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472 lines
13 KiB
472 lines
13 KiB
/* |
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* Created: Tue Feb 2 08:37:54 1999 by [email protected] |
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* |
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* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas. |
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* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California. |
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* All Rights Reserved. |
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* |
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* Author Rickard E. (Rik) Faith <[email protected]> |
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* Author Gareth Hughes <[email protected]> |
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* |
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* Permission is hereby granted, free of charge, to any person obtaining a |
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* copy of this software and associated documentation files (the "Software"), |
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* to deal in the Software without restriction, including without limitation |
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* the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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* and/or sell copies of the Software, and to permit persons to whom the |
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* Software is furnished to do so, subject to the following conditions: |
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* |
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* The above copyright notice and this permission notice (including the next |
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* paragraph) shall be included in all copies or substantial portions of the |
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* Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR |
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, |
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
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* OTHER DEALINGS IN THE SOFTWARE. |
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*/ |
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#include <linux/slab.h> |
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#include <drm/drm_auth.h> |
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#include <drm/drm_drv.h> |
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#include <drm/drm_file.h> |
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#include <drm/drm_lease.h> |
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#include <drm/drm_print.h> |
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#include "drm_internal.h" |
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#include "drm_legacy.h" |
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/** |
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* DOC: master and authentication |
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* |
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* &struct drm_master is used to track groups of clients with open |
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* primary/legacy device nodes. For every &struct drm_file which has had at |
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* least once successfully became the device master (either through the |
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* SET_MASTER IOCTL, or implicitly through opening the primary device node when |
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* no one else is the current master that time) there exists one &drm_master. |
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* This is noted in &drm_file.is_master. All other clients have just a pointer |
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* to the &drm_master they are associated with. |
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* |
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* In addition only one &drm_master can be the current master for a &drm_device. |
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* It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or |
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* implicitly through closing/opening the primary device node. See also |
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* drm_is_current_master(). |
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* |
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* Clients can authenticate against the current master (if it matches their own) |
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* using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters, |
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* this allows controlled access to the device for an entire group of mutually |
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* trusted clients. |
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*/ |
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static bool drm_is_current_master_locked(struct drm_file *fpriv) |
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{ |
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lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) || |
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lockdep_is_held(&fpriv->minor->dev->master_mutex)); |
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return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; |
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} |
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/** |
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* drm_is_current_master - checks whether @priv is the current master |
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* @fpriv: DRM file private |
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* |
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* Checks whether @fpriv is current master on its device. This decides whether a |
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* client is allowed to run DRM_MASTER IOCTLs. |
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* |
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* Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting |
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* - the current master is assumed to own the non-shareable display hardware. |
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*/ |
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bool drm_is_current_master(struct drm_file *fpriv) |
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{ |
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bool ret; |
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spin_lock(&fpriv->master_lookup_lock); |
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ret = drm_is_current_master_locked(fpriv); |
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spin_unlock(&fpriv->master_lookup_lock); |
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return ret; |
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} |
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EXPORT_SYMBOL(drm_is_current_master); |
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int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv) |
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{ |
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struct drm_auth *auth = data; |
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int ret = 0; |
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mutex_lock(&dev->master_mutex); |
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if (!file_priv->magic) { |
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ret = idr_alloc(&file_priv->master->magic_map, file_priv, |
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1, 0, GFP_KERNEL); |
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if (ret >= 0) |
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file_priv->magic = ret; |
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} |
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auth->magic = file_priv->magic; |
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mutex_unlock(&dev->master_mutex); |
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drm_dbg_core(dev, "%u\n", auth->magic); |
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return ret < 0 ? ret : 0; |
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} |
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int drm_authmagic(struct drm_device *dev, void *data, |
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struct drm_file *file_priv) |
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{ |
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struct drm_auth *auth = data; |
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struct drm_file *file; |
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drm_dbg_core(dev, "%u\n", auth->magic); |
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mutex_lock(&dev->master_mutex); |
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file = idr_find(&file_priv->master->magic_map, auth->magic); |
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if (file) { |
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file->authenticated = 1; |
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idr_replace(&file_priv->master->magic_map, NULL, auth->magic); |
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} |
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mutex_unlock(&dev->master_mutex); |
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return file ? 0 : -EINVAL; |
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} |
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struct drm_master *drm_master_create(struct drm_device *dev) |
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{ |
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struct drm_master *master; |
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master = kzalloc(sizeof(*master), GFP_KERNEL); |
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if (!master) |
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return NULL; |
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kref_init(&master->refcount); |
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drm_master_legacy_init(master); |
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idr_init(&master->magic_map); |
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master->dev = dev; |
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/* initialize the tree of output resource lessees */ |
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INIT_LIST_HEAD(&master->lessees); |
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INIT_LIST_HEAD(&master->lessee_list); |
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idr_init(&master->leases); |
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idr_init(&master->lessee_idr); |
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return master; |
