Helps reviewing and understanding these checks. v2: Remove misplaced newlines.
Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Reviewed-by: David Herrmann dh.herrmann@gmail.com --- drivers/gpu/drm/drm_drv.c | 113 ++++++++++++++++++++++++++++++--------------- 1 file changed, 75 insertions(+), 38 deletions(-)
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index ec651be..05e3053 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -286,6 +286,44 @@ static int drm_version(struct drm_device *dev, void *data, }
/** + * drm_ioctl_permit - Check ioctl permissions against caller + * + * @flags: ioctl permission flags. + * @file_priv: Pointer to struct drm_file identifying the caller. + * + * Checks whether the caller is allowed to run an ioctl with the + * indicated permissions. If so, returns zero. Otherwise returns an + * error code suitable for ioctl return. + */ +static int drm_ioctl_permit(u32 flags, struct drm_file *file_priv) +{ + /* ROOT_ONLY is only for CAP_SYS_ADMIN */ + if (unlikely((flags & DRM_ROOT_ONLY) && !capable(CAP_SYS_ADMIN))) + return -EACCES; + + /* AUTH is only for authenticated or render client */ + if (unlikely((flags & DRM_AUTH) && !drm_is_render_client(file_priv) && + !file_priv->authenticated)) + return -EACCES; + + /* MASTER is only for master */ + if (unlikely((flags & DRM_MASTER) && !file_priv->is_master)) + return -EACCES; + + /* Control clients must be explicitly allowed */ + if (unlikely(!(flags & DRM_CONTROL_ALLOW) && + file_priv->minor->type == DRM_MINOR_CONTROL)) + return -EACCES; + + /* Render clients must be explicitly allowed */ + if (unlikely(!(flags & DRM_RENDER_ALLOW) && + drm_is_render_client(file_priv))) + return -EACCES; + + return 0; +} + +/** * Called whenever a process performs an ioctl on /dev/drm. * * \param inode device inode. @@ -350,52 +388,51 @@ long drm_ioctl(struct file *filp, /* Do not trust userspace, use our own definition */ func = ioctl->func;
- if (!func) { + if (unlikely(!func)) { DRM_DEBUG("no function\n"); retcode = -EINVAL; - } else if (((ioctl->flags & DRM_ROOT_ONLY) && !capable(CAP_SYS_ADMIN)) || - ((ioctl->flags & DRM_AUTH) && !drm_is_render_client(file_priv) && !file_priv->authenticated) || - ((ioctl->flags & DRM_MASTER) && !file_priv->is_master) || - (!(ioctl->flags & DRM_CONTROL_ALLOW) && (file_priv->minor->type == DRM_MINOR_CONTROL)) || - (!(ioctl->flags & DRM_RENDER_ALLOW) && drm_is_render_client(file_priv))) { - retcode = -EACCES; - } else { - if (cmd & (IOC_IN | IOC_OUT)) { - if (asize <= sizeof(stack_kdata)) { - kdata = stack_kdata; - } else { - kdata = kmalloc(asize, GFP_KERNEL); - if (!kdata) { - retcode = -ENOMEM; - goto err_i1; - } - } - if (asize > usize) - memset(kdata + usize, 0, asize - usize); - } + goto err_i1; + }
- if (cmd & IOC_IN) { - if (copy_from_user(kdata, (void __user *)arg, - usize) != 0) { - retcode = -EFAULT; + retcode = drm_ioctl_permit(ioctl->flags, file_priv); + if (unlikely(retcode)) + goto err_i1; + + if (cmd & (IOC_IN | IOC_OUT)) { + if (asize <= sizeof(stack_kdata)) { + kdata = stack_kdata; + } else { + kdata = kmalloc(asize, GFP_KERNEL); + if (!kdata) { + retcode = -ENOMEM; goto err_i1; } - } else - memset(kdata, 0, usize); - - if (ioctl->flags & DRM_UNLOCKED) - retcode = func(dev, kdata, file_priv); - else { - mutex_lock(&drm_global_mutex); - retcode = func(dev, kdata, file_priv); - mutex_unlock(&drm_global_mutex); } + if (asize > usize) + memset(kdata + usize, 0, asize - usize); + }
- if (cmd & IOC_OUT) { - if (copy_to_user((void __user *)arg, kdata, - usize) != 0) - retcode = -EFAULT; + if (cmd & IOC_IN) { + if (copy_from_user(kdata, (void __user *)arg, + usize) != 0) { + retcode = -EFAULT; + goto err_i1; } + } else + memset(kdata, 0, usize); + + if (ioctl->flags & DRM_UNLOCKED) + retcode = func(dev, kdata, file_priv); + else { + mutex_lock(&drm_global_mutex); + retcode = func(dev, kdata, file_priv); + mutex_unlock(&drm_global_mutex); + } + + if (cmd & IOC_OUT) { + if (copy_to_user((void __user *)arg, kdata, + usize) != 0) + retcode = -EFAULT; }
err_i1: