Re: [PATCH] virtio-blk: make the queue depth configurable

From: Bjorn Helgaas
Date: Wed Mar 19 2014 - 12:58:22 EST

On Wed, Mar 19, 2014 at 12:37 AM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
> Joe Perches <joe@xxxxxxxxxxx> writes:
>> On Sun, 2014-03-16 at 22:00 -0700, Joe Perches wrote:
>>> On Mon, 2014-03-17 at 14:25 +1030, Rusty Russell wrote:
>>>
>>> > Erk, our tests are insufficient. Testbuilding an allmodconfig with this
>>> > now:
>>>
>>> Good idea.
>>>
>>> > diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
>>> []
>>> > @@ -188,6 +188,9 @@ struct kparam_array
>>> > /* Default value instead of permissions? */ \
>>> > static int __param_perm_check_##name __attribute__((unused)) = \
>>> > BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)) \
>>> > + /* User perms >= group perms >= other perms. */ \
>>> > + + BUILD_BUG_ON_ZERO(((perm) >> 6) < (((perm) >> 3) & 7)) \
>>> > + + BUILD_BUG_ON_ZERO((((perm) >> 3) & 7) < ((perm) & 7)) \
>>> > + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN); \
>>> > static const char __param_str_##name[] = prefix #name; \
>>> > static struct kernel_param __moduleparam_const __param_##name \
>>>
>>> It might make sense to separate this octal permissions
>>> test into a new macro for other checks in macros like
>>> CLASS_ATTR, DEVICE_ATTR, SENSOR_ATTR and SENSOR_ATTR_2.
>
> OK, I took your bikeshed and re-painted it below.
>
>> #define VERIFY_OCTAL_PERMISSIONS(perms) \
>> ({ \
>> if (__builtin_constant_p(perms)) { \
>> BUILD_BUG_ON((perms) < 0); \
>> BUILD_BUG_ON((perms) > 0777); \
>> /* User perms >= group perms >= other perms */ \
>> BUILD_BUG_ON(((perms) >> 6) < (((perms) >> 3) & 7)); \
>> BUILD_BUG_ON((((perms) >> 3) & 7) < ((perms) & 7)); \
>> } \
>> ; \
>> })
>
> Subject: VERIFY_OCTAL_PERMISSIONS: stricter checking for sysfs perms.
>
> Summary of http://lkml.org/lkml/2014/3/14/363 :
>
> Ted: module_param(queue_depth, int, 444)
> Joe: 0444!
> Rusty: User perms >= group perms >= other perms?
> Joe: CLASS_ATTR, DEVICE_ATTR, SENSOR_ATTR and SENSOR_ATTR_2?
>
> Side effect of stricter permissions means removing the unnecessary
> S_IFREG from drivers/pci/slot.c.
>
> Suggested-by: Joe Perches <joe@xxxxxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> for drivers/pci/slot.c

It looks like fs/ocfs2/cluster/sys.c and fs/ocfs2/stackglue.c also use
S_IFREG in a similar way.

> diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c
> index 7dd62fa9d0bd..396c200b9ddb 100644
> --- a/drivers/pci/slot.c
> +++ b/drivers/pci/slot.c
> @@ -116,11 +116,11 @@ static void pci_slot_release(struct kobject *kobj)
> }
>
> static struct pci_slot_attribute pci_slot_attr_address =
> - __ATTR(address, (S_IFREG | S_IRUGO), address_read_file, NULL);
> + __ATTR(address, S_IRUGO, address_read_file, NULL);
> static struct pci_slot_attribute pci_slot_attr_max_speed =
> - __ATTR(max_bus_speed, (S_IFREG | S_IRUGO), max_speed_read_file, NULL);
> + __ATTR(max_bus_speed, S_IRUGO, max_speed_read_file, NULL);
> static struct pci_slot_attribute pci_slot_attr_cur_speed =
> - __ATTR(cur_bus_speed, (S_IFREG | S_IRUGO), cur_speed_read_file, NULL);
> + __ATTR(cur_bus_speed, S_IRUGO, cur_speed_read_file, NULL);
>
> static struct attribute *pci_slot_default_attrs[] = {
> &pci_slot_attr_address.attr,
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 471090093c67..945afeb3058a 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -842,4 +842,13 @@ static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
> # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
> #endif
>
> +/* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
> +#define VERIFY_OCTAL_PERMISSIONS(perms) \
> + ((__builtin_constant_p(perms) ? \
> + BUILD_BUG_ON_ZERO((perms) < 0) + \
> + BUILD_BUG_ON_ZERO((perms) > 0777) + \
> + /* User perms >= group perms >= other perms */ \
> + BUILD_BUG_ON_ZERO(((perms) >> 6) < (((perms) >> 3) & 7)) + \
> + BUILD_BUG_ON_ZERO((((perms) >> 3) & 7) < ((perms) & 7)): 0) + \
> + (perms))
> #endif
> diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
> index 175f6995d1af..204a67743804 100644
> --- a/include/linux/moduleparam.h
> +++ b/include/linux/moduleparam.h
> @@ -186,14 +186,12 @@ struct kparam_array
> parameters. */
> #define __module_param_call(prefix, name, ops, arg, perm, level) \
> /* Default value instead of permissions? */ \
> - static int __param_perm_check_##name __attribute__((unused)) = \
> - BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)) \
> - + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN); \
> - static const char __param_str_##name[] = prefix #name; \
> + static const char __param_str_##name[] = prefix #name; \
> static struct kernel_param __moduleparam_const __param_##name \
> __used \
> __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
> - = { __param_str_##name, ops, perm, level, { arg } }
> + = { __param_str_##name, ops, VERIFY_OCTAL_PERMISSIONS(perm), \
> + level, { arg } }
>
> /* Obsolete - use module_param_cb() */
> #define module_param_call(name, set, get, arg, perm) \
> diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
> index 30b2ebee6439..f517e6e488c8 100644
> --- a/include/linux/sysfs.h
> +++ b/include/linux/sysfs.h
> @@ -71,7 +71,8 @@ struct attribute_group {
> */
>
> #define __ATTR(_name, _mode, _show, _store) { \
> - .attr = {.name = __stringify(_name), .mode = _mode }, \
> + .attr = {.name = __stringify(_name), \
> + .mode = VERIFY_OCTAL_PERMISSIONS(_mode) }, \
> .show = _show, \
> .store = _store, \
> }
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