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kernel/ksysfs.c: expose file_caps_enabled in sysfs

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A kernel booted with no_file_caps allows to install fscaps on a binary
but doesn't actually honor the fscaps when running the binary. Userspace
currently has no sane way to determine whether installing fscaps
actually has any effect. Since parsing /proc/cmdline is fragile this
patch exposes the current setting (1 or 0) via /sys/kernel/fscaps

Signed-off-by: Ludwig Nussel <ludwig.nussel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Ludwig Nussel 2011-02-28 15:57:17 +01:00 committed by Greg Kroah-Hartman
parent aed65af1cc
commit 088ab0b4d8
2 changed files with 18 additions and 0 deletions
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8
Documentation/ABI/testing/sysfs-kernel-fscaps Normal file
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@ -0,0 +1,8 @@
What: /sys/kernel/fscaps
Date: February 2011
KernelVersion: 2.6.38
Contact: Ludwig Nussel <ludwig.nussel@suse.de>
Description
Shows whether file system capabilities are honored
when executing a binary

10
kernel/ksysfs.c
View File

@ -16,6 +16,7 @@
#include <linux/kexec.h> #include <linux/kexec.h>
#include <linux/profile.h> #include <linux/profile.h>
#include <linux/sched.h> #include <linux/sched.h>
#include <linux/capability.h>
#define KERNEL_ATTR_RO(_name) \ #define KERNEL_ATTR_RO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RO(_name) static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
@ -131,6 +132,14 @@ KERNEL_ATTR_RO(vmcoreinfo);
#endif /* CONFIG_KEXEC */ #endif /* CONFIG_KEXEC */
/* whether file capabilities are enabled */
static ssize_t fscaps_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", file_caps_enabled);
}
KERNEL_ATTR_RO(fscaps);
/* /*
* Make /sys/kernel/notes give the raw contents of our kernel .notes section. * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
*/ */
@ -158,6 +167,7 @@ struct kobject *kernel_kobj;
EXPORT_SYMBOL_GPL(kernel_kobj); EXPORT_SYMBOL_GPL(kernel_kobj);
static struct attribute * kernel_attrs[] = { static struct attribute * kernel_attrs[] = {
&fscaps_attr.attr,
#if defined(CONFIG_HOTPLUG) #if defined(CONFIG_HOTPLUG)
&uevent_seqnum_attr.attr, &uevent_seqnum_attr.attr,
&uevent_helper_attr.attr, &uevent_helper_attr.attr,