the process that initiates the device creation > > with the call to ioctl()? If that is the case, we would need a > > create hook not only to control the creation of the device, but to > > record the triggering process' label in the new device; this label > > would then be used in subsequent VDUSE open and destroy operations. > > The normal device file I/O operations would still be subject to the > > standard SELinux file I/O permissions using the device file label > > assigned by systemd/udev when the device was created. > > I don't think we need a unique label for VDUSE devices, but maybe > Michael thinks otherwise? I don't know. All this is consumed by libvirt, you need to ask these guys. > > > > > +static int selinux_vduse_dev_destroy(u32 device_id) > > > +{ > > > + u32 sid = current_sid(); > > > + int ret; > > > + > > > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVDESTROY, NULL); > > > + if (ret) > > > + return ret; > > > + > > > + return vduse_check_device_type(sid, device_id); > > > +} > > > + > > > +static int selinux_vduse_dev_open(u32 device_id) > > > +{ > > > + u32 sid = current_sid(); > > > + int ret; > > > + > > > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVOPEN, NULL); > > > + if (ret) > > > + return ret; > > > + > > > + return vduse_check_device_type(sid, device_id); > > > +} > > > + > > > /* > > > * IMPORTANT NOTE: When adding new hooks, please be careful to keep this order: > > > * 1. any hooks that don't belong to (2.) or (3.) below, > > > @@ -7243,6 +7295,9 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { > > > #ifdef CONFIG_PERF_EVENTS > > > LSM_HOOK_INIT(perf_event_alloc, selinux_perf_event_alloc), > > > #endif > > > + LSM_HOOK_INIT(vduse_dev_create, selinux_vduse_dev_create), > > > + LSM_HOOK_INIT(vduse_dev_destroy, selinux_vduse_dev_destroy), > > > + LSM_HOOK_INIT(vduse_dev_open, selinux_vduse_dev_open), > > > }; > > > static __init int selinux_init(void) > > > diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h > > > index a3c380775d41..d3dc37fb03d4 100644 > > > --- a/security/selinux/include/classmap.h > > > +++ b/security/selinux/include/classmap.h > > > @@ -256,6 +256,8 @@ const struct security_class_mapping secclass_map[] = { > > > { "override_creds", "sqpoll", "cmd", NULL } }, > > > { "user_namespace", > > > { "create", NULL } }, > > > + { "vduse", > > > + { "devcreate", "devdestroy", "devopen", "net", "block", NULL} }, > > > > I think we can just call the permissions "create", "open", and "destroy" > > since the "dev" prefix is somewhat implied by this being a dedicated > > VDUSE object class. > > Ack, I can remove the "dev" prefix in next revision. > > > > > I don't see where you are using the "net" and "block" permissions above, > > is this a leftover from a prior draft of this patch or are you planning > > to do something with these permissions? > > It is actually used, but maybe not in a correct way. > If you look at each hook, there are two checks performed: > 1. Check for the operation type: create/destroy/open > 2. Check for the device type: block/net > > It means that the application will have to combine one (or more) > operation type with one (or more) device type. > > Does that make sense? > > Thanks, > Maxime > > > > > > { NULL } > > > }; > > > -- > > > 2.41.0 > > > > -- > > paul-moore.com > >
On 12/8/23 12:05, Michael S. Tsirkin wrote: > On Fri, Dec 08, 2023 at 12:01:15PM +0100, Maxime Coquelin wrote: >> Hello Paul, >> >> On 11/8/23 03:31, Paul Moore wrote: >>> On Oct 20, 2023 "Michael S. Tsirkin" <mst@redhat.com> wrote: >>>> >>>> This patch introduces LSM hooks for devices creation, >>>> destruction and opening operations, checking the >>>> application is allowed to perform these operations for >>>> the Virtio device type. >>>> >>>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> >>>> --- >>>> drivers/vdpa/vdpa_user/vduse_dev.c | 12 +++++++ >>>> include/linux/lsm_hook_defs.h | 4 +++ >>>> include/linux/security.h | 15 ++++++++ >>>> security/security.c | 42 ++++++++++++++++++++++ >>>> security/selinux/hooks.c | 55 +++++++++++++++++++++++++++++ >>>> security/selinux/include/classmap.h | 2 ++ >>>> 6 files changed, 130 insertions(+) >>> >>> My apologies for the late reply, I've been trying to work my way through >>> the review backlog but it has been taking longer than expected; comments >>> below ... >> >> No worries, I have also been busy these days. >> >>>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c >>>> index 2aa0e219d721..65d9262a37f7 100644 >>>> --- a/security/selinux/hooks.c >>>> +++ b/security/selinux/hooks.c >>>> @@ -21,6 +21,7 @@ >>>> * Copyright (C) 2016 Mellanox Technologies >>>> */ >>>> +#include "av_permissions.h" >>>> #include <linux/init.h> >>>> #include <linux/kd.h> >>>> #include <linux/kernel.h> >>>> @@ -92,6 +93,7 @@ >>>> #include <linux/fsnotify.h> >>>> #include <linux/fanotify.h> >>>> #include <linux/io_uring.h> >>>> +#include <uapi/linux/virtio_ids.h> >>>> #include "avc.h" >>>> #include "objsec.h" >>>> @@ -6950,6 +6952,56 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) >>>> } >>>> #endif /* CONFIG_IO_URING */ >>>> +static int vduse_check_device_type(u32 sid, u32 device_id) >>>> +{ >>>> + u32 requested; >>>> + >>>> + if (device_id == VIRTIO_ID_NET) >>>> + requested = VDUSE__NET; >>>> + else if (device_id == VIRTIO_ID_BLOCK) >>>> + requested = VDUSE__BLOCK; >>>> + else >>>> + return -EINVAL; >>>> + >>>> + return avc_has_perm(sid, sid, SECCLASS_VDUSE, requested, NULL); >>>> +} >>>> + >>>> +static int selinux_vduse_dev_create(u32 device_id) >>>> +{ >>>> + u32 sid = current_sid(); >>>> + int ret; >>>> + >>>> + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVCREATE, NULL); >>>> + if (ret) >>>> + return ret; >>>> + >>>> + return vduse_check_device_type(sid, device_id); >>>> +} >>> >>> I see there has been some discussion about the need for a dedicated >>> create hook as opposed to using the existing ioctl controls. I think >>> one important point that has been missing from the discussion is the >>> idea of labeling the newly created device. Unfortunately prior to a >>> few minutes ago I hadn't ever looked at VDUSE so please correct me if >>> I get some things wrong :) >>> >>> From what I can see userspace creates a new VDUSE device with >>> ioctl(VDUSE_CREATE_DEV), which trigger the creation of a new >>> /dev/vduse/XXX device which will be labeled according to the udev >>> and SELinux configuration, likely with a generic udev label. My >>> question is if we want to be able to uniquely label each VDUSE >>> device based on the process that initiates the device creation >>> with the call to ioctl()? If that is the case, we would need a >>> create hook not only to control the creation of the device, but to >>> record the triggering process' label in the new device; this label >>> would then be used in subsequent VDUSE open and destroy operations. >>> The normal device file I/O operations would still be subject to the >>> standard SELinux file I/O permissions using the device file label >>> assigned by systemd/udev when the device was created. >> >> I don't think we need a unique label for VDUSE devices, but maybe >> Michael thinks otherwise? > > I don't know. > All this is consumed by libvirt, you need to ask these guys. I think it is not consumed by libvirt, at least not in the usecases I have in mind. For networking devices, it will be consumed by OVS. Maxime
