Re: [PATCH v4 2/4] of: overlay: global sysfs enable attribute

[Rob Herring]

On Fri, Jun 12, 2015 at 2:38 PM, Pantelis Antoniou
 wrote:
> A throw once master enable switch to protect against any
> further overlay applications if the administrator desires so.
>
> Signed-off-by: Pantelis Antoniou 

I had some questioning whether we want more states than just on/off
like "only add sub-trees", but I've convinced myself it is better to
keep the kill switch simple. So I'm okay with patches 1 and 2 (and the
relevant part of 4 if you want to split it). I think #3 needs to be
part of how we expect userspace to interact with overlays.

Please respin and I will queue at least the kill switch for 4.4 unless
there are further comments.

Rob


> ---
>  drivers/of/overlay.c | 43 ++-
>  1 file changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index f17f5ef..37ec858 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -21,6 +21,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>
>  #include "of_private.h"
>
> @@ -55,8 +56,12 @@ struct of_overlay {
> struct kobject kobj;
>  };
>
> +/* master enable switch; once set to 0 can't be re-enabled */
> +static atomic_t ov_enable = ATOMIC_INIT(1);
> +
>  static int of_overlay_apply_one(struct of_overlay *ov,
> struct device_node *target, const struct device_node 
> *overlay);
> +static int overlay_removal_is_ok(struct of_overlay *ov);
>
>  static int of_overlay_apply_single_property(struct of_overlay *ov,
> struct device_node *target, struct property *prop)
> @@ -339,6 +344,35 @@ void of_overlay_release(struct kobject *kobj)
> kfree(ov);
>  }
>
> +static ssize_t enable_show(struct kobject *kobj,
> +   struct kobj_attribute *attr, char *buf)
> +{
> +   return snprintf(buf, PAGE_SIZE, "%d\n", atomic_read(_enable));
> +}
> +
> +static ssize_t enable_store(struct kobject *kobj,
> +   struct kobj_attribute *attr, const char *buf, size_t count)
> +{
> +   int ret;
> +   bool new_enable;
> +
> +   ret = strtobool(buf, _enable);
> +   if (ret != 0)
> +   return ret;
> +   /* if we've disabled it, no going back */
> +   if (atomic_read(_enable) == 0)
> +   return -EPERM;
> +   atomic_set(_enable, (int)new_enable);
> +   return count;
> +}
> +
> +static struct kobj_attribute enable_attr = __ATTR_RW(enable);
> +
> +static const struct attribute *overlay_global_attrs[] = {
> +   _attr.attr,
> +   NULL
> +};
> +
>  static struct kobj_type of_overlay_ktype = {
> .release = of_overlay_release,
>  };
> @@ -360,6 +394,10 @@ int of_overlay_create(struct device_node *tree)
> struct of_overlay *ov;
> int err, id;
>
> +   /* administratively disabled */
> +   if (!atomic_read(_enable))
> +   return -EPERM;
> +
> /* allocate the overlay structure */
> ov = kzalloc(sizeof(*ov), GFP_KERNEL);
> if (ov == NULL)
> @@ -596,5 +634,8 @@ int of_overlay_init(void)
> if (!ov_kset)
> return -ENOMEM;
>
> -   return 0;
> +   rc = sysfs_create_files(_kset->kobj, overlay_global_attrs);
> +   WARN(rc, "%s: error adding global attributes\n", __func__);
> +
> +   return rc;
>  }
> --
> 1.7.12
>
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Re: [PATCH v4 2/4] of: overlay: global sysfs enable attribute

[Rob Herring]

On Fri, Jun 12, 2015 at 2:38 PM, Pantelis Antoniou
 wrote:
> A throw once master enable switch to protect against any
> further overlay applications if the administrator desires so.
>
> Signed-off-by: Pantelis Antoniou 

I had some questioning whether we want more states than just on/off
like "only add sub-trees", but I've convinced myself it is better to
keep the kill switch simple. So I'm okay with patches 1 and 2 (and the
relevant part of 4 if you want to split it). I think #3 needs to be
part of how we expect userspace to interact with overlays.

Please respin and I will queue at least the kill switch for 4.4 unless
there are further comments.

