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Message-ID: <87ior9r193.fsf@rustcorp.com.au>
Date: Thu, 20 Mar 2014 14:05:04 +1030
From: Rusty Russell <rusty@...tcorp.com.au>
To: Joe Perches <joe@...ches.com>, Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Theodore Ts'o <tytso@....edu>,
Linux Kernel Developers List <linux-kernel@...r.kernel.org>,
"Michael S. Tsirkin" <mst@...hat.com>,
virtio-dev@...ts.oasis-open.org,
virtualization@...ts.linux-foundation.org, fes@...gle.com,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] virtio-blk: make the queue depth configurable
Joe Perches <joe@...ches.com> writes:
> Couple more bikesheddy things:
>
> Is there ever a reason to use a non __builtin_const_p(perms)?
It's a bit conservative, and anyway, the test is useless since AFAICT
BUILD_BUG_ON() is a noop if !__builtin_const_p(). I removed it
and re-tested.
> Maybe that should be a BUILD_BUG_ON too
> BUILD_BUG_ON(!builtin_const_p_perms)
>
> My brain of little size gets confused by the
> BUILD_BUG_ON_ZERO(foo) +
> vs
> BUILD_BUG_ON(foo);
> as it just seems like more text for the same content.
>
> Is there any value on the "_ZERO(foo) +" I don't understand?
I don't like to use statement expressions unless we really need them,
and BUILD_BUG_ON_ZERO() was build for this purpose.
Cheers,
Rusty.
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 several callers.
Suggested-by: Joe Perches <joe@...ches.com>
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com> for drivers/pci/slot.c
Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Miklos Szeredi <miklos@...redi.hu>
Cc: Mark Fasheh <mfasheh@...e.com>
Cc: Joel Becker <jlbec@...lplan.org>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
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/fs/fuse/cuse.c b/fs/fuse/cuse.c
index b96a49b37d66..77cf5eeeabd1 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -568,7 +568,7 @@ static ssize_t cuse_class_waiting_show(struct device *dev,
return sprintf(buf, "%d\n", atomic_read(&cc->fc.num_waiting));
}
-static DEVICE_ATTR(waiting, S_IFREG | 0400, cuse_class_waiting_show, NULL);
+static DEVICE_ATTR(waiting, 0400, cuse_class_waiting_show, NULL);
static ssize_t cuse_class_abort_store(struct device *dev,
struct device_attribute *attr,
@@ -579,7 +579,7 @@ static ssize_t cuse_class_abort_store(struct device *dev,
fuse_abort_conn(&cc->fc);
return count;
}
-static DEVICE_ATTR(abort, S_IFREG | 0200, NULL, cuse_class_abort_store);
+static DEVICE_ATTR(abort, 0200, NULL, cuse_class_abort_store);
static struct attribute *cuse_class_dev_attrs[] = {
&dev_attr_waiting.attr,
diff --git a/fs/ocfs2/cluster/sys.c b/fs/ocfs2/cluster/sys.c
index a4b07730b2e1..b7f57271d49c 100644
--- a/fs/ocfs2/cluster/sys.c
+++ b/fs/ocfs2/cluster/sys.c
@@ -41,7 +41,7 @@ static ssize_t version_show(struct kobject *kobj, struct kobj_attribute *attr,
return snprintf(buf, PAGE_SIZE, "%u\n", O2NM_API_VERSION);
}
static struct kobj_attribute attr_version =
- __ATTR(interface_revision, S_IFREG | S_IRUGO, version_show, NULL);
+ __ATTR(interface_revision, S_IRUGO, version_show, NULL);
static struct attribute *o2cb_attrs[] = {
&attr_version.attr,
diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
index 1324e6600e57..25e9f7b5bad3 100644
--- a/fs/ocfs2/stackglue.c
+++ b/fs/ocfs2/stackglue.c
@@ -494,7 +494,7 @@ static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
}
static struct kobj_attribute ocfs2_attr_max_locking_protocol =
- __ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
+ __ATTR(max_locking_protocol, S_IRUGO,
ocfs2_max_locking_protocol_show, NULL);
static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
@@ -526,7 +526,7 @@ static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
}
static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
- __ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
+ __ATTR(loaded_cluster_plugins, S_IRUGO,
ocfs2_loaded_cluster_plugins_show, NULL);
static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
@@ -548,7 +548,7 @@ static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
}
static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
- __ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
+ __ATTR(active_cluster_plugin, S_IRUGO,
ocfs2_active_cluster_plugin_show, NULL);
static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
@@ -597,7 +597,7 @@ static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
static struct kobj_attribute ocfs2_attr_cluster_stack =
- __ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
+ __ATTR(cluster_stack, S_IRUGO | S_IWUSR,
ocfs2_cluster_stack_show,
ocfs2_cluster_stack_store);
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 471090093c67..4679eddc110a 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -842,4 +842,12 @@ 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) \
+ (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)) + \
+ (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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