On Fri, Dec 08, 2023 at 01:23:00PM +0100, Maxime Coquelin wrote: > > > On 12/8/23 12:05, Michael S. Tsirkin wrote: > > On Fri, Dec 08, 2023 at 12:01:15PM +0100, Maxime Coquelin wrote: > > > Hello Paul, > > > > > > On 11/8/23 03:31, Paul Moore wrote: > > > > On Oct 20, 2023 "Michael S. Tsirkin" <mst@redhat.com> wrote: > > > > > > > > > > This patch introduces LSM hooks for devices creation, > > > > > destruction and opening operations, checking the > > > > > application is allowed to perform these operations for > > > > > the Virtio device type. > > > > > > > > > > Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> > > > > > --- > > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 12 +++++++ > > > > > include/linux/lsm_hook_defs.h | 4 +++ > > > > > include/linux/security.h | 15 ++++++++ > > > > > security/security.c | 42 ++++++++++++++++++++++ > > > > > security/selinux/hooks.c | 55 +++++++++++++++++++++++++++++ > > > > > security/selinux/include/classmap.h | 2 ++ > > > > > 6 files changed, 130 insertions(+) > > > > > > > > My apologies for the late reply, I've been trying to work my way through > > > > the review backlog but it has been taking longer than expected; comments > > > > below ... > > > > > > No worries, I have also been busy these days. > > > > > > > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > > > > > index 2aa0e219d721..65d9262a37f7 100644 > > > > > --- a/security/selinux/hooks.c > > > > > +++ b/security/selinux/hooks.c > > > > > @@ -21,6 +21,7 @@ > > > > > * Copyright (C) 2016 Mellanox Technologies > > > > > */ > > > > > +#include "av_permissions.h" > > > > > #include <linux/init.h> > > > > > #include <linux/kd.h> > > > > > #include <linux/kernel.h> > > > > > @@ -92,6 +93,7 @@ > > > > > #include <linux/fsnotify.h> > > > > > #include <linux/fanotify.h> > > > > > #include <linux/io_uring.h> > > > > > +#include <uapi/linux/virtio_ids.h> > > > > > #include "avc.h" > > > > > #include "objsec.h" > > > > > @@ -6950,6 +6952,56 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) > > > > > } > > > > > #endif /* CONFIG_IO_URING */ > > > > > +static int vduse_check_device_type(u32 sid, u32 device_id) > > > > > +{ > > > > > + u32 requested; > > > > > + > > > > > + if (device_id == VIRTIO_ID_NET) > > > > > + requested = VDUSE__NET; > > > > > + else if (device_id == VIRTIO_ID_BLOCK) > > > > > + requested = VDUSE__BLOCK; > > > > > + else > > > > > + return -EINVAL; > > > > > + > > > > > + return avc_has_perm(sid, sid, SECCLASS_VDUSE, requested, NULL); > > > > > +} > > > > > + > > > > > +static int selinux_vduse_dev_create(u32 device_id) > > > > > +{ > > > > > + u32 sid = current_sid(); > > > > > + int ret; > > > > > + > > > > > + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVCREATE, NULL); > > > > > + if (ret) > > > > > + return ret; > > > > > + > > > > > + return vduse_check_device_type(sid, device_id); > > > > > +} > > > > > > > > I see there has been some discussion about the need for a dedicated > > > > create hook as opposed to using the existing ioctl controls. I think > > > > one important point that has been missing from the discussion is the > > > > idea of labeling the newly created device. Unfortunately prior to a > > > > few minutes ago I hadn't ever looked at VDUSE so please correct me if > > > > I get some things wrong :) > > > > > > > > From what I can see userspace creates a new VDUSE device with > > > > ioctl(VDUSE_CREATE_DEV), which trigger the creation of a new > > > > /dev/vduse/XXX device which will be labeled according to the udev > > > > and SELinux configuration, likely with a generic udev label. My > > > > question is if we want to be able to uniquely label each VDUSE > > > > device based on the process that initiates the device creation > > > > with the call to ioctl()? If that is the case, we would need a > > > > create hook not only to control the creation of the device, but to > > > > record the triggering process' label in the new device; this label > > > > would then be used in subsequent VDUSE open and destroy operations. > > > > The normal device file I/O operations would still be subject to the > > > > standard SELinux file I/O permissions using the device file label > > > > assigned by systemd/udev when the device was created. > > > > > > I don't think we need a unique label for VDUSE devices, but maybe > > > Michael thinks otherwise? > > > > I don't know. > > All this is consumed by libvirt, you need to ask these guys. > > I think it is not consumed by libvirt, at least not in the usecases I > have in mind. For networking devices, it will be consumed by OVS. > > Maxime OK, ovs then :)