Rob


> ---
>  drivers/of/overlay.c | 43 ++-
>  1 file changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index f17f5ef..37ec858 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -21,6 +21,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>
>  #include "of_private.h"
>
> @@ -55,8 +56,12 @@ struct of_overlay {
> struct kobject kobj;
>  };
>
> +/* master enable switch; once set to 0 can't be re-enabled */
> +static atomic_t ov_enable = ATOMIC_INIT(1);
> +
>  static int of_overlay_apply_one(struct of_overlay *ov,
> struct device_node *target, const struct device_node 
> *overlay);
> +static int overlay_removal_is_ok(struct of_overlay *ov);
>
>  static int of_overlay_apply_single_property(struct of_overlay *ov,
> struct device_node *target, struct property *prop)
> @@ -339,6 +344,35 @@ void of_overlay_release(struct kobject *kobj)
> kfree(ov);
>  }
>
> +static ssize_t enable_show(struct kobject *kobj,
> +   struct kobj_attribute *attr, char *buf)
> +{
> +   return snprintf(buf, PAGE_SIZE, "%d\n", atomic_read(_enable));
> +}
> +
> +static ssize_t enable_store(struct kobject *kobj,
> +   struct kobj_attribute *attr, const char *buf, size_t count)
> +{
> +   int ret;
> +   bool new_enable;
> +
> +   ret = strtobool(buf, _enable);
> +   if (ret != 0)
> +   return ret;
> +   /* if we've disabled it, no going back */
> +   if (atomic_read(_enable) == 0)
> +   return -EPERM;
> +   atomic_set(_enable, (int)new_enable);
> +   return count;
> +}
> +
> +static struct kobj_attribute enable_attr = __ATTR_RW(enable);
> +
> +static const struct attribute *overlay_global_attrs[] = {
> +   _attr.attr,
> +   NULL
> +};
> +
>  static struct kobj_type of_overlay_ktype = {
> .release = of_overlay_release,
>  };
> @@ -360,6 +394,10 @@ int of_overlay_create(struct device_node *tree)
> struct of_overlay *ov;
> int err, id;
>
> +   /* administratively disabled */
> +   if (!atomic_read(_enable))
> +   return -EPERM;
> +
> /* allocate the overlay structure */
> ov = kzalloc(sizeof(*ov), GFP_KERNEL);
> if (ov == NULL)
> @@ -596,5 +634,8 @@ int of_overlay_init(void)
> if (!ov_kset)
> return -ENOMEM;
>
> -   return 0;
> +   rc = sysfs_create_files(_kset->kobj, overlay_global_attrs);
> +   WARN(rc, "%s: error adding global attributes\n", __func__);
> +
> +   return rc;
>  }
> --
> 1.7.12
>
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[PATCH v4 2/4] of: overlay: global sysfs enable attribute

[Pantelis Antoniou]

A throw once master enable switch to protect against any
further overlay applications if the administrator desires so.

Signed-off-by: Pantelis Antoniou 
---
 drivers/of/overlay.c | 43 ++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index f17f5ef..37ec858 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -21,6 +21,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include "of_private.h"
 
@@ -55,8 +56,12 @@ struct of_overlay {
struct kobject kobj;
 };
 
+/* master enable switch; once set to 0 can't be re-enabled */
+static atomic_t ov_enable = ATOMIC_INIT(1);
+
 static int of_overlay_apply_one(struct of_overlay *ov,
struct device_node *target, const struct device_node *overlay);
+static int overlay_removal_is_ok(struct of_overlay *ov);
 
 static int of_overlay_apply_single_property(struct of_overlay *ov,
struct device_node *target, struct property *prop)
@@ -339,6 +344,35 @@ void of_overlay_release(struct kobject *kobj)
kfree(ov);
 }
 
