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SubjectRe: [PATCH v5 2/2] staging: ion: create one device entry per heap
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On 09/27/2017 06:20 AM, Benjamin Gaignard wrote:
> Instead a getting only one common device "/dev/ion" for
> all the heaps this patch allow to create one device
> entry ("/dev/ionX") per heap.
> Getting an entry per heap could allow to set security rules
> per heap and global ones for all heaps.
>
> Allocation requests will be only allowed if the mask_id
> match with device minor.
> Query request could be done on any of the devices.
>
Thinking about this a bit more, I'm not 100% sure if this
will allow the security rules we want. Heap ids are assigned
dynamically and therefore so will the /dev/ionX designation.
From my understanding, security rules like selinux need to
be fully specified at boot time so I'm not sure how you would
be able to write rules to differentiate between /dev/ionX and
/dev/ionY without knowing the values at boottime.

So I think we need a different way to match the heap ids to
get the security we want unless my understanding of security
policies is wrong and we can dynamically specify permissions.

Thanks,
Laura
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> ---
> version 5:
> - create a configuration flag to keep legacy Ion misc device
>
> version 4:
> - add a configuration flag to switch between legacy Ion misc device
> and one device per heap version.
>
> version 3:
> - change ion_device_add_heap prototype to return a possible error.
>
> version 2:
> - simplify ioctl check like propose by Dan
> - make sure that we don't register more than ION_DEV_MAX heaps.
>
> drivers/staging/android/TODO | 1 -
> drivers/staging/android/ion/Kconfig | 7 +++++++
> drivers/staging/android/ion/ion-ioctl.c | 18 ++++++++++++++++--
> drivers/staging/android/ion/ion.c | 31 ++++++++++++++++++++++++++++++-
> drivers/staging/android/ion/ion.h | 15 +++++++++++++--
> 5 files changed, 66 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/staging/android/TODO b/drivers/staging/android/TODO
> index 5f14247..d770ffa 100644
> --- a/drivers/staging/android/TODO
> +++ b/drivers/staging/android/TODO
> @@ -9,7 +9,6 @@ TODO:
> ion/
> - Add dt-bindings for remaining heaps (chunk and carveout heaps). This would
> involve putting appropriate bindings in a memory node for Ion to find.
> - - Split /dev/ion up into multiple nodes (e.g. /dev/ion/heap0)
> - Better test framework (integration with VGEM was suggested)
>
> Please send patches to Greg Kroah-Hartman <greg@kroah.com> and Cc:
> diff --git a/drivers/staging/android/ion/Kconfig b/drivers/staging/android/ion/Kconfig
> index a517b2d..cb4666e 100644
> --- a/drivers/staging/android/ion/Kconfig
> +++ b/drivers/staging/android/ion/Kconfig
> @@ -10,6 +10,13 @@ menuconfig ION
> If you're not using Android its probably safe to
> say N here.
>
> +config ION_LEGACY_DEVICE_API
> + bool "Keep using Ion legacy misc device API"
> + depends on ION
> + help
> + Choose this option to keep using Ion legacy misc device API
> + i.e. /dev/ion
> +
> config ION_SYSTEM_HEAP
> bool "Ion system heap"
> depends on ION
> diff --git a/drivers/staging/android/ion/ion-ioctl.c b/drivers/staging/android/ion/ion-ioctl.c
> index e26b786..bb5c77b 100644
> --- a/drivers/staging/android/ion/ion-ioctl.c
> +++ b/drivers/staging/android/ion/ion-ioctl.c
> @@ -25,7 +25,8 @@ union ion_ioctl_arg {
> struct ion_heap_query query;
> };
>
> -static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
> +static int validate_ioctl_arg(struct file *filp,
> + unsigned int cmd, union ion_ioctl_arg *arg)
> {
> switch (cmd) {
> case ION_IOC_HEAP_QUERY:
> @@ -34,6 +35,19 @@ static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
> arg->query.reserved2 )
> return -EINVAL;
> break;
> +
> + case ION_IOC_ALLOC:
> + {
> + int mask = 1 << iminor(filp->f_inode);
> +
> +#ifdef CONFIG_ION_LEGACY_DEVICE_API
> + if (imajor(filp->f_inode) == MISC_MAJOR)
> + return 0;
> +#endif
> + if (!(arg->allocation.heap_id_mask & mask))
> + return -EINVAL;
> + break;
> + }
> default:
> break;
> }
> @@ -69,7 +83,7 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
> return -EFAULT;
>
> - ret = validate_ioctl_arg(cmd, &data);
> + ret = validate_ioctl_arg(filp, cmd, &data);
> if (WARN_ON_ONCE(ret))