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} |
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static void drm_set_master(struct drm_device *dev, struct drm_file *fpriv, |
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bool new_master) |
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{ |
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dev->master = drm_master_get(fpriv->master); |
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if (dev->driver->master_set) |
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dev->driver->master_set(dev, fpriv, new_master); |
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fpriv->was_master = true; |
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} |
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static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv) |
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{ |
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struct drm_master *old_master; |
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struct drm_master *new_master; |
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lockdep_assert_held_once(&dev->master_mutex); |
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WARN_ON(fpriv->is_master); |
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old_master = fpriv->master; |
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new_master = drm_master_create(dev); |
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if (!new_master) |
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return -ENOMEM; |
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spin_lock(&fpriv->master_lookup_lock); |
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fpriv->master = new_master; |
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spin_unlock(&fpriv->master_lookup_lock); |
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fpriv->is_master = 1; |
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fpriv->authenticated = 1; |
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drm_set_master(dev, fpriv, true); |
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if (old_master) |
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drm_master_put(&old_master); |
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return 0; |
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} |
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/* |
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* In the olden days the SET/DROP_MASTER ioctls used to return EACCES when |
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* CAP_SYS_ADMIN was not set. This was used to prevent rogue applications |
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* from becoming master and/or failing to release it. |
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* |
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* At the same time, the first client (for a given VT) is _always_ master. |
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* Thus in order for the ioctls to succeed, one had to _explicitly_ run the |
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* application as root or flip the setuid bit. |
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* |
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* If the CAP_SYS_ADMIN was missing, no other client could become master... |
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* EVER :-( Leading to a) the graphics session dying badly or b) a completely |
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* locked session. |
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* |
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* |
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* As some point systemd-logind was introduced to orchestrate and delegate |
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* master as applicable. It does so by opening the fd and passing it to users |
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* while in itself logind a) does the set/drop master per users' request and |
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* b) * implicitly drops master on VT switch. |
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* |
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* Even though logind looks like the future, there are a few issues: |
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* - some platforms don't have equivalent (Android, CrOS, some BSDs) so |
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* root is required _solely_ for SET/DROP MASTER. |
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* - applications may not be updated to use it, |
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* - any client which fails to drop master* can DoS the application using |
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* logind, to a varying degree. |
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* |
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* * Either due missing CAP_SYS_ADMIN or simply not calling DROP_MASTER. |
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* |
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* |
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* Here we implement the next best thing: |
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* - ensure the logind style of fd passing works unchanged, and |
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* - allow a client to drop/set master, iff it is/was master at a given point |
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* in time. |
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* |
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* Note: DROP_MASTER cannot be free for all, as an arbitrator user could: |
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* - DoS/crash the arbitrator - details would be implementation specific |
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* - open the node, become master implicitly and cause issues |
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* |
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* As a result this fixes the following when using root-less build w/o logind |
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* - startx |
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* - weston |
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* - various compositors based on wlroots |
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*/ |
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static int |
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drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv) |
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{ |
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if (file_priv->pid == task_pid(current) && file_priv->was_master) |
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return 0; |
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if (!capable(CAP_SYS_ADMIN)) |
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return -EACCES; |
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return 0; |
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} |
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int drm_setmaster_ioctl(struct drm_device *dev, void *data, |
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struct drm_file *file_priv) |
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{ |
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int ret; |
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mutex_lock(&dev->master_mutex); |
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ret = drm_master_check_perm(dev, file_priv); |
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if (ret) |
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goto out_unlock; |
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if (drm_is_current_master_locked(file_priv)) |
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goto out_unlock; |
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if (dev->master) { |
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ret = -EBUSY; |
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goto out_unlock; |
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} |
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if (!file_priv->master) { |
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ret = -EINVAL; |
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goto out_unlock; |
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} |
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if (!file_priv->is_master) { |
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ret = drm_new_set_master(dev, file_priv); |
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goto out_unlock; |
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} |
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if (file_priv->master->lessor != NULL) { |
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drm_dbg_lease(dev, |
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"Attempt to set lessee %d as master\n", |
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file_priv->master->lessee_id); |
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ret = -EINVAL; |
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goto out_unlock; |
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} |
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drm_set_master(dev, file_priv, false); |
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out_unlock: |
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mutex_unlock(&dev->master_mutex); |
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return ret; |
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} |
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static void drm_drop_master(struct drm_device *dev, |
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struct drm_file *fpriv) |
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{ |
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if (dev->driver->master_drop) |
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dev->driver->master_drop(dev, fpriv); |
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drm_master_put(&dev->master); |
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} |
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int drm_dropmaster_ioctl(struct drm_device *dev, void *data, |
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struct drm_file *file_priv) |
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{ |
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int ret; |
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mutex_lock(&dev->master_mutex); |
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ret = drm_master_check_perm(dev, file_priv); |
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if (ret) |
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goto out_unlock; |
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if (!drm_is_current_master_locked(file_priv)) { |
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ret = -EINVAL; |
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goto out_unlock; |