+static ssize_t enable_show(struct kobject *kobj,
+   struct kobj_attribute *attr, char *buf)
+{
+   return snprintf(buf, PAGE_SIZE, "%d\n", atomic_read(_enable));
+}
+
+static ssize_t enable_store(struct kobject *kobj,
+   struct kobj_attribute *attr, const char *buf, size_t count)
+{
+   int ret;
+   bool new_enable;
+
+   ret = strtobool(buf, _enable);
+   if (ret != 0)
+   return ret;
+   /* if we've disabled it, no going back */
+   if (atomic_read(_enable) == 0)
+   return -EPERM;
+   atomic_set(_enable, (int)new_enable);
+   return count;
+}
+
+static struct kobj_attribute enable_attr = __ATTR_RW(enable);
+
+static const struct attribute *overlay_global_attrs[] = {
+   _attr.attr,
+   NULL
+};
+
 static struct kobj_type of_overlay_ktype = {
.release = of_overlay_release,
 };
@@ -360,6 +394,10 @@ int of_overlay_create(struct device_node *tree)
struct of_overlay *ov;
int err, id;
 
+   /* administratively disabled */
+   if (!atomic_read(_enable))
+   return -EPERM;
+
/* allocate the overlay structure */
ov = kzalloc(sizeof(*ov), GFP_KERNEL);
if (ov == NULL)
@@ -596,5 +634,8 @@ int of_overlay_init(void)
if (!ov_kset)
return -ENOMEM;
 
-   return 0;
+   rc = sysfs_create_files(_kset->kobj, overlay_global_attrs);
+   WARN(rc, "%s: error adding global attributes\n", __func__);
+
+   return rc;
 }
-- 
1.7.12

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[PATCH v4 2/4] of: overlay: global sysfs enable attribute

[Pantelis Antoniou]

A throw once master enable switch to protect against any
further overlay applications if the administrator desires so.

Signed-off-by: Pantelis Antoniou pantelis.anton...@konsulko.com
---
 drivers/of/overlay.c | 43 ++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index f17f5ef..37ec858 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -21,6 +21,7 @@
 #include linux/err.h
 #include linux/idr.h
 #include linux/sysfs.h
+#include linux/atomic.h
 
 #include of_private.h
 
@@ -55,8 +56,12 @@ struct of_overlay {
struct kobject kobj;
 };
 
+/* master enable switch; once set to 0 can't be re-enabled */
+static atomic_t ov_enable = ATOMIC_INIT(1);
+
 static int of_overlay_apply_one(struct of_overlay *ov,
struct device_node *target, const struct device_node *overlay);
+static int overlay_removal_is_ok(struct of_overlay *ov);
 
 static int of_overlay_apply_single_property(struct of_overlay *ov,
struct device_node *target, struct property *prop)
@@ -339,6 +344,35 @@ void of_overlay_release(struct kobject *kobj)
kfree(ov);
 }
 
+static ssize_t enable_show(struct kobject *kobj,
+   struct kobj_attribute *attr, char *buf)
+{
+   return snprintf(buf, PAGE_SIZE, %d\n, atomic_read(ov_enable));
+}
+
+static ssize_t enable_store(struct kobject *kobj,
+   struct kobj_attribute *attr, const char *buf, size_t count)
+{
+   int ret;
+   bool new_enable;
+
+   ret = strtobool(buf, new_enable);
+   if (ret != 0)
+   return ret;
+   /* if we've disabled it, no going back */
+   if (atomic_read(ov_enable) == 0)
+   return -EPERM;
+   atomic_set(ov_enable, (int)new_enable);
+   return count;
+}
+
+static struct kobj_attribute enable_attr = __ATTR_RW(enable);
+
+static const struct attribute *overlay_global_attrs[] = {
+   enable_attr.attr,
+   NULL
+};
+
 static struct kobj_type of_overlay_ktype = {
.release = of_overlay_release,
 };
@@ -360,6 +394,10 @@ int of_overlay_create(struct device_node *tree)
struct of_overlay *ov;
int err, id;
 
+   /* administratively disabled */
+   if (!atomic_read(ov_enable))
+   return -EPERM;
+
/* allocate the overlay structure */
ov = kzalloc(sizeof(*ov), GFP_KERNEL);
if (ov == NULL)
@@ -596,5 +634,8 @@ int of_overlay_init(void)
if (!ov_kset)
return -ENOMEM;
 
-   return 0;
+   rc = sysfs_create_files(ov_kset-kobj, overlay_global_attrs);
+   WARN(rc, %s: error adding global attributes\n, __func__);
+
+   return rc;
 }
-- 
1.7.12

--
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