> return ret;
>
> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> index 93e2c90..092b24c 100644
> --- a/drivers/staging/android/ion/ion.c
> +++ b/drivers/staging/android/ion/ion.c
> @@ -40,6 +40,8 @@
>
> #include "ion.h"
>
> +#define ION_DEV_MAX 32
> +
> static struct ion_device *internal_dev;
> static int heap_id;
>
> @@ -537,15 +539,28 @@ static int debug_shrink_get(void *data, u64 *val)
> DEFINE_SIMPLE_ATTRIBUTE(debug_shrink_fops, debug_shrink_get,
> debug_shrink_set, "%llu\n");
>
> -void ion_device_add_heap(struct ion_heap *heap)
> +int ion_device_add_heap(struct ion_heap *heap)
> {
> struct dentry *debug_file;
> struct ion_device *dev = internal_dev;
> + int ret = 0;
>
> if (!heap->ops->allocate || !heap->ops->free)
> pr_err("%s: can not add heap with invalid ops struct.\n",
> __func__);
>
> + if (heap_id >= ION_DEV_MAX)
> + return -EBUSY;
> +
> + heap->ddev.devt = MKDEV(MAJOR(dev->devt), heap_id);
> + dev_set_name(&heap->ddev, "ion%d", heap_id);
> + device_initialize(&heap->ddev);
> + cdev_init(&heap->chrdev, &ion_fops);
> + heap->chrdev.owner = THIS_MODULE;
> + ret = cdev_device_add(&heap->chrdev, &heap->ddev);
> + if (ret < 0)
> + return ret;
> +
> spin_lock_init(&heap->free_lock);
> heap->free_list_size = 0;
>
> @@ -583,6 +598,8 @@ void ion_device_add_heap(struct ion_heap *heap)
>
> dev->heap_cnt++;
> up_write(&dev->lock);
> +
> + return ret;
> }
> EXPORT_SYMBOL(ion_device_add_heap);
>
> @@ -595,6 +612,7 @@ static int ion_device_create(void)
> if (!idev)
> return -ENOMEM;
>
> +#ifdef CONFIG_ION_LEGACY_DEVICE_API
> idev->dev.minor = MISC_DYNAMIC_MINOR;
> idev->dev.name = "ion";
> idev->dev.fops = &ion_fops;
> @@ -605,6 +623,17 @@ static int ion_device_create(void)
> kfree(idev);
> return ret;
> }
> +#endif
> +
> + ret = alloc_chrdev_region(&idev->devt, 0, ION_DEV_MAX, "ion");
> + if (ret) {
> + pr_err("ion: unable to allocate device\n");
> +#ifdef CONFIG_ION_LEGACY_DEVICE_API
> + misc_deregister(&idev->dev);
> +#endif
> + kfree(idev);
> + return ret;
> + }
>
> idev->debug_root = debugfs_create_dir("ion", NULL);
> if (!idev->debug_root) {
> diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h
> index 621e5f7..2b00ccb 100644
> --- a/drivers/staging/android/ion/ion.h
> +++ b/drivers/staging/android/ion/ion.h
> @@ -17,16 +17,19 @@
> #ifndef _ION_H
> #define _ION_H
>
> +#include <linux/cdev.h>
> #include <linux/device.h>
> #include <linux/dma-direction.h>
> #include <linux/kref.h>
> +#ifdef CONFIG_ION_LEGACY_DEVICE_API
> +#include <linux/miscdevice.h>
> +#endif
> #include <linux/mm_types.h>
> #include <linux/mutex.h>
> #include <linux/rbtree.h>
> #include <linux/sched.h>
> #include <linux/shrinker.h>
> #include <linux/types.h>
> -#include <linux/miscdevice.h>
>
> #include "../uapi/ion.h"
>
> @@ -91,12 +94,16 @@ void ion_buffer_destroy(struct ion_buffer *buffer);
> /**
> * struct ion_device - the metadata of the ion device node
> * @dev: the actual misc device
> + * @devt: Ion device
> * @buffers: an rb tree of all the existing buffers
> * @buffer_lock: lock protecting the tree of buffers
> * @lock: rwsem protecting the tree of heaps and clients
> */
> struct ion_device {
> +#ifdef CONFIG_ION_LEGACY_DEVICE_API
> struct miscdevice dev;
> +#endif
> + dev_t devt;
> struct rb_root buffers;
> struct mutex buffer_lock;
> struct rw_semaphore lock;
> @@ -152,6 +159,8 @@ struct ion_heap_ops {
> * struct ion_heap - represents a heap in the system
> * @node: rb node to put the heap on the device's tree of heaps
> * @dev: back pointer to the ion_device
> + * @ddev: device structure
> + * @chrdev: associated character device
> * @type: type of heap
> * @ops: ops struct as above
> * @flags: flags
> @@ -176,6 +185,8 @@ struct ion_heap_ops {
> struct ion_heap {
> struct plist_node node;
> struct ion_device *dev;
> + struct device ddev;
> + struct cdev chrdev;
> enum ion_heap_type type;
> struct ion_heap_ops *ops;
> unsigned long flags;
> @@ -212,7 +223,7 @@ bool ion_buffer_fault_user_mappings(struct ion_buffer *buffer);
> * ion_device_add_heap - adds a heap to the ion device
> * @heap: the heap to add
> */
> -void ion_device_add_heap(struct ion_heap *heap);
> +int ion_device_add_heap(struct ion_heap *heap);
>
> /**
> * some helpers for common operations on buffers using the sg_table
>

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