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} |
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if (!dev->master) { |
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ret = -EINVAL; |
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goto out_unlock; |
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} |
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if (file_priv->master->lessor != NULL) { |
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drm_dbg_lease(dev, |
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"Attempt to drop lessee %d as master\n", |
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file_priv->master->lessee_id); |
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ret = -EINVAL; |
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goto out_unlock; |
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} |
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drm_drop_master(dev, file_priv); |
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out_unlock: |
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mutex_unlock(&dev->master_mutex); |
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return ret; |
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} |
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int drm_master_open(struct drm_file *file_priv) |
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{ |
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struct drm_device *dev = file_priv->minor->dev; |
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int ret = 0; |
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/* if there is no current master make this fd it, but do not create |
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* any master object for render clients |
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*/ |
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mutex_lock(&dev->master_mutex); |
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if (!dev->master) { |
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ret = drm_new_set_master(dev, file_priv); |
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} else { |
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spin_lock(&file_priv->master_lookup_lock); |
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file_priv->master = drm_master_get(dev->master); |
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spin_unlock(&file_priv->master_lookup_lock); |
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} |
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mutex_unlock(&dev->master_mutex); |
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return ret; |
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} |
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void drm_master_release(struct drm_file *file_priv) |
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{ |
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struct drm_device *dev = file_priv->minor->dev; |
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struct drm_master *master; |
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mutex_lock(&dev->master_mutex); |
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master = file_priv->master; |
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if (file_priv->magic) |
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idr_remove(&file_priv->master->magic_map, file_priv->magic); |
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if (!drm_is_current_master_locked(file_priv)) |
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goto out; |
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drm_legacy_lock_master_cleanup(dev, master); |
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if (dev->master == file_priv->master) |
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drm_drop_master(dev, file_priv); |
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out: |
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if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_master) { |
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/* Revoke any leases held by this or lessees, but only if |
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* this is the "real" master |
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*/ |
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drm_lease_revoke(master); |
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} |
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/* drop the master reference held by the file priv */ |
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if (file_priv->master) |
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drm_master_put(&file_priv->master); |
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mutex_unlock(&dev->master_mutex); |
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} |
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/** |
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* drm_master_get - reference a master pointer |
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* @master: &struct drm_master |
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* |
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* Increments the reference count of @master and returns a pointer to @master. |
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*/ |
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struct drm_master *drm_master_get(struct drm_master *master) |
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{ |
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kref_get(&master->refcount); |
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return master; |
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} |
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EXPORT_SYMBOL(drm_master_get); |
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/** |
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* drm_file_get_master - reference &drm_file.master of @file_priv |
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* @file_priv: DRM file private |
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* |
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* Increments the reference count of @file_priv's &drm_file.master and returns |
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* the &drm_file.master. If @file_priv has no &drm_file.master, returns NULL. |
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* |
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* Master pointers returned from this function should be unreferenced using |
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* drm_master_put(). |
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*/ |
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struct drm_master *drm_file_get_master(struct drm_file *file_priv) |
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{ |
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struct drm_master *master = NULL; |
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spin_lock(&file_priv->master_lookup_lock); |
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if (!file_priv->master) |
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goto unlock; |
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master = drm_master_get(file_priv->master); |
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unlock: |
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spin_unlock(&file_priv->master_lookup_lock); |
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return master; |
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} |
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EXPORT_SYMBOL(drm_file_get_master); |
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static void drm_master_destroy(struct kref *kref) |
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{ |
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struct drm_master *master = container_of(kref, struct drm_master, refcount); |
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struct drm_device *dev = master->dev; |
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if (drm_core_check_feature(dev, DRIVER_MODESET)) |
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drm_lease_destroy(master); |
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drm_legacy_master_rmmaps(dev, master); |
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idr_destroy(&master->magic_map); |
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idr_destroy(&master->leases); |
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idr_destroy(&master->lessee_idr); |
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kfree(master->unique); |
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kfree(master); |
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} |
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/** |
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* drm_master_put - unreference and clear a master pointer |
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* @master: pointer to a pointer of &struct drm_master |
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* |
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* This decrements the &drm_master behind @master and sets it to NULL. |
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*/ |
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void drm_master_put(struct drm_master **master) |
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{ |
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kref_put(&(*master)->refcount, drm_master_destroy); |
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*master = NULL; |
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} |
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EXPORT_SYMBOL(drm_master_put); |
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/* Used by drm_client and drm_fb_helper */ |
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bool drm_master_internal_acquire(struct drm_device *dev) |
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{ |
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mutex_lock(&dev->master_mutex); |
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if (dev->master) { |
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mutex_unlock(&dev->master_mutex); |
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return false; |
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} |
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return true; |
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} |
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EXPORT_SYMBOL(drm_master_internal_acquire); |
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/* Used by drm_client and drm_fb_helper */ |
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void drm_master_internal_release(struct drm_device *dev) |
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{ |
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mutex_unlock(&dev->master_mutex); |
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} |
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EXPORT_SYMBOL(drm_master_internal_release);
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