On 12/8/23 13:26, Michael S. Tsirkin wrote: > On Fri, Dec 08, 2023 at 01:23:00PM +0100, Maxime Coquelin wrote: >> >> >> On 12/8/23 12:05, Michael S. Tsirkin wrote: >>> On Fri, Dec 08, 2023 at 12:01:15PM +0100, Maxime Coquelin wrote: >>>> Hello Paul, >>>> >>>> On 11/8/23 03:31, Paul Moore wrote: >>>>> On Oct 20, 2023 "Michael S. Tsirkin" <mst@redhat.com> wrote: >>>>>> >>>>>> This patch introduces LSM hooks for devices creation, >>>>>> destruction and opening operations, checking the >>>>>> application is allowed to perform these operations for >>>>>> the Virtio device type. >>>>>> >>>>>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> >>>>>> --- >>>>>> drivers/vdpa/vdpa_user/vduse_dev.c | 12 +++++++ >>>>>> include/linux/lsm_hook_defs.h | 4 +++ >>>>>> include/linux/security.h | 15 ++++++++ >>>>>> security/security.c | 42 ++++++++++++++++++++++ >>>>>> security/selinux/hooks.c | 55 +++++++++++++++++++++++++++++ >>>>>> security/selinux/include/classmap.h | 2 ++ >>>>>> 6 files changed, 130 insertions(+) >>>>> >>>>> My apologies for the late reply, I've been trying to work my way through >>>>> the review backlog but it has been taking longer than expected; comments >>>>> below ... >>>> >>>> No worries, I have also been busy these days. >>>> >>>>>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c >>>>>> index 2aa0e219d721..65d9262a37f7 100644 >>>>>> --- a/security/selinux/hooks.c >>>>>> +++ b/security/selinux/hooks.c >>>>>> @@ -21,6 +21,7 @@ >>>>>> * Copyright (C) 2016 Mellanox Technologies >>>>>> */ >>>>>> +#include "av_permissions.h" >>>>>> #include <linux/init.h> >>>>>> #include <linux/kd.h> >>>>>> #include <linux/kernel.h> >>>>>> @@ -92,6 +93,7 @@ >>>>>> #include <linux/fsnotify.h> >>>>>> #include <linux/fanotify.h> >>>>>> #include <linux/io_uring.h> >>>>>> +#include <uapi/linux/virtio_ids.h> >>>>>> #include "avc.h" >>>>>> #include "objsec.h" >>>>>> @@ -6950,6 +6952,56 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) >>>>>> } >>>>>> #endif /* CONFIG_IO_URING */ >>>>>> +static int vduse_check_device_type(u32 sid, u32 device_id) >>>>>> +{ >>>>>> + u32 requested; >>>>>> + >>>>>> + if (device_id == VIRTIO_ID_NET) >>>>>> + requested = VDUSE__NET; >>>>>> + else if (device_id == VIRTIO_ID_BLOCK) >>>>>> + requested = VDUSE__BLOCK; >>>>>> + else >>>>>> + return -EINVAL; >>>>>> + >>>>>> + return avc_has_perm(sid, sid, SECCLASS_VDUSE, requested, NULL); >>>>>> +} >>>>>> + >>>>>> +static int selinux_vduse_dev_create(u32 device_id) >>>>>> +{ >>>>>> + u32 sid = current_sid(); >>>>>> + int ret; >>>>>> + >>>>>> + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVCREATE, NULL); >>>>>> + if (ret) >>>>>> + return ret; >>>>>> + >>>>>> + return vduse_check_device_type(sid, device_id); >>>>>> +} >>>>> >>>>> I see there has been some discussion about the need for a dedicated >>>>> create hook as opposed to using the existing ioctl controls. I think >>>>> one important point that has been missing from the discussion is the >>>>> idea of labeling the newly created device. Unfortunately prior to a >>>>> few minutes ago I hadn't ever looked at VDUSE so please correct me if >>>>> I get some things wrong :) >>>>> >>>>> From what I can see userspace creates a new VDUSE device with >>>>> ioctl(VDUSE_CREATE_DEV), which trigger the creation of a new >>>>> /dev/vduse/XXX device which will be labeled according to the udev >>>>> and SELinux configuration, likely with a generic udev label. My >>>>> question is if we want to be able to uniquely label each VDUSE >>>>> device based on the process that initiates the device creation >>>>> with the call to ioctl()? If that is the case, we would need a >>>>> create hook not only to control the creation of the device, but to >>>>> record the triggering process' label in the new device; this label >>>>> would then be used in subsequent VDUSE open and destroy operations. >>>>> The normal device file I/O operations would still be subject to the >>>>> standard SELinux file I/O permissions using the device file label >>>>> assigned by systemd/udev when the device was created. >>>> >>>> I don't think we need a unique label for VDUSE devices, but maybe >>>> Michael thinks otherwise? >>> >>> I don't know. >>> All this is consumed by libvirt, you need to ask these guys. >> >> I think it is not consumed by libvirt, at least not in the usecases I >> have in mind. For networking devices, it will be consumed by OVS. >> >> Maxime > > OK, ovs then :) > Adding Aaron, our go-to person for SELinux-related topics for OVS, but I think we don't need to do relabeling for VDUSE chardevs. Aaron, do you confirm? Maxime
diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c index 0243dee9cf0e..ca64eac11ddb 100644 --- a/drivers/vdpa/vdpa_user/vduse_dev.c +++ b/drivers/vdpa/vdpa_user/vduse_dev.c @@ -8,6 +8,7 @@ * */ +#include "linux/security.h" #include <linux/init.h> #include <linux/module.h> #include <linux/cdev.h> @@ -1443,6 +1444,10 @@ static int vduse_dev_open(struct inode *inode, struct file *file) if (dev->connected) goto unlock; + ret = -EPERM; + if (security_vduse_dev_open(dev->device_id)) + goto unlock; + ret = 0; dev->connected = true; file->private_data = dev; @@ -1655,6 +1660,9 @@ static int vduse_destroy_dev(char *name) if (!dev) return -EINVAL; + if (security_vduse_dev_destroy(dev->device_id)) + return -EPERM; + mutex_lock(&dev->lock); if (dev->vdev || dev->connected) { mutex_unlock(&dev->lock); @@ -1819,6 +1827,10 @@ static int vduse_create_dev(struct vduse_dev_config *config, int ret; struct vduse_dev *dev; + ret = -EPERM; + if (security_vduse_dev_create(config->device_id)) + goto err; + ret = -EEXIST; if (vduse_find_dev(config->name)) goto err; diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index ac962c4cb44b..0b3999ab3264 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -419,3 +419,7 @@ LSM_HOOK(int, 0, uring_override_creds, const struct cred *new) LSM_HOOK(int, 0, uring_sqpoll, void) LSM_HOOK(int, 0, uring_cmd, struct io_uring_cmd *ioucmd) #endif /* CONFIG_IO_URING */ + +LSM_HOOK(int, 0, vduse_dev_create, u32 device_id) +LSM_HOOK(int, 0, vduse_dev_destroy, u32 device_id) +LSM_HOOK(int, 0, vduse_dev_open, u32 device_id) diff --git a/include/linux/security.h b/include/linux/security.h index 5f16eecde00b..a650c500f841 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -484,6 +484,9 @@ int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen); int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen); int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen); int security_locked_down(enum lockdown_reason what); +int security_vduse_dev_create(u32 device_id); +int security_vduse_dev_destroy(u32 device_id); +int security_vduse_dev_open(u32 device_id); #else /* CONFIG_SECURITY */ static inline int call_blocking_lsm_notifier(enum lsm_event event, void *data) @@ -1395,6 +1398,18 @@ static inline int security_locked_down(enum lockdown_reason what) { return 0; } +static inline int security_vduse_dev_create(u32 device_id) +{ + return 0; +} +static inline int security_vduse_dev_destroy(u32 device_id) +{ + return 0; +} +static inline int security_vduse_dev_open(u32 device_id) +{ + return 0; +} #endif /* CONFIG_SECURITY */ #if defined(CONFIG_SECURITY) && defined(CONFIG_WATCH_QUEUE) diff --git a/security/security.c b/security/security.c index 23b129d482a7..8d7d4d2eca0b 100644 --- a/security/security.c +++ b/security/security.c @@ -5337,3 +5337,45 @@ int security_uring_cmd(struct io_uring_cmd *ioucmd) return call_int_hook(uring_cmd, 0, ioucmd); } #endif /* CONFIG_IO_URING */ + +/** + * security_vduse_dev_create() - Check if a VDUSE device type creation is allowed + * @device_id: the Virtio device ID + * + * Check whether the Virtio device creation is allowed + * + * Return: Returns 0 if permission is granted. + */ +int security_vduse_dev_create(u32 device_id) +{ + return call_int_hook(vduse_dev_create, 0, device_id); +} +EXPORT_SYMBOL(security_vduse_dev_create); + +/** + * security_vduse_dev_destroy() - Check if a VDUSE device type destruction is allowed + * @device_id: the Virtio device ID + * + * Check whether the Virtio device destruction is allowed + * + * Return: Returns 0 if permission is granted. + */ +int security_vduse_dev_destroy(u32 device_id) +{ + return call_int_hook(vduse_dev_destroy, 0, device_id); +} +EXPORT_SYMBOL(security_vduse_dev_destroy); + +/** + * security_vduse_dev_open() - Check if a VDUSE device type opening is allowed + * @device_id: the Virtio device ID + * + * Check whether the Virtio device opening is allowed + * + * Return: Returns 0 if permission is granted. + */ +int security_vduse_dev_open(u32 device_id) +{ + return call_int_hook(vduse_dev_open, 0, device_id); +} +EXPORT_SYMBOL(security_vduse_dev_open); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 2aa0e219d721..65d9262a37f7 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -21,6 +21,7 @@ * Copyright (C) 2016 Mellanox Technologies */ +#include "av_permissions.h" #include <linux/init.h> #include <linux/kd.h> #include <linux/kernel.h> @@ -92,6 +93,7 @@ #include <linux/fsnotify.h> #include <linux/fanotify.h> #include <linux/io_uring.h> +#include <uapi/linux/virtio_ids.h> #include "avc.h" #include "objsec.h" @@ -6950,6 +6952,56 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) } #endif /* CONFIG_IO_URING */ +static int vduse_check_device_type(u32 sid, u32 device_id) +{ + u32 requested; + + if (device_id == VIRTIO_ID_NET) + requested = VDUSE__NET; + else if (device_id == VIRTIO_ID_BLOCK) + requested = VDUSE__BLOCK; + else + return -EINVAL; + + return avc_has_perm(sid, sid, SECCLASS_VDUSE, requested, NULL); +} + +static int selinux_vduse_dev_create(u32 device_id) +{ + u32 sid = current_sid(); + int ret; + + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVCREATE, NULL); + if (ret) + return ret; + + return vduse_check_device_type(sid, device_id); +} + +static int selinux_vduse_dev_destroy(u32 device_id) +{ + u32 sid = current_sid(); + int ret; + + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVDESTROY, NULL); + if (ret) + return ret; + + return vduse_check_device_type(sid, device_id); +} + +static int selinux_vduse_dev_open(u32 device_id) +{ + u32 sid = current_sid(); + int ret; + + ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVOPEN, NULL); + if (ret) + return ret; + + return vduse_check_device_type(sid, device_id); +} + /* * IMPORTANT NOTE: When adding new hooks, please be careful to keep this order: * 1. any hooks that don't belong to (2.) or (3.) below, @@ -7243,6 +7295,9 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { #ifdef CONFIG_PERF_EVENTS LSM_HOOK_INIT(perf_event_alloc, selinux_perf_event_alloc), #endif + LSM_HOOK_INIT(vduse_dev_create, selinux_vduse_dev_create), + LSM_HOOK_INIT(vduse_dev_destroy, selinux_vduse_dev_destroy), + LSM_HOOK_INIT(vduse_dev_open, selinux_vduse_dev_open), }; static __init int selinux_init(void) diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index a3c380775d41..d3dc37fb03d4 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -256,6 +256,8 @@ const struct security_class_mapping secclass_map[] = { { "override_creds", "sqpoll", "cmd", NULL } }, { "user_namespace", { "create", NULL } }, + { "vduse", + { "devcreate", "devdestroy", "devopen", "net", "block", NULL} }, { NULL } };
This patch introduces LSM hooks for devices creation, destruction and opening operations, checking the application is allowed to perform these operations for the Virtio device type. Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com> --- drivers/vdpa/vdpa_user/vduse_dev.c | 12 +++++++ include/linux/lsm_hook_defs.h | 4 +++ include/linux/security.h | 15 ++++++++ security/security.c | 42 ++++++++++++++++++++++ security/selinux/hooks.c | 55 +++++++++++++++++++++++++++++ security/selinux/include/classmap.h | 2 ++ 6 files changed, 130 insertions(+)